Content:

ERE – Energy, Resources and the Environment

ERE1.1 – Energy, Resources & the Environment

EGU2020-20237 | Displays | ERE1.1

EDGAR v5.0: a tool to evaluate the influence of technology incorporation and regulatory frameworks on global greenhouse gases and air pollutant emissions.

Gabriel David Oreggioni, Fabio Monforti-Ferraio, Monica Crippa, Edwin Schaaf, Diego Guizzardi, Marilena Muntean, Marlene Duerr, and Elisabetta Vignati

During the last 30 years, the global energy sector has undergone through significant transformation, delivering a considerably larger electricity output whilst attempting to reduce air pollutant and greenhouse gas emissions. The international community has tackled this challenging dilemma by implementing different kind of policies and by encouraging several types of technological changes; including the partial replacement of coal and liquid fossil fuels by low carbon energy vectors (natural gas and renewable sources), the incorporation of more efficient power trains (natural gas fired combined cycles and supercritical coal fired plants) and the deployment of primary and secondary treatment processes for limiting air pollutant concentration in flue gases.
EDGAR is a unique global emission database due to its high sectorial, technological and geographical coverage; reporting greenhouse and air pollutant emission time series (1970-nowadays) in a very detailed way. Research is currently being conducted, aimed at updating the energy conversion and end of pipe processes so that the quantified emissions can better reflect the latest global and regional changes. By using EDGAR new data, it is possible to evaluate the impact of technology and regulatory frameworks on air pollutant emissions as well as to identify possible co-benefits and trade off associated with climate change mitigation policies for the energy industries.
This work is intended to study the drivers for greenhouse and air pollutant emission trends within this sector - both in large emitting developed and developing economies; by focusing on the role of  demand increase, on the penetration of non-fossil sources and specially on the incorporation of more efficient power islands, combustion and air pollutant abatement units.

How to cite: Oreggioni, G. D., Monforti-Ferraio, F., Crippa, M., Schaaf, E., Guizzardi, D., Muntean, M., Duerr, M., and Vignati, E.: EDGAR v5.0: a tool to evaluate the influence of technology incorporation and regulatory frameworks on global greenhouse gases and air pollutant emissions., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20237, https://doi.org/10.5194/egusphere-egu2020-20237, 2020.

EGU2020-20072 | Displays | ERE1.1

Vitamin C as a green high-performance CO2 scrubber

Linda Pastero, Alessandra Marengo, Davide Bernasconi, Guido Scarafia, and Alessandro Pavese

Carbon dioxide is a greenhouse gas and a natural component of the atmosphere, essential for plant life. Natural reservoirs (oceans, soils, etc.) regulate its geochemical cycle, but the anthropic activity disturbs this balance. In order to control the concentration of carbon dioxide in the atmosphere, many synergic CO2 capture and sequestration methods (Aresta and Dibenedetto, 2007; Bachu, 2008; Baker et al., 2007; García-España et al., 2004; Lively et al., 2015; Rosa et al., 2018; Stenhouse et al., 2009)coupled with the reduction of carbon dioxide emissions in the atmosphere, have been proposed.

In an early paper (Pastero et al., 2019), we proposed the ascorbic acid (vitamin C) as a high-performance and green CO2 scrubber. We hypothesized a red-ox reaction involving calcium ascorbate as the sacrificial reductant. As a result, the reduction of carbon from C(IV) to C(III) leads to the formation of oxalic acid and, in the presence of calcium as the counterion, to the precipitation of calcium oxalate. Calcium oxalate is an almost insoluble salt that doubles the capture efficiency with respect to calcium carbonate. The reaction’s performance in terms of carbon capture efficiency was evaluated under different experimental conditions. Depending on the experimental setup, the yield of the capture and sequestration reaction reaches very high values, up to 80%. The return of the system depends on the total surface exposed to the reaction, the CO2/vitamin C mixing mode, the presence of oxygen in the reaction vessel, and the stoichiometry of the solution.

The products of the reaction are limited to calcium oxalate dihydrate (weddellite), while no monohydrate (whewellite) or trihydrate (caoxite) oxalates were detected. The chemistry of the system was intentionally kept far from the stability field of the carbonates to avoid the co-precipitation of both calcium carbonate and oxalate and, accordingly, the competition between the two phases on the carbon capture process.

The technological finalization of a carbon capture system exploiting this reaction will trustfully increase further the effectiveness of the method, pointing towards the zero CO2 emission.

 

References

Aresta, M., Dibenedetto, A., 2007.  Dalt. Trans. 0, 2975. https://doi.org/10.1039/b700658f

Bachu, S., 2008.  Prog. Energy Combust. Sci. https://doi.org/10.1016/j.pecs.2007.10.001

Baker, J.M., Ochsner, T.E., Venterea, R.T., Griffis, T.J., 2007. Agric. Ecosyst. Environ. https://doi.org/10.1016/j.agee.2006.05.014

García-España, E., Gaviña, P., Latorre, J., Soriano, C., Verdejo, B., 2004.  J. Am. Chem. Soc. 126, 5082–5083. https://doi.org/10.1021/ja039577h

Lively, R.P., Sharma, P., Mccool, B.A., Beaudry-Losique, J., Luo, D., Thomas, V.M., Realff, M., Chance, R.R., 2015. Biofuels, Bioprod. Biorefining 9, 72–81. https://doi.org/10.1002/bbb.1505

Pastero, L., Curetti, N., Ortenzi, M.A., Schiavoni, M., Destefanis, E., Pavese, A., 2019. Sci. Total Environ. 666, 1232–1244. https://doi.org/10.1016/J.SCITOTENV.2019.02.114

Rosa, G.M. da, Morais, M.G. de, Costa, J.A.V., 2018. Bioresour. Technol. 261, 206–212. https://doi.org/10.1016/j.biortech.2018.04.007

Stenhouse, M., Arthur, R., Zhou, W., 2009. In: Energy Procedia. pp. 1895–1902. https://doi.org/10.1016/j.egypro.2009.01.247

How to cite: Pastero, L., Marengo, A., Bernasconi, D., Scarafia, G., and Pavese, A.: Vitamin C as a green high-performance CO2 scrubber, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20072, https://doi.org/10.5194/egusphere-egu2020-20072, 2020.

As climate change issues arise and become a global concern, to reduce carbon emissions has become an urgent issue to respond to. Therefore, the application of renewable energy plays more and more important roles in the energy domain nowadays, which may also bring significant impacts to the low-carbon electricity market transition. With the advantages of developing renewable energy, the Taiwan government anticipates achieving the goal of reaching 20% renewable energy in electricity structure by 2025. Moreover, Taiwan has carried out the most vigorous amendment on the Electricity Act in history to open the electricity market so that more stakeholders can participate in it to propel energy transition. Since the UK is the lead in this field, it is worth investigating. This paper takes the UK as a case study to analyze its evolution in recent decades after the deregulation of its electricity market from the retail side perspective. It expects to explore how the transition drove actors to empower their roles, or even create new roles and responsibilities, and engage in the low-carbon electricity market transition pathway. This paper expects the UK case as a great reference for Taiwan, which echoes the current scenario in Taiwan with the potential to deliver further insights.

How to cite: Lu, Y.-T. and Lin, T.-L.: Low-carbon Electricity Market Transition in the UK: A Multi-level Perspective Analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17841, https://doi.org/10.5194/egusphere-egu2020-17841, 2020.

EGU2020-9246 | Displays | ERE1.1

Estimating fuel consumption of cars based on movement data and its sensitivity to car and movement specific properties

Martin Pontius, Benedikt Gräler, Albert Remke, and Arne de Wall

The transportation sector is responsible for approximately 20 percent of global CO2 emissions of which most of them are produced by road traffic. Moreover, emissions are rising and are rising faster than in other sectors. Reducing these emissions will be crucial to reach the goals of the 2016 Paris agreement. Efficient reduction strategies and their monitoring rely on broad and exact data about passenger car fuel consumption and emissions.

To encourage people to drive eco-efficiently and to collect traffic data the open Citizen Science Platform enviroCar (https://enviroCar.org) had been initiated. Data from the internal vehicle's communication bus can be sent to the enviroCar Android App via an OBD-Bluetooth adapter and the data can be anonymised and uploaded as open data to the enviroCar server. Fuel consumption - and thus also emissions - are conventionally calculated from motor-specific data like mass-air-flow. One drawback of this approach is that users need to have an OBD adapter installed to get these specific data. An easier and broader use of the app is achieved by basing the calculation of energy consumption on movement data only which can be measured by GPS sensors in many mobile phones.

We present such a purely GPS-based approach and means to assess the sensitivity of the resulting fuel consumption to parameters of the vehicle and the movement pattern. The analyzed vehicles and track patterns show a high degree of heterogeneity regarding size and weight of vehicles and driven speed, acceleration and road gradient. In total, 51 tracks from the open enviroCar server covering 7600 km within 95 hours were analyzed.

The calculation is done using simple physical laws and is very lightweight, yet the fuel consumption values are relatively precise when compared to the OBD data based approach. The differences of fuel consumption per 100 km are typically below 1 l. Only for tracks which include a significant amount of stop-and-go characteristics, the observed discrepancies exceed 1 l.

The approach can also be adapted to electric cars as it is load-based. In this case, a recuperation model has to be included and the model to calculate efficiency has to be adapted.

How to cite: Pontius, M., Gräler, B., Remke, A., and de Wall, A.: Estimating fuel consumption of cars based on movement data and its sensitivity to car and movement specific properties, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9246, https://doi.org/10.5194/egusphere-egu2020-9246, 2020.

EGU2020-11727 | Displays | ERE1.1

ROBOMINERS - Resilient Bio-inspired Modular Robotic Miners

Balazs Bodo, Luis Lopes, Claudio Rossi, Giorgia Stasi, Stephen Henley, Vitor Correia, Tobias Pinkse, Alicja Kot-Niewiadomska, Jussi Aaltonen, Nikolaus Sifferlinger, Nelson Cristo, Norbert Zajzon, Gorazd Zibret, Janos Horvath, and Maarja Kruusma

The Horizon 2020 ROBOMINERS project (Grant No. 820971) studies the development of an innovative technology for the exploitation of small and difficult to access mineral deposits. A bio-inspired reconfigurable robot with a modular nature will be the target of the research efforts. The goal is to develop a prototype that will be able to mine under different conditions, such as underground, underwater or above water. ROBOMINERS’ innovative approach combines the creation of a new mining ecosystem with novel ideas from other sectors, particularly robotics. This covers both abandoned, currently flooded mines not accessible anymore for conventional mining techniques; or places that have formerly been explored, but whose exploitation was considered as uneconomic due to the small-size of deposits, or their difficulty to access. 

The ROBOMINERS concept follows a 5-step approach: 1) Robot parts (modules) are sent underground via a borehole; 2) Self-assemble to form a fully functional robot; 3) Robot detects the ore deposit via sensing devices; 4) Using ad-hoc production devices, it produces slurry that is pumped out; 5) Ability to re-configure on-the-job. 

Specifics include: 1) Construction of a fully functional modular robot miner prototype following a bioinspired design, capable of operating, navigating and performing selective mining; 2) Designing a mining ecosystem of expected future upstream/downstream raw materials processes via simulations, modelling and virtual prototyping; 3) Validation of all key functions of the robot-miner to a "Technology Readiness Level" of TRL4; and  4) To use the prototypes to study and advance future research challenges concerning scalability, resilience, re-configurability, self-repair, collective behavior, operation in harsh environments, selective mining, production methods, as well as for the necessary converging technologies on an overall mining ecosystem level. These specific goals will deliver a new mining concept, proven in laboratory conditions, capable of changing the scenario of mineral exploitation.

Powered by a water hydraulic drivetrain and artificial muscles, the robot will have high power density and environmentally safe operation. Situational awareness and sensing will be  provided by novel body sensors, such as artificial whiskers that will merge data in real-time with real-time production mineralogy  sensors that, together with specific production tools, will enable selective mining, optimising the rate of production and selection between different production methods. The produced mineral concentrate slurry is pumped to the surface, where it will be processed. The waste slurry could then be returned to the mine where it will backfill mined-out areas.

ROBOMINERS will deliver proof of concept for the feasibility of this technology line, which can enable the EU to have access to mineral raw materials from otherwise inaccessible or uneconomic domestic sources, decreasing European dependency on imports from third-party sources, as envisaged by the raw materials policy. Laboratory experiments will confirm the Miner’s key functions, such as modularity, configurability, selective mining ability, and resilience under a range of operating scenarios. The Prototype Miner will then be used to study and advance future research challenges concerning scalability, swarming behaviour and operation in harsh environments.

How to cite: Bodo, B., Lopes, L., Rossi, C., Stasi, G., Henley, S., Correia, V., Pinkse, T., Kot-Niewiadomska, A., Aaltonen, J., Sifferlinger, N., Cristo, N., Zajzon, N., Zibret, G., Horvath, J., and Kruusma, M.: ROBOMINERS - Resilient Bio-inspired Modular Robotic Miners, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11727, https://doi.org/10.5194/egusphere-egu2020-11727, 2020.

EGU2020-6140 | Displays | ERE1.1

The potential of detecting flaws in an experimental dam at Älvkarleby, Sweden, using P-wave traveltime tomography

Silvia Salas-Romero, Christopher Juhlin, and Christian Bernstone

A large number of dams located in Sweden, built in the second half of 20th century, are earth embankment dams. Seepages and internal erosion represent safety issues, which are difficult to detect and predict. There are indirect methods to detect seepages, but these do not provide their location. The hydropower operator Vattenfall has initiated a research project to assess geophysical methods as a decision support and asset management tool for this type of structure. The project consists of detecting built-in flaws in the core of a 20 m long and 4 m high experimental dam using geophysical (seismic and resistivity) and temperature measurements taken at the top of and inside the dam structure for a period of approximately 18 months. The behaviour of the dam itself will be monitored by geotechnical instrumentation.

This work focuses on testing P-wave traveltime tomography for detecting defects and supporting the interpretation of P-wave reflection seismic data. Synthetic traveltime studies were performed using the dam structure, constant P-wave velocities for each material, and the seismic acquisition design. Five parallel lines of hydrophones were used, three at the top and two at the bottom of the dam. The central hydrophone line at the top of the dam coincides with the position of the seismic sources. In addition, four boreholes to 4 m depth are positioned on each side of the central hydrophone line in both edges of the dam. Within these boreholes shots and receivers were positioned at every 0.5 m depth. The initial velocity model of the dam considers that the dam is filled with water up to a height of 3.5 m. A series of defects (low velocity zones with varying size and position) were inserted. Other factors, like noise or error in the acquisition geometry, were also considered. The defects may be cavities or permeable/loose layers.

Preliminary results show, in general, that the defect position can be identified by tomography. The velocity and size of the defects, however, are not well recovered by the method. Recovery of the defects using traveltime tomography is greatly influenced by the defect position, as the seismic ray coverage is limited in some parts, such as the central lower part of the dam. In the case of a defect located closer to the top hydrophone lines or one of larger size, the anomalies are better identified. We note that the amplitudes of the anomalies are very small, which may complicate identifying defects using real data. The anomaly signatures depend on the shape of the defect, for example a cubic defect compared to a horizontal permeable layer, which could help to identify and characterize the defect. Although the primary focus lies on identifying the presence of defects, information about their dimension and type is also important.

Future work will be focused on processing repeated seismic fieldwork campaigns at the experimental dam, in order to investigate the dam integrity using time-lapse seismic measurements, including comparing the seismic data with other types of data.

How to cite: Salas-Romero, S., Juhlin, C., and Bernstone, C.: The potential of detecting flaws in an experimental dam at Älvkarleby, Sweden, using P-wave traveltime tomography, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6140, https://doi.org/10.5194/egusphere-egu2020-6140, 2020.

EGU2020-4585 | Displays | ERE1.1

Mapping urban changes of 31 global-mega cities using VIIRS nighttime light time series

Qiming Zheng, Ke Wang, and Qihao Weng

People’s perception of ecosystem services is usually affected by a variety of interacting factors, making it difficult to identify the actual driving factors. An orthogonal experimental design can effectively identify interactions and has the potential for use in social perception studies. Based on 20,642 questionnaires on the topic of WTP (willingness to pay), the interactive forces driving people’s perceptions of ecosystem services on the Tibetan Plateau were identified using an orthogonal experimental design. The results show that 1) when interactions are not considered, management attitudes have the strongest influence on WTP, the second most influential factors are subjective cognitions, and objective indicators are ranked last. 2) The interactions has a stronger impact on WTP than some of individual factor: when interactions and observed variables are compared simultaneously, the interaction between the “importance of the Tibetan Plateau” and the “WTP for residents” has a stronger influence on WTP (451 Chinese yuan/year) than any of the individual variables except “WTP for residents” (666 CNY/year) and “knowledge of the Tibetan Plateau” (484 CNY/year). Among the interactions between pairs of variables, that between education (212 CNY/year) and income (260 CNY/year) has a greater impact on WTP (266 CNY/year) than either variable alone. 3) When the interactions are considered, subjective cognitions are the most important indicators for WTP, and management attitudes are the second most important indicators. This study provides a feasible method for the identification of interactive driving forces in analyses involving questionnaires, and the conclusions can provide guidance from the public for ecosystem management on the Tibetan Plateau.

How to cite: Zhang, R.: The application of orthogonal experimental design to identify the interactive forces driving people’s perceptions of ecosystem services, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4447, https://doi.org/10.5194/egusphere-egu2020-4447, 2020.

With the increase of global temperature and the intensification of human activities, numerous ecological problems have occurred in the grasslands of Inner Mongolia, which have seriously disturbed the sustainable development and the improvement of the carrying capacity of grassland ecosystems, and threatened the security of regional ecological environment. There is an urgent need to find a quantitative assessment method for the quantification of  the carrying capacity in grassland ecosystems, which is significantly crucial for making a sustainable development strategies of  grassland resources. In this study, we considered the ecosystem services as a limited well-beings, and took the Net Primary Production (NPP) as the core indicator for characterizing the occupation of grassland's main ecological functions to ecosystem services. Further more, the occupy threshold for environment maintenance and natural regeneration functions were calculated. The spatial distribution of the grasslands carrying capacity in Inner Mongolia was quantitatively analyzed, and the vulnerability of the "human-land system" was evaluated. The results show that: (1) The Above-ground Net Primary Production (ANPP) needed for the ecosystem function maintenance of Inner Mongolia in 2015 was at 38-401 g/m²· a, and there was a decreasing trend from northeast to southwest; (2) In 2015, the ecological carrying capacity of the grassland ecosystem in Inner Mongolia was 79.336 million sheep units, and the average carrying capacity was 1.56 sheep unit / hm² • a. However, the total economic carrying capacity was 174,571 million sheep units, and the average economic carrying capacity was 3.42 sheep unit / hm² • a, whose spatial distribution is basically consistent with the spatial distribution of ecological carrying capacity, while the actual stocking was 145,548 million sheep units. (3) The spatial distribution of the grassland carrying capacity displayed highly spatial heterogeneity in Inner Mongolia. The ecological carrying status index ranged from 0.59 to 12.06, and the economic carrying status index ranged from 0.29 to 3.68. The natural regeneration function of grasslands required the largest NPP, which greatly reduced the grassland ecological carrying capacity in Inner Mongolia. From the perspective of spatial distribution, the ecological carrying capacity of grassland in eastern Inner Mongolia is bigger than that of western region, and there was an imbalance between socioeconomic development and ecological environmental maintenance. The concentration of population in eastern Inner Mongolia is the main limiting factor affecting the ecological carrying capacity, which resulting in the supply of grassland ecological system cannot meet the practical needs of social development. The environment western characterized by the water deficient and low vegetation coverage were the main limiting factors of ecological carrying capacity in western Inner Mongolia, where the grassland function of windbreak and sand-fixation needed to take up more resources.

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How to cite: caiyun, G. and dongsheng, Z.: Analysis of grassland carrying capacity in Inner Mongolia based on ecosystem function, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13509, https://doi.org/10.5194/egusphere-egu2020-13509, 2020.

EGU2020-3002 | Displays | ERE1.1

Spatiotemporal Change Analysis of of Water, Energy and Food Resources in Yellow River Basin

Liming Ma, Chaoqun Li, Xiaoyan Hu, Peng Wang, and Xiao Li

The Yellow River Basin is rich in land, energy, and mineral resources, which is an important energy base and major food producing area in China. However, water shortages have become a key factor restricting the development of the basin. With the economic and social development and population growth, resources demand of water, food and energy in the river basin has been further increased under the drive of national energy security and food security strategies. The conflict between resource supply and demand has become more prominent. This paper selected 9 provinces of the Yellow River Basin as the study area, and collected 16-year time series data, and quantitatively describes the temporal and spatial coordinated changes of water, energy, and food through methods such as MK test and synergetic evaluation system. The results show that in the nine provinces of the Yellow River Basin, the water supply has increased slightly, and energy and food production have increased significantly. The spatial differences of water supply and food production have little change and are relatively stable, while the change of spatial differences in energy production are more obvious with a downward trend, indicating that regionalization of energy production areas is becoming more and more obvious. According to the synergetic evaluation system, the coefficients of synergy for all of the nine provinces are gradually increasing. The evaluation coefficient of Henan is relatively high, indicating that Henan has a positive synergy of water, energy, and food resources. And the Ningxia province has the lowest evaluation coefficient. According to the results, the water energy and food system reconfiguration should be carried out for key provinces, and the allocation of water energy and food resources should be optimized to maximize the utilization of the three resources and achieve sustainable use.First of all, adjusting the energy structure among the provinces with poor synergy. For example, raw coal is still the core resource of energy consumption which is water-intensive. Reduce the investment in coal chemical industry and other high water-consumed energy industry to have a better synergy coefficient. Also, develop more clean energy, for example, hydro-power, nuclear power and wind power. Nowadays, the environment-friendly and resource-saving clean energy portion is less than 10% of the total energy consumption. The waste resources can be reuse to provide green energy. Last, high-end production technology in energy production is important to guarantee the water and energy safety. 

How to cite: Ma, L., Li, C., Hu, X., Wang, P., and Li, X.: Spatiotemporal Change Analysis of of Water, Energy and Food Resources in Yellow River Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3002, https://doi.org/10.5194/egusphere-egu2020-3002, 2020.

This research provides an overview on several areas related to produced water management including cost, treatment methods, recycling options and environmental impact. Produced water is a type of water that has been trapped in different quantities in underground formations. After extracting crude oil and during the production process, the associated water from underground formations is known as produced water. This type of water is by far the largest volume by product or waste stream associated with oil and gas production. It is likely containing high level of total dissolved solids because of its longer residence time under the ground in addition to the smaller flow rate. Moreover, many efforts have been paid globally to decrease the high salinity level in produced water by applying desalination technologies as sustainable water management solution.

Oilfield water management is one of the most challenging system and it follows a non-linear relationship between its components. We formulate and develop a mixed-integer mathematical model to a small case study related to Kuwait Oil Company for an optimal design and operations of produced water management. We show how the results allow studying the economic cost as well as environmental impact related to produced water management system.

 

 

How to cite: AlEdan, A. and Erfani, T.: Produced water management - A mathematical model to trade-off economic cost and environmental impact for infrastructure utilisation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20912, https://doi.org/10.5194/egusphere-egu2020-20912, 2020.

Bacteria capable of simultaneous aerobic denitrification and phosphorus removal (SADPR) are promising for the establishment of novel one-stage wastewater treatment systems. Nevertheless, insights into the metabolic potentials and engineered applications of SADPR-related bacteria are limited. Firstly, comprehensive metabolic models of two efficient SADPR bacteria, Achromobacter sp. GAD3 and Agrobacterium sp. LAD9, were obtained by high-throughput genome sequencing. With succinate as the preferred carbon source, both strains employed a complete TCA cycle as the major carbon metabolism for potentials of various organic acids and complex carbon oxidation. Complete and truncated aerobic denitrification routes were confirmed in GAD3 and LAD9, respectively, facilitated by all the major components of the electron transfer chain via oxidative phosphorylation. Comparative genome analysis revealed distinctive ecological niches involved in denitrification among different phylogenetic clades within Achromobacter and Agrobacterium. Excellent phosphorus removal capacities were contributed by inorganic phosphate uptake, polyphosphate synthesis and phosphonate metabolism. Additionally, the physiology of GAD3/LAD9 is different from that displayed by most available polyphosphate accumulating organisms, and reveals both strains to be more versatile, carrying out potentials for diverse organics degradation and outstanding SADPR capacity within a single organism. Secondly, both GAD3 and LAD9 were successfully applied for bioaugmented treatment of municipal wastewater in a pilot-scale sequencing batch reactor. At an appropriate COD/N ratio of 8, the bioaugmentation system exhibited stable and excellent carbon and nutrients removal, the averaged effluent concentrations of COD, NH4+-N, TN and TP were 20.6, 0.69, 14.1 and 0.40 mg/L, respectively, which could meet the first class requirement of the National Municipal Wastewater Discharge Standards of China (COD < 50 mg/L, TN < 15 mg/L, TP < 0.5 mg/L). Clone library and real-time polymerase chain reaction analysis revealed that the introduced bacteria greatly improved the structure of original microbial community and facilitated their aerobic nutrients removal capacities. This proposed emerging technology was shown to be an alternative technology to establish new wastewater treatment systems and upgrade or retrofit conventional systems from secondary-level to tertiary-level.

How to cite: Liu, S., Chen, Q., Liu, S., and Ni, J.: Comprehensive insights into metabolic potentials and engineered applications of two novel simultaneous aerobic denitrification and phosphorus removal bacteria, Achromobacter sp. GAD3 and Agrobacterium sp. LAD9, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3221, https://doi.org/10.5194/egusphere-egu2020-3221, 2020.

EGU2020-19982 | Displays | ERE1.1

Beach wrack as a potential natural resource in the South-Eastern Baltic

Julia Gorbunova and Boris Chubarenko

Beach wrack (BW) – biological marine materials as algae, sea grasses and other, which are thrown from the sea to the seashore, becoming a polluter and cause of inconvenience. Problem of BW is present in the Kaliningrad Oblast of Russia, South-Eastern Baltic. From time to time, large amounts of BW appear in various places along its seashore. However, BW can be used as an organic resource, so nuisance could be converted into resource and asset. The study on BW spatial and quantitative distribution and its potential use in the South-Eastern Baltic is carry out within the Project #R090 CONTRA of the Interreg Baltic Sea Region Programme and accompanied by researches of algae species composition basing on partly support of the State assignment of IO RAS (Theme No. 0149-2019-0013).

An observations of the Baltic seashore within the Kaliningrad Oblast was carried out in March-December 2019 with the aim of quantity and quality characteristic of BW emissions. The BW emissions were recorded (measured, described and geo-referenced using GPS navigation) and sampled on two model sites monthly and the alongshore survey was carried out seasonally. Monitoring of the time of residence of the BW emissions was carried out three times per day at the selected model site using a web camera. It was found that the distribution of BW was characterized by significant spatial and temporal variability. In general, large amounts of BW emissions were observed on the northern coast of the Sambian Peninsula, in contrast to the western coast and Curonian and Vistula spits. The largest accumulations of BW were local and mainly near the coastline protrusions as capes (natural) and breakwaters, slipways, bunes (man-made). The time of residence of BW storage varied greatly and was often limited to a few days. Their further transformation could be carried out in several ways - by flushing back to the sea, covering under the thickness of sand or small pebbles, and a wind-wave dispersal along the beach. BW mainly contains Radophyta algae in the early spring and autumn-winter periods, in contrast to summer, when there are also Chlorophyta and Phaeophyta.

The preliminary estimations show that the industrial use of BW is limited by the spatial and temporal irregularity of their emissions in the Kaliningrad Oblast. However, the problem of BW collection and utilization exists. A possible solution could be use of BW for coastal protection greenery as nutrients that is similar to a natural process. These experiments were initiated in the Curonian Spit National Park in 2019. In this way BW could be involved in soft engineering techniques to manage the coastline.

How to cite: Gorbunova, J. and Chubarenko, B.: Beach wrack as a potential natural resource in the South-Eastern Baltic, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19982, https://doi.org/10.5194/egusphere-egu2020-19982, 2020.

Recently, several alkylamine hydrates have been studied in an effort to reveal the structural transitions from semi- to ‘canonical’ clathrate hydrate in the presence of secondary guest molecules. Trimethylamine (TMA) is known to form the semi-clathrate hydrate, and it has been reported that the structural transition of the TMA semi-clathrate hydrate may not occur in the presence of hydrogen gas as a secondary guest molecule. This paper reports the structural transition of trimethylamine(TMA) hydrate induced by the type of guest molecules. Powder X-ray diffraction patterns of (TMA + H2) hydrates show the formation of hexagoanl P6/mmm hydrate, but those of (TMA + CH4) hydrates indicate the formation of cubic Fd3m hydrate. Without gaseous guest molecule, the crystal structure of pure TMA hydrate is identified as hexagonal P6/mmm. Therefore, inclusion of gaseous methane in TMA hydrate can induce the structural transition from hexagonal to cubic hydrate or the formation of metastable cubic hydrate. To clearly reveal this possibility, we also check the time-dependent structural patterns of binary (TMA + CH4) hydrates from 1 to 14 days, and the results show that the structural transition of TMA hydrate from hexagonal P6/mmm to cubic Fd3m hydrate structure can occur during the methane inclusion process.

How to cite: Cha, M.: Structural Transition of Trimethylamine Hydrate by Methane or Hydrogen Inclusion, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3806, https://doi.org/10.5194/egusphere-egu2020-3806, 2020.

ERE1.2 – GeoERA: Towards integrated European geoscience services for today’s and future generations

The IPCC and IPBES reports, the sustainable development goals of the United Nations and the societal challenges for Europe defined by Horizon 2020 and Horizon Europe all emphasize the strong need for integrated and sustainable management of subsurface resources to protect society and biodiversity. The four GeoERA groundwater projects contribute to this important goal by studying the current and future quantitative and chemical status of European groundwater bodies. The quantity and quality issues related to natural processes, human activities and climate change are investigated to improve our basis for informed decision making e.g. for climate change mitigation and adaptation. The four projects provide new and important data for further development of the European Geological Data Infrastructure (EGDI) as a leading information platform for sustainable and integrated management of subsurface resources in Europe and one of the leading platforms, globally. The four projects will deliver “FAIR” (Findable, Accessible, Interoperable and Reusable) data easily accessible for all relevant end users via EGDI. This will improve our understanding of the subsurface and support common efforts in public-private partnerships to meet the UN sustainable development goals and to develop efficient tools for climate change impact assessment, mitigation and adaptation. Here we briefly present some main objectives and deliverables of the four groundwater projects: 1) HOVER – “Hydrogeological processes and geological settings over Europe controlling dissolved geogenic and anthropogenic elements in groundwater of relevance to human health and the status of dependent ecosystems” – studies e.g. I) geogenic (natural) groundwater quality issues affecting human health, II) polluted groundwater focusing on nitrate, pesticides and emerging contaminants that besides human health potentially affect biodiversity and the ecological status of terrestrial and aquatic ecosystems and III) groundwater age and travel time distributions in European aquifers, which are useful for assessment of the history, migration and fate of contaminants in the subsurface and the vulnerability of the European groundwater resources towards pollution 2) RESOURCE – “Resources of groundwater, harmonized at cross-border and Pan-European Scale” – studies I) transboundary aquifers between Poland and Lithuania; as well as Belgium, The Netherlands and Germany; II) Karst and Chalk aquifers across Europe and III) Develops a new Pan European groundwater resources map that includes information on volumes, age and quality (salinity) 3) TACTIC – “Tools for assessment of climate change impact on groundwater and adaptation strategies” – compiles and studies climate change impact assessment and adaptation tools within more than 40 pilot areas distributed across Europe and 4) VoGERA –  “Vulnerability of shallow groundwater resources to deep sub-surface energy-related activities” – studies groundwater vulnerability to energy-related activities in the UK, the Netherlands, Belgium and Hungary.

How to cite: Hinsby, K., Gourcy, L., Broers, H. P., Højberg, A. L., and Bianchi, M.: Integrated and sustainable management of subsurface resources - Introducing the contributions of the four GeoERA groundwater projects to the European Geological Data Infrastructure , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4253, https://doi.org/10.5194/egusphere-egu2020-4253, 2020.

EGU2020-17309 | Displays | ERE1.2

Minerals Inventory as a part of Mineral Intelligence for Europe

Špela Kumelj, Andrej Vihtelič, Katarina Hribernik, and Jernej Bavdek

A significant task of the Mintell4EU project is to improve the quality and spatial coverage of the European inventory of primary and secondary mineral resources. The process of refining the minerals inventory that is currently within the Minerals4EU (M4EU) database includes (a) identification of data gaps in spatial coverage, (b) setting up the quality control application to identify gaps and errors in data, (c) identification of technical errors in the process of harvesting data and (d) establishing connections with other relevant projects.

After almost 2 years, the spatial coverage of the minerals inventory is extended with data from Western Balkan countries in cooperation with the RESEERVE project and new or modified data from existing data providers are available. Besides, a Mintell4EU Quality Control Application (QCA) was developed to visually check the latest reported data from data providers. Related to this, a harvesting system for collecting and validating mineral resources data is being established and improved access to raw materials data technical routines intervening during the harvesting phase are being implemented to ensure a rigorous control of the data quality.

The subsequent task is to enable new data providers to deliver data in a harmonized way to ensure consistency in the way data is displayed. In order to achieve this in the best way possible, a workshop will be held in Ljubljana in May 2020, drawing on experiences from REESERVE and from guidelines developed by the ORAMA project.

How to cite: Kumelj, Š., Vihtelič, A., Hribernik, K., and Bavdek, J.: Minerals Inventory as a part of Mineral Intelligence for Europe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17309, https://doi.org/10.5194/egusphere-egu2020-17309, 2020.

EGU2020-21081 | Displays | ERE1.2

Structural framework: a new way to organise and communicate geological information

Kris Piessens, Renata Barros, Katrijn Dirix, Jef Deckers, Johan ten Veen, Timothy N. Debacker, and Fabian Jähne-Klingberg

A structural framework is a well-defined concept, being used primarily to add structural understanding to a geological model. Within GeoConnect³d, a new approach is used, i.e. the structural framework concept is modified to become the leading model, in which geological maps and models can be inserted and related to. This structural framework is being developed and implemented for two areas of interest - Roer-to-Rhine in northwest Europe and Pannonian Basin in eastern Europe - and will soon be implemented in two pilot areas, Ireland and Bavaria. The organisation of information is strongly linked to different scales of visualisation, starting from the pan-European view (1:15,000,000) with the possibility to zoom in to the scale of local geological models and maps in these four areas.

The GeoConnect³d structural framework reorganises geological information in terms of geological limits and geological units. Limits are defined as broadly planar structures that separate a given geological unit from its neighbouring units, e.g. faults (limits) that define a graben (unit), or an unconformity (limit) that defines a basin (unit). Therefore, the key relationship between these two structural framework elements is that units are defined by limits i.e. all units must be bounded by limits. It is important to note that this relationship is not necessarily mutual: not all limits have to be unit-defining.

A first test of the structural framework methodology was carried out in the Netherlands and Belgium for the Roer Valley graben, as the faults in this area were already modelled in a cross-boundary project (H3O-Roer Valley Graben). Displaying different elements according to scale of visualisation coupled with vocabulary information (definition, grouping and semantic relations between elements, etc.) following the SKOS-system proved a powerful tool to display geological information in an understandable way and improve insights in large-scale geological structures crossing national borders. Additionally, links with other GeoERA projects such as HIKE and its fault database are being successfully established. We consider the outcomes of this test promising to fulfil one of the main goals of GeoConnect³d, i.e. preparing and disclosing geological information in an understandable way for stakeholders. We also consider this as the way forward towards pan-European integration and harmonisation of geological information, where the ultimate challenge is to correlate or otherwise link information from different geological domains and of different scales.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166.

How to cite: Piessens, K., Barros, R., Dirix, K., Deckers, J., ten Veen, J., Debacker, T. N., and Jähne-Klingberg, F.: Structural framework: a new way to organise and communicate geological information, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21081, https://doi.org/10.5194/egusphere-egu2020-21081, 2020.

EGU2020-3510 | Displays | ERE1.2

GeoERA MUSE – Managing Urban Shallow Geothermal Energy

Cornelia Steiner, Stasa Borovic, Alejandro García-Gil, Claus Ditlefsen, David Boon, Ignasi Herms, Camille Maurel, Estelle Petitclerc, Mitja Janza, Mikael Erlström, Maciej Klonowski, Jan Holeček, Sarah Blake, Vincent Vandeweijer, Radovan Cernak, and Boris Maljuk

The shallow subsurface comprising groundwater bodies as well as solid rock formations in the uppermost tens to hundreds of meters below surface offer significant resources for renewable heating, cooling and seasonal underground heat storage. Shallow geothermal energy (SGE) comprises the technologies to exchange heat between the subsurface and surface via closed loop or open loop heat exchangers. Although SGE just covered around 2% of the renewable heat production in the EU in 2018, its huge potential for low temperature heating and cooling supply is expected to lead to a significant market growth across Europe in the upcoming decade. Especially as SGE offers the unique possibility to supply heating, cooling and storing waste heat with one technology. SGE offers advantages especially in urban areas. It does not produce waste heat if applied for cooling, which can be considered as an important measure to mitigate urban heat islands. It consumes low amount of surface space for its installation and applying SGE is free of emissions in terms of aerosols or noise. Moreover, it can be combined with other renewables such as solar and waste heat or excess energy. In these cases, SGE acts as a seasonal heat storage.

The increasing interest in SGE in urban areas, however, puts pressure on the subsurface, especially on shallow groundwater bodies. In that context, SGE systems may compete with each other as well as with water supply and subsurface installations. In many European countries, management approaches of SGE are either lacking or follow the first come first serve approach. Integrative management approaches follow an information and decision cycle, starting and ending at collecting, processing and providing geoscientific data on subsurface conditions to stakeholders, such as authorities, investors and city planners.

GeoERA MUSE addresses integrative management approaches for the use of SGE by harmonizing concepts and testing them in 14 European cities facing different climatic, hydrogeologic and socio-economic boundary conditions. MUSE deals with mapping resources and limitations of SGE resources and displays them in modern web-based interfaces. Knowing resources and limitations referring to interference with other SGE systems or other shallow subsurface installations is the starting point for integrative management approaches, which include summation effects and abandon first come first serve. MUSE pilot areas follow the whole management cycle from creating subsurface data (e.g. subsurface temperatures, thermal rock properties), deriving resource models (amount of energy available for use), limitations of use (contaminated areas, problematic chemical composition of groundwater) and displaying the information gained at the EGDI web platform of EuroGeoSurveys. Furthermore, MUSE interacts with local stakeholders to transfer geoscientific data models into managing strategies. In that sense, the pilot areas act as role model for other urban regions in Europe. Additionally, MUSE creates joint concepts and standards to strengthen the role of Geological Survey Organisations towards a key player in managing an efficient and sustainable use of urban subsurface in general and SGE in urban areas in detail. MUSE has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166.      

How to cite: Steiner, C., Borovic, S., García-Gil, A., Ditlefsen, C., Boon, D., Herms, I., Maurel, C., Petitclerc, E., Janza, M., Erlström, M., Klonowski, M., Holeček, J., Blake, S., Vandeweijer, V., Cernak, R., and Maljuk, B.: GeoERA MUSE – Managing Urban Shallow Geothermal Energy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3510, https://doi.org/10.5194/egusphere-egu2020-3510, 2020.

EGU2020-5950 | Displays | ERE1.2 | Highlight

FRAME’s (Forecasting and Assessing Europe’s Strategic Raw Materials Needs) contribution to the “European Green Deal”

Daniel P. S. de Oliveira, Maria João Ferreira, Martiya Sadeghi, Nikolaus Arvanitidis, Sophie Decrée, Håvard Gautneb, Eric Gloaguen, Tuomo Törmänen, Helge Reginiussen, Henrike Sievers, Lídia Quental Quental, and Antje Wittenberg

It is widely accepted that non-energy minerals underpin modern economies since they are essential for manufacturing and renewable energy supply. Europe shows an inevitably growing and accelerated consumption of mineral commodities. The critical question is whether supply to meet these demands is adequate. However, no one can answer this with any certainty because secure supply of mineral RM is a matter of knowing the resources and the ability to exploit them sustainably.

Europe’s strive to be become the world’s first climate-neutral continent by 2050 means implementing the “European Green Deal” by the EU Commission. Measures accompanied with an initial roadmap of key policies range from ambitiously cutting emissions, to investing in cutting-edge research and innovation, to preserving Europe’s natural environment.

This green transition is a giant societal leap. However, of the clean and carbon-reducing technologies (e.g. wind turbines, photovoltaic panels, electric and hybrid vehicles), which allow energy production from renewable resources, use significant quantities of metals [e.g. REE, PGE, Nb, Li, Co, In, Ga, V, Te, Se] that are derived or refined from minerals, and of which Europe is strongly import dependent on. The high import dependence of strategic (SRM) and critical raw materials (CRM) has a serious impact on the sustainability of the EU manufacturing industry value chains and key enabling technologies (e.g. renewable energy industry, mobility sector and AI) and significant release of CO2 emissions due to foreign ore transport. Effectively knowing Europe’s subsurface and the potential mineral supplies that can be used in these manufacturing industries can achieve this. We need to calculate the volumes of CRM and SRM metals (e.g. Co, Nb, V, Sb, PGE and REE) and minerals currently not extracted in Europe. We further need to understand how high-tech elements are mobilised, where they occur and why some are associated with specific major industrial metals. This means a renewed and robust focus on advanced exploration for new mineral deposits on land and sea.

FRAME(*)[1] addresses most of these concerns by focusing on at least four of the current objectives of the EU Commission: 1- CRM; 2- battery critical elements [graphite, Co, Li]; 3- The circular economy and; 4- the responsible sourcing of metals by combating conflict minerals.

With focused work packages, FRAME aims to broadly deliver, 1- a new assessment of the SRM and CRM in Europe; 2- an innovative predictability of where the sourcing of some of these SRM and CRM may come from to reduce dependance on external supply sources, which in some specific metals such as Nb and Ta, fosters the sustainable and responsible supply and; 3- look at case specific sites for the reuse of mineral RM. Data will be made available through a structured data platform. Hence, FRAME is making a significant contribution to aid in the “European Green Deal”, activities such as the Battery Alliance and support legal actions like the new EU "conflict minerals" regulation effective from 1/01/2021.


[1] (*) This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement Nº 731166

 

How to cite: de Oliveira, D. P. S., Ferreira, M. J., Sadeghi, M., Arvanitidis, N., Decrée, S., Gautneb, H., Gloaguen, E., Törmänen, T., Reginiussen, H., Sievers, H., Quental, L. Q., and Wittenberg, A.: FRAME’s (Forecasting and Assessing Europe’s Strategic Raw Materials Needs) contribution to the “European Green Deal” , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5950, https://doi.org/10.5194/egusphere-egu2020-5950, 2020.

EGU2020-13271 | Displays | ERE1.2

Critical minerals in the European seas: The project GeoERA-MINDeSEA

Javier Gonzalez, Teresa Medialdea, Henrik Schiellerup, Irene Zananiri, Pedro Ferreira, Luis Somoza, Xavier Monteys, Thomas Kuhn, Johan Nyberg, Igor Melnyk, Vitor Magalhaes, Rosario Lunar, Egidio Marino, James R. Hein, Georgy Cherkashov, and MINDeSEA team

The oceans and seas cover more than 70% of the planet, representing a promising new frontier for mineral resources exploration, and an enormous challenge for science and technology. Communities are demanding actions to address global climate change, and the necessary high- and green-technologies required for a transition from a carbon-based to green-energy-based world. The global ocean is at the core of these issues. The seabed mineral resources host the largest reserves on Earth for some critical metals like cobalt, tellurium, manganese, and the rare earth elements, critical for Industry. But seabed geology and ecosystems are widely unexplored, and new geological and environmental studies are required to address the impacts of potential mining activities. In addition, a regulatory framework for minerals extraction and marine spatial planning are necessary for seabed mining sector development.

The pan-European seas cover about 15 millions square kilometres in the Arctic and Atlantic oceans and the Mediterranean, Baltic, and Black seas, from shallow waters up to 6000 m water depth. Spanning a large diversity of environments and resource settings, including high and low temperature hydrothermal deposits, phosphorites, cobalt-rich ferromanganese crusts, and manganese nodules, deep-sea deposits are particularly attractive for their polymetallic nature with high contents of rare and critical metals. Moreover, shallow-water resources, like marine placer deposits, represent another source for many critical metals and gems. The GeoERA-MINDeSEA[1]  project is compiling data and genetic models for all these deposit types based on extensive studies, carried out previously, which include geophysical surveys, dredging stations, underwater photography and ROV surveys, and mineralogical, geochemical, and isotopic studies.

The preliminary MINDeSEA results show the potential of the pan-European seas for critical metals, and the enormous gaps of information covering vast marine sectors. More than 600 mineral occurrences are reported in the MINDeSEA database. Seamounts and banks in the Macaronesia sector (Portugal and Spain) and the Arctic ridges (Norway, Denmark, Iceland) show a high potential for Fe-Mn crusts, rich in energy-critical elements like Co but also Te, REEs, and Mn. Fe-Mn crusts are accompanied by phosphorites on the seafloor of continental shelves and slopes along the western continental margins. Seafloor polymetallic sulphides and metalliferous sediments precipitating from hot hydrothermal solutions and plumes are forming today in the Azores Islands (Portugal), the Arctic (Norway, Denmark) and, the Mediterranean volcanic arcs (Italy and Greece). They are among the most important marine resources for Cu, Zn, Ag, and Au. In addition, hydrothermal deposits may contain economic grades of Co, Sn, Ba, In, Bi, Te, Ga, and Ge. Placer deposits of chemically resistant and durable minerals have been discovered on shallow-water settings (<50 m water depth on estuaries, deltas, beaches) linked to the weathering of onshore rocks and ore deposits from the Variscan Belt (UK, France, Portugal, Spain). Finally, shallow-water concretions and nodules from the Arctic, Baltic, and Black Sea represent potential targets for metals exploration and environmental studies.


[1] This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166

 

How to cite: Gonzalez, J., Medialdea, T., Schiellerup, H., Zananiri, I., Ferreira, P., Somoza, L., Monteys, X., Kuhn, T., Nyberg, J., Melnyk, I., Magalhaes, V., Lunar, R., Marino, E., Hein, J. R., Cherkashov, G., and team, M.: Critical minerals in the European seas: The project GeoERA-MINDeSEA , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13271, https://doi.org/10.5194/egusphere-egu2020-13271, 2020.

EGU2020-6656 | Displays | ERE1.2 | Highlight

Utilising data and knowledge from European geological survey organisations in climate change impact assessments and adaptations

Anker Lajer Hojberg, Ida Bjørnholt Karlsson, Klaus Hinsby, Jacob Kidmose, Hélène Bessiere, Majdi Mansour, and David Pulido-Velázquez

Climate change (CC) already have widespread and significant impacts in Europe, which is expected to increase in the future. Groundwater plays a vital role for the land phase of the freshwater cycle and have the capability of buffering or enhancing the impact from extreme climate events causing droughts or floods, depending on the subsurface properties and the status of the system (dry/wet) prior to the climate event. Understanding and taking the hydrogeology into account is therefore essential in the assessment of climate change impacts.

The Geological Survey Organisations (GSOs) in Europe compile the necessary data and knowledge of the groundwater systems across Europe. The overall vision of the project “Tools for Assessment of ClimaTe change ImpacT on Groundwater and Adaptation Strategies – TACTIC” is to enhance the utilisation of these data and knowledge of the subsurface system in CC impact assessments, and the identification and analyses of potential adaptation strategies. To reach this vision, the objective of TACTIC is to contribute to the development of coherent and transparent assessments of CC impacts on groundwater and surface water, supporting improved EU policy making, and providing decision support for stakeholders and decision makers. To accomplish this, an infra-structure among European Geological Survey Organisations are developed in TACTIC to foster advancement and harmonisation of CC assessments, made up by: 1) The TACTIC Toolbox, consisting of relevant tools and methods for CC impact assessments, 2) TACTIC guidelines that will guide GSOs and other relevant stakeholders on the selection of appropriate tools and their use for producing comparable results, 3) The European Geological Data Infrastructure (EGDI) where data, reports and open-access papers will be stored  and made freely available  

The project is centred around 40 pilot studies covering a variety of CC challenges as well as different hydrogeological settings and different management systems found in Europe. The pilot activities are coordinated centrally in the project, to ensure that assessments, to the extent possible, are harmonised and can be compared across pilots. Synthesizing the experiences and results from the pilots will enable the development of a guideline and future roadmap, with the aim of 1) encouraging more GSOs to contribute in CC impact assessments 2) providing guidance to make the learning curve less steep and 3)ensuring that new assessments are comparable with assessments conducted in TACTIC.

TACTIC is part of the Horizon 2020 ERA-NET on Applied Geoscience (GeoERA) and together with the three other GeoERA groundwater projects, TACTIC will provide new and important data for further development of the European Geological Data Infrastructure (EGDI) with publicly available data enabling the development of EU-wide decision support systems for sustainable management of subsurface resources in a changing climate.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166.

How to cite: Hojberg, A. L., Karlsson, I. B., Hinsby, K., Kidmose, J., Bessiere, H., Mansour, M., and Pulido-Velázquez, D.: Utilising data and knowledge from European geological survey organisations in climate change impact assessments and adaptations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6656, https://doi.org/10.5194/egusphere-egu2020-6656, 2020.

EGU2020-21381 | Displays | ERE1.2

The contribution of the Geological Survey of Italy to the GeoERA Programme challenges towards a geological service for Europe

Luca Guerrieri, Carlo Cipolloni, Chiara D'Ambrogi, Barbara Dessi, Pio Di Manna, Mauro Lucarini, Lucio Martarelli, and Monica Serra

The better knowledge of the subsurface is one of the challenges faced by the Geological Survey Organizations all around the world. The assessment, and sustainable use, also concurrent, of subsurface resources, requires a holistic approach that takes into account also natural hazards and environmental impacts. Such approach is particularly significant in Italy where a large part of the territory is affected by several hazards (earthquakes, landslides, floods, volcanic eruptions, ground subsidence), and the exploitation of subsurface resources has been recently a theme for a scientific and political debate to address, investigate, and manage the potential contribution  of human activities to increase natural hazards.

Exploration and knowledge, sustainable use and management, impacts, and publicly available information are key topics addressed in the GeoERA Programme by the Geological Survey of Italy (SGI) a department of ISPRA, , through the participation to eight GeoERA projects.

In the Geo-Energy Theme, the SGI contribution focuses on subsurface knowledge and database production: geological 3D model of the Po Basin subsurface as base input data for geothermal assessment of Mesozoic multilayer carbonate reservoir (HotLime); the implementation of the European Fault Database – EFD with information about faults characteristics, including 3D geometry and activity (HIKE).

As regards the Raw Materials Theme, inthe last decade, various projects aimed at implementing data and metadata on available raw materials have been fostered by the EU Commission. The projects involving SGI range from cataloguing mineral resources (MINTELL4EU) into a Database INSPIRE compliant, to the inventory of ornamental stones containing information about the physical and mechanical characteristics of the rocks (EUROLITHOS), as well as to deepen the knowledge aimed at a possible recycling/reuse of minerals from extractive wastes (FRAME) in a circular economy perspective.

In the Groundwater Theme, the main efforts of the SGI are involved on the implementation of an Italian inventory of available information on thermal-mineral water, an investigation on their geological background and the preparation of maps and web-map service (HOVER); the calculation of groundwater recharge at selected observation boreholes applying a statistical lumped model and as well using satellite data to produce spatially distributed recharge maps (TACTIC).

Finally, SGI contributes to the implementation and development of the GeoERA Information Platform that is established to support the other GeoERA projects in managing and disseminating geospatial data, reports and unstructured data, and the results of their research.

In a long term perspective, through the participation to eight GeoERA projects, the SGI has contributed to the development of a geological service for Europe built on the joint cooperation among national and regional geological surveys, that  will be the long term objective of the whole GeoERA Programme.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166.

How to cite: Guerrieri, L., Cipolloni, C., D'Ambrogi, C., Dessi, B., Di Manna, P., Lucarini, M., Martarelli, L., and Serra, M.: The contribution of the Geological Survey of Italy to the GeoERA Programme challenges towards a geological service for Europe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21381, https://doi.org/10.5194/egusphere-egu2020-21381, 2020.

EGU2020-10241 | Displays | ERE1.2

Assessing the vulnerability of shallow groundwater resources to deep subsurface energy activities (VoGERA)

Rob Ward, Koen Beerten, Willem Zaadnoordijk, Cis Slenter, Marco Bianchi, Ágnes Rotár-Szalkai, and Daniel Mallin Martin

Society is increasingly looking to the subsurface for our energy needs, be that for extracting geothermal energy, shale gas, or buffering heat, gas, or storing by-products of energy production. An increasingly crowded subsurface presents risks to groundwater relied on for water supply, since subsurface activities can introduce or release contaminants and alter subsurface properties. The VoGERA project is investigating the vulnerability of shallow groundwater from a range of subsurface energy technologies across different hydrogeological and geological settings within Europe. A suite of conceptual models compares the intrinsic vulnerability for different geological (crystalline, poorly consolidated and well consolidated sedimentary basins) and hydrogeological (basin centre and margins) conditions. They also consider the impacts of different subsurface activity types broadly categorised as those processes including injection, abstraction and a neutral fluid balance. Potential contamination pathways are being investigated at four case study sites; the Rauw Fault in Belgium, Panonian Basin in Hungary, The Peel Boundary Fault in the Netherlands and the Vale of Pickering in the UK. Geophysical, hydrological and hydrochemical data from these sites will be assessed in order to improve contamination pathway process understanding in a European setting. Findings from the case study sites will be used to evaluate the conceptual models and to develop a tool for decision makers and the public to assess the vulnerability to shallow groundwater from subsurface energy activities depending on the activity, and geological and hydrogeological conditions at a specific location. The VoGERA project is funded as part of the European Union’s Horizon 2020 GeoERA network of projects under the Groundwater theme (Grant agreement number 731166).

How to cite: Ward, R., Beerten, K., Zaadnoordijk, W., Slenter, C., Bianchi, M., Rotár-Szalkai, Á., and Mallin Martin, D.: Assessing the vulnerability of shallow groundwater resources to deep subsurface energy activities (VoGERA), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10241, https://doi.org/10.5194/egusphere-egu2020-10241, 2020.

EGU2020-14037 | Displays | ERE1.2

GeoEra HOVER WP7 – Harmonized vulnerability to pollution mapping of the upper aquifer

Andreas Günther, Stefan Broda, Klaus Duscher, Jörg Reichling, Susanne Schomburgk, Daniel Elster, Boris Bimalyuk, Sonja Cerar, Birgitte Hansen, Caoimhe Hickey, Juuso Ikonen, Ignasi Herms, Kostas Kontodimos, David Pulido Velázquez, Diana Persa, Silvio Janetz, Melanie Witthoeft, Jurga Arustiene, Nora Gal, and Magdalena Nidental and the GEOERA HOVER WP7 TEAM

45 Geological Survey Organisations (GSOs) from 32 European countries developed an ERA-NET Co-Fund Action: Establishing the European Geological Surveys Research Area to deliver a Geological Service for Europe (GeoERA). The GeoEra project HOVER (Hydrogeological processes and Geological settings over Europe controlling dissolved geogenic and anthropogenic elements in groundwater of relevance to human health and the status of dependent ecosystems) aims to gain understanding of the controls on groundwater quality across Europe using the combined expertise and data held by member states. Objectives of the HOVER work package 7 (WP7) are i) review of existing index methods for assessing the vulnerability of the upper aquifer to pollution and selection of the methods to be applied at the pilot and pan-EU scale, ii) compilation and harmonization of input data sets required for assessing vulnerability, and iii) assessment of aquifer vulnerability to pollution (both in maps and 2-d schematic cross sections).

The selected methodology adopted in this project is DRASTIC, which will be applied in ten pilot areas and at the pan-European scale. In karst regions, however, the COP method will be applied in the pilots. This is accompanied with comparisons with the outcomes of existing national vulnerability assessments. It is anticipated to validate the resulting vulnerability maps at the pilot level using available groundwater nitrate contamination information.

How to cite: Günther, A., Broda, S., Duscher, K., Reichling, J., Schomburgk, S., Elster, D., Bimalyuk, B., Cerar, S., Hansen, B., Hickey, C., Ikonen, J., Herms, I., Kontodimos, K., Velázquez, D. P., Persa, D., Janetz, S., Witthoeft, M., Arustiene, J., Gal, N., and Nidental, M. and the GEOERA HOVER WP7 TEAM: GeoEra HOVER WP7 – Harmonized vulnerability to pollution mapping of the upper aquifer, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14037, https://doi.org/10.5194/egusphere-egu2020-14037, 2020.

EGU2020-4861 | Displays | ERE1.2

A pan-European GIS focused on gas hydrates: a research base-line in geohazards and geological storage of CO2

Ricardo Leon, Christopher Rochelle, André Burnol, Carmen Julia Gimenez-Moreno, Tove Nielsen, John Hopper, Isabel Reguera, Pilar Mata, Margaret Stewart, and Silvia Cervel

Abstract

A pan-European GIS focused on hydrate has been developed within the frame of the GARAH project (GeoERA - GeoE.171.002) in order to assess gas hydrate information gaps in the European margins. A data-collection exercise from public sources (MIGRATE and PERGAMON COST actions ES1405 and ES0902, SeaDataNet, NOAA, etc) and European Geological Surveys (BGS, BRGM, IGME, GEUS, etc) has supplied a total of 835 information layers. All this information has been structured in four groups ((i) Geological & Geochemical evidences/indicators, (ii) Geophysical indicators, (iii) Fluid flow seabed indicators and (iv) Oceanographic variables & Geological constrains) where tables and geospatial features have been designed and harmonized following the standards of INSPIRE directives.

This GIS-database has been conceived as a first step or base-line for future gas hydrate related research. The next step as part of 'Work Package 3' of the GARAH project will be the identification of critical knowledge gaps and the definition of specific areas of interest which would benefit from further research. Theses potential future projects could be related to improving the European model of the gas hydrate stability zone (GHSZ), assess potential geohazards and risks, assess the abundance of sediment-hosted gas hydrates, and evaluate the role of CO2-rich hydrates for the geological storage of CO2.

 

Acknowledgment

GARAH project. GeoERA - GeoE.171.002

 

How to cite: Leon, R., Rochelle, C., Burnol, A., Gimenez-Moreno, C. J., Nielsen, T., Hopper, J., Reguera, I., Mata, P., Stewart, M., and Cervel, S.: A pan-European GIS focused on gas hydrates: a research base-line in geohazards and geological storage of CO2, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4861, https://doi.org/10.5194/egusphere-egu2020-4861, 2020.

EGU2020-1558 | Displays | ERE1.2

Unconventional hydrocarbon resource plays in the North Sea Basin, Northwestern Europe

Niels Schovsbo, Stefan Ladage, Anders Mathiesen, Susanne Nelskamp, Margaret A. Stewart, and Peter Britze

In 2017 the geological surveys contributed to the European wide project ‘EU Unconventional Oil and Gas Assessment’ (EUOGA). The goal of EUOGA was to assess all potentially prospective shale formations from the main onshore basins in Europe and included contributions of twenty-one European geological surveys and the assessment covered 82 geological formations from 38 basins (Zijp et al. 2017).

To extend the assessment to offshore basins the geological surveys of Denmark (GEUS), Germany (BGR), the Northlands (TNO) and United Kingdom (BGS) are working together on the Geological Analysis and Resource Assessment of selected Hydrocarbon systems (GARAH) project that aims at assessing the conventional and unconventional hydrocarbon resource in the North Sea Basin. Within the basin more than 10 shale layers have been recognised as holding potential resources. These shales include the offshore equivalent of the Cambrian Alum Shale, The Carboniferous Bowland shale and the Jurassic Wealden and Kimmeridge shales that onshore have been a target for hydrocarbon exploration within the European Union member states. Each shale layer will be characterized using thirty systematic parameters such as areal distribution, structural setting, average net to gross ratio of the shale reservoir, average Total Organic Carbon content (TOC) and average mineralogical composition.

This is a part of an ongoing EU Horizon 2020 GeoERA project (The GARAH, H2020 grant #731166 lead by GEUS).

References

Zijp, M., Nelskamp, S., Schovsbo, N.H., Tougaard, L. & Bocin-Dumitriu, A. 2017: Resource estimation of eighty-two European shale formations. Proceedings of the 5th Unconventional Resources Technology Conference, Austin, Texas, USA, 24–26 July, 2017. https://doi.org/10.15530/urtec-2017-2686270

How to cite: Schovsbo, N., Ladage, S., Mathiesen, A., Nelskamp, S., Stewart, M. A., and Britze, P.: Unconventional hydrocarbon resource plays in the North Sea Basin, Northwestern Europe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1558, https://doi.org/10.5194/egusphere-egu2020-1558, 2020.

EGU2020-20918 | Displays | ERE1.2

Overview of conventional hydrocarbon resources in the North Sea Basin – harmonization of assessments, cross-border play mapping and new concepts

Susanne Nelskamp, Margaret Steward, Niels Schovsbo, Stefan Ladage, Stefan Peeters, and Peter Britze

A cross-border assessment study looking at selected hydrocarbon systems is conducted as part of the EU Horizon 2020 GeoERA project (GARAH H2020 grant #731166 lead by GEUS). Within this project the geological surveys of the Netherlands (TNO), Germany (BGR), the United Kingdom (BGS) and Denmark (GEUS) are working together to create an overview of hydrocarbon resources and potential plays in the North Sea Basin. The project will harmonize the available resource assessments, and take a closer look at the play systems and potential new concepts. The focus of the work is on resolving border issues and identifying play concepts that are successful in one country but are underexplored in others. Potential risk factors related to subsurface exploration and production as well as options for multiple use of the subsurface will also be included in the overview. The results of the project will be published in report and GIS format and made available to legislators as well as the public.

Other parts of the project include the assessment of unconventional hydrocarbon plays (see Schovsbo et al. this conference), detailed basin and petroleum system modelling of a case study area in the Danish-German-Dutch offshore area (Lutz et al. this conference) and a pan-European database for gas hydrates (Léon et al. this conference).

How to cite: Nelskamp, S., Steward, M., Schovsbo, N., Ladage, S., Peeters, S., and Britze, P.: Overview of conventional hydrocarbon resources in the North Sea Basin – harmonization of assessments, cross-border play mapping and new concepts, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20918, https://doi.org/10.5194/egusphere-egu2020-20918, 2020.

EGU2020-6873 | Displays | ERE1.2

3D basin and petroleum system modelling in the North Sea Central Graben - a Dutch, German, Danish cross-border study

Rüdiger Lutz, Jashar Arfai, Susanne Nelskamp, Anders Mathiesen, Niels Hemmingsen Schovsbo, Stefan Ladage, Peter Britze, and Margaret Stewart

A Geological Analysis and Resource Assessment of selected Hydrocarbon Systems (GARAH) is carried out as part of the overarching GeoERA project. Here, we report first results of a 3D basin and petroleum system model developed in a cross-border area of the Dutch, Danish and German North Sea Central Graben area. This pilot study reconstructs the thermal history, maturity and petroleum generation of potential Lower, Middle and Upper Jurassic source rocks. The 3D pilot study incorporates new aggregated and combined layers from the three countries. Results of the study feed back into the 3DGEO-EU project of GeoERA.

Eight key horizons covering the whole German Central Graben and parts of the Dutch and Danish North Sea Central Graben were selected for building the stratigraphic and geological framework of the 3D basin and petroleum system model. The model includes depth and thickness maps of important stratigraphic units as well as the main salt structures. Petrophysical parameters, generalized facies information and organic geochemical data from well reports are assigned to the different key geological layers. The model is further calibrated with temperature and maturity data from wells of the three countries and from publications. The time span from the Late Permian to the Present is represented by the model including the most important erosional phases related to large-scale tectonic events during the Late Jurassic to Late Cretaceous. Additionally, salt movement through time expressed as diapirs and pillows is considered within the 3D basin and petroleum system model.

This is a part of an ongoing EU Horizon 2020 GeoERA project (The GARAH, H2020 grant #731166 lead by GEUS).

How to cite: Lutz, R., Arfai, J., Nelskamp, S., Mathiesen, A., Schovsbo, N. H., Ladage, S., Britze, P., and Stewart, M.: 3D basin and petroleum system modelling in the North Sea Central Graben - a Dutch, German, Danish cross-border study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6873, https://doi.org/10.5194/egusphere-egu2020-6873, 2020.

EGU2020-15823 | Displays | ERE1.2

Investigating geological processes and their links with geological structures through geomanifestations

Renata Barros, Kris Piessens, Helga Ferket, Nina Rman, and Éva Kun

GeoConnect³d introduced the concept of geomanifestations to define any distinct local expression of ongoing or past geological processes. These manifestations, or anomalies, often point to specific geologic conditions and, therefore, can be important sources of information to improve geological understanding of an area. Examples include seismicity, gas seeps, local compositional differences in groundwater and springs, thermal anomalies, mineral occurrences, jumps in hydraulic head, overpressured zones and geomorphological features. Geomanifestations are an addition to the structural framework model also being developed in GeoConnect³d, aiming to show where and how processes and structures may be linked.

Data on geomanifestations are being collected in three areas: the Roer-to-Rhine area of interest in northwest Europe, and the Mura-Zala Basin and Battonya High within the Pannonian Basin area of interest in Eastern Europe. A first assessment of available data showed that groundwater-related geomanifestations in the form of anomalies in chemical composition (enrichment in elements such as Fe, or hydrocarbon gases and CO2,) or temperature (thermal water springs, geothermal anomaly in wells) are mappable in all areas. These geomanifestations point to special geological features in each area, such as proximity to magmatic reservoirs, presence of deep-rooted faults and considerable differences in the subsurface relief (trough–high system of the basement) among others. These anomalies at times define spatial patterns, which might or not be represented in the structural framework model, thus demonstrating whether they can be explained by the current geological understanding embedded in the structural framework. With this first test, we conclude that data on groundwater-related geomanifestations add to the robustness of the structural framework model. Further investigations with other types of geomanifestations are foreseen.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166.

How to cite: Barros, R., Piessens, K., Ferket, H., Rman, N., and Kun, É.: Investigating geological processes and their links with geological structures through geomanifestations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15823, https://doi.org/10.5194/egusphere-egu2020-15823, 2020.

EGU2020-9579 | Displays | ERE1.2

The BSI indicator: preventing thermal interferences between groundwater heat pump systems

Alejandro García-Gil, Miguel Ángel Marazuela, Miguel Mejías Moreno, Enric Vázquez-Suñè, Eduardo Garrido Schneider, and José Ángel Sánchez-Navarro

Shallow geothermal systems are the most efficient and clean technology for the air-conditioning of buildings and constitutes an emergent renewable energy resource in the worldwide market. Undisturbed systems are capable of efficiently exchanging heat with the subsurface and transferring it to human infrastructures, providing the basis for the successful decarbonisation of heating and cooling demands of cities. Unmanaged intensive use of groundwater for thermal purposes as a shallow geothermal energy (SGE) resource in urban environments threatens the resources´ renewability and the systems´ performance, due to the thermal interferences created by a biased energy demand throughout the year. To ensure sustainability, scientifically-based criteria are required to prevent potential thermal interferences between geothermal systems. In this work, a management indicator (balanced sustainability index, BSI) applicable to groundwater heat pump systems is defined to assign a quantitative value of sustainability to each system, based on their intrinsic potential to produce thermal interference. The BSI indicator relies on the net heat balance transferred to the terrain throughout the year and the maximum seasonal thermal load associated. To define this indicator, 75 heating-cooling scenarios based in 23 real systems were established to cover all possible different operational conditions. The scenarios were simulated in a standard numerical model, adopted as a reference framework, and thermal impacts were evaluated. Two polynomial regression models were used for the interpolation of thermal impacts, thus allowing the direct calculation of the sustainability indicator developed as a function of heating-cooling ratios and maximum seasonal thermal loads. The BSI indicator could provide authorities and technicians with scientifically-based criteria to establish geothermal monitoring programs, which are critical to maintain the implementation rates and renewability of these systems in the cities.

How to cite: García-Gil, A., Marazuela, M. Á., Mejías Moreno, M., Vázquez-Suñè, E., Garrido Schneider, E., and Sánchez-Navarro, J. Á.: The BSI indicator: preventing thermal interferences between groundwater heat pump systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9579, https://doi.org/10.5194/egusphere-egu2020-9579, 2020.

EGU2020-7947 | Displays | ERE1.2

Mineral resources - crucial components of a vital and wealthy society

Antje Wittenberg, Daniel P. S. de Oliveira, Javier González Sanz, Lisbeth Flindt Jørgensen, David Whitehead, and Tom Heldal

Changes in our world mean that Europe is facing many pressing demographic and geographic challenges. A growing, aging population coupled with changes in population density are causing environmental stresses to our ecosystem that when coupled with climate change create challenges in sustainable food production and the use of natural raw materials. At the same time, the Fridays For Future Movement is calling out loudly for Future and Climate Justice, CO2-neutrality, resource efficiency and (almost) closed material loops. These issues are already expressed by the 17 UN sustainable development goals (SDGs) and widely shared through the Paris Agreement. The European Union and the National Governments have launched many frameworks and action plans such as the European Green Deal to achieve a carbon-neutral economy and clean mobility for example. Certainly, any of those transformations and any infrastructure developments will require sustainably produced mineral raw materials to deliver key enabling technologies and to meet the needs of the Industry 4.0 society. Moreover, improvements in buildings such as energy efficiency through insulation technologies, other infrastructure developments and the Europe’s cultural heritage preservation add to the increasing demand in mineral resources.

The demand for ever increasing volumes of mineral resources cannot be met exclusively by recycling and thermodynamics does not allow for fully closed material loops. Hence, a sustainable supply of raw materials will always require accessibility to mineral deposits and productive mines while the effects of competing land-use issues and NIMBY activism are increasing too.

The realisation of a low-carbon society and a self-concept of reliable sourcing increasingly require short feed strokes and local sourcing. A good understanding of mineral systems, mining sites, and remaining resources of historical sites will stay of utmost importance. The four GeoERA Raw Materials projects* EuroLITHOS, FRAME, MINDeSEA and Mintell4EU share expertise, information and focus on European on-shore and off-shore resources.

EuroLITHOS gives specific attention to ornamental stone resources for which Europe has a long tradition in mining, processing and usage.

FRAME designed to research the Strategic and Critical Raw Materials (SCRM) in Europe to gain new insights into reserves and resources taking into account new technologies and developments.

MINDeSEA focuses on exploration and investigation of SCRM from seafloor mineral deposits in European waters. Identifying areas for responsible resourcing and information on management and Marine Spatial Planning in European Seas are in its core of action.

Mintell4EU focuses on harmonizing data, utilizes the UNFC, providing spatial data and thematic maps. Updated electronic Minerals Yearbook and Europe’s Minerals Inventory are among the products.

Foresight and forecasting of the raw material supply potential of Europe will become more reliable through increased data quality and harmonization. Workshops and training courses will add to ensure an improvement of the European Raw Materials Knowledge Base. GeoERA Raw Materials projects create valuable, accessible and public data, and information for policy-makers and end-users of geological data and minerals information in Europe.

 

[*] This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166

How to cite: Wittenberg, A., de Oliveira, D. P. S., González Sanz, J., Flindt Jørgensen, L., Whitehead, D., and Heldal, T.: Mineral resources - crucial components of a vital and wealthy society, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7947, https://doi.org/10.5194/egusphere-egu2020-7947, 2020.

EGU2020-7025 | Displays | ERE1.2

Lithium, Cobalt and Graphite occurrences in Europe, Results from GeoEra FRAME project wp 5

Håvard Gautneb, Eric Gloaguen, and Tuomo Törmänen

The H2020 GeoERAFRAME project (www.frame.lneg.pt) consists of a partnership of 11 European geological surveys. Geographical and geological information was collected including the genetic type of the different commodities. In the EU, data show that there are 1195 registered occurrences, prospects or deposits of Li, Co and graphite, of these only 17 are active. The data classify the occurrences according to their genetic type, occurrence type and production status. The data have been supplied from geological surveys national databases and in this compilation, we regard all Co deposits with a mean Co >100ppm as potential occurrences for Co. For the other commodities, Li bearing minerals or graphite must be identified or explored for to be included.
Even if our compilation has shown that the different national resource databases contain data of variable quality, with a lot of shortcomings, inconsistences and errors, the overall quality is good enough to assess the EU potential.

The Lithium deposits can be group into the following types: i) High grade Li deposits including Li-rich LCT pegmatites, rare metal granites and atypical stratiform deposits such as Jadar. The distribution of lithium in Europe shows a strong clustering highlighting the Li potential of the Variscan belt of south and central Europe. Representative examples are Sepeda pegmatites (103 000t Li2O – grade 1.0%) or Beauvoir rare-metal granite (325 260t Li2O – grade 0.78%). Medium-grade Li deposits are represented by hydrothermal deposits such as greisens and Li-bearing quartz veins associated to some peraluminous rare metal granites (Cinovec 2 715 010 Li2O – grade 0.42%).

Cobalt is a common minor constituent in a number of different ore types. In Europe, most of the known Co-bearing deposits and showings are clustering in the Nordic countries (Finland, Sweden and Norway). In the Nordic countries, the deposits mostly represent magmatic Ni-Cu and Fe-Ti-V deposits and VMS deposits, whereas elsewhere in Europe genetic types are more varied from sediment-hosted, to lateritic and 5-element vein types, among others. The only active mines producing cobalt are located in Finland. Kevitsa mine in northern Finland is a large low-grade Ni-Cu-PGE deposit, which produced 591 t of Co in 2018. Kylylahti mine is a small-sized Outokumpu-type Cu-Zn-Ni-Co deposit, which produced 278 t of Co in 2018. Terrafame is a large, low-grade black-shale hosted Zn-Ni-Cu-Co mine that produces Co as by product to Ni and Zn.

Graphite is a common mineral in rocks throughout Europe. However, find economically interesting deposits are rare. The bulk of the graphite occurrences occur in Archean or Proterozoic rocks of Fennoscandia and Ukraine. In addition, a number of amorphous graphite occurrences are found in Phanerozoic rocks in Austria. There are also a large number of showings where the genetic type is unknown. Active mines are situated in Ukraine, Austria and Norway. The graphite bearing rocks are typically organic rich para-gneiss often associated with carbonates and iron formations. The graphite content varies from 2-3% up to over 40%. The Trælen deposit in Norway is the world’s richest graphite deposit in current production with an average ore grade of 31%.

How to cite: Gautneb, H., Gloaguen, E., and Törmänen, T.: Lithium, Cobalt and Graphite occurrences in Europe, Results from GeoEra FRAME project wp 5, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7025, https://doi.org/10.5194/egusphere-egu2020-7025, 2020.

EGU2020-7931 | Displays | ERE1.2

Prospectivity mapping of niobium and tantalum in Europe; a part of the GEOERA- FRAME project

Martiya Sadeghi, Guillaume Bertrand, Helge Reginiussen, Nikolas Arvanitidis, Erik Jonsson, and Daniel P.S. de Oliveira

The prime aim of work package (WP) 3 in the FRAME project is to produce a map of Strategic and Critical Raw Materials (SCRM) for Europe, including the so-called energy and conflict minerals. In cooperation with other FRAME WPs, there was a consensus on the methodology used for the identification and selection process of the Strategic and Critical Raw Materials (SCRM) to be included in the metallogenetic map, linked mainly to information collected from existing databases (DB), such as Minerals4EU (M4EU) and European Geological Data Infrastructure (EGDI). 

One main objective of WP3 is the predictive targeting based on GIS exploration tools and prospectivity assessments at continental scale. Two types of prospectivity mapping have been produced in this WP3 based on different knowledge and data-driven methods. The first method applies the latest developments in “data driven” mineral prospectivity that allows mapping at continental scale, such as the “Cell Based Association" (CBA) one method developed by BRGM. CBA is an alternative to GIS-supported prospectivity methods. It has been developed to better manage uncertainties related to cartographic data which are highly significant at continental scale. The second method is using the hybrid fuzzy weights-of-evidence (WofE) model for mineral potential mapping.

SCRM may be recovered either as primary commodities or as by-products. Carbonatite-related deposits are the primary sources of many CRM such as REEs, niobium (Nb) and tantalum (Ta). Granitic pegmatite deposits are currently the principal source of Ta. Compilation of Nb and Ta occurrences/deposits in Europe is currently going on within FRAME WP6 (see separate presentation by Reginiussen et al., this conference). The data has been used for the spatial analysis and prospectivity mapping related to geology and geotectonic and metallogenic setting at European scale.

The results of our prospectivity mapping highlight several Nb and Ta mineral potential areas related to evolved granite to leucogranite bodies mostly in Scandinavia, Spain, France and Portugal, e.g Morille-Martinamor district, Fontão and Penouta where previous exploration activities on those elements were carried out in past. The late Neoproterozoic to early Cambrian Schist-Greywacke Complex (SGC) of the Variscan belt, in Central Iberian Zone, is also indicated as favourable area for Nb and Ta. Pegmatites in the Campo Mineiro De Lagares in the CIZ are another area of interest. Pegmatites in central Iberian zone is another area of interest, as is the case for Campo Mineiro De Lagares. The late Neoproterozoic to early Cambrian Schist-Greywacke Complex (SGC) of the Variscan belt, in Central Iberian Zone, is also indicated as favourable area for Nb and Ta. . In Sweden, the pegmatites of the Varuträskt area, close to Skellefteå, dated to c. 1.8-1.77 Ga, are clearly highlighted in the prospectivity maps. The areas related to Fennoscandian carbonatites appear also to be strongly favourable as Nb and Ta mineral potential targets. In the northern, central and southern parts of Sweden, high to moderately favourable areas are related to the numerous individual and granitic pegmatite dykes of Proterozoic age.

How to cite: Sadeghi, M., Bertrand, G., Reginiussen, H., Arvanitidis, N., Jonsson, E., and de Oliveira, D. P. S.: Prospectivity mapping of niobium and tantalum in Europe; a part of the GEOERA- FRAME project , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7931, https://doi.org/10.5194/egusphere-egu2020-7931, 2020.

EGU2020-10228 | Displays | ERE1.2

FRAME: towards conflict-free Nb-Ta for the European Union

Helge Reginiussen, Erik Jonsson, Susana María Timón Sánchez, Alejandro Díez Montes, Klemen Teran, Rute Salgueiro, Augusto Filipe, Carlos Inverno, and Daniel P.S. de Oliveira

The GeoERA FRAME project focuses on several of the main raw material-related objectives of the EU Commission. FRAME work package 6 (WP6), targets so-called conflict minerals, chiefly those mined to extract niobium (Nb) and tantalum (Ta).  These chemically related critical metals are essential components in a range of applications and products including electronics, steel alloys and superalloys widely required by the European industry. Today, significant amounts of Ta and associated Nb are sourced as conflict minerals from the central African region, not least the DRC (Congo-Kinshasa).

A main objective of FRAME WP6 is to do a survey of the European distribution of these metals and their deposits, thus enhancing their exploration interest and potential to help enable ethical and indigenous production for the EU.

While WP6 compiles data on Nb-Ta mineralisations from the whole of Europe, the main focus is put on the Swedish part of the Fennoscandian Shield and the Iberian Variscan Massif.

The Nb-Ta mineralisations of the Iberian Peninsula belong to the southwestern extension of the European Variscan Belt. From both an economic and a metallogenetic point of view, the most interesting Nb-Ta deposits in Spain are those in which mineralisation occurs as disseminations throughout small leucogranite bodies, as is the case for the deposits Golpejas, El Trasquilón, Fontao, Penouta and in some occurrences of the Morille-Martinamor district. These have been exploited previously for Sn, Ta-Nb, and/or W. Penouta, which is the biggest known Ta-deposit in Spain, was mined intermittently between 1906-1985. The mine has recently started re-processing old tailings. Most Nb-Ta mineralisations in the Fennoscandian Shield are hosted by LCT-type (lithium-cesium-tantalum-enriched) granitic pegmatites that occur mainly in regions featuring abundant Palaeoproterozoic low to low- medium-grade metasedimentary rocks and associated S-type granites. Some of these have been studied during different earlier exploration campaigns. NYF-type (niobium-yttrium-fluorine-enriched) granitic pegmatites occur as individual dykes and fields throughout the Proterozoic bedrock of Sweden. Research in WP6 will focus on a few selected Swedish deposits and occurrences including Järkvissle and Bergby in central Sweden, as well as Stripåsen, Utö and other rare-element pegmatites in the Bergslagen province. Emphasis during the start of the project was to identify key areas and mineralisations within these two regions that can be studied in detail.

Based on available information in the databases and archives of the partner surveys, a list of Nb-Ta occurrences and deposits has been produced. Ultimately, at the end of the project, a report on the distribution and systematics of Nb-Ta mineralisations in Europe will also be produced. Prospective regions and their character of mineralisation will be summarized together with the overall European potential, in order to develop recommendations for future exploration. Furthermore, a discussion of conditions of Nb-Ta production in central Africa with the aim to suggest improvement to these issues will be made. The potential of intra-European production of Nb-Ta to decrease the present near-total dependence on imports will also be assessed. As another outcome, an Inspire-compatible pan-European dataset of Nb-Ta mineralisations will be provided to the GeoERA information platform.

How to cite: Reginiussen, H., Jonsson, E., Timón Sánchez, S. M., Díez Montes, A., Teran, K., Salgueiro, R., Filipe, A., Inverno, C., and de Oliveira, D. P. S.: FRAME: towards conflict-free Nb-Ta for the European Union , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10228, https://doi.org/10.5194/egusphere-egu2020-10228, 2020.

EGU2020-16935 | Displays | ERE1.2

Mintell4EU – Mineral Intelligence for Europe – a GeoERA project to improve and sustain the European raw materials knowledge base.

David Whitehead, Lisbeth Flindt Jørgensen, Mikael Pedersen, Teresa Brown, Špela Kumelj, Kari Aslaksen Aasly, and Ulrich Clain

There is a need for comprehensive, up-to-date, reliable and harmonised cross-border information on raw materials to improve resource efficiency across Europe. The Mintell4EU project builds on the achievements of previous projects such as Minerals4EU, ProSUM and Minventory to deliver data on the spatial distribution, production, trade, resource potential and levels of exploration activity to support decision making in government and industry.

The project has four principle components. The first component involves updating production, trade and exploration statistical data within the electronic European minerals yearbook. The second component includes extending the spatial coverage and improvement of spatial data quality within the Minerals4EU database. The third component will demonstrate how the application of the United Nations Framework Classification (UNFC) will provide a tool that can be used to more accurately assess European mineral inventories. The final component involves consolidating the electronic European minerals yearbook into the Minerals4EU database used for external systems such as the European Geological Data Infrastructure (EGDI) and the Joint Research Center’s Raw Materials Information System (RMIS). Another important goal of the project is to create a sustainable platform for raw materials.

The project works in collaboration with other GeoERA projects within the theme of raw materials such as FRAME and the GeoERA Information Platform Project (GIP-P). This collaboration is critical in ensuring data harmonisation across projects, regions and focus areas. Improvements in the quality and availability of data that are available through the web portal on the project home page https://geoera.eu/projects/mintell4eu7/ have already been achieved. Work will continue on improving the availability and relevance of raw material data throughout the remainder of the project. This will lead to improved foresight of the raw material supply situation and potential of Europe within the framework of the United Nations Sustainable Development Goals (SDGs).

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166

How to cite: Whitehead, D., Flindt Jørgensen, L., Pedersen, M., Brown, T., Kumelj, Š., Aslaksen Aasly, K., and Clain, U.: Mintell4EU – Mineral Intelligence for Europe – a GeoERA project to improve and sustain the European raw materials knowledge base., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16935, https://doi.org/10.5194/egusphere-egu2020-16935, 2020.

EGU2020-20781 | Displays | ERE1.2

Atlas of European ornamental stone resources

Tom Heldal, Jorge Carvalho, Željko Dedić, and Kostas Laskarides

Ornamental stone is today a raw material produced with great skills all over Europe, SME's and larger enterprises exploiting the vast diversity of European ornamental stone resources. Today's European stone industry is not only large and important but also highly dispersed throughout Europe, making a backbone industry for particularly rural areas. In Italy alone, there are more than 1000 stone quarrying enterprises and the sector in total employed more than 50 000 in 2011. Ornamental stone has contributed significantly in shaping our rural and urban landscapes, through its use in our built heritage from different historical periods. Yet, the actual use of local and regional stone resources in Europe is under threat due to sterilization of resources by urbanisation, infrastructure development and other land uses. Consequently, important resources are “unknowingly” lost for future production, and so are vital geological knowledge and skills for producing them. Loss of such resources will not only make it more difficult to maintain and restore our architectural heritage, but also prevent the use of traditional materials in the future.

The motivation behind the EuroLithos project, as a part of the GeoERA partnership, was to reverse this gradual process of loss, by providing a European scale knowledge base for ornamental stone resources; their spatial occurrence and distribution, their technical properties and quality, as well as providing guidelines for how to assess economic and non-economic values.

A major challenge in the project is to collect data from many national repositories and display them in a harmonised way. The spatial extent of ornamental stone resources can basically be measured by the spatial distribution of the geological units containing the valuable quarries and future resources of same quality. Another challenge is how to link geological units with ornamental stone commodities of the INSPIRE standard, and a third is how to collect and display technical information about ornamental stone and how to link that to the spatial data. So far, EuroLithos has provided agreement among 15 partners in 14 countries on how to meet these challenges, and guidelines on how to deliver data according to this agreement. Ongoing, 12 case studies across Europe covering different aspects of resource valorisation are currently running. Eurolithos will be running until July 2021, and more results can be viewed at www.eurolithos.org.

How to cite: Heldal, T., Carvalho, J., Dedić, Ž., and Laskarides, K.: Atlas of European ornamental stone resources, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20781, https://doi.org/10.5194/egusphere-egu2020-20781, 2020.

EGU2020-22091 | Displays | ERE1.2

Hydrogenetic Fe-Mn crusts from European seas: source of potentially economic cobalt mining.

Egidio Marino, Javier González, Teresa Medialdea, Luis Somoza, Rosario Lunar, Pedro Ferreira, Thomas Kuhn, James R. Hein, Vitor Magalhaes, and Iker Blasco

The world increasing demand of electric vehicles (EVs) that use lithium-ion batteries (LIB), in which cobalt is one of the essential elements, focused the attention on its demand that is calculated will increase of 7-13% annually until 2030. The actual production of cobalt, usually extract as by-product of nickel and copper mine, is reduced to almost 20 countries between which the Democratic Republic of the Congo is the bigger producer with 55% of the world production. In Europe cobalt is produced only in Finland that actually provides 2.300 tonnes, the 2% of the world production. In this way several projects have been promoted by European Union, with the Raw Material Initiative, in order to find and evaluate the sustainable production of important materials in Europe.

MINDeSEA[1] project is part of the GeoERA and represent the collaboration of 12 national geological institution partners, to characterize marine deposits and their contents in Critical Raw Materials (CRM) and to generate a comprehensive cartography and metallogenic models of them. The first preliminary map produced in 2019 represents the localization and evaluation of cobalt rich deposits in the oceans within the EEZ and ECS of the European countries.  Cobalt deposits are represented essentially by hydrogenetic Fe-Mn crusts located essentially in the Macaronesian area of the north east Atlantic Ocean (in the Portugal and Spain), submarine plateaus, as the Galicia Bank (in the north west Spanish) and in the Arctic Ocean ridges (Norway and Iceland). The report differentiates between occurrences (<0.05 wt. %) and deposits (>0.05 wt. %), with the possibility of more than 200 Mt resources per potential deposit.

Detailed mineralogical, geochemical and metallogenic studies are being developed in crusts from the Macaronesia. Fe-Mn crusts absorb dissolved elements in seawaters on the surface of the fresh precipitated oxy-hydroxides during their slow growth through millions of years. Several elements are concentrated in Fe-Mn crusts and between them cobalt is one of the most enriched trace metals (average 0.6 wt. %) accompanied by other strategic and critical metals such as nickel, copper, tellurium, molybdenum and rare earth elements plus yttrium (REY) (respectively 3000, 500, 150, 500 and 3500 µg/g). Micro Raman and micro X-Ray diffraction can be used to differentiate the mineralogy in laminae of less than 20 microns. On the other hand, electron probe micro-analyzer (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), are useful in order to quantify contents of CRM in the different mineral phases. These are innovative techniques in order to identify critical-elements bearing minerals and thus choose the metallurgic method for a more efficient and sustainable extraction of the interesting elements.

The evaluation of a seamount as a future mine site has to take into account all these mineralogical and chemical features as well as a proper knowledge of the seamount (morpho-structure, geology, oceanography, ecosystems) and the Fe-Mn crust thickness and extension


[1] This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 731166

How to cite: Marino, E., González, J., Medialdea, T., Somoza, L., Lunar, R., Ferreira, P., Kuhn, T., Hein, J. R., Magalhaes, V., and Blasco, I.: Hydrogenetic Fe-Mn crusts from European seas: source of potentially economic cobalt mining., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22091, https://doi.org/10.5194/egusphere-egu2020-22091, 2020.

ERE1.4 – The Environment and Smart Circular Economy and Cities: A New Geo management Approach

EGU2020-12854 | Displays | ERE1.4

Potential of nature-based solutions for creating resourceful circular cities

Günter Langergraber and Natasa Atanasova

The COST Action Circular City (CA17133; "Implementing nature-based solutions for creating a resourceful circular city") aims to establish a network testing the hypothesis that a circular flow system that implements nature-based solutions (NBS) for managing nutrients and resources within the urban biosphere will lead to a resilient, sustainable and healthy urban environment. To date, most NBS are implemented serving only one single purpose. Adopting the concept of circular economy by combining different types of services and returning resources to the city, would increase the benefits gained for urban areas.

The Action's main output will be a guideline on combined NBS and circular economy possibilities within the urban environment. The work to achieve this will be carried out in five working groups (WGs):

  • WG1 "Built environment" investigates the NBS - circular economy aspect on building and settlement level with the main focus on vegetated building materials and resources to be obtained from the corresponding NBS.
  • WG2 "Sustainable urban water utilization" considers the implementation of a save and functional water cycle within the urban biosphere, defines available resources within the water flow, performs risk assessment on urban water and evaluates NBS for storm water management and waste water treatment.
  • WG3 "Resource recovery" aims to transform implemented NBS for mitigation or treatment purposes to sources for a variety of resources to be harvested, used, reused and recycled.
  • WG4 "Urban Farming" facilitates the implementation of urban farming with main purpose of food production within a city, but additionally paying close attention to other resources available from urban farming, usually considered waste.
  • Last but not least, WG5 "Transformation tools" coordinates and leads the interdisciplinary activities between the WGs with the main aim to facilitate implementation of NBS in circular cities by 1) investigate performance-based assessment tools, 2) developing simplified tools and information for stakeholders, and 3) establish public relations strategies and approaches.

The contribution will present the results already achieved by the WGs by summarizing main results from the review papers each WG has produced.

How to cite: Langergraber, G. and Atanasova, N.: Potential of nature-based solutions for creating resourceful circular cities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12854, https://doi.org/10.5194/egusphere-egu2020-12854, 2020.

EGU2020-9171 | Displays | ERE1.4 | Highlight

A missing link - site resource inventories for the circular city

Gösta Baganz, Daniela Baganz, Georg Staaks, and Werner Kloas

The concept of the circular city (CC) can be employed to mitigate the impact of the Food-Water-Energy Nexus on the environment at the local as well as the global level. The CC is based on circular economy (CE) ideas, where one of the key elements is coupling: unused and/or waste output of CE-entities can be used as input to other CE-entities. Due to the nature of some CE-entities, they need to be located in the proximity of other suitable CE-entities within the build environment.

Policies and strategies on the level of the EU, city, or district deliver an orientation; zoning law and building codes sets the legal frame when integrating a CE undertaking into the urban fabric. Based on the requirements of a planned CE-entity with a known configuration at a given location, comprehensive information is needed (1) on the infrastructure available, (2) where other usable CE-entities are situated, and (3) which qualities and respective quantities they offer. This may be, to name few, separate sewerage equipped buildings able to deliver grey water or facilities with excess heat on the output side; or entities which accept organic waste as input, e.g. biogas plants.

A site resource inventory using different data would unveil urban sources available on a given site to support business location decisions. One data source for a site resource inventory is the geodata infrastructure maintained by the authorities, e.g. the Berlin Geodata Portal. Information is centrally collected and published; but that comes with some restrictions: a rather fixed information structure, low update rate, and no means for user conducted error corrections. A further data source is volunteered geographic information as provided by OpenSteetMap (OSM), where every user can add and change content. OSM relies heavily on tags which describe specific features of map elements, but the standard tags of OSM are of only little use for the CC. Recently an ongoing project on OSM improve the semantic granularity by the introduction of specific CE-tags. This CE-project puts the main focus on locations. But there is further need for extending the range of the tags to enable CC siting by supporting attributes of CE-entities with regard to their material flows. 

The CC food sector and likewise urban agriculture (UA) bears potential towards sustainability if resource efficient food production technologies are used as CE-entities such as aquaponics, the coupled production of fish and vegetables.

Agriculture In the rural environment often uses single-story buildings which are inappropriate in urban contexts where low land consumption is required. On the next level, the roofs, there is much unused space available but competing claims are made, such as green roofs, recreation, housing, thermal and photovoltaic solar use as well as UA solutions like greenhouses. Urban aquaponics as a CE-entity is used exemplarily to propose OSM tags which can evolve to a CE tagging system - thus manifesting a new geodata management approach for a circular city.

How to cite: Baganz, G., Baganz, D., Staaks, G., and Kloas, W.: A missing link - site resource inventories for the circular city, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9171, https://doi.org/10.5194/egusphere-egu2020-9171, 2020.

EGU2020-1834 | Displays | ERE1.4

Closing urban resource cycles through nature-inspired systems

Maria Wirth and Johannes Kisser

The present-day urban system is characterised by a one-directional flow of resources from the rural environment into cities. Cities are centres of human and economic activity, but also of resource use and waste. Therefore, they play both a critical and promising role to support the transition to a circular economy, by keeping incoming products, materials and resources in use. This requires a redesign of biological and technical material cycles in a way that their value can be maintained at the highest possible level for as long as possible, while at the same time natural systems are restored. How can we rethink urban infrastructures to transform cities from resource sinks into circular resource transformation hubs? And how can nature-inspired systems help us to create circular cities?

alchemia-nova is developing integrated, regenerative systems to close water, nutrient, material and energy cycles in cities, centred around buildings as multifunctional service providers. They include building-integrated nature-based solutions for small-scale on-site wastewater treatment, combined with organic solids management to platform chemicals, biogas and nutrients. This approach can enable the efficient valorisation of the high resource potential of urban nutrient flows, with near zero-energy and chemical input. This way, they provide a more efficient, robust and resilient alternative to the predominant chemical and energy-intensive end-of-pipe approaches to circular cities. Water and nutrients can be safely reused in urban and peri-urban agriculture, renewable energy produced on site, biomass and other solid waste further processed to secondary materials, while also gaining the multifunctional benefits of urban greening. These systems are being demonstrated through the EU H2020 HOUSEFUL project in Austria and Spain, complimented by demonstration sites in Greece (EU H2020 HYDROUSA project), thus ensuring their applicability in highly industrialised infrastructure and temperate climatic conditions, as well as in less developed communal infrastructure and Mediterranean arid climatic conditions. HOUSEFUL’s integrated management approach includes circular materials management along the entire housing value chain, e.g. to enable local sourcing of building materials. Together, the robust, low-maintenance technologies and circular materials management contribute to the creation of distributed resource transformation hubs across cities, where value is maintained, and secondary resources captured and recirculated where they occur, creating more efficient and more resilient circular cities, and a wider circular economy.

The research conducted in preparation of this presentation as well as the participation at NGU 2020 is funded by the EU-funded HOUSEFUL project (Grant Agreement number 776708).

HOUSEFUL online: http://houseful.eu/solutions/searching-local-building-material/

How to cite: Wirth, M. and Kisser, J.: Closing urban resource cycles through nature-inspired systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1834, https://doi.org/10.5194/egusphere-egu2020-1834, 2020.

EGU2020-787 | Displays | ERE1.4 | Highlight

Towards Eco-circular economy worldwide

Sergiu Șișcan

Nowadays the global ecological crisis continues aggravating. The environmental issues are on agenda, getting increased public attention (e.g. protests caused by waste problems and climate change all around the world). Depleting resources, trash mountains, garbage islands, toxic emissions etc. require change of economy model from linear (resource extraction-production-usage-throwing away) to the circular one (recycled resource-production-usage-recycling). More than that, multiple waste use as well as resources reuse may bring to business and economy billions of dollars.

The very idea of recycle is practiced in the world since long ago. However, it has been done by few resources (collection of waste paper, scrub metal, glass bottles etc.) without shaping an economic system as a whole.

Another problematic issue is that the recycling does not always means to be ecological. The mode of recycling in countries with low eco-standards results in heavy pollution (e.g. e-waste “recycling” by fire at open air in Africa, India leads to emission of toxins; ship recycling in Bangladesh leads to polluted beaches and water). Methods of recycling in developing countries often are primitive and may be dangerous. Sometimes, entrepreneurs from developed countries are responsible for such state of affairs. They send legally or illegally part of wastes for that primitive recycling in developing countries. It is important to have awareness of the fact that everything is interdependent. If one part of the Earth is full of toxins and harmful fumes, its other part is inevitably affected over time. It is necessary to carry out recycling in all countries establishing strict environmental laws worldwide, and to make it based on smart technologies.

Circular economy in its narrowest sense is an economy that simply processes waste.
A serious change in business models, public mentality and government policies is necessary to get to environmentally friendly economy. It aims at lengthening the use cycle of goods (e.g. clothes, mobile phones) and minimizing the personal waste of every citizen. The EU household’s food waste was estimated to be 47 million tons (EU FUSIONS, 2016). “More than 30% of clothes in Europeans’ wardrobes have not been used for at least a year. Once discarded, over half the garments are not recycled but end up in mixed household waste and are sent to incinerators or landfill” (EPRS, 2019). YouGov Omnibus research: a third (34%) of respondents of Singapore have thrown away an item of clothing after wearing it just once. (YouGov, 2017).

Thus, effective circular economy is not just about re-processing and saving resources but, first, emphasizes its focus on greening environment and reducing waste as it is, becoming an eco-circular economy. Secondly, it calls forth measures at not only national or regional level, but also proceeding from “Earth is our common home”, worldwide.

How to cite: Șișcan, S.: Towards Eco-circular economy worldwide, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-787, https://doi.org/10.5194/egusphere-egu2020-787, 2020.

EGU2020-3855 | Displays | ERE1.4

Rethinking the production and consumption on the transition

Heikki Ruohomaa, Vesa Salminen, and Tapani Pöykkä

Abstract. The new opportunities offered by technologies have caused societies to break through towards the fourth industrial transformation. It will change the whole society and its structures alongside the business and the transition process is still speeding. The world is also facing big megatrends like global warming, urbanization, digitalization, new revolutionary technologies.

Like the industrial revolutions before, the whole paradigm of society is changing, and it will happen also in the fourth industrial revolution, so there is a need to think how we should take a step towards to the new paradigm, so that we could be able to response to future challenges on sustainable way.

The fourth industrial revolution (4IR) technologies like sensor, IoT-platforms, artificial intelligence etc., give new possibilities to develop new, more efficient, more sustainable and more customer driven supply chain, prolong the lifetime of products and create new services and business models and this way reduce the use of materials of energy. There is also an argument to rethink the source of raw material, and in which extent the cities itself could be seen the source of needed materials and energy, by using new technology.

The move towards new ICT based technologies will happen unexpected fast, including exponential growth of data. That is the reason, why it is essential to understand the challenges of change and have a strategic view, identify the key elements and see the new opportunities in all levels of society development.

Circular Economy has been very much a hot topic in many discussions, but there has been quite little discussion about reengineering the value chains and production based on circular economy principles by using the new opportunities on 4IR technologies not only in production but also in creating service, which change the need/thinking of ownership and build new business models. In addition to this, the elements to improve business environment by local or national authorities and legislators.

Finland has is as a goal to develop to one of the leading countries in circular economy, In Finland, Forssa region is considered to be one of the most advanced region in bio-based circular economy.

In this article has been described the development of regional industrial symbiosis in order to have competitive of business and future development.

How to cite: Ruohomaa, H., Salminen, V., and Pöykkä, T.: Rethinking the production and consumption on the transition, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3855, https://doi.org/10.5194/egusphere-egu2020-3855, 2020.

Klaus Wagner, Sigrid Egartner, Heidelinde Grüneis, Karin Heinschink, Julia Niedermayr

Federal Institute of Agricultural Economics, Rural and Mountain Research

Dietrichgasse 27, 1030 Vienna, Austria

Tel: +43 1 71100 637426, Contact: klaus.wagner@bab.gv.at, www.bab.gv.at

 

“Living Lab Research Concept in Rural Areas” (LIVERUR) is an EU-H2020 programme funded project, running from 2018 to 2021. The LIVERUR consortium consists of 23 partners from 13 countries, coordinated by Universida Catolica de Murcia (Spain), see https://liverur.eu.

 

The project aims at modernising small and medium rural businesses in the EU and its neighbouring countries by introducing the Rural Living Lab research methodology. It will identify, analyse and test various specific rural business model approaches. It drafts a new Regional Circular Living Lab Business Model Concept (RAIN) - integrating living lab-, circular economy- and multi-actor approaches as well as open innovation, ecologic, economic and social sustainability with support of innovative ICT solutions. The RAIN concept helps enterprises and organisations to design their sustainable, innovative and contemporary business models.

 

Based on theoretical and empirical analyses the RAIN concept is structured according to three different layers:

  • The Core Elements describe the business model with respect to the topics vision/business idea, people, resources, implementation/development, management/organization, financial aspects, product/service/process, research/innovation, marketing/distribution;
  • In order to enrich the business model the so called RAIN Principles (Ecologic, economic and social sustainability, circular economy, open innovation, stakeholder involvement, openness, ICT) should be taken into consideration in each Core Element;
  • Last but not least, external influences on the project or activity – the Real Life Setting – has to be reflected and included in the business model (environment and climate, economic and societal context, legal and institutional framework, technical and social infrastructure, food security and safety).

 

In LIVERUR 20 projects in 13 pilot regions will be developed based on the RAIN concept. The topics are widespread but all are of high importance in rural regions, e.g. regional food sovereignty, utilization of organic waste, local online-marketing, agriculture-tourism cooperation, sustainable milk-production, energy-production.

 

The contribution will focus on the development and description of the RAIN concept and its steps of application.

 

LIVERUR has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement 773757

How to cite: Wagner, K.: RAIN - A Living Lab Concept for Circular Economy, Cooperation and Innovation in Rural Regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1297, https://doi.org/10.5194/egusphere-egu2020-1297, 2020.

EGU2020-20788 | Displays | ERE1.4

Transdisciplinary research towards transsectoral implementation

Martin Regelsberger, Astrid Allesch, Benedikt Becsi, Verena Germann, Georg Gratzer, Astrid Gühnemann, Laura Hundscheid, Annemarie Körfgen, Christian Kozina, Helmuth Kreiner, Thomas Lindenthal, Maximilian Manderscheid, Sophia-Marie Rammler, Marco Scherz, Ingeborg Schwarzl, Werner Toth, and Harald Vacik

Research is ever deepening its knowledge in a multitude of fields. Such research contributes in great depth to identifying and understanding problems (e.g. in the field of climate change). However, when it comes to societal implementation, it may ultimately lead to zero knowledge at infinite depth, as it has been ironically put. To tackle sustainability, respectively to achieve the 17 sustainable development goals (SDGs) set by the UN, science has to come together and work in transdisciplinary teams. Scientists are poorly prepared for such an exercise and standard procedures of scientific work, sharing and publication of results in specialised conferences and journals do not help.

In view of this problem, the Austrian Alliance of Sustainable Universities and research centres has created a project, UniNEtZ (Universities and Sustainable Development Goals), to jointly address the issues raised by the SDGs and develop suggestions for policies in a multidisciplinary approach. In order to facilitate this for the scientists involved, UniNEtZ is preparing collaborative measures and methods to address the issue of cooperation between disciplines to guarantee that all important interactions among SDGs are considered and addressed in equal detail. It is expected that changes in the way science and scientists are used to work together are necessary to achieve that. The developed concepts will be published in a handbook for UniNEtZ,

In a next step, the  handbook also hints at the need for municipal, regional, and national administrations to transition towards a kind of governance, that enables implementation of policies towards the SDGs. Current hierarchically organised structures don’t seem ideal for the kind of transsectoral cooperation that will be needed to implement the expected measures.

The contribution presents the findings of this work on cooperative research and governance structures.

Keywords: SDGs, Sustainable Development Goals, transdisciplinary research, transsectoral implementation

How to cite: Regelsberger, M., Allesch, A., Becsi, B., Germann, V., Gratzer, G., Gühnemann, A., Hundscheid, L., Körfgen, A., Kozina, C., Kreiner, H., Lindenthal, T., Manderscheid, M., Rammler, S.-M., Scherz, M., Schwarzl, I., Toth, W., and Vacik, H.: Transdisciplinary research towards transsectoral implementation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20788, https://doi.org/10.5194/egusphere-egu2020-20788, 2020.

EGU2020-6097 | Displays | ERE1.4

Transdisciplinary assessments for circular city design: identifying systemic water-energy-food nexus hotspots in metropolitan Barcelona

Cristina Madrid-Lopez, Angelica Mendoza-Beltran, Roc Padro Caminal, Tarik Serrano Tovar, Joan Marull, and Gara Villalba

Green spaces are known to provide a number of benefits to urban areas. In order to make green spaces more accessible to people in urban regions, the EU has launched some important initiatives that place green infrastructure (GI) development as a top priority in urban planning, contributing to the paradigm of making more sustainable and smarter cities for everyone.  However, some GI development might bring unexpected impacts that are observable only with a systemic analysis. For instance, an increased surface of green rooftops might serve as a source of local food production and reduce the need of the buildings’ air conditioning at the expense of increased water and fertilizer use. Despite this shift of focus in urban planning priorities, few studies assess tradeoffs between water, energy and food metabolism of different GI alternatives. An important reason for this gap is that current methods for the analysis of the water-energy-food (WEF) nexus in the urban metabolism lack a transdisciplinary approach.

To fill that gap, we propose using two system analysis methods: Life Cycle Assessment (LCA) and Multi-Scale Integrated Assessment of SocioEcosystem Metabolism (MuSIASEM), to assess the WEF nexus in an urban region in the context of GI. Furthermore, the WEF flows are georeferenced to understand their impact on the urban landscape.  Based on this georeferenced analysis of land use and land use change, we 1) complete an inventory of functions associated to different land uses with their related inputs and outputs, 2) study function-related environmental pressures with LCA, and 3) assess the systemic impacts of relevant functions over domestic and alien ecosystems and WEF supply systems.

We develop this innovative approach using the municipality of Sant Climent de Llobregat, in the Metropolitan Area of Barcelona (AMB), as a case study. Sant Climent covers 1.6% of the AMB surface and is currently undergoing a GI restructuring process focused on recovering formal agricultural land (currently lost to forest)  for highly profitable cherry production. We provide a systemic study that informs about the resource demand and environmental impacts these changes may imply. Data is compiled in collaboration with regional research centers, from local utility companies, planning offices of different towns, statistical yearbooks for Catalonia and Spain, and LCA databases. The work is an on-going collaboration with the AMB government as it develops the Urban Development Plant (PDU) that will set the land use related urbanism policy guidelines from 2021 on. We present a diagnose of the current state of the WEF metabolism in Sant Climent. We identify geographically explicit hotspots, where competition of the resources and unexpected domestic or alien environmental impacts arise.  These hotspots are compared against land to be transformed to highlight the best and worst areas for transformation. We expect that in a later stage, these results will feed a scenario assessment of the systemic impacts of the proposed actions of the new PDU.

This work is part of the research developed in the ERC Project URBAG: Integrated System Analysis of Urban Vegetation and Agriculture.

How to cite: Madrid-Lopez, C., Mendoza-Beltran, A., Padro Caminal, R., Serrano Tovar, T., Marull, J., and Villalba, G.: Transdisciplinary assessments for circular city design: identifying systemic water-energy-food nexus hotspots in metropolitan Barcelona, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6097, https://doi.org/10.5194/egusphere-egu2020-6097, 2020.

EGU2020-17956 | Displays | ERE1.4

The Role of Multi-scale Approach in Planning and Design of Circular Cities: Mapping the Nexus Between Urban and Natural

Jelena Ristic Trajkovic, Verica Krstic, and Aleksandra Milovanovic

The focus of this research is how a multi-scale approach in geospatial information and mapping can contribute to the planning and design of more connected, inclusive, healthy, climate-friendly, and multi-functional circular urban environments. The research addresses the relation between socio-ecological and economic aspects of city development on different spatial levels as a key challenge of European cities. This requires a multidisciplinary and integrative approach to produce effective strategic scenarios of urban development. This methodology is focused on multi-scale analyzes of environmental relationships and provides a flexible framework for improvement of the planning and design of circular cities. Through these advantages, the applied methodology can allow for more flexible identification and improvement of nexus between urban and natural.

One of the basic problems for achieving circularity in urban development is the discontinuous and unplanned urbanization. Such developmental characteristics of cities, as well as the increasing need for nature and biodiversity in cities, necessitated the search for new ecological approaches and principles for their implementation in the process of spatial planning and urban design.  The central research question in the context of sustainable spatial development has become how to ensure multiple balances in-between social, cultural and economic versus ecological systems.

In order to improve the existing circularity and built-natural relations, it is necessary to develop a more complex mapping system which involves planning systems of smaller-scale natural-ecological units integrated into the existing urban structure and connecting them with linear natural-ecological elements. In this sense, the multi-scale methodology is not only reflected in the evaluation of the current situation but also can be used as a tool for testing the variant development opportunities toward circular cities.

The applicability of the developed methodology has been tested within the spatial framework of Belgrade, while the result is a series of critical maps illustrating the nexus between urban and natural in the city.

Acknowledgment: This research was realized as a part of the project “Research and systematization of housing development in Serbia in the context of globalization and European integrations for the purpose of improving housing quality and standards” (TR36034) financed by the Ministry of Education and financed by the Ministry of Education and Science of the Republic of Serbia and COST Action CA17133 - Implementing nature-based solutions for creating a resourceful circular city.

How to cite: Ristic Trajkovic, J., Krstic, V., and Milovanovic, A.: The Role of Multi-scale Approach in Planning and Design of Circular Cities: Mapping the Nexus Between Urban and Natural, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17956, https://doi.org/10.5194/egusphere-egu2020-17956, 2020.

EGU2020-10290 | Displays | ERE1.4

Improving The Municipal Solid Waste Management Plan Of The Municipality Of Nemocón (Colombia)

Camilo Andrés Vargas Terranova and Javier Rodrigo Ilarri

IMPROVING THE MUNICIPAL SOLID WASTE MANAGEMENT PLAN OF THE MUNICIPALITY OF NEMOCÓN (COLOMBIA)

CAMILO-ANDRÉS VARGAS-TERRANOVA(1) and JAVIER RODRIGO-ILARRI(2)

(1)Universidad de La Salle, Bogotá, Colombia (cvterranova@unisalle.edu.co)

(2)Instituto de Ingeniería del Agua y del Medio Ambiente (IIAMA), Universitat Politècnica de València, Spain (jrodrigo@upv.es)

 

ABSTRACT

The municipality of Nemocón (Colombia) located 45 km from Bogotá generates 810.3 t/year of municipal solid waste (MSW). Despite the Colombian national legal requirements, Nemocón Solid Waste Management Plan (SWMP) shows important deficiencies in the waste management system, especially concerning the final destination of waste.

During 2019 a set of activities have been performed in the town as an initial response to these needs with the participation of the community and local authorities. First, the design of the waste collection routes was analyzed and improved. Two routes were designed, supported by compacting vehicles with an average time of 3 hours (80 km per route) and 3 routes per week each. Besides, two shorter routes were designed for the collection of recyclable waste, supported by hand-drawn vehicles, with operating times of 6 hours (8-10 km per route) and daily routes.

With the support of students from the University of La Salle and the donation of an abandoned building, a Classification and Use Station (CUS) was implemented to strengthen the management of such recyclable waste. The CUS was provided with personal protection elements to improve their condition as managers of minor routes and the preliminary treatment of waste in the CUS, for later sale to wholesalers external managers.

Finally, a tax system was designed to finance the operation of the CUS (2500-2800 Euros/month) and promote greater separation volumes in the midterm, based on an adjustment to the normal payment made by the users for the service of waste collection and management. This system took into account the different types of users (commercial, industrial, residential and official), local socioeconomic scale and national economic variables. The increased rate varies between 1 and 1.5% for all users in the first year of increase.

How to cite: Vargas Terranova, C. A. and Rodrigo Ilarri, J.: Improving The Municipal Solid Waste Management Plan Of The Municipality Of Nemocón (Colombia), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10290, https://doi.org/10.5194/egusphere-egu2020-10290, 2020.

EGU2020-10745 | Displays | ERE1.4

Methodological analysis for decision-making regarding solid waste management in megacities

Johanna Solano, David Orjuela Yepes, and Javier Rodrigo-Ilarri

Pronosticar la generación de residuos sólidos se ha convertido en un tema fundamental para dimensionar los elementos técnicos (generación, recolección, transporte, transferencia, uso y disposición final) y políticos (legislación, grupos de interés, sostenibilidad financiera) con respecto a la gestión integral de residuos sólidos en megaciudades. Para poder hacer este tipo de predicciones, es necesario diseñar modelos matemáticos que permitan el análisis de cada variable asociada con esta gestión, teniendo en cuenta las particularidades y necesidades locales de gestión de residuos.

Se pueden incluir varios modelos en cada etapa de la gestión integral de residuos sólidos urbanos. Actualmente, existen modelos que utilizan inteligencia artificial para pronosticar la generación de residuos sólidos urbanos, diseñar rutas de recolección y seleccionar el tipo de disposición final. Sin embargo, es necesario integrar estos modelos que respondan al contexto de cada población. Para lograr esto, es necesario conocer las características de cada ciudad, así como las diferentes variables implícitas dentro del proceso para desarrollar metodologías concretas, que se convierten en herramientas útiles para las administraciones municipales. Sin embargo, las metodologías existentes no incluyen un análisis de los impactos asociados con cada etapa del proceso de gestión de residuos, como criterio para seleccionar las mejores estrategias de gestión. 

Therefore, this methodological proposal includes a stage to evaluate the possible impacts caused by the selected alternative, for which a life cycle analysis is proposed as a tool to determine possible environmental, economic and social impacts. This analysis will be carried out by gathering the corresponding information, as well as using specific software to obtain the data that feeds the model for subsequent decision-making.

Esta propuesta introduce diferentes tipos de modelos en cada etapa del proceso para obtener resultados integrales y más precisos con respecto a las necesidades de una megaciudad. La propuesta se basa en variables y datos reales de acuerdo con las particularidades de las ciudades, para minimizar los posibles errores en la toma de decisiones. Al introducir herramientas cuantitativas para analizar la gestión de residuos sólidos urbanos, la metodología propuesta omite posibles evaluaciones cualitativas o basadas en la percepción, lo que lleva a que los resultados obtenidos sean cada vez más realistas, ya que tienen en cuenta las necesidades reales de cada población.

How to cite: Solano, J., Orjuela Yepes, D., and Rodrigo-Ilarri, J.: Methodological analysis for decision-making regarding solid waste management in megacities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10745, https://doi.org/10.5194/egusphere-egu2020-10745, 2020.

EGU2020-10191 | Displays | ERE1.4

The removal of As(V) ions by lime-modified fly ash and reuse of the exhausted adsorbent as an additive for construction material

Milica Karanac, Maja Đolić, Vladimir Pavićević, and Aleksandar Marinković

Coal thermal power plants (TPP) actively generate numerous solid combustion by-products, including fly ash and bottom ash. These TPP by-products have already found use in a variety of civil engineering applications, such as a substitute for sand and gravel in structures, as well as a binding component in certain types of cement (generally, concrete and masonry). Furthermore, such by-products have become a subject of increasing interest in environmental engineering as a low-cost and effective adsorbent for the removal of organic pollutants and heavy metals from wastewaters.

In order to minimize the impact of material cost, novel solutions for the development of a high capacity and long-term adsorbent have provided a high performance adsorbent for practical applications. This study is focused on the use of modified fly ash (MFA) activated by lime (Ca(OH)2) as an effective and low-cost adsorbent for the removal of As(V) ions. The adsorption capacity of the MFA adsorbent was found to be 35.40 mg g-1, while the kinetic and thermodynamic parameters indicated a spontaneous and endothermic process. Due to the low desorption potential of the exhausted adsorbent (MFA/As(V), their effective further material reuse was established to be feasible. The reuse of the exhausted adsorbent was obtained through pozzolanic MFA particles and Ca(OH)2, thereby formulating a construction material of a cementitious calcium-silicate hydrate. The toxicity leaching test (TCLP) and mechanical properties of the new construction material containing exhausted MFA (CM-MFA/As(V)) confirm its safe use in the laboratory as well as its semi-industrial application.

The specific objectives of this study have been: (i) to improve the adsorption performance of the MFA; (ii) to evaluate the material’s equilibrium, as well as the process’ kinetic and thermodynamic aspects, including  estimating its limiting step; and (iii) to investigate the possible reuse of the exhausted adsorbent in the production of construction materials. The kinetic data were successfully fitted by a pseudo-second-order equation and the Weber-Morris model. The metal-desorption experiments performed on the exhausted FA and MFA indicate a low recovery of the selected pollutants.

The major outcome of this study, indicates that double-valorization of fly ash opens new directions for waste management toward reuse in effective practical applications; i.e., for actual water –purification systems, as well as in the production of construction material.

How to cite: Karanac, M., Đolić, M., Pavićević, V., and Marinković, A.: The removal of As(V) ions by lime-modified fly ash and reuse of the exhausted adsorbent as an additive for construction material, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10191, https://doi.org/10.5194/egusphere-egu2020-10191, 2020.

EGU2020-493 | Displays | ERE1.4

Lignin microspheres as a nature-based material for effective nickel(II) and cadmium(II) ions removal

Tijana Stanišić, Ana Popović, Jelena Rusmirović, Maja Đolić, Mirjana Ristić, Aleksandra Perić-Grujić, and Aleksandar Marinković

Sustainable development and the circular economy are becoming the new imperative of industrial growth, as the world faces the depletion of natural resources and consequences of climate change. The utilization of waste streams through the concept of ‘new added value’ gives life to the production of materials and their environmental application. Therefore, the development of novel, eco-friendly, nature-based adsorbents that possess high degradable and recyclable potential is on the forefront of research. The modifications of wood derivates, such as cellulose and lignin, are widely applied as natural polymers due to their economic feasibility, ecological similarity and adsorption capabilities.

The subject of this study is the adsorption of nickel(II) and cadmium(II) ions from aqueous solutions using 5.0 mass % of alginate lignin microspheres (A-LMS). Due to their toxicity, persistence, high solubility and mobility, such heavy metals are widely dispersed throughout environmental media (chiefly, aquatic bodies), leading to ecological and public health problems. The raw lignin used as a source material in the study originates from the waste stream of the lumber industry. The porous microspheres are of a radius of 50 to 950 microns and a surface area of 36.9 m2 g-1 were synthesized via inverse suspension copolymerization of the kraft lignin with a poly(ethylene imine) grafting-agent and an epichlorohydrin cross-linker. The structural and surface characteristics were confirmed via Fourier transform-infrared (FTIR) spectroscopy, x-ray diffraction (XRD) and scanning electron microscopy (SEM). The textural properties of the synthesized A-LMS were determined according to the Brunauer, Emmett and Teller (BET) method of analyzing nitrogen adsorption. The adsorption batch and column testing were carried out by varying the reaction time, temperature, adsorbent mass, at predefined pH values of the initial solutions. The maximum adsorption capacity of the A-LMS for nickel (II) ions was 89.286 mg g-1 at a temperature of 318 K, while for the adsorption of cadmium(II) ions it was 96.154 mg g-1 at a temperature of 308 K. The kinetic data followed the pseudo-second-order kinetic model, while the Weber-Morris model indicated intra-particle diffusion as a rate limiting step. The thermodynamic parameters for the A-LMS further confirm that the adsorption process was spontaneous and endothermic.

The study indicates the high potential of by-products or waste products from heavy industry to be repurposed for environmental engineering applications by which they may serve a benefit as opposed to being a detrimental risk. Such is the case here with lignin-natural polymers taken from the lumber industry, which themselves may be reutilized for the removal of heavy metals from wastewater.

Acknowledgments

This work was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (project no. 172007). The authors would like to acknowledge the financial support provided by COST-European Cooperation in Science and Technology, to the Cost Action CA17133: Circular City.

How to cite: Stanišić, T., Popović, A., Rusmirović, J., Đolić, M., Ristić, M., Perić-Grujić, A., and Marinković, A.: Lignin microspheres as a nature-based material for effective nickel(II) and cadmium(II) ions removal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-493, https://doi.org/10.5194/egusphere-egu2020-493, 2020.

EGU2020-4223 | Displays | ERE1.4

How to meaningfully engage key stakeholders in smart circular economy

Gergana Majercakova and Sabina Bokal

As an alternative to the traditional linear economy, the circular economy could help tackle the climate emergency, decrease resource scarcity and increase business sustainability. Implementing it successfully, maintaining sustainability and facilitating real systemic change means an effective coordination among all stakeholders is needed.

Meaningful engagement of stakeholders will help achieve a shared understanding of the concept, the new approaches and their implementation at all levels. Mobilizing different stakeholders is always a challenge and requires careful planning in order to demonstrate that the stakeholders’ input and engagement is valued, and participatory processes are in place.

The presentation will provide insights into the different stakeholder groups, their interests and methods that could be employed to reach effective engagement. It will also outline approaches, actions and tools that should help circular economy drivers develop a plan for stakeholder engagement based on clear understanding of stakeholders’ needs.

Apart from the general insights on the role of stakeholders in circular economy projects, the presentation will also provide practical knowledge on mapping and profiling stakeholders, stakeholder engagement strategy development, engagement tools and evaluation methods. Specific needs for improvement of stakeholder engagement practices into Circular economy projects will be tackled and discussed as well.

How to cite: Majercakova, G. and Bokal, S.: How to meaningfully engage key stakeholders in smart circular economy , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4223, https://doi.org/10.5194/egusphere-egu2020-4223, 2020.

The welfare of the Republic of Moldova much depends on the use of its natural resources. However, the pace at which the natural resources are exploited exceeds the ability of the environment to regenerate them. Land resources are the main natural wealth of the country. The conservation and increase of effective fertility of the soils becomes the basic task of the owners of agricultural lands. The methods of the conventional agriculture do not work anymore to make the sector competitive at regional and global markets. New concepts and technologies of Green and Circular economy are of more perspective. They also are more effective under the continuous unbalanced extraction of natural resources which causes environmental damage.

The case of Moldova reflects the global trends. Some international studies have shown that the global consumption of materials per capita has doubled, while the consumption of primary energy has tripled in the last hundred years. In other words, each of us consumes three times as much energy and twice as much material as our predecessors consumed in 1900. Moreover, nowadays there are 7.2 billion consumers compared to 1.6 billion in 1900.

At the same time, the requirements for quality standards in Green economy are very high and rigid as well as  “the annual financing demand to green the global economy has been estimated to be in range 1.05 USD to 2.59 USD trillion” (UNEP, 2011). That is why the Circular ecological economy is seen as more viable solution for world, regional and national economies. ”Ecological economy” generally refers to an economy in which all the choices regarding production and consumption are made taking into account the welfare of the society and the global health of the environment. ”Circular economy” implies a system of production and consumption that generates as little loss as possible.

The EU Circular economy Package and CE Stakeholder Platform are a good start for regional economy as well as that of Republic of Moldova as its Associate Member. The beneficial solution for improving the environment of the country consists in redesigning products, production and consumption processes by minimizing waste and transforming that unused part into a resource.

How to cite: Cojocaru, O. and Siscan, Z.: The circular ecological economy - a beneficial environment in light of the use of natural resources in the Republic of Moldova, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-58, https://doi.org/10.5194/egusphere-egu2020-58, 2020.

EGU2020-18282 | Displays | ERE1.4

The superiority of circular economy solutions in the main sectors of an innovative and prospering economy – a case study from Iceland

David C. Finger, Halldór G. Svavarsson, Bryndís Björnsdóttir, Guðrún A. Sævarsdóttir, and Lea Lea Böhme

Circular economy solutions reuse and upcycle waste streams in order to minimize the use of resources and mitigate the creation of waste and emissions. Accordingly, circular economy solutions are an essential tool to tackle the imminent challenges of depleting resources and the emerging environmental crisis. In this presentation, we explore the circular solutions for resource recovery in waste streams in a country with one of the highest Gross Domestic Product (GDP) and Human Development Index (HDI) in Europe, Iceland. The economy of Iceland is mainly based on renewable energy, fishery, farming, metallurgy, and tourism. To assess the benefits of circular economy solutions we examine four relevant case studies from the following industrial sectors in Iceland: i) a geothermal energy plant, ii) fisheries, iii) domestic waste processing and iv) aluminium production. By describing the processes, the opportunities and the market potential of the circular economy solutions in the four case studies we identify the superiority of circular recovery of resources in a modern society. The results reveal that the recovery of resources reduces the environmental impacts, increases the economic output and enhances the resilience of the local economy. While our results are based on the examples in Iceland the described processes of resource recovery can be applied in any other country with similar resources. We conclude that the presented circular solutions could lead to a more sustainable world while preserving vital resources for the next generations.

How to cite: Finger, D. C., Svavarsson, H. G., Björnsdóttir, B., Sævarsdóttir, G. A., and Lea Böhme, L.: The superiority of circular economy solutions in the main sectors of an innovative and prospering economy – a case study from Iceland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18282, https://doi.org/10.5194/egusphere-egu2020-18282, 2020.

EGU2020-1816 | Displays | ERE1.4

Emission of primary microplastics in mainland China: Invisible but not Negligible

Teng Wang, Baojie Li, and Xinqing Zou

Emission of primary microplastics in mainland China: Invisible but not Negligible

 

Teng Wang 1,3, Baojie Li 2,3* , Xinqing Zou3*

1 College of Oceanography, Hohai University, Nanjing, 210098

2 School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, 210044

3 School of Geography and Ocean Science, Nanjing University, Nanjing, 210023

  

Abstract:

Primary microplastics are mostly produced as part of the daily plastic product use. The emission process is often invisible but poses potential ecological hazards. Thus, primary microplastics deserve public attention. Due to China's huge population base and its rapid economic development, primary microplastics emissions are of both regional and global significance. This study is the first to establish the emission inventory of primary microplastics in mainland China. It was estimated that the primary microplastic waste from mainland China amounts to 737.29 Gg, and one-sixth of this amount entered the aquatic environment in 2015. The highest proportion of this waste was attributable to tire dust and synthetic fiber, accounting for 53.91% and 28.77% of the total respectively, in mainland China. The primary microplastics emissions mainly depend on the population, followed by the level of economic development. It was roughly estimated that 538 g of microplastics is produced by each person in China. At the grid scale, the spatial difference in the total primary microplastics emissions in mainland China primarily depends on the population density distribution and transportation network. We studied the entire life cycle of several sources of microplastics, from production to discharge into the aquatic environment. We suggested different control measures under different nodes. Increasing microplastics treatment in sewage treatment plants should be a short-term viable way to achieve some measure of reduction in their entry to the environment in mainland China. Our research can not only raise public awareness about primary microplastics, but can also guide the development of environmental policies to reduce plastic pollution.

 

Keywords: Primary microplastics; Emission inventory; Mainland China; Sewage treatment plants

How to cite: Wang, T., Li, B., and Zou, X.: Emission of primary microplastics in mainland China: Invisible but not Negligible, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1816, https://doi.org/10.5194/egusphere-egu2020-1816, 2020.

ERE2.1 – Energy Meteorology

EGU2020-8452 | Displays | ERE2.1

Local microclimatic impacts of utility scale photovoltaic solar parks

Alona Armstrong, Rebecca R Hernandez, George A Blackburn, Gemma Davies, Merryn Hunt, James D Whyatt, and Li Guoqing

Solar photovoltaic (PV) capacity has risen exponentially, with the majority deployed as ground-mounted solar parks, across the world. Deployments are projected to continue, leading to further land use change with implications for the hosting environment, including perturbations in ecological processes that underpin the supply of natural capital and ecosystem services. Whilst alterations to within solar park climate of magnitudes known to effect ecosystems processes have been quantified, the spatial extent remains unclear. In this study, we use remote sensing and field data to provide evidence of a solar park land surface temperature (LST) cool island. Specifically, we quantify a LST cooling of up to 2.3 ℃ outside the solar park boundary, with the effect declining rapidly with distance from the solar park but extending up to 730 m away. The magnitude of cooling observed is sufficient to alter ecosystem processes, including greenhouse gas emissions with implications for the carbon intensity of the electricity produced. Consequently, we need to better understand the local climatic impacts of solar parks and associated cascading impacts on ecosystem function to establish the broader environmental co-benefits and costs of this rapidly growing means of low carbon electricity production.

How to cite: Armstrong, A., Hernandez, R. R., Blackburn, G. A., Davies, G., Hunt, M., Whyatt, J. D., and Guoqing, L.: Local microclimatic impacts of utility scale photovoltaic solar parks , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8452, https://doi.org/10.5194/egusphere-egu2020-8452, 2020.

EGU2020-18797 | Displays | ERE2.1

Impact of weather regimes on wind power variability in western Europe

Ricardo García-Herrera, Jose M. Garrido-Perez, Carlos Ordóñez, David Barriopedro, and Daniel Paredes

We have examined the applicability of a new set of 8 tailored weather regimes (WRs) to reproduce wind power variability in Western Europe. These WRs have been defined using a substantially smaller domain than those traditionally used to derive WRs for the North Atlantic-European sector, in order to maximize the large-scale circulation signal on wind power in the region of study. Wind power is characterized here by wind capacity factors (CFs) from a meteorological reanalysis dataset and from high-resolution data simulated by the Weather Research and Forecasting (WRF) model. We first show that WRs capture effectively year-round onshore wind power production variability across Europe, especially over northwestern / central Europe and Iberia. Since the influence of the large-scale circulation on wind energy production is regionally dependent, we have then examined the high-resolution CF data interpolated to the location of more than 100 wind farms in two regions with different orography and climatological features, the UK and the Iberian Peninsula.

The use of WRs allows discriminating situations with varied wind speed distributions and power production in both regions. In addition, the use of their monthly frequencies of occurrence as predictors in a multi-linear regression model allows explaining up to two thirds of the month-to-month CF variability for most seasons and sub-regions. These results outperform those previously reported based on Euro-Atlantic modes of atmospheric circulation. The improvement achieved by the spatial adaptation of WRs to a relatively small domain seems to compensate for the reduction in explained variance that may occur when using yearly as compared to monthly or seasonal WR classifications. In addition, our annual WR classification has the advantage that it allows applying a consistent group of WRs to reproduce day-to-day wind speed variability during extreme events regardless of the time of the year. As an illustration, we have applied these WRs to two recent periods such as the wind energy deficit of summer 2018 in the UK and the surplus of March 2018 in Iberia, which can be explained consistently by the different combinations of WRs.

How to cite: García-Herrera, R., Garrido-Perez, J. M., Ordóñez, C., Barriopedro, D., and Paredes, D.: Impact of weather regimes on wind power variability in western Europe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18797, https://doi.org/10.5194/egusphere-egu2020-18797, 2020.

EGU2020-20614 | Displays | ERE2.1

Impact of blocking on low wind events and its representation by high-resolution GCMs: An energy perspective

Paula Gonzalez, David Brayshaw, and Reinhard Schiemann

With higher penetration of renewable energies and the effort to decarbonize power production there is a strong interest in the objective characterization of wind resource. Over Europe, wind power accounts for around 17% of total power capacity and almost 30% of renewable capacity and is the overall second largest form of generation capacity after gas. 

In addition to the description of mean capacity factors, there is a need to characterize extremes. Low wind events and persistent low wind events (LWE) are of particular interest because during these the energy system needs to rely on ‘backup’ sources such as gas, coal and nuclear. Over the United Kingdom and other parts of Europe, these are often linked to the occurrence of blocking (e.g., Brayshaw et al. 2012, Cannon et al. 2015, Grams et al. 2017), which is the initial focus of this study. Additionally, blocking events have an impact on near-surface temperatures over Europe, which implies an effect in weather-dependent energy demand. 

This study focuses on the impacts of blocking conditions on low wind events and their persistence, and the representation of these effects on the high-resolution (around 25km) global PRIMAVERA models. Our results confirm that blocking events over Europe have a significant impact on the occurrence and duration of low wind speeds at the country level, which is of relevance to the energy sector. In addition to becoming more frequent, LWE are also more persistent under blocking conditions over large areas of Europe. Both effects are in general captured by most of the PRIMAVERA GCMs analysed here, revealing that when the models do get the blocking events, the basic dynamical connection with wind anomalies is present. Nonetheless, the fact that the simulated weather conditions have deficiencies introduces biases in the properties of the events and their joint occurrence.  

The errors in the models depend on the statistic, the country and the resolution, but some consistent bias patterns can be observed at times (e.g., North-South dipolar structures). No robust improvements in the representation of these effects were observed in the high-resolution versions of the PRIMAVERA models, nor where the highest resolution runs consistently outperforming coarser simulations.  

Blocking impacts to the energy systems are not only limited to wind power generation, since these large-scale anomalies also have an impact on near-surface temperature and therefore on electricity demand. These effects are also addressed here.

How to cite: Gonzalez, P., Brayshaw, D., and Schiemann, R.: Impact of blocking on low wind events and its representation by high-resolution GCMs: An energy perspective , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20614, https://doi.org/10.5194/egusphere-egu2020-20614, 2020.

EGU2020-19846 | Displays | ERE2.1

The European wind from observational and simulated databases

Elena García-Bustamante, Jorge Navarro, Jesús Fidel González-Rouco, E. Etor Lucio- Eceiza, Cristina Rojas-Labanda, and Ana Palomares

The New European Wind Atlas (https://map.neweuropeanwindatlas.eu) is developed based on the simulated wind field over Europe from a mesoscale model coupled to a microscale component through a statistical downscaling approach. The simulation that provides mesoscale inputs within the model chain has been decided upon a careful sensitivity analysis of potential model configurations. In order to accomplish model resolutions of 3 km over Europe, the broader European domain is partitioned into a set of 10 partially overlapping tiles. The wind field is simulated with the WRF model over these tiles and finally blended into a single domain. The wind outputs from a reference simulation is evaluated on the basis of its comparison with an observational database specifically compiled and quality controlled for the purpose of validating the wind atlas over the complete European domain. The observational database includes surface wind observations at ca. 4000 sites as well as 16 masts datasets. The observational dataset of surface wind (WISED) is informative about the spatial and temporal variability of the wind climatology, punctuated with singular masts that provide information of wind velocities at height. The validation of the mesoscale simulation aims at investigating the ability of the high-resolution simulation to reproduce the observed intra-annual variability of daily wind within the entire domain.

Observed and simulated winds are higher at the British, North Sea and Baltic shores and lowlands. Correlations are typically over 0.8. Surface wind variability tends to be overestimated in the northern coasts and underestimated elsewhere and inland. Mast wind variability tends to be overestimated except for some southern sites. Seasonal differences seem minor in these respects. Biases and RMSE can help identifying if systematic errors in specific tiles take place.

Therefore, performing model simulations of a high horizontal resolution over the broader European domain is possible. We can learn about the variability of surface and height wind both from observations and model simulations. Model observations are not perfect, but observations also present uncertainties. Good quality wind data, both at the surface and in masts are a requisite for robust evaluation of models. European wide features of wind variability can be recognized both in observations and simulations.

How to cite: García-Bustamante, E., Navarro, J., González-Rouco, J. F., Lucio- Eceiza, E. E., Rojas-Labanda, C., and Palomares, A.: The European wind from observational and simulated databases, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19846, https://doi.org/10.5194/egusphere-egu2020-19846, 2020.

EGU2020-10087 | Displays | ERE2.1

Offshore wind farm far field - Results of the project WIPAFF

Andreas Platis, Jens Bange, Konrad Bärfuss, Beatriz Canadillas, Marie Hundhausen, Bughsin Djath, Astrid Lampert, Johannes Schulz-Stellenfleth, Simon Siedersleben, Thomas Neumann, and Stefan Emeis

Wind farm far wakes are of particular interest for offshore installations, as turbulence intensity, which is the main driver for wake dissipation, is much lower over the ocean than over land. Therefore, wakes behind offshore wind turbines and wind parks are expected to be much longer than behind onshore parks. 

In situ measurements of the far wakes were missing before the initiation of the research project WIPAFF (WInd PArk Far Fields) in 2015. The main results of which are reported here. WIPAFF has been funded by the German Federal Ministry for Economic Affairs and Energy and ran from November 2015 to April 2019.  The main goal of WIPAFF was to perform a large number of in situ measurements from aircraft operations at hub height behind wind parks in the German Bight (North Sea), to evaluate further SAR images and to update and validate existing meso-scale and industrial models on the basis of the observations to enable a holistic coverage of the downstream wakes.
 
A  unique  dataset  from  airborne in situ data,  remote sensing  by  laser  scanner  and  SAR  gained  during  the WIPAFF  project  proves  that  wakes  up to  several  tens of kilometers exist downstream of offshore wind farms during stable conditions, while under neutral/unstable conditions, the wake length amounts to 15 km or less. Turbulence occurs at the lateral boundaries of the wakes, due to shear between the reduced wind speed inside the wake and the undisturbed flow. Data also indicates that a denser wind park layout increases the wake length additionally due to a higher initial wind speed deficit. The recovery of the decelerated flow in the wake can be modeled as a first order approximation by an exponential function. The project could also reveal that wind-farm parameterizations in the numerical meso-scale WRF model show a feasible agreement with the observations. 

How to cite: Platis, A., Bange, J., Bärfuss, K., Canadillas, B., Hundhausen, M., Djath, B., Lampert, A., Schulz-Stellenfleth, J., Siedersleben, S., Neumann, T., and Emeis, S.: Offshore wind farm far field - Results of the project WIPAFF, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10087, https://doi.org/10.5194/egusphere-egu2020-10087, 2020.

EGU2020-1646 | Displays | ERE2.1

Estimation of the offshore extreme winds at 100m over JiangSu province based on spectral correction and numerical simulation

Rui Chang, Rong Zhu, Yizhou Yin, Wentong Ma, and Daquan Zhang

Offshore wind power is seen as a large renewable energy resource due to the high and continuous wind speeds over the ocean.However, as wind farms expand in scale, wind turbines increasingly remove kinetic energy from the atmospheric flow, reducing wind speeds and expected electricity yields.Here we show that this removal effect of large wind farms and the drop in yields can be estimated in a relatively simple way by considering the kinetic energy budget of the lower atmosphere, which we refer to as the KEBA approach.We first show that KEBA can reproduce the estimated, climatological yields of wind farms of different sizes and locations using previously published numerical model simulations with an explicit wind farm representation.  We then show the relevance of these reductions by evaluating the contribution of offshore wind energy in specific scenarios of Germany’s energy transition in the year 2050.Our estimates suggest that due to reduced wind speeds, mean capacity factors of wind farms are reduced to 33 - 39%, which is notably less than capacity factors above 50% that are commonly assumed in energy scenarios.This reduction is explained by KEBA by the depletion of the horizontal flow of kinetic energy by the wind farms and the low vertical renewal rate, which limits large-scale wind energy potentials to less than 1 W m-2 of surface area.We conclude that wind speed reductions are likely to play a substantial role in the further expansion of offshore wind energy and need to be considered in the planning process.These reduced yields can be estimated by a comparatively simple approach based on budgeting the kinetic energy of the atmosphere surrounding the wind farms.

How to cite: Kleidon, A. and Miller, L.: Estimating offshore wind power potentials that account for the kinetic energy removal by wind turbines: the Kinetic Energy Budget of the Atmosphere (KEBA) approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4988, https://doi.org/10.5194/egusphere-egu2020-4988, 2020.

EGU2020-10152 | Displays | ERE2.1

Forecasting sub-resolution temporal variability of irradiance

Frank Kreuwel and Chiel van Heerwaarden

Variability of solar irradiance is an important factor concerning large-scale integration of solar photovoltaics (PV) systems onto the electricity grid. Calculations of irradiance are computationally expensive, leaving operational meso-scale forecasting models struggling to achieve accurate results. Moreover, such models deliver outputs at a temporal resolution in the order of hours, whereas from a grid-integration point of view, minute-to-minute variability is a major concern. In previous work, we found that absolute power peaks in the order of seconds are up to 18% higher compared to 15-minute resolution for irradiance and even upwards of 22% higher for household PV systems. Moreover, these maximum peaks in output power are solely observed under mixed-cloud conditions, for which alse the greatest variability is found. In this work we present a machine-learning model which can forecast sub-resolution variability of irradiance, based on standard meso-scale outputs of the HARMONIE model of the The Royal Netherlands Meteorological Institute (KNMI). For training and validation, irradiance measurements obtained at a 1-second interval are used of the Baseline Surface Radiation Network (BSRN) site of Cabauw. A tree-based model was employed, for which the optimum members were constructed using extreme gradient boosting. In this work, we explore the dominant features of the model and link the machine-learned-relations to meteorological processes and dynamics. This research was executed in collaboration with the Distribution Grid Operator Alliander.

How to cite: Kreuwel, F. and van Heerwaarden, C.: Forecasting sub-resolution temporal variability of irradiance, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10152, https://doi.org/10.5194/egusphere-egu2020-10152, 2020.

EGU2020-7187 | Displays | ERE2.1

Front detection using wind park data and NWP

Franz Feldtkeller, Annekatrin Kirsch, Greta Denisenko, and Markus Abel

The precise forecasting of ramps in production of windparks is a problem that is not satifsfactorily solved. This is of particular interest because ramps contribute to a major part to the forecasting error in power production, in particular for offshore wind parks.

Since ramps are often due to fronts passing a location, we developed a method for the correction of front speed and -direction using a combination of wind park meteorological measurements and numerical weather prediction (NWP). On one hand we use conventional methods like the Canny algorithm for NWP data, on the other hand, we use data from a collection of wind parks to determine a passing front. By the front speed, and the relative location of wind parks, the front speed is computed and a correction can  be applied to downstream wind parks.

The results can be  validated and a corresponding error measure can be computed on the basis of measured and numerical data. Our method shall be implemented into a proprietary forecast system with the goal of an automatized detection and correction mechanism.

How to cite: Feldtkeller, F., Kirsch, A., Denisenko, G., and Abel, M.: Front detection using wind park data and NWP, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7187, https://doi.org/10.5194/egusphere-egu2020-7187, 2020.

EGU2020-13790 | Displays | ERE2.1

Short-term photovoltaic generation forecasting using multiple heterogenous sources of data based on an analog approach.

Kevin Bellinguer, Robin Girard, Guillaume Bontron, and Georges Kariniotakis

Abstract

Over the past years, environmental concerns have played a key role in the development of renewable energy sources (RES). In Europe, the installed capacity of photovoltaic (PV) has increased from around 10 GW in 2008 to nearly 119 GW in 2018 [1]. Due to this high penetration rate and the intermittent nature of RES, several challenges appear related to the economic and secure operation of a power system. To overcome these challenges, it is necessary to develop reliable forecasts of RES, and namely of PV production, for the next hours to days to adjust production planning, while intra-hourly forecasts may contribute to optimize operation of storage units coupled to RES plants.

The aim of this paper is to present a novel spatio-temporal (ST) spot forecasting approach able to use multiple heterogeneous sources of data as inputs to forecast short-term PV production (i.e. from 15 minutes up to a day ahead).

First, we consider measured production data from nearby power plants as input to forecast the output of a specific PV plant. These data permit to exploit the correlation between the production data of spatially distributed PV sites. The classical ST approach in the literature, based only on this source of data [2], permits to improve predictability for the next few minutes up to 6 hours ahead.

Then, we extend the model by the use of satellite images (i.e. global horizontal irradiance (GHI)) which provide meaningful spatial information at a larger extent.

Finally, we consider Numerical Weather Predictions (NWPs) as input, which permit to extend the applicability of the model to day-ahead lead times, so that, overall, the resulting model covers efficiently horizons ranging from a few minutes to day ahead.

The spatio-temporal relationships being dependent on the particular meteorological situation of the day at hand, we apply an analog ensemble approach, to condition the learning process with historical observations corresponding to similar meteorological situation. We used the analogue approach to select a subset of similar historical situations over which a dynamical calibration of the forecasted model is done, as it was for example suggested by [3,4]. In our paper we extend the analogs ensemble approach by considering geographically distributed observations of the physical variables of interest (as suggested by [4] for hydrological issues) rather than only those at the level of the PV plant.

The performance of the proposed ST model with heterogeneous inputs is compared with reference models and advanced ones such as the Random Forest model. Historical production data collected from 9 PV plants of CNR are considered. The power units, located in the South-East France, exhibit relevant spatial correlations which make them suitable for the proposed ST model.

 

References

  • [1] IRENA - https://www.irena.org/Statistics/Download-Data
  • [2] Agoua, Girard, Kariniotakis. Short-Term Spatio-Temporal Forecasting of Photovoltaic Power Production. IEEE Transactions on Sustainable Energy , IEEE, 2018, 9 (2), pp. 538 - 546. https://doi.org/10.1109/TSTE.2017.2747765
  • [3] Alessandrini, Delle Monache, Sperati, Cervone. An analog ensemble for short-term probabilistic solar power forecast. Applied Energy, 2015. https://doi.org/10.1016/j.apenergy.2015.08.011
  • [4] Bellier, Bontron, Zin. Using meteorological analogues for reordering postprocessed precipitation ensembles in hydrological forecasting. Water Resources Research, 2017. https://doi.org/10.1002/2017wr021245

How to cite: Bellinguer, K., Girard, R., Bontron, G., and Kariniotakis, G.: Short-term photovoltaic generation forecasting using multiple heterogenous sources of data based on an analog approach., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13790, https://doi.org/10.5194/egusphere-egu2020-13790, 2020.

EGU2020-21753 | Displays | ERE2.1

Towards a seamless approach for photovoltaïc forecasting

Thomas Carriere and Georges Kariniotakis

Trading of photovoltaic (PV) energy generation involves several decision making processes at different times with different objectives. For example, a PV power plant coupled with a Battery Energy Storage System (BESS) has to provide bids in the day-ahead electricity market, but can also provide ancillary services. On the delivery day, it can also participate in intra-day trading sessions, and must decide which quantity to charge or discharge from the BESS in real-time. These successive decision-making processes all require forecasts of the energy production level for different forecast horizons. Besides, such decisions are generally not taken for a single plant at a single location but for a collection of several geographically distributed plants.

However, the models and the inputs used for the different forecast horizons are often different. In situ measurements are more accurate for very-short term forecasts (real-time to one hour ahead forecasts), satellite data is used for short-term forecasts (up to 6 hours ahead), and Numerical Weather Predictions (NWP) are used for long-term forecasts (day-ahead and longer). Models also vary, with auto-regressive approaches being commonly used for very-short term forecasts, while longer forecast horizons use a wide range of machine learning models. PV producers have thus to develop and maintain numerous forecasting models for the different decision-making processes they are involved in, usually fitted for each power plant. This increases further the complexity of the decision-making processes.

In this work we propose a forecasting model that can use all the inputs mentioned before, and weights them according to the forecasting horizon. It can thus operate from very short-term to day-ahead forecast horizons with state-of-the-art performance. It can also directly provide probabilistic forecasts for an aggregation of power plants, thus allowing having a single forecasting model for managing a virtual power plant. The model follows the “lazy learning” paradigm, where generalization from the training set is only computed when a forecast is requested. Thus, the model is resilient to changes in the neighborhood of the plant (surrounding environment, partial outage, soiling, etc.). The model is based on the Analog Ensemble (AnEn) method. However it is structurally expanded to allow the method to use an arbitrary large number of inputs. Each input is then weighted depending on the forecast horizon, which allows dynamically selecting the most relevant inputs depending on the horizon.

The model is evaluated for short-term and day-ahead forecasts, and compared with a Quantile Regression Forest (QRF) and Bayesian Automatic Relevance Determination (ARD) for day-ahead forecasts, and a linear Auto-Regressive Integrated Moving Average (ARIMA) model for short term forecasts. Results show that the AnEn model is competitive with the QRF and ARD models in day-ahead forecasting, while requiring less computational resources and without a need for regular retraining. It is also better than the ARIMA model for short-term forecasting. An evaluation conditional to the the weather variability allow to assess the model performance in the best and worst condition.

How to cite: Carriere, T. and Kariniotakis, G.: Towards a seamless approach for photovoltaïc forecasting, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21753, https://doi.org/10.5194/egusphere-egu2020-21753, 2020.

EGU2020-19081 | Displays | ERE2.1

Forecast trajectories for the production of a renewable virtual power plant able to provide ancillary services

Simon Camal, Andrea Michiorri, and Georges Kariniotakis

The aggregation of multiple renewable plants located in distinct climate zones, using different energy sources, enables to reduce the production uncertainty when compared to the production of a single plant. Such aggregations, controlled by a Virtual Power Plant (VPP) system, are good candidates for the provision of ancillary services. Stochastic optimization models are available to optimize biddings on ancillary services and energy markets (see for instance [1]). These models require trajectories of the renewable VPP production that anticipate production uncertainty and reproduce correctly the temporal correlations observed in the production signal. This is particularly important in ancillary services markets, where a reserve bid must be guaranteed over a production duration or validity period during which power fluctuations are significant (e.g. lasting currently 24 hours on the European common market for Frequency Containment Reserve, with a foreseen evolution to 4 hours by July 2020 [2]). 
Production trajectories may be obtained by coupling probabilistic forecasts and a model of temporal dependencies between forecast horizons [3] and possibly spatial dependencies in the case of a multivariate forecast at the scale of a region or a portfolio [4]. In the case of a renewable VPP, the aggregated production is primarily of interest. In this work, we propose a methodology to generate trajectories of aggregated production from probabilistic forecasts obtained with decision-tree based models or neural networks. A copula models the dependency between forecast horizons and the space defined by the plants contained in the aggregation. The model is tested in a day-ahead forecasting configuration on a 54 MW VPP comprising 15 plants with 3 different energy sources (Photovoltaics, Wind, Hydro). The comparison of trajectories generated from a direct forecast of the aggregated production and from forecasts at lower levels of the aggregation shows that the latter solution reproduces with more accuracy the temporal variability of the aggregated production over the whole horizon range, especially when Photovoltaics dominates the production capacities in the aggregation (15 % improvement of the Variogram Score).
 [1]: Soares, T., & Pinson, P. (2017). Renewable energy sources offering flexibility through electricity markets. Technical University of Denmark.
[2]: ENTSO-E. (2018). TSO’s proposal for the establishment of common and harmonised rules and processes for the exchange and procurement of Balancing Capacity for Frequency Containment Reserves (FCR) TSOs’ proposal for the establishment of common and harmonised rules and pro-c, (October), 1–9.
[3]: Pinson, P., Madsen, H., Nielsen, H. A., Papaefthymiou, G., & Klöckl, B. (2009). From probabilistic forecasts to statistical scenarios of short-term wind power production. Wind Energy, 12(1), 51–62. 
[4]: Golestaneh, F., Gooi, H. B., & Pinson, P. (2016). Generation and evaluation of space–time trajectories of photovoltaic power. Applied Energy, 176, 80–91. 

How to cite: Camal, S., Michiorri, A., and Kariniotakis, G.: Forecast trajectories for the production of a renewable virtual power plant able to provide ancillary services, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19081, https://doi.org/10.5194/egusphere-egu2020-19081, 2020.

EGU2020-3641 | Displays | ERE2.1

Stochastic optimal scheduling of hydropower compensation for wind and photovoltaic power output considering multiple uncertainties

Weifeng Liu, Chao Wang, Xiaohui Lei, Ping-an Zhong, and Qingwen Lu

Multiple uncertainties, including from the uncertainty of a single power (wind power or photovoltaic power) output forecasting to the uncertainty of the combined power output of wind and photovoltaic forecasting to the power shortage after hydropower compensation for wind and photovoltaic power output, exist in the wind-photovoltaic-hydropower system. Furthermore, as the forecast is updated, the above uncertainty will evolve accordingly. Revealing the evolution of multiple uncertainties is of great significance for the hydropower compensation for the combined power output of wind and photovoltaic. We use a generalized martingale model of forecast evolution to describe the uncertainty of a single power output. We then superimpose the single power output to obtain the combined power output of wind and photovoltaic. we establish a stochastic programming with recourse model for optimal scheduling of the hydropower compensation for wind and photovoltaic power output. The results indicate that the uncertainty of the combined power output of wind and photovoltaic forecasting is less than that of wind power output forecasting, and greater than that of photovoltaic power output forecasting. After hydropower compensates for combined power output of wind and photovoltaic, compared with the uncertainty of combined wind and photovoltaic power output forecasting, the uncertainty of power shortage is greatly reduced by 90%, which has significant benefits. And with the dynamic update of the forecast, the uncertainty of the single power output forecast, the uncertainty of the combined power output forecast, and the uncertainty of the power shortage will decrease accordingly.

How to cite: Liu, W., Wang, C., Lei, X., Zhong, P., and Lu, Q.: Stochastic optimal scheduling of hydropower compensation for wind and photovoltaic power output considering multiple uncertainties, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3641, https://doi.org/10.5194/egusphere-egu2020-3641, 2020.

EGU2020-9093 | Displays | ERE2.1

Future wind energy resources in the North Sea as predicted by CMIP6 models

Andrea N. Hahmann, Alfredo Peña, Sara C. Pryor, and Graziela Luzia

Net carbon dioxide emissions have to be brought down to zero in the coming decades to hold the rise in global temperature in this century below the 2°C from pre-industrial levels. This target implies a fundamental transformation of the global energy system that will have to rely heavily on renewable energy sources. Among these, the harvesting of electricity from the wind plays an important role. Yet, climate change itself can impact the supply of renewable energy. Therefore, national climate mitigation plans need to make informed decisions regarding any changes to future extractable wind resources to consider the possible risks.

In this work, we explore the changes in wind climatology over the North Sea in the different shared socioeconomic pathways (SSP) emission scenarios as identified by the output of a selection of CMIP6 simulations. Many northern European countries rely on the wind resources of the North Sea for climate mitigation. As a first step, however, we validate various aspects of the wind speed and direction and their variability in the historical CMIP6 simulations as compared to multiple long-term reanalyses. The work also includes calculations of annual energy production for existing and planned wind farms in the North Sea and how these could change in the coming decades.

How to cite: Hahmann, A. N., Peña, A., Pryor, S. C., and Luzia, G.: Future wind energy resources in the North Sea as predicted by CMIP6 models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9093, https://doi.org/10.5194/egusphere-egu2020-9093, 2020.

EGU2020-7184 | Displays | ERE2.1

Kraken – a scientific and commercial data meta-platform for wind energy resources

Annekatrin Kirsch, Franz Feldtkeller, and Markus Abel

Several international and national initiatives allow access to data from wind measurements, e. g. NREL wind prospector or the international wind atlases. But there is no adequate platform for combined commercial and scientific needs.

Kraken realizes open data concepts for scientific access combined with corresponding licenses for commercial use. To this end, we offer all users to provide links and a possibility for direct upload of wind-related data. Information on data provenance and usability concepts should be provided.

This way, we can collect and provide data of different quality (possibly not to scientific standards) and for different use cases. Scientifically, this may allow access to, e. g., wind park data which would otherwise not be accessible. Commercially, an access to the enormous data bases is possible at one place, a problem that often is underestimated.

On the long run, automatized intelligent analysis of the data will be implemented and the corresponding reports may be published, depending on the licenses related to the underlying data. The whole project is intended to be community-based and extensible to all kind of renewable energy data.

In a first attempt, a website has been launched with limited functionality, now we are trying to involve as many as possible data sources. In addition, we welcome the open implementation of analyses as already offered by other sites (site characterization, feature engineering, improved weather parameterization).

How to cite: Kirsch, A., Feldtkeller, F., and Abel, M.: Kraken – a scientific and commercial data meta-platform for wind energy resources, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7184, https://doi.org/10.5194/egusphere-egu2020-7184, 2020.

EGU2020-21386 | Displays | ERE2.1

Environmental criteria for site selection of wind power projects in South Korea

Jong-Yoon Park and Young-Joon Lee

Wind energy represents the leading source of renewable energy in many developed countries. South Korea has recently introduced large-scale programs to promote the transition from fossil fuels and nuclear power to renewable energy as a source of power. The Korean government has set an energy policy goal to increase the ratio of renewable energy to 20% by 2030. To this end, it is necessary to supply renewable energy facilities with a total capacity of 48.7GW including 30.8GW of photovoltaic power generation and 16.5GW of wind power generation by the target year. Accordingly, we should plan now for the regulation of the location to meet this developing need. However, in South Korea, forests cover 63% of the country's land area so that there is a limit to find a location for the installation of large-scale power generation facilities without occupying forest lands. For example, it is mainly located in forests or farmlands where land costs are relatively low, resulting in a decrease in forest resources and negative impacts on ecosystems and landscapes. Renewable energyexpansion planning should ensure that environmental criteria, of the type outlined in this study, are given appropriate considerations in onshore wind power project site selection. Many of the more problematic wind power sites are best left mountainous forest under the natural conditions, because the environmental or related social impacts are likely to be unacceptably high. Obviously, no plans are likely to be more environmentally desirable in those cases. The alternatives for onshore wind power siting considered the environmental criteria to achieve the goal of wind energy will be suggested.

How to cite: Park, J.-Y. and Lee, Y.-J.: Environmental criteria for site selection of wind power projects in South Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21386, https://doi.org/10.5194/egusphere-egu2020-21386, 2020.

EGU2020-14253 | Displays | ERE2.1

IEA Wind Task 36 Forecasting

Gregor Giebel, Will Shaw, Helmut Frank, Pierre Pinson, Caroline Draxl, John Zack, Corinna Möhrlen, Georges Kariniotakis, and Ricardo Bessa

Wind power forecasts have been used operatively for over 20 years. Despite this fact, there are still several possibilities to improve the forecasts, both from the weather prediction side and from the usage of the forecasts. The International Energy Agency (IEA) Wind Task on Wind Power Forecasting organises international collaboration, among national weather centres with an interest and/or large projects on wind forecast improvements (NOAA, DWD, UK MetOffice, ...), forecast vendors and forecast users.
Collaboration is open to IEA Wind member states, 12 countries are already therein.

The Task is divided in three work packages: Firstly, a collaboration on the improvement of the scientific basis for the wind predictions themselves. This includes numerical weather prediction model physics, but also widely distributed information on accessible datasets. Secondly, we will be aiming at an international pre-standard (an IEA Recommended Practice) on benchmarking and comparing wind power forecasts, including probabilistic forecasts. This WP will also organise benchmarks for NWP models. Thirdly, we will be engaging end users aiming at dissemination of the best practice in the usage of wind power predictions.

The main result is the IEA Recommended Practice for Selecting Renewable Power Forecasting Solutions. This document in three parts (Forecast solution selection process, and Designing and executing forecasting benchmarks and trials, and their Evaluation) takes its outset from the recurrent problem at forecast user companies of how to choose a forecast vendor. The first report describes how to tackle the general situation, while the second report specifically describes how to set up a forecasting trial so that the result is what the client intended. Many of the pitfalls which we have seen over the years, are avoided.

Other results include a paper on possible uses of uncertainty forecasts, an assessment of the uncertainty chain within the forecasts, and meteorological data on an information portal for wind power forecasting. This meteorological data is used for a benchmark exercise, to be announced at the conference. The poster will present the latest developments from the Task, and announce the next activities.

How to cite: Giebel, G., Shaw, W., Frank, H., Pinson, P., Draxl, C., Zack, J., Möhrlen, C., Kariniotakis, G., and Bessa, R.: IEA Wind Task 36 Forecasting, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14253, https://doi.org/10.5194/egusphere-egu2020-14253, 2020.

EGU2020-20205 | Displays | ERE2.1

Smart4RES: Towards next generation forecasting tools of renewable energy production

George Kariniotakis, Simon Camal, Ricardo Bessa, Pierre Pinson, Gregor Giebel, Quentin Libois, Raphaël Legrand, Matthias Lange, Stefan Wilbert, Bijan Nouri, Alexandre Neto, Remco Verzijlbergh, Ganesh Sauba, George Sideratos, Efrosyni Korka, and Stephanie Petit

The aim of this paper is to present the objectives, research directions and first highlight results of the Smart4RES project, which was launched in November 2019, under the Horizon 2020 Framework Programme. Smart4RES is a research project that aims to bring substantial performance improvements to the whole model and value chain in renewable energy (RES) forecasting, with particular emphasis placed on optimizing synergies with storage and to support power system operation and participation in electricity markets. For that, it concentrates on a number of disruptive proposals to support ambitious objectives for the future of renewable energy forecasting. This is thought of in a context with steady increase in the quantity of data being collected and computational capabilities. And, this comes in combination with recent advances in data science and approaches to meteorological forecasting. Smart4RES concentrates on novel developments towards very high-resolution and dedicated weather forecasting solutions. It makes optimal use of varied and distributed sources of data e.g. remote sensing (sky imagers, satellites, etc), power and meteorological measurements, as well as high-resolution weather forecasts, to yield high-quality and seamless approaches to renewable energy forecasting. The project accommodates the fact that all these sources of data are distributed geographically and in terms of ownership, with current restrictions preventing sharing. Novel alternative approaches are to be developed and evaluated to reach optimal forecast accuracy in that context, including distributed and privacy-preserving learning and forecasting methods, as well as the advent of platform-enabled data-markets, with associated pricing strategies. Smart4RES places a strong emphasis on maximizing the value from the use of forecasts in applications through advanced decision making and optimization approaches. This also goes through approaches to streamline the definition of new forecasting products balancing the complexity of forecast information and the need of forecast users. Focus is on developing models for applications involving storage, the provision of ancillary services, as well as market participation.

How to cite: Kariniotakis, G., Camal, S., Bessa, R., Pinson, P., Giebel, G., Libois, Q., Legrand, R., Lange, M., Wilbert, S., Nouri, B., Neto, A., Verzijlbergh, R., Sauba, G., Sideratos, G., Korka, E., and Petit, S.: Smart4RES: Towards next generation forecasting tools of renewable energy production, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20205, https://doi.org/10.5194/egusphere-egu2020-20205, 2020.

EGU2020-12262 | Displays | ERE2.1

State of the art of Seasonal and Subseasonal Wind and Wind Power Forecasting for the Iberian Peninsula and the Canary islands

Juan A. Añel, Susana Bayo-Besteiro, Michael García-Rodríguez, and Xavier Labandeira

Renewable energy plays a key role to play in the transition towards a low-carbon society and many countries have been investing in R&D and deployment of renewables over the last few decades. Despite its importance, relatively little attention has been focused on the crucial impact of weather and climate on energy demand and supply, or on the seasonal forecast generation or operational planning of renewable technologies. In particular, to improve the operation and longer-term planning of renewables it is essential to consider seasonal and subseasonal weather forecasting. Unfortunately, reports that focus on these issues are not common in the scientific literature.
Here we present a systematic review of the seasonal forecasting of wind and wind power for the Iberian peninsula and the Canary Islands, a region leading the world in the development of renewable energies (particularly wind), and thus an important illustration in global terms. To this end, we consider the scientific literature published over the last eleven years (2008-2018). An initial search of this literature produced 8355 documents, but our review suggests that only around 0.3% are actually relevant to our purposes. The results show that the teleconnection patterns (NAO, EA, and SCAND) and the stratosphere are important sources of predictability in the Iberian Peninsula and that GloSea5 is an effective model for seasonal wind forecasting for the region. We conclude that the existing literature in this crucial area is very limited, which points to the need for increased research efforts. Moreover, the approach and methods developed here could be applied to other areas for which systematic reviews might be either useful or necessary.

How to cite: Añel, J. A., Bayo-Besteiro, S., García-Rodríguez, M., and Labandeira, X.: State of the art of Seasonal and Subseasonal Wind and Wind Power Forecasting for the Iberian Peninsula and the Canary islands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12262, https://doi.org/10.5194/egusphere-egu2020-12262, 2020.

EGU2020-12818 | Displays | ERE2.1

Probabilistic and Point Solar Forecasting Using Attention Based Dilated Convolutional Neural Network

Moumita Saha, Bhalchandra Naik, and Claire Monteleoni

Climate change is evident at present with threatening effects as intense hurricanes, rising sea level, increase number of droughts, and shifting weather patterns. Burning of fossil fuels and anthropogenic activities increase the greenhouse gases concentration in atmosphere, which is a major cause behind the climate change. Renewable energy as solar is a good source for combating the causes of climate change by producing clean energy.  

The efficient integration of solar energy into electrical grids requires an accurate prediction of solar irradiance. The solar irradiance is the flux of radiant energy received per unit area of the earth from the sun. Existing techniques use basic stochastic (such Gaussian model, hidden Markov model, etc.) and ensemble neural network models for solar forecasting. However, recent literature reflects the potential of deep-learning models over the statistical model.

In this paper, we propose a deep-learning-based one-dimensional, multi-quantile convolution neural network for predicting the solar irradiance. The network employs dilation in its convolution kernel, which helps capturing the long-term dependencies between instances of the input climatic variables. Additionally, we also incorporate the attention mechanism between the input and learned representation from the convolution, which allows attending to the temporal instance of features for improved prediction. We perform both short-term (three hours ahead) and long-term (twenty-four hours ahead) solar irradiance prediction. We exhaustively present the forecast for all four seasons (spring, summer, fall, and winter) as well as for the whole year. We provide a point solar forecast along with forecast at different quantiles. Quantile forecast provides a range of estimates with varying confidence intervals, which allows better interpretation as compared to point forecast. This notion of confidence associated with each quantile makes the forecasting probabilistic.

In order to validate our approach, we consider two cities (Boulder and Fort Peck) from the SURFAD network and examine twenty climatic features as input to our model.  Additionally, we learned embedded reduced input dimension using an autoencoder. The proposed architecture is trained with all the input features and reduced features, independently. We observe the prediction error for Boulder is higher than Fort Peck, which can be due to the volatile weather of Boulder. The proposed model forecasts the solar irradiance for winter with a higher accuracy as compared to spring, summer, or fall. We observe the correlation coefficients as 0.90 (Boulder) and 0.92 (Fort Peck) between the actual and predicted solar irradiance.  The long-term forecast shows average improvements of 37.1% and 33.1% in root mean square error (RMSE) over existing numerical weather prediction model for Boulder and Fort Peck, respectively. Similarly, the short-term forecast shows improvements of 33.7% and 34.2% for the respective cities.

How to cite: Saha, M., Naik, B., and Monteleoni, C.: Probabilistic and Point Solar Forecasting Using Attention Based Dilated Convolutional Neural Network, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12818, https://doi.org/10.5194/egusphere-egu2020-12818, 2020.

EGU2020-16810 | Displays | ERE2.1

Statistical Post-Processing with Standardized Anomalies and Variable Selection for Wind Farm Forecasts

Markus Dabernig, Alexander Kann, and Irene Schicker

Numerical weather predictions are often too coarse to represent single turbines in a wind park and post-processing of the individual turbines is necessary. However, individual post-processing can lead to inconsistencies in forecasts for a wind farm. Using standardized anomalies allows to forecast all turbines simultaneously. Therefore, a climatological mean is subtracted from observations/predictions and then divided by a climatological spread which eliminates any site-specific characteristics.

Additionally, different sources of input can be used, such as variables from a global model, a mesoscale model or observations to improve forecasts. However, to prevent overfitting a variable selection method is needed to determine the most important predictors. The combination of standardized anomalies and a variable selection method provides a convenient method for good forecasts of wind farms.

How to cite: Dabernig, M., Kann, A., and Schicker, I.: Statistical Post-Processing with Standardized Anomalies and Variable Selection for Wind Farm Forecasts , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16810, https://doi.org/10.5194/egusphere-egu2020-16810, 2020.

EGU2020-3034 | Displays | ERE2.1

A simple gust estimation algorithm and machine learning based nowcasting for wind turbines

Irene Schicker and Petrina Papazek

Wind gusts and high wind speeds need to be considered in wind power industry and power grid management as they affect construction, material, siting and maintenance of turbines and power lines. Furthermore, gusts are an important information source on turbulence conditions in the atmosphere at the respective sites.
Often, the wind farm operators only provide basic data of the turbines such as average wind speed, direction, power and temperature. However, they require forecasts of gusts, too. Thus, a simple gust estimation algorithm based on the average wind speed was developed. The algorithm is tested at different mast measurement sites and WFIP2 data and applied to selected wind turbines. Results show that the algorithm is skillful enough to be used as a first guess gust estimation for single turbines and is, thus, used for nowcasting.
For nowcasting for the first two hours with a temporal fequency of ten minutes solely observations are used. A high-frequency wind speed and gust nowcasting ensemble based on different machine learning methodologies, including an ensemble for every method, was developd. Used are boosting, random forest, linear regression, a simple monte carlo method and a feed forward neural network. Results show that perturbing the observations provides a good forecasting spread for at least some of the methods. However, for other methods the spread is reduced significantly. Most of the used methods are able to provide good forecastst. However, hyperparameter tuning for the lightGBM boosting algorithm and the neural network is still needed.

How to cite: Schicker, I. and Papazek, P.: A simple gust estimation algorithm and machine learning based nowcasting for wind turbines, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3034, https://doi.org/10.5194/egusphere-egu2020-3034, 2020.

EGU2020-7178 | Displays | ERE2.1

Mesoscale resolving high-resolution simulation of wind farms in COSMO-CLM 5

Naveed Akhtar and Burkhardt Rockel

The rapid development of offshore wind farms has raised concerns about the local environment and ecosystem. Wind farms influence the local meteorology by extracting kinetic energy from the wind field and by generating a large wake. The North Sea is one of the main regions of the world where the growth of offshore wind farms is rapidly increasing. In this study, we analyze the impact of large-scale offshore wind farms in the North Sea on local meteorology using regional climate model COSMO-CLM. For this purpose, the parametrization for wind turbine driven by Fitch et al. (2012) and Blahak et al. (2010), previously implemented in COSMO-CLM v 4.8 at KU-Leuven (Chatterjee et al. 2016), has been implemented in the latest version 5 of COSMO-CLM. Here we present the first results of COSMO-CLM long-term simulations with and without wind farms using mesoscale resolving high-resolution horizontal atmospheric grid spacing (~ 2 km).

How to cite: Akhtar, N. and Rockel, B.: Mesoscale resolving high-resolution simulation of wind farms in COSMO-CLM 5, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7178, https://doi.org/10.5194/egusphere-egu2020-7178, 2020.

The purpose of this study is to develop an ensemble-based data assimilation method to accurately predict wind speed in wind farm and provide it for the use of wind energy intelligent forecasting platform. As Taiwan government aimed to increase the share of renewable energy generation to 20% by 2025, among them, the uncertain wind energy output will cause electricity company has to reserve a considerable reserve capacity when dispatching power, and it is usually high cost natural gas power generation. In view of this, we will develop wind energy intelligent forecasting platform with an error of 10% within 72 hours and expect to save hundred millions of dollars of unnecessary natural gas generators investment. Once the wind energy can be predicted more accurately, the electricity company can fully utilize the robustness and economy of smart grid supply. Therefore, the mastery of the change of wind speed is one of the key factors that can reduce the minimum error of wind energy intelligent forecasting.

There are many uncertainties in the numerical meteorological models, including errors in the initial conditions or defects in the model, which may affect the accuracy of the prediction. Since the deterministic prediction cannot fully grasp the uncertainty in the prediction process, so it is difficult to obtain all possible wind field changes. The development of ensemble-based data assimilation prediction is to make up for the weakness of deterministic prediction. With the prediction of 20 wind fields as ensemble members, it is expected to include the uncertainty of prediction, quantify the uncertainty, and integrate the wind speed observations of wind farms as well to provide the optimal prediction of wind speed for the next 72 hours. The results show that the prediction error of wind speed within 72 hours is 6% under different weather conditions (excluding typhoons), which proves that the accuracy of wind speed prediction by combining data assimilation technology and ensemble approach is better.

How to cite: Fan, Y.-M.: Ensemble-Based Data Assimilation for Wind Forecasting – Application to Wind Farm, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18144, https://doi.org/10.5194/egusphere-egu2020-18144, 2020.

The operation cost for wind parks make up a major fraction of the park’s overall lifetime cost. To facilitate an optimal wind park operation and maintenance, we present a decision support system that automatically scans the stream of telemetry sensor data generated from the turbines. By learning decision boundaries and normal reference operating states using machine learning algorithms, the decision support system can detect anomalous operating behaviour in individual wind turbines and diagnose the involved turbine sub-systems. Operating personal can be alerted if a normal operating state boundary is exceeded. We demonstrate the successful detection and diagnosis of anomalous power production for a case study of a German onshore wind park for turbines of 3 MW rated power.

How to cite: Meyer, A.: Machine-learning based wind turbine operating state detection and diagnosis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6532, https://doi.org/10.5194/egusphere-egu2020-6532, 2020.

With the rapid development of social economy, China's energy demand has been growing at an alarming rate. The annual cumulative power generation is about  6.8 trillion kilowatts hour in 2017, and 70% of them is provided by fossil fuel resources, so it is important to promote the use of renewable and clean energy, such as solar power generation technology. The advantages of using solar panel roof in urban areas include reduction of the need of land use in the crowed city and less dependence on fossil fuels. However, there is need to understand impacts of solar roof on local climate, on energy supply during heatwaves, and associated economic benefits in China. This study selected a heatwave event in Jiangsu province, China to simulate the impact of solar panel roof on local thermal environment and energy supply. During that time, the cooling energy consumption reached more than half of the total electricity consumption. A new heat transfer scheme of solar panel roof was introduced into WRF/BEP/BEM model, which include layers (glass protective panel, solar panel, bottom plate) and was divided into two types for heat transfer calculation: bracket and non-bracket. The results showed that the urban average 2-m daytime temperature decreased by 0.3℃ in non-bracket case which is better than that of bracket case, while its cooling effect on nighttime temperature was small. For the bracket case, its cooling effect on daytime and nighttime air temperature were equal (0.2oC). Both solar panel roofs can reduce indoor daytime air temperature with the maximum cooling effect around 11:00 local time for non-bracket roof and 14:00 for bracket roof. However, bracket roof increased nighttime indoor air temperature and air-conditioning energy consumption. Solar panel roofs also reduce daytime turbulent kinetic energy and constrain the development of boundary layer. Results also show that with solar photoelectric conversion efficiency being 0.14, the photovoltaic power generation can meet 84.1%, 61.3% and 35.9% of the cooling energy consumption for high-density, low-density residential areas and commercial areas, respectively, during this heatwave event.

How to cite: Wang, Y., Chen, F., Hao, X., and Wang, F.: The influence of solar panel roof on urban thermal environment and cooling energy demand during a heat wave event in 2017, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1437, https://doi.org/10.5194/egusphere-egu2020-1437, 2020.

EGU2020-13349 | Displays | ERE2.1

The Potential Impact of Solar Photovoltaic Installation on Local Circulation and Convection in Taipei

Po-Shen Chang, Jen-Ping Chen, and Cheng-I Hsieh

This study investigates the potential impact of rooftop solar photovoltaic (PV) installation on local convection in urban area. Rooftop solar PV system is a space-efficient option to deploy renewable energies in the crowded urban area. However, as the installation scale increases, unintentional impact on local climate may emerge. In particular, PV array deployment can change the surface radiative balance and thus enhance or reduce the urban heat island effect. The urban heat island effect has been hypothesized to influence afternoon thunderstorm activity in the tropical island, Taiwan. Therefore, temperature change due to PV installation may also alter the local circulation and convection. This research takes the Taipei City, which is a metropolitan area in northern Taiwan, for a case study. Citywide rooftop solar PV installation experiments are conducted by using the Weather Research and Forecasting (WRF) Model coupled with urban canopy model. Different PV conversion efficiency scenarios, including currently and future technology levels, are simulated to evaluate the potential impact on local circulation and convection.

How to cite: Chang, P.-S., Chen, J.-P., and Hsieh, C.-I.: The Potential Impact of Solar Photovoltaic Installation on Local Circulation and Convection in Taipei, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13349, https://doi.org/10.5194/egusphere-egu2020-13349, 2020.

The Weather Research and Forecasting (WRF) model fitted with the Fitch et al. (2012) scheme for parameterization of the effect of wind energy extraction is used to study the effects of very large wind farms on regional weather. Two real data cases have been run in a high spatial resolution (grid size 500 m). Both cases are characterized by a convective westerly flow. The inner model domain covers the North Sea and Denmark. The largest windfarm consists of 200.000 wind turbines each with a capacity of 8MW. The model is run for up to 12 hours with and without the wind farm. The impact on the regional weather of these very large wind farms are studied and presented. Furthermore, the effect of horizontal spacing between wind turbines is investigated. Significant impact on the regional weather from the very large wind farms was found. Horizontal wind speed changes occur up to 3500m above the surface. The precipitation pattern is greatly affected by the very large wind farms due to the enhanced mixing in the boundary layer. Increased precipitation occurs at the front? within the wind farm, thus leaving the airmass relatively dry downstream when it reaches the Danish coast, resulting in a decrease in precipitation here compared to the control run. The formation of a small low level jet is found above the very large wind farm. Furthermore, wake effects from individual wind turbines decrease the total power production. The wind speed in the real data cases are well above the speed of maximum power production of the wind turbines. Yet most of the 200.000 wind turbines are producing only 1MW due the wake effects. A simulation run with a wind farm of 50.000 8MW wind turbines was also run. This windfarm covers the same area as the previous one, but horizontal distance between wind turbines are 1000m instead of 500m. This configuration was found to produce a similar amount of power as the 200.000 configuration. However, the atmospheric impact on regional weather is smaller but still large with 50.000 wind turbines.

How to cite: Jacobsen, S. and Walløe Hansen, A.: A study of the impact of very large wind farms on regional weather using the WRF model in high resolution, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16884, https://doi.org/10.5194/egusphere-egu2020-16884, 2020.

Storm Xaver impacted the northern Europe on 5-6 December 2013.  It developed southeast of Greenland and passed north of Scotland and across southern Norway on a trajectory that led to a cold air outbreak across the North Sea and intense convection activity in northern Europe.  Strong sustained north winds led to a high storm surge that impacted all countries bordering the North Sea.  Storm Xaver was a century scale event with certain locations around the North Sea reporting their highest ever water levels since the start of modern records.  Media reports from the time of the storm chronicle the scale of the disruptions, including many cancelled flights, interrupted rail networks, closed bridges and roads, coastal building collapses, and power blackouts across northern Europe.  Much of this was due to the strong winds, but coastal storm surge flooding was important in the UK, and it led to interrupted port operations around the North Sea.

The storm was important for energy infrastructure and particularly for wind energy infrastructure.  In the northern North Sea, petroleum platforms were evacuated and operations closed ahead of the storm as a precautionary measure.  A number of onshore wind turbines were badly damaged by high winds and lightning strikes in the UK and Germany.  Over the North Sea, wind speeds exceeded the turbine shutdown threshold of 25 m/s for an extended period of time, with economic impacts from the loss of power generation.   In the German Bight, the FINO1 offshore wind energy research platform was damaged at the 15 m level by large waves.  This was the third report of storm damage to this platform after Storm Britta in 2006 and Storm Tilo in 2007.  Researchers have highlighted the need to reassess  the design criteria for offshore wind turbines based on these kinds of extreme meteorological events.  For the offshore wind industry, an important element of energy meteorology is to characterize both the evolving wind and wave fields during severe storms as both elements contribute to turbine loads and potential damage.

The present conference contribution presents a literature review of the major events during Storm Xaver and impacts on energy infrastructure.  Tide gauge records are reanalyzed to trace the progress of the storm surge wave around the North Sea.  A spectral analysis is used to separate the long period storm surge component, diurnal/semidiurnal tide, and short period components in the original water level record.  The short period component of the tide gauge record is important as it may be linked with infragravity waves that have been implicated in certain cases of offshore infrastructure damage in addition to coastal erosion.  Discussion is made of offshore wave records during the storm.  Storm Xaver is compared with two damaging offshore storms in 2006 and 2007.

How to cite: Kettle, A.: Storm Xaver over Europe in December 2013 and its energy meteorological impacts, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6029, https://doi.org/10.5194/egusphere-egu2020-6029, 2020.

EGU2020-13916 | Displays | ERE2.1

Quality of wind characteristics in recent wind atlases over the North Sea

Peter C. Kalverla, Albert A. M. Holtslag, Reinder J. Ronda, and Gert-Jan Steeneveld

Many wind energy applications rely on engineering models that simulate the interaction between the wind and the turbine(s). These models often represent the wind in an idealised fashion, which introduces uncertainties that translate into financial risk for investors.

Over the past four years, we investigated these uncertainties by re-evaluating common assumptions about the (offshore) wind field, studying the physics that govern winds in coastal areas, evaluating the representation of offshore winds in weather models, and proposing alternative methods to represent the offshore wind climate in engineering models.

Uncertainties in the wind climate were studied through a number of ‘anomalous wind events’. An important and illustrative example is the low-level jet, which can substantially impact power production and wind loads on the turbine. We found that low-level jets occur often over the North Sea. Moreover, numerical weather prediction models struggle to adequately represent this phenomenon. A climatology based only on observations is also biased, because the observations are limited in time and space. Thus, we combined field observations with output of reanalysis products to obtain a reliable climatology.

At the 2020 general assembly, we will present a new evaluation of three recent wind atlases over the North Sea: ERA5, The New European Wind Atlas (NEWA), and the Dutch Offshore Wind Atals (DOWA). With virtually no bias, DOWA outperforms the other datasets in terms of the mean wind profile and also in the representation of wind shear. The high resolution offered by DOWA (2.5 km) and NEWA (3 km) leads to substantial improvements in the frequency and the level of detail with which low-level jets are captured. However, the timing of the events is a bit off in NEWA. By contrast, DOWA was produced using continuous three-hourly data-assimilation updates, which imposes a much stronger constraint on the simulations. Consequently, the timing of low-level jets in DOWA is much better represented. This makes for a low-level jet climatology with unprecedented accuracy and detail, facilitating resource assessment and future studies on the characteristics of the offshore wind climate.

How to cite: Kalverla, P. C., Holtslag, A. A. M., Ronda, R. J., and Steeneveld, G.-J.: Quality of wind characteristics in recent wind atlases over the North Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13916, https://doi.org/10.5194/egusphere-egu2020-13916, 2020.

A large-eddy simulation (LES) model, coupled with a dynamic actuator-disk model, is used to investigate the turbine power production and the turbine wake distribution in large wind farms where the streamwise turbine spacing of 7, 9, 12, 15, and 18 rotor diameters are considered. Two incoming flow conditions, three wind turbine arrangements, as well as the five turbine spacings are involved in this study, which leads to a total of 30 LES wind farm scenarios. The two incoming flow conditions have the same mean velocity of 9 m s-1 but different turbulence intensity levels (i.e., 7% and 11%) at the hub height level. The considered turbine arrangements are the perfectly-aligned, laterally-staggered, and vertically-staggered layouts. The simulated results show that the turbine power production has a significant improvement by increasing the streamwise turbine spacing. With increasing the streamwise turbine spacing from 7 to 18 rotor diameters, the overall averaged power outputs are raised by about 27% in the staggered wind farms and about 38% in the aligned wind farms. The wind farm scenarios with the turbine spacing of 12d or greater in a large wind farm can lead to an increasing trend in the power production from the downstream turbines in the high-turbulence inflow condition, or also avoids the degradation of the power output on the turbines with the low-turbulence inflow condition. The flow adjustment above the wind farm results in the generation of the internal boundary layer (IBL), which grows up vertically along with the wake-wise direction. The growth of the IBL is found to be affected by the changes in the inflow condition and the turbine spacing. The IBL depth above the wind farms is found to be influenced by the turbine spacing, whereas the IBL depth in the downstream wake region of the wind farms shows a rapid increase under the high-turbulence inflow condition.

How to cite: Wu, Y.-T. and Tsao, Y.-H.: Power Output Efficiency in Large Wind Farms with Different Streamwise Turbine Spacing, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4484, https://doi.org/10.5194/egusphere-egu2020-4484, 2020.

EGU2020-18585 | Displays | ERE2.1

Satellite based estimation of atmospheric wakes downstream offhore windparks using a new objective filter technique

Johannes Schulz-Stellenfleth, Bughsin Djath, and Verena Haid

The large number of already existing and planned offshore wind parks in the German Bight leads to challenging requirements with regard to reliable information on various processes in the atmosphere and the ocean. In particular wind shadowing effects play a major role for the optimal planning and operation of wind park installations. Synthetic Aperture Radar (SAR) satellites have proved their capability of giving a 2D view of the wakes generated behind wind farms at a  high spatial resolution. However, the estimation of wind speed deficits from SAR data is still a challenge, because undisturbed reference wind fields are usually not available at the exact location of the wake. A common approach is therefore to identify some reference areas on SAR scenes outside the wake region, which naturally leads to errors in the deficit computations. 
In this study a new filter approach for the deficit estimation is proposed, which allows to derive error bars for the deficits. The filter is based on a 2D convolution operation with a filter kernel, which has a shape depending on the wind park geometry and the wind direction. The errors depend on spectral properties of the background wind fields, which are estimated from SAR data as well. In this context the stability of the atmospheric boundary layer is shown to play a major role. Examples are shown using data acquired by the SENTINEL-1A/B satellites. The approach is seen as a contribution to make SAR based deficit computations more objective and automised, which is essential for the application of the method to larger data sets and to make wake analysis done in different regions more comparable.

How to cite: Schulz-Stellenfleth, J., Djath, B., and Haid, V.: Satellite based estimation of atmospheric wakes downstream offhore windparks using a new objective filter technique , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18585, https://doi.org/10.5194/egusphere-egu2020-18585, 2020.

EGU2020-12654 | Displays | ERE2.1

Layout optimization for a large offshore wind farm using Genetic Algorithm

K Narender Reddy and S Baidya Roy

Wind Farm Layout Optimization Problem (WFLOP) is an important issue to be addressed when installing a large wind farm. Many studies have focused on the WFLOP but only for a limited number of turbines (10 – 100 turbines) and idealized wind speed distributions. In this study, we apply the Genetic Algorithm (GA) to solve the WFLOP for large wind farms using real wind data.

The study site is the Palk Strait located between India and Sri Lanka. This site is considered to be one of the two potential hotspots of offshore wind in India. An interesting feature of the site is that the winds here are dominated by two major monsoons: southwesterly summer monsoon (June-September) and northeasterly winter monsoon (November to January). As a consequence, the wind directions do not drastically change, unlike other sites which can have winds distributed over 360o. This allowed us to design a wind farm with a 5D X 3D spacing, where 5D is in the dominant wind direction and 3D is in the transverse direction (D- rotor diameter of the turbine - 150 m in this study).

Jensen wake model is used to calculate the wake losses. The optimization of the layout using GA involves building a population of layouts at each generation. This population consists of, the best layouts of the previous generation, crossovers or offspring from the best layouts of the previous generation and few mutated layouts. The best layout at each generation is assessed using the fitness or objective functions that consist of annual power production by the layout, cost incurred by layout per unit power produced, and the efficiency of the layout. GA mimics the natural selection process observed in nature, which can be summarised as survival of the fittest. At each generation, the layouts performing the best would enter the next generation where a new population is created from the best performing layouts.

GA is used to produce 3 different optimal layouts as described below. Results show that:

A ~5GW layout – has 738 turbines, producing 2.37 GW of power at an efficiency of 0.79

Layout along the coast – has 1091 turbines, producing 3.665 GW of power at an efficiency of 0.82.

Layout for the total area – has 2612 turbines, producing 7.82 GW of power at an efficiency of 0.74.

Thus, placing the turbines along the coast is more efficient as it makes the maximum use of the available wind energy and it would be cost-effective as well by placing the turbines closer to the shores.

Wind energy is growing at an unprecedented rate in India. Easily accessible terrestrial resources are almost saturated and offshore is the new frontier. This study can play an important role in the offshore expansion of renewables in India.

How to cite: Reddy, K. N. and Roy, S. B.: Layout optimization for a large offshore wind farm using Genetic Algorithm, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12654, https://doi.org/10.5194/egusphere-egu2020-12654, 2020.

EGU2020-14412 | Displays | ERE2.1

Climatological Analysis of the Potential of Solar and Wind Energy in Germany

Jaqueline Drücke, Michael Borsche, Paul James, Frank Kaspar, Uwe Pfeifroth, Bodo Ahrens, and Jörg Trentmann

Renewable energies, like solar and wind energy, play an important role in current and future energy supply in Germany and Europe. The renewable energy production highly depends on weather, which leads to an increasing impact of the meteorological fluctuations on energy production.

Here, climatological datasets with high spatial and temporal resolution are used to simulate the electrical energy production from photovoltaic (PV) installations and wind turbines. For the solar radiation the CM SAF SARAH 2.1 dataset is used, which includes global and direct radiation with a temporal resolution of 30 minutes and a grid spacing of 0.05°. The data is available from 1983 to 2017. The regional reanalysis COSMO-REA6 provides hourly wind speed data from 1995 to 2015 with a spatial resolution of 6km. Based on these datasets capacity factors are calculated for PV and wind energy for Germany. Using the spatial distribution of solar panels and wind turbines as well as electrical power generation data from 2015 the simulated capacity factors were converted into (potential) hourly power generation in Germany from 1995 to 2015. 

The main aim of this study is to identify weather regimes where renewable energy production from solar and wind was comparable low. Due to high power production from solar radiation, which exhibits a comparable low variability and high predictability, in summer, all low production events occur in winter. During winter, wind power is the main contributor to renewable energy production. On the basis of the hourly time series of simulated power production the weather regimes that are associated with multiple days of low renewable energy production are identified and analysed. European regions are identified that exhibit comparably high potential renewable power production for those weather regimes with low energy production in Germany.  

How to cite: Drücke, J., Borsche, M., James, P., Kaspar, F., Pfeifroth, U., Ahrens, B., and Trentmann, J.: Climatological Analysis of the Potential of Solar and Wind Energy in Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14412, https://doi.org/10.5194/egusphere-egu2020-14412, 2020.

EGU2020-18130 | Displays | ERE2.1

Wind energy potential assessment in western Mediterranean

Platon Patlakas, Christos Stathopoulos, Ariadni Gavriil, George Galanis, and George Kallos

Wind energy investments have met a quick growth during the last decades due to the stricter climate policies, the need for energy independence and the higher profits coming from the smaller costs of such applications. Moreover the evolution of technology leads to the characterization of more areas as suitable for energy applications. Offshore wind farms are a nice example of how to build bigger, more efficient and resistant in extreme conditions wind power plants.

The present work is focused on the determination of the suitability of an offshore marine area for the development of wind farm structures. More specifically the region of interest is the marine area on the south of France including the Gulf of Leon. For the needs of the study a 10-year database, produced employing state of the art atmospheric and wave models, is utilized. The wind and wave parameters used, have a spatial resolution of 6 km and a frequency of one hour.

Wind speed and power probability distribution characteristics are discussed in different heights throughout the domain. Particular locations are selected for a more comprehensive analysis. At the same time extreme wind and wave conditions and their 50-years return period are analyzed and used to define the safety level of the wind farms structural characteristics. The outcome could lead to a review of the area suitability for wind farm development, providing a new tool for technical/research teams and decision makers.

How to cite: Patlakas, P., Stathopoulos, C., Gavriil, A., Galanis, G., and Kallos, G.: Wind energy potential assessment in western Mediterranean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18130, https://doi.org/10.5194/egusphere-egu2020-18130, 2020.

EGU2020-19833 | Displays | ERE2.1

Drivers of Extreme Wind Events in Mexico for Wind Power Applications

Simon Thomas, Oscar Martinez-Alvarado, Dan Drew, and Hannah Bloomfield

In this talk, we investigate the causes of the strongest and weakest winds observed across Mexico and explore the consequences of these to current and future wind energy production in the country. Using 40 years of the ERA-5 atmospheric reanalysis data, we find that the strongest winds in this region are caused by cold surges, where an anticyclone moves South from the Central United States of America resulting in strong Northerly winds across the Gulf of Mexico which channel through the gap in the mountains to the South of Mexico. Other regions have different drivers for high and low wind speed events. The strongest winds across the East coast of Mexico originate from Easterly trade winds propagating across the Gulf of Mexico, whereas those in Baja California Sur are influenced by the proximity of the North Pacific High. These regions in Mexico have peak (and sustained low) wind speeds at different times of year which suggests that wind farms in different regions could compliment one another to optimise wind power generation. However, all stations but Baja California Sur see the same weather patterns associated with weak wind events, meaning that low wind power production may be unavoidable at these times. The conditions that proceed these sustained periods of strong and weak winds are explored to gain some predictability for wind power applications. The El Nino Southern Oscillation is found to influence wind speeds at some locations across Mexico at sub-seasonal time-scales.

How to cite: Thomas, S., Martinez-Alvarado, O., Drew, D., and Bloomfield, H.: Drivers of Extreme Wind Events in Mexico for Wind Power Applications, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19833, https://doi.org/10.5194/egusphere-egu2020-19833, 2020.

EGU2020-21897 | Displays | ERE2.1

Wind conditions over the Baltic Sea – comparing reanalysis data sets with observations

Christoffer Hallgren, Erik Sahlée, Stefan Ivanell, Heiner Körnich, and Ville Vakkari

The potential of increasing the amount of offshore wind energy production in the Baltic Sea has been of great interest for many countries and wind power companies for a long time. From a meteorological point of view, there are several special wind characteristics that are observed in this area that needs to be taken into consideration when planning for a wind farm. For example, as the Baltic Sea is a semi-enclosed basin surrounded by coastlines in all directions, phenomenon such as low-level jets occur frequently.

In order to create a climatology of the wind conditions over the Baltic Sea, with wind power applications in mind, four different state-of-the-art reanalysis data sets (MERRA2, ERA5, UERRA and NEWA) have been compared with measurements from LIDAR systems and high meteorological towers (Anholt, Finnish Utö, FINO2 and Östergarnsholm). The performance of the data sets has been analyzed in terms of stability and governing synoptic weather conditions as well as seasonal and diurnal variations. By selecting the most suitable reanalysis data set and using the observations to make corrections, a climatology for wind conditions over the Baltic Sea, focusing on the low-level jets, has then been constructed.

How to cite: Hallgren, C., Sahlée, E., Ivanell, S., Körnich, H., and Vakkari, V.: Wind conditions over the Baltic Sea – comparing reanalysis data sets with observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21897, https://doi.org/10.5194/egusphere-egu2020-21897, 2020.

EGU2020-6426 | Displays | ERE2.1

Synthetic Wind Generation Records for Australian Wind Farms

Evgenia Titova and Rashmi Mittal

In this study, we present methodology to create synthetic multi-year wind generation dataset at minute-scale granularity at the existing and future Australian wind farms. The purpose of the dataset  is to assist studies of penetration of large scale and distributed renewable generation into the electricity systems and its impact on power system security in the National Energy Market (NEM).

Synthetic historical records are based on a spatial and temporal blend of reanalysis datasets with the minute-scale wind speeds observations at Bureau of Meteorology weather station network. Strengths and weaknesses of reanalysis data are illustrated and a correction methodology discussed. A method to introduce minute-scale and sub-hourly fluctuations absent in the reanalyses records is presented. Expected statistical properties of sub-hourly fluctuations in the wind generation records are derived from the characteristics of the background atmospheric state in the vicinity of the wind farms.

The accuracy of the dataset is validated in terms of  power spectra and ramping frequencies in the simulated timeseries against existing minute-scale observations of wind generation at Australian Wind farms. The statistical properties of the observed and simulated timeseries match reasonably well, overall making the dataset suitable for the investigations of  the implications of wind ramping on energy demand and generation at the existing and foreseeable infrastructure build in the NEM.

How to cite: Titova, E. and Mittal, R.: Synthetic Wind Generation Records for Australian Wind Farms, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6426, https://doi.org/10.5194/egusphere-egu2020-6426, 2020.

EGU2020-5240 | Displays | ERE2.1

A new spectrum model for the atmospheric crosswind component applicable from mesoscales to microscales

Xiaoli Larsén, Søren Larsen, Erik Petersen, and Torben Mikkelsen

A crosswind spectrum model Sv(f) is proposed that covers both the meso and the microscale, ranging in frequency 1/5 day-1 to the turbulence inertial subrange. The purpose is to improve the calculation of flow meandering effect over areas of the sizes of offshore wind farms and clusters.

The development is based on measurement (from Høvsøre) analysis over this broad frequency range for cases where wind direction does not change much during a day. The model reads:

fSv(f) = Boundary-layer model   for f>f1,

         = Constant                           for f2<f<f1,

         = a1f -2/3 + a2f -2                     for f<f2

Here, the frequency range f2 to f1 defines the gap region, and the constant in this subrange is determined by the spectra on both sides of this range; the boundary-layer model used here is either the Kaimal model or the Mikkelsen-Tchen model; a1 and a2 are climatological coefficients. The credibility of the model is evaluated against with measurements from another wind test site Østerild, with measurements ranging in height from surface layer to a height of 241 m.   

The model is used together with a similar model for the longitudinal wind component u to obtain time series u(t) and v(t), from which direction statistics are obtained and compared with those from measurements. It was found that the boundary-layer models could only describe stationary time series for wind vectors. The new v-spectral model improves significantly the statistics of wind direction variation over scales that correspond to offshore wind farms and clusters.

How to cite: Larsén, X., Larsen, S., Petersen, E., and Mikkelsen, T.: A new spectrum model for the atmospheric crosswind component applicable from mesoscales to microscales, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5240, https://doi.org/10.5194/egusphere-egu2020-5240, 2020.

EGU2020-9538 | Displays | ERE2.1

Multi-decadal offshore wind power variability can be mitigated through optimized European allocation

Charlotte Neubacher, Jan Wohland, and Dirk Witthaut

Wind power generation is a promising technology to reduce greenhouse gas emissions in line with the Paris Agreement.  In the recent years, the global offshore wind market grew around 30% per year but the full potential of this technology is still not fully exploited. In fact, offshore wind power has the potential to generate more than the worldwide energy demand of today. The high variability of wind on many different timescales does, however, pose serious technical challenges for system integration and system security.  With a few exceptions, little focus has been given to multi-decadal variability. Our research therefore focuses on timescales exceeding ten years.

Based on detrended wind data from the coupled centennial reanalysis CERA-20C, we calculate long-term offshore wind power generation time series across Europe and analyze their variability with a focus on the North Sea, the Mediterranean Sea and the Atlantic Ocean. Our approach is based on two independent spectral analysis methods, namely power spectral density and singular spectrum analysis. The latter is particularly well suited for relatively short and noisy time series. In both methods an AR(1)-process is considered as a realistic model for the noisy background. The analysis is complemented by computing the 20yr running mean to also gain insight into long term developments and quantify benefits of large-scale balancing.

We find strong indications for two significant multidecadal modes, which appear consistently independent of the statistical method and at all locations subject to our investigation. Moreover, we reveal potential to mitigate multidecadal offshore wind power generation variability via spatial balancing in Europe. In particular, optimized allocations off the Portuguese coast and in the North Sea allow for considerably more stable wind power generation on multi-decadal time scales.

How to cite: Neubacher, C., Wohland, J., and Witthaut, D.: Multi-decadal offshore wind power variability can be mitigated through optimized European allocation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9538, https://doi.org/10.5194/egusphere-egu2020-9538, 2020.

Analysis of correlation among precipitation, wind, and solar resources could explore their complementary features, enhance the utilization efficiency of renewable energy and further alleviate the carbon emission issues caused by fossil energy. In this study, we discuss the correlation between precipitation and wind, wind and solar, precipitation and solar from various Spatio-temporal perspectives (from east to west in China, in terms of plain, plateau, hill, and mountain, from daily to ten days and monthly) with observed data. With investigation of daily time series of precipitation, wind speed and solar radiation ranging from 1961-1-1 to 2016-12-31 of 726 meteorological stations located in various landform and distributed dispersedly in China, the results show that 1) the fluctuation value, quantified by Mei-Wang Fluctuation index, denotes the descending tendency when the time resolution increases, and this tendency is stronger in the southern and eastern China; 2) the correlation coefficient, characterized by Kendall’s rank correlation coefficient, changes from east to west in China, and the strength of this correlation displays certain connection to the local topography (e.g., in Qinghai province which is located in the plateau region the complementarity between precipitation and wind speed is stronger than that between precipitation and solar, the mid-stream basin of Yangtze River where the topography is scattered and complex has the weaker complementarity compared to other areas in China). According to the results of this research, it is helpful from the temporal perspective to understand the requirement of complementarity in the utilization of wind, and solar resources which are intermittent, and from the spatial perspective to know the solution of mitigating fluctuation via integration of multi-renewable energy situated in different locations.

How to cite: Wang, X.: Analysis of Fluctuation and Correlation Tendency among Precipitation, Wind, and Solar from Various Spatio-temporal Perspectives: a Case Study in China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4931, https://doi.org/10.5194/egusphere-egu2020-4931, 2020.

The Faroe Islands is a small mountainous island group in the north east Atlantic Ocean, located far from any other mainland. The closes adjacent land being Shetland ~300 km away. One electrical power company exists on the islands, distributing power to the ~50.000 citizens. Approximately half of the electrical power comes from renewable energy sources (wind and hydro) and the other half from oil [1]. The political goal is to have the electrical system running 100% on renewable energy sources by 2030. This will presumable be achieved by implementing a significant amount of wind power [2]. The climate in the Faroe Islands is very windy, making it a good area for harvesting wind energy.

As wind is a fluctuating power source, analyzing the wind field and its characteristics is of great importance, when planning implementation of a significant amount of wind power into the power grid. Smoothening of the wind power can be achieved different ways, one being with spatial dispersion of wind farms seen in other studies [3,4]. The spectral characteristics and the smoothening effect of spatial dispersed sites based on wind farm data and meteorological wind speed measurements in the Faroe Islands was shown in a poster presentation at EMS2019 [5]. However, implementing more wind farms requires knowledge of new sites. There have been made NWP calculations of the wind in the Faroe Islands for the period July 2016 to June 2017. NWP are beneficial in the way that they give valuable information at unknown sites, which may be used for wind farm planning. However, NWP calculations are based on a given setup of a simplified reality. Hence, validating any NWP model is needed.

There exists wind measurements at various heights from two meteorological masts at the time period of the mentioned NWP model calculations in the Faroe Islands. The aim of this study is to compare auto- and cross-spectral characteristics of the sets of modelled and measured data. The results will give an insight on the value of NWP derived data for grid integration studies in a region with complex topography.


[1] Framleiðsluroknskapur 2018, SEV, (see http://www.sev.fo/Default.aspx?ID=67)

[2] Hansen, H., Nielsen, T., Thomsen, B., and Andersen, K., 2018, Energilagring på Færøerne, Teknisk opsamlingsrapport. Dansk Energi. (see http://www.os.fo/media/1187/1-teknisk-opsamlingsrapport-energilagring-paa-faer-erne.pdf)

[3] Beyer, H. G., Luther, J., and Steinberger-Willms, R., 1993, Power fluctuations in spatially dispersed wind turbine systems, Solar Energy, Vol. 50, No. 4, pp. 297-305.

[4] Pearre, N. S. and Swan, L. G., 2018, Spatial and geographic heterogeneity of wind turbine farms for temporally decoupled power output, Energy, Vol. 145, pp. 417-429.

[5] Poster presentation at the European Meteorology Society annual meeting 2019, 9-13 September, Copenhagen, Denmark.

How to cite: Poulsen, T. and Beyer, H.-G.: Cross spectral characteristics of modelled and measured sets of spatially distributed wind power in the Faroe Islands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3063, https://doi.org/10.5194/egusphere-egu2020-3063, 2020.

EGU2020-19283 | Displays | ERE2.1

Long-term variability of solar irradiance and its implications for photovoltaic power in West Africa

Ina Neher, Susanne Crewell, Stefanie Meilinger, Uwe Pfeifroth, and Jörg Trentmann

West Africa is one of the least developed regions in the world regarding the energy availability and energy security. Located close to the equator West Africa receives high amounts of global horizontal irradiance (GHI). Thus, solar power and especially photovoltaic (PV) systems seem to be a promising solution to provide electricity with low environmental impact. To plan and to dimension a PV power system climatological data for global horizontal irradiance (GHI) and its variability need to be taken into account. However, ground based measurements of irradiances are not available continuously and cover only a few discrete locations.

Data records of surface irradiance based on satellite measurements have the advantage of covering wide spatial regions and being available over long time periods. The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility on Climate Monitoring (CM SAF) provides the Surface Solar Radiation Data Set-Heliosat, Edition 2.1 (SARAH-2.1), a 35 year long climate data record in an half hourly resolution, covering the whole of Africa and Europe.

In this study, the SARAH-2.1 data record (1983-2017) is used to analyze the impact of 35 years atmospheric variability and trend on GHI and PV yields over West Africa (defined as the region from 3°N to 20°N and 20°W to 16°E). The trend and the variability of solar irradiance is analyzed separately for the wet and dry season as well as for annual data. Furthermore, a simplified model provides high-resolution potential PV yields.

According to the SARAH-2.1 data record, solar irradiance is largest (with up to 300 W/m 2 daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W/m2/decade). Whereas, the solar irradiance is lower in southern West Africa with a negative trend (up to -5 W/m2/decade). The positive trend is mostly connected to the dry season, while the negative trend occurs during the wet season. PV yields show a strong meridional gradient with lowest values around 4 kWh/kWp in southern West Africa and reach more than 5 kWh/kWp in the Sahara and Sahel zone.

This poster will discuss the long-term trend and variability analysis of solar irradiance and highlight the implications for photovoltaic-based power systems in West Africa.

How to cite: Neher, I., Crewell, S., Meilinger, S., Pfeifroth, U., and Trentmann, J.: Long-term variability of solar irradiance and its implications for photovoltaic power in West Africa, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19283, https://doi.org/10.5194/egusphere-egu2020-19283, 2020.

EGU2020-1546 | Displays | ERE2.1

Climate change impacts on wind power density over southeastern Mediterranean

Chris G. Tzanis, Kostas Philippopoulos, Constantinos Cartalis, Konstantinos Granakis, Anastasios Alimissis, and Ioannis Koutsogiannis

Energy production from the utilization of wind energy potential depends on the variability of the wind field as determined by the interaction of natural processes on different scales. Global climate change can cause alterations in the surface wind and thus it may affect the geographical distribution and the wind energy potential variability. Wind energy production is sensitive to wind speed changes, especially in the upper percentile of the wind speed distributions, where energy production is more effective. The importance of wind energy production changes is enhanced by the fact that wind energy investments are long-term and are characterized by high initial costs and low operating costs. In the present study, these changes are examined for the southeastern Mediterranean region, based on simulations of the Regional Climate Model ALADIN 5.2 extracted from the Med-CORDEX database for the climatic scenarios RCP4.5 and RCP8.5. The results indicate a wind power density increase over the Aegean Sea, the Ionian Sea, the Dardanelles and the Black Sea, with similar levels of increase for both climatic scenarios. In contrast, during the winter period there is a decline across the southeastern Mediterranean, which is more significant in the case of the RCP8.5 scenario. Finally, for most areas of eastern Greece, there is a reduction in the number of wind speed cases for both below and above cut-in and cut-out wind speeds, while there is an increase in the number of wind speed cases that wind turbines operate at their maximum power. The results are expected to reduce the uncertainty associated with the impact of climate change on wind energy production. 

How to cite: Tzanis, C. G., Philippopoulos, K., Cartalis, C., Granakis, K., Alimissis, A., and Koutsogiannis, I.: Climate change impacts on wind power density over southeastern Mediterranean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1546, https://doi.org/10.5194/egusphere-egu2020-1546, 2020.

EGU2020-22015 | Displays | ERE2.1

Potential impact of climate change on solar resource in Africa for photovoltaic energy: analyses from CORDEX-AFRICA climate experiments

Adeline Bichet, Benoit Hingray, Guillaume Evin, Arona Diedhiou, Fadel Kebe, and Sandrine Anquetin

The development of renewable electricity in Africa could be massive in coming decades, as a response to the rapid rising electricity demand while complying with the Paris Agreements. This study shows that in the high-resolution climate experiments of CORDEX-AFRICA, the annual mean solar potential is expected to decrease on average by 4% over most of the continent by the end of the century, reaching up to 6% over the Horn of Africa, as a direct result of decrease in solar radiation and increase in air surface temperature. These projections are associated with large uncertainties, in particular over the Sahel and the elevated terrains of eastern Africa. While the expected decrease may affect the sizing of the numerous solar projects planned in Africa for the next decades, this study suggests that it does not endanger their viability. At last, this study indicates that the design of such projects also needs to account for the non-negligible uncertainties associated with the resource.

How to cite: Bichet, A., Hingray, B., Evin, G., Diedhiou, A., Kebe, F., and Anquetin, S.: Potential impact of climate change on solar resource in Africa for photovoltaic energy: analyses from CORDEX-AFRICA climate experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22015, https://doi.org/10.5194/egusphere-egu2020-22015, 2020.

ERE2.2 – Spatial and temporal modelling of renewable energy systems

EGU2020-11328 | Displays | ERE2.2

The cost of undisturbed landscapes: on the valuation of wind turbines in Austria

Sebastian Wehrle and Johannes Schmidt

In Europe, the system cost minimizing highly renewable power system set-up predominantly relies on wind energy, with minor shares of photovoltaics.

Yet, minimizing system cost neglects negative externalities of wind turbines, such as their impact on wildlife, noise emissions, landscape aesthetics, manifesting in local economic impacts such as a decline of house prices in the vicinity of wind turbines.

To better understand the trade-off between electricity system cost and the negative externalities from wind turbines, we quantify the increase in electricity system cost when the system cost minimizing deployment of wind turbines is reduced in the favor of photovoltaics.

Methodologically, we rely on the power system model medea, an open, techno-economic, numerical model of hourly dispatch and investment, set up to resemble the electricity market in Austria and its largest electricity trading partner Germany in 2030, when Austria aims to generate 90% of its electricity consumption from domestic renewable sources on annual balance.

Depending on the capital cost of renewable energy technologies, the marginal system cost from displaced wind turbines can reach up to 40.000 EUR per MW and year or approximately 20 EUR per MWh. Moreover, CO2 emissions can increase by up to 1.2 million tons per year when wind energy is fully displaced. Producer surplus could increase by up to 220 million EUR per annum at intermediate wind energy displacement but falls back towards initial levels when wind energy is fully displaced.

These numbers compare to estimates of property price declines between 2% and 16% caused by wind turbines, depending on the proximity to, and the visibility of the turbine. For illustration, adding a 3.5 MW wind turbine to a total installed wind power capacity of 12.6 GW in Austria over its lifetime (assuming a 3% discount rate) would generate sufficient social value to compensate affected property worth between 0.8 and 6.7 million EUR.

How to cite: Wehrle, S. and Schmidt, J.: The cost of undisturbed landscapes: on the valuation of wind turbines in Austria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11328, https://doi.org/10.5194/egusphere-egu2020-11328, 2020.

EGU2020-20190 | Displays | ERE2.2

The effects of socio-environmental constraints on Norway’s renewable energy potential

Marianne Zeyringer, James Price, and Eline Mannino

The decarbonisation of power production is key to achieving the Paris Agreement goal. Wind and solar energy have matured and decreased in cost rapidly into cost-effective decarbonisation solutions. However, the location of renewables effects the impact on the environment and the communities they are sited. Thus, socio-environmental constraints can strongly limit the overall capacity potential affecting the technology choices, resulting costs and political feasibilities of reaching the national emission reduction targets. Nevertheless, socio-environmental acceptance is usually not considered when studying the transition to a net-zero energy system.

Norway has one of the best wind energy potentials in Europe and a large scale deployment in combination with increased interconnection could have effects on the rest of the European power system. However, recent projects have been facing large opposition. This may be surprising as Norway has very low population density but the right to unspoilt nature is strongly anchored in the Norwegian culture and Sami reindeer herding could be disturbed by wind projects.  In 2019 the Norwegian Water Resources and Energy Directorate (NVE) proposed a national framework for wind energy which defined the most suitable areas for wind energy development. After massive protests the framework was recently withdrawn by the government. Offshore wind energy is often seen as a potential solution as socio-environmental opposition is expected to be lower but it is more expensive. However, it is as socio-political decision to choose a more expensive technology, site or mitigation option. A spatially-dependent capacity assessment under different socio-environmental scenarios and their effect on energy system design is missing to allow for such discussion.

Here, we close this gap by analysing the NVE framework, previous concessions and related opinions, literature, newspaper articles and perform interviews with key stakeholders to design three scenarios of socio-environmental acceptability for onshore/offshore wind and solar energy. Based on the here developed scenarios we then conduct a GIS analysis to determine the spatially dependent capacity potential per technology and scenario. Finally, we implement these geospatial capacity scenarios into a high spatial and temporal resolution electricity system model for Europe (“highRES Europe”) to analyse the effects on the Norwegian and European electricity system design in 2050.  

How to cite: Zeyringer, M., Price, J., and Mannino, E.: The effects of socio-environmental constraints on Norway’s renewable energy potential, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20190, https://doi.org/10.5194/egusphere-egu2020-20190, 2020.

EGU2020-5708 | Displays | ERE2.2

The implications of landscape visual impact on future highly renewable power systems: a case study for Great Britain

James Price, Kai Mainzer, Stefan Petrović, Marianne Zeyringer, and Russell McKenna

The decarbonisation of power production is key to achieving the Paris Agreement goal of limiting global mean surface temperature rise to well below 2°C, particularly so given the drive to electricity transport and heat. At the same time, variable renewable energy (VRE) sources such as solar photovoltaics (PV) and wind have seen rapid cost reductions in recent decades bringing them into cost parity with base load fossil generation. Therefore, recent long term planning studies, which utilise cost-optimising models, have demonstrated the important role of VREs in decarbonising power systems across the world. However, while techno-economically detailed, such studies tend to neglect key social factors that often shape the real world evolution of the energy system.

Of particular relevance to VRE deployment is their visual impact on the landscape which can act to undermine their public acceptability. Here, we use crowd-sourced scenicness data to derive spatially explicit, empirically grounded wind energy capacity potentials for three scenarios of public sensitivity to this visual impact. We augment these with a detailed analysis of Great Britain’s (GB) solar PV capacity potential. We then use these scenarios in a cost-optimising model of GB’s power system to assess their impact on the cost and design of the electricity system in 2050. Our results show that the levelised cost of the system can increase by up to 15% when public sensitivity to visual impact is high compared to low. In part this is driven by our finding that some of the most picturesque parts of GB also happen to be the most cost-effective for onshore wind, leading to large reductions in installed capacity as we move through our sensitivity scenarios. Indeed, deployment is heavily limited in Scotland and the South-West which in turn acts to limit the spatial diversity of onshore wind. We conclude that it is essential for policy makers to consider these cost implications and to find mechanisms to ameliorate the visual impact of onshore wind in local communities.

How to cite: Price, J., Mainzer, K., Petrović, S., Zeyringer, M., and McKenna, R.: The implications of landscape visual impact on future highly renewable power systems: a case study for Great Britain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5708, https://doi.org/10.5194/egusphere-egu2020-5708, 2020.

EGU2020-4176 | Displays | ERE2.2

Incorporating the value of nature into assessments of future energy pathways

Andrew Lovett, Brett Day, Greg Smith, Gemma Delafield, Nathan Owen, Paolo Agnolucci, Ian Bateman, Nicola Beaumont, Steve Carver, Trudie Dockerty, Caspar Donnison, Felix Eigenbrod, Henry Ferguson-Gow, Astley Hastings, Robert Holland, Richard Pearson, Gilla Sünnenberg, Gail Taylor, and Guy Ziv

The UK government has made formal commitments to reduce GHG emissions (e.g. under the Climate Change Act 2008 and subsequent amendments) and to protect/improve natural capital and the environment (e.g. as part of the 25 Year Environment Plan published in 2018). Meeting these objectives requires an integrated approach to two parallel challenges i) decarbonising the energy system and ii) better understanding and valuation of natural capital and ecosystem services. From an academic perspective this involves bringing together two substantial, but rather weakly connected bodies of research, while also acknowledging that this integration in a UK setting needs to recognise the international context (i.e. a whole systems perspective).

The ADVENT project (ADdressing Valuation of Energy and Nature Together) has been funded by the UK National Environment Research Council to develop conceptual frameworks and modelling tools which ‘integrate the analysis of prospective UK energy pathways with considerations relating to the value of natural capital’. A methodology has been implemented to downscale the outputs of pathways from national energy system models and incorporate environmental impacts into the assessment of different options. This has required defining spatially-optimised distributions of investments in new energy infrastructure using a range of financial and welfare criteria. These distributions are then compared in terms of their construction, transport and land opportunity costs, as well as the implications for biodiversity, greenhouse gas emissions, recreation, visual amenity and water resources.

This paper will present results from comparing different UK energy pathways through to 2050 in terms of the implications of electricity generation from three types of renewables (bioenergy, solar and onshore wind). The results illustrate that i) individual pathways can vary appreciably in their environmental impacts, ii) overall societal welfare can be enhanced by using spatial modelling to incorporate valuations of such impacts into implementation of pathways and iii) assessment outcomes can be sensitive to modelling assumptions (e.g. regarding the proportion of biomass feedstock from domestic or international sources). More broadly, the results demonstrate how important improvements can be achieved in the integration of environmental considerations into the assessment of future energy pathways at regional and national scales. The approach is now being further refined through the UK Energy Research Centre Phase 4 programme and ADVANCES Landscape Decisions project in the UK, as well as the five-country IRENES project funded by Interreg Europe. 

How to cite: Lovett, A., Day, B., Smith, G., Delafield, G., Owen, N., Agnolucci, P., Bateman, I., Beaumont, N., Carver, S., Dockerty, T., Donnison, C., Eigenbrod, F., Ferguson-Gow, H., Hastings, A., Holland, R., Pearson, R., Sünnenberg, G., Taylor, G., and Ziv, G.: Incorporating the value of nature into assessments of future energy pathways, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4176, https://doi.org/10.5194/egusphere-egu2020-4176, 2020.

EGU2020-8139 | Displays | ERE2.2

Facility-specific environmental footprints of wind and solar power at a global scale

Joyce Bosmans, Tine Dammeier, and Mark Huijbregts

Wind and solar power are vital for climate change mitigation, producing electricity at much lower greenhouse gas (GHG) emissions than conventional fossil-based technologies. Here, we obtain facility-specific environmental footprints of utility-scale wind and solar power across the globe. We investigate how the GHG footprint of wind and solar power varies across space and across technological characteristics. We will furthermore investigate other environmental footprints such as mineral resource scarcity to assess whether there is a trade-off between low GHG footprints and possibly higher other footprints.

We use facility-specific technological characteristics of ~30,000 wind parks and ~10,000 photovoltaic solar parks across the globe, such as capacity, hub height, rotor diameter or type of panel, to determine the life-cycle environmental impacts per wind or solar park. The produced power per facility over its lifetime is computed based on technological characteristics as well as location-specific hourly climate input from the ERA5 reanalysis dataset. The environmental footprint is then defined as impact divided by power produced, e.g. g CO2-eq/kWh, to allow for comparison between facilities and across energy sources.

The facility-specific footprints will be shown on maps to indicate spatial variability and range of footprints of both wind and solar power. We will furthermore investigate the variability in footprints using analysis of variance, in order to indicate whether climate (i.e. location-specific wind or radiation) or technological characteristics (i.e. hub height, rotor diameter or type of panel) is the main cause of variability in footprints.

How to cite: Bosmans, J., Dammeier, T., and Huijbregts, M.: Facility-specific environmental footprints of wind and solar power at a global scale, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8139, https://doi.org/10.5194/egusphere-egu2020-8139, 2020.

EGU2020-21830 | Displays | ERE2.2

Modelling long term investments in wind energy – benefits of combining high resolution geo data, energy system modelling and auction design

Frieder Borggrefe, Simak Sheykhha, Kai von Krbek, and Yvonne Scholz

This paper addresses the link between geo data models, market design of renewable energy auctions and energy system models. Renewable energy accounts for around 20% of electricity supply in Europe. In countries such as Sweden, Finland and Germany we already reached a share of more than 40%. In these countries renewables became the main energy source. The dash for building renewable energy in Europe will continue with the EU and national climate targets.

The impact of renewables on the grid and system operation will increase. Key elements to build an efficient energy infrastructure in the long term are a good understanding on (1) how renewables will penetrate the energy system (regional investments) and a good perception on (2) the effects renewables have on the energy system including (3) the additional infrastructure required, enabling a secure electricity system.

Since 2005 the DLR uses geo data model ENDAT to predict wind power feed-in and investments in the years up to 2050 based on historic weather data. In order to allow for better modelling of the potentials of wind energy high resolution of wind data and efficient clustering methods are applied to allow a more detailed representation of the long term potentials of wind energy.

In this paper we combine three modelling approaches: The geo data model ENDAT (DLR), a model of the renewable auctions based on a system dynamics model HECTOR (RWTH Aachen) and an energy system model REMix (DLR) – that allows investigating the long term impact of renewables on the electricity system for 2030, 2040 and 2050. The key questions this paper aims to answer are: How will detailed spatial and temporal modelling of renewable energy data as well as auction design influence the predictions for future distribution of wind power plants? What policy recommendations can be drawn from predictions for the years up to 2050 with regard to policy design and investments in wind energy in Germany and Europe?

The paper divides in two parts. The first part investigates different approaches to model potential for wind power investments and power generation based on historic wind data. While in the past ENDAT used to generate time series for wind on a country by country basis or on NUTS-1 level, improved models allow for more detailed representation of wind data. Key element of this part is to understand the benefits of high resolution of wind data for the results of the overall energy system modelling.

The second part of the paper describes how the detailed representation of wind potentials and wind speeds will affect future auction results - and therefore influence long term investments in renewable energy. Model results for the German electricity system will be presented. To benchmark different scenarios, each scenario will be evaluated based on the regional distribution of renewable energies and the resulting impact on the energy system (with regard to grid investments, operation costs and aspects of security of supply).

How to cite: Borggrefe, F., Sheykhha, S., von Krbek, K., and Scholz, Y.: Modelling long term investments in wind energy – benefits of combining high resolution geo data, energy system modelling and auction design, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21830, https://doi.org/10.5194/egusphere-egu2020-21830, 2020.

EGU2020-3008 | Displays | ERE2.2

Understanding multidecadal variability for energy system studies: can current 20th century reanalyses do the job?

Jan Wohland, Hannah Bloomfield, David Brayshaw, Stefan Pfenninger, and Martin Wild

The variability of renewable power generation is often quantified based on modern reanalyses such as ERA5 or MERRA-2 which provide climatic information over the last few decades. Compared to infrastructure lifetimes, modern reanalyses cover only short periods and may consequently fail to sample relevant longer-term climate variability. While there is evidence for multi-decadal variability in wind power generation [Wohland et al. (2019), Zeng et al. (2019)], hydropower [Bonnet et al. (2017)] and solar energy [Sweerts et al. (2019)], a consistent treatment of multi-decadal variability has not been achieved. 

This knowledge barrier can potentially be overcome using 20th century reanalyses which provide internally consistent fields of energy-relevant variables (e.g., solar radiation, precipitation, temperature and wind). However, the provision of reliable climatic information on these timescales is known to be a challenge due to, for example, the evolution of measurement techniques. Some cases of spurious trends and other shortcomings of the datasets are known. It is therefore of utmost importance to quantify uncertainties prior to usage in energy system studies. To this end, we systematically compare 20CRv3, 20CRv2c, CERA20C and ERA20C with respect to variables needed in renewable energy assessments and report similarities and discrepancies accross the datasets. The focus is given to substantial differences with respect to multi-decadal solar radiation variability in Europe, also known as dimming and brightening. 


References

Bonnet, R., Boé, J., Dayon, G. & Martin, E. Twentieth-Century Hydrometeorological Reconstructions to Study the Multidecadal Variations of the Water Cycle Over France. Water Resour. Res. 53, 8366–8382 (2017).

Sweerts, B. et al. Estimation of losses in solar energy production from air pollution in China since 1960 using surface radiation data. Nat Energy 4, 657–663 (2019).

Wohland, J., Omrani, N. E., Keenlyside, N. & Witthaut, D. Significant multidecadal variability in German wind energy generation. Wind Energ. Sci. 4, 515–526 (2019).

Zeng, Z. et al. A reversal in global terrestrial stilling and its implications for wind energy production. Nat. Clim. Chang. (2019).

How to cite: Wohland, J., Bloomfield, H., Brayshaw, D., Pfenninger, S., and Wild, M.: Understanding multidecadal variability for energy system studies: can current 20th century reanalyses do the job?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3008, https://doi.org/10.5194/egusphere-egu2020-3008, 2020.

EGU2020-21859 | Displays | ERE2.2

Optimal location and sizing of small hybrid systems in micro-grid system using Volunteer Geographic Information

Javier Valdes, Sebastian Wöllmann, and Roland Zink

Optimal location and sizing of small hybrid systems in micro-grid system using Volunteer Geographic Information

 

This study presents an optimization model for the optimal location and sizing of small hybrid systems in simulated micro-grids. By using an optimization model - in combination with COSMO-REA2 weather data - various micro-grids local energy systems are simulated using the Calliope energy simulation model. The Calliope optimization and simulation model is feed with GIS-data from different Volunteered Geographic Information projects, including OpenStreetMap. These allows to automatically allocate specific demand profiles to diverse OpenStreetMap building categories. Moreover, based on the characteristics of the OpenStreetMap data, a set of possible distributed energy resources) including renewables and fossil fueled generators are defined for each building category. The optimization model is applied for a set of scenarios based on different electricity prices and technological characteristics. This allows to assess the impact and profitability of the different technological options on the micro-grid configuration. Moreover, in order to assess the impact of each of the scenarios on the current distribution infrastructure, the results of the simulations are included on an existing model of the low and middle voltage network for Lower Bavaria, Germany. Finally, to facilitate their dissemination, the results of the simulation are stored in a PostgreSQL database, before they are delivered by a RESTful Laravel Server and displayed in an Angular Web-Application.

How to cite: Valdes, J., Wöllmann, S., and Zink, R.: Optimal location and sizing of small hybrid systems in micro-grid system using Volunteer Geographic Information, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21859, https://doi.org/10.5194/egusphere-egu2020-21859, 2020.

EGU2020-3399 | Displays | ERE2.2

Power usage in the transport sector – potential, costs and greenhouse gas abatement of different well-to-wheel pathways

Markus Millinger, Philip Tafarte, Matthias Jordan, Alena Hahn, Kathleen Meisel, and Daniela Thrän

The increase of variable renewable energy sources (VRE), i.e. wind and solar power, may lead to a certain mismatch between power demand and supply. At the same time, in order to decarbonise the heat and transport sectors, power-based solutions are often seen as promising option, through so-called sector coupling. At times when VRE power supply exceeds demand, the surplus power could be used for producing liquid and gaseous electrofuels. The power is used for electrolysis, producing hydrogen, which can in turn be used either directly or combined with a carbon source to produce hydrocarbon fuels.

Here, we analyse the potential development of surplus power for the case of Germany, at an ambitious VRE expansion until 2050 and perform a cost analysis of electrofuels at different production levels using sorted residual load curves. These are then compared to biofuels and electric vehicles with the aid of an optimisation model, considering both cost- and greenhouse gas (GHG)-optimal options for the main transport sectors in Germany.

We find that, although hydrocarbon electrofuels are more expensive than their main renewable competitors, i.e. biofuels, they are most likely indispensable in addition for reaching climate targets in transport. However, the electrofuel potential is constrained by the availability of both surplus power and carbon. In fact, the surplus power potential is projected to remain limited even at currently ambitious VRE targets for Germany and carbon availability is lower in an increasingly renewable energy system unless direct air capture is deployed. In addition, as the power mix is likely to contain fossil fuels for decades to come, electrofuels based on power directly from the mix with associated conversion losses would cause higher GHG-emissions than the fossil transport fuel reference until a very high share of renewables in the power source is achieved. In contrast, electric vehicles are a more climate competitive option under the projected power mix with remaining fossil fuel fractions, due to a superior fuel economy and thereby lower costs and emissions.

As part of the assessment, we quantify the greenhouse gas abatement costs for different well-to-wheel pathways and provide an analysis and recommendations for a transition to sustainable transport.

How to cite: Millinger, M., Tafarte, P., Jordan, M., Hahn, A., Meisel, K., and Thrän, D.: Power usage in the transport sector – potential, costs and greenhouse gas abatement of different well-to-wheel pathways, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3399, https://doi.org/10.5194/egusphere-egu2020-3399, 2020.

EGU2020-3644 | Displays | ERE2.2

Coupling energy, meteorology, hydrology and climate science to optimize renewable power planning in West Africa

Sebastian Sterl, Inne Vanderkelen, Celray James Chawanda, Nicole van Lipzig, Ann van Griensven, and Wim Thiery

Many countries in the developing world have immense, but underexploited, renewable electricity potentials. A good example are the countries in the Economic Community of West African States (ECOWAS). Historically, renewable power generation in West Africa has focused on hydropower, which produces around 20% of the region’s overall electricity generation, with natural gas providing most of the remainder; future capacity expansion plans for the region are also focused to a large extent around gas and hydropower.

 

However, dropping costs for modern renewable power sources, primarily solar photovoltaic and wind power, are expected to break the West African gas-hydro-paradigm in the near future. Given the currently low levels of generation and strongly increasing power demand in many countries, they can be seen as “greenfields” for integrating variable renewable energy (VRE) sources into stable power mixes and planning transmission capacity expansion to the benefit of VRE sources.

 

Such planning requires a nuanced view of the role that different resources can play in a power mix. Solar and wind power are clean and have low environmental impact, but show pronounced diurnal and seasonal cycles, which requires increased power system flexibility across a wide range of time scales. Globally, such flexibility is currently mostly delivered by natural gas, whose use in the future must be limited to comply with the goals of the Paris Agreement. Reservoir hydropower is an alternative source of flexibility, but only if adequately managed across all involved time scales and without endangering environmental flow requirements.

 

In this research, we combined energy science, meteorology, hydrology and climatology to conduct a scenario-based analysis of smart renewable expansion strategies for West Africa using the REVUB model, considering all time scales ranging from hourly to decadal (including climate change effects) and all spatial scales from point to subcontinental. We show that smart management of hydropower plants, smart designs of solar-wind mixes, and smart planning of regional interconnections can ensure reliable and stable power provision while reducing future natural gas demand and at the same time avoiding ecologically damaging hydropower overexploitation. These results have wide implications for energy policy planning far beyond West Africa, particularly in hydro-dependent developing countries.

How to cite: Sterl, S., Vanderkelen, I., Chawanda, C. J., van Lipzig, N., van Griensven, A., and Thiery, W.: Coupling energy, meteorology, hydrology and climate science to optimize renewable power planning in West Africa, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3644, https://doi.org/10.5194/egusphere-egu2020-3644, 2020.

EGU2020-4682 | Displays | ERE2.2

Weather data modelling for energy system models using machine learning

Alexander Kies, Nishtha Srivastava, Kai Zhou, Jan Steinheimer, and Horst Stoecker

Weather data is essential to model and optimise energy systems, which are based on high shares of renewable generation sources. However, differences between data sources can be significant and often little emphasis is put on energy-related variables such as hub-height wind speeds.

In this work, we use generative adversarial networks (GAN), a class of machine learning systems, to model weather data for large-scale energy system models and optimise energy systems of different scales and sizes.

We show that generating weather data using GAN saves effort as required for processing large amounts of weather data and that it can reliably reproduce results from using weather data produced by numerical models.

How to cite: Kies, A., Srivastava, N., Zhou, K., Steinheimer, J., and Stoecker, H.: Weather data modelling for energy system models using machine learning, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4682, https://doi.org/10.5194/egusphere-egu2020-4682, 2020.

Results on the statistical properties of internal variability of annual mean surface solar radiation (SSR) and associated decadal scale trends are presented, following in part Folini et al. 2017 (doi:10.1002/2016JD025869). Estimates are based on 43 pre-industrial control (piControl) experiments of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Trends are shown to depend strongly on geographical region and on whether they are quantified in absolute units or relative to the long term mean SSR. Providing one map for absolute and one map for relative trends is sufficient, as approximate analytical relations are shown to hold between trends of different length and likelihood and the standard deviation of the underlying SSR time series. Comparison with present-day observations and inter-model spread suggest an average uncertainty of these estimates of about 30%.  Intermodel spread suggests that regional uncertainties can be up to about three times larger or smaller. Using the model by Crook et al. 2011 (doi:10.1039/C1EE01495A) to translate SSR into PV production, associated internal variability of photo voltaic (PV) energy production is inferred. Results suggest that it is plausible for PV production to change by several per cent over a decade just because of internal variability.

How to cite: Folini, D.: Internal variability of surface solar radiation and associated PV production, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5141, https://doi.org/10.5194/egusphere-egu2020-5141, 2020.

EGU2020-7231 | Displays | ERE2.2

Modeling spatial and temporal charging demands for electric vehicles for scenarios with an increasing share of renewable energies

Philip Gauglitz, Jan Ulffers, Gyde Thomsen, Felix Frischmuth, David Geiger, Michael von Bonin, Daniel Horst, and Alexander Scheidler

The electrification of the transport sector together with an increasing share of renewable energies has the potential to reduce CO2 emissions significantly. This transformation requires the roll-out of charging infrastructure, which, as a new and rapidly growing electrical consumer, has an impact on the power grid. For grid planning and dimensioning purposes, it is crucial to assess this impact as accurately as possible. Consequently, the possibility to simulate potential spatial distributions of charging points and their ramp-up is of central importance. We present an approach using socio-economic data such as population size, income levels and age to estimate where electric mobility will be concentrated, especially during the transition phase.

Suitable socio-economic data for Germany is only available for the current population and, in terms of spatial resolution, at the level of streets. Thus, both spatial disaggregation and temporal extrapolation within a demographic model are necessary for more detailed scenario predictions. In our proposed approach, a fuzzy-string comparison method and geographical mapping are used to allocate the socio-economic data to buildings (LOD1). A prediction on demographic changes taking into account recent municipal developments in Germany has been implemented. Age-specific changes at the community level are disaggregated on the household level and merged with socio-economic data. Combined with framework scenarios, we use these criteria based on socio-economic factors to develop spatially disaggregated scenarios. The framework scenarios take into account an increased penetration of renewable energies and a developed TCO approach for the ramp-up of electric mobility.

Predicting future distributions of domestic charging points with such a level of detail in terms of the ramp-up model and spatial resolution is highly beneficial for grid analysis and planning purposes. Typically, distribution grid studies that assess necessary grid investments rely on various simplified assumptions. A more detailed analysis of when and where the power flow at certain building connection points is likely to increase allows for more precise analyses of possible grid congestions. This also makes more efficient grid reinforcement and expansion planning possible, especially in urban areas, where infrastructure changes are expensive and time-consuming.

Another important aspect for demand-driven grid planning is the temporal modeling of charging processes. We use individual driving profiles based on surveys to create charging profiles for different consumer types. We combine them with a holistic model of the energy system including power plant scheduling as well as other (future) local producers and consumers such as photovoltaics and heat pumps. It allows us to consider correlations and simultaneities in their behavior and additionally enables us to explore various flexibility options and their influence on the electricity market and the grid.

How to cite: Gauglitz, P., Ulffers, J., Thomsen, G., Frischmuth, F., Geiger, D., von Bonin, M., Horst, D., and Scheidler, A.: Modeling spatial and temporal charging demands for electric vehicles for scenarios with an increasing share of renewable energies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7231, https://doi.org/10.5194/egusphere-egu2020-7231, 2020.

EGU2020-7771 | Displays | ERE2.2

Application of portfolio theory to the wind-solar energy mix in Spain: climate-related risks and opportunities

Aina Maimó-Far, Alexis Tantet, Víctor Homar, and Philippe Drobinski

Non-hydroelectric renewable energy sources (RES) are the fastest growing energy generation technologies in terms of new capacity and their penetration is expected to double in the next 20 years. More than half of this growth is expected to come from wind power. However, given the variable nature of RES production linked to climate variability and the need for a constant supply-demand balance, increasing penetration of renewables raises structural, technological and economical issues. In Spain, the correlation of solar and wind climate potential with the seasonal fluctuation of electricity consumption, associated mostly with tourism activity, allows for some ambitious renewable penetration scenarios. This work aims at identifying optimal energy mix scenarios that maximize RES penetration while minimizing distribution risk, using the Markowitz modern portfolio theory as a starting point. We apply the e4clim model to the Spanish electricity system, using reanalysis and electricity data in order to produce scenarios for optimal geographical and technological distribution of RES installed capacity. We conduct a mean-risk analysis and discuss the geographical distribution for the most relevant optimal scenarios. We also provide an interpretation of the optimal RES penetration results in terms of the regional climatic characteristics of Spain. Beyond the large potential of the regional climates of Spain to exploit RES technologies, optimal scenario results reveal interesting regional differences with respect to the current installed capacities, which can be linked to economic and regulatory regional contexts.

How to cite: Maimó-Far, A., Tantet, A., Homar, V., and Drobinski, P.: Application of portfolio theory to the wind-solar energy mix in Spain: climate-related risks and opportunities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7771, https://doi.org/10.5194/egusphere-egu2020-7771, 2020.

EGU2020-8154 | Displays | ERE2.2

Using a neural network approach to correct for systematic biases in seasonal wind power electricity generation forecasting

Johann Baumgartner, Johannes Schmidt, and Katharina Gruber

Neural networks are widely applicable for different modelling purposes in the energy sector such as predictions of electricity generation from wind and solar resources as well as electricity demand and prices. However, neural network approaches heavily rely on the availability of sound climate and actual generation data for model training. Sufficiently long and accurate time series of climate data needed for model training and seasonal climate forecasts for the prediction process are often not available from a data source based on the same climate model for the corresponding study area. Most likely data sources based on different climate models also feature different bias and consequently using one data source for model training and using another one for model prediction will produce systematically biased results that need correction.

Therefore, we assess here if a neural network approach can be successfully applied as a means to correct for systematic biases when a neural network is trained on wind power electricity generation while using a different climate data source for the prediction process.

We apply neural networks on climate assimilation data from climate modelling and train the neural network on actual generation from wind power. The trained neural networks are then used with an ensemble of climate input variables from seasonal forecasts to seasonally predict electricity generation from wind power. As the neural network is trained on a different data source, the modelled generation values are systematically biased. A subsequent neural network is applied to reduce this bias and to gain insight into how the bias between the two data sources differs via an analysis of the networks weights as well as a sensitivity analysis.

The neural network’s ability to correct for systematic biases is assessed based on whether the quality of the modelled distributions in terms of their seasonal characteristics and extreme event frequencies is improved compared to not using this bias correcting neural network. Initial model results show that a neural network can in fact be used to correct for systematic biases introduced by using different data sources in model training and prediction to help generate results of improved quality versus not using a bias correcting neural network.

How to cite: Baumgartner, J., Schmidt, J., and Gruber, K.: Using a neural network approach to correct for systematic biases in seasonal wind power electricity generation forecasting, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8154, https://doi.org/10.5194/egusphere-egu2020-8154, 2020.

EGU2020-9249 | Displays | ERE2.2

The Feasibility of Photovoltaic Pumping System For Apple Orchards Irrigation in Loess Plateau

Miao Sun, Xining Zhao, Xuerui Gao, and Yubao Wang

Rainwater collection and utilization is a common method to relieve soil water pressure in dry dryland orchards. Due to relatively low levels of economic development and population distribution, these areas are unable to develop electricity or import large amounts of energy, resulting in rainwater harvesting often not being fully utilized. Photovoltaic (PV) pumping system is an effective way to ensure the sustainable utilization of soil water in apple orchards. In order to explore the application potential of PV pumping system in the apple suitable area of the loess plateau, this study simulates the rainwater collection amount and the orchard water demand change process in typical hydrological years and conducts a feasibility analysis of the PV pumping system from both technical and economic perspectives. The results found that the precipitation from June to October could not meet the water requirement of the growth of apple tree in the demonstration orchard and the total annual water demand reaches 170 m³. Fortunately, the local solar energy resources can basically meet the demand for solar energy in the PV pumping irrigation system, which ensures sufficiently irrigation water for the apple trees grow. After the completion of the PV pumping irrigation system, the income from the increase in fresh grass production in the demonstration area will reach 8019 CNY/year. The ratio of investment to income is 1:3.0. The investment recovery period is 4 years and it has good economic feasibility. Finally, using spatial geographic information technology, the apple-adapted area is systematically matched with the most suitable planting area for solar irrigation. The land area suitable for solar technology irrigation accounts for 47.6% of the total area, showing promising prospects to be popularized in Western China at large scale.

KEY WORDS: photovoltaic pumping System; Loess plateau; economic benefit; application potential; Apple orchards

How to cite: Sun, M., Zhao, X., Gao, X., and Wang, Y.: The Feasibility of Photovoltaic Pumping System For Apple Orchards Irrigation in Loess Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9249, https://doi.org/10.5194/egusphere-egu2020-9249, 2020.

EGU2020-9961 | Displays | ERE2.2

The role of spatial resolution of climate data for the quality of simulated wind power generation – A multi-country analysis

Katharina Gruber, Johann Baumgartner, Claude Klöckl, Peter Regner, and Johannes Schmidt

Integration of a high share of renewables into the energy system comes with its implications. In order to study long and short-term effects on the electrical system, long time series of power generation with high spatial resolution are necessary. In recent years, reanalysis data have become a popular resource for obtaining these power generation datasets, however with the drawback of a rather coarse spatial resolution of several kilometres (MERRA-2: approx. 50km, ERA5: approx. 31 km). In order to overcome this limitation, reanalysis datasets can be combined with other datasets with a higher spatial resolution.

In the present study, we assess whether applying the Global Wind Atlas (GWA) developed by the Technical University of Denmark with a spatial resolution of 1 km can improve wind power generation simulated from two reanalysis (MERRA-2 and ERA5)  datasets when compared to observed power generation. Furthermore, these two reanalysis datasets are compared to determine how different spatial resolution of underlying reanalysis datasets affects the resulting time series. Wind power generation is simulated from reanalysis wind speeds based on a physical model. For wind speed bias correction to specific locations, mean wind speeds are approximated to GWA wind speeds. A turbine-specific power curve model scaled by the turbine specific power is applied to account for different technical performance. The analysis is conducted for different regions of the world (USA, Brazil, Austria, South Africa) and for different spatial and temporal levels, to determine how different datasets perform on different spatio-temporal scales.

Preliminary results show that bias correction with the GWA has a positive impact on simulation results for MERRA-2, the dataset with lower spatial resolution, while the effect for ERA5 is ambiguous. The error between simulated and observed wind power generation time series can be decreased by spatial and temporal aggregation and a positive, but not very strong correlation between system size (defined by a wind-correlation indicator) and simulation quality (higher correlation, lower error measures) could be identified.

Based on these results, we recommend applying additional wind speed bias correction on datasets with rather coarse spatial resolution, while the quality of newer datasets with high spatial resolution may be sufficient to be used without additional bias correction.

How to cite: Gruber, K., Baumgartner, J., Klöckl, C., Regner, P., and Schmidt, J.: The role of spatial resolution of climate data for the quality of simulated wind power generation – A multi-country analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9961, https://doi.org/10.5194/egusphere-egu2020-9961, 2020.

EGU2020-10357 | Displays | ERE2.2

Geo.KW - Coupling hydrothermal and infrastructure modeling at urban scale for an efficient use of shallow geothermal energy

Thilo Schramm, Helmut Heller, Fabian Böttcher, Smajil Halilovic, Leonhard Odersky, Kyle Davis, Thomas Hamacher, Mirjam Mehl, and Kai Zosseder

To reduce anthropogenic climate change, the energy demand from all energy sectors has to be met by renewable energies, wherever possible.
Shallow geothermal energy usage, powered by green electricity, provides heating/cooling at a high level of efficiency, which is difficult to achieve with renewable energy alone.
We have created a coupling approach, which combines hydrothermal and infrastructure modeling at an urban scale to efficiently position shallow geothermal systems between existing power plants and conflicting groundwater usage, optimised by economical and ecological contraints.
We are using Pflotran, a finite volume Darcy-Richards model for our hydrothermal model.
The implementation of the energy infrastructure is done with urbs, a linear optimisation model for distributed energy systems.
We utilize preCICE, a coupling library for multi-physics simulations, for fully parallel peer-to-peer data exchange between these modeling domains.
Iterative optimization is meant to ensure the convergence of the fully coupled model.

How to cite: Schramm, T., Heller, H., Böttcher, F., Halilovic, S., Odersky, L., Davis, K., Hamacher, T., Mehl, M., and Zosseder, K.: Geo.KW - Coupling hydrothermal and infrastructure modeling at urban scale for an efficient use of shallow geothermal energy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10357, https://doi.org/10.5194/egusphere-egu2020-10357, 2020.

EGU2020-14476 | Displays | ERE2.2

Evaluation and applicability of the spatio-temporal complementarity of the solar and wind resources for the optimized design of renewable energy scenarios

Sonia Jerez, Javier Mellado-Cano, Raquel Lorente-Plazas, Pedro Jiménez-Guerrero, Juan Andrés García-Valero, and Juan Pedro Montávez

We present and test a parsimonious model to help designing optimized wind and photovoltaic fleets, e.g. guaranteeing that the renewable production closely follows the electricity demand curve or any other optimization criteria. First, time-series of weather variables, from high-resolution gridded datasets, are transformed into time-series of wind and PV power potential production, which can be seen as capacity factor (CF) estimates. Second, a combination of hierarchical and non-hierarchical clustering is performed to identify regions with similar temporal variability of the CF series. Third, a linear combination of the resulting mean regional CF series is constructed to be fitted, for instance, to get the best production-demand adjustment, or under alternative optimization criteria such as minimum cost of installations that guarantee a certain supply. The coefficients obtained for each CF series after the fitting or optimization exercise, to which the condition of being zero or positive must be imposed and which, optionally, could be individually forced to vary within a certain range, will indicate the optimum amount of installed power capacity needed in the each region under the chosen optimization criteria. Illustrating the method, it has been applied over Europe at the monthly time-scale using the ERA5 reanalysis, but its applicability in other spatial and temporal scales is immediate. The results support its utility to design optimized renewable energy scenarios.

ACKNOWLEDGMENTS: This work is supported by the projects CLIMAX (20642/JLI/18) funded by the Fundación Séneca – Agencia de Ciencia y Tecnología de la Región de Murcia, and EASE (RTI2018-100870-A-I00) funded by the Spanish Ministry of Science, Innovation and Universities.

How to cite: Jerez, S., Mellado-Cano, J., Lorente-Plazas, R., Jiménez-Guerrero, P., García-Valero, J. A., and Montávez, J. P.: Evaluation and applicability of the spatio-temporal complementarity of the solar and wind resources for the optimized design of renewable energy scenarios, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14476, https://doi.org/10.5194/egusphere-egu2020-14476, 2020.

EGU2020-15541 | Displays | ERE2.2

A validated method for estimating regional electricity demand from national time-series

Laurens Stoop, Ad Feelders, and Machteld van den Broek

The share of renewable energy in the electrical grid will likely increase as mitigation measures for future climate change are put into effect. Renewable energy production, such as wind and solar, is largely dependent on the weather and is thus subject to variability on (sub-)daily, weekly and yearly timescales. To facilitate a smooth transition of the energy system, it is necessary to have a thorough knowledge of such a future energy system on hourly level for multiple years. 

Information on the optimal spatial distribution of renewable energy sources, on the supply patterns of different renewable energy sources, and on the cost-effective operation of such a system can be obtained through a variety of methods. For each of these methods intricate knowledge of the regional electricity demand is essential, as without it you have no insights into the required installed capacity, the regional size and sign of the weather-induced impact, or to what degree units have to be committed. 

While in general the knowledge on (renewable) energy systems has steadily increased, the knowledge on the demand for electricity is still basically the same as 20 years ago. The reason for this is simple: sub-national demand data has not been measured until recently and is still not readily available to the public and thus to researchers. Therefore the possibility to study the sub-national demand for electricity in more detail is limited.

The aim of the presented work is to show that national demand time-series can be spatially disaggregated by taking the population distribution and the spatio-temporal variation of temperature into account. Similar approaches have been used in the past, but they never tested this assumption due to a lack of historical regional data. In our work we use 5-minute measurement data of all transformers of the Dutch transmission grid for the period 2012 until 2019. As there exist a plethora of methods for modelling the national demand for electricity, based on socio-economic data and climate variables, the method presented here focuses only on the spatial distribution of demand. 

Using the data on national demand (ENt) [ENTSO-E], population (Px,t) [NASA GPWv4.11] and temperature (Tx,t) [ERA5], a variety of linear regression models were constructed for the regional demand (Ex,t). Each of these models allows a researcher to disaggregate the national demand time-series to the regional time-series in a simple, but effective manner. Based on our data the model with the highest accuracy out of the sample is of the following form: 

Ex,t = ENt  ( α1 Px,t + α2 Tx,t )

By using this method for the regionalization of electricity demand, a whole new range of research becomes possible. For instance, electricity transmission between regions can be explicitly modelled, enabling the identification of future congestion problems in the network.

How to cite: Stoop, L., Feelders, A., and van den Broek, M.: A validated method for estimating regional electricity demand from national time-series, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15541, https://doi.org/10.5194/egusphere-egu2020-15541, 2020.

EGU2020-16931 | Displays | ERE2.2

Continuous hydrogen production facilitates handling of climatic extreme events in a fully renewable Swedish power system

Christian Mikovits, Johannes Schmidt, and Elisabeth Wetterlund

Hydrogen produced from renewable electricity can play an important role in deep decarbonisation of industry such as steel-production. Steady, full capacity hydrogen production can also be a source of negative balancing capacity to increase flexibility of fully renewable power systems. However, there is a trade-off between attaining economically favorable high-full load hours for the electrolyzer and the provision of system flexibility. To better understand this trade-off, we apply a dispatch model for the Swedish power system with long-term time series 29 years of electricity generation (hydro and wind) and demand at hourly temporal resolution, thus being able to represent climate extreme events.

In our hydrogen demand scenarios for Sweden we limit the hydrogen usage options to two pathways that are currently under development: for hydrotreatment of different bio-based feedstocks in biofuel production, and as use as reductant in fossil-free primary steel-making according to the HYBRIT (Hydrogen Breakthrough Ironmaking Technology) route. We applied three different scenarios that can be seen to represent either different ambition levels for decarbonization, or different time perspectives, and which result in different electrolysis loads on the system:

    • 850 MW electrolyzer capacity, corresponding to 5 TWh·a-1 hydrogen production for biofuels
    • 1700 MW electrolyzer capacity, corresponding to 10 TWh·a-1 hydrogen production for biofuels
    • 3500 MW electrolyzer capacity, corresponding to 10 TWh·a-1 hydrogen production for biofuels and 10.5 TWh·a-1 hydrogen for steel-making.

In comparison to the baseline scenario, more wind power is available in the system, as wind power is scaled accordingly to the average electrolyzer demand.

Results very well present the seasonal differences in demand and how hydro power and partly thermal power are used to balance seasonal differences i.e. extreme events are only observed in the winter months. Also, significant curtailment of wind power capacity is present at some points but less so in the winter months. Extreme events are considerably decreased when increasing electrolyzer capacity, as the electrolyzers are operated flexibly and therefore provide significant positive balancing energy to the system in times of low generation events. In particular, longer events are reduced, creating shorter events to some extent.
Even under the assumption of very low electrolyzer ramping capacities and no dispatch of thermal power for hydrogen production, electrolyzers operate at about 90% of full load and still provide sufficient flexibility to reduce the impact of climatic extreme events on the Swedish power system significantly.

How to cite: Mikovits, C., Schmidt, J., and Wetterlund, E.: Continuous hydrogen production facilitates handling of climatic extreme events in a fully renewable Swedish power system, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16931, https://doi.org/10.5194/egusphere-egu2020-16931, 2020.

EGU2020-18094 | Displays | ERE2.2

Solar futures: a systematic review of long-term global solar photovoltaic adoption scenarios

Marc Jaxa-Rozen and Evelina Trutnevyte

Solar photovoltaic (PV) technology has been the fastest-growing renewable energy technology in recent years. Since 2009, it has in fact experienced the largest capacity growth of any power generation technology, with benchmark levelized costs falling by four-fifths [1]. In addition, the global technical potential of PV largely exceeds global primary energy demand [2]. Nonetheless, PV typically only appears as a relatively marginal option in long-term energy modelling studies and scenarios. These include the mitigation pathways evaluated in the context of the work of the Intergovernmental Panel on Climate Change (IPCC), which rely on integrated assessment models (IAMs) of climate change and have in the past underestimated PV growth as compared to observed rates of adoption [2]. Similarly, global energy projections, such as the International Energy Agency's World Energy Outlook, have been relatively conservative regarding the role of solar PV in long-term energy transitions.

In order to better understand the long-term global role of solar PV as perceived by various modeling communities, this work synthesizes a broad ensemble of scenarios for global PV adoption at the 2050 horizon. This ensemble includes 784 IAM-based scenarios from the IPCC SR15 and AR5 databases, and 82 other systematically selected scenarios published over the 2010-2019 period in the academic and gray literature, such as PV-focused techno-economic analyses and global energy outlooks. The scenarios are analyzed using a descriptive framework which combines scenario indicators (e.g. mitigation policies depicted in a scenario), model indicators (e.g. the representation of technological change in the underlying model), and meta-indicators (e.g. the type of institution which authored a scenario). We extend this scenario framework to include a text-mining approach, using Latent Dirichlet Allocation (LDA) to associate scenarios with different textual perspectives identified in the ensemble, such as energy access or renewable energy transitions. We then use a scenario discovery approach to identify the combinations of indicators which are most strongly associated with different regions of the scenario space.

Preliminary results indicate that the date of publication of a scenario has a predominant influence on projected PV adoption values: scenarios published in the first half of the 2010s thus tend to represent considerably lower PV adoption levels. In parallel, higher projected values are more strongly associated with renewable-focused institutions. Increasing the institutional diversity of scenario ensembles may thus lead to a broader range of considered futures [3].


References
[1] Frankfurt School-UNEP Centre, “Global Trends in Renewable Energy Investment 2019,” Frankfurt, Germany, 2019.
[2] F. Creutzig, P. Agoston, J. C. Goldschmidt, G. Luderer, G. Nemet, and R. C. Pietzcker, “The underestimated potential of solar energy to mitigate climate change,” Nat Energy, vol. 2, no. 9, pp. 1–9, Aug. 2017, doi: 10.1038/nenergy.2017.140.
[3] E. Trutnevyte, W. McDowall, J. Tomei, and I. Keppo, “Energy scenario choices: Insights from a retrospective review of UK energy futures,” Renewable and Sustainable Energy Reviews, vol. 55, pp. 326–337, Mar. 2016, doi: 10.1016/j.rser.2015.10.067.

How to cite: Jaxa-Rozen, M. and Trutnevyte, E.: Solar futures: a systematic review of long-term global solar photovoltaic adoption scenarios, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18094, https://doi.org/10.5194/egusphere-egu2020-18094, 2020.

EGU2020-19913 | Displays | ERE2.2

Modeling of the power generation from wind turbines with high spatial and temporal resolution

Reinhold Lehneis, David Manske, Björn Schinkel, and Daniela Thrän

The share of wind power in the generation of electricity has increased significantly in recent years and, despite its volatility, variable energy from wind turbines has become an essential pillar for the power supply in many countries around the world. To investigate the effects of increasing variable renewables on power grids, the environment or electricity markets, detailed power generation data from wind turbines with high spatial and temporal resolution are often mandatory. The lack of freely accessible feed-in time series, for example due to data protection regulations, makes it necessary to determine the wind power feed-in for a required region and period with the help of numerical simulations. Our contribution demonstrates how such a numerical simulation can be developed using publicly available wind turbine and weather data. Herein, a novel model approach will be presented for the wind-to-power conversion, which utilizes a sixth-order polynomial for the specific power curve of a wind turbine. After such an analytical representation is derived for a certain turbine, its output power can be easily calculated using the wind speed and air temperature at its hub height. For proof of concept and model validation, measured feed-in time series of a geographically and technically known wind turbine are compared with the simulated time series at a high temporal resolution of 10 minutes. In order to determine the power generation for larger regions or an entire country the derived numerical simulation is also carried out for an ensemble of almost 26 thousand onshore wind turbines in Germany with a total capacity of about 44 GW. With this ensemble, first simulation results with municipal and hourly resolution can be presented for an annual period.

How to cite: Lehneis, R., Manske, D., Schinkel, B., and Thrän, D.: Modeling of the power generation from wind turbines with high spatial and temporal resolution, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19913, https://doi.org/10.5194/egusphere-egu2020-19913, 2020.

EGU2020-20428 | Displays | ERE2.2

Integrating energy sectors in a state-resolved energy system model for Australia

Tina Aboumahboub, Robert Brecha, Matthew Gidden, Andreas Geiges, and Himalaya Bir Shrestha

Australia represents an interesting case for energy system transformation modeling.  Wile it currently has a power system dominated by fossil fuels, and specifically with a heavy coal component, there is also vast potential for expansion and use of renewable energy.  Geographically, the country is divided into seven states and territories, two of which have power systems isolated from the rest of the country. Regions have widely differing characteristic energy mixes and resources, ranging from high reliance on brown coal (Victoria), black coal (New South Wales, Queensland), natural gas (Northern Territory, Western Australia) to states that have already moved toward renewable energy-dominant systems (South Australia, Tasmania). Renewable power systems across Australia are experiencing rapid growth, particularly in solar photovoltaics and to a lesser extent with wind power and battery storage. 

In order to better understand the further potential expansion of renewable power systems in Australia, we developed the Australian Energy Modelling System (AUSeMOSYS) based on the open-source OSeMOSYS framework. We apply AUSeMOSYS to investigate cost-optimal transformation pathways towards a carbon-neutral energy system. The model is calibrated carefully to recent past trends in energy generation, including the recent and near-future rapid uptake of renewables in different regions, whether by policy decision or autonomous development.  Beyond the power sector, AUSeMOSYS also provides scenario pathways for the uptake of electric vehicles and hydrogen powered transport, coupled to the power sector with a timeline through 2050. In order to investigate the full extent of renewable energy expansion given Australia’s recognized large renewable energy resource potential, we link selected industrial sectors to the power system model, e.g. steel production, where use of electric generation can further decarbonize Australia’s economy via hydrogen production and use.

In addition to the results showing the potential for large, integrated, cross-sectoral penetration of renewable energy into the Australian energy mix, we investigate modeling sensitivities to key parameters that can affect the uptake and use of renewable energy in the power system. For example, we study sensitivities in the choice of time-step resolution, the availability of trade between states in the National Energy Market (NEM) and the choice of carbon price and carbon cap pathways that can lead to near-zero emissions from the energy system by mid-century.

How to cite: Aboumahboub, T., Brecha, R., Gidden, M., Geiges, A., and Bir Shrestha, H.: Integrating energy sectors in a state-resolved energy system model for Australia , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20428, https://doi.org/10.5194/egusphere-egu2020-20428, 2020.

EGU2020-20568 | Displays | ERE2.2

Flexible energy systems for planning the world’s main copper mines considering geographical conditions

Simon Moreno Leiva, Jannik Haas, Wolfgang Nowak, and Tobias Junne

Energy systems of the future will be highly renewable, but building the required infrastructure will require vast amounts of materials. Particularly, renewable energy technologies are more copper-intensive than conventional ones and the production of this metal is intensive in energy and emissions. Moreover, as mineral resources are being depleted, more energy is required for their extraction, with subsequent increase in environmental impacts. Highly stressed and uncertain water resources only worsen this situation.

In this work, we will first provide a comprehensive review of the limited available energy planning approaches on copper mines, including transferrable learnings from other fields. Our second contribution is to compare the influence of different geographical locations on the optimal design of energy systems to supply the world’s main copper mines. For this, we use a linear energy system optimization model, whose main inputs are hourly time series for solar irradiation and power demand, and projections for energy technology costs and ore grade decline. Our third contribution is to propose a multi-vector energy system with novel demand-side management options, specific to copper production processes, including water demand management, illustrated on a case study in Chile (where mining uses a third of the nationwide electricity).

In the first part, the review, we learned that energy demand models in copper mines have only coarse temporal and operational resolutions, and require major improvements. Also, demand-side management options remain unstudied but could promise large potentials. In general, the models applied in copper energy planning seem overly simplistic when contrasted to available energy decision tools.

For the second part, we observed that in most locations, using local photovoltaic power not only lowers future electricity costs but also compensates for increased energy demand from ore grade decline. Some regions gain a clear competitive advantage due to extremely favorable climatic conditions.

In the third and final part, regarding the demand-side management, we saw how the geography and the spatial design of the mines strongly influence the available options and their performance. Jointly planning flexible water and energy supply seems to be particularly attractive. Also, there is space for smart scheduling of maintenance of the production lines, the hardness of the rock feed, oxygen production, and the hauling (rock transport) fleet.

As an outlook,  we highlight the need for consideration of lifecycle impacts as a design goal, and to further develop demand model’s and their flexibility on the mining side. We expect that implementing these smarter approaches will help secure a cleaner material supply for the global energy transition.

How to cite: Moreno Leiva, S., Haas, J., Nowak, W., and Junne, T.: Flexible energy systems for planning the world’s main copper mines considering geographical conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20568, https://doi.org/10.5194/egusphere-egu2020-20568, 2020.

ERE2.3 – Marine renewable energy; resource characterisation, interactions and impacts

EGU2020-8135 | Displays | ERE2.3

Global wave resource classification and application to marine energy deployments

Iain Fairley, Matthew Lewis, Bryson Robertson, Mark Hemer, Ian Masters, Jose Horrillo-Caraballo, Harshinie Karunarathna, and Dominic Reeve

Understanding and classification of the global wave energy resource is vital to facilitate wave energy converter technology development and global roll-out of this promising renewable energy technology. To date, many wave energy converters have been developed based on Northern European wave climates; these are not representative of wave climates worldwide and may not be the best for large scale energy extraction. Classification of resources will highlight alternative wave resource types that may prove fruitful for deployment of future technologies; equally it will enable existing technology to define regions worthy of site exploration. Therefore k-means clustering is used here to classify the global resource from a data-driven, device agnostic perspective.

Parameters relevant to energy extraction (significant wave height, peak wave period, extreme wave height, spectral and directional properties) were extracted from the ECMWF ERA5 reanalysis dataset and used to split the global resource into 6 classes. Only areas within 3 degrees of land (feasible energy transport to user) were considered. The 6 classes returned by the analysis consisted of: 1) low energy high variability areas in enclosed seas; 2) low energy moderate variability areas in semi-enclosed seas and sheltered ocean coasts; 3) moderate energy areas, largely on eastern oceanic coastlines and influenced by local storm activity; 4) moderate energy areas primarily influenced by long period swell and largely on western oceanic coastlines; 5) higher energy areas, with variable conditions, primarily in the northern hemisphere; 6) highest energy areas, primarily on the tips of continents in the southern hemisphere. Consideration of device power matrices show that existing devices only perform well in classes 5 and 6, despite these areas having limited global coverage, which suggests devices should be developed for lower energy classes.

To refine global roll-out planning for existing devices, based on a request from a wave energy converter developer, a second classification is currently being developed with two additional constraints on the areas tested. These constraints are excluding any areas with a mean wave power of less than 15 kW/m (an often-used value for the lower power limit for commercial viability) and a maintenance constraint whereby wave heights must drop below 3m for a minimum of 48hrs per month. These newer results will be presented at the annual assembly and contrasted with our more device agnostic classification.

How to cite: Fairley, I., Lewis, M., Robertson, B., Hemer, M., Masters, I., Horrillo-Caraballo, J., Karunarathna, H., and Reeve, D.: Global wave resource classification and application to marine energy deployments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8135, https://doi.org/10.5194/egusphere-egu2020-8135, 2020.

EGU2020-8769 | Displays | ERE2.3

Rogue-wave-energy: wave-to-wire mathematical modelling

Onno Bokhove

A novel wave-energy device design [1,2] will be presented based on the following features: (i) an electro-magnetic generator based on cylindrical magnets moving through induction wires around a cylindrical tube, like in the IP wave-buoy, (ii) a convergence in a breakwater to amplify the incoming waves, like in the TapChan device, and (iii) a wave-activated buoy with magnets attached, like in the Berkeley wedge, constrained to move in a slight arc or in a rectilinear manner. Its workings will be demonstrated in a first, operating proof-of-principle. A monolithic mathematical model is established by coupling the three variational principles for the hydro-dynamic wave motion, using the potential-flow approximation, the constrained wave-activated buoy motion, and the electro-magnetic generator together into one grand variational principle. The resistive losses in the electrical circuit and the energy harvested in the (parallel LED) loads are subsequently added to the dynamics. After linearisation of the resulting full 3D nonlinear model around a state of rest and application of the shallow-water approximation, we discretize the linear dynamics in a compatible, i.e. geometrically consistent, manner using a finite-element approach in space and symplectic integrators in time. Preliminary numerical modelling and simple optimization will be shown and these are promising. Finally, further optimisation of the device for different geometries and for a given wave-climate as well as alternative designs will be discussed.

References
[1] O. Bokhove, A. Kalogirou, W. Zweers 2019: From bore-soliton-splash to a new wave-to-wire wave-energy model. Water Waves 1.
[2] O. Bokhove, A. Kalgirou, D. Henry, G. Thomas 2019: A novel rogue-wave-energy device with wave amplification and induction actuator. In: 13th European Wave and Tidal Energy Conference 2019, Napoli, Italy.

How to cite: Bokhove, O.: Rogue-wave-energy: wave-to-wire mathematical modelling , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8769, https://doi.org/10.5194/egusphere-egu2020-8769, 2020.

EGU2020-4058 | Displays | ERE2.3

Dynamical Downscaling of Wind Surface Forcing with Application to the Wave Potential Estimation in the Aegean Sea

Georgios V. Kozyrakis, Katerina Spanoudaki, and Emmanouil A. Varouchakis

Over the last decade, a lot of work has been performed to develop wind-wave potential prediction techniques that, effectively and within realistic time-frames, map the local climatology of a specific region. The combination of local and satellite climatic data, has been used, for good reason, in many wind-related-projects as it is linking mesoscale meteorology, with microclimatic weather phenomena. This way the driving geostrophic winds are effectively taken into account for the estimation of low altitude wind distribution.

Using dynamical downscaling methodology, a nesting technique with 1/3 ratio is applied to downscale the raw computational grid of the satellite input data to a finer 3 x 3 Km results grid. This way, higher computational accuracy is achieved over the investigated regions, thus revealing finer wind scales phenomena. For the computational simulations, two different models have been used in order to generate meteo-climate parameters suitable for sea-wave results calculation: a dynamical downscaling model (at regional scale), and a wave model. The first model performs the downscaling of the satellite meteorological data in higher resolution grids for a wide area of the Aegean Sea. The produced fine grid output drives the later wave model in order to estimate the significant wave height and period over the areas of interest. The produced results will later be used in conjunction with novel geostatistical techniques to estimate the wave energy potential distribution in the Aegean and Ionian Sea.

 

 

Acknowledgements

This project has received funding from the Hellenic Foundation for Research and Innovation (HFRI) and the General Secretariat for Research and Technology (GSRT), under grant agreement No [1237].

How to cite: Kozyrakis, G. V., Spanoudaki, K., and Varouchakis, E. A.: Dynamical Downscaling of Wind Surface Forcing with Application to the Wave Potential Estimation in the Aegean Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4058, https://doi.org/10.5194/egusphere-egu2020-4058, 2020.

EGU2020-1604 | Displays | ERE2.3

Experimental study of the duct-effects of the tidal current turbines in multi-row-staggered layout

Yaling Chen, Binliang Lin, and Jinxi Guo

Tidal turbine array was optimized to increase the power production in order to improve the commercial competitivity of tidal current energy with other forms of energy generation. Due to duct-effects, the power performance of turbines in the staggered layout was better than that of the aligned layout. However, shear layer with enhanced turbulence occurred between the duct zone and isolated wake zone downstream, which had influence on the performance stability and increased the fatigue failure of tidal turbines. The study conducted a series of laboratory experiments to investigate the duct-effects of tidal turbines located in multi-row array with staggered layout. The turbine rotor was represented by porous disc. The flow thrust and time-varying velocity were measured using micro strain gauge and acoustic doppler velometer, respectively. Results showed that the flow was accelerated between turbines with the increment around 20% behind the first row, while the duct-effects were weakened as distance increased downstream. The shear-induced turbulence was enlarged by the duct-effect when it diffused mainly towards individual wake zone at the initial stage. As the turbulence filled the whole individual wake zones, it diffused rapidly to lateral sides and jointed together, and the turbulence intensity across the array wake was significantly higher than that of the free flow. Correspondingly, the performance of turbine rotor located downstream was improved limitedly by the duct-effects, and the stability was reduced clearly. It indicated that the advantage of the duct-effect induced in the staggered layout was limited in the near wake as the lateral interval between two turbine centres was 2 times of rotor diameter.

Keywords: Turbine rotor array; Staggered layout; Duct-effects; Turbine performance; Shear-induced turbulence

How to cite: Chen, Y., Lin, B., and Guo, J.: Experimental study of the duct-effects of the tidal current turbines in multi-row-staggered layout, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1604, https://doi.org/10.5194/egusphere-egu2020-1604, 2020.

EGU2020-2747 | Displays | ERE2.3

The value of tidal-stream energy resource to off-grid communities

Matt Lewis, John Maskell, Daniel Coles, Michael Ridgill, and Simon Neill

Tidal-stream energy research has often focused on the applicability of the resource to large electricity distribution networks, or reducing costs so it can compete with other renewables (such as offshore wind). Here we explore how tidal electricity may be worth the additional cost, as the quality and predictability of the electricity could be advantageous – especially to remote “off-grid” communities and industry.

The regular motion from astronomical forces allows the tide to be predicted far into the future, and therefore idealised scenarios of phasing tidal electricity supply to demand can be explored. A normalised tidal-stream turbine power curve, developed from published data on 15 devices, was developed. Tidal harmonics of a region, based on ocean model output, were used in conjunction with this normalised tidal-stream power curve, and predictions of yield and the timing of electricity supply were made. Such analysis allows the type and number of turbines needed for a specific community requirement, as well as a resource-led tidal turbine optimisation for a region. For example, with a simple M2 tide (12.42hour period) of 2m/s peak flow, which represents mean flow conditions, a rated turbine speed of 1.8m/s gives the highest yield-density of all likely turbine configurations (i.e. calculated from power density and so ignores turbine diameter), and with a 41% Capacity Factor. Furthermore, as tidal current and power predictions can be made, we explore the battery size needed for a given electricity demand timeseries (e.g. baseload, or offshore aquaculture). Our analysis finds tidal-stream energy could be much more useful than other forms of renewable energy to off-grid communities due to the predictability and persistence of the electricity supply. Moreover, our standardised power curve method will facilitate technical tidal energy resource assessment for any region.

How to cite: Lewis, M., Maskell, J., Coles, D., Ridgill, M., and Neill, S.: The value of tidal-stream energy resource to off-grid communities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2747, https://doi.org/10.5194/egusphere-egu2020-2747, 2020.

EGU2020-19231 | Displays | ERE2.3

Bio-optimisation of a tidal channel

Rory O'Hara Murray and Matthew Lewis

Scotland has ambitious decarbonisation and climate change objectives, such as generating 100% of gross annual electricity consumption from renewable sources by 2020. Tidal stream energy is a renewable and predictable source of energy that converts the kinetic energy within tidal currents, into electricity, using a hydrokinetic device such as a horizontal axis turbine. However, economically viable tidal stream development is currently confined to areas of exceptionally high current speeds, and this can severely limit the choice of area. If the speed threshold required for an economically viable tidal site can be lowered then the number of potential sites could increase dramatically.

It is well known that macro-algae (e.g. kelp) grow in perspective tidal energy sites, as they requiring similar water depths and current speeds. Furthermore, kelp is known to grow in dense patches, reaching from the sea-floor to the ocean surface, and can modify tidal current speeds. Indeed, observations have shown that “kelp forests” can locally reduce current speeds by a third (Jackson and Winant, 1983). This local reduction in current speed will cause an increase in speed elsewhere, in order to conserve mass. Therefore, we hypothesise that by adding a kelp forest in the vicinity of a tidal channel, the current speed and tidal stream resource could be increased sufficiently for the site to become economical.

A three dimensional finite volume hydrodynamic model has been used to model an idealised tidal channel. The drag imposed by kelp was theoretically calculated and represented in the model as a sub grid scale momentum sink. The changes to the current speed resulting from this bio-optimisation of the tidal channel were investigated and show that the current speed in the centre of the channel can be increased. Kelp were then added to a previously developed hydrodynamic model of the Pentland Firth and Orkney Waters to investigate how such bio-optimisation could influence an area currently being considered for substantial tidal stream development. The changes on both the areas of suitable tidal stream development and the power yield are investigated.

Acknowledgements

Matthew Lewis wishes to thank Aaron Owen and Ade Fewings at SuperComputingWales, and Fearghal O'Donncha at IBM-research Ireland for fruitful discussions, and the METRIC grant, EP/R034664/1.

References

Jackson, G. A. and Winant, C. D. (1983). Effect of a kelp forest on coastal currents. Continental Shelf Research, 2(1), pp.75-80.

How to cite: O'Hara Murray, R. and Lewis, M.: Bio-optimisation of a tidal channel, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19231, https://doi.org/10.5194/egusphere-egu2020-19231, 2020.

The Rance tidal power station (located on the Brittany coast of Northern France), was opened in 1966 as the world’s first and largest tidal power station, with peak output capacity of 240 Megawatts. It is currently the second world’s largest tidal power installation after the Sihwa Lake Tidal power station (South Korea). The power plant is located at the mouth of a small steep-sided ria, with a maximum perigean spring tidal range of 13.5 m and an average fluvial discharge of 7 m3/s. The dam is 750 m long and the tidal basin measures 22.5 km2. Despite a well-known effect of the plant on the damping of estuarine water levels, little attention has been given to the consequences of the dam in the estuarine environment in terms of hydrodynamics, for instance, the propagation of the tidal wave and tidal currents along the estuary are still little understood. Moreover, net siltation has been reported by several observations, but there is no specific knowledge on the role of the plant on sedimentation. In this study, we analyze the impact of the tidal power station on tidal wave patterns and sediment dynamics in this particular man-engineered system. To this goal, a numerical model based on a two-dimensional depth-averaged approach is implemented to predict the tide propagation and tidal currents along the estuary accounting for the presence of the tidal power station. Three modelling scenarios were performed: the first considering the bathymetry of 1957 (before the plant’s construction), a second scenario considering the bathymetry of 2018 without the presence of the power station and a third scenario considering the bathymetry of 2018 with the power station. Preliminary results showed that, with and without the tidal power station, the upper estuary exhibits a flood dominant behavior, with longer duration of falling water than rising water, and conversely the lower estuary is ebb dominant with shorter duration of falling water than rising water. This analysis also revealed that the tidal power station might switch the flood dominance in the central estuary to ebb dominance. These findings imply a net seaward transport of both coarse and fine sediments in the lower estuary. Therefore, the tidal power station might have a considerable role in modulating the estuarine turbidity maximum and channels’ morphology. Finally, these results are compared with preliminary numerical simulations of suspended sediment transport to further quantify the impact of the tidal power plant on the dynamics of the estuarine turbidity maximum.

How to cite: Rtimi, R., Sottolichio, A., and Tassi, P.: The Rance tidal power station: a preliminary study of its impact on tidal patterns and sediments dynamics in the Rance estuary (France) from 1957 to 2018, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20649, https://doi.org/10.5194/egusphere-egu2020-20649, 2020.

EGU2020-11619 | Displays | ERE2.3

Effects on hydrodynamics and ecological costs of climate change and tidal stream energy extraction in a shelf sea

Michela De Dominicis, Judith Wolf, Dina Sadykova, Beth Scott, Alexander Sadykov, and Rory O’Hara Murray

The aim of this work is to analyse the potential impacts of tidal energy extraction on the marine environment. We wanted to put them in the broader context of the possibly greater and global ecological threat of climate change. Here, we present how very large (hypothetical) tidal stream arrays and a ''business as usual'' future climate scenario can change the hydrodynamics of a seasonally stratified shelf sea, and consequently modify ecosystem habitats and animals’ behaviour.

The Scottish Shelf Model, an unstructured grid three-dimensional ocean model, has been used to reproduce the present and the future state of the NW European continental shelf. While the marine biogeochemical model ERSEM (European Regional Seas Ecosystem Model) has been used to describe the corresponding biogeochemical conditions. Four scenarios have been modelled: present conditions and projected future climate in 2050, each with and without very large scale tidal stream arrays in Scottish Waters (UK). This allows us to evaluate the potential effect of climate change and large scale energy extraction on the hydrodynamics and biogeochemistry. We found that climate change and tidal energy extraction both act in the same direction, in terms of increasing stratification due to warming and reduced mixing, however, the effect of climate change is ten times larger. Additionally, the ecological costs and benefits of these contrasting pressures on mobile predator and prey marine species are evaluated using ecological statistical models.

How to cite: De Dominicis, M., Wolf, J., Sadykova, D., Scott, B., Sadykov, A., and O’Hara Murray, R.: Effects on hydrodynamics and ecological costs of climate change and tidal stream energy extraction in a shelf sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11619, https://doi.org/10.5194/egusphere-egu2020-11619, 2020.

EGU2020-8658 | Displays | ERE2.3

Geological data incorporation into an opportunities model for Irish offshore wind energy to inform engineering considerations and habitat change potential

Jared Peters, Ross O’Connell, Andrew Wheeler, Valerie Cummins, and Jimmy Murphy

The implications of climate change are becoming harder to ignore and highlight the need for increased renewable energy production.  Simultaneously, technological developments like larger turbines and floating foundations are improving our ability to harvest offshore wind energy as a renewable resource.  However, despite having an abundant offshore wind energy resource, Ireland is falling behind on its remit to reduce its carbon emissions as part of the European Union’s targets outlined by the 2030 Climate and Energy Framework.  Reducing this inaction is critically important and improvements to Irish renewable energy planning could also be adapted to other locations.  Here we present spatial data rasters created largely from public datasets that have been designed to improve initial planning and opportunities assessments for Irish offshore wind development.  These rasters include information on surficial sediment types, geomorphology, and slope, which are typically not included in preliminary offshore renewable energy assessments despite their importance to turbine foundation designs, scour protection measures, and cable routes.  Furthermore, these rasters allow fundamental predictions on potential benthic habitat changes to be included into site selection models, which could help avoid economically and/or environmentally costly development decisions.  We examine potential uses for these rasters within a multi-criteria decision analysis and discuss the implications of incorporating such geological data during early investigations. 

How to cite: Peters, J., O’Connell, R., Wheeler, A., Cummins, V., and Murphy, J.: Geological data incorporation into an opportunities model for Irish offshore wind energy to inform engineering considerations and habitat change potential, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8658, https://doi.org/10.5194/egusphere-egu2020-8658, 2020.

EGU2020-21656 | Displays | ERE2.3

Off-Shore wind potential in Cyprus: Towards an integrated representative geospatial database.

Evangelos Akylas, Elias Gravanis, Andreas Nikolaidis, Constantinos F. Panagiotou, Christodoulos Mettas, Phaedon Kyriakidis, and Diofantos Hadjimitsis

Cyprus' energy balance today depends to a large extent on imports of petroleum products for energy production. This has an impact on both the economy and the environment of the island. The contribution of renewable energy sources (RES) in Cyprus, although there is considerable potential, still remains limited. Specifically, renewable energy sources today account for less than 9% of the country's total gross energy consumption.

This paper contributes to the study of the off-shore wind power on the island, focusing on the creation of an integrated geospatial database for the study of wind characteristics on the coasts and offshore of Cyprus using measurements from meteorological stations, data from the European database with horizontal analysis 25x25 km, and 24-hour forecasts from the Open Skiron meteorological model in 5x5 km resolution.

The analysis take advantage of both wind measurement from meteorological stations in coastal Cyprus areas, as well as information on wind values from forecasting models and databases to record an initial reference distribution in space and time.

 

Acknowledgments:

This research is supported by the project  “Cross-Border Cooperation for Implementation of Maritime Spatial Planning” referred as “THAL-CHOR 2” and it is co-funded by the European Regional Development Fund (ERDF) and by national funds of Greece and Cyprus, under the Cooperation Programme “INTERREG V-A Greece-Cyprus 2014-2020”.

How to cite: Akylas, E., Gravanis, E., Nikolaidis, A., Panagiotou, C. F., Mettas, C., Kyriakidis, P., and Hadjimitsis, D.: Off-Shore wind potential in Cyprus: Towards an integrated representative geospatial database., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21656, https://doi.org/10.5194/egusphere-egu2020-21656, 2020.

EGU2020-10178 | Displays | ERE2.3

Numerical Analysis of Floating Offshore Structures Using Overset Method

Sing-Ya Li and Shih-Chun Hsiao

The consciousness of global warming gradually transforms the energy dependency from fossil fuels to renewable energy resources such as waves, wind, solar, and geothermal heat. The flexible deployment range of floating offshore wind turbines makes this technology more popular in the offshore wind energy sector recently. However, this technique is still under development and the fluid-structure interaction (FSI) needs to be further investigated to improve the design of the floating wind turbine platform. Due to the significant evolvement of computer and numerical methods in recent years, computational fluid dynamics (CFD) has been widely applied to solve FSI problems. Grid morphing technique is commonly used to solve FSI problems, however, using this technique to deal with large body displacement problems will lead to large grid deformation and consequently induce numerical instabilities. In this study, overset grid was used to understand the interaction between fluid and floating structures to avoid calculation divergence due to excessive grid deformation. The open-source CFD solver was developed using OpenFOAM for offshore floating structures and the numerical wave tank was developed by integrating the overset grid Navier-Stokes solver, overInterDyMFoam, with a wave generation library in OpenFOAM. The accuracy of the developed model was validated using a series of benchmark tests including heave decay test, roll decay test, and a floating structure subject to different wave conditions. The influences of the overlapping zone properties on the model accuracy were discussed and the results obtained by the current study and those computed by dynamic grid solver were compared. Overall, the computed results presented in this study show good agreement with the results of the benchmark tests.

How to cite: Li, S.-Y. and Hsiao, S.-C.: Numerical Analysis of Floating Offshore Structures Using Overset Method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10178, https://doi.org/10.5194/egusphere-egu2020-10178, 2020.

EGU2020-10179 | Displays | ERE2.3

Experimental and numerical study of the stability of barge-type floating offshore wind turbine platform

Wen-Hsuan Yang, Ray-Yeng Yang, and Tzu-Ching Chang

The global wind energy has developed over 30 years. However, as the offshore wind power installed within 50 to 60 meters of water depth is gradually saturated. Offshore wind power installations are progressively shifting from nearshore to offshore. With the increment of water depth, the difficulties and the cost of the offshore wind power installations are also increased, makes the fixed-bottom type of structures less favorable in deep water areas and accelerate the development of the floating type offshore wind platforms. Floating offshore wind platforms can be classified into main three types: spar buoy, semi-submersible, tension-leg platform (TLP) according to reaching stability. In addition to these types, a barge-type floating platform, a new design concept, can reduce the dynamic motion of the platform by its moon pool. In this study, the hydrodynamic performance of a floating barge platform with a moon pool supports an NREL 5MW wind turbine and with a mooring system at a water depth of 50 meters was investigated. This numerical simulation was applied to analyze the hydrodynamic performance of the platform using ANSYS Aqwa software. Experimental tests in a flat water tank were conducted at National Cheng Kung University, Tainan Hydraulics Laboratory (THL). The model is a 1:64 scaled barge platform and the turbine is scaled down from the NREL 5MW. Three tests of the platform were conducted, including the free decay test, regular wave test, irregular wave test with wind operation and parking. The experimental data was analyzed to get the natural period through the free decay test. The numerical simulation results were compared with the 1:64 scaled experiment to observe the motions and Response Amplitude Operator (RAO) of surge, heave and pitch motions on the barge platform with moon pool. The floating barge platform, designed in this study, will be tested in the open sea to ensure it can withstand - extreme wave conditions such as typhoons.

How to cite: Yang, W.-H., Yang, R.-Y., and Chang, T.-C.: Experimental and numerical study of the stability of barge-type floating offshore wind turbine platform, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10179, https://doi.org/10.5194/egusphere-egu2020-10179, 2020.

In this paper, the commercial software Orcaflex is used to simulate the motion behavior of the OC4 floating platform, and the floater stability and mooring line tension after the mooring system failure. In the time domain analysis, the discussion is divided into three phases—the first phase (before the tether failure), the second phase (before the tether failure, before reaching the new steady-state), and the third phase (after reaching the new steady-state). The motion characteristics and tension values at different stages were observed. In this study, only a 50-year return period wave condition is used as an input condition and simulating 11 different incident wind and wave directions. The numerical results are presented in the trajectory map and the table. About the tension of the mooring line, after the mooring system fails, it is notable that the mooring line tension will first decrease and then increase slightly above the initial tension value. In other words, the mooring system may survive after the failure of one mooring line and got a new balance of it. However, the tension amplitude will be higher than the first stage in the new balance and it will likely increase the risk of mooring line fatigue.

How to cite: Chuang, T.-C., Yang, W.-H., Chen, Y.-H., and Yang, R.-Y.: The Dynamic Motion of the OC4 Floating Turbine with Different Incident Wave and Wind Directions in a Mooring System Failure Condition in Numerical Model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12098, https://doi.org/10.5194/egusphere-egu2020-12098, 2020.

ERE2.6 – Exploration, utilization and monitoring of conventional and unconventional geothermal resources

EGU2020-19239 | Displays | ERE2.6 | Highlight

Assessing the Carbon Intensity of Low-Enthalpy Deep Geothermal Heat

Alistair McCay, Jen Roberts, and Michael Feliks

Decarbonising heating presents a significant societal challenge. Deep geothermal energy is widely recognised as a source of low carbon heat. However, to date there has been no assessment of the carbon intensity of heat from low-enthalpy deep geothermal as previous studies have focussed on geothermal power or higher enthalpy heat. Further, there is currently no established method for assessing the CO2 emissions reduction from implementing a deep geothermal heating scheme.

To address these gaps, we performed a life cycle assessment of greenhouse gas emissions relating to a typical deep geothermal heat system to (i) calculate the carbon intensity of geothermal heat (ii) identify the factors that most affect these values (iii) consider the carbon abated if geothermal heat substitutes conventional heating sources and (iv) set a benchmark methodology that future projects can adapt and apply to assess and enhance the carbon emissions reduction offered by geothermal heat development in the UK and internationally.

In the absence of an established deep geothermal heat system in the UK, to inform our work we adopted parameters from a feasibility study for a potential geothermal heat system in Banchory, Scotland. The Banchory project aimed to deliver heat to a network sourced from 2-3 km deep in a radiothermal granite where temperatures were predicted to be 70-90 °C. We assumed a 30 year project lifetime and that the heat system operation was powered by the UK electricity grid which was decarbonising over this period.

Our analysis found that the carbon intensity of deep geothermal heat is 9.7 - 14.0 kg(CO2e)/MWhth. This is ~5% of the value for natural gas heating. The carbon intensity is sensitive to several factors, and so the carbon intensity of deep geothermal heat could be reduced further by: replacing diesel fuelled drilling apparatus with natural gas or electricity powered hardware; decarbonise the power grid more rapidly than forecast; or substitute mains power with local renewable electricity to power pumps – or decarbonising the electricity grid faster or deeper; source lower carbon steel and cement; design projects to minimise land use change emissions.

Overall, our study provides quantitative evidence that deep geothermal systems can produce long term very low carbon heat that is compatible with net-zero, even for low enthalpy geothermal resources.

How to cite: McCay, A., Roberts, J., and Feliks, M.: Assessing the Carbon Intensity of Low-Enthalpy Deep Geothermal Heat, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19239, https://doi.org/10.5194/egusphere-egu2020-19239, 2020.

EGU2020-10482 | Displays | ERE2.6

How well do we know our models?

Denise Degen, Karen Veroy, Mauro Cacace, Magdalena Scheck-Wenderoth, and Florian Wellmann

In Geosciences, we face the challenge of characterizing uncertainties to provide reliable predictions of the earth surface to allow, for instance, a sustainable and renewable energy management. In order, to address the uncertainties we need a good understanding of our geological models and their associated subsurface processes.

Therefore, the essential pre-step for uncertainty analyses are sensitivity studies. Sensitivity studies aim at determining the most influencing model parameters. Hence, we require them to significantly reduce the parameter space to avoid unfeasibly large compute times.

We distinguish two types of sensitivity analyses: local and global studies. In contrast, to the local sensitivity study, the global one accounts for parameter correlations. That is the reason, why we employ in this work a global sensitivity study. Unfortunately, global sensitivity studies have the disadvantage that they are computationally extremely demanding. Hence, they are prohibitive even for state-of-the-art finite element simulations.

For this reason, we construct a surrogate model by employing the reduced basis method. The reduced basis method is a model order reduction technique that aims at significantly reducing the spatial and temporal degrees of freedom of, for instance, finite element solves. In contrast to other surrogate models, we obtain a surrogate model that preserves the physics and is not restricted to the observation space. As we will show, the reduced basis method leads to a speed-up of five to six orders of magnitude with respect to our original problem while retaining an accuracy higher than the measurement accuracy.

In this work, we elaborate on the advantages of global sensitivity studies in comparison to local ones. We use several case studies, from large-scale European sedimentary basins to demonstrate how the global sensitivity studies are used to learn about the influence of transient, such as paleoclimate effects, and stationary effects. We also demonstrate how the results can be used in further analyses, such as deterministic and stochastic model calibrations. Furthermore, we show how we can use the analyses to learn about the subsurface processes and to identify model short comes.

How to cite: Degen, D., Veroy, K., Cacace, M., Scheck-Wenderoth, M., and Wellmann, F.: How well do we know our models?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10482, https://doi.org/10.5194/egusphere-egu2020-10482, 2020.

EGU2020-16260 | Displays | ERE2.6

Monitoring deep fractured reservoirs with ambient noise correlation: importance of acousto-elastic effects

Jérôme Azzola, Jean Schmittbuhl, Dimitri Zigone, Olivier Lengliné, and Frédéric Masson

An emerging technique for a continuous and low cost geophysical monitoring of deep reservoirs like Enhanced Geothermal Systems (EGS) is based on ambient seismic noise correlation and in particular Coda Wave Interferometry (CWI) from temporal stacks of ambient noise cross-correlation functions (or ANCCFs). We present here a forward numerical model simulating the propagation of scattered waves through a reservoir during its deformation, including non-linear acousto-elastic effects. Our approach is based on the case study of the Rittershoffen geothermal reservoir (France). We validate the numerical model by reproducing seasonal variations of the relative changes in seismic velocity observed from ANCCFs and provide a physical interpretation of this seismic signal. We extend our modelling to the in-situ deformation of the reservoir by considering either a hydraulic pressure increase or an aseismic shear of an embedded fault. The sensitivity of the scattered waves to small strain perturbations enables to detect small travel time changes as dt/t ~ 10-5, which opens perspectives for the application of ambient noise based techniques to the continuous monitoring of local mechanisms in deep geothermal reservoirs.

How to cite: Azzola, J., Schmittbuhl, J., Zigone, D., Lengliné, O., and Masson, F.: Monitoring deep fractured reservoirs with ambient noise correlation: importance of acousto-elastic effects, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16260, https://doi.org/10.5194/egusphere-egu2020-16260, 2020.

In recent years several deep geothermal energy projects have been forced to close following the occurrence of large seismic events associated with the stimulation of the surrounding bedrock. In 2018, an enhanced geothermal system (EGS) experiment performed in Helsinki, Finland concluded with no seismicity exceeding the threshold magnitude and thus provides an intriguing showcase for future stimulation experiments in similar environments. During the 49 days of the experiment, the five-stage injection of ~18,000 cubic meters water stimulated many thousands of earthquakes. Like in all previous stimulation cases the earthquake data constitute the primary source for the assessment of the scientific and operational aspects of the reservoir response. Here we apply ambient noise based monitoring and imaging techniques to data collected by 100 short period three-component stations that were organized in three large arrays consisting of nominally 25 stations, in addition to three small four-station arrays, and 10 single stations, during a 100 day period. We compute daily nine-component noise correlations between all stations pairs except for the intra-array pairs in a frequency range between 0.5 and 10 Hz. We measure waveform delays within our correlation functions as a function of frequency and lag time using the Continuous Wavelet Transform. We then invert these observations using a Markov chain Monte Carlo method to obtain the temporal variation in seismic velocity dv/v during the injection. By exploiting the variable spatial sensitivities of the surface- and body-wave components at different coda-wave lapse times and frequencies, we are able to image the medium response to the stimulation in both time and space. We compare the estimated seismic velocity variations to other observations such as H2/V2, as well as dv/v observations obtained from collocated borehole data. Importantly, we also compare the observed medium response to seismicity and pumping parameters. Our results suggest that we are able to resolve medium changes that are not solely associated with the induced earthquakes, but also potential signatures of fluid content or pressure changes in the bedrock. The combined observations of seismicity, pumping parameters and dv/v changes collected in this experiment can further advance passive monitoring techniques in the context of enhanced geothermal systems, and facilitate a more comprehensive analysis of fluid-rock interactions that may occur aseismically.

How to cite: Taylor, G. and Hillers, G.: Passive monitoring and 3D imaging of the bedrock response to the 2018 Espoo/Helsinki geothermal stimulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18827, https://doi.org/10.5194/egusphere-egu2020-18827, 2020.

EGU2020-8696 | Displays | ERE2.6

Geothermal energy in Pyhäsalmi mine, Finland: performance evaluation of heat collector types

Annu Martinkauppi, Kaiu Piipponen, and Lasse Ahonen

Finland is a part of a low-temperature geothermal regime of Fennoscandian Shield. The need for heating energy is high and ground source heat pumps (GSHP) are common in heating of single houses. Shallow ground source heat can be effectively utilized using a closed collector loop with non-freezing heat carrier fluid operating at the temperature range of about -5 to +5°C. The system is economically feasible, because the average target temperature in heating of well-isolated houses is low. District heating requires high output temperatures (in Finland nowadays up to 110°C), implying that a heat pump must receive the ground temperatures of at least about 20°C. Heat collectors in porous, permeable sedimentary rocks may be based on an open circulation loop between two or more boreholes, whereas in Finland single deep boreholes equipped with a heat collector are mainly considered. A borehole heat exchanger (BHE) in deep and warm bedrock, like in decommissioned underground mines offers great temperature benefits in producing more energy than BHE placed on the ground surface.

The Pyhäsalmi mine in northern Ostrobothnia, Finland, is a 1 440 meter deep underground zinc and copper mine that will be decommissioned in a near future. In the Pyhäsalmi Energy Mine project funded by European Regional Development Fund (ERDF) we examined the heat transfer properties of heat collector types installed in the borehole at the bottom of the mine. The Precambrian crystalline bedrock, consisting of granitoids, migmatites, gneisses and schists typically has low geothermal gradient (10 – 20 K/km), but thermal conductivity is rather high (2.5 – 3.5 Wm-1K-1). Thus, the temperature at the depth of 1 440 m is about +20°C. We compared the performance of different collector types in the underground mine environment: coaxial open-loop collector with and without insulation and u-tube collector, as well as different borehole radii to optimize geothermal energy production. Also, we studied the effect of the bedrock temperature (5 – 50°C) on the performance of the BHE.

The heat exchange modelling was carried out with COMSOL Multiphysics®. The modelled physics included conductive heat transfer in bedrock and different collector types, and conductive-convective heat transfer in heat carrier fluid. The models were used to simulate heat transfer from bedrock to the heat circulation loop up to 100 years circulating water (feeding temperature +6°C) in the loop.

The results indicate that a single 300 meter deep energy well placed at the bottom of the mine can be dimensioned to produce water of approximately 12°C with twelve kilowatts power. Further increase in output temperature requires deeper boreholes or serial coupling of two boreholes, allowing heat production at the temperature range of 70 – 90 °C by means of heat pumps. Compared with the conventional shallow geothermal energy solutions, the geothermal potential of the underground mine is several times higher due to higher bedrock temperature. An insulated open-loop coaxial collector is better than a coaxial collector without an insulation or a typical u-tube collector.

How to cite: Martinkauppi, A., Piipponen, K., and Ahonen, L.: Geothermal energy in Pyhäsalmi mine, Finland: performance evaluation of heat collector types, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8696, https://doi.org/10.5194/egusphere-egu2020-8696, 2020.

EGU2020-22434 | Displays | ERE2.6

Interactions between a calcium scaling inhibitor, geothermal fluids, and microorganisms – Results of in situ monitoring in the molasse basin and laboratory experiments

Christoph Otten, Beate Schulz, Sebastian Teitz, Florian Eichinger, Andrea Seibt, Dietmar Kuhn, and Hilke Würdemann

The economic and technical efficiency of geothermal plants is often impaired by corrosion, scaling and biological fouling. In Germany, the highly saline fluid of the North German Basin is known to cause severe corrosion. Meanwhile geothermal plants in the southern Molasse Basin, one of the most extensively exploited geothermal regions in Germany, are troubled by carbonate scaling. One possible solution is the employment of a scale inhibitor. A novel scaling inhibitor is evaluated in field- and laboratory tests. This inhibitor consists of a polysaccharide backbone structure and branches of polyacrylic- and maleic acid copolymer.

The laboratory tests with different scaling inhibitor concentrations were designed to observe the biodegradation of the scaling inhibitor in an anaerobic environment similar to the conditions found in heat exchangers of geothermal plants. The concentration of inhibitor was quantified by UV/VIS and liquid chromatography (LC). Molecular biological techniques (PCR, DGGE, Microbiome analysis) were used to characterize the biocenosis on metal surfaces and in fluids of the experiments.

During the experiment the concentration of inhibitor decreased up to  3 % of the initial concentration. The formation of methane and acetate was observed which indicates a biological degradation by acetoclastic methanogenesis. Hydrogen formation was observed in setups containing steel coupons. This implies that hydrogen is primarily formed by corrosion processes and in tests with active microorganisms hydrogen was consumed completely. Various fermentative bacteria classified as Clostridia and Firmicutes as well as methanogenic archaea were identified. In some experiments sulfate reducing bacteria were found. Those are well known to catalyze corrosion processes.

Results of field experiments in a bypass system as well as microbiological monitoring of the inhibitor application in geothermal plant located in the molasse basin will be presented.

How to cite: Otten, C., Schulz, B., Teitz, S., Eichinger, F., Seibt, A., Kuhn, D., and Würdemann, H.: Interactions between a calcium scaling inhibitor, geothermal fluids, and microorganisms – Results of in situ monitoring in the molasse basin and laboratory experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22434, https://doi.org/10.5194/egusphere-egu2020-22434, 2020.

EGU2020-9104 | Displays | ERE2.6

Hemispherical underground borehole heat exchanger field as a source of geothermal energy

Kimmo Korhonen, Jaakko Hietava, and Lasse Ahonen

Finland is located between the 60th and 70th northern parallels and is characterized by continental subarctic climate. Due to climatic conditions, ground surface temperatures are low in Finland. The long-term average annual ground surface temperature ranges from 0.5 to 7.6 °C. Decommissioned mines offer a way to tap into larger geothermal resources by allowing access to deep underground where the temperature regime is more beneficial for heat extraction than in the shallow ground. The Energy Mine project was initiated to investigate how the Pyhäsalmi deep mine could be utilized to tap into the deeper geothermal resources of the Finnish bedrock.

The depth level of the deepest mine tunnel in the Pyhäsalmi mine is 1,440 m. We took this tunnel as the starting point for our study since it offers access to the largest geothermal resources that are accessible from the mine. We modelled the thermal performance of borehole heat exchanger (BHE) fields constructed by drilling the boreholes from a single site in different azimuth and tilt angles so that the resulting BHE fields took the form of a lower hemisphere. The borehole length was 300 m. The collector was coaxial open-loop with an insulated pipe. Bedrock temperatures within the depth range of the BHE fields ranged from 21 to 25 °C. Finite element models were constructed to simulate the operation of various configurations of hemispherical BHE fields. In all simulations, the temperature of the heat carrier fluid fed to the inlets of the BHEs was kept at 6 °C during the 100 simulated years.

The results indicate that it would require at least 145 BHEs for a hemispherical BHE field to sustain at least 1 MW of heating power from the bedrock for 25 years. Such a field would produce 300 GWh of heating energy during the first 25 years. This amount can be increased by adding boreholes to the field. However, at some point, adding BHEs no longer increases the amount of thermal energy that can be extracted from a hemispherical BHE field. The maximum amount of extractable energy is somewhere around 1.2 TWh which is the estimated heat content of a hemispherical volume of bedrock at the tunnel depth.

The hemispherical design is not the most optimal BHE field design with respect to thermal performance because the distances between BHEs become very small at the drilling site. However, the spatial restrictions imposed by mine tunnels do not allow much leeway in BHE field design. Another possibility is to construct a BHE field along a mine tunnel. But even in this case the BHEs would need to be drilled in a fan-like fashion at several drilling sites along the tunnel length. The hemispherical design is advantageous with respect to drilling and piping compared to a BHE field that is constructed along the length of a mine tunnel.

How to cite: Korhonen, K., Hietava, J., and Ahonen, L.: Hemispherical underground borehole heat exchanger field as a source of geothermal energy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9104, https://doi.org/10.5194/egusphere-egu2020-9104, 2020.

EGU2020-3918 | Displays | ERE2.6

Exhumed vs active geothermal systems: faults controlling ore deposits in Las Minas area as a key for the deep exploration in the Los Humeros geothermal field (Mexico)

Domenico Liotta, Alessandro Agostini, Eivind Bastesen, Caterina Bianco, Chiara Boschi, Eleonora Braschi, Andrea Brogi, Alfredo Caggianelli, Victor Hugo Garduno, Eduardo Gonzalez Partida, Guia Morelli, Emmanuel Olvera-Garcia, Giovanni Ruggieri, Anita Torabi, Gennaro Ventruti, Walter Wheeler, and Martina Zucchi

The investigation of the deep geothermal systems is a challenging task in active geothermal systems. In order to decrease the mining risk, the study of the analogue exhumed systems sheds light on the relationships between fluid circulation and geological structures through the analyses of faults and ore deposits distributions. In the Las Minas area (Central Mexico), ore deposits are quite diffuse at the boundary between crystalline and sedimentary rocks and in fault zones. This is a consequence of the interaction between cooling of Miocene felsic magmas, hydrothermal fluids and coeval fault activity. We investigated the role of the faults in channeling the hydrothermal fluids by fieldwork and analysis of fractures at outcrops. The field mapping was carried out at 1:10000 scale (60 km2). When possible, kinematic data on recent fault planes influencing the permeability and geothermal fluid paths were collected. This includes information on the main structural trends and the orientation of the intermediate kinematic axis.The evolution and origin of the hydrothermal fluids circulating in the exhumed geothermal system of Las Minas area (Central Mexico) were investigated by i) structural and minero-petrographic studies and, ii) fluid inclusion and isotope analyses carried out on skarn and hydrothermal alteration minerals.Two families of faults have been recognized, NNW-SSE and SW-NE oriented, respectively. The SW-NE trending faults often controlled the emplacement of dykes, indicating that the magmatic fluid was channeled and driven by the faults induced permeability. Their activity is at least encompassed between Miocene and Quaternary. The kinematic relation between these two fault systems could be explained in a extensional framework, assuming that the NNW-SSE fault system acted as transfer faults. Fluid inclusions recorded the circulation of: 1) high-temperature (up to 650°C), high-salinity (up to 60 wt.% NaCl equiv.) fluid of magmatic origin; 2) high-temperature (470-650°C) aqueous-carbonic fluid produced during fluid-rock interaction with carbonate basement rocks and 3) relatively low-salinity (up to 2 wt.% NaCl equiv.) fluid of meteoric origin. A general evolution from high- to low-temperature fluid circulation characterized the geothermal system.

How to cite: Liotta, D., Agostini, A., Bastesen, E., Bianco, C., Boschi, C., Braschi, E., Brogi, A., Caggianelli, A., Garduno, V. H., Gonzalez Partida, E., Morelli, G., Olvera-Garcia, E., Ruggieri, G., Torabi, A., Ventruti, G., Wheeler, W., and Zucchi, M.: Exhumed vs active geothermal systems: faults controlling ore deposits in Las Minas area as a key for the deep exploration in the Los Humeros geothermal field (Mexico), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3918, https://doi.org/10.5194/egusphere-egu2020-3918, 2020.

EGU2020-10764 | Displays | ERE2.6

Revisiting Toba Caldera: an insight from regional magnetotelluric data

Lukman Sutrisno, Fred Beekman, Yunus Daud, and Jan Diederik Van Wees

Regional magnetotelluric (MT) survey had been conducted to image resistivity structures beneath Toba Caldera, Indonesia. A crustal-scale 2D inversion model is generated from ten MT stations with extended recording time, deployed along NE-SW regional line to cross perpendicularly both the Caldera and the nearby regional strike-slip fault system, the Sumatran Fault. High resistivity background is likely related to Palaeozoic rocks which is basement of the Tertiary sediments and the Quaternary volcanics. The most noticeable conductive anomaly is located between 10-20 km deep, interpreted as the main magma reservoir beneath the region. An intermediate, less than 10 km-deep, less conductive anomaly beneath the Caldera is interpreted as shallow magma chamber affected by the last major eruption. Shallow, less than 2 km-deep conductive layers are associated either with hydrothermal clay cap beneath the Caldera, or sedimentary formations of the nearby basins. Other conductive anomaly is spatially associated with the Sumatran Fault which located 15 km away from the Caldera. Parameter plots of some stations are consistent with the orientation of basement structures, while the others may be affected by more complex caldera structures. A conceptual model of magma plumbing system beneath the Caldera is then interpreted from the combination of regional resistivity structures, surface geology, and available seismic tomography.

How to cite: Sutrisno, L., Beekman, F., Daud, Y., and Van Wees, J. D.: Revisiting Toba Caldera: an insight from regional magnetotelluric data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10764, https://doi.org/10.5194/egusphere-egu2020-10764, 2020.

EGU2020-4246 | Displays | ERE2.6

The in-situ stress state of the Rhine-Ruhr region and its implications for the geothermal energy utilization

Michal Kruszewski, Giordano Montegrossi, Tobias Backers, and Erik Saenger

The Rhine-Ruhr region is one of the largest metropolitan areas in Europe, with more than 10 million inhabitants, located in western Germany. The region is defined by the rich coal-bearing layers from the upper Carboniferous period, extracted as early as the 13th century and belonging to the sub-Variscan Trough. In 2018, after more than 700 years of exploration, the last black coal mine was closed in the area. One of the most promising re-uses of the abandoned coal mines is the exploitation of geothermal energy sources. Additionally, to the geothermal energy extracted from existing mines, potential deep geothermal reservoirs within the Rhine-Ruhr, may exist at depths between 4.5 and 6 km, where Devonian limestones were found. Based on the available temperature profiles from deep exploration wells in the area, geothermal gradient amounts to 36.8oC/km and results in reservoir temperatures between 170oC and 220oC, which will enable not only heat but even electricity production. This study provides a comprehensive investigation of the full in-situ stress state tensor with its anisotropy and presents crucial physical formation and natural fracture properties. The data for this investigation was acquired from the extensive borehole logging and geomechanical campaigns carried out in deep coal exploration wells throughout the 1980s as well as from the recent shallow geothermal research wells. Acquired data allowed assessing critically-stressed, i.e. hydraulically active, fractures undergoing shear displacement, being primarily responsible for the future geothermal reservoir permeability. Extensive sets of microseismic, subsidence and drilling data were used to confirm the results of the analysis. Additionally, wellbore stability analysis and potential drill paths for the future medium-to-deep geothermal wells in the region were assessed. This study is a part of the 3D-RuhrMarie project, which aims to assess the intrinsic seismic risk within the Rhine-Ruhr region to promote safer and economically more efficient exploration and exploitation of the future geothermal resources.

How to cite: Kruszewski, M., Montegrossi, G., Backers, T., and Saenger, E.: The in-situ stress state of the Rhine-Ruhr region and its implications for the geothermal energy utilization, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4246, https://doi.org/10.5194/egusphere-egu2020-4246, 2020.

EGU2020-19662 | Displays | ERE2.6

The geothermal potential of sedimentary basins – case study for Berlin, Germany

Judith Bott, Maximilian Frick, Nora Koltzer, Mauro Cacace, Björn Lewerenz, Michael Schneider, and Magdalena Scheck-Wenderoth

In this case study a method to estimate the geothermal potential is presented for the capital city of Berlin, Germany. Therefore, it is essential to know the temperature distribution in the subsurface which has been studied intensively in the past.
Building on this knowledge, newly available subsurface temperature predictions have been used along with updated geometries and geophysical properties as input data for the application case of hydrothermal doublets and their comparison to earlier realizations. This shows how considering more complex geometries, boundary conditions and processes in numerical 3D thermohydraulic simulations leads to significant changes in the predicted geothermal potential and the associated controlling factors. The model area is part of the Northeast German Basin which consists of a thick sequence (up to 10 km) of differently consolidated sedimentary deposits. This sequence is made up of alternating aquifers and aquitards, wherein several encompass promising targets for different geothermal application scenarios. Namely these include the Jurassic, Middle Buntsandstein and the Sedimentary Rotliegend aquifers. The former two of these reservoirs depict a complex geometry (mainly due to deeper salt movements) leading to a wide range of predicted temperatures, while the latter (situated below the salt) has a more homogenous topography and temperature distribution. This is also connected to the efficacy of different heat transport processes at different depths.
The predicted heating power is therefore also distributed heterogeneously and reaches maxima as large as 1.25 MWth for the Jurassic, 10 MWth for the Middle Buntsandstein and 2.2 MWth for the Sedimentary Rotliegend. The models further show that the geothermal potential (or the heating power) of a hydrothermal doublet is controlled by more than merely the reservoir temperature but also the producible mass flux, which in turn depends highly on the reservoir transmissivity. Due to the high variability of predicted geothermal potentials, different utilization scenarios should be investigated in future studies, such as aquifer thermal energy storage or low enthalpy geothermal utilizations.

How to cite: Bott, J., Frick, M., Koltzer, N., Cacace, M., Lewerenz, B., Schneider, M., and Scheck-Wenderoth, M.: The geothermal potential of sedimentary basins – case study for Berlin, Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19662, https://doi.org/10.5194/egusphere-egu2020-19662, 2020.

EGU2020-20712 | Displays | ERE2.6

Facies, porosity and permeability prediction and 3-D geological static model in the Middle Jurassic geothermal reservoir of the Paris Basin by integration of well logs and geostatistical modeling

Hadrien Thomas, Benjamin Brigaud, Hermann Zeyen, Thomas Blaise, Simon Andrieu, Maxime Catinat, Mélanie Davaux, and Miklos Antics

In France, heating networks are largely dependent on fossil fuels (42%), and deep geothermal energy represents less than 5% of the energy mix of heating networks. Deployment of geothermal energy in large cities is limited by a geological risk, difficult to predict. This risk constitutes an obstacle to the future development of geothermal energy in the Ile-de-France region. The aim of this work is to develop a predictive 3D reservoir model in terms of stratigraphic geometries, facies, porosity, permeability and temperature at a given location in Ile-de-France. We focus on the main geothermal reservoirs in the area: the Middle Jurassic limestones. In order to create this 3D model, 80 wells (630 logs), drilled over the last 60 years, were studied over an area of 800 km2. The first phase of this study consisted in digitizing the old well data, particularly log data on 80 wells (GR, Sonic, resistivity) and adding all recent wells (with neutron porosity and NMR logs). We also compiled from the drilling reports 694  porosity (phi) – permeability (k) values previously measured on cores from plugs, and we imported them into the geomodeller Petrel®. Two reference wells with cores of the reservoir were studied in detail from a sedimentological and stratigraphic point of view in order to link sedimentary facies, logs and phi-k in a well-defined sedimentological framework. We also digitized temperature in 40 wells. The sequence stratigraphy framework allows to define 11 3rd order stratigraphic sequences from the Bajocian (jason Zone) to the Middle Callovian (zigzag Zone). Twelve surfaces from Bj5 to Ca3 corresponding to 3rd order Maximum Regressive Surfaces (MRS) allow to correlate all wells and to define stratigraphic geometries. A total of 10 facies are grouped into 4 facies associations (1) marls of lower offshore (facies association FA1), (2) marl-limestone alternations of upper offshore (FA2), (3) oolitic grainstones of the shoreface (FA3) and (4) lagoon micritic limestones (FA4). These facies associations were coded in all wells according to the log depths. The best reservoir is mainly located in the oolitic and bioclastic grainstones (FA3) with average porosity of 12% and permeability of 130 mD. The lagoon micritic facies also presents interesting properties with average porosity of 8.2% and permeability of 46 mD. The model has been meshed into 6.5 million of cells split on 64 vertical cell layers of 150 m x150 m x about 5 m (length ×width ×height) each bearing specific property information (facies, porosity, permeability). The final model shows a high variability of the facies distribution over the 11 depositional sequences. The maximum thickness of the oolitic reservoir is about 50 m in the western part of the study area between surface Bt2 and Bt4. By combining the isopach map of oolitic facies between surface Bt2 and Bt4 with porosity above 10%, permeability of more than 100 mD and temperature larger than 60°C, we locate areas of interest for geothermal development in the Paris Basin.

How to cite: Thomas, H., Brigaud, B., Zeyen, H., Blaise, T., Andrieu, S., Catinat, M., Davaux, M., and Antics, M.: Facies, porosity and permeability prediction and 3-D geological static model in the Middle Jurassic geothermal reservoir of the Paris Basin by integration of well logs and geostatistical modeling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20712, https://doi.org/10.5194/egusphere-egu2020-20712, 2020.

CO2 Capture and Storage (CCS) is regarded as one of the most effective measures for the mitigation of the unfavourable effects of anthropogenic CO2 emissions on climate change. The implementation of CCS in geothermal fields which are considered as natural analogues for CO2 storage sites, can contribute to the reduction of CO2 emissions as well as increasing the energy production within the context of Enhanced Geothermal Systems (EGS). Given that experimental studies of CCS have certain limitations regarding the time span and reservoir conditions, the geochemical modelling studies are highly important. The geochemical modelling studies require the use of “input data” including i) modal mineralogy of the reservoir rocks and ii) hydrogeochemistry of the reservoir fluid, the variations in the former (both type and amount) particularly affecting the modelling results.

This study is concerned with a preliminary lithogeochemical characterization of the reservoir levels of two geothermal fields (Akköy-Denizli and Edremit-Balıkesir) from western Anatolia, aiming to establish an input database for a prospective geochemical modelling in EGS. In this regard, drill cuttings belonging to the reservoir levels of the relevant fields are examined both macroscopically and microscopically, followed by the laboratory analyses of the samples using XRF (X-Ray Fluorescence), XRD (X-Ray Diffraction), and confocal Raman Spectroscopy techniques. The results obtained from the analyses are evaluated for the identification and quantification of the present minerals. Since the fields Akköy and Edremit have different reservoir lithologies (schist-calcschist-marble and agglomerate units, respectively), the results provide a means of comparison for the effect of mineralogical changes in possible CO2 addition to the systems.

How to cite: Elidemir, S. and Güleç, N.: Lithogeochemical Characterization of Akkoy and Edremit Geothermal Fields as Prospective CO2 Storage Sites: A Preliminary Study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-452, https://doi.org/10.5194/egusphere-egu2020-452, 2020.

EGU2020-9769 | Displays | ERE2.6

Shallow Geothermal Resources Assessment of the Brussels Region: Exploration, 3D Geological Model, Geothermal Potential Mapping and Challenges Related

Estelle Petitclerc, Pierre Gerard, Xavier Devleeschouwer, Bertrand François, Marijke Huysmans, Mathieu Agniel, Valériane Gigot, Louis Gaudaré, Gust Van Lysbetten, and Christian Burlet

In 2015, a legal framework was implemented in the Brussels-Capital Region (BCR) where passive construction has been mandatory with an obliged heat demand not exceeding 15 kWh/m2. Since 2015, the interest in installing shallow geothermal systems has significantly increased. However, limited knowledge of ground conditions, lack of public awareness and the urban nature of the Brussels area restrict the development of shallow geothermal systems despite the high potential of this technique in the RBC. The BRUGEO project aims to facilitate accessibility and the efficient use of shallow geothermal energy in the BCR specifically for commercial and residential sectors. Thanks to Brussels ERDF (European Regional Development Fund) funding a consortium of all major actors in geothermal energy were brought together (ULB, Brussels Environment, BBRI, VUB, and GSB). During the  four years project (2016-2020), specific actions promoting the geothermal potential were addressed: 1- Collect existing data related to the knowledge on Brussels subsurface (geological, hydrogeological, and geothermal data) and consolidate them in a single database; 2- Conduct new laboratory and field tests in order to complete geological analyses and to assess geothermal parameters; 3- Map the geothermal potential for open and closed systems. The Geological Survey of Belgium (GSB) has created, during the last 7 years, a GIS based 2D-3D geological model of the BCR underground. 9266 drillings and geotechnical data collected in and around the BCR have been used to create the Brustrati3D model generating interpolated top and base surfaces for 19 geological layers representing the whole lithostratigraphic sequence from Quaternary to the Paleozoic basement. An important exploration phase was included in the first two years of the BRUGEO project to acquire new data improving the geological and hydrogeological knowledge of BCR. Several in-situ parameters are measured by e.g. new piezometers implementation and monitoring, pumping tests, cores sampling, logging and enhanced thermal response tests (eTRT). These measurements are implemented as far as possible on future private projects by a win-win approach. The idea is to be grafted on existing projects to increase the data acquisition and to avoid purely exploratory drilling that are expensive and not used later for any geothermal exploitation. So far, the BRUGEO consortium has also conducted three exploration drillings to assess the lithology, the structure, the groundwater flows, and geophysical properties of the Cambrian basement (Brabant Massif). In parallel, laboratory measurements are achieved to characterize the determinant thermal parameters of the Brussels underground. From all the subsurface data collected, the BRUGEO consortium aims at mapping the geothermal potential of the BCR. This web-based mapping, accessible to design offices, installers of geothermal systems, citizens, public and private stakeholders or regional and municipalities administrations, will make it easier to foster the use of geothermal energy. The web portal will consist of an interactive decision support and a design tool based on maps built thanks to the geoscientific 3D models and geothermal parameters assessed during BRUGEO. The results are expected to be published online in March 2020.

How to cite: Petitclerc, E., Gerard, P., Devleeschouwer, X., François, B., Huysmans, M., Agniel, M., Gigot, V., Gaudaré, L., Van Lysbetten, G., and Burlet, C.: Shallow Geothermal Resources Assessment of the Brussels Region: Exploration, 3D Geological Model, Geothermal Potential Mapping and Challenges Related, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9769, https://doi.org/10.5194/egusphere-egu2020-9769, 2020.

EGU2020-21973 | Displays | ERE2.6

Expanding a Geothermal Field Downwards. The Challenge of Drilling a Deep Well in the Hengill Area, SW Iceland.

Gunnar Gunnarsson, Vignir Demusson, Ingvi Gunnarsson, Bjarni Reyr Kristjánsson, Sigrún Tómasdóttir, and Vala Hjörleifsdóttir

In 1986 a well, which was planned as a convetional production well in the Nesjavellir Field in the Hengill Area, SW Iceland, was unexpectedly drilled into a very hot formation at the depth of 2.1 km. The measured temperature in the lowest part of the well was 380°C, which was the upper range of the measuring tool used. Thus, the bottom-hole temperature was most probably higher. No one expected to hit such a hot body in this place and the well design was not appropriate to handle such high temperatures and resulting pressures. Thus, the lower parts of that well were closed off and it has since then been operated as a conventional geothermal well.

This incidence sparked the idea of drilling deeper into volcanic hydrothermal systems in Iceland in order to gain a better understanding of the roots of the geothermal systems and to be able to produce fluids with higher enthalpy. The Iceland Deep Drilling Project (IDDP) is supposed to realize that idea. The IDDP project is a consortium of domestic and international partners, both from industry and academia. The three power companies in Iceland, which operate power-production in volcanic geothermal fields (Landsvirkjun, HS-Orka, OR), committed themselves to drill one deep well each in a field of theirs.

To date two wells have been drilled in the IDDP project. The first one, IDDP-1, was drilled in the Krafla Field, N Iceland, which is operated by Landsvirkjun, and the second well, IDDP-2, was drilled in the Reykjanes Field, which is operated by HS-Orka. The original plan was to drill down to 4-5 km. However, the IDDP-1 in Krafla was drilled into magma of rhyolite composition at the depth of 2.1 km and could therefore not be drilled further. During flow tests, it was flowing superheated steam at high pressure at well head temperature of 450°C. The power capacity was estimated to be 36 MWe. However, due to hostile chemistry of the fluid and damaged casing, the well had to be abandoned and closed after the well tests. IDDP-2 was drilled down to 4,659 m. The highest temperature measured in the bottom of the well was 426°C at a pressure of 340 bar. It was also possible to obtain core samples from the bottom of the well. However, due to damaged casing it hasn't been possible to do further temperature and pressure measurements in the lower parts of IDDP-2. To date flow tests in IDDP-2 have not started.

The next well in the IDDP project is planned in the Hengill Area. The most promising target is the hot body that started it all in the Nesjavellir Field. According to experience from IDDP-1 and IDDP-2 the main techincal obstacle is the casing. Both wells have serious casing problems. The magma body unexpectedly hit by IDDP-1 illustrated that careful interdisciplinary preperations are needed when drilling into the unknown. Currently, few projects are ongoing to fill the knowledge gaps in order to minimize risk and maximize the probability of successful drilling.

How to cite: Gunnarsson, G., Demusson, V., Gunnarsson, I., Kristjánsson, B. R., Tómasdóttir, S., and Hjörleifsdóttir, V.: Expanding a Geothermal Field Downwards. The Challenge of Drilling a Deep Well in the Hengill Area, SW Iceland., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21973, https://doi.org/10.5194/egusphere-egu2020-21973, 2020.

EGU2020-11218 | Displays | ERE2.6

Diffuse H2 and He degassing survey to study of hidden potential geothermal systems in La Palma, Canary Islands

Fátima Rodríguez, Antonio Polo Sánchez, Katherine Dale, Chloe Codner, Alba Martín, Nemesio M. Pérez, Cecilia Amonte, Gladys V. Melián, Mar Alonso, and María Cordero

La Palma is one of the eastern islands of the Canary Archipelago located off the West African continental margin. Volcanic activity in the last 123 ka has taken place exclusively at the southern part of the island, where Cumbre Vieja volcano has been formed. Cumbre Vieja, one of the most active basaltic volcano in the Canaries, host seven historical eruptions being Teneguía eruption (1971) the most recent one. Cumbre Vieja volcano, characterized by a main north–south rift zone 20 km long and covering an area of 220 km2, does not show any visible degassing that show the existence of active geothermal systems. For that reason, geochemical prospecting of soil gases and volatiles in the soil matrix itself of Cumbre Vieja can provide useful information to investigate the presence of permeable areas and potential upflow areas for the degassing of geothermal systems at depth.

We report herein the results of an intensive soil gas study, focused on non-reactive and/or highly mobile gases such as helium (He) and hydrogen (H2), in Cumbre Vieja, with geothermal exploration purposes. He has unique characteristics as a geochemical tracer: it is chemically inert and radioactively stable, non-biogenic, highly mobile and relatively insoluble in water. H2 is one of the most abundant trace species in volcano-hydrothermal systems and is a key participant in many redox reactions occurring in the hydrothermal reservoir gas.

Soil gas samples were collected at 1,201 sites selected from June 2019 to September 2019, with an average distance between sites of ≈ 250 m, at ≈ 40 cm depth using a metallic probe. He content was analyzed by means of a quadrupole mass spectrometer (QMS; Pfeiffer Omnistar 422) and hydrogen concentrations by a micro-gas chromatograph (microGC; VARIAN CP490). Soil He concentration showed values up to 23.9 ppm with an average of 5.73 ppm. Soil H2 concentrations measured ranged from typical atmospheric values (≈ 0.5 ppm) up to 19.8 ppm. The mean value measured for H2 was 0.78 ppm. Although He concentration values showed high spatial variability, the highest values can be observed in the north–south rift zone of Cumbre Vieja and around the surface contact with Cumbre Nueva ridge. Spatial distribution of H2 concentration showed the highest values in the north-west area of Cumbre Vieja volcano. The results showed here are useful to identify the possible existence of permeable portions of deep-seated actively degassing geothermal reservoirs. However, a multidisciplinary approach is essential to obtain additional information about possible geothermal systems underlying at Palma island with the last goal of the selection of appropriate locations for future exploratory wells.

How to cite: Rodríguez, F., Polo Sánchez, A., Dale, K., Codner, C., Martín, A., Pérez, N. M., Amonte, C., Melián, G. V., Alonso, M., and Cordero, M.: Diffuse H2 and He degassing survey to study of hidden potential geothermal systems in La Palma, Canary Islands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11218, https://doi.org/10.5194/egusphere-egu2020-11218, 2020.

EGU2020-15267 | Displays | ERE2.6

Assessment of Petrothermal Potentials: An Exploration Scheme for Mid-German Crystalline High Basement Rocks

Sebastian Weinert, Kristian Bär, Günter Zimmermann, and Ingo Sass

Key requirement for geothermal power production are temperatures of at least 100°C, while the obtainable flow-rate mainly controls the economic viability. Many geotectonic settings only provide such reservoir temperatures in depths of 3 km or more. Hydrothermal systems reach such temperatures only in specific geotectonically active settings, e.g. the Upper Rhine Graben or the Molasse basin in Germany, and usually are already under exploration and exploitation. Besides these easily accessible hydrothermal systems, which only make up a small share of the overall geothermal potential, petrothermal systems in crystalline or metamorphic basement rocks provide a much larger and ubiquitous resource. Locating and quantifying these petrothermal potentials is still a challenging task.

A newly developed exploration scheme for petrothermal potentials is proposed and applied to the crystalline basement of the Mid-German Crystalline High in the federal state of Hesse, Germany. The exploration is composed by three tiers and subdivided in an outcrop analogue study, a conceptual geological 3D-structural model and the estimation of petrothermal potentials based on the comprehensive geothermal 3D-model composed as result of the first two tiers.

On the example of the Mid-German Crystalline High basement rocks, the assessment scheme is demonstrated. Therefore, the geological 3D-structural model which is based on geophysical, structural geological and well data is presented. Petrophysical rock properties such as porosity, grain and bulk density, compressional wave velocity but also thermal conductivity and thermal diffusivity are measured on outcrop analogue samples and fed into a custom-made weighting matrix as basis for a multi-criteria decision making system. Together with additional criteria such as reservoir geometry, rock mechanical and structural geological features, qualitative potential assessment is performed. Quantification of the petrothermal potentials will be applied by the volumetric method and assumption of recovery factors for petrothermal systems based on operating systems worldwide.

Petrothermal potentials are displayed in the geological model.

How to cite: Weinert, S., Bär, K., Zimmermann, G., and Sass, I.: Assessment of Petrothermal Potentials: An Exploration Scheme for Mid-German Crystalline High Basement Rocks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15267, https://doi.org/10.5194/egusphere-egu2020-15267, 2020.

EGU2020-8091 | Displays | ERE2.6

Slates: a potential rock type to extract geothermal energy from the underground?

Johannes Herrmann, Erik Rybacki, Wenxia Wang, Harald Milsch, Bianca Wagner, and Bernd Leiss

Commonly used host rock reservoirs for Enhanced Geothermal Systems (EGS) are composed of granite, as they display highly conductive and sustainable fracture networks after stimulation. However, considering the large amount of metamorphic rocks in Europe’s underground, these rock types may also show a large potential to extract geothermal energy from the subsurface. Within the framework of the European Union’s Horizon 2020 initiative ‘MEET (Multi-Sites EGS Demonstration)’, we are conducting fracture permeability experiments at elevated confining pressures, pc, temperatures, T, and differential stresses,

How to cite: Herrmann, J., Rybacki, E., Wang, W., Milsch, H., Wagner, B., and Leiss, B.: Slates: a potential rock type to extract geothermal energy from the underground?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8091, https://doi.org/10.5194/egusphere-egu2020-8091, 2020.

EGU2020-16953 | Displays | ERE2.6

Exploring the Deep Geothermal Energy Potential at Weisweiler, Germany: 3D-Modelling of Subsurface Mid-Palaeozoic Carbonate Reservoir Rocks

Tobias Fritschle, Martin Salamon, Silke Bißmann, Martin Arndt, and Thomas Oswald

Devonian and Carboniferous carbonate rocks are present in the subsurface of the Weisweiler lignite-fired power plant near Aachen, Germany. The utilisation of these rocks for deep geothermal energy extraction is currently being explored within the scope of the transnational EU-INTERREG-funded “Roll-out of Deep Geothermal Energy in North-West Europe (DGE-ROLLOUT)” project, which aims to provide solutions to reduce carbon-dioxide emissions using a variety of geoscientific approaches.

Marine transgressive-regressive cycles during mid-Palaeozoic times enabled the formation of extensive reef complexes on the southerly continental shelf of the Laurussian palaeocontinent. Supported by favourable climatic conditions including warm, clear and shallow waters, the Givetian to Frasnian Massenkalk facies and the Dinantian Kohlenkalk Group, each several hundred meters thick, were deposited in North-West Europe.

In the Weisweiler area, these Palaeozoic carbonate rocks were covered by voluminous paralic sedimentary rocks and deformed to large-scale, generally northeast-southwest-trending, syncline-anticline structures during the Variscan Orogeny. Alpine (post-)orogenic processes further induced faulting, resulting in fault-block tectonics in the Lower Rhine Embayment area of tectonic subsidence. Significant multiphase karstification of the Palaeozoic carbonate rocks, which can be observed in nearby exposed counterparts, supports their enhanced geothermal exploitation potential.

3D-modelling of the depths and dimensions of the Weisweiler subsurface carbonate reservoirs is carried out using the commercial software Move [v2019.1.0; Petroleum Experts Ltd], and is constrained by lithostratigraphic data obtained from drilling operations, geological mapping, and interpretation of seismic profiles. The 3D-model exhibits a complex geotectonic environment, including the development of both parasitic folds and thrust faults prior to the generation of Tertiary fault-block tectonics. The depths of the tops of the reservoirs are estimated to c. 1,200 m for the Carboniferous and to c. 2,000 m for the Devonian carbonate rocks, taking into account typical thicknesses of the overlying and underlying strata. Considering possible tectonic repetition below the thrust faults, the reservoir rocks may also occur significantly deeper in the subsurface. The 3D-model is currently being transformed into a HeatFlow3D [DMT GmbH & Co. KG] / Petrel [v2017; Schlumberger N.V.] model in order to approximate the fluid circulation and pathways within the carbonate reservoirs.

Based on the current model, a target area for 2D-seismic surveys and a c. 1,000 to 1,500 m deep exploration borehole have been selected. These investigations will commence in the summer of 2020, and will then enable geochemical and petrophysical investigations of the Palaeozoic rocks. The possibility of deep geothermal energy extraction from the Weisweiler subsurface and subsequent evaluation of the transition of the conventional lignite-fired power plant towards its utilisation of renewable “green” energy is carried out in close collaboration with DMT GmbH & Co. KG, Fraunhofer Institute for Energy Infrastructures and Geothermal Energy and RWE Power AG, all partners within the DGE-ROLLOUT project. The successful realisation of this project may serve as a pilot for similar projects considering the forthcoming fossil fuel phase-out.

How to cite: Fritschle, T., Salamon, M., Bißmann, S., Arndt, M., and Oswald, T.: Exploring the Deep Geothermal Energy Potential at Weisweiler, Germany: 3D-Modelling of Subsurface Mid-Palaeozoic Carbonate Reservoir Rocks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16953, https://doi.org/10.5194/egusphere-egu2020-16953, 2020.

EGU2020-8291 | Displays | ERE2.6

A mine as a source of geothermal energy - case study from Pyhäsalmi, Finland

Kaiu Piipponen, Jaakko Hietava, Nina Leppäharju, Annu Martinkauppi, Kimmo Korhonen, and Lasse Ahonen

Water pumped from flooded coal mines has been considered as a promising option to extract geothermal energy in many countries situating in sedimentary rock environment, where the ground temperatures are clearly higher than those of the crystalline rocks of the Fennoscandian Shield. Extraction of metals from the 1440 m deep Cu-Zn-S mine in Pyhäsalmi, Finland, will end in the near future. This provides us an optimal environment for studying how much heat energy can be utilized at depths of 500-2500 meters and which method would be the optimal for it. In the Pyhäsalmi Energy Mine project funded by European Regional Development Fund (ERDF) we investigated the geothermal energy potential of the crystalline rock, performance of different borehole heat exchangers and optimized the deep borehole field.

Geothermal potential of the Pyhäsalmi site has the typical constraints of the Finnish crystalline bedrock. Field measurements include temperature measurements of ten different boreholes using Distributed Temperature Sensing (DTS) method. Near-surface annual average temperature is about 4 °C and geothermal gradient is 12-14 K/km. The ore deposit is hosted by metavolcanic rocks (ca. 1.9 Ga). Laboratory measurements show that felsic metavolcanics prevailing in immediate contact with ore have thermal conductivity of 3 – 3.5 W/(m·K), whereas the mafic metavolcanics mainly on the western side of the ore body have thermal conductivity of 2.5 – 3 W/(m·K). Relatively high thermal conductivity of the low-porosity crystalline rock promotes heat extraction from the bedrock temperatures 20 – 25 °C prevailing in the bottom of the mine.

The generated and optimized design concept in this project is based on an underground borehole field and a novel insulated coaxial collector type transferring heat from the bedrock to the fluid circulation system. A technical challenge to be resolved is the heat transfer from the depths of the mine to the ground surface. The borehole field placed at the bottom of the mine can be dimensioned to produce nearly 20 °C water with several megawatts power, allowing annual heat production of up to 10 GWh at the temperature range of 70 – 90 °C by means of heat pumps. This allows the use of geothermal heat in district heating network, something not yet done anywhere in Finland. Moreover, the borehole field can be utilized both for heat extraction and charging, making it possible to use the borehole field as a heat storage in a distributed heating network.

 

How to cite: Piipponen, K., Hietava, J., Leppäharju, N., Martinkauppi, A., Korhonen, K., and Ahonen, L.: A mine as a source of geothermal energy - case study from Pyhäsalmi, Finland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8291, https://doi.org/10.5194/egusphere-egu2020-8291, 2020.

EGU2020-13556 | Displays | ERE2.6

3D basin-scale groundwater flow modeling as a tool for geothermal prospection of the Geneva Basin, Switzerland-France

Marion Alcanie, Marine Collignon, Olav Møyner, and Matteo Lupi

Switzerland supports the energetic transition by promoting the development of geothermal energy among other renewable energies. In particular, the Canton of Geneva is actively prospecting the Geneva Basin, generating a large dataset of geophysical and geological information. This large dataset of the Geneva Basin is used here to constrain geologically complex numerical models of fluid flow. Previous and ongoing projects demonstrated the geothermal potential of the Geneva Basin but a consistent basin-scale fluid flow model of the area has yet to be defined.

We use MRST (Matlab Reservoir Simulation Toolbox) for which we recently developed a geothermal module. The module is available with the last MRST release (2019b) and it is used to build up a 3D basin-scale dynamic model of the Geneva Basin. The goal of our numerical study is to investigate the large-scale control of tectonic structures and lithological hetherogeneities on fluid flow in the basin.

The static model is derived from active seismic and gravity inversion data. Petrophysical data and geo-location of faults are obtained from the existing literature. The resulting heterogeneous model takes into account the main geological facies, observed in the basin. We define a reference simulation with standard initial conditions (geothermal gradient and hydrostatic pressure topographically corrected) and a basal incoming heat flux. We consider a single-phase pure water compressible laminar flow in porous media. The geothermal module solves the mass and energy conservation equations using a fully implicit finite-volume discretisation with two-point flux approximation and single-point upstream mobility weighting.

We design a parametric study along three main axis: tectonic structures (i.e. faults), petrophysical and thermal properties and perform twenty three simulations running for 500 000 years to reach an equilibrium flow (steady-state). Our results show that fluid flow is driven by the hydraulic head of the topographic highs bounding the basin. Hotter fluids are found in the centre of the basin where we propose to focus geothermal exploitation in the future. Our results represent, to our knowledge, the first example of 3D basin-scale fluid flow modelling used as a preliminary prospection method for the assessment of geothermal resources.

How to cite: Alcanie, M., Collignon, M., Møyner, O., and Lupi, M.: 3D basin-scale groundwater flow modeling as a tool for geothermal prospection of the Geneva Basin, Switzerland-France, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13556, https://doi.org/10.5194/egusphere-egu2020-13556, 2020.

EGU2020-21633 | Displays | ERE2.6

Lessons learned from injection into sedimentary geothermal aquifers

Maren Brehme, Abel Marko, Santiago Aldaz, Guido Blöcher, and Ernst Huenges

Reasons for injectivity decline were investigated at different geothermal sites in Europe. Due to low injectivities, production rates have to be reduced and the site faces negative commercial implications. In addition to historical operation data, fluid and rock samples were investigated in the laboratory. Analysis and experiments focus on physical, chemical and biological processes and their interaction. Results show different processes being responsible for injection-triggered occlusion of flow pathways, e.g. fines migration, precipitation, micro-biological activity, aquifer properties, corrosion or O2 inflow.

Lessons learned will be shown, from preparation of large-scale projects, from monitoring programmes towards sustainable operation.

Activities are taking place in the frame of the DESTRESS project. The DESTRESS project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 691728.

How to cite: Brehme, M., Marko, A., Aldaz, S., Blöcher, G., and Huenges, E.: Lessons learned from injection into sedimentary geothermal aquifers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21633, https://doi.org/10.5194/egusphere-egu2020-21633, 2020.

EGU2020-21970 | Displays | ERE2.6

Geothermal resources characterization of two areas in southern Tuscany

Eugenio Trumpy, Gianluca Gola, Alessandro Santilano, Adele Manzella, Matteo Brambilla, Roberto Calabrò, Marco Giussani, Roberto Monti Colombani, Salvatore Palumbo, Vincenzo Savoca, and Emery Vajda

Based on a joint analysis of geothermal indicators (e.g. temperature map at different depth, surface heat flux) and practical features (e.g. restricted areas, existing research lease), two promising areas in southern Tuscany were identified to perform a more detailed geothermal resource characterization. An area is located on the north-east of the Larderello-Travale geothermal field, and the other one is located on the west of the Mt. Amiata geothermal field.

A quantitative geothermal resources assessment was performed in the aforementioned areas of Tuscany by solving numerical thermo-fluid dynamic models and by computing the geothermal potential using the ‘ThermoGIS’ software, as further developed for the Italian case (Trumpy et al., 2016).

First of all, geological and geophysical data required for geological and thermo-fluid dynamic modelling were collected and organised. The geological data were used to build a 3D geological model of the two areas of interest suitable for numerical simulations. Static temperature data gathered from the Italian National Geothermal Database together with site-specific heat flow measurements were used to calibrate the simulated steady state temperature distribution.

The geothermal potential computed by integrating geological, thermal and petro-physical information implementing the volume method used in ThermoGIS provided estimates of the heat in place and the geothermal technical potential maps. The resulting technical potential in the area close to Larderello –Travale is 330 MWe and in the Mt. Amiata sector is 50MWe.

References

Trumpy E., Botteghi S., Caiozzi F., Donato A., Gola G., Montanari D., Pluymaekers M., Santilano A., Van Wees, J.D., Manzella A. Geothermal potential assessment for a low carbon strategy: a new systematic approach applied in southern Italy. Energy 103, 167-181, 2016.

How to cite: Trumpy, E., Gola, G., Santilano, A., Manzella, A., Brambilla, M., Calabrò, R., Giussani, M., Monti Colombani, R., Palumbo, S., Savoca, V., and Vajda, E.: Geothermal resources characterization of two areas in southern Tuscany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21970, https://doi.org/10.5194/egusphere-egu2020-21970, 2020.

EGU2020-1164 | Displays | ERE2.6

Soil gas CO2 concentration, isotopic ratio and efflux measurements for geothermal exploration at Cumbre Vieja volcano, La Palma, Canary Islands

Alba Martín Lorenzo, Banner Cole, Elizabeth Bullock, Sahlla Abassi, Lía Pitti-Pimienta, Ana Meire, Cecilia Amonte, Gladys V. Melián, Pedro A. Hernández, and Nemesio M. Pérez

The exploration of geothermal resources on the island of La Palma, Canary Islands, was first conducted by the Spanish Geological Survey (IGME) from 1982 to 1984. These studies were focused exclusively on the southern part, where the last historical eruption, Teneguía, took place in 1971. This area still shows some geothermal features such us relatively high ground water temperatures (about 40ºC) and soil CO2 efflux values. Recent studies carried out at Cumbre Vieja volcano, the southern part of the island, on diffuse degassing, 3D gravimetry and Audio-MT probes point to promising results, although more studies are needed. We continue applying a multidisciplinary approach to obtain additional information about the geothermal system underlying at Palma island using novel techniques as well as tools which are appropriate to evaluate this system. For this reason, during summer 2019 a soil diffuse degassing research started at Cumbre Vieja volcano (220 km2) for geothermal exploration purposes. In this first phase of the diffuse degassing study about 1,200 sampling sites, with an average distance between sites of approximately 250 m were selected after taking into consideration the volcano-structural features and accessibility. In each sampling site in-situ soil CO2 efflux measurements were performed, and soil gas samples were collected at 40 cm depth for chemical and isotopic analysis. Spatial distribution of CO2 efflux, statistical-graphical analysis of CO2 efflux, and δ13C-CO2 isotopic data to calculate and map the volcano-hydrothermal contribution of CO2 were combined and used for geothermal exploration. The statistical-graphic analysis of the diffuse CO2 efflux values confirms the existence of different geochemical populations showing two log-normal geochemical populations, a fact that suggests the addition of deep-seated CO2. Relatively low CO2 efflux values were measured ranging from non-detected up to 72.8 g m-2 d-1, with an average value of 4.6 g m-2 d-1. The highest CO2 efflux values were measured at the north end of Cumbre Vieja, around the surface contact with Cumbre Nueva ridge. The CO2 isotopic composition, expressed as δ13C- CO2 showed the contribution of three different end-members: biogenic, atmospheric and deep-seated CO2. The results indicate that most of the sampling sites exhibited CO2 composed by different mixtures between atmospheric and biogenic CO2 with slight inputs of deep-seated CO2, with a mean value of -15.3‰, being the maximum and the minimum -2.8‰ and -25.4‰ respectively. The results showed here can help to identify the existence of zones where deep-seated actively degassing from geothermal reservoirs occurs, particularly where the interpretation and application of geophysical data might be difficult.

How to cite: Martín Lorenzo, A., Cole, B., Bullock, E., Abassi, S., Pitti-Pimienta, L., Meire, A., Amonte, C., Melián, G. V., Hernández, P. A., and Pérez, N. M.: Soil gas CO2 concentration, isotopic ratio and efflux measurements for geothermal exploration at Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1164, https://doi.org/10.5194/egusphere-egu2020-1164, 2020.

EGU2020-1225 | Displays | ERE2.6

The role of fractures in flow partitioning during minewater geothermal energy extraction

Mike Chandler, Julian Mecklneburgh, and Ernest Rutter

The UKGEOS Glasgow research field site comprises a network of 12 boreholes into flooded coal mines, and is designed to observe how warm water moves around the abandoned mine workings over time (Monaghan et al., 2018). Minewater geothermal projects involve the redevelopment of abandoned mining areas into large volume, low temperature resources and use heat pumps to drive heating for homes, industry or agriculture. This technique has proven potential as a renewable, decarbonised heat source providing reliable heating, cooling and heat storage with stable pricing to former mining areas.

Flow through minewater systems is partitioned between flow through the mine voids, through fractured media, and through porous media. This heterogeneity in flow is crucial to the development of models to predict the efficacy of minewater geothermal systems, as water flowing through the fractured material should absorb more heat than that flowing directly through the mine voids. This heat exchange then goes on to control the rate at which heat can be sustainably extracted from the minewater system.

The majority of fluid flow has generally been assumed to be through the mine voids. However, the proportion of fluid flow through the porous wallrocks is very sensitive to the fracture populations that they contain, due to the shallow nature of these mine workings leaving them under low stress.  Geothermal tests at the Gaspé mines in Québec demonstrate this clearly, with high wallrock conductivities (10-6-10-4 m.s-1) attributed to mine-blasting (Raymond & Therrien, 2008). Coal mining in the Glasgow area was predominantly carried out using the Pillar & Stoop or Longwall methods, which lead to very different damage states in the wallrocks, and so the effect of these fracture populations is expected to have a large effect on flow partitioning.

Here, relationships between in-situ stress, fracture population and permeability were determined from well-core samples of the Glasgow Main Coal and underlying mudstone and sandstone strata, in order to characterise how flow may be partitioned within different regions of these mine-workings.

Stress-dependent permeability and storativity were measured using the osciallting pore-pressure method, and elastic tensors were determined using an array of ultrasonic transducers. Axial fractures were then generated within these samples under low triaxial stress states, and the change in permeability with induced fractures then measured at a single stress state, with the newly developed fracture population characterised through the changes in the elastic tensor.

Monaghan, A. A., Starcher, V., Dochartaigh, B. É. Ó., Shorter, K., & Burkin, J. (2018). UK Geoenergy Observatories : Glasgow Geothermal Energy Research Field Site - Science infrastructure. http://nora.nerc.ac.uk/id/eprint/521444/%0A

Raymond, J., & Therrien, R. (2008). Low-temperature geothermal potential of the flooded Gaspé Mines, Québec, Canada. Geothermics. https://doi.org/10.1016/j.geothermics.2007.10.001

How to cite: Chandler, M., Mecklneburgh, J., and Rutter, E.: The role of fractures in flow partitioning during minewater geothermal energy extraction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1225, https://doi.org/10.5194/egusphere-egu2020-1225, 2020.

EGU2020-3911 | Displays | ERE2.6

Poroelasticity and self-stimulation around geothermal producers in quadruplet versus triplet configurations

Derrick Adu Ntow, Julia Ghergut, Martin Sauter, Bianca Wagner, Bettina Wiegand, and Mohammed Yamah

At the real-world site underlying the scoping simulation example, adding a fourth well (second producer) is being endeavored in order to maximize the benefit from an unexpectedly high injectivity at the already existing two injectors, whereas the modest productivity of the existing producer is acting as the turnover-limiting factor in the currently operating triplet. Up-sizing to a quadruplet configuration (two producers instead of one) might thus also, by virtue of competing pressure diffusion and poroelastic effects, improve the productivity of the first producer, so to say as an ‘added bonus’ for up-sizing. In the currently operating triplet regime, injectivity also appears to increase with operation time i. e. with the cumulative volume of fluid turnover, this being attributed to (thermo-)hydrogeochemical rather than hydraulic-poroelastic effects. Scoping poroelastic simulations are complemented by a comparison of fluid residence time distributions and thermal lifetime expectations between the two (quadruplet versus triplet) configurations.

How to cite: Adu Ntow, D., Ghergut, J., Sauter, M., Wagner, B., Wiegand, B., and Yamah, M.: Poroelasticity and self-stimulation around geothermal producers in quadruplet versus triplet configurations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3911, https://doi.org/10.5194/egusphere-egu2020-3911, 2020.

EGU2020-4125 | Displays | ERE2.6

Geochemistry of geothermal fluids in Moil Valley geothermal field, NW Iran

Rahim Masoumi, Farahnaz Bakhshandeh GharehTapeh, and Bahman Bakhshandeh GharehTapeh

The Moil valley geothermal field is located in the northwest of Sabalan volcano in the northwest of Iran. The geothermal activities attributed to the Sabalan volcano was intensified during Plio-Quaternary time and the manifestations of these activities are observable around the volcano especially in the northwestern corner. The hot springs, surficial manifestations, and extracted fluids from drilled wells represent the whole composition of underground reservoir fluids. The thermal measurement of fluids show wide ranges of temperature of fluids where the hottest spring show 89˚C and the fluids obtained from well samplings show maximum temperature of 202˚C.  

The reservoir temperature estimations based on different geothermometers show 250˚C for the reservoir. The interpretation of carried out chemical analyses represent Na-K-Cl dominant composition for the studies samples taken from hot springs and drilled wells. All of sampling stations show pH ranges of 4.2-7.6 which reveal acidic to neutral pH range. The variation of TDS for the studied samples ranges between 209 to 320 mg/L. The evaluation of correlation coefficients between main parameters gives notable results. The positive and good correlation coefficient between temperature and Cl is obvious in most of samples and consequently the Cl content of samples increases in high temperature samples.        

Boron as a key constituent in geothermal fluids show variable concentrations in Moil Valley geothermal fluids and shows 0.28-35 mg/L Boron content in the studied samples. The correlation between Boron and pH for the studied samples is positive. This correlation displays the highest concentrations in pH=7. The main Boron species in this pH value is B(OH)3 which is more stable comparing to the other Boron phases.  

The stable isotope analyses of the studied samples show -12 to -9.1‰ for δ18O and -71.3 to -77.6‰ for δD. The interpretation of obtained δ18O and δD values represents the main role of meteoric waters in reservoir fluids of Moil Valley geothermal field. Magmatic waters show negligible share of the reservoir fluids.      

The Tritium analyses for the studied samples show 0.1 to 41.7 TU amounts. The evaluation of obtained Tritium contents reveals the circulation of young waters inside the reservoir and considering to the δD/δ18O ratios, it is most likely that the recharge zones of the reservoir are situated in close distance and there are evidences of mixing with meteoric waters.

How to cite: Masoumi, R., Bakhshandeh GharehTapeh, F., and Bakhshandeh GharehTapeh, B.: Geochemistry of geothermal fluids in Moil Valley geothermal field, NW Iran, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4125, https://doi.org/10.5194/egusphere-egu2020-4125, 2020.

EGU2020-4685 | Displays | ERE2.6

Influence of fluid flow and heat transport on predictions of geothermal potentials in sedimentary layers of Hesse (Germany)

Nora Koltzer, Maximilian Frick, Magdalena Scheck-Wenderoth, Björn Lewerenz, Kristian Bär, and Judith Bott

For the sustainable utilization of deep geothermal resources it is essential to predict the exploitable potential thermal energy from the subsurface. One main parameter influencing the geothermal potential is the reservoir temperature that may vary locally or regionally in response to fluid flow and heat transport processes.

This study aims at combining highly complex 3D thermo-hydraulic numerical simulations of heat transport and fluid flow with predictions of the geothermal potential for the application case of a hydrothermal doublet. Quantifying the influences of conductive, advective and convective heat transport mechanisms on the thermal field and moreover on the predicted heating power requires fundamental numerical investigations. We use the Federal State of Hesse in Germany as study area where heat transport processes have been quantified in recently published studies. There, the heterogeneous geology consists of outcropping Variscan Crust and up to 3.8 km and 1.8 km thick sedimentary deposits of the Upper Rhine Graben and the Hessian Depression, respectively. This geological complexity is expressed by areas of different hydraulic and thermal configurations: in the flat, but tectonically active Upper Rhine Graben high heat flow from below the graben sediments is in contrast to the variable topography of the Hessian Depression with low heat input from the Rhenohercynian Basement.

The heating power in the three reservoir units (I) Cenozoic, (II) Buntsandstein and (III) Rotliegend is only predicted to be high in the Upper Rhine Graben. There the reservoir temperature is high enough and varies between 50 °C in the convective thermal model of the Cenozoic reservoir and 170 °C in the conductive thermal model of the Buntsandstein reservoir. Predicted low temperatures in the Hessian Depression lead to negligible low heating power, but as production mass flux is above ~6 kg s-1 investigations should continue to assess the geothermal potential for other applications like seasonal energy storage or low enthalpy geothermal utilization.

How to cite: Koltzer, N., Frick, M., Scheck-Wenderoth, M., Lewerenz, B., Bär, K., and Bott, J.: Influence of fluid flow and heat transport on predictions of geothermal potentials in sedimentary layers of Hesse (Germany), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4685, https://doi.org/10.5194/egusphere-egu2020-4685, 2020.

EGU2020-4979 | Displays | ERE2.6

Two methods for temperature measurement in super-hot geothermal systems based on synthetic fluid inclusions

Giovanni Ruggieri, Andrea Orlando, Daniele Borrini, Stefano Caporali, and Tobias B. Weisenberger

Super-hot geothermal systems are promising targets for near future geothermal exploration either for direct fluid exploitation or as potential reservoirs of Enhanced Geothermal Systems. Although reservoir conditions assessment is crucial for the evaluation of the geothermal resources, temperature measurement is still a major challenge in super-hot systems since their extreme conditions (i.e. very-high temperature, possible presence of aggressive fluids) preclude the use of conventional logging methods. During two EU projects (i.e. IMAGE (FP7) and the DESCRAMBLE (H2020)) two methods based on fluid inclusions synthesis were developed for in-situ measurements of very high-temperature (i.e. ≥400°C). Synthetic fluid inclusions are produced by trapping fluid within pre-fractured minerals, free of natural fluid inclusions, placed in a gold capsule together with an aqueous solution. Laboratory tests showed that fluid inclusions in quartz form in a relatively short time (down to 48 hours) if an alkaline-saline solution (0.4 M of NaOH + 10 to 20 wt.% NaCl) is used. In the first method synthetic fluid inclusions in quartz chips are produced within gold capsules placed inside a micro-reactor containing a volume of de-ionised water in such amount that the density of water in the micro-reactor has the critical value. Under these conditions, the trapping temperature of synthetic inclusions can be computed by the intersections between inclusion isochores, determined through microthermometry, and the critical isochore of water. Thus, if the micro-reactor is kept for at least 48 hours at the depth of measurement in a geothermal well, the trapping temperature of fluid inclusions formed in capsules would correspond to the well temperature at that depth. The second method consists in the production of fluid inclusions in gold capsules in direct contact with the environment of the geothermal well. Under the conditions of the super-hot systems characterized by relatively low pressure (such as the deepest part of the Larderello-Travale geothermal system in Italy), pressure-temperature conditions would cause fluid immiscibility in the gold capsule (i.e. the saline-alkaline fluid splits in a high-salinity liquid and a low-salinity vapor). In this case, the trapping temperature of both high-salinity and low-salinity inclusions is equal to their homogenization temperature. Laboratory tests demonstrated that the trapping temperatures of fluid inclusions produced by both methods can provide a good estimate of the experimental temperatures. Two field tests following the first method were performed in geothermal wells of Krafla (Iceland) and Larderello-Travale (Italy) characterized by measured temperature at the test depth of 336°C and 249°C, respectively. These tests showed that synthetic fluid inclusions trapping temperatures closely approach the temperature measured using conventional methods. Finally, a field test was also attempted in the Venelle 2 (Larderello-Travale) geothermal well characterized by super-hot conditions. Trapping temperatures of fluid inclusions formed at 2900 below ground level (b.g.l.) by both methods resulted compatible with independent measurement by an electronic device which gave 444°C at 2810 m b.g.l..

The research leading to these results has received funding from the EC Seventh Framework Programme under grant agreement No. 608553 (Project IMAGE) and from the Horizon 2020 Programme under grant agreement 640573 (Project DESCRAMBLE).

How to cite: Ruggieri, G., Orlando, A., Borrini, D., Caporali, S., and Weisenberger, T. B.: Two methods for temperature measurement in super-hot geothermal systems based on synthetic fluid inclusions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4979, https://doi.org/10.5194/egusphere-egu2020-4979, 2020.

EGU2020-5612 | Displays | ERE2.6

Fluid-driven anthropogenic micro-seismic activity while drilling towards supercritical conditions in the Larderello-Travale geothermal field

Domenico Montanari, Riccardo Minetto, Thomas Plànes, Marco Bonini, Chiara Del Ventisette, Veronica Antunes, and Matteo Lupi

This study investigates the seismic activity occurring at the Larderello-Travale geothermal field (LTGF), central Italy, from June 2017 to January 2018. We deployed a network composed of 9 broadband stations around the Venelle 2 well drilling for supercritical fluids. During the experiment, we recognise a group of events that usually occur in swarms and that show a periodic pattern, a narrow frequency band, and almost identical waveforms. Their source is estimated to be located near the well, and their occurrence ceases after about 3 weeks from the conclusion of the drilling. We propose a causal link with the drilling operations where pressure fronts inside the well may promote phase changes and fluid flow across the drilled formations.

Our study sheds light on the anthropogenic seismic activity at the LTGF. More generally, we show that microseismic activity occurring during drilling in high-pressure and high-temperature conditions can remain at low magnitudes and that geothermal wells targeting geothermal fluids in such systems may be handled safely despite the critical conditions encountered at depth. The drilling of the Venelle 2 well is an encouraging example for the development of geothermal energy in critical conditions.

How to cite: Montanari, D., Minetto, R., Plànes, T., Bonini, M., Del Ventisette, C., Antunes, V., and Lupi, M.: Fluid-driven anthropogenic micro-seismic activity while drilling towards supercritical conditions in the Larderello-Travale geothermal field , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5612, https://doi.org/10.5194/egusphere-egu2020-5612, 2020.

EGU2020-6051 | Displays | ERE2.6

Unmanned arial system imaging and refined geologic modelling of the Waiwera geothermal Reservoir

Melissa Präg, Ivy Becker, Thomas R. Walter, and Michael Kühn

The utilization of geothermal reservoirs as alternative energy source is becoming increasingly important worldwide. Details of rock properties, structures, heat transfer and resulting interactions are the basis for the implementation of a sustainable reservoir management, but are often not well enough understood. The investigated warm water reservoir in Waiwera, New Zealand, has been known for many centuries. Triggered by overproduction in the third quarter of the 20th century, the reservoir pressure dropped significantly and in the 1970s the natural seeps on the beach dried up [1]. However, the shutdown of the main user's pumps (Waiwera Thermal Pools) in 2018 led to renewed temporary and location-specific artesian activity. The question now is whether the seeps on the beach will also reappear?

Hydrogeological models are the basis for a sustainable management of groundwater resources. The key point for the Waiwera reservoir is the amount of geothermal water which is permanently available. However, models are also used to describe the current hydraulic and thermal situation of the study area [2].

An expedition was carried out in 2019 to investigate the artesian activity of the reservoir, which has been observed again since 2018, and to build a new geological model. For the first time, thermal cameras carried by unmanned aerial systems (UAS) show the emergence of warm water at the beach and photogrammetric analyses carried out allow structural and lithological mapping on exposed cliffs where localized thermal anomalies were identified for the first time. The Waitemata formation found there is considered as analogue of the reservoir rock and thus serves for an improved understanding of the subsurface reservoir properties. The analyses show individual water and heat conducting lithologies and thus provide details about geological units that also constitute the geothermal reservoir at depth.

Based on the field exploration and the associated structural interpretations, a geological and thermal 3D model is now available for the first time, which will be employed to improve calibration of the hydraulic conditions of the warm water reservoir. Further, the model will be applied in the context of a sustainable reservoir management to clarify the question about the natural seeps on the beach. The reappearance of artesian activity in the Waiwera area due to significant adaptation of production rates is unique but the improved understanding of the interaction between rock properties, existing structures and heat transfer will also enable other reservoirs to be better understood.

[1] Kühn M., Stöfen H. (2005) A reactive flow model of the geothermal reservoir Waiwera, New Zealand. Hydrogeology Journal 13, 606-626

[2] Kühn M., Altmannsberger C., Hens C. (2016) Waiwera’s warm water reservoir – What is the significance of models? Grundwasser 21, 107-117

How to cite: Präg, M., Becker, I., Walter, T. R., and Kühn, M.: Unmanned arial system imaging and refined geologic modelling of the Waiwera geothermal Reservoir, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6051, https://doi.org/10.5194/egusphere-egu2020-6051, 2020.

EGU2020-6769 | Displays | ERE2.6

Integration of geophysical methods and fractures study for the Vallès geothermal system characterization (NE Spain)

Gemma Mitjanas, Juanjo Ledo, Pilar Queralt, Gemma Alías, Perla Piña, Alex Marcuello, and Anna Martí

The Vallès geothermal system is located in the Catalan Coastal Ranges (CCR) (NE Spain). The CCR are formed by horst and graben structures limited by NE-SW and ENE-WSW striking normal faults, developed during the opening of the Valencia Trough (northwestern Mediterranean) (Gaspar-Escribano et al., 2004). In the Vallès Basin area, the thermal anomaly is located in the northeastern horst-graben limit, where a highly fractured Hercynian granodiorite is in contact with Miocene rocks by a major normal fault. This main structure seems to control the heat and the hot-water flow, nevertheless, the geological structure of this area, as well as the role of the Vallès normal fault, is poorly understood.

Magnetotellurics and gravity methods together with a detailed geological map have been applied in this area to understand the main structure. Although the geophysical part makes up most of the study, we are also elaborating a detailed geological map of the area, making a fractures study at different scales. We are working with DEM alignments analysis, and fractures study from outcrops and thin sections.

Our preliminary results in gravity show a strong gravity gradient in the NE-SW Vallès half-graben system and the recent MT profiles image the main fault of that system (Vallès normal fault). These results show a basin geometry with the major thickness of the basin towards the depocenter, disagreeing with the roll-over geometry assumed in previous works.

Interpretations of the fractures study, together with geophysical data and models, have allowed a preliminary characterization of damage zones associated with the fault system, which are directly related to the fluid flow and the hot springs. The nature of this damage zones could be related to relay ramps, commonly regarded as efficient conduits for fluid flow (Fossen and Rotevatn, 2016).

How to cite: Mitjanas, G., Ledo, J., Queralt, P., Alías, G., Piña, P., Marcuello, A., and Martí, A.: Integration of geophysical methods and fractures study for the Vallès geothermal system characterization (NE Spain), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6769, https://doi.org/10.5194/egusphere-egu2020-6769, 2020.

The Federal Institute for Geosciences and Natural Resources (BGR) has drilled the approx. 3,900m deep geothermal well Groß Buchholz Gt1 as part of the GeneSys geothermal project. The Bunter sandstone (Lower Triassic) was initially recovered as the target formation for the borehole. Due to the difficult geological conditions found, it was decided to abandon the Bunter sandstones. It is now intended to heat the properties of the GEOZENTRUM Hannover (GZH) using a geothermal doublet. In addition to the direct benefit for the GZH from the utilization of this regenerative energy source and the associated relief for the environment, the demonstration of the use of multiple, low thickness sandstone layers is of particular importance in this project. It should be proven that the sandstones of the Wealden formation (Lower Cretaceous / Berriasian) at a depth of approximately 1200m are suitable for geothermal usage. Moreover, a reference site for locations with similar geological conditions will be created.

As a requirement for further technical work in the borehole, a bottom cementation will be carried out at the final depth of the wellbore. This seals the perforation at a depth of approx. 3,700m and the access to the Bunter sandstones. A sidetrack is then drilled out of the existing hole into the Wealden sandstones. For this, a window is milled at a depth of approx. 750m and the sidetrack is drilled down to a depth of approx. 1300m. The determination of the landing point of the sidetrack is the subject of current investigations, as the Wealden sandstones are spatially heterogeneous. The reinterpretation of existing seismic profiles is of great importance for this. After successful completion of the sidetrack and evaluating the production tests and after a successful production test a second well is drilled from the same drilling site to a target depth of approx. 1300 m. The calculated distance of the two holes at the target depth is approx. 500 m.

In the previous project, the sandstone layers of the Lower Cretaceous were examined for their suitability for geothermal use. A maximum expected transmissibility can be estimated from the sum of six suitable sandstone units (total 46m), as well as the average permeability of these units of approx. 75mD. This results in a maximum transmissibility to be expected of approx. 3.5Dm. The measured temperature at a depth of 1200m is exceptionally high with 69°C.

In order to further increase the productivity of the drilling, it is planned to open up or stimulate the target horizons with different drilling techniques: for example, radial jet drilling and / or acid stimulation.

How to cite: Stechern, A., Torsten, T., and Prevedel, B.: GeneSys Doublet: setup and test of a geothermal well doublet in Lower Cretaceous sandstones of northern Germany – an outlook., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9266, https://doi.org/10.5194/egusphere-egu2020-9266, 2020.

EGU2020-9865 | Displays | ERE2.6

Local earthquake tomography at the Los Humeros geothermal field, Mexico

Tania Toledo, Philippe Jousset, Emmanuel Gaucher, Hansruedi Maurer, Charlotte Krawzcyzk, Marco Calò, and Angel Figueroa

The GEMex* project is a recently finalized European-Mexican collaboration that aimed to improve the understanding of two geothermal fields: Acoculco and Los Humeros Volcanic Complex . These sites are located in the Trans-Mexican Volcanic Belt, a region that hosts numerous active volcanoes and is favorable for geothermal exploitation. Currently, the  Los Humeros Volcanic Complex is one of Mexico’s main geothermal systems with an installed capacity of ~95MW. Many studies have been performed at this site since the 70s highlighting several features and characteristics of the shallow subsurface. However a thorough knowledge of structures and behavior of the system at greater depths is still quite sparse. Hence one main objective of the GEMex project was to conduct several geological, geochemical, and geophysical experiments to investigate deeper structures for future development of local and regional geothermal resources.

In this framework, for the period of one year (September 2017 to September 2018), a seismic array consisting of 45 seismic stations was set to record continuously at the Los Humeros Volcanic Complex. In this study we analyzed the continuous seismic records to detect the micro-seismicity mainly related to exploitation activities. After applying a recursive STA/LTA detection algorithm, we assembled and manually picked P- and S- phases of a catalog of about 500 local events. The detected events were mostly clustered around injection wells, with fewer events located close to known structures. We use the retrieved catalog to derive a new minimum 1D velocity model for the Los Humeros site. We then performed a joint inversion to obtain the 3D Vp and Vp/Vs structures of the geothermal field. A post-processing averaging of several inversions was also computed to increase resolution of the investigated region. In this study we will show the derived Vp and Vp/Vs models for the  Los Humeros Volcanic Complex to emphasize various underground structures and potentially identify possible variations due to changes in temperature, fluid content, and rock porosity.

 

*This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 727550 and the Mexican Energy Sustainability Fund CONACYT-SENER, project 2015-04-68074. We thank the Comisión Federal de Electricidad (CFE) for kindly granting the access to the geothermal field for installation and maintenance of seismic stations.

How to cite: Toledo, T., Jousset, P., Gaucher, E., Maurer, H., Krawzcyzk, C., Calò, M., and Figueroa, A.: Local earthquake tomography at the Los Humeros geothermal field, Mexico, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9865, https://doi.org/10.5194/egusphere-egu2020-9865, 2020.

EGU2020-11305 | Displays | ERE2.6

Geothermal prospecting at Cumbre Vieja volcano (La Palma, Canary Islands) by ground radon and thoron measurements

Lía Pitti-Pimienta, Anson Weidner, Rishi Shah, Rae L. McClintock, Alba Martín-Lorenzo, Claudia Rodríguez-Pérez, Eleazar Padrón, María Asensio-Ramos, Pedro A. Hernández, Fátima Rodríguez, and Nemesio M. Pérez

During geothermal exploration, the geochemical methods play a major role in both exploration and exploitation phases. Discovery of new geothermal systems requires exploration of areas where the resources are either hidden or lie at great depths. A good example of young volcanic territory with high geothermal potential where geothermal resources are either hidden or lie at great depths is La Palma island (Canary Islands). La Palma is one of the youngest and westernmost island of the Canarian archipelago, located at the West African continental margin. Cumbre Vieja volcano (220 km2) is the last stage in the geological evolution of the island and has suffered 8 volcanic eruptions in the last 500 years, the last one in 1971. Among geochemical methods for geothermal exploration, soil gas surveys are useful for delineating main upflow regions and areas of increased subsurface permeability related to high temperature hydrothermal activity at depth. Soil gas Rn surveys are particularly useful since it is a naturally occurring radioactive gas present in geofluids that may serve as a subsurface tracer of geothermal reservoirs. An intensive soil gas was carried out from June to September 2019 in order to study the potential geothermal resource in Cumbre Vieja and the presence of vertical permeability structures related to high temperature hydrothermal reservoirs. A total of 1200 samples were taken with an average distance between sites of ≈250 m. Soil gas Rn-222 activity were measured by means of a portable SARAD RTM 2010-2 radon monitor; the instrument pumped gas through a stainless steel probe inserted at 40 cm depth and measured the Rn activity by electrostatic detection of the positively charged daughter isotopes. The soil gas Rn values ranged from atmospheric levels to 8.7 kBq m-3, with an average of 1.5 kBq m-3. The spatial distribution of soil Rn displays enrichments along the three main volcanic-rift zones: N-S, N-W and N-E, and confirms a strong structural control in the degassing processes of the volcano. The three volcanic-rift areas are zones of enhanced permeability for deep gas migration and preferential routes for degassing. It is worth noting the presence of an important soil gar Rn anomaly located at the eastern part of Cumbre Vieja, out of the three volcanic-rift areas. The data presented here are important to  identify  main  upflow  regions  and  areas  of  increased  and  deep  permeability at Cumbre Vieja.

How to cite: Pitti-Pimienta, L., Weidner, A., Shah, R., McClintock, R. L., Martín-Lorenzo, A., Rodríguez-Pérez, C., Padrón, E., Asensio-Ramos, M., Hernández, P. A., Rodríguez, F., and Pérez, N. M.: Geothermal prospecting at Cumbre Vieja volcano (La Palma, Canary Islands) by ground radon and thoron measurements , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11305, https://doi.org/10.5194/egusphere-egu2020-11305, 2020.

EGU2020-11845 | Displays | ERE2.6

Soil gas physical-chemistry survey for geothermal exploration at Terceira Island, Azores.

Claudia Rodríguez-Pérez, Alba Martín-Lorenzo, Fátima Rodríguez, Gladys V. Melián, María Asensio-Ramos, João C. Nunes, Rita A. S. Martins, Maria do Rosário Carvalho, and Nemesio M. Pérez

Terceira Island is located in the Azores Archipelago and it lies at the intersection of four submarine volcanic ridges. Due to its characteristics the geothermal potential of Terceira Island has begun to receive some interest from researchers and decision makers from the 70s of last century, but only in 2000 an exploration license was granted in favour of GEOTERCEIRA (now EDA RENOVÁVEIS S.A.). The area of this license is located in the central part of the island in the Pico Alto Volcanic Complex, and includes the fumarolic field of Furnas do Enxofre.

The main aim of this study is to provide additional information about the presence of fluids upflow regions and areas of increased subsurface permeability related to high temperature hydrothermal activity at depth, as part of an study to expand the current geothermal plant of Terceira. To achieve this objective, a soil gas and diffuse CO2 and H2S degassing survey, which included in situ CO2 emission measurements and soil temperature at 15 and 40 cm deep and the collection of soil gas samples, was performed during September 2019. 122 sampling sites were selected spaced at ~100 meters at Pico Alto Volcanic Complex. Diffuse CO2 and H2S measurements were performed according to the accumulation chamber method, using a non-dispersive infrared (NDIR) LICOR-830 CO2 analyser and ALPHASENSE H2S-BH detectors, respectively. In addition, soil gas samples were collected to analyse the He, H2, O2, N2, CO2, CH4 and CO contents and the isotopic composition of the CO2. Soil CO2 efflux values ranged between non-detectable values and 56.2 g m2 d-1, with an average of 21.7 g m2 d-1. Soil H2S efflux values ranged between non-detectable values and 0.245 g m2 d-1, with an average of 0.027 g m2 d-1. The probability plot technique applied to the soil CO2 efflux data allowed to distinguish three different geochemical populations: background, intermediate and peak represented by 36.9 %, 59.8 % and 3.3 % respectively, with geometric means of 10.8, 25.4 and 50.0 g m2 d-1 respectively. The spatial distribution of soil CO2 efflux data, constructed by means of Sequential Gaussian simulations algorithm, depicted the most important emission anomalies at the western section of the study area. These results can help to identify the possible existence of additional actively degassing geothermal reservoirs to reduce the uncertainty inherent to the selection of the area with the highest potential success in the selection of new exploratory wells at Terceira.

How to cite: Rodríguez-Pérez, C., Martín-Lorenzo, A., Rodríguez, F., Melián, G. V., Asensio-Ramos, M., Nunes, J. C., Martins, R. A. S., Carvalho, M. D. R., and Pérez, N. M.: Soil gas physical-chemistry survey for geothermal exploration at Terceira Island, Azores., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11845, https://doi.org/10.5194/egusphere-egu2020-11845, 2020.

EGU2020-11962 | Displays | ERE2.6

Clustering analysis of soil gas chemical ratios as a potential geochemical tool for surface geothermal exploration

Ángel M. González-Moro, Luca D'Auria, and Nemesio M. Pérez

Geochemistry is a fundamental tool in surface geothermal exploration. In particular, the analysis of the composition of the soil atmosphere, the measurement of diffuse CO2 flux and of the gas 222Rn activity are important parameters to detect and characterize the contribution of volcanic/hydrothermal sources in the diffuse soil degassing.

The analysis of the soil atmosphere usually consists of determining the chemical and isotopic composition of the gases, including concentrations and molar ratios of multiple chemical species (e.g. He, H2, N2, Ar, Ne, O2, CH4, CO2), as well as the C isotopic ratios (13C/12C). In practice a single geochemical survey provides tens of different parameters for each sampling point. Taking into account that a typical survey is composed of hundreds of sampling points, the huge amount of collected data requires effective data mining tools to perform analyses going beyond the simple mapping of concentrations and/or ratios and to detect hidden patterns in the dataset.

Among the most effective multivariate statistical tools is clustering analysis. This technique allows determining the presence of groups of points showing a given degree of similarity. In this work we used and compared two different clustering techniques: the K-means and the DBSCAN algorithms, applying them to a geochemical dataset related to surveys realized in 2010 in the southern part of the island of Tenerife (Canary Islands Spain) with the aim of geothermal exploration. We show how the clustering analysis allows determining the presence of areas characterized by a similar chemical and isotopic composition. The use of standard geochemical tools allows interpreting the nature of these areal groups in terms of their relevance for the purposes of surface geothermal exploration.

How to cite: González-Moro, Á. M., D'Auria, L., and Pérez, N. M.: Clustering analysis of soil gas chemical ratios as a potential geochemical tool for surface geothermal exploration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11962, https://doi.org/10.5194/egusphere-egu2020-11962, 2020.

EGU2020-12923 | Displays | ERE2.6

COSEISMIQ: First results of high resolution imaging of the shallow crust and relocation of induced seismicity in the Hengill area, Iceland

Anne Obermann, Pilar Sánchez-Pastor, Alejandro Duran, Tobias Diehl, Vala Hjörleifsdóttir, and Stefan Wiemer

For the future development of deep geothermal energy exploitation in Europe, large magnitude induced seismic events are an obstacle. On the other hand, the analysis of induced microseismicity allows to obtain the spatial distribution of fractures within the reservoir, which can help, not only to identify active faults that may trigger large induced seismic events, but also to optimize hydraulic stimulation operations and to locate the regions with higher permeability, enhancing energy production. The project COSEISMIQ (COntrol SEISmicity and Manage Induced) integrates seismic monitoring and imaging techniques, geomechanical models and risk analysis methods with the ultimate goal of implementing innovative tools for the management of the risks posed by induced seismicity and demonstrate their usefulness in a commercial scale application in Iceland.

Our demonstration site is the Hengill region in Iceland. The Hengill volcanic complex is located in SW Iceland on the plate boundary between the North American and Eurasian plates. In this region, the two largest geothermal power plants of Iceland are currently in operation, the Nesjavellir (120MW electricity) and the Hellisheidi (300MW electricity) power stations. In October 2018, we densified the permanent seismic network run by ISOR and IMO in this area (14 stations) with 23 broadband seismic stations.

We present the project and show first results from high resolution imaging of the shallow crust with ambient seismic noise, as well as first results from the relocated seismic events. The ambient noise imaging highlights an area of low seismic velocity close to the Þingvallavatn Lake, characteristic for the presence of supercritical fluids. The main geothermal production area is located as well in a low velocity zone that reaches 200 meters depth below Hellisheidi and around 700 meters below Nesjavellir.

 

How to cite: Obermann, A., Sánchez-Pastor, P., Duran, A., Diehl, T., Hjörleifsdóttir, V., and Wiemer, S.: COSEISMIQ: First results of high resolution imaging of the shallow crust and relocation of induced seismicity in the Hengill area, Iceland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12923, https://doi.org/10.5194/egusphere-egu2020-12923, 2020.

EGU2020-13276 | Displays | ERE2.6

Estimation of subsurface formation temperature in the Upper Yangtze Area, Southwest China

Xianglan Li, Shaowen Liu, and Ming Xu

Subsurface formation temperature in the upper Yangtze area, southwest China, is significant for assessment of hydrocarbon generation and preservation, especially that of shale gas. The upper Yangtze area, with well-developed marine carbonate rocks, is one of the important preferred areas of shale gas exploration and development in China. Previous studies have analyzed the accumulation mechanism, development characteristics, hydrocarbon generation potential and occurrence modes of shale gas. However, the analysis of subsurface formation temperature is rare due to a lack of highly accurate temperature data. Here we combined new steady-state temperature logging data, drill-stem test temperature data and measured rock thermal properties, to investigate the geothermal regime and to estimate the formation temperature at specific depths in the range 1000~6000 m in this area.

Our results show that the present-day geothermal gradient for this area ranges from 10 to 74℃/km, with a mean of 24℃/km; While the heat flow varies from 27 to 118mW/m2, with a mean of 64mW/m2, indicating a moderate-high geothermal regime. Formation temperature at the depth of 1000 m is estimated to be between 26 °C and 71°C, with a mean of 40°C; the temperature at 2000 m ranges from 36~125°C with an average of 64°C; 45~180°C is for that at the depth of 3000 m, and the mean is 88°C; the temperature at 4000 m varies from 88 to 235°C, with a mean of 112°C; 65~290°C is for that at 5000 m depth, with a mean of 136°C; 75~344°C is for that at the depth of 6000 and the mean is 160°C. Generally, the pattern of the estimated subsurface temperatures in different depths is similar and has an obvious sub-area characterization, showing a trend of gradually increasing of temperature from northeast to southwest area. Most areas in the south and southeast of Sichuan Basin are with moderate temperature area, which maybe is the “sweet spot area” for shale gas exploration.

How to cite: Li, X., Liu, S., and Xu, M.: Estimation of subsurface formation temperature in the Upper Yangtze Area, Southwest China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13276, https://doi.org/10.5194/egusphere-egu2020-13276, 2020.

EGU2020-13510 | Displays | ERE2.6

Evaluating thermal losses and storage capacity in high-temperature aquifer thermal energy storage (HT-ATES) systems with well operating limits: insights from a study-case in the Greater Geneva Basin, Switzerland

Marine Collignon, Øystein Klemetsdal, Olav Møyner, Marion Alcanié, Antonio Rinaldi, Halvor Nilsen, and Matteo Lupi

High temperature aquifer thermal energy storage (HT-ATES) can play a key role for a sustainable interplay between different energy sources and in the overall reduction of CO2emission. In this study, we numerically investigate the thermo-hydraulic processes of an HT-ATES in the Greater Geneva Basin (Switzerland). The main objective is to investigate how to handle the yearly excess of heat produced by a nearby waste-to-energy plant. We consider potential aquifers located in different stratigraphic units and design the model from available geological and geophysical data. Aquifer properties, flow conditions and well strategies are successively tested to evaluate their influence on the HT-ATES economic performance and environmental impact. This was achieved using a new open-access, user-friendly and efficient code that we also introduce here as a possible tool for geothermal applications.

 

The results highlight the importance of thorough numerical simulations based on more realistic exploitation when designing HT-ATES systems. We show that relations between thermal performance and the shape of the injected thermal volume are generally hard to derive when complex well schedules are imposed because the injected/produced volumes may not be equal. Despite more complex storage strategies to comply with legal regulations, the shallower group of investigated aquifers in this study remains economically more suitable for storage up to 90ºC. In average four well doublets will be required to store the yearly excess of energy. The deeper group of investigated aquifers, however, become interesting for storage at higher temperatures.

How to cite: Collignon, M., Klemetsdal, Ø., Møyner, O., Alcanié, M., Rinaldi, A., Nilsen, H., and Lupi, M.: Evaluating thermal losses and storage capacity in high-temperature aquifer thermal energy storage (HT-ATES) systems with well operating limits: insights from a study-case in the Greater Geneva Basin, Switzerland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13510, https://doi.org/10.5194/egusphere-egu2020-13510, 2020.

During June and July of 2018 St1 Deep Heat Oy (ST1DH) performed a hydraulic stimulation between 6 km and 7 km depth beneath the Aalto University campus in Otaniemi, Espoo, Finland to establish an Enhanced Geothermal System (EGS) for district heating. The area surrounding the EGS is among the most densely populated areas in Finland with downtown Helsinki located only ~6 kilometers away.

The Institute of Seismology, University of Helsinki (ISUH) monitored the stimulation using a network of surface seismic stations and geophones. ISUH operates a temporary network of 5 broadband stations recording at 250 Hz in the Helsinki and Espoo region within ~10 km of the EGS well. During the stimulation and the immediate post-stimulation stage, ISUH also operated a temporary ~100 geophone network. This network consisted of three-component 4.5 Hz PE-6/B-geophones connected to DATA-CUBE3 digitizers recording at 400 Hz. The geophones were organized in 3 large arrays consisting of ~25 stations, 3 small 4-station arrays, and 8 single stations. ISUH was also granted access to data from borehole stations installed by ST1DH. These 12 semi-permanent borehole seismometers were installed at depths between 238 m and 1620 m and registered at 500 Hz. 

Our goal is to explore the performances of the simultaneously operating surface and borehole networks in monitoring induced seismicity in an urban hard rock environment with comparatively low attenuation of seismic signals. The results can be used in planning and designing future acquisition and monitoring systems around natural laboratories in similar envrionments.

For this we analyze the induced event detection capability based on data from the surface broadband and geophone stations and compare it to the data collected by the borehole sensors. First, the regular tools used in ISUH routine automatic analysis are applied to borehole station data to form the baseline for detection capability. We then apply the same procedures to the surface data where we take advantage of the geophone arrays by utilizing beamformed stacks in order to enhance the quality of automatic detection by improving the signal-to-noise ratio (SNR) of induced events. Second, we compile statistics of the residuals of a dataset of manually refined picks and the automatic detections to evaluate systematic effects or biases.  Third, we apply a detection and picking routine from the literature to ~500 event traces recorded at a borehole station and a colocated 25 sensor array to form a consistent data base for comparison with the routine ISUH picker. We explore the detection capability of beamformed surface record stacks by evaluating the SNR and detection statistics compared to the single borehole station. We focus on the effect of the number of traces per stack and on the frequency dependent diurnal and weekly noise variations associated with the urban environment.

How to cite: Vuorinen, T., Hillers, G., and Kortström, J.: Comparison of surface and borehole seismic network performances in observing induced seismicity from a deep EGS stimulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13814, https://doi.org/10.5194/egusphere-egu2020-13814, 2020.

EGU2020-16519 | Displays | ERE2.6

A seismotectonic study and minimum 1D velocity model for the Greater Geneva Basin, Western Switzerland

Verónica Antunes, Thomas Planès, Jiří Zahradník, Anne Obermann, Celso Alvizuri, and Matteo Lupi

In the framework of the Geothermie2020 project, the canton of Geneva and the Industrial Services of Geneva (SIG) are currently developing geothermal exploration in the Greater Geneva Basin (GGB), located in south-western Switzerland and neighbouring France. Before geothermal exploration begins, it is important to investigate the ongoing seismic activity, its relationship with local tectonic features, and the large-scale kinematics of the area. Background seismicity suggest that the local tectonic structures affecting the basin may still be active. Moderate-magnitude earthquakes have been identified along the Vuache fault, a major strike-slip structure crossing the basin. In this context we deployed a dense temporary network of 20 broadband stations around and within the GGB, during ~1.5 years, and reaching a detection threshold 0.5ML

Using a new coherence-based detector (LASSIE), we detected and located 158 events in our area of interest. However, only 20 events were located in the GGB, with local magnitudes ranging from 0.7 to 2.2ML. We found no earthquakes in the Canton of Geneva where geothermal activities are taking place. We constructed a local minimum 1D velocity model with VELEST, using the recorded seismicity together with earthquakes from adjacent regions, in a total of 1263 P- and S-picks. The new velocity model allowed to relocate micro-seismic activity up to 11km depth along the main fault systems (i.e. Vuache, Cruseilles, Le Coin, and Arve) offsetting the GGB. We retrieved 8 new focal mechanisms for the area, using a combination of polarities and waveform inversion techniques (CSPS method). A stress inversion shows a tectonic deformation dominated by a quasi-pure strike-slip regime in the GGB, consistent with structural and geological data.

The study of microseismicity in a quiet sedimentary basin is challenging due to the scarce occurrence of seismic events combined with low signal-to-noise ratios and the often strong attenuation. However, the investigation of the sporadic (yet present) natural seismicity with dedicated dense networks could provide useful information about the GGB, even with a short-term experiment. We propose a newly-computed 1D velocity model that can be used in the GGB for seismic monitoring purposes throughout the geothermal project. This model can be easily improved later on, whenever more data is available. Monitoring the evolution and dispersion of the seismic-activity through the identified seismogenic areas during the geothermal project is essential. Quantifying the seismic rate in the basin before geothermal operations start will help to quantify the impact that geothermal energy extraction might have on the GGB. 

How to cite: Antunes, V., Planès, T., Zahradník, J., Obermann, A., Alvizuri, C., and Lupi, M.: A seismotectonic study and minimum 1D velocity model for the Greater Geneva Basin, Western Switzerland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16519, https://doi.org/10.5194/egusphere-egu2020-16519, 2020.

EGU2020-18126 | Displays | ERE2.6

Ground movements associated with thermal water production from the Buda Thermal Karst (Hungary) by PS-InSAR

Eszter Békési, Gyula Grenérczy, Sándor Frey, Péter Farkas, Jan-Diederik van Wees, and Peter Fokker

Interferometric Synthetic Aperture Radar has been used worldwide for investigating ground deformation due to subsurface extraction processes. However, in the Central and Eastern European region, no such studies are available so far. We present a case study for the Buda Thermal Karst demonstrating the effectiveness of satellite-based monitoring of the region. Budapest (and the whole territory of Hungary) is well-known from balneology for centuries. Thermal bathes in Budapest mainly utilize water discharging from carbonate reservoirs. Hot springs in the area are commonly located along fault zones controlling the groundwater flow systems. We investigate ground deformation in the vicinity of the Buda Thermal Karst by Persistent Scatterer time series analysis based on Sentinel-1 data for the period of 2014-2018. Results show that surface movements associated with the extraction of thermal water and groundwater recharge and discharge exist. Inverse geodetic modeling based on various deformation sources embedded in an elastic half-space is applied to infer for reservoir processes and properties and fault structures controlling fluid pathways. The modeling results are jointly interpreted with geological and hydrogeological models of the area. The satellite-based monitoring together with the modeling results allow a better understanding of the characteristics of fluid flow systems in the area and the dynamics of geothermal reservoirs under production. Such information can be of high importance for the sustainable production of thermal water in the future.

How to cite: Békési, E., Grenérczy, G., Frey, S., Farkas, P., van Wees, J.-D., and Fokker, P.: Ground movements associated with thermal water production from the Buda Thermal Karst (Hungary) by PS-InSAR, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18126, https://doi.org/10.5194/egusphere-egu2020-18126, 2020.

EGU2020-18306 | Displays | ERE2.6

A lightweight thermal modelling tool for physics-based continental heat flow interpolation

Alberto Pastorutti and Carla Braitenberg

Both energy applications, such as assessing one of the controlling factors of conductive geothermal plays, and geodynamics modelling, are influenced by the large uncertainties arising from uneven sampling of the direct observable of the Earth's thermal state, surface heat flow. Heterogeneity in structure and composition of the continental lithosphere complicate the temperature field even in stable provinces in thermal equilibrium. The measurements deviate from what simple relationships with geological and geophysical data predict, requiring more sophisticated schemes such as those based on multivariate inversion (e.g. Mather et al. 2018) and geostatistics (e.g. the similarity method employed by Lucazeau, 2019).

Recently, we aimed at assessing the performance of satellite-gravity-constrained modelling of surface heat flow [1], with the aim of employing the unparalleled spatial uniformity of global gravity models in the fill-in of sparsely sampled surface heat flow data. The model we obtained, in a test area in Central Europe, provided additional information on the lithospheric structure and revealed a satisfactory coherence with the geological features in the area and their controlling effect on the conductive heat transport. That test was based on a fit of radioactive heat production to available heat flow data, based on a misfit linearization and substitution strategy, which we have shown to be independently consistent with available heat production relationships (e.g. Hasterok and Webb, 2017). Furthermore, model validation techniques provide additional metrics on the predictability in areas devoid of heat flow measurements.

To reach those objectives, we developed a finite-difference based solver for the heat equation in conductive, stable lithosphere, relying on the assumption of steady state, 3-D heat conduction from the thermal base of the lithosphere to surface. It allows for non-homogeneous heat production and thermal conductivity, and non-flat upper and bottom boundaries. Concurrent joint forward modelling of the gravity field is also possible.
Through compromise between complexity and approximation, it was designed favouring easy and fast forward modelling, such as in assessing parameter sensitivity and performing grid searches or parameter fitting. Geological models and parameters can be defined using an user-friendly plain text layer-wise definition, which is then turned into a volume, on a rectangular mesh.
Computational requirements are lean: a 75 × 75 × 104 node model such as the one employed in [1] can be forward-modelled on an ordinary workstation in 135 seconds. A direct solver is employed to solve the FD system of linear equations: the Matlab built-in Cholesky decomposition for sparse arrays (Davis, 2006).

Albeit initially developed as an ad-hoc tool for a proof of concept, its ease of use and versatility suggest its potential in other applications. We therefore present the solver and the accompanying tool set, both openly available, along with a set of promising examples.

[1] Pastorutti, A., Braitenberg, C. (2019) "A geothermal application for GOCE satellite gravity data: modelling the crustal heat production and lithospheric temperature field in Central Europe." Geophysical Journal International, doi:10.1093/gji/ggz344

How to cite: Pastorutti, A. and Braitenberg, C.: A lightweight thermal modelling tool for physics-based continental heat flow interpolation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18306, https://doi.org/10.5194/egusphere-egu2020-18306, 2020.

EGU2020-18395 | Displays | ERE2.6

Testing Ambient-Noise Tomography as a Geothermal Exploration Method in Switzerland

Thomas Planès, Anne Obermann, Verónica Antunes, and Matteo Lupi

Switzerland is strongly promoting the development of geothermal energy extraction from low- to high-enthalpy resources. However, the broad development of geothermal energy exploitation is hindered by the lack of subsurface knowledge and the high cost of traditional subsurface exploration methods. Affordable passive seismic methods may provide valuable information about the geological structures targeted for geothermal energy extraction. In this context, we are investigating the potential of the Ambient-Noise Tomography (ANT) technique. We present past results obtained from surface-wave ANT in the Geneva basin with a sparse seismic network, and we share preliminary insights from the starting PSIGE project aiming to try refracted P-wave ANT on dense nodal networks (~500 nodes) at several Swiss geothermal exploration sites. From synthetic examples based on prior subsurface models, we discuss the expected depth of investigation and potential resolution of the method with various network configurations. 

How to cite: Planès, T., Obermann, A., Antunes, V., and Lupi, M.: Testing Ambient-Noise Tomography as a Geothermal Exploration Method in Switzerland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18395, https://doi.org/10.5194/egusphere-egu2020-18395, 2020.

EGU2020-19190 | Displays | ERE2.6

The Heat beneath Our Feet

Jeroen van Hunen, Charlotte Adams, Jon Gluyas, Jonty de la Harpe, Karina Hastie, and Tom Norman

While coal energy is phased out to decarbonise our energy supply, the water within flooded abandoned mines provide a huge source (2.2 million GWh) of geothermal heat for the future, enough to meet the UK’s heating demand for more than a century. The mine water is only lukewarm (12-20oC), but by using a heat pump, temperatures can be increased to a more comfortable 40-50oC. Heat pumps need electricity, but for every kW of electrical input, the heat output is 3-4 kW, making this an efficient energy source. Research has shown that our abandoned mines could meet our heat demands for a century or more, and will deliver economic opportunities to former mining areas.

After abstraction of water from the mine and subsequent heat extraction , the mine water is returned to the subsurface to avoid surface water contamination. Understanding the subsurface to ensure the right location(s) for re-injection of the water is crucial for the thermal evolution of the mine system. In addition, mine water could interact with nearby (potable) aquifers, so a proper understanding of the hydrogeological behaviour of the mined system is required. Therefore, numerical modelling of mine water and surrounding groundwater flow and associated heat exchange is an essential first stage for the successful deployment of these geothermal mine energy systems.

Here, we present numerical modelling results of the thermal evolution of mine water circulation systems. A parameter sensitivity study gives insight in the rate of heat depletion of the mines, and the importance of several model parameters, such as mine tunnel connectivity, mine water flow speed, and water re-injection location.

This project involves collaboration with the Coal Authority and Durham county council in the UK. Available mine plan data offer opportunities to apply the modelling to proposed mine energy sites across coalfields in the UK and further afield. Results will be applied for planned geothermal energy sites at Stanley (county Durham), South Tyneside and Blyth Port in north-east England.

How to cite: van Hunen, J., Adams, C., Gluyas, J., de la Harpe, J., Hastie, K., and Norman, T.: The Heat beneath Our Feet, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19190, https://doi.org/10.5194/egusphere-egu2020-19190, 2020.

EGU2020-20541 | Displays | ERE2.6

Feasibility, Design and authorization of a zero-emission Geothermal Power Plant in Italy; Case Study: “Montenero” Project

Paolo Basile, Roberto Brogi, Favaro Lorenzo, and Tiziana Mazzoni

Social consensus is a condition precedent for any intervention having an impact on the territory, such as geothermal power plants. Therefore, private investors studied and proposed innovative solution for the exploitation of the medium enthalpy geothermal resource, with “zero emissions” in atmosphere, with the target of minimizing its environmental impact. “Montenero” project, developed by GESTO Italia, complies with this precondition.

The area covered by the exploration and exploitation permit is located on the northern edge of the great geothermal anomaly of Mt. Amiata (Tuscany), about 10 km north of the geothermal field of Bagnore, included in the homonymous Concession of Enel Green Power.

The geological - structural setting of the area around the inactive volcano of Mt. Amiata has been characterized by researches for the geothermal field of Bagnore, carried out by Enel Green Power over the years. The geothermal reservoir is present in the limestone and evaporitic rocks of the “Falda Toscana”, below which stands the Metamorphic Basement, as testified by the wells of geothermal field of Bagnore. The foreseen reservoir temperature at the target depth of 1.800 m is 140 °C, with an incondensable gas content of 1,8% by weight.

The project was presented to the authorities in 2013 and it is now undergoing exploitation authorization and features the construction of a 5 MW ORC (Organic Ranking Circle) binary power plant. The plant is fed by three production wells for a total mass flow rate of 700 t/h. The geothermal fluid is pumped by three ESPs (Electrical Submersible Pump) keeping the geothermal fluid in liquid state from the extraction through the heat exchangers to its final reinjection three wells.

The reinjection temperature is 70 °C and the circuit pressure is maintained above the incondensable gas bubble pressure, i.e. 40 bar, condition which prevents also the formation of calcium carbonate scaling. The confinement of the geothermal fluid in a “closed loop system” is an important advantage from the environmental point of view: possible pollutants presented inside the geothermal fluid are not released into the environment and are directly reinjected in geothermal reservoir.

The environmental authorization procedure (obtained) has taken into account all the environmental aspects concerning the natural matrices (air, water, ground, ...) potentially affected by the activities needed for the development, construction and operation of “Montenero” ORC geothermal power plant. A numerical modeling was designed and applied in order to estimate the effect of the cultivation activity and to assess the reinjection overpressure (seismic effect evaluation). The project also follows the “best practices” implemented in Italy by the “Guidelines for the usage of medium and high enthalpy geothermal resources” prepared in cooperation between the Ministry of Economic Development and the Ministry of the Environment.

How to cite: Basile, P., Brogi, R., Lorenzo, F., and Mazzoni, T.: Feasibility, Design and authorization of a zero-emission Geothermal Power Plant in Italy; Case Study: “Montenero” Project, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20541, https://doi.org/10.5194/egusphere-egu2020-20541, 2020.

The GeoTief EXPLORE project aims to explore the geothermal potential and quantify the geothermal resources of the Vienna Basin (Austria) and the underlying Northern Calcareous Alpine basement. The main target of geothermal interest is the massive and tectonically remolded Hauptdolomite facies that has been identified as potential geothermal reservoir in previous studies. Now, this formation is studied using outcrop analogues for the investigation of their petrophysical characterization and specific thermal properties (thermal conductivity and thermal diffusivity).

 

Here, we report new measurements on a total of 60 samples from 6 outcrops in and around the area of Vienna applying different methods for the laboratory measurement of thermal and hydraulic rock properties. The petrophysical analysis considers the impact of deformation along and across fault zones, which introduces heterogeneity of storage properties and consequently in the thermophysical properties. Using the standard fault core and damage zone model, outcrop samples were grouped into unfractured and fractured protoliths, as well as in fault rocks, like breccias and cataclasites. Rock samples are then classified by their fracture density (m² fracture surface per m³ rock) and by their matrix content and differences in grain sizes, respectively.

 

The measured thermal rock properties vary significantly between the selected rock groups. The total range [90 % of values] is between 3.2 and 5.0 W/(mK) for thermal conductivity and between 1.3 and 2.7 mm²/s for thermal diffusivity. The results generally met the expected trend for fractured rocks as conductivity and diffusivity decreases with increasing porosity under unsaturated and saturated conditions. The total porosities are less than 5%. The variability of thermal conductivity under saturated conditions shows complex trends depending on the different rock classifications where fault rocks and highly fractured rocks of the damage zone show lower increase in thermal conductivities.

 

The new petrophysical characterization will be the base for further numerical investigations of the hydraulic and thermal regime as well as for the analysis of the geothermal resources of the Hauptdolomite.

 

 

 

 

How to cite: Rupprecht, D., Fuchs, S., Förster, A., and Penz-Wolfmayr, M.: Thermophysical reservoir properties of the Hauptdolomit-facies underneath the Viennese basin across fault zones analogues – a reservoir study for the GeoTief EXPLORE project , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21332, https://doi.org/10.5194/egusphere-egu2020-21332, 2020.

EGU2020-21618 | Displays | ERE2.6

Investigation of the geological, technical and economical obstacles for large-scale utilization of geothermal energy from Danish sandstone reservoirs

Mette Olivarius, Niels Balling, Jesper P. M. Baunsgaard, Esben Dalgaard, Hanne Dahl Holmslykke, Anders Mathiesen, Troels Mathiesen, Henrik Vosgerau, Rikke Weibel, and Lars Henrik Nielsen

The Triassic–Jurassic sandstone reservoirs in the Danish subsurface at c. 1–3 km depth contain an enormous geothermal resource that is currently utilized in only three geothermal plants due to a number of geological, technical and commercial barriers. These barriers have been addressed in the GEOTHERM project funded by Innovation Fund Denmark and recommendations for overcoming the obstacles have been made. Some of the methods that are used in the oil and gas sector have successfully been introduced in the geothermal reservoir evaluations to reduce the risk associated with new exploration wells. Quantitative seismic interpretation proved capable of giving a reliable reservoir characterization with regards to estimation of porosity and sand/clay distribution. Diagenesis modelling gave good estimates of reservoir quality by utilizing the knowledge obtained about depositional environments, petrography, reservoir properties and burial history. Relationships between fluid and gas permeability have been established such that the regularly measured gas permeability can be recalculated to fluid permeability giving a better representation of the reservoir. The composition of the formation water in the three geothermal plants has been measured and used for geochemical modelling to evaluate the risk of scaling, where especially barite showed a tendency to precipitate upon cooling of the brine. Simulations of the thermal development of the reservoirs during long-term geothermal exploitation demonstrate significant heat extraction from the layers present above and below each reservoir, which ensures that only a small decrease in production temperature occurs over several decades. The regional geothermal resource estimation has been updated based on a new comprehensive 3D temperature model of the subsurface, confirming the presence of a huge geothermal resource with wide geographical extend covering most of the country. The causes of injection problems have been investigated including corrosion and scaling processes, showing that careful choice of well-lining and tubing materials besides cautious operation of plants are of utmost importance to prevent problems. A geothermal business case has been developed to give a lifetime assessment of geothermal plants including feasibility, design, drilling, construction, production and abandonment, showing that the operational costs are closely linked to the existing infrastructure and to the choices made when designing the geothermal plant. In conclusion, the new scientific results and best-practice manuals provide a significantly higher chance of success of new geothermal projects when including the recommended measures to minimize the geological uncertainties and prevent problems during drilling and production.

How to cite: Olivarius, M., Balling, N., Baunsgaard, J. P. M., Dalgaard, E., Holmslykke, H. D., Mathiesen, A., Mathiesen, T., Vosgerau, H., Weibel, R., and Nielsen, L. H.: Investigation of the geological, technical and economical obstacles for large-scale utilization of geothermal energy from Danish sandstone reservoirs, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21618, https://doi.org/10.5194/egusphere-egu2020-21618, 2020.

ERE2.7 – Characterization and modeling of (coupled) THMC processes for geothermal energy

EGU2020-417 | Displays | ERE2.7

Barite scaling in fractures simulated with nucleation and crystal growth kinetics

Morgan Tranter, Marco DeLucia, and Michael Kühn

Deep hydrothermal systems in fractured media are a potential source of geothermal energy. A key problem prevails as a consequence of utilisation that the geochemical system is perturbed and scaling may build up over time. Barite stands out as one of the most ubiquitous scaling agents in deep geothermal systems. It causes irreversible efficiency loss and may be responsible for geothermal power plants to become non-profitable. Due to complex parameter interplay and underlying uncertainties, it is imperative to utilise numerical simulations to investigate temporal and spatial precipitation effects.
In this work, the impact on fracture permeability in the near field of the injection well is assessed. A one-dimensional reactive transport model is set up with heterogeneous nucleation and crystal growth kinetics. In line with potential target hydrothermal systems in the North German Basin, the following parameters are considered in a sensitivity analysis: injection temperature (50 to 70 °C), pore pressure (10 to 50 MPa), fracture aperture (10-4 to 10-2 m), flow velocity (10-3 to 100 m s-1), molar volume (50.3 to 55.6 cm3 mol-1), contact angle for heterogeneous nucleation (0° to 180°), interfacial tension (0.07 to 0.134 J m-2), salinity (0.1 to 1.5 mol kgw-1 NaCl), pH (5 to 7), and supersaturation (1 to 30).
Nucleation and consequently crystal growth can only begin if the threshold supersaturation is exceeded. Therefore, contact angle and interfacial tension are the most sensitive in terms of precipitation kinetics. If nucleation has occurred, crystal growth becomes the dominant process, which is mainly controlled by fracture aperture. Results show that fracture sealing can happen within months (33 days) and the affected range can be in the order of tens of metres (10 m). Predicting the threshold supersaturation is a crucial point in this context, as it essentially determines if barite precipitation becomes relevant.
The uncertainty of parameters influencing nucleation at in-situ conditions is high, emphasising the need to investigate these in more detail. The presented models suggest that barite scaling must be recognised as a serious threat if the supersaturation threshold is exceeded, in which case, larger fracture apertures could help to minimise kinetic rates.

How to cite: Tranter, M., DeLucia, M., and Kühn, M.: Barite scaling in fractures simulated with nucleation and crystal growth kinetics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-417, https://doi.org/10.5194/egusphere-egu2020-417, 2020.

EGU2020-5998 | Displays | ERE2.7

Study of heat extraction and flow process by fully coupled thermal- hydro- mechanical model

Dejian Zhou, Alexandru Tatomir, and Martin Sauter

Enhanced Geothermal Systems (EGS) are widely used in the development and application of geothermal energy. They usually consist of two parallel deep boreholes, where cold water is injected into one borehole and abstracted at the second one after being heated when passing through the fractured network system. Recently, simple analytical solutions have been proposed to estimate the water pressure at the output. Nevertheless, these methods do not take into account the influences of the coupled thermal and mechanical processes. In this research study we build a fully coupled Thermal – Hydro-mechanical model (THM model) to simulate the processes of heat extraction, deformation and water flow in the nearby fractured rock formations. The influences of single thermal – hydraulic and mechanical – hydraulic effects were compared with the fully coupled and decoupled results, showing that temperature influences mostly the water pressure in the second borehole, compared with temperature. The mechanical effect alone has little influences on the water pressure. A sensitive analysis was also conducted to study which parameters affect the simulation results the most. It was shown that the initial permeability and temperature are playing the main roles in this simulation.

How to cite: Zhou, D., Tatomir, A., and Sauter, M.: Study of heat extraction and flow process by fully coupled thermal- hydro- mechanical model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5998, https://doi.org/10.5194/egusphere-egu2020-5998, 2020.

EGU2020-10065 | Displays | ERE2.7

Geothermal modelling in fault zones with the CIMLIB/EXALIB library

Jacques Dentzer, Elie Hachem, Patrick Goblet, Olivier Stab, and Dominique Bruel

Energy transition requires the use of low-carbon energies such as geothermal energy for the production of electricity or heat. Geothermal exploitation has a number of preferential targets, including fault zones in the context of graben. High temperatures can, indeed, be observed where fluids rise through fault zones, but geothermal processes are complex to understand and to model in such a 3D tectonic context. For instance, seismic observations and then observations at well-scale show structures on different spatial scales that can overlap and interconnect. These structures then present strong heterogeneities in physical properties (e.g. fault core or damage zones). In addition, this knowledge evolves over time, from the exploration to drilling and exploitation phases. One of the challenges of numerical modelling is to represent this complexity while being readily upgradeable in the light of exploration. We are developing an adaptive approach using the CIMLIB/EXALIB library. Geometrical complexity and physical properties are defined by distance functions (level set functions) to geologic objects that are inherited from a geologic modelling software. Coupled fluid flow and heat transport processes are then modelled in 3D with adaptive meshing. The mesh can, indeed, be adapted according to static criteria such as geometry or dynamic criteria such as physical processes. This approach will be illustrated by examples derived from an ongoing GIS-Geodenergies project in the Upper Rhine Graben.

How to cite: Dentzer, J., Hachem, E., Goblet, P., Stab, O., and Bruel, D.: Geothermal modelling in fault zones with the CIMLIB/EXALIB library, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10065, https://doi.org/10.5194/egusphere-egu2020-10065, 2020.

EGU2020-11017 | Displays | ERE2.7

Seismic models of the Los Humeros caldera (Mexico) using the GEMEX project data

Marco Calò, Angel Figureoa Soto, Stephani Cruz-Hernandez, Ivan Granados Chavarría, Brenda De la Rosa, Joel Angulo Carrilo, Tania Toledo, Emmanuel Gaucher, and Philippe Jousset

In the framework of the GEMEX project (cooperation between Europe and Mexico for geothermal development), a dense network of 45 stations was deployed in 2017-2018 in the Los Humeros caldera, Mexico.

Thanks to this network an intense local seismic activity has been recorded in the geothermal field and surroundings, from which it has been possible to identify high-frequency Volcano-Tectonic events (VT, >10 Hz) and Long-Period events (LP, 1-8 Hz). The former set of events is mainly associated with the local tectonics and power plant activities; while the latter has been generally recorded after strong earthquakes (Mw>7) occurred in Mexico.

Consequently, we adapted and applied two tomographic techniques to generate highly resolved seismic models; 1) the Enhanced Seismic Tomography (EST) method using the travel times of local seismic events. The method incorporates the Double Difference tomography and the post-processing Weighted Average Method to generate Vp and Vs models, and 2) the surface wave tomography method based on ambient noise analysis. In this case, we generated 3D anisotropic models of phase and group velocities of the Rayleigh and Love waves from Green functions retrieved by cross-correlation of the continuous records.

Thanks to the severe pre-processing of the whole seismic database that allowed to correct several errors on the data, and to the methods applied, we were able to obtain reliable and highly resolved models with both techniques.

Finally, the two sets of events (VT and LP) have been relocated using the 3D seismic velocity models of the region in order to better characterize the structure of the geothermal field and identify regions where the fluids could have a role on the triggering of the LP seismic activity observed.

This work is performed in the framework of the Mexican European consortium GeMex (Cooperation in Geothermal energy research Europe-Mexico, PT5.2 N: 267084 funded by CONACyT-SENER: S0019, 2015-04, and Horizon 2020, grant agreement No. 727550).

How to cite: Calò, M., Figureoa Soto, A., Cruz-Hernandez, S., Granados Chavarría, I., De la Rosa, B., Angulo Carrilo, J., Toledo, T., Gaucher, E., and Jousset, P.: Seismic models of the Los Humeros caldera (Mexico) using the GEMEX project data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11017, https://doi.org/10.5194/egusphere-egu2020-11017, 2020.

EGU2020-12544 | Displays | ERE2.7

3D Anisotropic velocity model of the Los Humeros geothermal field, Mexico, using seismic ambient noise tomography.

Ivan Granados Chavarria, Marco Calò, Ángel Figueroa Soto, and Philippe Jousset

In the framework of the international collaboration between Mexico and Europe for the development of geothermal energy (GEMex consortium), a seismic network of 45 seismic stations (25 broad-band and 20 short-period) was installed around the super-hot geothermal system of Los Humeros (Mexico) for more than one year. Los Humeros power plant is nested inside a quaternary caldera located in the eastern part of the Trans-Mexican Volcanic Belt that crosses the whole country from the Pacific coast to the Gulf of Mexico.

Among the several targets of the data collected by this network, an important task is to produce a seismic image of the caldera and of the geothermal reservoir. Here we present the 3D anisotropic shear wave velocity models retrieved by the seismic ambient noise tomography.

Thanks to the severe pre-processing of the whole seismic database we were able to obtain reliable and highly resolved models.

To carry out the model we applied a rigorous data quality assessment consisting in: 1) correction of the orientation of the sensors using the polarization of surface waves associated with tele-seismic and regional earthquakes, 2) assessment of the synchronization of the stations and correction of the times using daily cross-correlations functions, 3) finally to asses the quality of the stacked cross-correlations, knowed as Green’s functions (GF), we analyzed the noise sources directivity, inter-station distance and level of emergence of surface waves depending on the type of sensor used.

The processing allowed to pick clearly about 600 dispersion curves per velocity type (group and phase of R and L waves), using the NDCP code (Noisy Dispersion Curve Picking), that allows to display and select dispersion patterns both in time and frequency domain, for both causal and anti-causal part of the GF.

2D tomography maps were calculated from 0.5 to 9 s for each type of velocity. Depth inversion for the whole velocities types was carried out using surf96, allowing reconstructing the 3D anisotropic structure of the caldera for the first time.

The resulting models provides a larger view of the caldera and its anisotropic patterns down to 10 km depth. In these models, we were able to define the depth of the caldera rim, some important features of the internal part of the caldera and a low velocity body that could be associated with the hot sources feeding the reservoir. Our model are in strong agreement with those retrieved applying other geophysical methodologies (e.g. magnetotelluric, passive travel-time tomography, gravimetric, etc.).

This work is performed in the framework of the Mexican European consortium GeMex (Cooperation in Geothermal energy research Europe-Mexico, PT5.2 N: 267084 funded by CONACyT-SENER : S0019, 2015-04, and Horizon 2020, grant agreement No. 727550).

How to cite: Granados Chavarria, I., Calò, M., Figueroa Soto, Á., and Jousset, P.: 3D Anisotropic velocity model of the Los Humeros geothermal field, Mexico, using seismic ambient noise tomography., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12544, https://doi.org/10.5194/egusphere-egu2020-12544, 2020.

EGU2020-13699 | Displays | ERE2.7

Numerical strategies for characterizing fractured rock from heat tracer experiments

Delphine Roubinet, Zitong Zhou, and Daniel Tartakovsky

Characterization of fractured rocks is a key challenge for optimizing heat harvesting in geothermal systems. The use of heat as a tracer, facilitated by the development of such advanced techniques as active line source (ALS) borehole heating and the distributed temperature sensing (DTS), shows the great potential for characterizing fractured rocks. However, there is so far a limited number of theoretical and numerical studies on how these tests could be used for estimating both fracture-network and rock-matrix properties.

We use deep neural networks to describe heat tracer test data and demonstrate how the cumulative density function (CDF) or probability density function (PDF) of the heat tracer test data can be deployed in the inversion mode, i.e., to infer the fracture parameters with. Our approach utilizes the methods of distributions, developed previously to estimate the CDF of solute concentration described by a reactive transport model with uncertain parameters and inputs. The method is applied to analyze several synthetic heat tracer test datasets obtained from a particle-based forward model of transport processes in heterogeneous fractured rocks. The study considers alternative representations of fracture networks with a large range of variation of the fracture network properties, as well as several experimental conditions (e.g., ambient/forced thermal and hydraulic conditions, pulse/continuous changes in temperature). This allows us to characterize the system by combining the information from several thermal tests.

How to cite: Roubinet, D., Zhou, Z., and Tartakovsky, D.: Numerical strategies for characterizing fractured rock from heat tracer experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13699, https://doi.org/10.5194/egusphere-egu2020-13699, 2020.

Abstract: Hydraulic fracturing process is invisible in geological media and is difficult to be observed. The acoustic emissions (AEs) or microseismic (MS) technologies are useful approaches to estimate the hydraulic fracturing process. However, the AEs or MS do not provide the geometry of hydraulic fractures directly, but only provides the coordinates of AEs/MS sources. Traditional analytical and statistical approaches of reproducing fracture geometry using AEs/MS sources are relatively empirical. In this work, we monitored the AEs induced by hydraulic fracturing experimentally. Then, data-driven simulation based inverse analysis approach is developed to estimate the fracture geometry according to AEs sources. The difference between hydraulic fractures and AEs sources is defined as objective function. Then, the in-situ stresses are found using the inverse analysis based on data-driven simulation. As shown in Fig. 2, the geometry of hydraulic fractures is reproduced using data-driven simulation and AEs technology.

Keywords: hydraulic fracturing, inverse analysis, data-driven simulation, acoustic emissions technology, AiFrac

How to cite: Dai, H. and Tang, X.: Inverse analysis of hydraulic fracture geometry based on data-driven simulation and acoustic emissions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18177, https://doi.org/10.5194/egusphere-egu2020-18177, 2020.

EGU2020-20114 | Displays | ERE2.7

Reactive Flow Model for Porosity Reduction by Quartz Dissolution/Precipitation

Batoul Gisler and Stephen A. Miller

Quartz dissolution and precipitation is an important pore reducing process in geothermal reservoirs. We present a single-phase reactive flow model coupled with hydrodynamic flow and heat transfer components and implement it into COMSOL Multiphysics. The model includes diffusion and advection, and analytical equations are used to describe quartz kinetics and equilibrium concentrations with respect to the silicate phases. The numerical model can a priori be used to analyze the evolution of the porosity/permeability, and hence the productivity of the reservoir induced by heat extraction in geothermal reservoirs. A geothermal reservoir is modeled with realistic time steps, where its geometry is represented as a porous medium block in which chemical reactions occur between the pore fluid and the rock matrix. Future developments include adding a fracture and fracture networks to the system and analyzing the changes in effective stresses in the presence of reactive flow. Economic reservoir development requires a combined analysis of the thermo-hydro-mechanical and chemical processes, and precipitation processes may be important in post-seismic fluid flow processes.

How to cite: Gisler, B. and A. Miller, S.: Reactive Flow Model for Porosity Reduction by Quartz Dissolution/Precipitation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20114, https://doi.org/10.5194/egusphere-egu2020-20114, 2020.

EGU2020-20902 | Displays | ERE2.7

Feasibility of Radial Borehole Fracturing in Geothermal Exploitation: an Experimental Study

Shouceng Tian, Zhaoquan Guo, Yuqi Sun, Qisheng Wang, Qingling Liu, Mao Sheng, and Zhonghou Shen

Enhanced geothermal system (EGS) is an important way of geothermal development, which takes advantage of the fractures serving as the channels of working fluid flow and heat transfer. But constrained by the geometries of hydraulic fractures formed through conventional fracturing technologies, the heat transfer areas are limited. Radial borehole fracturing combines hydraulic fracturing and radial boreholes which extend to the formation radially from 10 to 100 meters and have diameters of 20 to 50 millimeters. This paper aims to investigate whether radial borehole fracturing can increase the fracture areas in EGS system comparing with perforation fracturing. 
Nine cubic concretes (300*300*300mm) were cast after mixing sand, cement and water. Six of them contained radial boreholes and three had perforations. All cubic concretes were heated to 200℃ and fractured by a tri-axial fracturing test system with injection rates of 30ml/min and horizontal principal stress differences being 6 MPa. Then the fractures were scanned and the fracture areas were calculated. Three different angles between radial boreholes/perforations and maximum horizontal stress (0°, 45°, 90°) and two quantities of radial boreholes (2, 4) were studied. 
Experimental results show that radial borehole fracturing creates greater fracture areas then that of perforation fracturing if the orientations of radial boreholes and perforations do not consist with the direction of maximum horizontal stress. Because the fractures turn to the direction of maximum horizontal stress more quickly for perforation fracturing when perforations and radial boreholes have identical angles, namely radial boreholes guide the fractures better as they extend into the concretes. Besides, concretes with 4 radial boreholes have smoother fractures than concretes with 2 radial boreholes. In addition, the breakdown pressure of radial borehole fracturing is lower and increasing the quantities of radial boreholes reduces the breakdown pressure. 
This experimental investigation reveals that radial borehole fracturing can form larger fracture areas than perforations fracturing, which promotes the efficiency of heat extraction in EGS system.

How to cite: Tian, S., Guo, Z., Sun, Y., Wang, Q., Liu, Q., Sheng, M., and Shen, Z.: Feasibility of Radial Borehole Fracturing in Geothermal Exploitation: an Experimental Study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20902, https://doi.org/10.5194/egusphere-egu2020-20902, 2020.

EGU2020-21313 | Displays | ERE2.7

Simulating cryogenic fracturing process with TOUGH-FEMM

Haiyang Zhao and Zhiyuan Liu

The dry hot rock (DHR) is a widely distributed renewable and clean energy. Cryogenic fracturing, such as liquid nitrogen fracturing technology, in DHR not only avoids the consuming of water, but also enhances the fracturing with the rock damage induced by thermal stress. During fracturing, cryogenic fluid (extremely low temperature) is utilized to trigger sharp a thermal gradient and fracturing surrounding boreholes, which generates fracture networks and increase the permeability of DHR. In this work, the TOUGH-FEMM simulator, which links the TOUGH2 thermal-hydraulic simulator and a mechanical simulator based on hybrid the finite-element meshfree method (FEMM), is developed to model three-dimensional cracking induced by cryogenic injection. The results of the numerical simulations agree with the experimental results showing that the fracture network is generated and connected to the borehole. An increased connectivity between a production borehole and the fracture network can significantly enhance fluid and hydro carbon production.

How to cite: Zhao, H. and Liu, Z.: Simulating cryogenic fracturing process with TOUGH-FEMM, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21313, https://doi.org/10.5194/egusphere-egu2020-21313, 2020.

ERE2.8 – Shallow geothermal systems for building heating and cooling: geoscience and engineering approaches

EGU2020-584 | Displays | ERE2.8

Elaboration of charts based on geometry variations for the design of thermo-active piles

Mila Smiljanovska, Hussein Mroueh, Julien Habert, and Josif Josifovski

Contemporary living, the extreme climate changes and the necessity of renewable energy sources challenge the engineers around the globe to discover advanced methods of enabling a more comfortable life. For this purpose, geothermal energy systems are used to satisfy the calorific needs for cooling and heating. Thermo-active geo-structures, as dual-function elements, offer structural improvement and simultaneously provide eco-friendly and long-term cost-friendly solutions. This contribution provides an overview of the design of geothermal piles based on geometry variations. Hence, thermo-mechanical analyses are performed for axially loaded piles based on the load transfer approach using t-z curves method. With an absence of precise regulations and standards, the aim of these analyses is to simplify the design of thermo-active piles by generating an envelope chart utilizing the results for piles with different lengths and diameters. However, keeping a more realistic ratio of the geometry is of a significant importance, so that the piles are applicable on real project solutions.

 

How to cite: Smiljanovska, M., Mroueh, H., Habert, J., and Josifovski, J.: Elaboration of charts based on geometry variations for the design of thermo-active piles, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-584, https://doi.org/10.5194/egusphere-egu2020-584, 2020.

EGU2020-15060 | Displays | ERE2.8

Development and testing of an innovative energy wall system in Torino (Italy)

Matteo Baralis and Marco Barla

Shallow geothermal energy (SGE) is increasingly being regarded as a valuable solution for space heating and conditioning because of high efficiency, diffuse availability and low environmental impact. Significant growth in the number of installations is envisaged as a result of energy policies and European Directives. Indeed, the obligations in the construction sector about the share of energy supply from renewable sources is increasingly pushing the design of new and renovated buildings. On the one hand shallow geothermal energy is suitable as a sustainable and distributed energy source. On the other hand, significant installation costs related to drilling of traditional installations represent an hampering factor. Thermally activating geostructures such as piles, diaphragm wall, tunnels and anchors can allow to include these costs in the construction of the structural elements. Moreover, a large availability of operational surface is represented by new and/or existing building heritage in urban areas as most of them  have underground levels that can be equipped with heat exchangers.

This contribution introduces a novel modular very shallow geothermal exchanger as part of a Heating, Ventilation and Air Conditioning (HVAC) system. The system concept allows its application not only to new structures and buildings but also to existing ones. While the low depths interested may penalize the heat exchange rates, on the contrary, extremely low installation costs make the cost-benefit ratio of this new technology extremely interesting and promising.

A first prototype consisting of three modules was designed by the authors and installed in an office building in Torino (Italy). External deployment of pipes to the basement wall in two different arrangements was realized in order to test system efficiency. Due to the experimental nature of the tests, a large number of sensors were placed to monitor the additional stresses and strains on the wall and the thermal regime of the partially saturated ground volume involved in heat exchange.

Preliminary thermal performance tests were performed together with numerical modelling re-interpretation. On the basis of the first tests and interpretation carried out, it was demonstrated that remarkable heat exchange rates of up to 20 and 27 W/m2 could be injected/extracted from the ground in summer and winter respectively. Furthermore, the monitoring records suggest that extremely low affection of ground thermal status is operated by the system with respect to analogous non thermo-active walls. This evidence is extremely promising in the perspective of wide and dense diffusion of this new shallow geothermal energy system in urban areas where thermal interferences should be limited or avoided.

How to cite: Baralis, M. and Barla, M.: Development and testing of an innovative energy wall system in Torino (Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15060, https://doi.org/10.5194/egusphere-egu2020-15060, 2020.

EGU2020-4626 | Displays | ERE2.8

A case study of 5th generation district heating and cooling based on foundation pile heat exchangers (Vejle, Denmark)

Søren Erbs Poulsen, Maria Alberdi-Pagola, Karl Woldum Tordrup, Davide Cerra, and Theis Raaschou Andersen

We present the findings of a recently concluded research project, investigating the possibilities for collective heating and cooling supply of a planned, relatively small residential area (Rosborg Ø) in Ny Rosborg, Vejle, Denmark with ground source heat pumps utilising foundation pile heat exchangers (a.k.a. energy piles, EP). Individual EP foundations connect to a distribution network of uninsulated geothermal pipes, buried at shallow depth (cold district heating, CDH) from which connected consumers can supply heating with heat pumps as well as passive or active cooling.

To this end, the project has developed a geothermal screening procedure based on a combined analysis of geophysical data, borehole information, pile testing and laboratory measurements of soil thermal properties. A prototype computational temperature model of CDH networks has been developed for estimating the performance of EP based heating and cooling supply of Rosborg Ø. Finally, the project has developed a complete business (case) model for EP based CDH with a well-defined cost structure in which total fixed and variable costs can be quantified in specific projects.

The mapping of the geothermal potential demonstrates that CDH most likely can fully supply the estimated energy demand of the planned buildings in Rosborg Ø. However, recalculation of the scenario is necessary once additional information on the planned buildings become available. This conclusion is further supported by operational data from the EP foundation at the nearby Rosborg Gymnasium, demonstrating excess heating and cooling possibilities (beyond the demand of the building itself). Further analyses of the data from the Gymnasium estimates the average energy efficiency ratio to 24.8 for the passive cooling during July and early August 2018, roughly ten times higher than that of traditional Air Conditioning (AC). Moreover, the Gymnasium is able to supply its cooling needs passively 97% of the time where cooling is required, implying that the variable cost of cooling with EPs is exceptionally low.

The initial investment required for EP based CDH is higher, however, the variable costs of heating and cooling are greatly reduced relative to those of traditional District Heating (DH) and AC. Consequently, the estimated payback period for collective EP based CDH supply of Rosborg Ø is ca. 4.5 years. The relatively short payback period is due to a drastic reduction (of 80%) of the combined variable costs of heating and cooling with EPs, relative to traditional DH and AC. The contributing factors to the short payback period are the relatively low costs of electricity, the high COP of the heat pump, a relatively high, annual fixed tariff imposed by traditional DH and finally the exceptionally low costs of passive cooling/seasonal heat storage. As such, the project demonstrates a truly renewable, economically competitive heat pump technology to supply collective building heating and cooling/seasonal heat storage for the future energy supply in Denmark.

How to cite: Poulsen, S. E., Alberdi-Pagola, M., Tordrup, K. W., Cerra, D., and Andersen, T. R.: A case study of 5th generation district heating and cooling based on foundation pile heat exchangers (Vejle, Denmark), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4626, https://doi.org/10.5194/egusphere-egu2020-4626, 2020.

EGU2020-20952 | Displays | ERE2.8

Experimental and numerical performance assessment of standing column well operating strategies

Gabrielle Beaudry, Philippe Pasquier, Denis Marcotte, and Alain Nguyen

Standing column wells (SCWs) are efficient ground heat exchangers that use local groundwater as a heat source/sink for heating and cooling buildings. In a SCW, high heat exchange rates are achieved by recirculating groundwater in a single deep (75 m to 450 m) and uncased borehole. Discharging (“bleeding”) a small amount of the pumped water outside the SCW also allows maintaining the groundwater temperature within the heat pump’s operational range during peak demand periods. This strategy has been identified as the most significant parameter of SCW operation and is associated with reductions in total length, surface and cost of the borehole heat exchanger compared with the more common closed-loop systems.

This work aims at improving knowledge of the dynamic mass and heat transfer processes involved in SCW operation, in order to promote adoption of this energy-efficient technology and encourage good practice. To this end, data is collected using an experimental SCW system located near the city of Montreal, Canada, and made of a 215-m-deep SCW and a 150-m-deep injection well available for discharge of bleed water. The wells are also connected to a large-scale geothermal laboratory designed and equipped to mimic the heating and cooling operation of a small commercial building. First, an advanced finite-element model coupling advection-diffusion of heat and groundwater flow within a SCW and the surrounding ground is developed in the Comsol Multiphysics environment and is validated using experimental datasets collected through downhole temperature measurements, a pumping test, a thermal response test as well as 25 days of winter operation. The numerical model is then used to evaluate the impact of the pumping arrangement and bedrock fracturation on the well’s outlet temperature. Secondly, the operational parameters logged during the dynamic heat extraction test are analysed to provide insight about various operating strategies and their effect on the system’s performance.

The work conducted so far demonstrates that the proposed finite-element model reproduces the hydraulic and thermal behaviours of a SCW with satisfying accuracy. Numerical results suggest that placing the submersible pump near the top of the well avoids installation and maintenance difficulties without compromising heat pump operation compared with the usual reverse configuration. It is also shown that deep fractured zones are beneficial to heat pump operation in heating mode, whereas near-surface fracturing tends to impair the performance of the system throughout winter as it eventually favours recharge of the well with colder water. At last, analysis of the winter test data indicates the effectiveness of a three-level bleed control and on-off sequence for maintaining the groundwater temperature above the freezing point, while minimizing the volume of discharged water and allowing to reach a 160 W/m heat extraction rate.

How to cite: Beaudry, G., Pasquier, P., Marcotte, D., and Nguyen, A.: Experimental and numerical performance assessment of standing column well operating strategies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20952, https://doi.org/10.5194/egusphere-egu2020-20952, 2020.

EGU2020-20710 | Displays | ERE2.8

Interactions between energy geostructures in the same aquifer

Thibault Badinier, Jean de Sauvage, Fabien Szymkiewicz, and Bruno Regnicoli Benitez

Energy geostructures are a very cost-effective geothermal solution to produce renewable energy for the heating and cooling needs of the buildings. Their principle is to attach heat exchange pipes to the reinforcing cages of geotechnical structures (foundations, retaining walls, …). Mechanical and thermal roles are assigned to the same structures in order to reduce the economic and ecological costs.

Perturbations of the temperature field induced in the soil by this technology are propagated through conduction, diffusion and advection along the water-flow, leading to thermo-hydro-mechanical interactions between neighbouring structures. The behaviour of downstream energy geostructures is affected by the presence of upstream ones. In order to achieve a smart management of the shallow geothermal development at the city scale, it is crucial to characterize these interactions and their influence on the thermal efficiency.

For this purpose, a group of nine energy piles has been studied in Sense-City, a mini city where a specific climate can be imposed and the underground water-flow can be controlled. The piles can be thermally activated separately and are equipped with optic fibre to monitor their temperature evolution through time. Different groundwater conditions were imposed and different combinations of activated piles were studied.

To extrapolate and upscale the results, a numerical model was developed with CESAR-LCPC, a FEM software. Challenged by the experimental observations, the numerical model allowed simulating more complex boundary conditions and thermal infrastructure configurations. Furthermore, numerical modelling are able to simulate a long term experiment and to predict potential multi-year thermal shift.

Using combination of experimental and numerical experiments, observations can be made on the positive or negative consequence of energy geostructures interactions.

How to cite: Badinier, T., de Sauvage, J., Szymkiewicz, F., and Regnicoli Benitez, B.: Interactions between energy geostructures in the same aquifer, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20710, https://doi.org/10.5194/egusphere-egu2020-20710, 2020.

EGU2020-22207 | Displays | ERE2.8

A calibrated 3D thermal model of urban heat fluxes into the shallow subsurface

Monika Kreitmair, Asal Bidarmaghz, Ricky Terrington, Gareth Farr, and Ruchi Choudhary

The growth of urban populations, combined with the limited availability of above-ground space, is resulting in the increased use of underground structures as living spaces, e.g. residential basements. Such subsurface structures constitute continuous sources and sinks of heat to and from the surrounding underground environment, particularly if maintained at comfortable temperatures. In heavily populated cities and city-centres, underground temperature increases due anthropogenic heat fluxes are well-established, known as the urban underground heat island effect. Due to limited availability of long-term underground temperature data, models looking at subsurface temperature changes caused by man-made structures are difficult to calibrate. However, accurately accounting for the underground thermal climate is essential in ensuring efficient heating and cooling of underground structures as well as correctly estimating the geothermal potential in areas affected by the heat fluxes. The work to be presented explores the impact of temperature-maintained subsurface structures on the thermal climate of the shallow subsurface by developing a 3D finite element model of the Cardiff (UK) city-centre, using COMSOL Multiphysics. The model takes into account conductive and convective heat transfer between the ground and basements as well as geological features and existing hydraulic head measurements. Calibration of the model is performed using time-series temperature data, collected over several years by monitoring boreholes distributed throughout the modelled domain, provided by the British Geological Survey. This constitutes an important step towards accurately characterising the effects of underground urban heat islands and better understanding the human impact on the below ground thermal climate.

How to cite: Kreitmair, M., Bidarmaghz, A., Terrington, R., Farr, G., and Choudhary, R.: A calibrated 3D thermal model of urban heat fluxes into the shallow subsurface, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22207, https://doi.org/10.5194/egusphere-egu2020-22207, 2020.

EGU2020-21015 | Displays | ERE2.8

Assessing grouting mix thermo-physical properties for shallow geothermal systems

Enrico Garbin, Ludovico Mascarin, Eloisa Di Sipio, Gilberto Artioli, Javier Urchueguía, Dimitris Mendrinos, David Bertermann, Jacques Vercruysse, Riccardo Pasquali, Adriana Bernardi, and Antonio Galgaro

The main goal of the EU funded GEO4CIVHIC project is the development of more efficient and low-cost geothermal systems for conditioning retrofitting civil and historical buildings. In this framework, the identification of the most appropriate grout for different heat exchangers is a key factor for improving the overall efficiency of shallow geothermal systems. Therefore, a dedicated investigation was focused on the selection and optimization of the thermo-physical properties of grouting products to be used for:

  • the sealing of the coaxial geothermal probes’ head characterized by different installation depths
  • the sealing of the coaxial geothermal heat exchangers by filling the annular gap between the outer casing and the geological formations exposed to the wellbore

 

In both cases, the thermo-physical behavior of conventional and thermal enhanced grouts has been determined in laboratory for the purpose of manufacturing satisfactory cement based grouts with a real in-situ application. On the one hand, it is important to identify the grout mixtures having a suitable in situ workability, that is those satisfying specific conditions in terms of injection pressure, grout flowability, open working time and costs. On the other, it is essential to determine those providing optimal heat transfer between the probe and the surrounding ground.

Several lab experiments were performed on commercially available and enhanced selected mixtures to define (i) the workability and the flowability of the grouts; (ii) fundamental properties like mechanical strength, thermal conductivity and permeability of the hardened materials; (iii) leakage and calorimetric behavior, useful to identify sealing properties and grout setting times; (iv) viscosity and (v) density of the cement based mixture able to give information about the grout rate of descent and thus its pumpability under pressure.

Lastly, according to the lab results, few grout mixtures were selected as the best choice to be applied in situ for sealing the head of the geothermal probes’ and the annular space between the outer casing and the geological formations exposed to the wellbore. Therefore, this work attempts to address a knowledge gap of the thermo-physical properties, behavior and characterization of grouts for borehole heat exchangers (BHE), that are little studied and known.

 

How to cite: Garbin, E., Mascarin, L., Di Sipio, E., Artioli, G., Urchueguía, J., Mendrinos, D., Bertermann, D., Vercruysse, J., Pasquali, R., Bernardi, A., and Galgaro, A.: Assessing grouting mix thermo-physical properties for shallow geothermal systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21015, https://doi.org/10.5194/egusphere-egu2020-21015, 2020.

EGU2020-21275 | Displays | ERE2.8

Determination of thermal conductivities in the laboratory and the field: A comparison

Linda Schindler, Sascha Wilke, Simon Schüppler, Christina Fliegauf, Hanne Karrer, Roman Zorn, Hagen Steger, and Philipp Blum

The thermal conductivity of the subsurface is a fundamental parameter for the design of borehole heat exchangers in shallow geothermal energy systems. An average thermal conductivity value is usually assumed. Under real conditions, however, the thermal conductivity at depth can vary considerably depending on the local petrophysical and mineralogical properties of the subsurface (e.g. porosity). Hence, the aim of this study was to compare these properties of the subsurface with the thermal conductivities measured in the laboratory and in the field and to highlight possible correlations. For this purpose, a test field was established in the northern Black Forest (Germany) by obtaining an undisturbed drilling core of about 100 m length from sandstone of the Middle to Upper Buntsandstein formation and then installing a borehole heat exchanger (BHE). Various rock parameters were determined in the laboratory on 160 selected samples of the drilling core. Among other parameters, thermal conductivities under saturated and unsaturated conditions were measured and compared with values determined by depth-resolved classical and enhanced thermal response tests in the borehole heat exchanger (TRT). Furthermore, the porosity, permeability, grain density and pore diameter as well as mineralogical composition of the sandstone were intensively studied in the laboratory. The results do not show clear correlations between thermal conductivity, permeability and density. In contrast to those reported in literature, our results indicate a moderate correlation between porosity and thermal conductivity and a more pronounced dependence on grain size.

With regard to the depth profile of the thermal conductivity, the results between laboratory and field measurements were mainly consistent. The highest thermal conductivities (4.3 W/mK in the laboratory and 4.5 W/mK in the field) confirm the suitability of the Upper and Middle Buntsandstein formation for shallow geothermal installations. Most of these rocks represent typical fluvial deposits, so that the results obtained can be easily transferred to other regions with similar sandstone deposits.

How to cite: Schindler, L., Wilke, S., Schüppler, S., Fliegauf, C., Karrer, H., Zorn, R., Steger, H., and Blum, P.: Determination of thermal conductivities in the laboratory and the field: A comparison, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21275, https://doi.org/10.5194/egusphere-egu2020-21275, 2020.

EGU2020-19146 | Displays | ERE2.8

Concept for shallow geothermal opportunity mapping

David Boon, Gareth Farr, Laura Williams, Stephen Thorpe, Ashley Patton, Rhian Kendall, Alan Holden, Johanna Scheidegger, Suzanne Self, Corinna Abesser, and Gareth Harcombe

Reaching Net Zero CO2 emissions by 2050 will require rapid and wide-scale deployment of renewable heating technologies in rural and urban areas, including open and closed loop type production wells and borehole heat exchangers, supplying individual, shared, and centralised heat pumps as part of wider district heating and cooling grids.  Ground and groundwater conditions are naturally variable and are a key factor in system viability, capital cost and long-term performance.  Engineering approaches for heating and cooling of buildings should be optimised for the local thermo-geological conditions to avoid system interference and thermal degradation.  Sustainable use of shallow geothermal systems can be achieved by adopting an environmental stewardship approach, integrating geological information within energy master plans, taking full advantage of subsurface data visualisation technology and integrated planning and modelling tools.

We present a method for creating a digital shallow geothermal opportunities map - mostly aimed at moderate- to expert-skill level geoenvironmetal and energy consultants, planners and civil engineers.  The output is a digital 1:50 000 scale equivalent thematic map, that provides a synthesis of available technical information by combining data such as 3D superficial geological model data - delimiting aquifer and non-aquifer boundaries, groundwater levels and temperatures, aquifer thickness, flow direction, possibly with inset tables summarising groundwater chemistry and key physical properties of the main geological units such typical thermal conductivity.  Built infrastructure that could constrain drilling locations, as well as potential water discharge points and open water heat source and storage opportunities, such as sewers, rivers, canals, docks, and lakes, might also be included in the map.  Local development plans and heat demand mapping data could then be integrated with the opportunities map to identify and prioritise districts that would benefit from more detailed viability studies for conversion of fossil fuel heating systems to low carbon heating and cooling technologies.

This project has received funding from the European Union’s H2020 research and innovation programme under the GeoERA MUSE project – Managing Urban Shallow Geothermal Energy.

How to cite: Boon, D., Farr, G., Williams, L., Thorpe, S., Patton, A., Kendall, R., Holden, A., Scheidegger, J., Self, S., Abesser, C., and Harcombe, G.: Concept for shallow geothermal opportunity mapping, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19146, https://doi.org/10.5194/egusphere-egu2020-19146, 2020.

The State of Geneva in Switzerland is determined to increase the share of renewable energy in its heating mix to reduce its dependence from fossil fuels and their greenhouse gas emissions. Geothermal energy from shallow and medium depths is identified as one of the new renewable energy sources to meet the high heat demand in urban areas of Geneva in combination with the district heating network. The program GEothermie 2020, led by the local utility Services industriels de Genève (SIG) and the State of Geneva, aims to understand the characteristics of the State’s subsurface to allow for sustainable use of geothermal energy, while considering the technology's environmental impacts.

In this study, the environmental impacts of different geothermal heating systems for groundwater extraction in the State of Geneva were quantified using Life-Cycle Assessment (LCA). A systematic literature review revealed that most studies of geothermal LCA until now focused either on shallow geothermal applications with heat pumps or on high-enthalpy systems for electricity production. There was a lack of LCA studies for geothermal systems involving groundwater extraction from shallow and medium depth, even if the number of these systems is growing internationally.

In the first phase of our LCA study, we built six scenarios, integrating the geothermal subsurface characteristics and the district heating designs at the surface. We built a model to simulate material and energy flows and create life-cycle inventories. Critical parameters such as temperature, flowrate, well depths, and the seasonal heating demand of residential buildings were used as the input parameters. For each scenario, we defined upper and lower limits for geothermal production and material intensity, and a reference case representative of an existing or ongoing project in Geneva.

In the second phase, we quantified the ranges of environmental impacts of the scenarios using the Ecoinvent 3.6 database and ReCiPe 2016 Midpoint characterization factors.  We performed hotspot analysis to understand the contribution of life-cycle steps to selected environment impacts. Subsequently, we introduced other heat sources such as electric heating, waste incineration with district heating, and gas boilers into the reference cases, and analyzed their impacts. We compared these impacts with those of other heat systems such as oil boilers, ground source heat pumps, waste incineration, and centralized gas boilers.

We found that all of our scenarios of shallow-to-medium geothermal heating systems were less detrimental to the environment than oil boilers and centralized gas boilers in terms of global warming, air pollution, fossil resource scarcity, and acidification impacts. The ground source heat pumps were less detrimental than our geothermal scenarios in most cases, except for acidification. The hotspot analysis identified the operation phase as the activity that contributed the most to the environmental impacts in most cases, followed by the activities for the subsurface development or heating system construction. The latter became increasingly dominant when the heat production output was higher. Lastly, we found that introducing centralized gas boilers and waste heat into the district heating system increased these impacts, whereas the opposite was true when the low-carbon Swiss electric heating was introduced instead.

How to cite: Pratiwi, A. S., Jaxa-Rozen, M., and Trutnevyte, E.: How will geothermal energy transform the environmental performance of the heating mix of the State of Geneva from a life-cycle perspective?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10980, https://doi.org/10.5194/egusphere-egu2020-10980, 2020.

The design by optimization of hybrid ground-coupled heat pump (Hy-GCHP) systems is a complex process that involves dozens of parameters, some of which cannot be known with absolute certainty. Therefore, designers face the possibility of under or oversizing Hy-GCHP systems as a result of those uncertainties. Of course, both situations are undesirable, either raising upfront costs or operating costs. The most common way designers try to evaluate their impacts and prepare the designs against unforeseen conditions is to use sensitivity analyses, an operation that can only be done after the sizing.

Traditional stochastic methods, like Markov chain Monte Carlo, can handle uncertainties during the sizing, but come at a high computational price paid for in millions of simulations. Considering that individual simulation of Hy-GCHP system operation during 10 or 20 years can range between seconds and minutes, millions of simulations are therefore not a realistic approach for design under uncertainty. Alternative stochastic design methodologies are exploited in other fields with great success that do not require nearly as many simulations. This is the case for the conditional-value-at-risk (CVaR) in the financial sector and for the net present value-at-risk (NPVaR) in civil engineering. Both financial indicators are used as objective functions in their respective fields to consider uncertainties. To do that, they involve distributions of uncertain parameters but only focus on the tail of distributions. This results in quicker optimizations but also in more conservative designs. This way, they remain profitable even when faced with extremely unfavorable conditions.

In this work, we adapt the NPVaR to make the sizing of Hy-GCHP systems under uncertainties viable. The mixed-integer non-linear optimization algorithm used jointly with the NPVaR, the Hy-GCHP simulation algorithm and the g-function assessment methods used are presented broadly, all of which are validated in this work or in referenced publications. The way in which the NPVaR is implemented is discussed, more specifically how computation time can be further reduced using a clever implementation without sacrificing its conservative property. The implications of using the NPVaR over a deterministic algorithm are investigated during a case study that revolves around the design of an Hy-GCHP system in the heating-dominated environment of Montreal (Canada). Our results show that over 1000 experiments, a design sized using the NPVaR has an average return on investment of 126,829 $ with a standard deviation of 18,499 $ while a design sized with a deterministic objective function yields 137,548 $ on average with a standard deviation of 33,150 $. Furthermore, the worst returns in both cases are respectively 35,229 $ and -32,151 $. This shows that, although slightly less profitable on average, the NPVaR is a better objective function when the concern is about avoiding losses rather than making a huge profit.

In that regard, since HVAC is usually considered a commodity rather than an investment, we believe that a more financially stable and predictable objective function is a welcome addition in the toolbox of engineers and professionals alike that deal with the design of expensive systems such as Hy-GCHP.

How to cite: Dusseault, B. and Pasquier, P.: A Net Present Value-at-Risk Objective Function for Uncertainty Mitigation in the Design of Hybrid Ground-Coupled Heat Pump Systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11511, https://doi.org/10.5194/egusphere-egu2020-11511, 2020.

EGU2020-7895 | Displays | ERE2.8 | Highlight

Utilizing the road bed for combined ground source heating and sustainable rainwater drainage in Hedensted, Denmark

Theis Raaschou Andersen, Karl Woldum Tordrup, and Søren Erbs Poulsen

We present a novel climate adaption technology – the Climate Road - that combines collective, ground source heat pump (GSHP) based heating with sustainable urban drainage of rain water (SUDS). The system utilizes the road bed simultaneously as a retarding basin for excess rain water and as the energy source for a GSHP. Surface water percolates through the permeable road paving and is retained in the gravel road bed during extreme precipitation events where the sewage system is often overloaded. Water is subsequently released once capacity is available again on the sewage network. In addition, geothermal piping is embedded in the roadbed, serving as the collector for individual GSHPs that supply connected households with heating. The primary benefit of the combined system is the saved digging costs and lost property value from establishing a separate rainwater basin and trench for the geothermal piping as the road bed is to be established under any circumstances. However, there is also a subtle yet positive effect on the performance of the GSHP, from constantly watering the geothermal piping.

We have constructed 50 m of Climate Road in Hedensted, Denmark. The road bed is 1 m deep and 8 m wide and can retain a maximum of 150 mm of precipitation, given that the catchment area is twice that of the road surface. Moreover, the road bed is hydraulically disconnected from the surrounding soil by means of bentonite mats, to prevent seepage of groundwater into the road bed. Water is discharged by drainage pipes to a nearby rainwater basin for experimental and practical purposes only. 800 m of geothermal piping is embedded in the road bed, supplying a nearby kindergarten with domestic hot water and room heating by means of a GSHP. The Climate Road is fully instrumented with temperature sensors in the road bed, flow meters to measure water discharge and energy metering on the GSHP. We present the performance of the Climate Road in terms of supplied heating and the coefficient of performance (COP) for the heat pump in addition to drained water volumes for the first year of operation.

How to cite: Andersen, T. R., Tordrup, K. W., and Poulsen, S. E.: Utilizing the road bed for combined ground source heating and sustainable rainwater drainage in Hedensted, Denmark , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7895, https://doi.org/10.5194/egusphere-egu2020-7895, 2020.

EGU2020-508 | Displays | ERE2.8 | Highlight

Shallow geothermal technology as alternative to diesel heating of subarctic off-grid autochthonous communities in Northern Quebec (Canada)

Nicolò Giordano, Evelyn Gunawan, Félix-Antoine Comeau, Mafalda Miranda, Hubert Langevin, Matteo Covelli, Paul Piché, Jessica Chicco, Stéphane Gibout, Didier Haillot, Alessandro Casasso, Giuseppe Mandrone, Cesare Comina, Richard Fortier, and Jasmin Raymond

In the north of Québec (Canada), off-grid aboriginal communities rely on diesel for both space heating and electricity production. Renewable alternatives are therefore necessary to reduce the impact of burning diesel in a region with strong population growth and increasing energy needs. The main challenges are the subarctic environment (more than 8000 heating degree days), the presence of permafrost and the lack of local expertise on drilling and installation of borehole heat exchangers.

The communities of Kuujjuaq (58 °N) and Whapmagoostui-Kuujjuarapik (W-K, 55 °N) were chosen as case studies to evaluate the shallow geothermal potential and predict the long-term behaviour of ground source heat pumps (GSHP) and underground thermal energy storage systems (UTES). Local geology mainly consists of low permeable and thermally conductive crystalline bedrock (thermal conductivity of 2-4 W/mK) underlying highly permeable, frost-susceptible and poorly conductive marine sediments (thermal conductivity of 1-1.5 W/mK), generally not thicker than 30-40 m. Electrical resistivity tomography and ground penetrating radar surveys have been carried out to locally evaluate the presence of ice-rich ground that strongly depends on the local hydrogeological conditions. Average underground temperature in the first 100 m is around 1 °C in Kuujjuaq and 2 °C in W-K. Geothermal gradient and heat flux were estimated to be on average 15 °C/km and 40 mW/m2, respectively.

Results of the studies carried out in these villages show that both GSHP and UTES are viable technologies to replace part of the current diesel consumption of residential buildings and drinking water facilities, with 10% to 50% primary energy saving depending on the technology. Fifty years’ life-cycle cost analyses demonstrated that the levelized cost of energy for GSHP and UTES is as low as 0.10 and 0.19 USD$/kWh, respectively, compared to the business-as-usual scenario standing at 0.21 USD$/kWh. It also turned out that the energy and drilling costs are key obstacles to a widespread deployment of these technologies in the North. A cost of 110 USD$/m has been defined as a threshold for getting interesting paybacks on the initial financial investment. UTES is also a valuable technology aiming to extend the growing season of community greenhouses in place in both Kuujjuaq and W-K. In Kuujjuaq, a coupled daily and seasonal heat storage is under study to provide renewable heat and help increase the food security in Nunavik.

Future activities aim at the set-up of a first demonstration plant to be tested in a subarctic environment with underground close to permafrost conditions. A 200-m well will be drilled in 2020 in W-K and the installation of a borehole heat exchanger will be showcased for technological transfer. Conventional thermal response tests (TRT) and a novel approach of oscillatory TRT will also be carried out to evaluate the in-situ thermal conductivity and heat capacity.

How to cite: Giordano, N., Gunawan, E., Comeau, F.-A., Miranda, M., Langevin, H., Covelli, M., Piché, P., Chicco, J., Gibout, S., Haillot, D., Casasso, A., Mandrone, G., Comina, C., Fortier, R., and Raymond, J.: Shallow geothermal technology as alternative to diesel heating of subarctic off-grid autochthonous communities in Northern Quebec (Canada), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-508, https://doi.org/10.5194/egusphere-egu2020-508, 2020.

EGU2020-7032 | Displays | ERE2.8 | Highlight

The UK Geoenergy Observatory in Glasgow, Scotland: a New Facility for Mine Water Geothermal Research

Alison Monaghan, Vanessa Starcher, Hugh Barron, Corinna Abesser, Brighid O Dochartaigh, Fiona Fordyce, Oliver Kuras, Sean Burke, Helen Taylor-Curran, and Richard Luckett

EGU2020-3684 | Displays | ERE2.8

Using buildings' foundation as a GHE in moderate climates
not presented

Lazaros Aresti, Paul Christodoulides, and Georgios A. Florides

Shallow Geothermal Energy, a Renewable Energy Source, finds application through Ground Source Heat Pumps (GSHPs) for space heating/cooling via tubes directed into the ground. There are two main categories of Ground Heat Exchanger (GHE) types: the horizontal and the vertical types. Ground Heat Exchangers (GHEs) of various configurations, extract or reject heat into the ground. Even though GSHP have higher performance in comparison to the Air Source Heat Pumps (ASHPs), the systems high initial costs and long payback period have made it unattractive as an investment. GSHP systems can also be utilized in the buildings foundation in the form of Thermo-Active Structure (TAS) systems or Energy Geo-Structures (EGS), with applications such as energy piles, barrette piles, diaphragm walls, shallow foundations, retaining walls, embankments, and tunnel linings. Energy piles are reinforced concrete foundations with geothermal pipes, whereby the buildings foundations are utilized to provide space heating and cooling. Apart from energy piles, another EGS system can be achieved by the incorporation of the building’s foundation bed as a GHE. Foundation piles are not required in all constructions, but a building’s foundation bed is mandatory. This configuration is still based on the principles of the energy pile.

Energy piles have yet to be applied in Cyprus and, thus, a preliminary assessment considered and investigated before application would be useful. The potential of the GSHP systems by utilizing the building’s foundation through energy piles is considered here, for a moderate climate such as Cyprus, towards a Zero Energy Building. Typical foundation piles geometry in Cyprus consists of a 10m depth, a 0.4m diameter and reinforced concrete as a grout material, which is used at the foundation bed of the building. A typical dwelling in Cyprus is selected to be numerically modelled in this study. It is a three-bedroom, two-storey house with a 190m2 total floor area, matching the thermal characteristics of a Zero Energy Building (i.e., U-values of 0.4W/m2/K on all walls and ceiling and 2.25 W/m2/K on all doors and windows, respectively). A full-scale model is developed in COMSOL Multiphysics software, to examine the energy rejected or absorbed into the ground by taking the heating and cooling loads of the typical dwelling in Cyprus. The convection-diffusion equation for heat transfer is used with the three-dimensional conservation of heat transfer for an incompressible fluid on all domains except the pipes, where a simplified equation is used. Different months in winter and summer are accounted for the simulations and the fluid-in – fluid-out temperature difference is presented. Finally, an economic evaluation of the systems examined above is presented, in order to check its viability. It is concluded that utilizing the dwelling’s foundations can be a better investment than using GHEs in boreholes.

How to cite: Aresti, L., Christodoulides, P., and Florides, G. A.: Using buildings' foundation as a GHE in moderate climates, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3684, https://doi.org/10.5194/egusphere-egu2020-3684, 2020.

The use of foundation structures (piles) coupled to a heat pump system, commonly referred to as geothermal energy pile (GEP) system, provides a renewable energy solution of achieving space heating and cooling in buildings; whilst also being utilised for the structural stability of the overlying structures. The system operates by exchanging the low-grade heat energy within the shallow earth surface with the building, via the circulation of heat carrier fluid enclosed in a high-density polyethylene plastic pipes. In summer, heat energy is extracted from the building and transferred into the ground to achieve space cooling. While in winter, the ground heat energy is harnessed and transferred to the building to achieve sustainable space heating. This paper investigates the thermal performance of the GEP system under the effects of factors such as initial soil pore water content and ground water flow.

The study utilises coupled thermo-hydraulic finite element modelling and analyses to achieve the aim of this study. It was observed that the initial pore water volume and groundwater flow are very significant factors that determine the amount of heat energy that can be harnessed using the system.

 

How to cite: Sani, A. K. and Singh, R. M.: Numerical investigation of the performance of geothermal energy piles under different soil moisture conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20003, https://doi.org/10.5194/egusphere-egu2020-20003, 2020.

EGU2020-11711 | Displays | ERE2.8

Observations from shallow geothermal modelling case studies in Canada and the UK

Corinna Abesser, Robert Schincariol, Jasmin Raymond, Alejandro Garcia Gil, Jonathan Busby, Ronan Drysdale, Al Piatek, Nicolo Giordano, Nehed Jaziri, and John Molson

Global demands for energy efficient heating and cooling systems coupled with rising commitments toward net zero emissions building infrastructure have resulted in wide deployment of shallow geothermal systems and in the continued growth in the global geothermal heat pump (GHP) market. With increasing deployment of these systems in urban areas, there is growing potential and risk for these systems to impact the subsurface thermal regime and to interact with each other or with nearby heat-sensitive subsurface infrastructures.

GHP systems have been studied in urban environments with respect to their effects on the subsurface thermal regime, and various modelling studies have investigated the sensitivity of their performance to key (hydro)geological and operational parameters. The focus of these studies has been on isolated systems, where flow conditions and background subsurface temperatures are assumed to be constant, impacted only by the modelled system itself during its operation. However, less attention has been paid to the effects on GHPs functional efficiency from perturbations in the wider hydrogeological and thermal regime, e.g. due to urbanization, multiple BHEs within tight (residential) clusters or competing subsurface uses requiring pumping of groundwater.

In this paper, we present three numerical modelling case studies, from the UK and Canada, which examine GHP systems response to perturbation of the wider hydrogeological and thermal regime. We investigate the influence of key parameters and different model realisations, e.g. relating to system design, unbalanced thermal ground loads and environmental conditions, on the modelled GHP system efficiencies and thermal interference. We highlight findings that are relevant from an economic point of view but also for regulations. Findings are discussed within the context of the contrasting design and operational pattern typical for the UK / Europe and Canada/ North America.

How to cite: Abesser, C., Schincariol, R., Raymond, J., Garcia Gil, A., Busby, J., Drysdale, R., Piatek, A., Giordano, N., Jaziri, N., and Molson, J.: Observations from shallow geothermal modelling case studies in Canada and the UK , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11711, https://doi.org/10.5194/egusphere-egu2020-11711, 2020.

EGU2020-21366 | Displays | ERE2.8

Numerical modelling of energy geo-structures for building retrofitting

Diana Salciarini and Francesco Cecinato

Energy piles (EPs), consisting in piled foundations equipped with heat exchangers, have been extensively studied in recent years, both from the thermo-mechanical response and energy performance points of view. However, most research refers to typical rotary bored, CFA or precast driven, medium diameter piles. Little attention has been devoted to so-called energy micropiles (EMPs), representing an opportunity to provide at the same time energy and structural retrofitting to existing buildings. Existing studies show that EMPs overall may thermally perform differently to EPs, but they are comparable in terms of specific heat flux.

In this work, a 3D FE numerical model is employed to perform a comprehensive parametric study considering design factors that are peculiar to EMPs, to assess the most important parameters to maximise their energy performance. The parameter space is efficiently explored resorting to a statistically-based Taguchi approach. Then, the model is employed to compare the overall energy performance of realistic EP and EMP foundation solutions, under the same building and underground conditions. Finally, practical guidance is provided about the optimal choice of design factors to achieve the best thermal performance whenever EMPs  are to be used based on geotechnical/structural design.

 

Acknowledgement: The second author wishes to acknowledge support from the EU’s Horizon 2020 Research and Innovation programme under Grant Agreement No 810980 - ENeRAG.

How to cite: Salciarini, D. and Cecinato, F.: Numerical modelling of energy geo-structures for building retrofitting, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21366, https://doi.org/10.5194/egusphere-egu2020-21366, 2020.

EGU2020-1953 | Displays | ERE2.8

Uncertainty Quantification of Borehole Thermal Energy Storage Facilities

Philipp Steinbach, Jens Lang, Daniel Otto Schulte, and Ingo Sass

Borehole thermal energy storages (BTES) have become a common implement for extracting and/or storing heat energy from and into the soil. Building these facilities is expensive, especially the drilling of boreholes, into which borehole heat exchangers are inserted. To cut costs, drilling methods, which can produce inaccuracies of varying degree, are utilized. This brings into question how much these inaccuracies could potentially affect the energy storage/extraction performance of a planned facility. To this end, we performed an uncertainty quantification for seasonally operated BTES facilities, where we studied the influence of geometries deviating from the planned layout and other sources of uncertainty, such as varying soil and material parameters.
In our research, we make use of a 3D simulation model for BTES facilities in a patch of soil with optional groundwater flow, designed as a system of partial differential equations (PDEs). The system is solved with a simulation toolkit, which was programmed as an extension for the finite element method solver KARDOS. The toolkit builds on previous work for the simulation tool BASIMO and was validated with benchmarks calculated with the commercial software FEFLOW, which specializes in heat transfer in porous media among other things. For the uncertainty quantification, we utilize an adaptive, anisotropic stochastic collocation method, which uses solutions of the PDE system as samples. We present the method and apply it to an illustrative as well as a practical example. Lastly, we discuss the results and assess the impact of deviating borehole paths on the performance of BTES facilities.

How to cite: Steinbach, P., Lang, J., Schulte, D. O., and Sass, I.: Uncertainty Quantification of Borehole Thermal Energy Storage Facilities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1953, https://doi.org/10.5194/egusphere-egu2020-1953, 2020.

EGU2020-19412 | Displays | ERE2.8

Harvesting Energy from Buried Infrastructure: current UKCRIC research

Fleur Loveridge, Paul Shepley, Ross Stirling, and Anil Yildiz

The UK Government has a commitment to reach net-zero emissions by 2050. Because 70% of heating comes from direct burning of natural gas, this target cannot be achieved without decarbonising the gas network. One of the best routes to decarbonise heating is through use of ground thermal energy storage coupled with ground source heat pump systems. However, heat pump systems retain high investments costs, mainly due to the expense of drilling dedicated ground heat exchangers (GHE) such as deep boreholes. One route to reducing these costs is to use buried infrastructure for simultaneous structural function and ground heat exchange. In the past deep foundations, embedded retaining walls and trial tunnels have all been used as GHE.  However, there is increasing interest in extending this approach to other shallow buried infrastructure, such as waste and drinking water distribution networks, and green infrastructure such as sustainable urban drainage and swales. 

The UK Collabatorium for Research in Infrastructure and Cities (UKCRIC) is a consortium founded by thirteen universities to provide an integrated research capability with a mission to underpin the renewal, sustainment and improvement of infrastructure and cities in the UK and elsewhere. Under the auspices of UKCRIC, a pump priming project called PLEXUS has been carried out. One of the research challenges of PLEXUS has been to consider how much heating and cooling capacity can be obtained from using civil engineering infrastructure as GHE, and whether there are any risks to original structural function from the GHE operation.  The project has included trial experiments for (i) soil element thermo-mechanical and thermo-hydraulic behaviour, (ii) the operation of sustainable urban drainage under heat injection, (iii) heat transfer characteristics of a near full scale water pipe segment, (iv) effects of temperature change on the formation of fats, oils and greases in waste water treatment systems. This paper will present a summary of key findings from the project and identify challenges for implementation of this valuable thermal resource. 

How to cite: Loveridge, F., Shepley, P., Stirling, R., and Yildiz, A.: Harvesting Energy from Buried Infrastructure: current UKCRIC research, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19412, https://doi.org/10.5194/egusphere-egu2020-19412, 2020.

The study shows the result of a detailed analysis aimed at verifying possible application of the technology related to the exploitation of low temperature geothermal resources for direct uses, with particular reference to the heating and cooling of public and private buildings in Rome, in order to enhance and improve its building stock.

The analysis started with collection and consultation of geological, stratigraphic, hydrogeological and thermal data available from bibliography and previous studies of the area. This represented a fundamental and useful step to determine a potentially suitable sector, both for geological and thermic characteristics of the lithologies recognized in the area. Pietralata, north east of Rome, was selected as "pilot site" out of 15 areas identified on the basis of the collected information. Within this pilot site, a High School - Technical Institute was recognized a suitable public building for the test.

The entire school complex has been discretized into three blocks. The analysis was made preliminarily for block 1, which is the largest, by calculating the heating energy requirements based on the climatic zone and the structural parameters of the building using the CARAPACE software (CAlcolo Resistivo Annuale Prestazioni Assetti Climatizzazione Efficienti), developed by SSE Department of RSE.

Starting from these needs, the analysis was carried out by hypothesizing and sizing a field of closed loop probes capable to meet 30% of the total energy needs expected for the building. Results thus highlighted, were a conclusion drawn by 16 probes with an average depth of 95 m each.

The analysis and the determinations made on the bibliographic basis were then validated with the experimental data derived from a geognostic survey by drilling up to a depth of 100 m from the surface, and conditioned for a Geothermal Response Test to determine the experimental value of the thermal capacity W/(m*K) of the lithologies.

From the aforementioned, the possibility to optimize the thermal conductivity profile of the ground was derived, in respect to the λ values corresponding to the stratigraphy derived from the survey.

The results, thus arrived, confirm the worth of the preliminary estimates and demonstrate how a field of 12 probes with a depth of 100 m each is enough to satisfy 30% of the energy needs of the users considered.

It must be also the focal point that Pietralata area is not the optimum in terms of thermal conductivity of the ground and lithologies, wherein the value of lambda was found to be around 1.6 W/(m*K). Nevertheless, the results established the correctness of the preliminary hypothesis in the applicability of the geothermal technology for the heating and cooling of existing buildings in the city of Rome.

The study was an experimental activity carried out with Roma Capitale Municipality – Infrastructure Department.

How to cite: Bernardo, N. and Moia, F.: Geological and numerical modelling of Thermal Ground Potential for building’s heating and cooling, using low temperature shallow geothermal: The “Pietralata Pilot Site” (Roma Capitale Area, Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2912, https://doi.org/10.5194/egusphere-egu2020-2912, 2020.

EGU2020-8584 | Displays | ERE2.8

European drillability mapping for shallow geothermal applications

Antonio Galgaro, Eloisa Di Sipio, Giorgia Dalla Santa, Adela Ramos Escudero, Jose Manuel Cuevas, Burkhard Sanner, Davide Righini, Riccardo Pasquali, Jacques Vercruysse, David Bertermann, Luc Pockele, and Adriana Bernardi

The overall goal of the EU funded project GEO4CIVHIC is the development of more efficient and low cost geothermal systems for conditioning retrofitting civil and historical buildings.

The assessment of the most suitable drilling technology for a given geological context could be very useful from both the technical and the economic point of view. In fact, the installation costs are one of the main economical barrier for a wider application of shallow geothermal systems, and they are mainly covered by the drilling time and costs (drilling machine and labour costs).

Generally, the drilling technology suitable on a given site and the related most proper ground heat exchanger are mainly dictated by the local stratigraphy (kind of materials/rocks, state of consolidation) and the local hydrogeological conditions, also affecting the drilling times and costs by requiring the application or not of the casing.

The ‘drillability’ concept has been defined as the prediction of the most suitable drilling technique related to a given underground for a certain borehole heat exchanger type, by taking into account the estimated drilling and installation time. Therefore, a ‘drillability’ map has been conceived at European scale in order to support the preliminary design phase of new ground source heat pump systems and to provide a first evaluation of the drilling costs and time for a given location. The map is based on the European geological map released by the European Geological Data Infrastructure (EGDI), freely available in the web, that complies with the INSPIRE (INfrastructure for Spatial InfoRmation in Europe) Directive. It is an ESRI Shape (vector file), Scale 1:1.500.000, Projection ETRS 1989 LCC. The EGDI map is connected to a list that collect all the geological context that can be found all around Europe; the list contains 203 different geological settings. The association among ‘drillability’ techniques and geological sequence was conducted by considering the knowledge of the partners that are expert in drilling operations in several European countries.

The classical drilling methods are here distinct into percussing, rotating, and combined percussion-rotation methods. The proposed map compares traditional drilling methods usually applied to install vertical ground heat exchangers as the rotary drilling with tricone or chevron bit and the traditional down-hole hammer (with or without casing) with the new drilling techniques developed within the EU funded project Cheap-GSHPs and GEO4CIVHIC.

So far a first ‘drillability’ map has been released with the drilling time and costs; further development will report the regulatory constraints related to drilling in specific areas.

The ‘drillability’ map at European scale is connected to a ‘drillability’ app still under development that will provide a first assessment of the most suitable drilling technique in a specific geological context both to direct users such as designers, drillers, administrators. Depending on the local geology identified by the users, the app will help to estimate the required drilling time and related costs, providing a preliminary information to start decision making and authorization processes.

Goo4Civhic Project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 792355.

How to cite: Galgaro, A., Di Sipio, E., Dalla Santa, G., Ramos Escudero, A., Cuevas, J. M., Sanner, B., Righini, D., Pasquali, R., Vercruysse, J., Bertermann, D., Pockele, L., and Bernardi, A.: European drillability mapping for shallow geothermal applications , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8584, https://doi.org/10.5194/egusphere-egu2020-8584, 2020.

EGU2020-18915 | Displays | ERE2.8

Assessing underground heat exchange and solar heat storage capabilities based on ground thermo-physical properties: the Euganean hills demo site (Italy)

Eloisa Di Sipio, Raffaele Sassi, Stefano Buggiarin, Silvia Ceccato, and Antonio Galgaro

The utilization and development of renewable energy sources (RES) is currently a topic of great interest in energy field. In detail, the coupling of different RES and related technologies, as solar thermal and shallow geothermal, for heating/cooling purpose of residential buildings is a promising sector. The possibility to store the thermal energy produced by solar panels in the underground during the summer season, when the insolation is greater, and to use the heat accumulated during the coldest periods, is strictly related, among others, both to the thermo-physical properties of rocks and to the solar radiation locally available. As the ground is the invariant component of the whole system, a better knowledge of its thermal properties (i.e. thermal conductivity, volumetric heat capacity…) is fundamental to evaluate the amount of heat that can be stored.

This paper presents an innovative methodological approach combining information related to underground thermal energy exchanging and storage capacity with the solar radiation, taking also into account the location of the possible end-users, that is the distribution of the residential buildings in the territory. The Euganean Hills area, located in the Po River Plain (north-east Italy), is selected as demonstration test site. A qualitative map, created using Geographycal Information System (GIS) application, has been realized in order to represent the “Ground thermal suitability” of a territory to sensible heat storage, that is the possibility to store solar energy in the underground for a later use.

This thematic map is a really promising tool, suitable for local administrator and professionals, for planning the possible exploitation of solar thermal renewable resources available in the area.

How to cite: Di Sipio, E., Sassi, R., Buggiarin, S., Ceccato, S., and Galgaro, A.: Assessing underground heat exchange and solar heat storage capabilities based on ground thermo-physical properties: the Euganean hills demo site (Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18915, https://doi.org/10.5194/egusphere-egu2020-18915, 2020.

EGU2020-5622 | Displays | ERE2.8

In situ investigation of the impact of cyclic thermal variations impact on the mechanical properties of sandy soil.

Sandrine Rosin-Paumier, Hossein Eslami, and Farimah Masrouri

The incorporation of heat exchangers into geostructures leads to changes in the temperature of the adjacent soil, which may affect its hydro-mechanical properties. In this study, mini-pressiometer tests were carried out in the vicinity of three experimental energy piles of 12 meters length and 0.52-meter diameter installed in saturated sandy soil. Tests were carried out in three locations and in two different depths (namely 3 and 4 meters in depth) before and after cyclic variations of their temperature. The pressuremeter parameters are the pressuremeter modulus EM, the limit pressure PL and the creep-pressure Pf. These parameters characterize the properties of the soils; some measurements were done close to the energy piles (1.25 meters from the center of the pile) using a mini-pressuremeter cell (380 mm in height and 28 mm in diameter). The comparison of the results before and after the four warming-cooling cycles (8° to 19° C) showed a thin thickening of the material at 3 meters depth. These results are coherent with in-lab measurements and with the results of the pile loading tests carried out later on the same site.

How to cite: Rosin-Paumier, S., Eslami, H., and Masrouri, F.: In situ investigation of the impact of cyclic thermal variations impact on the mechanical properties of sandy soil., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5622, https://doi.org/10.5194/egusphere-egu2020-5622, 2020.

EGU2020-19052 | Displays | ERE2.8

Online ground temperature and soil moisture monitoring of a shallow geothermal system with non-conventional components

Ludwin Duran, Darius Mottaghy, Ulf Herrmann, and Rolf Groß

We present first results from a newly developed monitoring station for a closed loop geothermal heat pump test installation at our campus, consisting of helix coils and plate heat exchangers, as well as an ice-store system. There are more than 40 temperature sensors and several soil moisture content sensors distributed around the system, allowing a detailed monitoring under different operating conditions.

In the view of the modern development of renewable energies along with the newly concepts known as Internet of Things and Industry 4.0 (high-tech strategy from the German government), we created a user-friendly web application, which will connect the things (sensors) with the open network (www). Besides other advantages, this allows a continuous remote monitoring of the data from the numerous sensors at an arbitrary sampling rate.

Based on the recorded data, we will also present first results from numerical simulations, taking into account all relevant heat transport processes.

The aim is to improve the understanding of these processes and their influence on the thermal behavior of shallow geothermal systems in the unsaturated zone. This will in turn facilitate the prediction of the performance of these systems and therefore yield an improvement in their dimensioning when designing a specific shallow geothermal installation.

How to cite: Duran, L., Mottaghy, D., Herrmann, U., and Groß, R.: Online ground temperature and soil moisture monitoring of a shallow geothermal system with non-conventional components, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19052, https://doi.org/10.5194/egusphere-egu2020-19052, 2020.

EGU2020-19601 | Displays | ERE2.8

The impact of Standing Column Well operation on Carbonate Scaling

Léo Cerclet, Benoît Courcelles, and Philippe Pasquier

Low-temperature geothermal systems have shown great potential to reduce greenhouse gas emissions. One emerging solution, named standing column well, is particularly promising and is characterized by low installation costs and higher thermal efficiency compared to widespread closed-loop wells. In a standing column well, groundwater is continuously recirculated in an uncased well. As the well and the mechanical devices are prone to clogging and scaling, the occurrence of new operational conditions can have an impact on long-term performance and generate significant maintenance costs. Although current literature identifies the main causes of clogging, the impact of the operation strategy of a standing column well operation on clogging development has not yet been extensively studied.

 

The chemical signature of groundwater and the operation parameters of a real-size experimental standing column well were monitored during a two-year period using a geothermal mobile laboratory. This laboratory contains heat pumps, heat exchangers, pumps, monitoring devices and a water treatment unit enabling treatment of a fraction of the total pumping flow. This work highlights how the operation of a standing column well impacts the clogging rate by establishing a direct link with the observed calcium concentrations. Two specific operation schemes were found to be critical for the development of clogging.

 

First, the “on-off” sequences of the pump allowed for water stagnation in the mechanical devices and promoted a temperature rise since the geothermal laboratory is maintained at 20oC, thus creating ideal conditions for precipitation. In addition, the calcium concentration in groundwater increased with shutdown duration and with a kinetic similar to the one observed in an independent batch test. This batch test conducted with demineralized water and samples of the local rock was carried out in close atmosphere at 10°C to measure the dissolution kinetics. Both the two-year monitoring and batch test confirm that groundwater slowly dissolves the carbonates in the standing column well that precipitate in the mechanical devices during the off sequences.

 

The second critical operation scheme was observed during cooling mode. As groundwater temperature gradually increases with the operation of the system, the calcium stability index increased, leading to precipitation in some mechanical devices. After two years of operation, some mineral deposits were recovered on the probes of two faulty flow sensors. The deposits were analyzed with a scanning electron microscope, which indicated high concentrations of calcium, oxygen, and carbon, all compatible with calcite precipitates. Further works will focus on the development of new operation strategies to hinder clogging and scaling of the mechanical equipment connected to a standing column well.

How to cite: Cerclet, L., Courcelles, B., and Pasquier, P.: The impact of Standing Column Well operation on Carbonate Scaling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19601, https://doi.org/10.5194/egusphere-egu2020-19601, 2020.

EGU2020-9184 | Displays | ERE2.8

Experimental risk assessment of carbonate scaling in the operation of high temperature – aquifer thermal energy storage (HT-ATES) systems

Hester E. Dijkstra, Cjestmir V. de Boer, Mariëlle Koenen, and Jasper Griffioen

High temperature - aquifer thermal energy storage (HT-ATES) is gaining momentum as sustainable option for the (seasonal) storage of heat, where geothermal heat may be one of the sources. To maximize the impact of geothermal systems, the heat produced in the summertime, which is not directly needed, can be temporarily stored in a groundwater aquifer for use in the winter. However, HT-ATES does not come without technical complications. One potential complication is carbonate scaling of the technical installation and/or the aquifer in the vicinity of the injection well. Precipitation of carbonates may occur when carbonate-saturated groundwater becomes heated, upon which the groundwater becomes increasingly supersaturated for carbonates. As part of the GEOTHERMICA project HEATSTORE, both a sampling method and an experimental set-up were developed. This experimental procedure enables the sampling and testing of groundwater from HT-ATES sites or else to determine the likelihood of calcium carbonate scaling in a HT-ATES system and, if so, identify the nature and extent.

For the HEATSTORE project, Groundwater was sampled at a HT-ATES test well drilled in Middenmeer, the Netherlands down to 370 meter depth. The sampling was done with a double walled vessel, which made it possible to maintain pressure on the water sample to prevent degassing of natural occurring dissolved gases like methane and carbon dioxide during sampling and storage, as well as preventing atmospheric contamination of the groundwater. The experiments were performed in two stainless steel autoclaves which were kept at 85 degrees Celsius for up to 5 days. Three types of experiments were performed to mimic the different components of the HT-ATES system: addition of a plate of stainless steel, addition of calcium carbonate crystals and addition of aquifer sediment. The first experiment did not show any carbonate precipitation, although geochemical modelling suggests oversaturation of calcite for the applied conditions. Calcite precipitation and recrystallization were observed only in the experiments with calcite crystal seeds added. The experiment with the aquifer sediment added to the reaction vessel, containing shell fractions and intact shells (e.g. Foraminifera), did not show calcite precipitation, neither showed the chemical analysis of the water at the end of the experiment a reduction in calcium concentration. Isotope analysis suggests that carbon dioxide was released by thermally enhanced degradation of sedimentary organic matter, which would have lowered the supersaturation of calcite.

These results suggest that aquifers, in which calcite is already present and limited (or no reactive) organic matter is available, could face a risk of scaling and subsequent injectivity/productivity issues when HT-ATES is applied in these aquifers. A proper water treatment, such as the addition of carbon dioxide or hydrochloric acid to the groundwater abstracted prior to heating, could be required to prevent groundwater from getting supersaturated with carbonate minerals.

How to cite: Dijkstra, H. E., de Boer, C. V., Koenen, M., and Griffioen, J.: Experimental risk assessment of carbonate scaling in the operation of high temperature – aquifer thermal energy storage (HT-ATES) systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9184, https://doi.org/10.5194/egusphere-egu2020-9184, 2020.

EGU2020-20414 | Displays | ERE2.8

Challenges in implementing energy geo-structures in developing markets: Evidence from Romania

Iulia Prodan, Horia Ban, and Octavian Bujor

Following the Directive 2010/31/EU on energy performance of buildings, EU state members have developed national plans for increasing the number of nearly zero energy buildings through measures that facilitate the implementation of renewable energy technologies. Due to this policies changes and also due to their incontestable advantages, energy geostructures are showing an increasing trend in number of implementations all across Europe. However, it is important that besides “good statistics”, the quality and efficiency of what is implemented to be ensured so that a real change is generated in terms of renewable energy exploitation and CO2 emissions reduction. The paper refers to challenges that are encountered in the process of implementation of energy geostructures especially on emerging markets for this technology, such as Eastern Europe, with emphasis on several case studies and evidence from Romania.

How to cite: Prodan, I., Ban, H., and Bujor, O.: Challenges in implementing energy geo-structures in developing markets: Evidence from Romania, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20414, https://doi.org/10.5194/egusphere-egu2020-20414, 2020.

ERE2.10 – Rethinking the energy transition in light of the Sustainable Development Goals: Maximizing synergies and minimizing trade-offs

EGU2020-18 | Displays | ERE2.10

Minimizing biodiversity trade-offs of future global hydropower reservoirs by strategic site selection

Martin Dorber, Anders Arvesen, David Gernaat, and Francesca Verones

The Sustainable Development Goals (SDG) require increased hydropower electricity production to reach SDG 7. However, a balance between related positive synergies and negative trade-offs needs to be found. So far there has been a strong focus on the technical development potential (SDG 7), and the positive synergies of hydropower, for example in relation to SDG 13 (Climate change). However, hydropower can also cause, for instance, biodiversity impacts, leading to a negative biodiversity trade-off with SDG 6 (Clean water and sanitation) and SDG 15 (Life on land). Although conservation of biodiversity has been identified as a key parameter for sustainable development, global assessments accounting for site specific biodiversity trade-offs of hydropower sites are still lacking.

To fill this research gap, we performed the first global and reservoir explicit assessment of terrestrial and aquatic biodiversity impacts of 2000 possible future hydropower reservoirs. We adapted the latest spatially explicit impact assessment methods available from the field of life cycle assessment, with a high-resolution and location-specific technical assessment of future economic hydropower potentials (Gernaat et al., Nature Energy 2017). More specially we collected site-specific environmental information from geographic information system databases to quantify potential reservoir-specific, net land occupation, net water consumption and methane emissions. Subsequently, we quantified the related terrestrial and aquatic biodiversity impact in units of potentially disappeared fraction of species (PDF).

Our results show that future hydropower electricity production can have a spatially highly variable biodiversity impact (varying by orders of magnitude) which can interfere with SDG 6 and SDG 15. Furthermore, we show that careful selection of reservoirs on a macro level has a large potential to limit biodiversity impacts. Thus, sustainable hydropower development requires an assessment of potential biodiversity impacts.  This in turn means, that if mitigating climate change for SDG 13 is the main motivation for increased hydropower production, as it can score favorable in studies comparing GHG emissions, it is likely that potential biodiversity impacts are overlooked. However, in order to move towards overall sustainability, taking biodiversity impacts into account next to climate change and other impacts, is of utmost importance.

How to cite: Dorber, M., Arvesen, A., Gernaat, D., and Verones, F.: Minimizing biodiversity trade-offs of future global hydropower reservoirs by strategic site selection, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18, https://doi.org/10.5194/egusphere-egu2020-18, 2020.

Sustainability trade-offs in the spatial allocation of future onshore wind generation capacity – an empiric case study for Germany

Abstract

The expansion of renewable energies is a key requirement to the global climate protection efforts. However, renewables themselves can be associated with negative local effects. A prominent example is the deployment of wind energy. Different sustainability criteria – e.g. the mitigation of adverse impacts on human health and ecosystems and the generation costs for renewable electricity from wind power, may call for different spatial allocations of wind turbines. As the optimal siting of wind turbines differs with regard to the individual sustainability criteria, this can imply trade-offs between the different sustainability criteria.
Therefore we developed an approach to identify and quantify how significant these trade-offs potentially are and to what extent they depend on the spatial allocation of wind turbines as well as on the overall level of wind power deployment.
Based on a spatially explicit GIS modelling using high resolution wind speed, settlement and ecological data for Germany, we calculate the potential trade-offs. Using a set of more than 100,000 technically and legally potential sites for modern wind turbines across Germany in a greenfield approach, the numerical optimization of these data identifies on the one hand optimal sites for each sustainability criteria in an expansion scenario for 2030. These different optimal spatial allocations can then be compared against each other for a basic trade-off analysis. Additionally, the trade-off analysis can be elaborated by the calculation of pareto-frontiers as well as a Gini-like coefficient that quantifies the potential trade-off between sustainability criteria in a paired comparison of sustainability criteria.
The results show that trade-offs are inevitable giving the required and projected capacity expansion for onshore wind power. But the potential trade-offs among the different sustainability criteria differ significantly with Gini-like coefficients ranging from 0.13 up to 0.69 for depending on the selected criteria in a paired comparison. This underlines that the approach and the obtained results are highly relevant for the management of sustainability trade-offs in future.

In general, the developed approach covers multiple relevant criteria and provides a framework for the empirical analysis and assessment of trade-offs associated with any spatially relevant energy-infrastructure and sustainability criteria. The approach can also be transferred to other application where trade-offs between different sustainability criteria have to be investigated and managed. And finally, as performed for the case study region of Germany, the obtained results can likewise be reintroduced and visualized using GIS in order to verify and further assess the spatially explicit results.

 

Index Terms:  spatial planning, trade-offs, wind energy, GIS applications, integrated assessment, allocation optimization

How to cite: Tafarte, P. and Lehmann, P.: Sustainability trade-offs in the spatial allocation of future onshore wind generation capacity – an empiric case study for Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9651, https://doi.org/10.5194/egusphere-egu2020-9651, 2020.

EGU2020-17631 | Displays | ERE2.10 | Highlight

The role of ‘living laboratories’ in unlocking the potential of renewable energy and smart distributed energy systems to address the UN SDGs

Chris Fogwill, Zoe Robinson, David Healey, Sharon George, Phillip Catney, Mark Omrod, Zhong Fan, Helen Glanville, Jun Cao, Ben Davenward, Peter Matthews, Ash Hulme, Ash Dean, and Ian Shaw

The UN Sustainable Development Goals provide a framework towards a more sustainable future.  Although each goal can be targeted separately, the greatest benefit is to be had in ensuring that projects exploit synergies between different goals, are developed with an interdisciplinary perspective, and integrate different stakeholders across academia, business, government, NGOs, and communities.

In combination, Renewable Energy Systems (RES) and distributed ‘smart’ energy networks (SEN) provide opportunities to drive down CO2 emissions, clearly addressing SDG13, ‘climate action’.  However, significant potential exists to positively contribute to a wider suite of goals as well as the potential to negatively impact other aspects. Addressing these tensions and opportunities requires development of a detailed understanding of the full societal, economic and environmental impacts of such developments.

Such integrated renewable energy systems and smart energy networks are in the early stages of development.  Taking a ‘living laboratory approach’ enables the development and live-testing of new energy systems, including the opportunity to consider full life cycle assessment impacts and benefits, as well as investigate and co-develop interactions with end-users.  Here we outline the potential of one of Europe’s largest ‘at scale’ multi-vector smart energy systems, developed as a ‘living laboratory’ at Keele University in the UK, to demonstrate an integrated approach to addressing the UN’s SDGs through integrated RES-SEN systems. The scale and scope of the project provides the opportunity for the detailed analysis required to provide a model of a scalable, integrated RES-SEN approach as part of an evolving energy landscape, where multi-vector renewables, and distributed energy and storage provide new models for decarbonisation, whilst also contributing more widely to the UN’s SDGs.

This project represents an ambitious and innovative demonstrator programme that brings together multiple stakeholders to explore the potential for addressing the core SDGs of ‘climate action’, ‘affordable and clean energy’, ‘sustainable cities and communities’, ‘decent work and economic growth’, and ‘industry, innovation and infrastructure’, while exploring the additional potential impacts and benefits to ‘quality education’, ‘life on land’ and ‘partnerships for the goal’. The programme of work focusses on technical developments, societal adoption and full economic life-cycle assessment, which combined are developing a blue print for the integration of RES-SEN technologies across the evolving energy landscape by working in partnership with key industrial and commercial partners to contribute to a wide array of the UN’s SDGs.  

 

How to cite: Fogwill, C., Robinson, Z., Healey, D., George, S., Catney, P., Omrod, M., Fan, Z., Glanville, H., Cao, J., Davenward, B., Matthews, P., Hulme, A., Dean, A., and Shaw, I.: The role of ‘living laboratories’ in unlocking the potential of renewable energy and smart distributed energy systems to address the UN SDGs , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17631, https://doi.org/10.5194/egusphere-egu2020-17631, 2020.

EGU2020-10330 | Displays | ERE2.10

Water, land and climate nexus of electricity from biomass

Nariê Souza, Thayse Hernandes, Karina M. B. Bruno, Daniele S. Henzler, and Otávio Cavalett

Driven by the expected population growth, the world faces now the challenge of meeting energy demands of about 9 billion people on the next decades and avoid dangerous climate change effects. In this context, Renewable Energy Systems (RES) are a key strategy to decarbonize the power sector and contribute to the climate change mitigation targets. In the Special Report on Climate Change and Land, IPCC calls attention to possible trade-offs, adverse side-effects and implications to sustainable development that the large-scale deployment of bioenergy may cause. A comprehensive understanding of the sustainability profile along the entire life-cycle of electricity production is fundamental if we want to realize the transition to cleaner technologies in the energy sector. In this study we analyze the water, land and climate impacts of electricity production systems in the context of the Sustainable Development Goals (SDGs). We focus our analysis in the electricity production from sugarcane straw in Brazil, since there is a great opportunity for better using this lignocellulosic material for bioenergy applications. We relate appropriate Life Cycle Assessment (LCA) indicators to multiple SDGs, considering attainable and potential sugarcane yields, derived from agroclimatic modeling. When discussing the sustainability of bioenergy production, a broader sustainability analysis, as provided by the SDGs, can help to identify water, land and climate nexus and suggest possible technological solutions for minimizing possible trade-offs among the different impacts. Our analysis demonstrates the nexus implications of electricity production from sugarcane biomass to the context of the SDGs, as well as the spatially explicit environmental implications of electricity production form sugarcane biomass.

Keywords: renewable energy systems, life cycle assessment, climate change mitigation, sustainable development

How to cite: Souza, N., Hernandes, T., Bruno, K. M. B., Henzler, D. S., and Cavalett, O.: Water, land and climate nexus of electricity from biomass, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10330, https://doi.org/10.5194/egusphere-egu2020-10330, 2020.

EGU2020-687 | Displays | ERE2.10

Can SDG Acceleration Actions promote the key SDGs?

Ting Hua and Wenwu Zhao

Through the promotion of the past five years, some positive signs have emerged in the progress of some SDGs. However, there is still a large gap between the speed and scale of sustainable transition compared to the extent needed to achieve the SDGs in 2030. United Nations has called on governments and international organizations to propose appropriate SDGs Acceleration Actions to reverse the current unfavorable situation. But before moving forward to more actions, it is important to know which SDGs are urgently needed to be addressed and the matching between the existing actions and priority needs. In this study, we attempt to reveal the SDGs that need to be focused on in promoting SDG Acceleration Actions in terms of expert inquiries, the current sustainable development level, the relationship among 17 SDGs, and the comparison between planetary boundaries and SDGs. We found that there is an obvious conflict between the boost of the SDGs and the control of the biophysical boundaries. And if considering achieving sustainability within the planetary boundaries, we should focus on SDG2, SDG9, SDG14, SDG15, the conflict between these SDGs and multiple biophysical indicators such as CO2 emissions needs to be reconciled, and the gap between average and highest efficiency utilization efficiency needs to be narrowed. Compared to our results, existing actions are not enough for the key SDGs we screened. This study could be a step forward to optimizing the overall arrangement of SDG Acceleration Actions and implementing SDG policy effectively.

Keywords: Sustainable Development Goals (SDGs); SDGs Acceleration Actions; Planetary Boundaries; Sustainability

How to cite: Hua, T. and Zhao, W.: Can SDG Acceleration Actions promote the key SDGs?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-687, https://doi.org/10.5194/egusphere-egu2020-687, 2020.

EGU2020-6579 | Displays | ERE2.10

Urban densification potentials and energy impacts in Switzerland

Sven Eggimann and Kristina Orehounig

Building sustainable cities, as set out in the Sustainable Development Goals by the UN, requires sustainable urbanization as well as reducing per capita environmental impacts of living in cities. As a result of a growing population and constrained availability of building space, countries such as Switzerland are faced with increasing pressure on their land resources. They will need to considerably densify in existing urbanized areas to prevent urban expansion. Even though Swiss regulation promote inward settlement development and the creation of compact settlements, only limited analysis is available on the densification potentials combined with sustainability implications. We develop a geospatial explicit analysis framework which allows to up-scale the assessment and evaluation of densification potentials for the whole of Switzerland. An energy simulation tool is used for exploring impacts of different densification strategies on a district scale with respect to energy consumption.

How to cite: Eggimann, S. and Orehounig, K.: Urban densification potentials and energy impacts in Switzerland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6579, https://doi.org/10.5194/egusphere-egu2020-6579, 2020.

Since GTGP (Grain to Green Project) has implemented in 1999, soil erosion and vulnerable habitat have substantially improved along with the enhancement of human living standards. Under vision of Sustainable Development Goals (SDGs), how residents evaluate sustainable development status plays important role in regulating objectives of the policy. Yet, few researches involved. In this study, we conducted interview survey to investigate the subjective viewpoints on SDG and ES. Overall, we collected 667 valid questionnaires from 13 counties (districts) in Yan’an city. Results indicated that environmental quality has been improved, which included improvement of water quality, amelioration of soil erosion, increase of vegetation types and spiritual acquirement, as well as maintenances of species diversity habitat quality. As for living standard, although respondents’ a grain output decreased, the income not decreased because of ecological compensation. Besides, farmers can increase their income by engaging in the tertiary industry. With regards to SDG awareness, there are trade-off between protecting biodiversity (SDG 15) and economic growth (SDG 8). In addition, farmers' awareness of environmental protection and social responsibility have been significantly strengthened. We conclude that, although perceptions of ES have showed a significant improvement, there are still gaps hindering achievement of regional SDGs, which reflected by lacking collective identification on economic and environment aspects.

How to cite: zhou, A. and Zhao, W.: Residents' awareness of Sustainable Development Goals (SDGs) after Grain to Green Project implementation in Loess Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-905, https://doi.org/10.5194/egusphere-egu2020-905, 2020.

EGU2020-10478 | Displays | ERE2.10

Environmental performance of grate furnace and fluidised bed furnace systems to produce electricity from forest biomass residues

Paula Quinteiro, Tamíris Pacheco da Costa, Luís Tarelho, Luís Arroja, and Ana Cláudia Dias

Electricity production from biomass has the potential to significantly contribute to the share of renewable energy in the global power mix with lesser environmental impact than non-renewable resources. The production of bioenergy from forest biomass residues is currently increasing in Portugal, mainly as a consequence of concerns related to climate change and forest fires.  In Portugal, the annual production of residual biomass from forest logging is estimated at 0.8-1.2 million dry tons per year, and about 47-58% of these residues come from eucalypt. 

This study evaluates the environmental impacts resulting from electricity production in Portugal using eucalypt logging residues (composed of branches, foliage and tops) and considering two types of technologies: grate furnaces and fluidised bed furnaces. This assessment was performed using life cycle assessment (LCA) methodology, a methodology that evaluates the environmental impacts entire life cycle of a product or process (from the extraction of the raw materials until its end-of-life), allowing to identify the most significant stages and processes along the life cycle, and supporting by this way the decision and policy-making.

Two alternative scenarios for biomass-to-energy conversion technologies were simulated: grate furnace and fluidised bed furnace. The functional unit is the production of electricity from the combustion of eucalypt logging residues equivalent to 1 kWh delivered by the power plant to the Portuguese grid. System boundaries include the following stages: (1) forest management (including site preparation, planting, stand tending and logging); (2) residues collection; and (3) energy conversion (including forest biomass combustion as well as treatment and final destination of wastes). Seven impact categories from the International Reference Life Cycle Data System (ILCD) are considered: climate change, particulate matter, photochemical ozone formation, acidification, freshwater eutrophication, marine eutrophication and mineral and fossil resource depletion.

The results show that the forest management stage had a low contribution to the total impact in all impact categories for both technologies under analysis. The only exception is the impact category of mineral and fossil depletion, in which forest management is mainly responsible and which accounts for 92-94% of the total impact for both technologies analysed. The energy conversion is the hotspot in most of the impacts studied (climate change —49-63%, particulate matter —94-95%, photochemical ozone formation —85-88% of, acidification —76-79%, freshwater eutrophication —56-58% and marine eutrophication —70-71% of the total impact) and therefore, this is the stage for which improvements should be primarily establishedestablished for both technologies analysed. In addition, for all impact categories analysed, the fluidised bed presented the smallest environmental impact. Even when the grate furnace efficiency increases and the fluidised bed efficiency decreases in a sensitivity analysis, the fluidised bed has lower impacts than the grate furnace and is a good alternative for implementing new power plants. Further research is needed to analyse the effects of converting the grate technology in Portugal to fluidised bed technology.

How to cite: Quinteiro, P., Pacheco da Costa, T., Tarelho, L., Arroja, L., and Cláudia Dias, A.: Environmental performance of grate furnace and fluidised bed furnace systems to produce electricity from forest biomass residues, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10478, https://doi.org/10.5194/egusphere-egu2020-10478, 2020.

Tibet Plateau plays an important role in protecting the ecological security of China and even Asia, to ensure its normal and effective ecosystem function, a series of ecological security barrier protection and construction projects have been implemented. The sustainable development goals(SDGs) of the United Nations can provide a broad framework for optimizing and coordinating the ecological security barrier protection and construction projects. The public to the understanding of ecological security barrier projects and sustainable development goals can influence their decision making and participation. We determine public understanding of the projects through its contribution to SDGs. Using the results of department questionnaire in Linzhi City (n=176), we identified nine projects contribution to sustainable development goals and different cognitive patterns for them. Soil and water loss control project and sand control project have more contributions to SDSs , while the contributions of returning grazing to grassland and pest control project and traditional energy substitution project in agricultural and pastoral areas to SDGs are relatively small. Soil and water loss control project is to realize the basic requirements and management goals largest contributor, sand control project is the largest contributor to achieving the expected goals. From the cognitive patterns we see individual differences in participants, but the dominant cognitive patterns among individuals are identified. We put forwards suggestions for optimizing ecological security barrier projects to promote the achievement of the United Nations Sustainable development goals.

How to cite: Liu, X. and Zhao, W.: Public views of ecological security barrier projects contributions towards sustainable development goals in Tibet plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-914, https://doi.org/10.5194/egusphere-egu2020-914, 2020.

EGU2020-2863 | Displays | ERE2.10

Classification–coordination–collaboration: A system approach for advancing sustainable development goals

Junze Zhang, Bojie Fu, Shuai Wang, and Wenwu Zhao

The 17 Sustainable Development Goals (SDGs) provide a blueprint for the world’s sustainable development plan throughout 2016 and 2030. It is regrettable that recent reports have shown that it will not be possible to achieve all the goals by 2030 under our current pace. To accelerate SDG implementation, scientists have conducted studies under a variety of perspectives, such as relationships among SDGs, their specific priorities, and necessary transformations. However, there still lacks a systematic approach to promote joint action by countries that can advance SDGs on regional, national, and global scales. To fill this gap, we summarize the relevant articles, reports, and practices in recent years on the ways to promote the implementation of the SDGs. Following this, we propose a systematic approach to combat this issue, namely, “classification–coordination–collaboration”. This approach not only considers relationships among the 17 SDGs and the links among the different management agencies, but it also contains the necessary means to accelerate SDGs. Overall, this approach is expected to promote the participation of countries within the process of global governance, and it will help to ensure that SDGs will realize key breakthroughs over the short-term while achieving sweeping progress over the long run.

How to cite: Zhang, J., Fu, B., Wang, S., and Zhao, W.: Classification–coordination–collaboration: A system approach for advancing sustainable development goals , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2863, https://doi.org/10.5194/egusphere-egu2020-2863, 2020.

EGU2020-19428 | Displays | ERE2.10

Potential contribution from bioenergy with CCS to SDG13: an Earth system modelling perspective

Helene Muri, Jan Sandstad Næss, and Cristina Maria Iordan

Renewable energy will play a key role in tranformation of the energy sector to reduce CO2 emissions. Integrated Assessment Modelling scenarios reaching the temperature targets of the Paris Agreement rely on large scale deployment of Bioenergy with Carbon Capture and Storage (BECCS). BECCS are a key contributor to reducing emissions and acheiving net negative emissions in such scenarios. The potentials of large scale BECCS deployment in reaching the 1.5°C target is evaluated using Earth system model simulations in the work presented here. Fully coupled carbon cycle and interactive biogeochemistry is used to assess different rates of BECCS deployment, alongside assuming strong mitigation. BECCS at large scale influence not only the global carbon cycle, but also the feedbacks between the atmosphere and land surface. Changing the land cover to biocrops affects the terrestrial store of carbon, and also the physical properties of the land surface, i.e. biogeophysical forcing, which leads to important feedbacks in the climate system. Renewable energy from BECCS may have implications on several of the SDGs, in particular #13 Climate, #7 Energy, #15 Life on land, as well as #2 Hunger. It is found that it remains a challenge to achieve the 1.5°C target, relying strongly on bioenergy with CCS, and the mitigation potential depends on geografical location, and availability of suitable land areas.

How to cite: Muri, H., Næss, J. S., and Iordan, C. M.: Potential contribution from bioenergy with CCS to SDG13: an Earth system modelling perspective, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19428, https://doi.org/10.5194/egusphere-egu2020-19428, 2020.

SDGs can be better achieved when more firms are willing to fulfill their CSR and disclose their CSR information. Stakeholder theory argues that corporate stakeholders are one of the most critical driving forces for corporations’ willingness to fulfill their CSR and disclose their performance in CSR. Due to the global trend of advocating sustainable development and green consumerism, more and more corporate stakeholders incorporate enterprises’ efforts in CSR into their investment/procurement decisions. For example, KPMG's survey (2017) indicated that stakeholders had started to view the environmental and social issues such as climate change, water scarcity, and human rights as financial issues rather than non-financial issues. Therefore, corporate stakeholders are incentivized by the global concerns of sustainable development to demand corporations’ disclosure of CSR information and, then, the corporations are incentivized by stakeholders to fulfill their CSR and report the results.

However, currently, CSR information is mainly reported by large or international firms. The key to the success of CSR disclosure scheme is for all firms, mostly small to medium enterprises (SMEs), to be willing to disclose. Nevertheless, many obstacles prevent SMEs from fulfilling CSR. The most concern for SMEs is the costs and efforts. SMEs do not know what to do and what to disclose and, thus, they imagine that CSR is a costly, heavy burden. Therefore, it is critical for firms to have better strategies for efficient and effective disclosure of CSR.

In this study, we argue that the content and extent of the disclosed information should be aligned with stakeholders’ desired information. Furthermore, we argue that the strategies for CSR reporting should be sector-specific because stakeholders in different sectors desire different sector-specific CSR information that is associated with sector-specific characteristics and impacts on sustainability.

In terms of methodology, we identify the “Topics” and Topic-specific “Disclosures” (according to GRI Standards) that are most disclosed in the CSR reports of the top corporations of that sector. Because the top corporations face the most attention from their stakeholders, the current CSR information disclosed by these top corporations can serve as the reference for forming “effective” CSR reporting strategies. Thus, the first step of the methodology is to obtain sector-specific statistics based on the top corporations of that sector.

For developing “efficient” CSR reporting strategies, we differentiate the “Topics” and Topic-specific “Disclosures” into three Groups based on their disclosing rates, which are calculated by how many firms among the referenced/sample corporations disclose each Topic and its associated Disclosures. The three groups provide different sizes of firms different minimum (i.e., efficient) numbers of Topics/Disclosures reported, which reflect mainly the sector-specific characteristics. Therefore, the second step of this methodology is to differentiate the relevant Topics/Disclosures into three Groups. The third and last step is to analyze the information in each Group and to form the sector-specific strategies for CSR reporting based on the insights obtained from the analyses. Strategies developed using this methodology will be proposed. We shall apply this methodology to the international construction sector.

How to cite: Ho, S. P. and You, C.-Y.: Better Achievement of SDGs Through Developing Better Firm Strategies for Efficient and Effective Disclosure of Corporate Social Responsibility, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20878, https://doi.org/10.5194/egusphere-egu2020-20878, 2020.

ERE3.1 – Petroleum exploration and production and their impact on the environment

EGU2020-99 | Displays | ERE3.1

Prospects for oil discovery in the Rhine Rift (Germany)

Yuri Galant, Yuri Pikovskiy, and Pavel Čížek
  • The work was initiated with the aim of assessing the prospects of the Rhine Rift oil potential. The search technique was based on the analysis in basalts of Polycyclic Aromatic Hydrocarbons (PAH) which are an indicator of the oil content of deep horizons. Samples of Rocks were taken from Quarry and Outcrops. PAH analysis was carried out at Moscow State University. All samples contain PAH. 11 components detected. The total amount of the components is 0.052834 mg / kg. Rate of 4 components: Naphthalene and homologous, Phenantren, Difenil, Benz (ghi) perylene is equal more a half of all components (58%). Our study revealed the typical association of PAH, which are characteristic of the oil fields: Phenanthrene, Chrysene, Pyrene, Benz(a)pyren. PAH provide evidence of probable former generation and migration of endogenous hydrocarbons. Existence such components as Phenanthrene, Chrysene, Pyrene, Benz(a)pyren pointed on migrations of Hydrocarbons from depth - (From Oil - deposit?). Samples analyzed show on the existence Hydrocarbons migrations of gases and a more Heavy Hydrocarbons. Favorable geological settings of Rhine Rift, such as seismic activity, new tectonic movements, and presence of Basalt, decompressed rocks of mantle, rift stretching mode, and favorable geochemical indications, such as existence of typomorphic oil-associated PAH (Phenanthrene, Chrysene, Pyrene, Benz(a)pyren), presence the components resembling on compositions of Moravia oil, are positive factors for oil discovery in the Rhine Rift. Data received can serve as base for set detail works for seeking cluster of oil! And in the first instance at areas: Bad Urah, Kaizertuhl-Shellingen.

How to cite: Galant, Y., Pikovskiy, Y., and Čížek, P.: Prospects for oil discovery in the Rhine Rift (Germany), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-99, https://doi.org/10.5194/egusphere-egu2020-99, 2020.

EGU2020-249 | Displays | ERE3.1

Effects of pore-throat structure on reservoir blockage and wettability alteration during CO2 injection

Qian Wang, Paul Glover, and Piroska Lorinczi

Injection of CO2 into subsurface reservoirs occurs during Enhanced Oil Recovery (EOR) and also during Carbon Capture and Storage (CCS) operations. During CO2 injection, the efficacy and distribution of fluid flow in sandstone reservoirs is controlled by the pore-throat microstructure of the rock. Furthermore, CO2 injection promotes asphaltene precipitation on the pore surface and can also affect fluid flow in the pore throats, decreasing the permeability and altering reservoir wettability. In this work, miscible and immiscible CO2 flooding experiments under reservoir conditions (up to 70℃, 18 MPa) have been carried out on four samples with very similar permeabilities but different pore-throat structures in order to study the effects of pore-throat microstructure on formation damage. The features of pore-throat structure were evaluated by fractal theory, based on pore size distributions and rate-controlled porosimetry (RCP) mercury intrusion curves. Reservoir rocks with smaller pore throat sizes and more heterogeneous and poorer pore-throat microstructures were found to be more sensitive to asphaltene precipitation, with corresponding 15-20% lower oil recovery and 4-7% greater decreases in permeability than that of rocks with homogeneous and better pore-throat microstructure. However, the water-wettability index of cores with larger and more connected pore-throat microstructures was found to drop by an extra 15-25% than heterogeneous core due to more asphaltene precipitation caused by the larger sweep volume of injected CO2 they consequently experienced, which is a disadvantage for EOR. In addition, immiscible flooding exacerbates the differences from 4-7% to 8-15% in permeability decline of the rocks with different pore-throat structures. Miscible flooding leads to more asphaltenes being precipitated from the crude oil, triggering in average an extra 11% change in wettability in comparison to immiscible flooding.

 

Keywords: CO2 flooding, asphaltene precipitation, pore size distribution, pore-throat microstructure, reservoir blockage, wettability alteration

How to cite: Wang, Q., Glover, P., and Lorinczi, P.: Effects of pore-throat structure on reservoir blockage and wettability alteration during CO2 injection, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-249, https://doi.org/10.5194/egusphere-egu2020-249, 2020.

This study investigates the pathway of secondary oil migration which leads to the oil accumulation in Dongying Depression using basin modeling and pyrrolic nitrogen compounds. Modeling of oil migration pathways have been conducted for the third and fourth member (Es3&Es4) of Shahejie Formation including the reconstruction of burial history, thermal maturation and hydrocarbon generation processes, which are calibrated by parameters of pyrrolic nitrogen compounds and further reinforced by distributions of oil wells and fields. Carbazole parameters, such as 1-/4-methylcarbazole (1-/4-MC), 1,8-/2,7-dimethylcarbazole (1,8-/2,7-DMC) and benzo[a]carbazole/(benzo[a]carbazole + benzo[c]carbazole) ([a]/[a] + [c]) are presented to trace the oil migration pathways. The investigated 38 oil samples can be classified into three groups considering the effects of biodegradation, thermal maturation and the variation in source facies. The group I oils are derived from the lower interval of Es3, the group III oils are originated from the upper interval of Es4, and the group II oils are admixing of the source-rock intervals of Es3 and of Es4. Nine migration pathways can be determined using the abovementioned carbazole parameters. In specific, ratios of 1-/4-MC and 1,8-/2,7-DMC increase and [a]/[a] + [c] decreases as the increasing of oil migration distance. Meanwhile, the oil migration pathways resulted from basin modeling are in good agreement with those determined by pyrrolic nitrogen compounds. Most of the investigated oil wells and fields are located on the predicted migration pathways. In a nutshell, two favorable oil accumulation areas have been predicted along the migration pathways of oil in the Es4 member of Dongying Depression.

How to cite: Chen, J. and Guo, X.: Combination of basin modeling and pyrrolic nitrogen compounds to investigate the secondary oil migration pathway in the Dongying Depression of Bohai Bay Basin, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1980, https://doi.org/10.5194/egusphere-egu2020-1980, 2020.

The Jianghan Basin is a typical eastern fault depression salt lake basin in China, in which the Paleogene strata of the Qianjiang Sag are rich in shale oil resources. As a salt lake sedimentary basin, the developed Qianjiang Formation is a set of inter-salt oil-bearing strata, in which the salt rock strata are especially developed. There are many salt rhythms in the study area and a salt rhythm consists of a argillaceous dolomite layer between a salt rock formation and a salt rock formation. This study focuses on the 10th rhythm of the Qian 34 section of Qianjiang Depression (Eq3410). The samples were investigated by organic geochemical analysis and X-ray diffraction, and the pore structure characteristics of the reservoir were studied by argon ion polishing scanning electron microscope and low temperature nitrogen adsorption test. The research indicates that the average TOC of Eq3410 in Qianjiang Depression is 2.11% and the main distribution is 1%~3%; the type of organic matter is mainly Type II2 and Type II1; the overall maturity of organic matter is low maturity stage(Tmax is 412~441℃with an average of 423℃). The XRD data indicates that the mineral composition of the Qianjiang Formation shale oil reservoir is complex and have strong heterogeneity(quartz content in 2.3%~18.6% with an average of 9.5%, calcite content in 6.9~43.8% with an average of 12.8%, dolomite content in 2.5%~ 61.2% with an average of 27.2%, clay mineral content in 1.0%~45.2% with an average of 20.5%, glauberite content from 7.1% to 92.7% with an average of 22.9%). The pore types of shale oil reservoirs in Qianjiang Sag are complex and diverse and mostly are intergranular pores, which are mainly developed between detrital minerals or between detrital minerals and carbonate minerals. In carbonate mineral particles and quartz particles, some intragranular pores are visible, including calcite dissolution pores, internal pores of calcite and clay minerals, and internal pores of pyrite particles. And organic pores are rare in reservoirs due to the low maturity(Ro ranges between 0.5% and 0.7%). Nitrogen adsorption experiments showed that the pore size distribution of Eq3410 samples was dominated by mesopores and macropores. And the pore volume of the Eq3410 sample was most affected by the macropore pore volume, averaging 66.22%, followed by the mesopore pore volume with an average of 31.45%. To study and understand the characteristics of shale oil reservoir in Qianjiang Depression is conducive to mastering the regularity of shale oil enrichment and provides a basis for the exploration and development of shale oil.

How to cite: Luo, J. and Wang, F.: Characteristics of shale oil reservoirs in Qianjiang Formation, Qiangjiang Depression, Jianghan Basin, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1982, https://doi.org/10.5194/egusphere-egu2020-1982, 2020.

Water /gas mobility and interaction in coal plays an important role in achieving the high performance of coalbed methane (CBM) recovery. A large volume of fracturing fluid is permeated into reservoir during the CBM development. The effect of the imbibed liquid on gas recovery is still controversial. To better understand this phenomenon, a systematical investigation of water dynamic imbibition and matrix permeability change during water imbibition were conducted experimentally using different coals collected from Qinshui, Ordos and Junggar Basin of China.

The research stimulates two different case of spontaneous imbibition and the special imbibition process and imbibition in different pores are concluded by analyzing the imbibition characteristics (i.e. imbibition ability, imbibition rate and imbibition dynamic). The water imbibes into smaller pores and larger pores simultaneously, in which the water imbibition rate is relevant to the porosity, permeability and wettability. The water imbibition in coal matrix can bring about the redistribution and existing state change of water, which probably one of the main factors causing the damage of the matrix permeability. By studying the permeability change and imbibition law, a permeability model is used to explain the influence of imbibition on permeability. Finally, the permeability is found as a function of sorting time and invasion depth, which will be useful for field applications.

How to cite: Chang, Y.: Water Imbibition of Coal and its Potential Influence on CBM Recovery, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2893, https://doi.org/10.5194/egusphere-egu2020-2893, 2020.

EGU2020-3882 | Displays | ERE3.1

Determination of formation paleo-pressure and evolution process using gaseous hydrocarbon inclusions

Cunjian Zhang, Jingdong Liu, and Youlu Jiang

Research on overpressure evolution and its formation mechanisms is of great significance for revealing reservoir formation mechanisms and predicting formation pressures in oil and gas reservoirs before drilling. However, research methods addressing overpressure evolution are not without issues. The fluid inclusion PVT simulation and basin simulation can be used to investigate the paleo-pressure.

The homogenization temperatures of inclusions were tested. The accuracy of the microscopic laser Raman spectroscopy analysis is too limited to fully test the components of gaseous hydrocarbon inclusions so that the organic components of the natural gas in the present-day gas reservoirs represented the gaseous hydrocarbon inclusions. In addition, the vapor-liquid ratio of gaseous hydrocarbon inclusions cannot be measured by CLSM. Firstly, A series of images at different slice depths was obtained by adjusting the focal length of a high-resolution microscope. Secondly, CorelDRAW software was used to calculate the areas of inclusions and bubbles; fitting functions were established between the inclusion areas and slice depths, and between the bubble areas and slice depths. Finally, the inclusion and bubble volumes were integrated to obtain the vapor-liquid ratios of the inclusions. PVTsim software can calculate the trapping pressures of inclusions. Combined with basin simulation, the evolution of paleo-pressure can be determined.

The above methods were used to investigate the paleo-pressure of the Upper Triassic Xujiahe Formation in the northeast portion of the Sichuan Basin. Overpressure began to develop in the Middle Jurassic period. Due to hydrocarbon generation taking place, the formation pressure increased rapidly from the Middle Jurassic period to the early Late Cretaceous period. Since the early Late Cretaceous period, the formation pressure has gradually decreased due to tectonic uplift and erosion. From the Oligocene period to the present, the formation pressure have increased again in local areas due to tectonic compression.

How to cite: Zhang, C., Liu, J., and Jiang, Y.: Determination of formation paleo-pressure and evolution process using gaseous hydrocarbon inclusions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3882, https://doi.org/10.5194/egusphere-egu2020-3882, 2020.

EGU2020-22681 | Displays | ERE3.1

Experimental Determination of the Shale Wettability

Aliya Mukhametdinova, Natalia Bogdanovich, Alexey Cheremisin, and Svetlana Rudakovskaya

In recent years, the share of unconventional reserves in global oil production has grown. Exploration and development of unconventional resources require novel effective laboratory methods for characterizing the reservoir properties. The study and analysis of local shale deposits such as Bazhenov Formation (BF) in Western Siberia is a priority among non-traditional reservoirs. Wettability of the reservoir rock is one of the most important factors affecting the residual saturation and filtration properties in the formation. However, as multiple petrophysical studies show, conventional laboratory methods for characterizing the wettability are not applicable for this type of formations.

In this work, the fluid saturation and wettability of BF rock samples were studied utilizing a nuclear magnetic resonance (NMR) and the method of determining the wetting contact angle by a surface drop. We have provided the petrographic description of rocks using ultrathin sections for grouping the samples. In addition, we used data on the organic content (TOC) obtained by the Rock-Eval method on a HAWK RW instrument (Wildcat Technologies) and the results of lithological typing on thin sections using an Axio Imager A2m polarizing microscope (Carl Zeiss) for detailed analysis of NMR and contact angle methods results.

To assess wettability by NMR, T2 relaxation curves were constructed for extracted (cleaned), kerosene-saturated and water-saturated samples. A comparison of the relaxation spectra for kerosene and water enabled evaluation of the wettability for each by T2 log mean values. The calculation of the wetting angle was carried out for samples before and after the extraction, which revealed minor changes in the nature of the rock wettability because of cleaning. Thus, for this type of rock, the drop method for determining wettability turned out to be significantly sensitive to the shape of the OM distribution in the rock. Correlations built on wettability (by NMR results and calculated wetting angle) vs. TOC and lithotyping illustrated the dependence of rock wettability behavior on both the lithotype and the TOC content.

The calculation of the wetting angle provided an initial assessment of the surface wettability of the rock and made it possible to establish the relationship between the wetting angle and the content of organic carbon (TOC), which is relevant for BF rocks. The lithological description of thin sections was used to highlight groups with a similar wettability of the rock. For the integral characteristics of the samples wettability, the NMR relaxometry method was proposed.

How to cite: Mukhametdinova, A., Bogdanovich, N., Cheremisin, A., and Rudakovskaya, S.: Experimental Determination of the Shale Wettability, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22681, https://doi.org/10.5194/egusphere-egu2020-22681, 2020.

A new method has been developed for modeling acoustic monitoring of a layered-block elastic medium with several inclusions of various physical, mechanical and phase hierarchical structures. An iterative process is developed for solving the direct problem for the case of three hierarchical inclusions of l, m, s-th ranks based on the use of 2D integral-differential equations. The degree of hierarchy of inclusions is determined by the values ​​of their ranks, which can be different. Hierarchical inclusions are located in one layer: the first is anomalously dense, the second is anomalously plastic, and the third is anomalously elastic and fluid-saturated density. The degree of filling with inclusions of each rank for all three hierarchical inclusions is different. The simulation results can be used in monitoring studies of the control of fluid return from oil fields developed as part of horizontal drilling.

 

How to cite: Khachay, A.: Algorithm for 2D Modeling of the Propagation of a Sound Wave in an N-layer Elastic Medium with Inclusions with Various Physical-Mechanical Properties of a Hierarchical Type Located in an Oil Reservoir, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1324, https://doi.org/10.5194/egusphere-egu2020-1324, 2020.

The stratum of Qingxudong Formation (Longwangmiao Formation) in Southern Sichuan-Northern Guizhou is generally thin in the west and north, thick in the east and south. The thickness of the stratum is 100m-250m, which is missing only in ya’an-chengdu area. The Qingxudong Formation in the study area mainly develop restricted platform facies and open platform facies deposits. The northern to central part of the study area mainly develop restricted platform facies, which can be divided into mixed tidal flat, inner beach, inter beach lagoon and other subfacies. The lithology is dominated by micrite-aplite dolomite and bioclastic dolomite with a thin layer of mud crystal limestone, siltstone, etc. Bean grain limestone and oolitic limestone can be seen at the bottom. The limestone composition of the Qingxudong Formation in the study area gradually increase from north to south, and the lithology of the Qingxudong Formation in the Songlin-Yankong area is dominated by micritie-aplite limestone and granular limestone, followed by dolomite. Open platform facies are developed, which can be furtherly divided into subfaces such as intra-platform beaches and inter-shoal beaches. The reservoirs in intra-platform subfacies of the Qingxudong Formation in the southern Sichuan-northern Guizhou area are relatively developed. Due to the high terrain of the beach, the karstification is favorable. Secondly, later-stage burial dissolution tends to selectively dissolve multi-phase intergranular cements or fillers to form intergranular dissolution pores, providing a lot of storage space.The analysis about the reservoirs’ physical properties of different microfacies suggest that, the porosity of the granular beach microfacies reservoirs ranges from 0.29% to 7.32%, with an average of 3.3%; the matrix permeability ranges from 0.006×10-3μm2 to 0.043×10-3μm2,with an average of 0.014×10-3μm2. the porosity of Yunping microfacies reservoir ranges from0.56% to 7.25%, with an average of 2.9%; the matrix permeability ranges from 0.006×10-3μm2 to 0.027×10-3μm2, with an average of 0.01×10-3μm2.The porosity of other microfacies reservoir ranges from 0.08% to 2.65%, with an average of 1.22%; the matrix permeability ranges from 0.008×10-3μm2 to 0.01×10-3μm2, with an average of 0.009×10-3μm2. It can be seen that the intra-platform subfacies have a constructive effect on reservoir development, which is the basis of reservoir development.

Keywords: Southern Sichuan-Northern Guizhou; Qingxudong Formation; sedimentary facies; reservoir physical property; reservoir characteristics

How to cite: Yan, R. and Zhou, L.: The depositional characteristics of Cambrian Qingxudong Formation in Southern Sichuan-Northern Guizhou and its control effect on reservoir beds, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2421, https://doi.org/10.5194/egusphere-egu2020-2421, 2020.

EGU2020-3402 | Displays | ERE3.1

The coupled generation of organic acids and hydrocarbons during source rock maturation

Jian Chen, Jie Xu, Zhenyu Sun, Susu Wang, Wanglu Jia, and Pingan Peng

Introduction: Organic acids which are commonly detected in oilfield waters, can partially enhance reservoir properties. Previous studies have suggested that cleavage of the oxygen-containing functional group in kerogen is a major source of organic acids. However, this cleavage is assumed to occur before the source rock enters the oil window. If this is correct, then these acids can dissolve only minerals in the source rocks. Presently, no detailed study of the generation of organic acids during the whole thermal maturation of source rocks has been conducted. It is unclear whether organic acids could migrate into reservoirs.

Aim: This research simulated the thermal evolution of source rocks in order to build a coupled model of organic acid and hydrocarbon generation, and investigate if organic acids generated in source rocks can migrate into reservoirs.

Methods: Three immature source rocks containing type I, II, and III kerogens were crushed to 200 mesh. These powders, along with deionized water, were sealed in Au tubes and heated to 220–360°C for 72 h (EasyRo 0.37-1.16%). All the run products, including organic acids, gas, and bitumen, were analyzed.

Results: At all temperatures, the organic acids dissolved in the waters are composed of formate, acetate, propionate, and oxalate. Acetate is the major compound with a modal proportion of >83%. The maximum yield of total organic acids was from source rocks containing type I kerogen (31.0 mg/g TOC), which was twice that from source rocks containing type II and III kerogens (13.3–15.4 mg/g TOC). However, for the type I and II kerogen-bearing source rocks, the organic acids reached a maximum yield (EasyRo = 1.16%) following the bitumen generation peak (EasyRo = 0.95%). Organic acids from type III kerogen-bearing source rocks reached their maximum yield (EasyRo = 0.95%) before the source rock entered the gas window (EasyRo > 1.16%).

Conclusions: Our data suggest that the generation of organic acids is coupled with the generation of oil from type I and II kerogen-bearing source rocks, but form earlier than gas from type III kerogen-bearing source rocks. As such, some organic acids dissolved in pore waters are possibly expelled from source rocks containing type I and II kerogen with oils, which can then migrate into reservoirs. Migration of organic acids into reservoirs from source rocks containing type III kerogen is also possible in some situations. For example, when a source rock is rapidly buried for a short period, such as in the Kuqa Depression, Tarim Basin, China, the generation interval of organic acids and gas is short. Both could be expelled outside and migrate upwards into reservoirs. In conclusion, organic acids derived from source rocks can contribute to reservoir alteration.

How to cite: Chen, J., Xu, J., Sun, Z., Wang, S., Jia, W., and Peng, P.: The coupled generation of organic acids and hydrocarbons during source rock maturation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3402, https://doi.org/10.5194/egusphere-egu2020-3402, 2020.

The geochemical characteristics and source of natural gases in the northern Subbasin, Bohai Bay Basin, eastern China are investigated systematically by the chemical components, stable isotopic compositions, noble gases isotopic compositions, and geochemical characteristics of associated oils. The results show that several genetic gases are identified in the study area, including thermogenic gas (sapropelic and humic gas), biogenetic gas (primary and secondary microbial gas) and mixed gas. Gases in the shallow strata (Ed, Es1, Es2, Es3 and some Es4 samples) are mainly oil-associated gases, whereas the gases in the deep strata (some Es4 samples, C-P and O) are mainly coal-derived gases and mixed-source gases. Some microbial gases including primary and secondary microbial gases can be identified in shallow Es1 and Es3 reservoirs. The carbon dioxide reduction under anaerobic conditions may be responsible for the anomalously heavy carbon isotope in carbon dioxide and light carbon isotope in methane in the biodegradation gases from the shallow strata (<1900 m), whereas carbon dioxide with heavy isotope compositions in the deeply buried Ordovician reservoirs may be the production of strong acids react with carbonate rocks during acidification and fracturing. The oil-associated gases in shallow strata are derived primarily from the Paleogene Es3 and Es4+Ek bearing sapropelic organic matters, whereas the coal-derived gases in the relatively deep reservoirs are mainly derived from the Paleozoic C-P coal-bearing source rocks and mixed organic matters in Es4+Ek. In addition, the dry gas (secondary cracking gas) in deep to ultra-deep carbonate reservoir may be the potential and favorable exploration field.

How to cite: Liu, N. and Qiu, N.: Geochemical characteristics and source of natural gases in the northern Jizhong Subbasin, Bohai Bay Basin, eastern China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3789, https://doi.org/10.5194/egusphere-egu2020-3789, 2020.

Research on hydraulic fracture initiation and vertical propagation

behavior in laminated tight formation

Anan Wu1, Bing Hou*1, Fei Gao2,Yifan Dai1,Mian Chen1

  • (1. State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum-Beijing, Beijing, China No.1 Cementing Company, Bohai Drilling Engineering Company Limited, CNPC, China. Renqiu,062550)

 

Abstract: The extent of hydraulic fracture vertical propagation extent is important in evaluating simulated reservoir volume for laminated tight reservoirs. Given that it is affected by the discontinuities (beddings, natural fractures, and other factors), fracture geometry is complex in the vertical plane and is different from a simple fracture in a homogeneous formation. Because the tight formation bedding is very developed, hydraulic fracture is difficult to spread vertically. Now,the propagation mechanism of hydraulic fracture in the vertical plane has not been well understood. To clarify this mechanism, several groups of large-scale tri-axial tests were deployed in this study to investigate the fracture initiation and vertical propagation behavior in laminated tight formation. The influences of multiple factors on fracture vertical propagation were studied.

we carried out the indoor hadraulic fracturing physical simulation experiments of the bedding-developed rocks. Tight cores obtained from the core well were wrapped with cement into 30 cm cubes, and samples were drilled and cemented. Before the experiment ,three-dimensional axial stress was applied to simulate the stratigraphic environment. When the stress was balanced, a certain flowing rate was set for hadraulic fracturing. After the fracturing work was completed, the cement block was opened to observe the hydraulic fracture propagation pattern.

The results showed that the ultimate fracture geometries could be classified into three categories: simple bedding fracture, slight turning fracture, stair-like fracture, and multilateral fishbone-like fracture network. Here comes some research knowledge:(1)When the difference between the vertical stress and the minimum horizontal principal stress is less than 12Mpa, the hydraulic fracture will only expand along the rock bedding plane Furthermore. (2)when the vertical stress difference is close to 14 MPa, hydraulic fractures will generate vertical fractures that will communicate multiple beddings of the rock. (3)Increasing flowing rate will cause a slight turning or jumping fractures and improve the complexity of fractures to a certain extent. (4)because of the influence of beddings and lithology,the fracture pressure is usually high.

Key words: Hydraulic fracturing, tight reversior Bedding plane, fracture morphology.

How to cite: wu, A.: Research on hydraulic fracture initiation and vertical propagation behavior in laminated tight formation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6427, https://doi.org/10.5194/egusphere-egu2020-6427, 2020.

EGU2020-7404 | Displays | ERE3.1

Change in reservoir structure of different lithotypes of lignite with dehydration

Fudong Xin, Hao Xu, and Dazhen Tang

Find out the changes in lignite properties accompanying dehydration will not only benefit the development of lignite CBM, but also play a guiding role in the underground gasification, combustion, coal cleaning, and carbon dioxide sequestration. Especially for the utilization of lignite coalbed methane resources, the dehydration can greatly improve the gas flow capacity in lignite reservoir with originally low permeability. Through nuclear magnetic resonance (NMR) tests, imaging experiments, and permeability tests, the changes of reservoir properties of different lithotypes of lignite during dehydration were comprehensively summarized. Additionally, a bituminous coal sample was also tested as a supplement to better understand the impact of coal rank on changes in reservoir structure after dehydration. Drying and dehydration will cause the coal matrix to shrink, and NMR results show that its effect on the structure of the lignite reservoir is shown in two aspects: the rapid expansion of large fractures, and the shrinkage of relatively small pores. Due to the influence of material composition and molecular structure, the change of the reservoir structure of bituminous coal after dehydration was not as obvious as that of lignite. Overall, dehydration improves both total porosity and connected porosity. However, due to the shrinkage of the matrix, the pore connectivity may deteriorate. As a paramagnetic material, Mn2+ dissolved in water shorten the transverse relaxation time of the 1H by dipole-dipole interaction (dipolar coupling) between the electronic magnetic moment of the ion and the nuclear magnetic moment of the hydrogen proton. As Mn2+ enters the connected pores, the signal of the water in these pores is dampened and becomes invisible. It is clear that the disappeared portion on the T2 spectrum represents the connected pores into which Mn2+ can enter. By combining the NMR experiment with Mncl2 imbibition, it was found that the connectivity of some of the micro-mesopores was worsened: the disconnected porosity of the matrix lignite and xylite lignite after 12 hours of drying increased from 0.32% and 0.08% to 1.19% and 1.82%. NMR imaging and X-ray computed tomography imaging results show different fracture propagation rules of different types of lignite during drying. Matrix lignite can quickly generate evenly distributed fractures with drying, but these fractures are short in length and poor in orientation; xylite lignite has a lower dehydration efficiency, and the fractures generated follow a pattern that gradually expands from the surface to the interior, but can eventually form a long and well-oriented fracture network. The results of permeability tests show that dehydration greatly improves the permeability of lignite reservoirs. Since coal permeability is highly stress-sensitive, the effect of stress on the permeability of these samples before and after dehydration was further analyzed. Although the effect of stress on permeability after drying has increased, the effective permeability after drying is always orders of magnitude higher than before drying. In sum, dehydration is an effective measure to improve the seepage capacity of lignite reservoirs, which provides a basis for the efficient development of lignite CBM and the clean use of lignite resources in other ways.

How to cite: Xin, F., Xu, H., and Tang, D.: Change in reservoir structure of different lithotypes of lignite with dehydration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7404, https://doi.org/10.5194/egusphere-egu2020-7404, 2020.

In order to investigate the controlling of the sedimentation environment evolution on the coalbed methane system in Xishanyao Formation on the southern margin of Junggar Basin,using drilling wells,logging wells,outcrops and other data with the assistance of fine analysis methods,such as scanning electron microscope and image granularity,the coalbed methane system was divided,and its sedimentation evolution process was researched. The research results show that sand body of five types of sedimentation microfacies,whose water and air blocking capacity is sorted as “diversion channel<crevasse splay and beach dam<natural levee and shore-shallow lake”,can be identified in the research area,and single-well vertical coalbed methane system was divided; during the SQ1—SQ2 period,the rise of lake level led to the expansion of the development area of lacustrine facies,as well as the weakening of the coal-accumulating process which was mainly concentrated in the TST and LST stages of SQ1,and the east-west characteristic difference regarding the coalbed development and gas content appeared and was in accordance with the plane distribution of sedimentary facies; during exploitation,the coalbed methane system should be defined according to the blocking capability of surrounding rock,appropriate exploitation methods should be selected according to the characteristics of each system,and the avoidance of vertically joint-developing sandstone aquifer and combined layer series of development should be paid attention to.

How to cite: zhang, A. and Tang, S.: Study on the composition and inter-layer correlation of coalbed methane system of Xishanyao Formation under sedimentary control, Southern Junggar Basin, NW, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7747, https://doi.org/10.5194/egusphere-egu2020-7747, 2020.

EGU2020-10609 | Displays | ERE3.1

Hele-Shaw Cell of Varying Thickness for Modeling of Leakage Pathways

Elizabeth Trudel and Ian Frigaard

Canada is an important player in the global oil and gas industry and is ranked fourth largest producer of natural gas and crude oil. Alberta and British Columbia are the two largest producing provinces of natural gas with a combined 98% of the national production. Recent development of the Montney formation, a low permeability unit, has led to a rise in the number of unconventional (horizontal and hydraulically fractured) wells drilled in Western Canada. Recent studies have shown that 28.5% of wells drilled starting in 2010 in British Columbia have reported an instance of wellbore leakage, and 4.0% of the wells drilled in Alberta during the same time period have also reported an instance of wellbore leakage resulting in several thousand wells with known leakage issues in these two provinces. Wellbore leakage is the unwanted flow of hydrocarbons from the reservoir, or a formation intersected by the well, through leakage pathways found along the wellbore and discharging to the atmosphere through either the surface casing assembly, surface casing vent flow (SCVF) or a surrounding permeable formation, gas migration (GM). In addition to the greenhouse gas emissions produced by wellbore, groundwater contamination may occur. Provincial regulations state that the remediation of cases of non-serious wellbore leakage, which represents 85.5% of the cases of wellbore leakage in Alberta and over 94% of the cases in British Columbia, can be delayed until the time of well abandonment. Less than 30% of the gas wells in these provinces have been abandoned and both provinces are seeing an alarming number of suspended wells which can be considered ready for abandonment. At which point, wells experiencing wellbore leakage will need to be remediated. Understanding of wellbore leakage, which occurs through leakage pathways such as radial cracks and microannulus, is limited. The model presented in this study relies on flow through a Hele-Shaw cell of varying thickness representing a microannulus. Microannulus thickness data is obtained through experimental data available in the literature. The aim of the model is to determine the flow rate of natural gas through a microannulus of varying thickness and the resulting permeability of the leakage pathways.

How to cite: Trudel, E. and Frigaard, I.: Hele-Shaw Cell of Varying Thickness for Modeling of Leakage Pathways , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10609, https://doi.org/10.5194/egusphere-egu2020-10609, 2020.

EGU2020-11963 | Displays | ERE3.1 | Highlight

The Western Canada Sedimentary Basin energy wells: δ13C gas isotopic mapping, from production to ground migration

Gabriela Gonzalez Arismendi and Kalis Muehlenbachs

Despite the emerging new technology in renewables, society still relies overwhelmingly on fossil fuels for energy. Overall, data indicate that there is an increase in natural gas production as a less expensive, more “environmentally friendly” and efficient resource.  ẟ13C studies are a standard tool to understand the origin, migration and mixing of natural gases. In the Western Canada Sedimentary Basin (WCSB), which is a major hydrocarbon producer, the isotopic variability of formations gases have been well characterized (i.e., Tilley and Muehlenbachs, 2006). Industry implements such information for predicting where economically substantial amounts of natural gas form. Ethane isotopic fingerprinting is more diagnostic of such thermally matured gases. Thus, it is a useful tool to identify unwanted fugitive gas emissions associated with petroleum resource development and activities. In an initiative to better understand, constrain and ultimately mitigate this historic engineering challenge, we contoured the isotopic values of 2800 SCV wells and 1200 GM, and used the production data to identify the source of gas emissions. Our outcomes are not only valuable to industry, but also to regulatory agencies to increase awareness about the use of organic (e.g. n-alkanes) and inorganic (e.g. CO2) carbon isotope fingerprinting as retrospective environmental indicators at a local and regional scale.

Reference:

Tilley, B., and Muehlenbachs, K. (2006). Gas maturity and alteration systematics across the Western Canada Sedimentary Basin from four mud gas isotope depth profiles. Organic Geochemistry, 37(12), 1857–1868.

How to cite: Gonzalez Arismendi, G. and Muehlenbachs, K.: The Western Canada Sedimentary Basin energy wells: δ13C gas isotopic mapping, from production to ground migration , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11963, https://doi.org/10.5194/egusphere-egu2020-11963, 2020.

EGU2020-12089 | Displays | ERE3.1

Well location optimization of Zama reservoir using top down reservoir modeling(TDRM)

Taehun Lee, Kyungbook Lee, Hyunsuk Lee, and Wonsuk Lee

Artificial intelligence is applied in various fields of human life and is being actively studied and applied in the oil fields. Especially, the digital oil field, which has recently been spotlighted, is required to simulate the reservoir using artificial intelligence. However, there is almost little research to date. Therefore, in this study, we applied TDRM using artificial intelligence technology to Zama field located on the land of Canada. The required static and dynamic data were obtained from Accumap, a Canadian well information S/W. As a result, the reservoir model was constructed successfully and the well location optimization could be performed in a short time using TDRM.

How to cite: Lee, T., Lee, K., Lee, H., and Lee, W.: Well location optimization of Zama reservoir using top down reservoir modeling(TDRM), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12089, https://doi.org/10.5194/egusphere-egu2020-12089, 2020.

Compared with marine shale with plentiful research and successful exploration, fewer studies on transitional shale reservoirs limit further exploitation of shale gas. In this paper, comparative analysis, between Lower Silurian marine shale and Upper Permian transitional shale in the Upper Yangtze region, is carried out to analysis pore features of both shales and the main controlling factors, which can provide theoretical guidance for further exploration. A combination of methods is ultilized in terms of organic-chemistry geology measurement, X-ray diffraction (XRD), high-pressure mercury injection, gas adsorption, and focused ion beam milling and scanning electron microscopy (FIB-SEM). The results show that Lower Silurian marine shale and Upper Permian transitional shale have similar organic matter (OM) abundance (2.72% and 2.31%) and thermal degree (2.56wt%Ro and 2.68wt%Ro). However, the kerogen of Lower Silurian shale is type I derived from algae and plankton, while that of Upper Permian shale is mainly type III from higher plant debris. As for mineral composition, Siliceous minerals (> 43wt%) account for the majority in Lower Silurian shale, while clay (> 57wt%) is the main mineral in Upper Permian shale. Variations in material basis trigger to differences in pore characteristics between the two shales. Firstly, the pores in Lower Silurian shale are mostly hosted by OM with an average pore diameter of 7.94 nm, while Upper Permian shale mainly develops pores associated with clay minerals with an average pore diameter of 28.60nm. Moreover, Lower Silurian shale presented relatively higher pore properties than Upper Permian in both average pore volume (0.020ml/g and 0.015ml/g) and average pore surface area (7.99 m2/g and 1.2 m2/g). Various factors lead to the differences in pore types and pore properties between the two shales. For marine shale, OM with thermal convertibility tend to be mobilizable and porous. OM-hosted pores are the dominated type which is controlled by OM abandauce and thermal degree. However, in transitional shale, OM is featured by phase stability without porous feature. Pores associated with clay flakes are the main type which is controlled by the specifc material composition. Hence, the discrepancies of pore properties may be attributed to material diversities between marine shale and transitional shale.

How to cite: Jiang, H., Jiang, Z., and Li, X.: Different controlling factors of pore features between marine shale and transitional shale in the Upper Yangtze region, South China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12146, https://doi.org/10.5194/egusphere-egu2020-12146, 2020.

EGU2020-12187 | Displays | ERE3.1

Experimental Modelling of Black Carbon Emissions from Gas Flares in the Oil and Gas Sector

Parvin Mehr, Bradley M. Conrad, and Matthew R. Johnson

Flares in the upstream oil and gas (UOG) industry are an important and poorly quantified source of black carbon (BC) emissions and may be a dominant source of black carbon deposition in sensitive Arctic regions (Stohl et al. 2013).  Accurate estimation of flare BC emissions to support informed policy decisions, accurate climate modeling, and new international reporting regulations under the Gothenburg protocol is a critical challenge.  To date few studies have focussed on the primarily buoyancy-dominated turbulent non-premixed flames typical of upstream oil and gas flares, such that existing emission factor models are highly uncertain (see (McEwen and Johnson 2012)).  Although recent progress has been made in measuring black carbon from flares in the field (e.g. (Conrad and Johnson 2017; Johnson et al. 2013), data have also shown that emissions of individual flares may vary by more than 4 orders of magnitude. 

The objective of the current study is to develop a robust data-backed model to predict black carbon emissions from flares considering variations in flare gas composition, flow rates, and stack diameters.  Laboratory measurements of black carbon (soot) for a range of turbulent non-premixed jet diffusion flames of up to 3 m in length were performed at the Carleton University Flare Facility in Ottawa, Canada.  Two hundred and thirty cases spanning five flare stack diameters (25.4 to 76.2 mm), exit velocities from 0.16 to 15.15 m/s, and a broad range of industrially-relevant multicomponent (C1-C7 hydrocarbons, CO2, N2) flare gas compositions were studied.  Emissions were captured in a large (~3.1 m diameter) sampling hood and forwarded to gas- and particulate phase analyzers. 

Black carbon concentrations were measured via a Sunset Labs thermal-optical instrument using the OCECgo software tool (Conrad and Johnson 2019) to quantify uncertainties via Monte Carlo analysis.  BC yields were subsequently calculated using a mass-balance methodology (Corbin and Johnson 2014).  Variability in BC yield was well-predicted by an empirical model incorporating both the aerodynamic and chemistry effects.  For this range of conditions, it was observed that primary independent variables (such as exit velocity and higher heating value) act as reasonable surrogates for sooting propensity.  Further experiments are underway to test the proposed model over a broader range of conditions.  However, results to date represent a significant advance in our ability to predict black carbon emissions from flares.

How to cite: Mehr, P., Conrad, B. M., and Johnson, M. R.: Experimental Modelling of Black Carbon Emissions from Gas Flares in the Oil and Gas Sector, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12187, https://doi.org/10.5194/egusphere-egu2020-12187, 2020.

EGU2020-17423 | Displays | ERE3.1

Porosity and hydrocarbon composition evolution in shales from the Domanic and Bazhenov Formations: Insights from pyrolysis and aqua thermolysis experiments.

Dina Gafurova, Anton Kalmykov, Dmitriy Korost, Tikhonova Margarita, and Vidishcheva Olesia

The Domanic and Bazhenov Formations are the largest unconventional oil and gas resources in Russia. In this regard, research of mechanisms and transformation features of pore space structure, as well as hydrocarbon fluids composition are of greatest interest. In recent time technologies for modeling of thermal maturation of rocks under close to reservoir conditions similar, such as pyrolysis and aqua pyrolysis can be used. The natural process of organic matter maturation has a direct impact on the rock pore space alterations. Experimental studies of rocks (more than 100 experiments) with monitoring of the pore space using computer microtomography were performed. As a result of research, it was possible to clarify the influence of rock characteristics on the transformation of the pore space, as well as on the hydrocarbons composition. The structural features of the mineral part of the rock control the distribution of organic matter: for rocks with a layered distribution of organic matter, the formation of a crack system is characteristic. In samples with a massive structure, newly formed pores were noted. The rocks with the highest organic matter content from 20% were characterized by the formation of lenses (Fig. 1). The content of organic matter and its maturity directly affect the volume of the newly formed pore space.

Performed investigations allowed to reveal the trends of hydrocarbons generation in source rocks and unconventional reservoirs formation. Also heating of rocks by various methods under reservoir conditions approved potential of tertiary methods of reservoir stimulation. Pyrolysis in-situ of Bazhenov and Domanic source rocks would allow to generate “synthetic” oil of similar to natural one composition and increase permeability of rocks by pores and cracks formation.

This work was partially (fully) supported by RFBR grant 18-35-20036.

How to cite: Gafurova, D., Kalmykov, A., Korost, D., Margarita, T., and Olesia, V.: Porosity and hydrocarbon composition evolution in shales from the Domanic and Bazhenov Formations: Insights from pyrolysis and aqua thermolysis experiments., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17423, https://doi.org/10.5194/egusphere-egu2020-17423, 2020.

Title: Paleogeographic framework and Paleo-sedimentary environmental restoration in the Lower Part of Yanchang formation in Triassic of Ordos Basin, China

Ordos basin is a craton basin, rich in coal, oil and natural gas resources. The Yanchang formation includes the lower part (Chang 10- Chang 8 oil bearing intervals) and the upper part (Chang 7- Chang 1 oil bearing intervals) in which we found many hydrocarbon-rich depressions. The sedimentary period of Chang 10-Chang 8 formation is the transition stage from the North China Craton depression basin to  Ordos basin due to the influence of the Indosinian movement. Previous studies mainly focused on the the interior of the present residual basin rather than the peripheral of the basin.

Twenty five outcrops out of Ordos basin and one hundred drilling cores in the basin are used and multiple methods including microscope, SEM observation , the major-trace elements analysis ; zircon U-Pb geochronological studies and seismic profile interpretation are applied to study the paleoredox, paleosalinity , paleoclimate and provenance of the the lower part of the Yanchang formation in the Ordos basin.

It is concluded that: (1)the main charateristics of the sedimentary facies about Chang 10 is rivers-deltas- shore-shallow lacustrine. The sedimentary facies of Chang 9 has the features of “multi-deltas surrounding the lake” with a transitory lake transgression. The main charateristics of Chang 8 is that the rivers became more powerful and the area of lake increased.(2) based on the zircon U-Pb age structure comparision beween the lower part the Yanchang formation and its periphery old land, the results indicate that it has consistent source, which are mainly northern and southern margin of Huabei block. However, the north-east Alashan old land and south Qinlin-Qilian tectonic belts may just supply few detrital sediments.(3) according to the seismic interpretation, we have found a large number of synsedimentary fault. Seismites developed in Chang9 and Chang8 and turbidite developed in Chang9. The distribution of the synsedimentary fault, seismites and turbidite can cetify that the structure activity was more active in the sedimentary period of the Yanchang formation.

How to cite: Xu, Y. and He, D.: Paleogeographic framework and Paleo-sedimentary environmental restoration in the Lower Part of Yanchang formation in Triassic of Ordos Basin, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18048, https://doi.org/10.5194/egusphere-egu2020-18048, 2020.

EGU2020-22215 | Displays | ERE3.1

Radioactivity in the gas pipeline network in Poland

Pawel Jodlowski, Jakub Nowak, and Jan Macuda

The radiological risk in natural gas industry is mostly connected with radon (Rn-222) and its progeny: Po-218, Pb-214, Bi-214, Po-214 and Pb-210. The radon activity concentration in natural gas transported by gas pipelines varies in a wide range from dozens of Bq/m3 to several thousand Bq/m3 and mainly depends on the proximity of mines and geological structure of the deposit from which natural gas is extracted and transported. The radon progeny are ion metals, which are easily adsorbed on aerosols and deposited on the inner surfaces of gas pipe and other gas processing equipment such as scrubbers, compressors, reflux pumps, control valves and product lines creating thin radioactive films. Additionally, radon progeny together with aerosols (in contrast to radon) are retained on filters. In the aftermath of successive radioactive decay of short-lived radon progeny, long-lived Pb-210 is accumulated on filters.

             The paper presents the study of the Rn-222, Pb-210 connected with the transport of natural gas by the gas pipeline network in Poland. In the scope of the study the measurements of activity concentration of radon (Rn-222) in the gas samples (with alpha scintillation cells), radiolead Pb-210 in spent filter cartridges and dust samples collected from the gas pipeline network (with gamma-ray spectrometry) were performed.

             The results show that the Rn-222 activity concentration in natural gas varies from the detection limit of the applied method (30 Bq/m3) to around 1400 Bq/m3. Generally, the Rn-222 concentration in natural gas samples fluctuate around the mean radon concentration in the air of dwellings in Poland. The elevated radon activity concentrations in natural gas of several hundreds of Bq/m3 and more are observed at locations where the gas directly comes from local gas mines or where there is a blend of the national gas with imported one. Relatively low radon concentration in imported natural gas is connected with the fact that this gas was imported from abroad. Therefore, the time elapsed from the gas extraction to the collection of samples was relatively long. In consequence, the concentration of Rn-222 in the gas significantly decreased due to radon decay (3.4 days). Additionally, the temporal variability (daily and weekly) of the radon activity concentration in the natural gas were assessed. The results show radon concentrations does not statistically change in daily or weekly time scale.

             The Pb-210 activity concentration in dust ("black-powder") from gas filters and spent filter cartridges is high and varies from 500 to 17000 Bq/kg and from 200 to 2900 Bq/kg respectively.

How to cite: Jodlowski, P., Nowak, J., and Macuda, J.: Radioactivity in the gas pipeline network in Poland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22215, https://doi.org/10.5194/egusphere-egu2020-22215, 2020.

EGU2020-22560 | Displays | ERE3.1

Evaluation of the subject geological area suitability for oil recovery by High-Pressure Air Injection method

Askarova Aysylu, Cheremisin Alexander, Solovyev Aleksei, and Cheremisin Alexey

The considerable decline of conventional oil and gas reserves and respectively their production introduces new challenges to the energy industry. It resulted in the involvement of hard-to-recover reserves using advanced enhanced oil recovery (EOR) techniques. Thermal methods of EOR are recognized as most technically and commercially developed methods for the highly viscous crude. High-Pressure Air Injection (HPAI) is one of the thermal production methods that reduce oil viscosity and increases the recovery (Yoshioka et al, Moore et al., 2002). HPAI has been already effectively applied for different types of reservoirs development and proven to be economically feasible. 

The application performance of the HPAI technology strongly depends on the quality of experimental and numerical modeling conducted on the the target object basis. Prior to the field tests physicochemical and thermodynamic characteristics of the process were studied. Further consequent numerical modeling of laboratory-scale oxidation experiments and field-scale simulation were conducted to estimate HPAI method feasibility based on the results of oxidation studies. A medium pressure combustion tube (MPCT) oxidation experiment was carried out to provide stoichiometry of the reactions and field design parameters. A 3D numerical model of the MPCT experiment was constructed taking into account the multilayer design, thermal properties, heating regimes and reaction model (Sequera et al., 2010; Chen et al., 2014; Yang et al., 2016). The “history” matched parameters such as fluid production masses and volumes, temperature profiles along the tubes at different times and produced gas composition demonstrated good correspondence with experimental results. The results obtained during the experiment and modeling of MPCT (fluid properties, relative phase permeability, kinetic model, technological parameters) were used in field-scale modeling using various thermal EOR scenarios. Air breakthrough into production wells was observed, thus a 2 percent oxygen concentration limit where implied. The overall performance of four different scenarios was compared within 15 years timeframe. The development system was also examined to achieve the maximum economic indicators with the identifications of risks and main uncertainties.

 

How to cite: Aysylu, A., Alexander, C., Aleksei, S., and Alexey, C.: Evaluation of the subject geological area suitability for oil recovery by High-Pressure Air Injection method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22560, https://doi.org/10.5194/egusphere-egu2020-22560, 2020.

ERE4.1 – Versatile subsurface storage for future energy systems

EGU2020-13889 | Displays | ERE4.1

Aquifer-CO2 Leak project: Physicochemical characterization of the CO2 leakage impact on a carbonate shallow freshwater aquifer

Anélia Petit, Adrian Cerepi, Corinne Loisy, Olivier Le Roux, Léna Rossi, Pierre Chiquet, Audrey Estublier, Julien Gance, Bruno Garcia, Lisa Gauchet, Benoit Hautefeuille, Bernard Lavielle, Laura Luu Van Lang, Sonia Noirez, Benoit Texier, Pierre Bachaud, and Sarah Bouquet

This work is part of the Aquifer CO2-Leak project, started in 2018 for a 4-years duration and that aims at evaluating the impact of CO2 leakages from a geological storage site and developing new monitoring tools and methodologies. The present study aims to understand, quantify and model the environmental impact of a CO2 leak on water quality in the carbonate freshwater aquifer and understanding CO2-water-carbonate interactions.

This research has been performed on an experimental site located in Saint-Emilion (Gironde, France), in an underground quarry within a 30-meter-thick carbonate formation dated to the Upper Oligocene. The facies vary from wackestone to grainstone, and are associated with high values of porosity (from 25 to 45%) and permeability (between 5 and 20 D). A gas mixture, composed of CO2 (90%), He (9%) and Kr (1%), was injected in the aquifer through a borehole located upstream hydraulic gradient. The total injected volume was 200 liters for 1h30.

The seven other boreholes downstream in the injection well were fitted with in-situ probes which automatically measured pH, electrical conductivity, and CO2 fraction. Periodic water samplings have been undertaken, to determine the elementary concentrations by ionic chromatography. The spread of dissolved CO2 in the freshwater aquifer has influenced the physicochemical parameters at the various measurement points and thus has been followed in the time.

The interaction between the CO2 and the limestones causes the dissolution of the calcite, releasing Ca2+ and CO32- in the solution, which are distributed between H2CO3, HCO3- and CO32-. The comparison of the results before and after the passage of the plume highlights a dissolved CO2 concentration increase, combined with an increase of electrical conductivity and temperature, as well as a decrease in pH values.

The evolution of the physicogeochemical signature in the aquifer allow to understand the reactive and transport processes during a migration of a CO2 plume in a leakage context. The acquisition of these results will make possible to model a leakage in a complex natural reservoir.  Electrical conductivity and pH measurements seem to be excellent indicators for monitoring a gas plume during CO2 geological storage. The laboratory analyzes lead to better understand the CO2-water-carbonate interactions produced at the field scale and the relationships with petrophysical properties.

Batch measurements study the evolution of the electrical conductivity, monitored as a function of the COconcentrations. Comparison of experiments using only water, water and sand or water and limestone, have shown that only the presence of carbonate ions allows an increase in this geophysical parameter.

 

By means of these different tools and measures, the propagation of a CO2 leak will be followed through the modification of physicochemical parameters in the aquifer. This should also change the electrical resistivity values across the unsaturated zone. The electrical resistivity tomography should be a complementary tool in order to support these results, and to represent a 3D image plus time of the CO2 plume.

How to cite: Petit, A., Cerepi, A., Loisy, C., Le Roux, O., Rossi, L., Chiquet, P., Estublier, A., Gance, J., Garcia, B., Gauchet, L., Hautefeuille, B., Lavielle, B., Luu Van Lang, L., Noirez, S., Texier, B., Bachaud, P., and Bouquet, S.: Aquifer-CO2 Leak project: Physicochemical characterization of the CO2 leakage impact on a carbonate shallow freshwater aquifer, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13889, https://doi.org/10.5194/egusphere-egu2020-13889, 2020.

EGU2020-20863 | Displays | ERE4.1

CO2 Capture and Storage from Flue Gas Using Novel Gas Hydrate-Based Technologies and Their Associated Impacts

Aliakbar Hassanpouryouzband, Katriona Edlmann, Jinhai Yang, Bahman Tohidi, and Evgeny Chuvilin

Power plants emit large amounts of carbon dioxide into the atmosphere primarily through the combustion of fossil fuels, leading to accumulation of increased greenhouse gases in the earth’s atmosphere. Global climate changing has led to increasing global mean temperatures, particularly over the poles, which threatens to melt gas hydrate reservoirs, releasing previously trapped methane and exacerbating the situation.  Here we used gas hydrate-based technologies to develop techniques for capturing and storing CO2 present in power plant flue gas as stable hydrates, where CO2 replaces methane within the hydrate structure. First, we experimentally measured the thermodynamic properties of various flue gases, followed by modelling and tuning the equations of state. Second, we undertook proof of concept investigations of the injection of CO2 flue gas into methane gas hydrate reservoirs as an option for economically sustainable production of natural gas as well as carbon capture and storage. The optimum injection conditions were found and reaction kinetics was investigated experimentally under realistic conditions. Third, the kinetics of flue gas hydrate formation for both the geological storage of CO2 and the secondary sealing of CH4/CO2 release in one simple process was investigated, followed by a comprehensive investigation of hydrate formation kinetics using a highly accurate in house developed experimental apparatus, which included an assessment of the gas leakage risks associated with above processes.  Finally, the impact of the proposed methods on permeability and mechanical strength of the geological formations was investigated.

How to cite: Hassanpouryouzband, A., Edlmann, K., Yang, J., Tohidi, B., and Chuvilin, E.: CO2 Capture and Storage from Flue Gas Using Novel Gas Hydrate-Based Technologies and Their Associated Impacts, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20863, https://doi.org/10.5194/egusphere-egu2020-20863, 2020.

EGU2020-8912 | Displays | ERE4.1

Quantitative CO2 monitoring workflow

Bastien Dupuy, Anouar Romdhane, and Peder Eliasson

CO2 storage operators are required to monitor storage safety during injection with a long-term perspective (Ringrose and Meckel, 2019), implying that efficient measurement, monitoring and verification (MMV) plans are of critical importance for the viability of such projects. MMV plans usually include containment, conformance and contingency monitoring. Conformance monitoring is carried out to verify that observations from monitoring data are consistent with predictions from prior reservoir modelling within a given uncertainty range. Quantitative estimates of relevant reservoir parameters (e.g. pore pressure and fluid saturations) are usually derived from geophysical monitoring data (e.g. seismic, electromagnetic and/or gravity data) and potential prior knowledge of the storage reservoir.

In this work, we describe and apply a two-step strategy combining geophysical and rock physics inversions for quantitative CO2 monitoring. Bayesian formulations are used to propagate and account for uncertainties in both steps (Dupuy et al., 2017). We apply our workflow to data from the Sleipner CO2 storage project, located offshore Norway. At Sleipner, the CO2 has been injected at approx. 1000 m deep, in the high porosity, high permeability Utsira aquifer sandstone since 1996 with an approximate rate of 1 million tonnes per year. We combine seismic full waveform inversion and rock physics inversion to show that 2D spatial distribution of CO2 saturation can be obtained. Appropriate and calibrated rock physics models need to take into account the way fluid phases are mixed together (uniform to patchy mixing) and the trade-off effects between pore pressure and fluid saturation. For the Sleipner case, we show that the pore pressure build-up can be neglected and that the derived CO2 saturation distributions mainly depend on P-wave velocities and on the rock physics model. The CO2 saturation is larger at the top of the reservoir and the mixing tends to be more uniform. These mixing properties are, however, one of the main uncertainties in the inversion. We discuss the added value of a joint rock physics inversion approach, where multi-physics (electromagnetic, seismic, gravimetry), and multi-parameter inversion can be used to reduce the under-determination of the inverse problem and to better discriminate pressure, saturation, and fluid mixing effects.

Acknowledgements:

This publication has been produced with support from the NCCS Centre, performed under the Norwegian research program Centres for Environment-friendly Energy Research (FME). The authors acknowledge the following partners for their contributions: Aker Solutions, Ansaldo Energia, CoorsTek Membrane Sciences, Emgs, Equinor, Gassco, Krohne, Larvik Shipping, Lundin, Norcem, Norwegian Oil and Gas, Quad Geometrics, Total, Vår Energi, and the Research Council of Norway (257579/E20).

References:

Dupuy, B., Romdhane, A., Eliasson, P., Querendez, E., Yan, H., Torres, V. A., and Ghaderi, A. (2017). Quantitative seismic characterization of CO2 at the Sleipner storage site, North Sea. Interpretation, 5(4):SS23–SS42.

Ringrose, P. S. and Meckel, T. A. (2019). Maturing global CO2 storage resources on offshore continental margins to achieve 2DS emissions reductions. Scientific Reports, 9(1):1–10.

How to cite: Dupuy, B., Romdhane, A., and Eliasson, P.: Quantitative CO2 monitoring workflow, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8912, https://doi.org/10.5194/egusphere-egu2020-8912, 2020.

EGU2020-13028 | Displays | ERE4.1

Effects of Dip-angle on the CO2-Enhanced Water Recovery Efficiency and Reservoir Pressure Control Strategies

Zhijie Yang, Zhenxue Dai, Tianfu Xu, Fugang Wang, and Sida Jia

CO2 geological storage (CGS) proved to be an enormously significant mid-to-long-term solution for mitigating and even nullifying the net greenhouse gas emissions, and CO2-enhanced water recovery (CO2-EWR) technology may improve the efficiency of CO2 injection and saline water production with potential economic value as a means of storing CO2 and supplying cooling water to power plants. The strata with dip-angle are common in nature, because of the effects of geological structure and diagenesis. It is of great significance to study the influence of the dip-angle on the efficiency and safety of CO2-EWR. Based upon the typical formation parameters of the China Geological Survey CO2-EWR test site in the eastern Junggar Basin, a series of three-dimensional (3D) injection-extraction models with fully coupled wellbores and reservoirs were established to evaluate the effect of dip-angle on the enhanced efficiency of CO2 storage and saline production, considering geochemical reactions. Numerical simulation results show that the dip-angle has a regular influence on the formation pressure field, the CO2 transport distance in the reservoir and the CO2 sealing capacity, and the influence of dip-angle strata on the total storage amount of CO2 changed in a non-monotone mode compared with the CO2 geological storage in horizontal strata at the same injection condition. The effect of water chemical characteristics on the migration of CO2 in different phases and the transformations of major sequestered carbon minerals were determined from the resulting mechanism. Because non-horizontal strata are predominant in deep saline aquifers in nature, regardless of the influence of formation dip, CO2 leakage risks in geological storage will be greatly underestimated, and the stratum dip angle must be considered in research related to CO2 geological storage. Overall, the results of analysis provide a guide and reference for the CO2-EWR site selection.

How to cite: Yang, Z., Dai, Z., Xu, T., Wang, F., and Jia, S.: Effects of Dip-angle on the CO2-Enhanced Water Recovery Efficiency and Reservoir Pressure Control Strategies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13028, https://doi.org/10.5194/egusphere-egu2020-13028, 2020.

EGU2020-20085 | Displays | ERE4.1

Potential CO2 Networks for Carbon Storage in a German Net-Zero Emission Landscape

Christopher Yeates, Cornelia Schmidt-Hattenberger, and David Bruhn

In accordance with the European Union target of 80-95% reduction in net greenhouse gas emissions for the year 2050 relative to 1990 levels, as well as the 2050 German directive for Net-Zero greenhouse gas emissions, the Helmholtz Inititive for Climate Adaptation and Mitigation aims to provide the innovation and decision-making guidance required to both minimize future emissions and improve societal resilience to the negative consequences of anthropogenic climate change.

While the rapid development of clean energy generation infrastructure, associated with cross-sector energy efficiency improvements and progress of low-carbon technologies such as electric vehicles represent tangible contributions to this goal, a large degree of emissions remain tied to industrial processes at the core of German economic output, notably within refineries, the iron and steel industry and the cement and lime industry.

In parallel to searching for low-carbon process alternatives, or utilisation scenarios for tough-to-decarbonise emissions, the case for underground CO2 storage remains attractive both economically and from a safety point of view [1].

The German onshore territory presents a large potential for carbon storage owing to a number of stratigraphic layers presenting favourable storage characteristics (depth, thickness, porosity, as well as surrounding rock properties) with considerable geographical extent.

A significant aspect in establishing cost-effective carbon networks that are engaging for both the public and industrial partners is the creation of advantageous organisational structures that take into account viable placement of storage sites, minimal-cost pipeline networks, coherent regional grouping, sensitivity to public concerns, as well as awareness of future emission landscapes.

As a consequence, we propose a national-scale study in which we address the aforementioned constraints to create hypothetical CO2 networks based on varying regional clustering methods, number of storage sites, pipeline scalability costs and underground storage and transport constraints relating to public acceptance.

We make use of recently published graph-optimisation algorithms to ensure we achieve close-to-optimal network structures for each input CO2 sources and storage sites, and usable land space for transport [2].

The geological data used is based on literature work establishing potential CO2 storage sites, as well as a catalogue of faults of which the fault-zone conductivity is not necessarily known [3]. CO2 emission data is taken from the EU carbon trading emitters register and future emission scenarios exclude fossil energy generation.

Our results show that a large diversity of CO2 networks can be envisioned for a 2050 German Net-Zero landscape while still maintaining acceptable regional exclusivity, owing primarily to the large degree of underground storage potential available. One aspect that is not considered is the prospect of trans-national CO2 networks that could benefit both locally certain large isolated point sources close to country borders or more globally through infrastructure economy of scale.

 

[1] Global Status of CCS: 2019, Global CCS Institute

[2] Heijnen, P., Chappin, E., Herder, P. (2019): A method for designing minimum‐cost multisource multisink network layouts. - Systems Engineering, Volume 23, Issue 1, Pages 14-35

[3] Schulz, R., Suchi, E., Öhlschläger, D., Dittmann, J., Knopf, S. & Müller, C. (2013): Geothermie-Atlas zur Darstellung möglicher Nutzungskonkurrenzen zwischen CCS und Tiefer Geothermie. – Endbericht, LIAG-Bericht

How to cite: Yeates, C., Schmidt-Hattenberger, C., and Bruhn, D.: Potential CO2 Networks for Carbon Storage in a German Net-Zero Emission Landscape, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20085, https://doi.org/10.5194/egusphere-egu2020-20085, 2020.

EGU2020-19243 | Displays | ERE4.1

Fault hydromechanical characterization and CO2-saturated water injection at the CS-D experiment (Mont Terri Rock Laboratory)

Quinn C. Wenning, Antonio P. Rinaldi, Alba Zappone, Melchior Grab, Clement Roques, Ulrich W. Webber, Madalina Jaggi, Stefano M. Bernasconi, Yves Guglielmi, Matthias Brennwald, Rolf Kipfer, Claudio Madonna, Anne Obermann, Christophe Nussbaum, and Stefan Wiemer

Understanding potential caprock failure through fault zone leakage is crucial for the safe, long-term containment of a CO2 storage site. Thus, the presence of faults in caprocks will greatly affect the site characterization process in terms of the safety assessment. The CS-D experiment at the Mont Terri Lab aims at investigating caprock integrity by determining CO2-rich water mobility in a fault zone. Seven boreholes were drilled in the clay rock, all crosscutting a fault at depths of 17-30 m below the niche floor. The boreholes were fully cored, and the samples analysed in various laboratories. All boreholes were instrumented for monitoring geochemical and geomechanical changes induced by fluid injection for prolonged time, with the goal to better understand mechanisms of CO2 leakage in a faulted caprock. We deployed a multi component monitoring setup measuring pressure, axial and 3D deformation, seismic activity and cross-hole electrical resistivity. A borehole was fully dedicated to the monitoring of the injection front, as well as geochemical in-situ measurements and fluid sampling. A portable mass spectrometer for direct measurements of gas has been installed in a dedicated borehole interval. Injection and monitoring activities started in December 2018, with multiple injection tests with saline water at pressures up to 6 MPa, in order to characterize the hydraulic response of the fault. A prolonged injection of CO2-saturated water at constant head pressure started in June 2019 and lasted for about 8 months. In this contribution, we will present the analysis of the data collected during the fault characterization (hydraulic, geophysics, and core analysis) as well as results of the continuous months-long injection. Preliminary interpretation of the monitoring data suggests that a fault does not necessarily form a pathway for the fluid to escape at shallow depth.

How to cite: Wenning, Q. C., Rinaldi, A. P., Zappone, A., Grab, M., Roques, C., Webber, U. W., Jaggi, M., Bernasconi, S. M., Guglielmi, Y., Brennwald, M., Kipfer, R., Madonna, C., Obermann, A., Nussbaum, C., and Wiemer, S.: Fault hydromechanical characterization and CO2-saturated water injection at the CS-D experiment (Mont Terri Rock Laboratory), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19243, https://doi.org/10.5194/egusphere-egu2020-19243, 2020.

Natural gas (methane) has rapidly become a critically important component to the energy economies of the United States and other countries. Because storage capacity in the above-ground pipeline network is insufficient to meet demand, natural gas is stored in large underground (UGS) facilities both in the US and, to an increasing extent, throughout the world. Defining a baseline for the frequency of reported and documented off-normal occurrences, including human error, process safety, mechanical or operational issues, or natural events with or without leakage, at UGS facilities is critical to maintaining safe operation and to the development of appropriate risk management plans and regulatory approaches.

We have analyzed the frequency of off-normal occurrences at US UGS facilities hosted by each US state. Some 31 states host UGS facilities in porous rock (depleted oil-and-gas field and aquifer), and/or solution-mined salt cavern storage facilities. Data are based upon extensive searches of information available in the public domain and not all occurrences involve the stored gas or its release but which, in combination with other factors, could lead to significant problems. The number of reported occurrences, normalized by the number of facilities and the years of active operation, define the mean occurrence frequency per facility-year for each state. Bayesian probabilistic analysis then characterizes the historical occurrence frequencies and uncertainties, parsed by storage facility type, above-ground or below-ground causes, and severity of occurrence.

Both UGS facility-years and nuisance-level occurrences for depleted field storages are highly variable from state to state, for both above-ground and below-ground causes. Aquifer storage facilities show large numbers of occurrences relative to the number of facility-years, with above-ground occurrences identified for four states and a smaller number of below-ground occurrences found for a larger number of states. Salt-cavern storage has a large number of occurrences over a relatively small number of facility-years: most of which are associated with below-ground causes.

Nuisance-level occurrence frequencies for porous-rock storage facilities and for both above-ground and below-ground causes, are generally in the range of 10–1 to 10–3 occurrences per facility-year except for those in California, which exceed 10–1 occurrences per facility-year. Serious or catastrophic occurrence frequencies for depleted field storage facilities decrease to less than about 10–2 occurrences per facility-year for most states. Nuisance-level occurrence frequencies for salt-cavern storage facilities exceed 10–2 occurrences per facility-year for below-ground causes, whilst serious or catastrophic occurrences decrease to about 10–3 to 10–1 occurrences per facility-year.

How to cite: Schultz, R. and Evans, D.: State-by-state comparison of off-normal occurrence frequencies for US underground natural gas storage facilities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1387, https://doi.org/10.5194/egusphere-egu2020-1387, 2020.

EGU2020-10475 | Displays | ERE4.1

Seasonal storage of hydrogen in porous formations

Katriona Edlmann, Niklas Heinemann, Leslie Mabon, Julien Mouli-Castillo, Ali Hassanpouryouzband, Ian Butler, Eike Thaysen, Mark Wilkinson, and Stuart Haszeldine

To meet global commitments to reach net-zero carbon emissions by 2050, the energy mix must reduce emissions from fossil fuels and transition to low carbon energy sources.  Hydrogen can support this transition by replacing natural gas for heat and power generation, decarbonising transport, and facilitating increased renewable energy by acting as an energy store to balance supply and demand. For the deployment at scale of green hydrogen (produced from renewables) and blue hydrogen (produced from steam reformation of methane) storage at different scales will be required, depending on the supply and demand scenarios. Production of blue hydrogen generates CO2 as a by-product and requires carbon capture and storage (CCS) for carbon emission mitigation.  Near-future blue hydrogen production projects, such as the Acorn project located in Scotland, could require hydrogen storage alongside large-scale CO2 storage. Green hydrogen storage projects, such as renewable energy storage in rural areas e.g. Orkney in Scotland, will require smaller and more flexible low investment hydrogen storage sites. Our research shows that the required capacity can exist as engineered geological storage reservoirs onshore and offshore UK. We will give an overview of the hydrogen capacity required for the energy transition and assess the associated scales of storage required, where geological storage in porous media will compete with salt cavern storage as well as surface storage such as line packing or tanks.

We will discuss the key aspects and results of subsurface hydrogen storage in porous rocks including the potential reactivity of the brine / hydrogen / rock system along with the efficiency of multiple cycles of hydrogen injection and withdrawal through cushion gasses in porous rocks. We will also discuss societal views on hydrogen storage, exploring how geological hydrogen storage is positioned within the wider context of how hydrogen is produced, and what the place of hydrogen is in a low-carbon society. Based on what some of the key opinion-shapers are saying already, the key considerations for public and stakeholder opinion are less likely to be around risk perception and safety of hydrogen, but focussed on questions like ‘who benefits?’ ‘why do we need hydrogen in a low-carbon society?’ and ‘how can we do this in the public interest and not for the profits of private companies?’

We conclude that underground hydrogen storage in porous rocks can be an essential contributor to the low carbon energy transition.

How to cite: Edlmann, K., Heinemann, N., Mabon, L., Mouli-Castillo, J., Hassanpouryouzband, A., Butler, I., Thaysen, E., Wilkinson, M., and Haszeldine, S.: Seasonal storage of hydrogen in porous formations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10475, https://doi.org/10.5194/egusphere-egu2020-10475, 2020.

EGU2020-17949 | Displays | ERE4.1

Development of monitoring tools in soil and aquifer for underground H2 storages and assessment of environmental impacts through an in-situ leakage simulation

Elodie Lacroix, Stéphane Lafortune, Philippe De Donato, Philippe Gombert, Zbigniew Pokryszka, Francis Adélise, Marie-Camille Caumon, Odile Barrès, and Sanka Rupasinghe

 

Storing dihydrogen (H2) underground in salt caverns is seen as a vector of the energy transition. To ensure that risks related to leakage are managed, monitoring methods are needed to detect any H2 unintended migration. Because the shallow subsurface will act as an ultimate barrier before the gas reaches surface and dwellings, there is also a need to increase knowledge on geochemical impacts of a H2 leakage on shallow environments.

Geochemical monitoring methods exist and make it possible to detect H2 directly (H2 concentrations in dissolved and gaseous phases) or indirectly (e.g. CO2, O2, N2 concentrations in dissolved and gaseous phases, ionic balance and some trace elements, redox potential).

Within the framework of the Rostock'H project funded by the French R&D program GEODENERGIES, a leakage in the shallow subsurface was simulated by injecting water with dissolved H2 into the aquifer (~20 m deep). Injection was done in November 2019 on a dedicated experimental site and aimed at testing monitoring techniques but also at studying geochemical impacts at very shallow depths. The site is located in the Paris sedimentary basin (Catenoy city). The unconfined aquifer is within the Senonian (Cretaceous) chalk formation. The overlying unsaturated zone includes Bracheux sands (Paleogene) and Quaternary colluvium. The average water table is 12 m deep. The underground water has calcium-bicarbonate facies and a pH close to neutral. Eight piezometers were drilled, aligned over 80 m in the direction of the aquifer main flow (West-East) and slotted between 12 and 25 m deep. Moreover, four dry boreholes were drilled above the piezometric level to monitor the unsaturated zone. Each one was in the close vicinity of a piezometer and slotted between 3 and 11 m deep. The site was equipped with geochemical monitoring tools selected or developed by Ineris and University of Lorraine. For instance, one of the monitoring wells was equipped with a gas completion and connected to a gas RAMAN probe and to a MID IR gas cell with low optical path.

For the experiment purpose, 5 m3 of underground water were pumped, saturated with H2 at surface conditions and injected again in the aquifer using one of the piezometers. The H2 injection was preceded by an injection of 1 m3 of underground water saturated with selected chemically inert gas tracer (helium: He) and containing two selected hydrological tracers (uranine and lithium chloride) to anticipate the H2 arrival in the downstream piezometers used as monitoring wells. Dissolved gas concentrations (He, H2, N2, O2, CO2, H2S and CH4) were very frequently monitored in situ in the first 4 downstream piezometers (until 20 m from the input well) during the first week. Consequently, the maximum concentrations of dissolved He and H2 were respectively detected 49 hours and 71 hours after the injection started in the piezometer located 10 m downstream the injection well. Moreover, water samples were collected at several time steps to analyze, in laboratory, ionic balance and trace element concentrations in order to assess the environmental impact of a H2 leakage.

How to cite: Lacroix, E., Lafortune, S., De Donato, P., Gombert, P., Pokryszka, Z., Adélise, F., Caumon, M.-C., Barrès, O., and Rupasinghe, S.: Development of monitoring tools in soil and aquifer for underground H2 storages and assessment of environmental impacts through an in-situ leakage simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17949, https://doi.org/10.5194/egusphere-egu2020-17949, 2020.

EGU2020-20723 | Displays | ERE4.1

Utilization of abandoned hydrocarbon reservoirs for deep geothermal heat storage

Kai Stricker, Jens Grimmer, Joerg Meixner, Ali Dashti, Robert Egert, Maziar Gholamikorzani, Katharina Schaetzler, Eva Schill, and Thomas Kohl

Energy transition involves an increasing demand for renewable energies. Room heating and hot water account for the majority of the energy demand of private households. Thus, seasonal storage of excess heat produced during the summertime and extracted during the wintertime is of paramount importance. High temperature heat storage in the subsurface may be realized in abandoned hydrocarbon reservoirs worldwide as these reservoirs have already been extensively characterized concerning their geology, geo- and petrophysical properties as well as their depths and geometries. Although these hydrocarbon reservoirs are relatively well characterized, their potential use for geothermal heat storage has not yet been investigated. Here we focus in a first approach on abandoned oilfields of the Upper Rhine Graben (URG) in SW Germany with the aim to assess their potentials for geothermal heat storage. While geothermal production commonly targets fractured reservoirs to obtain economically viable flowrates, geothermal heat storage will aim at reservoirs with high porosities. As the productivity of hydrocarbon reservoirs is commonly controlled by their porosities, they appear as viable targets for high temperature heat storage.

We have characterized 20 abandoned hydrocarbon reservoirs in the URG, which were productive for more than five years, in Cenozoic sandstones in depths of approximately 200 – 1800 m. Our characterization is based on published data of their production histories, reservoir geology, and petrophysical properties. Most reservoirs in the URG are stacked reservoirs with inflow of hydrocarbons into the borehole from multiple stratigraphic units, as for example in Landau and Leopoldshafen, biasing an assignment of respective reservoir productivity. For heat storage injection pressure needs to be well controlled to avoid undesired hydraulic fracturing. Therefore, (theoretically) infinite reservoirs with high transmissivities appear to be more attractive and less risky than confined reservoirs.

The production histories of the various hydrocarbon reservoirs show typical patterns with a rapid increase of the annual production, followed by a slower decrease of production (tailing) before hydrocarbon production was shut down. Most reservoirs in Cenozoic sandstones show porosities of 10 to 20% with some extreme values of up to 30%. Associated permeabilities vary from 0.1 to 100 mD with some extreme values of up to 1000 mD. Data show a non-linear relationship between porosity and permeability. During hydrocarbon production water-oil ratios increase until unalluring water-oil were produced. We evaluate the potential of abandoned hydrocarbon reservoirs in the URG for heat storage by developing generic numerical models to constrain limiting conditions. The uncertainties of input parameters and their impact on heat storage potential will be addressed by a sensitivity analysis. Potential reservoirs for heat storage may be defined based on energy recovered over invested energy (EROI). Preliminary results of our numerical models show a strong dependency of the storage potential on increasing flowrates as well as on decreasing thermal conductivities of the reservoir and especially the confining layers below and above.

How to cite: Stricker, K., Grimmer, J., Meixner, J., Dashti, A., Egert, R., Gholamikorzani, M., Schaetzler, K., Schill, E., and Kohl, T.: Utilization of abandoned hydrocarbon reservoirs for deep geothermal heat storage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20723, https://doi.org/10.5194/egusphere-egu2020-20723, 2020.

EGU2020-13678 | Displays | ERE4.1

Laboratory and modelling investigations of potential geochemical reactions upon seasonal heat storage in Danish geothermal reservoirs

Hanne Dahl Holmslykke, Claus Kjøller, Rikke Weibel, and Ida Lykke Fabricius

Seasonal storage of excess heat in hot deep aquifers is one of the considered solutions to optimize the usage of commonly available energy sources. This study investigates the risk of damaging the reservoir through potential geochemical reactions induced by the increased reservoir temperature upon injection of heated formation water. Three core flooding experiments were performed at reservoir conditions and temperatures up to 150°C with cores from two potential Danish geothermal reservoirs and with synthetic brine as the flooding fluid. The tested reservoir sandstones comprise two samples with different mineralogy from the Upper Triassic – Lower Jurassic Gassum Sandstone Formation and one sample from the Lower Triassic Bunter Sandstone Formation. For the calcium carbonate-containing Bunter Sandstone formation, the experiments were performed with Ca-depleted synthetic formation water to avoid loss of injectivity by calcium carbonate scaling at elevated temperatures. The interpretation of the laboratory experiments was supported by petrographic analysis of the cores prior to and after the flooding experiments and by geochemical modelling. The results show that heating induced a series of silica dissolution/precipitation processes for all three sandstones, including dissolution of quartz, alteration of Na-rich feldspar to kaolinite, replacement of plagioclase with albite and precipitation of muscovite, depending on the sandstone. These processes are not expected to significantly deteriorate the physical properties of the reservoir. However, for the Bunter Sandstone Formation, flushed with Ca-depleted brine, a significant portion of the cementing calcite dissolved. In the reservoir, this may ultimately reduce the mechanical strength of the geological formation. Thus, this study suggests that heat storage in geothermal reservoirs can be technically feasible in typical and extensive Danish geothermal sandstone reservoirs. However, in reservoirs containing calcium carbonate, means for avoiding calcium carbonate precipitation during heat storage should be chosen with caution to minimise possible reservoir damaging side effects.

How to cite: Holmslykke, H. D., Kjøller, C., Weibel, R., and Fabricius, I. L.: Laboratory and modelling investigations of potential geochemical reactions upon seasonal heat storage in Danish geothermal reservoirs, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13678, https://doi.org/10.5194/egusphere-egu2020-13678, 2020.

EGU2020-11383 | Displays | ERE4.1

An Integrated Feasibility Study of Reservoir Thermal Energy Storage in Portland, OR, USA

John Bershaw, Erick R. Burns, Trenton T. Cladouhos, Alison E. Horst, Boz Van Houten, Peter Hulseman, Alisa Kane, Jenny H. Liu, Robert B. Perkins, Darby P. Scanlon, Ashley R. Streig, Ellen E. Svadlenak, Matt W. Uddenberg, Ray E. Wells, and Colin F. Williams

In regions with long cold overcast winters and sunny summers, Deep Direct-Use (DDU) can be coupled with Reservoir Thermal Energy Storage (RTES) technology to take advantage of pre-existing subsurface permeability and storage capacity to save summer heat for later use during cold seasons. Many aquifers worldwide are underlain by permeable regions (reservoirs) containing brackish or saline groundwater that has limited beneficial use due to poor water quality. We investigate the utility of these relatively deep, slow flowing reservoirs for RTES by conducting an integrated feasibility study in the Portland Basin, Oregon, USA, developing methods and obtaining results that can be widely applied to groundwater systems elsewhere. As a case study, we have conducted an economic and social cost-benefit analysis for the Oregon Health and Science University (OHSU), a teaching hospital that is recognized as critical infrastructure in the Portland Metropolitan Area. Our investigation covers key factors that influence feasibility including 1) the geologic framework, 2) hydrogeologic and thermal conditions, 3) capital and maintenance costs, 4) the regulatory framework, and 5) operational risks. By pairing a model of building seasonal heat demand with an integrated model of RTES resource supply, we determine that the most important factors that influence RTES efficacy in the study area are operational schedule, well spacing, the amount of summer heat stored (in our model, a function of solar array size), and longevity of the system. Generally, heat recovery efficiency increases as the reservoir and surrounding rocks warm, making RTES more economical with time. Selecting a base-case scenario, we estimate a levelized cost of heat (LCOH) to compare with other sources of heating available to OHSU and find that it is comparable to unsubsidized solar and nuclear, but more expensive than natural gas. Additional benefits of RTES include energy resiliency in the event that conventional energy supplies are disrupted (e.g., natural disaster) and a reduction in fossil fuel consumption, resulting in a smaller carbon footprint. Key risks include reservoir heterogeneity and a possible reduction in permeability through time due to scaling (mineral precipitation). Lastly, a map of thermal energy storage capacity for the Portland Basin yields a total of 87,000 GWh, suggesting tremendous potential for RTES in the Portland Metropolitan Area.

How to cite: Bershaw, J., Burns, E. R., Cladouhos, T. T., Horst, A. E., Van Houten, B., Hulseman, P., Kane, A., Liu, J. H., Perkins, R. B., Scanlon, D. P., Streig, A. R., Svadlenak, E. E., Uddenberg, M. W., Wells, R. E., and Williams, C. F.: An Integrated Feasibility Study of Reservoir Thermal Energy Storage in Portland, OR, USA, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11383, https://doi.org/10.5194/egusphere-egu2020-11383, 2020.

EGU2020-15513 | Displays | ERE4.1

The 3D stress state within typical salt structures

Tobias Baumann, Boris Kaus, Anton Popov, and Janos Urai

Salt caverns are created during the process of solution mining or built actively for underground storage purposes required for the energy transition. In most cavern-scale numerical models, deviatoric stresses within the salt dome are assumed to be negligible in magnitude. However, as salt structures are typically not homogeneous, this assumption is known to be incorrect. Stress variations may be caused by internal heterogeneities such as the presence of anhydrite layers, or by the large-scale structure and ongoing deformation of the salt dome or pillow as a result of their lower density compared to the overlying rocks. The rheology of the salt itself, a not very well constrained parameter, which varies significantly between different types of salt, may also have a significant effect.

In the scope of the Dutch KEM-17 project (Knowledge Programme on Effects of Mining) on Over-pressured salt solution mining caverns and possible leakage mechanisms, we examined which differential stresses can develop in a typical salt-structure (salt pillow, salt wall, and flat-bedded salt).  In order to make recommendations for avoiding undesired interference effects between caverns and salt dome boundaries, it is crucial to understand better how the stresses caused by salt-deformation vary within the salt dome. Which lower/upper bounds are to be expected for a particular type of structure? Where are such stresses likely to be negligible, and can we safely use existing approaches that neglect the background stress field? To what extent do uncertainties in the model parameters and geometries affect the stress state in the salt dome? To answer these questions, we used 3D thermomechanical models, for which we incorporated the state-of-the-art rheological flow laws of salt and assessed the stress state over approximately 300 kyrs, including the effect of tectonic regimes and glacial (un-)loading.

How to cite: Baumann, T., Kaus, B., Popov, A., and Urai, J.: The 3D stress state within typical salt structures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15513, https://doi.org/10.5194/egusphere-egu2020-15513, 2020.

Underground pumped storage hydropower (UPSH) is an alternative energy storage system (ESS) for flat regions, where conventional pumped storage hydropower plants cannot be constructed due to topographical limitations. UPSH plants consist in two reservoirs, the upper one is located at the surface or possibly underground (but at shallow depth) while the lower one is underground. Although the underground reservoir can be drilled, the use of abandoned mines (deep or open pit mines) as underground reservoir is a more efficient alternative that is also beneficial for local communities after the cessation of mining activities. Given that mines are rarely waterproofed, water exchanges between UPSH plants and the underground medium are expected. Water exchanges may have negative consequences for the environment, but also for the feasibility of UPSH plants. The impacts on the environment and the plant efficiency may have hydraulic (changes of the natural piezometric head distribution, effects in the hydraulic head difference between the two reservoirs, etc.) or hydrochemical nature (dissolution and/or precipitation of minerals in the aquifer and in the reservoirs, corrosion of facilities, modification of pH, etc.). At this stage, it is required a sound understanding of all the impacts produced by the water exchanges and evaluate under which circumstances they are mitigated. This assessment will allow ascertaining criteria for the selection of the best places to construct future UPSH plants.

How to cite: Pujades, E.: An overview about the interaction between the underground pumped storage hydropower (UPSH) and the saturated subsurface medium: effects of the water exchanges on the environment and the plant efficiency , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5531, https://doi.org/10.5194/egusphere-egu2020-5531, 2020.

EGU2020-440 | Displays | ERE4.1

Role of fracturing and regional tectonic structures on secondary porosity generation in a CO2 storage plant: Hontomin pilot-plant (Spain)

Adrià Ramos, José F. Mediato, Raúl Pérez-López, Miguel A. Rodríguez-Pascua, Roberto Martínez-Orío, and Paula Fernández-Canteli

The long-term managing from the geological hazard point of view of the Hontomín onshore pilot-plant for CO2 storage, located in Spain and recognized as the first and only key-test facility in Europe, is one of the main objectives stated in the ENOS European project. This project is led and funded by the European Network of Excellence on the Geological Storage of CO2 (CO2GeoNet).

The complex geological emplacement of the Hontomín Carbon capture and storage plant is considered rather relevant to analyse the impact of fracturing and both local and regional strain field on the reservoir parameters. The reservoir of Hontomín pilot-plant is formed by highly fractured Middle Jurassic dolomites with associated secondary porosity. This parameter is one of the main concerns when managing CO2 storage and monitoring.

In order to characterize the fracture pattern and its implications on a proper CO2 monitoring, we characterized the surface structural elements through the study area and their relationship with fractures affecting the reservoir porosity. The methodology followed in this work is mainly based on detailed geological mapping (field work complimented with orthophoto analysis), adding missing information from previous works. This analysis does not increase the cost for long-term monitoring, given that they are low-cost and the results are acquired in a few months.

The main structural trend in the study area, concerning faults with a wide range of displacement and metric to decametric folds, follows a regional E-W orientation. On the other hand, fractures show two main sets of trends, from NW-SE to NE-SW.

This fracturing pattern, considered as a conjugate fracture system, corresponds to the tectonic stress recorded in both Mesozoic and Cenozoic sedimentary successions where the Hontomín pilot-plant is placed. Riddle faults formed from a nearby regional right-lateral strike slip fault (Ubierna Fault) are the responsible structures for the fracture system affecting the area and the reservoir. Moreover, this fracturing pattern is in agreement with local to regional active tectonic field from Cenozoic times to present-day, when the Ubierna Fault recorded its maximum right-lateral displacement (15 km).

Secondary porosity within the reservoir can be produced from this fracture pattern, highly increasing the permeable migration paths for CO2 migration after the injection. Therefore, we state that a combination between fracture analysis and structural and tectonic study, should be considered as mandatory in the monitoring phases of the CO2 plume, during and after injection operations.

How to cite: Ramos, A., Mediato, J. F., Pérez-López, R., Rodríguez-Pascua, M. A., Martínez-Orío, R., and Fernández-Canteli, P.: Role of fracturing and regional tectonic structures on secondary porosity generation in a CO2 storage plant: Hontomin pilot-plant (Spain), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-440, https://doi.org/10.5194/egusphere-egu2020-440, 2020.

The EU H2020 GECO (Geothermal Emission Gas Control) project is aimed to produce new technologies to limit emissions from geothermal power generation by either gas re-injection or its use to produce commercial material through serpentinite carbonation. In this framework, the realization of a closed loop geothermal power plant has been planned in the Lardello geothermal area (Italy), where gas will be re-injected in a reservoir constituted by phyllites and micaschists.

A set of water-gas-rock interaction experiments was performed in order to: i) investigate the interaction between CO2-H2S gas mixture, representative of the geothermal fluids exploited at Larderello, and phyllites and micaschists of the reservoir ii) optimize the conditions for CO2 mineral sequestration by reacting CO2-H2S gas mixture with different serpentinised ultramafic rocks buried in the nearby area. During the experiments, rock powder suspended in ultrapure ion-free MilliQ® water were reacted with a gas phase (CO2-H2S=98-2% or CO2=100%) in a PARR 5500 HP stirred reactor at P-T conditions ranging from 20 to 60 bar and 90 to 250 °C, respectively. The liquid phase resulting from the experiments was analysed via ion chromatography and ICP-MS to determine ion contents, whilst rock and rock powder were examined with SEM-EDS and EPMA to identify mineral phases and determine mineral chemistry.

Preliminary results highlighted that H2S plays a pivotal role in controlling the reaction pathways with phyllites and micaschists, allowing the formation of pyrite in a wide range of P-T conditions. This process induces a selective removal of Fe from the solution, while the exceeding SiO2 deriving from mica and chlorite alteration re-precipitate as quartz. In this experiment, carbonate precipitation is prevented by the low Ca and Mg content of the samples and by the high water to rock ratio constrained by the experimental set-up. Experiments with ultramafic rocks were performed using serpentinised harzburgite and brucite-rich dunite in order to identify the most reactive lithology for mineral carbonation. Preliminary results show that CO2 sequestration is strongly enhanced by the presence of brucite compared to serpentine but further experiments are required to establish the most efficient reaction conditions.

This research is supported by European Horizon 2020 “GECO” project (Grant n° 818169).

How to cite: Bicocchi, G., Orlando, A., Ruggieri, G., Borrini, D., Rielli, A., and Boschi, C.: Towards zero emission geothermal plants in the framework of the H2020 GECO project: Insights on gas re-injection in geothermal reservoir and serpentinite carbonation from batch reactor experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-691, https://doi.org/10.5194/egusphere-egu2020-691, 2020.

EGU2020-1801 | Displays | ERE4.1

Investigation on wellbore cement degradation under geologic CO2 storage conditions by micro-CT scanning and 3D image reconstruction

Liwei Zhang, Yan Wang, Manguang Gan, Sinan Liu, and Xiaochun Li

This study presents a CT scanning and image analysis protocol to characterize wellbore cement degradation under geologic CO2 storage (GCS) conditions. The CT scanning and image analysis procedures described in the protocol are as follows: 1) CT scanning of the cement sample before exposure to CO2; 2) exposure of the cement sample to supercritical CO2 or CO2 saturated brine; 3) CT scanning of the cement sample after the exposure experiment; 4) application of 3D rigid registration to align all CT image frames, in order to eliminate pixel location variation between CT image frames due to sample drift; 5) acquisition of grayscale intensity difference images, which are obtained by subtraction of CT images after the CO2 exposure experiment from raw CT images before the CO2 exposure experiment; 6) application of noise filtering technique on grayscale intensity difference images to obtain images with good quality; 7) acquisition of 3D pore structure change of the cement sample after CO2 exposure experiment from grayscale intensity difference images, showing degradation of wellbore cement. To demonstrate the application of the protocol, an experiment of reaction between CO2 and wellbore cement under GCS conditions was conducted and the wellbore cement samples used in the experiment went through aforementioned CT scanning and image analysis procedures. CT image analysis results demonstrate a region with increased porosity in the exterior of the cement samples (Zone 1) and a region with decreased porosity next to Zone I due to CaCO3 precipitation (Zone 2). Next to Zone 2, a region with increased porosity due to Ca(OH)2 and C-S-H dissolution (Zone 3) was observed. In summary, this study proves feasibility to use 3-D CT scanning and CT image analysis techniques to investigate CO2-induced degradation of wellbore cement.

How to cite: Zhang, L., Wang, Y., Gan, M., Liu, S., and Li, X.: Investigation on wellbore cement degradation under geologic CO2 storage conditions by micro-CT scanning and 3D image reconstruction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1801, https://doi.org/10.5194/egusphere-egu2020-1801, 2020.

EGU2020-2103 | Displays | ERE4.1

Hydrogen storage in porous rocks: the storage capacity of the UK continental shelf

Jonathan Scafidi, Mark Wilkinson, Stuart Gilfillan, and Niklas Heinemann

Increasing the amount of renewable energy in the UK reduces greenhouse gas emissions but will also lead to intermittency of supply, especially on a seasonal timescale. Over-producing energy when demand is low and under producing when demand is high requires large-scale storage to redress the balance.  Hydrogen stored over seasonal timescales in subsurface porous rocks can act as a giant battery for the UK and is a flexible energy vector that can be used for heat, transport and electricity generation.

No large scale assessment of the hydrogen storage capacity of an industrialised region has yet been undertaken. Here, we present a novel method for calculating the hydrogen storage capacity of gas fields and saline aquifers on the UK continental shelf using data previously used to assess carbon-dioxide storage potential.

How to cite: Scafidi, J., Wilkinson, M., Gilfillan, S., and Heinemann, N.: Hydrogen storage in porous rocks: the storage capacity of the UK continental shelf, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2103, https://doi.org/10.5194/egusphere-egu2020-2103, 2020.

EGU2020-2584 | Displays | ERE4.1

Origin and evolution of gas in salt beds of a potash mine

Martin Zimmer and Bettina Strauch

Gases encountered in different salt beds from evacuated and packer-sealed borehole sections in a potash mine were sampled and characterized for their chemical and isotopic composition so as to conclude on their origin and evolution in the salt rocks.

These gases were either generated autochthonally or originate from fluid influx from the surrounding rocks outside the salt formation. Fixation in the salt rocks can take place laminar on mineral grain boundaries, disrupter and fracture zones or trapped in inclusions inside or between mineral grains.

In situ flow tests with pure argon between several boreholes at distances ranging from decimeter to meter suggest that formation gas is stripped from the intermediate salt packet. This gas must have been trapped on grain boundaries along the pathways of the flowing argon.

The stripped formation gas comprises mainly CO2 with traces of CH4 and H2. The CO2 isotopic composition matches well with gases originating from a mantle source, whereas CH4 is classified to be of thermogenic origin formed in a marine environment. Plausible explanations for the H2 generation are the radiolysis of water, reaction of FeII with water or microbial processes.

We conclude that these trapped gases are of allochthonous origin migrating from the surrounding rocks into the salt formation where they were fixated mainly along fracture surfaces and fissures.

How to cite: Zimmer, M. and Strauch, B.: Origin and evolution of gas in salt beds of a potash mine, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2584, https://doi.org/10.5194/egusphere-egu2020-2584, 2020.

In general, the characterization of the heterogeneity in a reservoir is considered to be important in the exploration and selection of CO2 storage formation, but it is not clear how the heterogeneity affects the evolution of the pore pressure. In particular, long-term changes in the pore pressure when most of the storage candidates are bounded by faults or bedrock, such as Korea, have been rarely examined. Many literature related to results of studies and international CCS standardization indicate that the heterogeneity of storage formation should be identified, but it is still unclear to what extent the precision or resolution of the investigation is required at the selection or design stage. The heterogeneity of sedimentary layers can be divided into two categories in terms of geographic statistics. At this time, the criteria of the classification is statistical stationarity. From a geological point of view, the statistical stationarity may be consistent with the sedimentary environment. In other words, it can be assumed that strata deposited at the same place, at similar times, and in similar circumstances have similar hydrogeological properties, despite of some detailed differences. In this case, the heterogeneity refers to “detailed differences” and the homogeneity refers to statistical parameters such as means or variances of physical properties and spatial auto-covariance. On the other hand, the nonstationary heterogeneity refers to a case where there is no statistical homogeneity, due to differences in geological structures such as faults and differences in strata such as sandstone and mudstone. In this study, the numerical sensitivity analysis was used to investigate the effect of each heterogeneity on the pressure buildup. The nonstationary heterogeneity applied in this study is a vertical structure that completely penetrates the storage formation. The results of ten models with the stationary heterogeneity showed almost similar pressure changes in the macroscale, although there were some pore pressure differences at the injection well between each of models. The pressure difference at the injection well between each model was dependent on the bulk permeability within a certain distance (200m in this study) near the injection wells, not on the average permeability of the whole system. In other words, when the injection well is installed at a point having a relatively high permeability, some additional increase in pressure due to the heterogeneity rarely occurs. However, lowering the permeability due to nonstationary heterogeneity can causes the global pressure rise in the storage formation, results were very similar to those of the case with closed boundary condition when the heterogeneity reduced the permeability to 10-4 times or less of the permeability in the storage formation.

How to cite: Kim, T.: Long-term Pressure Evolutions due to Geologic Heterogeneities during CO2 Injection, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4404, https://doi.org/10.5194/egusphere-egu2020-4404, 2020.

EGU2020-4511 | Displays | ERE4.1

Effect of Micro-MgO-based Expanding Agent on Rheological and UCS Properties of Well Cement at Early Age

Weiqing Chen, Salaheldin Mahmoud Elkatatny, Mobeen Murtaza, and Ahmed Abdulhamid Mahmoud

Well integrity issue is a major concern not only in the Oil and Gas industry but in the geo-storage field. For CO2 sequestration, in particular, poor quality cement jobs render wells to suffer from possible CO2 and formation fluid migration issues. In some cases, this migration issue maybe caused by the micro-fracture or micro-channel created during the chemical shrinkage and bulk shrinkage processes. Using some expandable cement system to cope with this issue is a promising way to mitigate this issue. In this study, we are exploring the effect of a kind of micro-MgO based expanding material on some principal properties of CO2 sequestration well cement.

In these experiments, a typical cement formulation including various additives was used. Our focus of this pilot study was to investigate the effect of expandable materials on some typical physical-mechanical properties of Portland cement with different concentrations such as 0%, 1.0%, 2.0%, 3% by weight of cement (BWOC). Meanwhile, the pure Class G Portland cement slurry was also investigated as the base experiment. By use of API standard (RP 10B) procedures, those physical-mechanical properties of the cement slurry and set cement have been studied which mainly cover such aspects as rheology, fluid-loss of the cement slurry and uniaxial compressive strength (UCS) through experimental measures.

The experimental results indicate that UCS decreases gradually with increasing concentrations of the expanding additive. The density, free fluid, and rheology of cement slurry show consistently with the variation of expanding additive concentration. In addition, the fluid loss will increase relative gradually with the increment of expansive additive concentration. By increasing the concentration of expansive additive from 0% (w/w) to 3% (w/w), cement slurry’s rheological properties consistently behaved as the main properties as plastic viscosity (PV), yield point (YP) and gel strength (GS) of 10-seconds and 10-minutes with values varied around 262.33 cP, 5.25 lb/100ft2, 6.33 lb/100ft2, and 15.26 lb/100ft2 respectively. However, the UCS value behaves contrary to the rheology properties, which gradually decreased from 63.33 MPa to 33.54 MPa with the concentration, increased from 0% to 3%. As the UCS test conducted under the curing conditions as 150 ℃, 3000psi and 24hrs, this gradual decrease of UCS maybe because of the delayed hydration characteristics of micro-MgO. Despite this decrease in USC is not positive to prevent any stressed-induced micro-channel, these results are still interesting for further corresponding study and will make the understanding of MgO based expansive additive’s effect on Portland cement matrix more completely. As per other research results and our future experimental study plan, the delayed expansion of micro-MgO hydration will compensate for the chemical and bulk shrinkage issue after enough curing.

According to the literature review, there are few publications reporting results on micro-MgO based expandable cement systems based on Class G cement.  Through this study, we are expecting to manifest a trend between the concentration of expanding additive and the cement slurry properties. This will provide the technical reference and guidance for further study and application of expanding cement systems in the industry.

How to cite: Chen, W., Mahmoud Elkatatny, S., Murtaza, M., and Abdulhamid Mahmoud, A.: Effect of Micro-MgO-based Expanding Agent on Rheological and UCS Properties of Well Cement at Early Age, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4511, https://doi.org/10.5194/egusphere-egu2020-4511, 2020.

EGU2020-6843 | Displays | ERE4.1

Seismic surveys at an artificially created field-test cavern within a salt pillar

Heike Richter, Rüdiger Giese, Axel Zirkler, and Bettina Strauch

Salt rocks serve as host rock for technical caverns due to their impermeability but their can also be influenced by fluid migration due to geological fracture zones. Seismic methods can be used to monitor cavernous structures in the transition zone between cavity and undisturbed salt rocks. Around an artificially created cavity (field-test cavern) in a salt pillar with a volume of approximately 100 litre, travel time tomography was utilized to image structures related to caverns and fluid-storage. Seismic surveys were performed at different stages of an experimental simulation of gas-water-rock interaction in the field-test cavern aiming for a better understanding of the multiphase system in the cavern-near area. The baseline survey (1) was carried out using 8 three-component piezo-electrical sensor rods and a seismic vibrator source at the surface of the salt pillar, first without an installed field-test cavern. After drilling and installing the field-test cavern, seismic cross-hole measurements were performed after producing partial vacuum in the test cavern (2) and infill of gas (3) and water (4). To finalize the field experiments the last seismic survey (5) was again conducted at the surface of the salt pillar as a repeat measurement to the baseline survey. The seismic monitoring of the salt pillar was carried out in a frequency range of 100 Hz to 14000 Hz allowing a spatial resolution in the cm-range. This was followed by pre-processing of the seismic data sets to apply the picked travel times in a tomography program. On the basis of the tomography results and reflection seismic data we want to assess the potential enlargement of the field-test cavern due to water-infill and to image the differences between unaffected salt rocks, cavernous structures and developing transition zones.

How to cite: Richter, H., Giese, R., Zirkler, A., and Strauch, B.: Seismic surveys at an artificially created field-test cavern within a salt pillar, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6843, https://doi.org/10.5194/egusphere-egu2020-6843, 2020.

EGU2020-7419 | Displays | ERE4.1

Characterization of CO2 Induced Wellbore Cement degradation by Micro CT

Yan Wang, Liwei Zhang, and Xiuxiu Miao

Wellbore cement integrity under CO2 geologic storage (CGS) conditions is a key factor to assure safe and permanent storage of CO2. Wellbore cement integrity may be impaired and the structure of cement may be altered as a result of CO2 attack. To understand how CO2-induced structure alteration in oil well cement under CGS conditions affects well integrity in CGS projects, this paper reports an experiment of reaction between CO2 and oil well cement under CGS conditions. Samples were scanned by Micro CT before and after reaction. The Micro CT is capable of operating at 140KV and 10W, has a maximum resolution of 10µm. To simulate the reaction between CO2 rich brine and oil well cement at CGS conditions, our team has developed a testing system which provides the storage temperature and pressure. 

The samples were made by standard class G oil well cement used for CGS pilot projects. The cement was cured at CO2 storage formation conditions: 62℃, 17MPa, and 1 wt% NaCl solution. The curing was maintained for 14 days. The diameter of the samples was 10 mm. Every sample contained a small borehole at center (around 1 mm diameter) that made the samples suitable for examining seepage through small leakage pathways within cement. During the reaction experiment, the samples were placed in the high-pressure, high-temperaure testing system for 14 days, given a temperature of 62℃ and a CO2 partial pressure of 17MPa. The goal of this experiment is to evaluate how the geochemical reactions between dissolved CO2 and cement affect structure of the cement. Change of borehole geometry was not observed in the Micro CT images. However, a region with decreased porosity around the borehole due to CaCO3 precipitation and a region with increased porosity around the borehole due to Ca(OH)2 and C-S-H dissolution were observable. Initial distribution of cementitious materials and solution buffering governed the width of the high-porosity region and CaCO3 precipitation region. This study demonstrates a 3-D sample characterization technique that can be used to investigate CO2-induced structure alteration of oil well cement. 

How to cite: Wang, Y., Zhang, L., and Miao, X.: Characterization of CO2 Induced Wellbore Cement degradation by Micro CT, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7419, https://doi.org/10.5194/egusphere-egu2020-7419, 2020.

EGU2020-8197 | Displays | ERE4.1

Detection of mantle CO2 in an underground salt mine via long-term and high-resolution monitoring by laser-based isotope techniques

Alexander H. Frank, Robert van Geldern, Anssi Myrttinen, Axel Zirkler, Martin Zimmer, Johannes A. C. Barth, and Bettina Strauch

Salt deposits may be affected by post-depositional CO2 intrusions. In central Germany, such CO2 contributions from the mantle may originate from Tertiary Rhön- and Vogelsberg-volcanism. The intrusion of those gases may cause technical and operational implications for storage caverns and salt mines.

Carbon isotope compositions of CO2 are useful tools to differentiate between sources and are expressed as δ13C values in ‰ versus an international standard known as the Vienna Pee Dee Belemnite (VPDB). Typical average endmember values for CO2 from the mantle are -5.1 ‰, while background air and anthropogenic influences range around averages of -11.9 ‰ and -29.8‰. Detection of fluctuations between these endmembers can be challenging with discrete sampling. This can be overcome by high-temporal resolution and long-term monitoring.

Towards this purpose, a laser-based isotope system was set up in an active underground salt mine in central Germany. For 34 days, continuous measurements of δ13C and concentrations of CO2 were generated close to a site where mantle CO2 intrusions were suspected. A timer regularly switched intakes from two capillaries, of which one was placed inside a borehole and the other in ambient air of the mine. Measured CO2 concentrations ranged between 700 and 1600 ppmV, while δ13C values ranged between -21.5 ‰ and -11.5 ‰. Lower concentrations coincided with more positive isotope values and occurred around weekends when anthropogenic influences in the mine were less.

While influences of fresh air venting may have caused these weekly shifts, the admixture of mantle CO2 seemed to play a continuous role. This is because small differences between the capillary from the borehole and the one with ambient air existed throughout the time series. Our results indicate that short-term dynamics on the order of hours to days are overlain by admixtures mantle gas intrusions of CO2.

How to cite: Frank, A. H., van Geldern, R., Myrttinen, A., Zirkler, A., Zimmer, M., Barth, J. A. C., and Strauch, B.: Detection of mantle CO2 in an underground salt mine via long-term and high-resolution monitoring by laser-based isotope techniques, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8197, https://doi.org/10.5194/egusphere-egu2020-8197, 2020.

EGU2020-9402 | Displays | ERE4.1

Electrical Resistivity Tomography Concept for CO2 Injection Monitoring at the Svelvik CO2 Field Lab

Tobias Raab, Wolfgang Weinzierl, Dennis Rippe, Bernd Wiese, and Cornelia Schmidt-Hattenberger

Carbon Capture and Storage technology is considered to be able to contribute to a carbon neutral society and is again receiving increased attention in the efforts to reduce CO2 emissions. To ensure safe operation of such CO2 storage projects, reliable monitoring technologies are required. Due to the generally high electrical resistivity contrast between CO2 and formation water, Electrical Resistivity Tomography (ERT) can be considered one of the most effective geophysical techniques in the monitoring of CO2 migration in the subsurface.

Within the ERA-NET co-funded ACT project Pre-ACT (Pressure control and conformance management for safe and efficient CO2 storage - Accelerating CCS Technologies) a CO2 injection and monitoring experiment was planned at the Svelvik CO2 Field Lab, located on the Svelvik ridge at the outlet of the Drammensfjord in Norway. The Svelvik field lab consists of four 100 m deep monitoring wells, drilled in July 2019, surrounding an existing well used for brine and CO2 injection. Each monitoring well is equipped with modern sensing systems including five types of fiber-optic cables, conventional and capillary pressure monitoring systems, as well as 16 ERT electrodes with a spacing of five meters.

With 64 installed electrodes, a large number of measurement configurations is possible. We combine the free and open-source geophysical modeling library pyGIMLI with ECLIPSE reservoir modeling to simulate the expected behavior of all cross-well electrode configurations during a CO2 injection experiment. Simulated CO2 saturations are converted to changes in apparent resistivity using Archie's law. Different considerations have to be made to select a suitable set of electrode configurations, i.e. not too large geometric factors, maximum response to the predicted change, as well as sensitivity in the target area. We select sets of configurations based on different criteria, i.e. the ratio between the measured change in resistivity in relation to the geometric factor, the maximum change in apparent resistivity, and maximum sensitivity in the target area. The individually selected measurement schedules are tested by inverting them with different assumed data errors. The numerical results show adequate resolution of the CO2 plume.

The CO2 injection took place between 27th October 2019 and 5th November 2019. Approximately two metric tonnes of CO2 were injected in 65 m depth. Preliminary field results indicate a considerably lower response than predicted by our model. These discrepancies can potentially be explained by oversimplified simulations as well as operational uncertainties. Results from baseline and repeat surveys can therefore support an integrated approach towards a revised static and dynamic model for the test site.

Acknowledgements:

This work was produced within the SINTEF-coordinated Pre-ACT project (Project No. 271497) funded by RCN (Norway), Gassnova (Norway), BEIS (UK), RVO (Netherlands), and BMWi (Germany) and co-funded by the European Commission under the Horizon 2020 programme, ACT Grant Agreement No 691712. We also acknowledge industry partners Total, Equinor, Shell, TAQA.

Finally, we thank the SINTEF-owned Svelvik CO2 Field Lab (funded by ECCSEL through RCN, with additional support from Pre-ACT and SINTEF) for assistance during installations and for financial support.

How to cite: Raab, T., Weinzierl, W., Rippe, D., Wiese, B., and Schmidt-Hattenberger, C.: Electrical Resistivity Tomography Concept for CO2 Injection Monitoring at the Svelvik CO2 Field Lab, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9402, https://doi.org/10.5194/egusphere-egu2020-9402, 2020.

EGU2020-10335 | Displays | ERE4.1

The hidden CO2 - The occurrence, distribution and composition of fluids in various salt minerals

Bettina Strauch, Martin Zimmer, and Axel Zirkler

Fluid inclusions are voids enclosed in the rock matrix and contain, depending on their origin and development, various amounts of gaseous, liquid or solid phases. Depending on their occurrence within the crystalline structure or in healed micro-fractures, primary and secondary inclusions can be distinguished. Their characteristics are utilized in various geological settings to reconstruct rock history and fluid involvement. Fluid inclusions could also be considered to be small equivalents to large cavities. As salt is regarded a favorable host rock for the storage of natural gas and other materials in artificial caverns, knowledge on gas migration and retention is crucial.

Here, we present results of a fluid inclusion study in various salt rocks using Raman spectroscopy in addition to conventional microscopic characterization and gas analysis on whole rock samples. This approach allows for a better understanding of fluid generation and migration in different salt lithologies over geological times.

Various salt minerals (halite, sylvite, kieserite and carnallite) from an area of potential overprint of CO2-dominated gas migration were investigated. Numerous fluid inclusions exhibit chevron structure and are small sized. Large single- or two-phased inclusions are observed with irregular shapes, often indicative for leakage or necking down. Interestingly, although the CO2 concentrations in whole rock samples were high, fluid inclusions were dominated by an aqueous phase and often contain numerous daughter minerals. This suggests that CO2-rich gas is stored along distinct fractures or grain boundaries within an otherwise intact rock.

How to cite: Strauch, B., Zimmer, M., and Zirkler, A.: The hidden CO2 - The occurrence, distribution and composition of fluids in various salt minerals, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10335, https://doi.org/10.5194/egusphere-egu2020-10335, 2020.

EGU2020-10725 | Displays | ERE4.1

Regional seal characterisation for CO2 storage, Northern North Sea

Christopher Lloyd, Mads Huuse, and Bonita Barrett

Estimations of CO2 storage capacities for saline aquifers, particularly the Utsira Formation (northern North Sea) have previously been calculated using a variety of numerical approaches. These are mainly based off reservoir depth maps and averaged petrophysical properties. In these first-pass estimations, a thick shale succession in the overburden is assumed to form the top seal. This is unlikely to be representative of the true, regional lithological heterogeneity and 3D variability of stratigraphic architecture, which may promote CO2 migration out of the reservoir during injection.

This study utilises a recently acquired regional high-resolution 3D broadband seismic dataset (37,500 km2) and >200 wells in the North Viking Graben, with the aim to fully characterise the overburden of the potential CO2 reservoir (Northern Utsira Formation). The objectives are to analyse: i) the presence and spatial extent of sandstone bodies in the overburden and their connectivity with the reservoir; ii) the presence of sand-filled slope channels on the clinoform foresets that may act as migration pathways; iii) evidence of previous fluid migration through the overburden. Manual seismic interpretation and well correlation is augmented by automated horizon propagation (Palaeoscan) to map individual clinoforms across the region. This is integrated with seismic attribute analysis, frequency decomposition and automated well lithology extraction to understand regional sand distribution and feature analysis (e.g. identification of channels and their fill, and possible shallow gas).

Large fan-shaped sandstone bodies (10s km-scale) are identified in the lower foresets and bottomsets of the clinothems. In the west, these are in connection with the Utsira Fm., or separated from it by a thin (<10 m) shale layer. These sands can be both beneficial to the storage capacity by producing additional gross reservoir volume (if sealed and below the critical depth for CO2), or detrimental to it if they provide a path to bypass the Utsira Fm. top seal. In the south east, sand-filled slope channels and lobes (km-scale) are recorded in the prograding clinothems but are not observed to be in connection with the Utsira Fm. (located >100 m above top Utsira Fm.). No sand-filled channels were identified in the north east from seismic attribute analysis, however the well lithology extraction for this region contained ~3% sand, thus there is a possibility of sub-seismic resolution features. In the south, foresets directly downlap the Utsira Fm. This geometry juxtaposes several individual clinothems against the reservoir, increasing the likelihood of migration if there is sand presence. This contrasts with the scenario in the north, where the bottomset of a single clinothem disconnects the reservoir from younger clinothems and restricts potential migration.

The outcome of this study is an integration of each of the regional feature maps to generate: i) a seal thickness map between the Utsira Fm. and the first overlying sand body; ii) the first leakage risk map of the Utsira Fm. that captures geological geometry and lithology distribution. These can be incorporated into any future storage estimations and identification of potential injection sites.

How to cite: Lloyd, C., Huuse, M., and Barrett, B.: Regional seal characterisation for CO2 storage, Northern North Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10725, https://doi.org/10.5194/egusphere-egu2020-10725, 2020.

EGU2020-13798 | Displays | ERE4.1

Coupled chemical osmosis and rock deformation processes in semipermeable mudstone- theoretical and experimental approaches-

Shogo Hirota, Tomochika Tokunaga, Masaatsu Aichi, Ziqiu Xue, and Hyuck Park

Slow groundwater flow and mass transport processes in mudstone sometimes exhibit non-Darcian flow. For example, it is known that some mudstone shows semipermeable properties because of its negative charge of clay minerals and narrow pore throats (Marine and Fritz, 1981). In such formations, osmotic flow, water flow driven by osmotic pressure, occurs and it induces pore pressure change in low-permeability or hydraulically isolated area (Marine and Fritz, 1981). If large pore-water concentration difference exists in tight and clay-rich formation, osmosis-induced pore pressure can reach to about 20MPa(Neuzil, 2000). Change of pore pressure causes deformation of porous medium.  Osmosis-induced pore pressure change can cause deformation of porous medium (Greenberg et al., 1973: Noy et al., 2004) and it is possible that large concentration difference causes rock deformation or destruction in semipermeable formations.

The purpose of this study is to establish a model which describes pressure behavior, solute transport, and deformation of semipermeable mudstone and to discuss the validity of the model through comparing the model result and the results obtained from laboratory experiments. The numerical model is established by coupling the equations of solute transport and pressure behavior in semipermeable mudstone(for example Malusis et al., 2012), and that of poroelasticity (for example Wang, 2000). For laboratory experiments, core samples with 50mm in diameter and 30mm in height were prepared from mudstone samples collected from Neogene formation in Japan. NaCl solution with 10 g/L higher than that of pore water was contacted to one of the surfaces of the sample, and all the other surfaces were sealed with silicone rubber. Longitudinal deformation of the sample surface was measured. Here, optical fiber sensing technique was used to measure strain behavior, and hence, it was possible to measure strains at multi point of the sample. The measurement was continued more than 240hr.

In the presentation, the comparison of results obtained from experiments and calculations will be shown and the significance will be discussed.

How to cite: Hirota, S., Tokunaga, T., Aichi, M., Xue, Z., and Park, H.: Coupled chemical osmosis and rock deformation processes in semipermeable mudstone- theoretical and experimental approaches-, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13798, https://doi.org/10.5194/egusphere-egu2020-13798, 2020.

EGU2020-15260 | Displays | ERE4.1

ECCSEL Infrastructure for Isotope Characterization of Reservoirs for Subsurface CO2 Storage

Ingar Johansen, Farhana Huq, Christian Alexander Schöpke, and Viktoriya Yarushina

A potential solution to reduce the emission of CO2 in the atmosphere is to store CO2 in subsurface reservoirs. This may be in depleted gas/oil reservoirs, saline aquifers or other porous geological formations, both on shore and off shore. To avoid any hazardous incidents, it is of high importance that the reservoirs can be proven leak free and that there is a good communication within the reservoir.

A useful tool to determine the storage quality of a reservoir is to use Strontium Residual Salt Analyses (Sr-RSA). This is an efficient tool to determine the fluid connectivity of the reservoir and the caprock in horizontal and lateral directions. In addition, it can reveal the presence of barriers and baffles in a geological perspective. Sr-isotope data can also be used to calculate the extent of the barriers and moreover, use of Carbon and Oxygen isotopes measured in cemented barriers can help reveal the history of the barriers (time and temperature of the cementations).

The Geochemistry laboratory at Institute for Energy Technology (IFE) has partially been financed by Horizon 2020 and is a part of the ECCSEL infrastructure. The multi collector (MC)-ICP-MS at IFE’s Geochemical Analysis Lab performs high-precision, high-resolution, and simultaneous measurements of isotope ratios in a wide range of isotope systems. Other Isotopes systems of interest for characterize CO2 storage reservoirs, traditional and non-traditional stable and radiogenic isotopes (Sr, Pb and U, Li, Mg, Ca, Mg, Fe, Cd, Cu, Zn, and Ni), geo- and thermo-chronology, tracing fluid flow patterns, fingerprinting sources of materials, quantifying interactions in biogeochemical systems, and monitoring environmental systems.

By coupling the MC-ICP-MS to IFE’s LA-HR-ICP-MS, the simultaneous analysis of novel isotopes and trace elements in solid materials can be achieved. The laboratory is a state-of-the-art facility for measuring isotope systems to produce data to interpret: biogeochemical reaction rates and products, tracking fluid migration, evaluating fluid/rock interactions and detect CO2 leakage in cap rock.

How to cite: Johansen, I., Huq, F., Schöpke, C. A., and Yarushina, V.: ECCSEL Infrastructure for Isotope Characterization of Reservoirs for Subsurface CO2 Storage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15260, https://doi.org/10.5194/egusphere-egu2020-15260, 2020.

EGU2020-18434 | Displays | ERE4.1

Microbial Redox Reactions During Underground Storage of Hydrogen

Martin Krueger and Anja Dohrmann

Underground storage of hydrogen (H2) could be an alternative or important supplement to energy storage. However, there is still lack of knowledge about fundamental biogeochemical aspects of underground H2 storage. The BMBF-funded project H2_ReacT investigates fundamental petrophysical, geochemical and biogeochemical aspects of underground H2 storage. The work presented here addresses the microbial consumption of H2 and the involved microorganisms at potential underground storage sites.

Microbial reactions that consume H2 are still a major uncertainty factor for underground H2 storage. Microbial life is widespread in the crust of the earth and geological formations suitable for underground H2 storage often contain a deep subsurface biosphere. Thus, an underground H2 storage site needs to be seen as a habitat for microorganisms. Microbial activity at the H2 storage site might affect the stored H2 as well as the integrity of the storage site itself. A specific interest is to gain information about microbial activity that might result in a loss of stored hydrogen as well as the production of unwanted metabolic products e.g. H2S. The importance of specific conditions with relevance for underground hydrogen storage i.e. elevated pressure, high temperature and rock material, will be addressed.

Preliminary results showed the consumption of H2 by indigenous microorganisms from a porous rock reservoir fluid. Hydrogen was consumed at different temperature and pressure conditions relevant for underground H2 storage. Here, hydrogen consumption rates were strongly influenced by temperature and pressure. Currently effects of several geochemical parameters on microbial H2 consumption are studied in more detail. Furthermore, molecular biological approaches are used to identify the involved microorganisms.

How to cite: Krueger, M. and Dohrmann, A.: Microbial Redox Reactions During Underground Storage of Hydrogen, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18434, https://doi.org/10.5194/egusphere-egu2020-18434, 2020.

EGU2020-18548 | Displays | ERE4.1

Geological Storage of Hydrogen: Learning from natural analogues

Christopher J. McMahon, Jennifer J. Roberts, Gareth Johnson, Zoe K. Shipton, and Katriona Edlmann

The potential role of hydrogen in achieving a net zero emissions future is gaining traction. A hydrogen economy would likely be supported by geological formations in which to store hydrogen at times of excess and to extract in times of demand, akin to subsurface natural gas storage.

Minimising the risk of hydrogen leakage is not only important to support the safety case for geological storage, but also to constrain risk of any economic losses from the migration of hydrogen from its intended storage formation. As such, deepening scientific understanding of the processes governing hydrogen containment and leakage is fundamental for: (a) prospecting of natural hydrogen plays, (b) informing effective site selection for geological hydrogen storage, and (c) the design and performance requirements of appropriate monitoring of these sites.

Several earth processes generate hydrogen, and naturally occurring subsurface hydrogen accumulations and hydrogen seeps (where hydrogen is seeping to surface) present opportunity for study to further knowledge on geological containment of hydrogen. Here, we present a synthesis of the available literature on natural analogues for hydrogen storage and seepage around the world to elicit the factors governing containment/leakage and seep characteristics. We also consider how learnings from other subsurface energy sectors such as geological CO2 storage might be translated and applied to hydrogen storage.

We find that currently there are few natural analogues for hydrogen – there are only eight hydrogen seeps and fewer hydrogen accumulations documented in the scientific literature (though we postulate that other sites of hydrogen accumulation and seepage may exist but are yet to be documented). For all known analogues, the hydrogen is thought to derive from deep seated processes (e.g. serpentenization) rather than superficial bacteriological or other processes. Hydrogen seepage can occur in clusters or in isolation, and the location, distribution and morphology of seeps are controlled by geological factors such as regional stress, occurrence of faults, and properties of the host rock. These factors are similar to those governing CO2 seepage, but we note differences, too. One documented hydrogen accumulation is shallow (80-150m). Hydrogen and methane occur in different proportions at different depths in the reservoir complex. This implies that different rock properties constitute a seal/reservoir for methane and hydrogen. The parameters that define a hydrogen “play” may therefore be different to a hydrocarbon play.

Overall very little is known about how hydrogen migrates and is trapped in the subsurface, and there are few studies of natural analogues. Our work highlights the need for further research around the factors that govern hydrogen fluid flow, and thus the degree to which knowledge of fluid flow of other geofluids can be translated and applied to ensure effective and secure geological hydrogen storage.

How to cite: McMahon, C. J., Roberts, J. J., Johnson, G., Shipton, Z. K., and Edlmann, K.: Geological Storage of Hydrogen: Learning from natural analogues, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18548, https://doi.org/10.5194/egusphere-egu2020-18548, 2020.

EGU2020-18982 | Displays | ERE4.1

Pore Scale Analysis of Suitability for Geological Carbon Storage, Implications for the UK Geoenergy Observatories Project

Ryan L Payton, Mark Fellgett, Andrew Kingdon, Brett Clark, and Saswata Hier-Majumder

Geological carbon storage (GCS) has been identified as a crucial process in tackling rising anthropogenic CO2 emissions. We examine 4 sandstone cores from the Scottish Middle Coal Measures Formation at the UK Geoenergy Observatories (UKGEOS) site in Glasgow using X-ray micro computed tomographic images to assess the carbon storage capacity. Each 3D microtomographic image was processed by binary segmentation to extract the macroporosity from the greyscale images, pore network analysis to establish the effective porosity, and permeability simulation using a finite volume solver. We compare this location to 7 samples from the Wilmslow Sandstone Formation in Sellafield as a precursor analysis of the laterally equivalent Sherwood Sandstone at the under construction Cheshire UKGEOS site. We find a significant difference in porosity and permeability between the two sites with Sellafield samples showing a porosity range of 9.73-25.31% whilst Glasgow samples display a range of 0.38-1.65%. The Sellafield samples also show a significant proportion of connected porosity ranging between 8.85 and 25.26%, whilst no connected porosity was found in the Glasgow samples. This is deemed due to the presence of a ubiquitous cement phase occupying up to 26.28% of the sample volume, significantly reducing the viability for fluid injection and therefore GCS at the Glasgow site. Carbon storage is dependent on the availability of pore space for mineralisation and the pore connectivity which allows for fluid flow of CO2. Our measured values of porosity and permeability also indicate that the Sellafield site and sandstones similar to the samples from this site will be highly effective as CCS target formations.

How to cite: Payton, R. L., Fellgett, M., Kingdon, A., Clark, B., and Hier-Majumder, S.: Pore Scale Analysis of Suitability for Geological Carbon Storage, Implications for the UK Geoenergy Observatories Project, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18982, https://doi.org/10.5194/egusphere-egu2020-18982, 2020.

EGU2020-19141 | Displays | ERE4.1

Hydrogen storage in porous media: learnings from analogue storage experiences and knowledge gaps

Juan Alcalde, Niklas Heinemann, Michelle Bentham, Cornelia Schmidt-Hattenberger, and Johannes Miocic

Underground hydrogen storage (UHS) in porous media has been proposed as an effective and sustainable energy storage method to balance renewable energy supply and seasonal demand. To determine the potential for and conduct realistic risk assessments of the UHS technology, learnings from more mature underground fluid storage technologies, such as underground storage of natural gas (UGS) or CO2 (UCS), can be used. Here we discuss the caveats related to the use of these technologies as analogues to UHS and highlight current knowledge gaps that need to be addressed in future research to make UHS a secure and efficient technology.

Abiotic and biotic reactions between the rock and the fluids, often not considered in UCS and UGS operations, play an important role in UHS and can change the chemical environment in the reservoir dramatically. The mineralogy of the reservoir and cap rocks, as well as the in-situ pore fluid chemistry, is of vital importance and the characterisation efforts should not be limited to the reservoir quality.

The risk assessment of UHS operation may follow similar production cycles as in UGS, but there are important lessons to be learnt from UCS. UCS aims to store injected gas permanently and different CO2 trapping mechanisms are contributing to storage security. Residual trapping, which locks parts of the CO2 within the pore space, may reduce the commercial profitability in UHS, but can assist to mitigate potential leakage of hydrogen. The dissolution of hydrogen in the pore water will likely play a minor role in UHS compared to UCS, while the precipitation of minerals containing hydrogen during UHS has not yet been appropriately investigated.

The main storage process in gas storage is the accumulation of buoyant fluid underneath a low-permeability cap rock in a three-dimensional trap. Storage sites are determined by different parameters: UGS is mainly used in depleted gas fields (hence sites with proven gas storage security), while UCS sites are usually located deeper than 800m for efficiency reasons, under conditions at which CO2 is present as a high-density supercritical phase. None of these restrictions are a pivotal for UHS and a new set of constrains should be formulated specifically designed to the properties of hydrogen. These must involve:

  • The unique properties of hydrogen (high diffusivity and low density and, thus, high buoyancy) require potential storage sites to have well-understood cap rocks with minimal diffusion and capillary leakage risk.
  • A reservoir architecture and heterogeneity that guarantees economically sensible injection and withdrawal rates by choosing sites, which minimise the isolation of hydrogen from the main plume during UHS operations.
  • Site monitoring protocols will also need to be re-evaluated for different scales, as well as for the dynamic properties of hydrogen, such as low density and fluid mobility.

It is certain that leakage along abandoned wells, the main risk for leakage in UCS and UGS, will also pose a risk to the containment of injected hydrogen. Therefore, hydrogen storage site locations require a comprehensive investigation into abandoned and operational (deep) petroleum and (shallow) water exploration and production wells.

How to cite: Alcalde, J., Heinemann, N., Bentham, M., Schmidt-Hattenberger, C., and Miocic, J.: Hydrogen storage in porous media: learnings from analogue storage experiences and knowledge gaps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19141, https://doi.org/10.5194/egusphere-egu2020-19141, 2020.

EGU2020-20701 | Displays | ERE4.1

CCS potential of the Triassic alluvial succession in the eastern Horda Platform

Camilla Würtzen, Johan Petter Nystuen, Reidar Müller, Johnathon Osmond, Jan Inge Faleide, and Ivar Midtkandal

The Triassic continental succession located in the eastern side of the Horda Platform (northern North Sea) represents a potential supplementary CO2 storage formation to the principal Jurassic sandstones above. Several 1-2.5 kilometer-thick packages of Triassic sediment lie within a series of large eastward-dipping half-grabens east of the Viking Graben. The deeply buried Triassic deposits (1.8-3 km) within the prospective area are confined between the Øygarden Fault Zone to the east and the Vette Fault Zone to the west, the latter separating the prospective area from the Troll hydrocarbon fields. Despite extensive petroleum exploration within the Horda Platform, the entire Triassic interval remains largely untested and its storage potential poorly understood. The lack of wellbore penetrations and 3D seismic coverage means that reservoir quality can only be assessed using conceptual predictions and analogue studies.

A seismic stratigraphic model is built using available 2D and 3D seismic and integrated well log data to discern the Triassic basin fill history and structural development of the area. The stratigraphic succession is subdivided into seismic facies, where reflection patterns infer depositional characteristics. A shift in log facies trend between mud- and sand-rich intervals indicates a variance in subsidence rate and sedimentation supply related to tectonic displacement rate and climate. Visual analyses of the seismic data along key horizons also reveal depositional features such as channels, hanging wall fans, and footwall fans. The location and distribution of the channels are mapped in order to assess the connectivity of possible storage bodies.

Analogous Triassic sandstone reservoirs of the Snorre field (Tampen Spur) roughly 125 km away are similar in terms of stratigraphic facies and mineralogy. The Snorre field reservoirs are dominantly subarkosic and arkosic sandstones with illite-smectite and chlorite-smectite and lesser amounts of kaolinite and chlorite clay minerals within the matrix and pore spaces. Furthermore, the Triassic succession is composed of sandstones and mudstones deposited in fluvial systems with subordinate alluvial plain environments. The sandstones possess highly variable poro-perm values closely related to the depositional facies. As the Horda Platform sediments were deposited more proximal to the source than those of the Tampen Spur, it is expected that coarser grain sizes persist within the prospective interval, but perhaps at a lower degree of maturity and higher grain size variability. Overall, this preliminary assessment suggests that thick Triassic channel sandstones present in the eastern Horda Platform have promising CCS potential.

 

Keywords. Triassic, Horda Platform, CCS, basin fill history, seismic facies, tectonic displacement, climate, reservoir quality

How to cite: Würtzen, C., Nystuen, J. P., Müller, R., Osmond, J., Faleide, J. I., and Midtkandal, I.: CCS potential of the Triassic alluvial succession in the eastern Horda Platform , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20701, https://doi.org/10.5194/egusphere-egu2020-20701, 2020.

EGU2020-20843 | Displays | ERE4.1

Thermodynamics of Hydrogen-mixed gases

Aliakbar Hassanpouryouzband, Katriona Edlmann, Niklas Heinemann, and Mark Wilkinson

Increasing atmospheric CO2 concentration will continue to be a risk if we continue to use fossil fuels as our main energy source. Hydrogen is the ideal low carbon fuel/energy vector to replace fossil fuels facilitating the energy transition, without further increasing gas atmospheric CO2 concentrations. Thermodynamic characterisation of hydrogen and hydrogen mixed gases is important to solve the challenging production and storage issues in a hydrogen-based economy. Thermodynamic characterisation is vital to design more efficient and more economic production and storage processes, and must be undertaken as a crucial first step for wide application of hydrogen-based fuels and their storage. Here we applied a highly accurate equation of state, namely, GERG-2008, to predict various thermodynamic properties (e.g. phase behaviour, density, viscosity, compressibility, and heat capacity) of hydrogen when mixed with other gases including: CO2, CH4, N2, and natural gas. Given the important influence of other constituents in the hydrogen gas stream on the thermodynamic properties of hydrogen, such thermodynamic data could be used for efficient design, development, and deployment of innovative hydrogen production, transport, blending and storage techniques. Understanding the thermodynamic characterisation of hydrogen and hydrogen mixed gasses is particularly important for geological hydrogen storage, where the thermodynamic properties of the injected gas in equilibrium with existing fluids in the storage reservoir is required to estimate the storage capacity. The data is provided over wide range of pressure, temperature, and molar combination representing the range of fuel blending, applications and storage conditions for hydrogen.

How to cite: Hassanpouryouzband, A., Edlmann, K., Heinemann, N., and Wilkinson, M.: Thermodynamics of Hydrogen-mixed gases, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20843, https://doi.org/10.5194/egusphere-egu2020-20843, 2020.

EGU2020-21396 | Displays | ERE4.1

Aquifer Thermal Energy Storage (ATES) systems - current global practical experiences

Simon Schüppler, Paul Fleuchaus, Bas Godschalk, Guido Bakema, Roman Zorn, and Philipp Blum

As most of the industrial nations are located in the moderate climate zone with distinct summer and winter, global heating and cooling supply is less a matter of energy shortage than an issue of seasonal storage. Aquifer Thermal Energy Storage (ATES ) is capable of storing large energy volumes to bridge the seasonal mismatch between demand and supply of heating and cooling systems. However, there is a discrepancy in global ATES development, since more than 80 % of all ATES system are currently operating in the Netherlands and Scandinavia, which is mainly attributed to techno-economic barriers. Thus, this work analyses the technical performance of ATES based on monitoring data from 73 low temperature Dutch ATES systems. The analysis reveals total abstraction of 30 GWh of heat and 32 GWh of cold per year with average abstraction temperatures of 10 °C and 15 °C in summer and winter, respectively. However, while the temperature difference between abstraction and injection is 3-4 K smaller compared to the optimal design, the stored and abstracted amount of thermal energy is 50 % lower than the licensed capacities. This suggests inadequate interaction between the energy system and the aquifer as a result of the insufficient charging process of the subsurface. Nevertheless, the data showed only small thermal imbalances and small temperature losses during the storage period. Based on the comprehensive analysis, valuable conclusions can be drawn on the optimizations needs of current and future ATES projects.

 

How to cite: Schüppler, S., Fleuchaus, P., Godschalk, B., Bakema, G., Zorn, R., and Blum, P.: Aquifer Thermal Energy Storage (ATES) systems - current global practical experiences , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21396, https://doi.org/10.5194/egusphere-egu2020-21396, 2020.

EGU2020-21528 | Displays | ERE4.1

Assessment of CO2-EOR and its geo-storage potential in oil reservoirs of Precaspian basin, Kazakhstan

Nurlan Seisenbayev, Yerdaulet Abuov, Zhanat Tolenbekova, and Woojin Lee

Precaspian basin is the most petroliferous basin in Kazakhstan with more than 100 years of history of the oil and gas industry. The economy of the country has been depending on the revenues coming from the sale of Precaspian oil. Nevertheless, the average oil recovery rate in the country remains low around 30-35% and its government planned to increase the recovery rate to 55-60%. The high oil recovery rate could be achieved by enhanced oil recovery (EOR) methods by injecting diverse inert gases and liquids. The global challenge of excessive CO2 emissions makes an EOR with CO2 injection (CO2-EOR) a good candidate because the anthropogenic CO2 emission could be a good source of the injection gas. Depleted oil reservoirs are the first targets for the implementation of carbon storage. The basin contains 178 oil and gas fields distributed in pre-salt and post-salt sections divided by the huge Kungurian salt bed that deformed into domes throughout the basin. A set of suitable reservoir parameters (Original Oil In Place (OOIP), depth, API, pressure, porosity, permeability, initial oil saturation) for CO2-EOR have been identified by earlier works of researchers based on previous experience of the petroleum industry and used to screen the oil reservoirs of the Precaspian basin. Thirty-four reservoirs of the basin were identified to be suitable for CO2-EOR or CO2 storage. The effective CO2 storage capacity of the reservoirs has been estimated using the Carbon Sequestration Leadership Forum (CSLF) method. The previous estimation of the storage capacity of 178 reservoirs was 179.2 Mt of CO2 however, after the CO2-EOR screening, the capacity decreased to 24.4 Mt. The mapping of CO2 sources and investigation of CO2 amount released from each CO2 source in the Precaspian basin will contribute to the CO2 source-CO2 sink matching to decide the most feasible CCS options. In addition, the analysis of fault intensity and seismicity in suitable reservoir-seal pairs could have important implications for the safety of CO2 storage.

How to cite: Seisenbayev, N., Abuov, Y., Tolenbekova, Z., and Lee, W.: Assessment of CO2-EOR and its geo-storage potential in oil reservoirs of Precaspian basin, Kazakhstan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21528, https://doi.org/10.5194/egusphere-egu2020-21528, 2020.

EGU2020-21554 | Displays | ERE4.1

CO2 storage capacity of Kazakhstan

Yerdaulet Abuov and Woojin Lee

Carbon Capture and Storage (CCS) can provide the solution for the impending challenge of climate change until Renewable Energy Sources (RES) can take over a significant role in global energy market. Kazakh government developed the “Green Economy” plan to increase the share of RES in the energy sector to 50% by 2050. In November 2016, Kazakhstan ratified Paris Agreement to cut its GHG emissions from the base year of 1990 by 15% and 25% under different conditions. Previous research efforts in TIMES energy system modeling of GHG emissions has shown that satisfying the Paris Agreement terms require full phasing out of coal from residential sector heating in favor of RES. Given the current 1% share of RES in the energy sector, the energy demands of the country cannot be met with coal being excluded from consumption. Given the large fossil fuel resources of the country and coal-dependent economy, CCS may play a major role in the decarbonization of the country while allowing to rely on coal. “KazCCUS” is the first CCS-related project in post-soviet countries which aims to develop CCS related technologies in Kazakhstan. This research aims to identify proper geologic structures in sedimentary basins and estimate their storage capacity. Governmental oil and gas field database that was compiled from field operator surveys and publicly available literature was used to identify horizons with suitable reservoirs-seal characteristics. CO2 storage options were identified in 6 sedimentary basins of the country: Preacaspian, Mangyshlak, Ustyurt, South Torgay, Chu-Sarysu and Zaysan basins. The effective CO2 storage capacity in oil reservoirs, gas reservoirs and saline aquifers were estimated using the methods developed by Carbon Sequestration Leadership Forum and US DOE. The total effective CO2 storage capacity in 6 basins was  estimated to be 204 Mt, 610 Mt, and 403 Gt in oil reservoirs, gas reservoirs, and saline aquifers, respectively. Sedimentary layers without intense faulting and suitable reservoir-seal pairs were found in 4 petroliferous sedimentary basins. The carbonate platforms in the pre-salt section of Precaspian basin and post-salt clastic reservoirs trapped by salt-dome related traps provide potential storage sites for CO2. Jurassic sandstone successions in Mangyshlak, South Torgay and Ustyurt basins are also good candidates for geologic CO2 storage and they all have a thick seal or caprock system that were holding hydrocarbon fluids for geologic time scale. The results of this study suggest that there is a huge potential for CCS in Kazakhstan and CCS can be deployed in mature fields of oil-producing basins. In addition, CO2-EOR is an option for operating oil fields. The country can have both environmental and economic benefits from CO2 storage and this will also contribute to the compliance with Paris Agreement terms. This research may serve as a baseline for future CCS deployment strategy in Kazakhstan.

How to cite: Abuov, Y. and Lee, W.: CO2 storage capacity of Kazakhstan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21554, https://doi.org/10.5194/egusphere-egu2020-21554, 2020.

EGU2020-21758 | Displays | ERE4.1

Effects of geological heterogeneity on fluid distribution and pressure propagation in a shallow, stacked aquifer system at the ECCSEL Svelvik CO2 Field Lab, Norway

Anja Sundal, Alv Arne Grimstad, Ulrich W. Weber, Wolfram Kurschner, Klaus Hagby, and Cathrine RIngstad

The ECCSEL Svelvik CO2 Field Lab is a test site for shallow CO2 injection operated by SINTEF, where the aim is to improve monitoring techniques and extend the knowledge base for storing CO2 underground in deep saline aquifers as a climate mitigation strategy. The test site is located in a Holocene ice contact deposit near Drammen in the Oslofjord. Test injection is possible at 65 m depth. There has been extensive research focused on increasing the understanding of monitoring methods for deep injection of CO2 and the (short term) migration of CO2, based on experiments performed in this shallow aquifer. To maximize the value of data collected in the shallow experiments a solid geological model is fundamental to enable prediction of how water and gas will behave in the reservoir. Various thicknesses of reservoir layers and degree of internal heterogeneity (clinoforms, unconformities, faults) are observed. Analysis of new data from wells (cuttings sediment samples, wire line logs) and comparison with existing data (e.g. seismic lines, georadar profiles) indicate upwards shallowing and upwards freshening trends through the stratigraphic succession, i.e. variation in palynomorph assemblages. Groundwater flux and aquifer connectivity was evaluated through comparison of water chemistry, noble gas content (the ICO2P project) as well as resistivity- and pressure-logging in upper (fresh) and lower (saline) parts. Analysis of the tidal pressure signal in the deep part of the aquifer gives an indication of the degree of communication between the layers of the aquifer. The areal extent of (semi-)sealing layers of mud, as well as intra-reservoir geological heterogeneity (inclined, graded sandy beds with thin, muddy lamina) affects CO2 distribution in the test reservoir, and is likely to lead buoyant fluids along preferential flow paths. Facies models include North-South progradational patterns and are represented in anisotropic property distributions (Petrel - Schlumberger) for fluid flow simulations (Eclipse - Schlumberger). Predicted CO2 flux is towards the North, below what appears to be locally extensive flow baffles. Integrated data analysis has improved the geological understanding of the Svelvik stacked aquifer system, which may be utilized in future applications to improve monitoring methods for safe large-scale CO2 storage.

How to cite: Sundal, A., Grimstad, A. A., Weber, U. W., Kurschner, W., Hagby, K., and RIngstad, C.: Effects of geological heterogeneity on fluid distribution and pressure propagation in a shallow, stacked aquifer system at the ECCSEL Svelvik CO2 Field Lab, Norway, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21758, https://doi.org/10.5194/egusphere-egu2020-21758, 2020.

EGU2020-18150 | Displays | ERE4.1

Tracer Design and Gas Monitoring of a CO2 Injection Experiment at the ECCSEL CO2 Field Lab, Svelvik, Norway

Ulrich Wolfgang Weber, Katja Heeschen, Martin Zimmer, Martin Raphaug, Klaus Hagby, Cathrine Ringstad, and Anja Sundal

The ECCSEL Svelvik CO2 Field Lab outside Oslo has been set up for water and CO2 injection experiments. At the site, ongoing and future investigations on monitoring techniques for carbon capture and storage (CCS) shall support the development of CCS as a climate change mitigation technology in Norway.

In 2019, four 100 m deep injection wells with a sophisticated physical monitoring setup were established. For chemical monitoring a fluid sampling system at injection depth was installed and coupled to a continuously measuring mass spectrometer for observing CO2 distribution. Alongside, a network of soil gas flux chambers (LI-COR 8100) were set up to monitor possible surface leakages.

The field lab is placed in a sand quarry within the Svelvik Ridge consisting of Holocene, siliciclastic sediments. Injection is conducted into a saltwater aquifer at 65m, supposedly sealed by clay strata. We sampled the upper fresh water aquifer at 6.5m depth and the storage aquifer at 64 - 65 m depth on dissolved gases before injection in order to design a noble gas tracer for the CO2 injection experiment. Elevated helium concentrations in the saline aquifer indicate natural radiogenic accumulation; meanwhile krypton concentrations were not naturally increased.

During an injection experiment in fall 2019, we added noble gases, i.e. krypton and helium, in two subsequent injection cycles, three days and one week, respectively. Outgassing was observed and high helium concentrations verified a leakage at the injection well, which we quantified with a flux chamber.

How to cite: Wolfgang Weber, U., Heeschen, K., Zimmer, M., Raphaug, M., Hagby, K., Ringstad, C., and Sundal, A.: Tracer Design and Gas Monitoring of a CO2 Injection Experiment at the ECCSEL CO2 Field Lab, Svelvik, Norway, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18150, https://doi.org/10.5194/egusphere-egu2020-18150, 2020.

ERE4.2 – Towards a safe nuclear waste repository – assessment of barrier integrity, geoscientific, technological, societal and regulatory challenges and approaches

EGU2020-12231 | Displays | ERE4.2

Learning from 1 billion year old copper

Desmond Moser, James Noël, Anna Dobkowska, Dmitrij Zagidulin, Jessica Perritt, Peter Keech, Mehran Behazin, Jeff Binns, Gabriel Arcuri, and Brian Langelier

In Canada, the Nuclear Waste Management Organization (NWMO) is responsible for the long-term management of spent nuclear fuel, which involves sealing used fuel bundles in copper-coated carbon steel used fuel containers (UFC) and emplacing them ~500 m underground in a deep geological repository (DGR). In this plan, copper plays a vital role in ensuring the safety of the DGR as it is intended to serve as a corrosion barrier for greater than one million years. Veins and pods of natural copper have long been known to occur in the Lake Superior region of North America where they have been culturally significant to Indigenous peoples for millennia. The natural Lake Superior copper deposits were emplaced close to one billion years ago in lithosphere which has since had a protracted history of glacial overrides and related isostatic adjustment events. In light of this longevity, structural history and exposure to crustal fluids, it has the potential to hold many lessons for DGR specialists and society in general. We present two aspects of our approach. The first is an outline of our efforts to increase cultural competency of non-indigenous scientists in our group while building an understanding of the Indigenous Knowledge system and how it can be respectfully and effectively applied to research. This includes respectful ways in which to collect, and learn from, copper samples. This work directly relates to the important relationships in the context of the NWMO Indigenous Knowledge policy, Reconciliation policy and how both policies apply to the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP). In this context we will also present our early field and laboratory observations of natural copper properties through an integrated analysis of chemical and orientation microstructure in tandem with electrochemical behaviour. Techniques in the laboratory workflow include electron microscopy (EDS, EBSD) and atom probe tomography to map impurities and microstructure relative to manufactured wrought copper (phosphorus-doped oxygen free); Auger electron and X-ray photoelectron spectroscopies to determine surface and near-surface composition and chemical environment; and electrochemical methods such as corrosion potential measurements and potentiodynamic polarization scans to probe the corrosion performance. These measurements may inform container design aspects such as optimal fabrication and the role of impurities in corrosion behaviour of electrodeposited and cold spray-deposited copper in a DGR over geological timescales. Taken together, our aim is to come to an appropriately comprehensive understanding of the cultural, geological and material corrosion aspects of natural copper that has persisted for a time span three orders of magnitude greater than the DGR design requirements. It is our hope that this learning approach to ancient natural copper will play a positive role in seeking social license for DGR planning, while having value for societal education in the global challenge of geostorage.

How to cite: Moser, D., Noël, J., Dobkowska, A., Zagidulin, D., Perritt, J., Keech, P., Behazin, M., Binns, J., Arcuri, G., and Langelier, B.: Learning from 1 billion year old copper, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12231, https://doi.org/10.5194/egusphere-egu2020-12231, 2020.

EGU2020-2474 | Displays | ERE4.2

2019 Performance Assessment Calculations for the Recertification of the Waste Isolation Pilot Plant

Todd Zeitler, James Bethune, Sarah Brunell, Dwayne Kicker, and Jennifer Long

The Waste Isolation Pilot Plant (WIPP), located in southeastern New Mexico, has been developed by the U.S. Department of Energy (DOE) for the geologic (deep underground) disposal of transuranic (TRU) waste. Containment of TRU waste at the WIPP is regulated by the U.S. Environmental Protection Agency (EPA) according to the regulations set forth in Title 40 of the Code of Federal Regulations (CFR), Part 191. The DOE demonstrates compliance with the containment requirements according to the Certification Criteria in Title 40 CFR Part 194 by means of performance assessment (PA) calculations performed by Sandia National Laboratories (SNL). WIPP PA calculations estimate the probability and consequence of potential radionuclide releases from the repository to the accessible environment for a regulatory period of 10,000 years after facility closure.

The models used in PA are maintained and updated with new information as part of an ongoing process. Improved information regarding important WIPP features, events, and processes typically results in refinements and modifications to PA models and the parameters used in them. Planned changes to the repository and/or the components therein also result in updates to WIPP PA models. WIPP PA models are used to support the repository recertification process that occurs at five-year intervals following the receipt of the first waste shipment at the site in 1999.

The 2019 Compliance Recertification Application (CRA-2019) is the fourth WIPP recertification application submitted for approval by the EPA. A PA has been executed by SNL in support of the DOE submittal of the CRA-2019. Results found in the CRA-2019 PA are compared to those obtained in the 2014 Compliance Recertification Application (CRA-2014) PA in order to assess repository performance in terms of the current regulatory baseline. This presentation includes a summary of the changes modeled in the CRA-2019 PA, as well as the estimated releases over the assumed 10,000-year regulatory period. Changes incorporated into the CRA-2019 PA included repository planned changes, parameter updates, and refinements to PA implementation.

Overall, the total normalized releases for the CRA-2019 PA have increased at all probabilities compared to those from the CRA-2014 PA. Releases from each of the four potential release mechanisms tracked in WIPP PA (cuttings and cavings, spallings, releases from the Culebra formation, and direct brine releases) have also increased at all probability levels. Cuttings and cavings releases continue to dominate total releases at high probabilities and direct brine releases continue to dominate total releases at low probabilities. Although the calculated releases have increased, the total normalized releases continue to remain below regulatory limits. As a result, the CRA-2019 PA demonstrates that the WIPP remains in compliance with the containment requirements of 40 CFR Part 191.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.. This research is funded by WIPP programs administered by the Office of Environmental Management (EM) of the U.S. Department of Energy. SAND2020-0131A

How to cite: Zeitler, T., Bethune, J., Brunell, S., Kicker, D., and Long, J.: 2019 Performance Assessment Calculations for the Recertification of the Waste Isolation Pilot Plant, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2474, https://doi.org/10.5194/egusphere-egu2020-2474, 2020.

EGU2020-2300 | Displays | ERE4.2

The role of microorganisms in the bentonite barrier of high-level radioactive waste repositories

Nicole Matschiavelli, Magdalena Dressler, Tom Neubert, Sindy Kluge, Ariette Schierz, and Andrea Cherkouk

The global production of 12,000 metric tonnes of high-level radioactive waste (HLW) every year is a big challenge with respect to its safe long-term storage. In the favored multi-barrier system, bentonite is discussed as a geo-technical barrier in many disposal programs worldwide. The bentonite seals the space between the canister containing the HLW and the surrounding host rock, thereby fulfilling two major tasks: 1) slow down the process of corrosion when water enters the disposal site, and 2) hinder the discharge of radionuclides into the bio-geosphere in case of a leaking canister. Due to their metabolic activity, microorganisms could significantly influence the properties of the bentonite barrier. In order to investigate the metabolic potential of naturally occurring microorganisms, we conducted anaerobic bentonite-slurry experiments containing uncompacted bentonite and a synthetic Opalinus Clay pore water solution. Within one-year incubation at 30 and 60 °C, lactate- or H2-stimulated microcosms at 30 °C showed the dominance and activity of strictly anaerobic, sulfate-reducing and spore-forming microorganisms. Consequently, hydrogen sulfide gas was generated in the respective set ups, leading to the formation of fractures and iron-sulfur precipitations. Experiments that incubated at 60 °C, showed the dominance of thermophilic bacteria, independent of the presence of substrates. The respective set-ups showed/revealed no significant changes in the analyzed bio-geochemical parameters. The obtained results clearly show that indigenous microorganisms evolve in a temperature- and substrate-dependent manner. The formed metabolites can potentially affect the dissolution behavior of minerals and ions within the bentonite as well as corrosion processes and require further investigations.

How to cite: Matschiavelli, N., Dressler, M., Neubert, T., Kluge, S., Schierz, A., and Cherkouk, A.: The role of microorganisms in the bentonite barrier of high-level radioactive waste repositories, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2300, https://doi.org/10.5194/egusphere-egu2020-2300, 2020.

EGU2020-3966 | Displays | ERE4.2

Biogenic safety of clay barrier materials for radioactive waste repository database

Alexey Safonov, Nadezhda Popova, Elena Spirina, Elena Abramova, Nadezhda Philippova, Victoria Jarkova, and Kirill Boldyrev

Clay minerals are widely used as materials for construction of engineered barriers for nuclear waste and spent fuel repositories all over the world due to perfect isolation properties and high sorption capacity. Unwanted microbiological processes that occur in geological repository can cause deterioration of clay barrier materials, which may significantly affect long-term safety of the repository. It is important to note that such unwanted processes could be caused both by native microbial population and bacteria brought in from outside during the construction of the repository.

This paper aims to develop a general concept that could be used to prove the risk of unwanted microbial processes’ occurrence in clay materials.  

Some features of mineral composition of clay materials, including the content of iron, sulphur, phosphorus, organic and mineral carbon, provide the basis for the concept. The ratios of free mono- and di-valent cations present in the solution (Na-K-Ca-Mg) are also taken into account. Another approach presumes microflora composition analysis by means of high-efficient 16S rRNA sequencing method. In addition, the results of several tests dedicated to microbial communities’ stimulation are discussed. These include tests on hydrogen or organic substance addition as electron donors with subsequent standard tests on metabolic activity evaluation, MTT test and respiration assessment of microbial population, which is represented by both planktonic cells and cells incorporated into biofilms. The developed concept was used to assess clay materials found in Russian Federation that could potentially be used to construct engineered safety barriers. These data formed the basis for the formation of a database of microbial safety of engineering barrier materials for radioactive waste storage.

How to cite: Safonov, A., Popova, N., Spirina, E., Abramova, E., Philippova, N., Jarkova, V., and Boldyrev, K.: Biogenic safety of clay barrier materials for radioactive waste repository database, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3966, https://doi.org/10.5194/egusphere-egu2020-3966, 2020.

EGU2020-3191 | Displays | ERE4.2

Investigating the Temperature Limits of Bentonite Backfilled Repositories: Coupled THMC Modeling, Lab Mockup Testing and Field Experiments

Jens Birkholzer, Liange Zheng, Jonny Rutqvist, Sharon Borglin, Chun Chang, Chunwei Chou, Yuxin Wu, and Tim Kneafsey

Compacted bentonite is commonly considered for use as backfill material in emplacement tunnels of nuclear waste repositories because of its low permeability, high swelling pressure, and retardation capacity of radionuclide. To assess whether this material can maintain its favorable features when undergoing heating from the waste package and hydration from the host rock, we need a thorough understanding of the thermal, hydrological, mechanical, and chemical evolution under disposal conditions. Laboratory and field tests integrated with THMC modeling have provided an effective way to deepen such understanding; however, most of this work has been conducted for maximum temperatures around 100°C. In contrast, some international disposal programs have recently started investigations to understand whether local temperatures in the bentonite of up to 200°C could be tolerated with no significant changes in safety relevant properties. For example, the United States disposal program is evaluating the feasibility of geological disposal of large spent nuclear fuel canisters that are currently in dry storage. Direct disposal of these canisters is attractive for economical and safety reasons, but faces the challenge of exposing the bentonite to significant temperatures increases. As a result, strong thermal gradients may induce complex moisture transport processes and bentonite-rock interactions while cementation and perhaps also illitization effects may occur, all of which could  strongly affect the bentonite properties.

Here, we present initial investigations of bentonite behavior exposed to strongly elevated temperatures. We first show results from coupled thermal, hydrological, mechanical and chemical (THMC) simulations of a generic nuclear waste repository in a clay formation with a bentonite-based buffer exposed to a maximum temperature of 200°C. Modeling results illustrate possible performance impacts, such as the time frame and condition of the early unsaturated phase during bentonite hydration, the porosity and permeability after the bentonite becomes fully saturated, and changing in swelling properties. We then discuss preliminary data from a bench-scale laboratory mockup experiment which was designed to represents the strong THMC gradients occurring in a “hot” repository, and we briefly touch on a full-scale field experiment to be conducted soon in the Grimsel Test Site underground research laboratory in Switzerland (referred to as HotBENT, with bentonite exposure from up to 200oC). 

How to cite: Birkholzer, J., Zheng, L., Rutqvist, J., Borglin, S., Chang, C., Chou, C., Wu, Y., and Kneafsey, T.: Investigating the Temperature Limits of Bentonite Backfilled Repositories: Coupled THMC Modeling, Lab Mockup Testing and Field Experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3191, https://doi.org/10.5194/egusphere-egu2020-3191, 2020.

EGU2020-3336 | Displays | ERE4.2

Which Processes could define Temperature Limits on the Outer Surface of a Container in a Disposal Facility ?

Guido Bracke, Eva Hartwig-Thurat, Jürgen Larue, Artur Meleshyn, Torben Weyand, and Ingo Kock

When the recommencement of the search for and selection of a site for a disposal facility for HLRW in Germany was stipulated by the Site Selection Act (StandAG 2017) in 2017, a precautionary temperature limit of 100 °C on the outer surface of the containers with high-level radioactive waste in the disposal facility section was set. This precautionary temperature limit shall be applied in preliminary safety analyses provided that the “maximum physically possible temperatures” in the respective host rocks have not yet been determined due to pending research. Therefore, this issue is addressed and discussed in this paper, contributing to “pending research” by a review of the literature.

This presentation briefly discusses a few examples of thermohydraulical, mechanical, chemical and biological processes in a disposal facility, because temperature limits are derived based on safety impacts regarding THMCB-processes. The temperature-dependent processes have been extracted from databases for features, events and processes (FEP-databases). Furthermore, it is dicussed if the feasibility to retrieve and recover HLRW is hampered at high temperatures.

It is concluded that a design temperature concerning single components of a disposal facility for the preservation of their features can be derived when a safety concept is established. However, the interactions of all relevant processes in a disposal concept must be considered to determine a specific temperature limit for the outer surface of the containers. Therefore, applicable temperature limits may vary for particular safety and disposal concepts in the following host rocks: rock salt, clay stone and crystalline rock.

Technical solutions for retrieval and design options for recovery seem to be viable up to temperatures of 200 °C with different, sometimes severe, downsides according to expert judgement.

It is summarized that emperature limits regarding the outer surface of the containers can be derived specifically for each safety concept and design of the disposal facility in a host rock. General temperature limits without reference to specific safety concepts or the particular design of the disposal facility may narrow down the possibilities for optimisation of the disposal facility and could adversely affect the site selection process in finding the best suitable site.

How to cite: Bracke, G., Hartwig-Thurat, E., Larue, J., Meleshyn, A., Weyand, T., and Kock, I.: Which Processes could define Temperature Limits on the Outer Surface of a Container in a Disposal Facility ?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3336, https://doi.org/10.5194/egusphere-egu2020-3336, 2020.

EGU2020-6079 | Displays | ERE4.2

Near field evolution of a spent fuel repository in an argillaceous rock formation and impact on radionuclide migration

Vanessa Montoya, Orlando Silva, Emilie Coene, Jorge Molinero, Renchao Lu, Haibing Shao, and Olaf Kolditz

In August 2015, the German government approved the national programme for the responsible and safe management of spent nuclear fuel (SNF) and radioactive waste proposed by the Federal Ministry for the Environment, Nature Conservation, Building and Reactor Safety (BMU). The assumption is that about ~ 1 100 storage casks (10 500 tons of heavy metal) in the form of spent fuel assemblies will be generated in nuclear power plants and will have to be disposed. However, a decision on the disposal concept for high-level waste is pending and an appropriate solution has to be developed with a balance in multiple aspects. All potential types of host rocks, clay and salt stones as well as crystalline formations are under consideration. In the decision process, evaluation of the risk of different waste management options and scenarios play an enormous role in the discussion. Coupled physical and chemical processes taking place within the engineered barrier system of a repository for high-level radioactive waste will define the radionuclide mobility/retention and the possible radiological impact. The objective of this work is to assess coupled processes occurring in the near-field of a generic repository for spent nuclear fuel in a high saline clay host rock, integrating complex geochemical processes at centimetre-scale. The scenario considers that radionuclides can be released during a period of thousands of years after full saturation of the bentonite barrier and the thermal phase.

Transport parameters and the discretization of the system, are implemented in a 2D axisymmetric geometry. The multi-barrier system is emplaced in clay and a solubility limited source term for the selected radionuclides is assumed. Kinetics and chemical equilibria reactions are simulated using parameters obtained from experiments. Additionally, porosity changes due to mineral precipitation/dissolution and feedback on the effective diffusion coefficient are taken into account. Protonation/deprotonation, ion exchange reactions and radionuclide inner-sphere sorption is considered.

Numerical simulations show, that, when the canister corrosion starts, the redox potential decreases, magnetite precipitates and H2 is formed. Furthermore, the aqueous concentration of Fe(II) increases due to the presence of magnetite. By considering binding to montmorillonite via ion exchange reactions, the bentonite acts as a sink for Fe(II). Additionally, magnetite forms a chemical barrier offering significant sorption capacity for many radionuclides. Finally, a decrease of porosity in the bentonite/canister interface leads to a further deceleration of radionuclide migration. Due to the complexity of reactive transport processes in saline environments, benchmarking of reactive transport models (RTM) is important also to build confidence in those modelling approaches. Development of RTM benchmark procedures is part of the iCROSS project (Integrity of nuclear waste repository systems - Cross-scale system understanding and analysis) funded by both the Helmholtz Association and the Federal Ministry of Education and Research (BMBF).

 

How to cite: Montoya, V., Silva, O., Coene, E., Molinero, J., Lu, R., Shao, H., and Kolditz, O.: Near field evolution of a spent fuel repository in an argillaceous rock formation and impact on radionuclide migration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6079, https://doi.org/10.5194/egusphere-egu2020-6079, 2020.

EGU2020-74 | Displays | ERE4.2

REPRO: Through Diffusion Experiment (TDE) - Diffusion and Porosity Properties of Rock Matrix in Stress Field of Repository Level

Kalle Rahkola, Antti Poteri, Lasse Koskinen, Peter Andersson, Kersti Nilsson, Johan Byegård, Marja Siitari-Kauppi, and Kerttuli Helariutta

Radionuclides usually migrate slower than the flowing water due to sorption and matrix diffusion. The performance assessment assumes that retention takes place mostly in the vicinity of the deposition holes. REPRO (REtention Properties of ROck matrix) experiments analyzed the matrix retention properties of the rock matrix under realistic conditions deep in the bedrock in ONKALO underground characterization facility at Olkiluoto, Finland. The objective was to investigate tracer transport in the rock matrix, which was representative to the near-field of the final disposal repository of the spent nuclear fuel, and to demonstrate that the assumptions made in the safety case of the deep geological spent fuel repository were in line with site evidence.

REPRO is composed of several supporting laboratory and in-situ experiments which investigate the retention properties under different experimental configurations. The first in-situ experiments were water phase diffusion experiments performed 2012-2013. Through Diffusion Experiment (TDE) studies diffusion and porosity properties of rock matrix in stress field of repository level and sorption properties of nuclides in intact rock circumstances.

The TDE experiment has been performed in three parallel drillholes drilled near to each other. Breakthrough of the radioactive tracer is monitored with on-line measurements and samplings along and perpendicular to the foliation. The non-sorbing radioactive isotope traces of HTO and 36Cl, as well as slightly sorbing 22Na and strongly sorbing 133Ba and 134Cs were used. TDE was designed to control advective flow, as it had caused problems in previous in-situ tests.

Supporting laboratory studies were performed for drillcore samples sampled from the experimental drillholes. In these laboratory experiments, i.e. porosity, permeability and diffusion coefficients of the drillcores were determined using different methods.

The TDE experiment was carried out from 2016 to 2019. A breakthrough was seen in the timeframe predicted by scoping calculations carried out. REPRO has produced data and knowledge to the safety case and the performance assessment. According to the preliminary results, values measured in the laboratory are applicable also in larger scale and in-situ conditions.

How to cite: Rahkola, K., Poteri, A., Koskinen, L., Andersson, P., Nilsson, K., Byegård, J., Siitari-Kauppi, M., and Helariutta, K.: REPRO: Through Diffusion Experiment (TDE) - Diffusion and Porosity Properties of Rock Matrix in Stress Field of Repository Level, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-74, https://doi.org/10.5194/egusphere-egu2020-74, 2020.

Sorption is one of the main processes, which determine the retention of radionuclides (RN) in a repository for nuclear waste. In a multi-barrier system, the host rock poses the ultimate barrier retarding the release of RN into the environment. Feldspars (e.g. orthoclase) are one of the main constituents of crystalline rock (e.g. granite), which is considered one potential host rock type in many countries (e.g. Finland, Sweden, Germany). In this study, the sorption of trivalent actinides (Cm, Am) and their rare earth analogues (Lu, Y, Eu, Nd, La) onto orthoclase (K‑feldspar) is investigated. For reliable predictions concerning the migration of RN, a process understanding on the molecular level of such processes is necessary. To achieve this, batch sorption experiments are combined with TRLFS and SCM.

Batch experiments were performed covering a broad range of experimental conditions (pH 4-11, oxic and anoxic conditions, [M3+] = 10-6-10-4 M, 3-50 gL-1 orthoclase (grain size: < 21 and 63-200 µm; SSA: 4.2 and 0.2 m2g-1)). Weak retardation below pH 5, followed by a strong increase between pH 5 and 7 and complete removal from solution at pH ≥ 8 was observed for all investigated metals. Cm- and Eu-TRLFS-measurements suggested the formation of an outer-sphere surface complex at lower (pH<5) and two different inner-sphere surface complexes at higher pH values (pH > 5 and pH > 7.5, respectively). Surface precipitation was observed for higher metal concentrations (10-4 M). As the investigated metals revealed a similar behavior over a broad range of conditions, a generic approach was used for the SCM to describe the system as a whole. Experimental data of different series with different metals were simultaneously fitted by coupling PHREEQC with UCODE using the same underlying speciation model. Resulting generic stability constants for the involved surface complexes will be presented.

The identification of comparable processes and their unified description with one suitable model is important to map the complexity of natural systems onto simplified geochemical models. This step is crucial for large-scale reactive transport calculations needed for a reliable safety assessment of potential repository sites, as they require enormous computing efforts.

How to cite: Brinkmann, H., Neumann, J., Britz, S., Brendler, V., Stumpf, T., and Schmidt, M.: Sorption of trivalent actinides (Cm, Am) and their rare earth analogues (Lu, Y, Eu, Nd, La) onto orthoclase: Batch experiments, Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) and Surface Complexation Modeling (SCM), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7013, https://doi.org/10.5194/egusphere-egu2020-7013, 2020.

EGU2020-4606 | Displays | ERE4.2

Comparative Study of Alternative Binders for Concrete Sealing Structures in Rock Salt

Patrick Sturm, Gregor Gluth, Janis Moye, Solen Garel, and Hans-Carsten Kühne

Alkali-activated materials (AAMs), hybrid cements (cements composed of Portland cement clinker, supplementary cementitious materials and an alkaline activator) and cements based on the principle of ‘Opus Caementicium’ (OC) potentially provide advantages over conventional cements for the use in sealing structures in rock salt, such as low heat of reaction and related thermal induced deformations (expansion and contraction) and autogenous shrinkage, all of which can lead to crack formation.
In this study several binders have been investigated by isothermal calorimetry and X-ray diffraction (XRD). Specific mix-designs of the AAMs were chosen for further investigations on the development of the mechanical strength of salt-saturated mortars, i.e. crushed rock salt was used as aggregates, under different conditions (23 °C/50 % r.H. and 40 °C/35 % r.H.) and compared to a ‘low-pH’-cement-based salt-saturated reference mortar.
After a reaction time of 7 days the heat of reaction of the hybrid cements was always lower than 70 % of that of an ordinary Portland cement (OPC), while the heat of reaction of the AAM and the OC was always lower than 20 %. For the hybrid cements Na2SO4 accelerated the early reaction of the Portland clinker, while Na2CO3 appeared to decrease the reaction and led to a shift of the second hydration peak (likely related to slag reaction) to later hydration times. Besides minor peaks in the heat flow after 4 days, the AAM and OC provided a rather continuous heat release over the considered reaction time.
The AAMs showed no signs of major crystalline reaction products; only traces of carbonates, alumina or zeolites were identified after 28 days. For the hybrid cements, semicrystalline C-A-S-H, portlandite and hydrotalcite were present in all samples as hydration products. Furthermore, in these systems the use of Na2SO4 lead to the formation of ettringite (AFt-phase), while the use of Na2CO3 lead to the formation of hemicarbonate (AFm-phase).
Compared to the ‘low-pH’-cement-based mortar, the AAM-based mortars had lower mechanical strength after 28 days. With increasing curing time the differences decreased. Increasing the temperature and decreasing the air humidity led to an acceleration of the strength development at early ages, but also to a decrease of the final strength for specific AAM-based formulations, suggesting the introduction of microcracks due to drying shrinkage. The exception was the two-part AAM-formulation, which provided the highest final strength in the considered period (91 days) independent of the storing conditions.

How to cite: Sturm, P., Gluth, G., Moye, J., Garel, S., and Kühne, H.-C.: Comparative Study of Alternative Binders for Concrete Sealing Structures in Rock Salt, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4606, https://doi.org/10.5194/egusphere-egu2020-4606, 2020.

EGU2020-12948 | Displays | ERE4.2

Investigations on the permeability of MgO concrete with 5-1-8 phase at the GV2-drift-sealing in the Teutschenthal mine

Jennifer Arendt, Wolfram Kudla, Thomas Wilsnack, Till Popp, and Daniela Freyer

For underground storage facilities and future HAW repositories, a secure closure is indispensable. Within the scope of two consecutive research projects, three closure elements were installed in large-scale tests at the Teutschenthal mine in the Carnallitit Mountains between 2006 and 2008. Special mention should be made here of the large-scale test 2 (“GV2”), which was produced from MgO concrete with the 5-1-8 binder phase. This structure was made using the dry-mix shotcrete procedure. The low temperature development during the setting of the shotcrete was very advantageous. The 10.25 m long structure, with a height and width of 3.55 m each, consists of 104 concreting sections with an average layer thickness of 9.9 cm. It was of interest whether the concreting section boundaries (“BAG”) influence the permeability (negatively). The structure is equipped with pressure transmitters and TDR sensors in three measuring levels. After completion of the structure and injections in the contact area, the integral system permeability was 2*10‑16 m². Liquid pressurization via pressure chamber was carried out on the test structure after a maturing period of about 10 years. After 8 years, the permeability with gas and with solution was determined in boreholes and on drill cores, especially with regard to the development over time. The determined in-situ gas permeability is on average 2.7*10‑19 m², on compact concrete (without BAGs) on average 2.0*10-20 m². Test areas containing BAGs showed a higher permeability of maximum three orders of magnitude in some measurements. The solution permeability was determined both with a saturated NaCl solution and with a NaCl-saturated solution containing MgCl2 and is between 1.0*10‑20 m² and 9.0*10‑20 m², whereby this decreases by half a power of ten over the measurement period of 600 days. In further integral injection tests in 4.5 m and 4.8 m long boreholes, a significant decrease in permeability over time was also observed. From an initial 2*10‑15 m² and 4*10‑16 m², respectively, the integral permeability decreased to <10‑19 m² over a measuring period of 2.5 years. The reason for this decrease is the reduction of pore space due to the recrystallization of MgO and the transformation of the metastable 5-1-8 phase to the long-term stable 3-1-8 phase due to the increase in volume that takes place when the solution is added. Potential weak points or defects at the technically determined concrete section boundaries, therefore, do not represent weak zones in the structure in the long term due to this self-healing effect.

This paper reports on the large-scale experiment GV2 made of MgO concrete with 5-1-8 phase and the comprehensive permeability and strength investigations in drillings and on drill cores. The test results are the precondition for a modeling of the long-term behaviour of MgO-concrete.

How to cite: Arendt, J., Kudla, W., Wilsnack, T., Popp, T., and Freyer, D.: Investigations on the permeability of MgO concrete with 5-1-8 phase at the GV2-drift-sealing in the Teutschenthal mine, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12948, https://doi.org/10.5194/egusphere-egu2020-12948, 2020.

EGU2020-20326 | Displays | ERE4.2

Evaluation of crystalline rock pore water geochemistry in DGR conditions

Václava Havlová, Milan Zuna, Anna Pecková, and Filip Jankovský

Geochemistry of groundwater within the host rock is one of the most crucial boundary conditions for radionuclide speciation and migration.

The typical porosity of crystalline rock is less 0,5 wt%. In addition to the circulation of groundwater in the cracks, different types of fluids may be present in the pore space. Total porosity εT - corresponds to the volume of rock not filled with mineral grains. It is often defined by the relation: εT = εF + εD + εR, where εF stands for effective porosity (the dominant fluid transport is advective flow). εD represents diffusive porosity (the predominant transport in water-filled pores is diffusion) and εR represents residual porosity (discontinuous pores in which no transport takes place), in which solutions may also be present in closed inclusions.

Most of the solutions contained in the pore space, the "pore fluid of the rock matrix", cannot be collected using conventional groundwater sampling techniques. Only limited number of techniques has been reported, e.g. Smellie et al., (2003); Waber and Smellie (2008) and Eichinger et al. (2008).

Therefore, determination of pore water chemistry in crystalline rock from underground laboratory Bukov (SÚRAO) in at least 500 m depth was in focus, testing different laboratory and in-situ techniques. Fresh crystalline rock samples from the 12th (-550 m) and 24th (-1 000 m) horizon of Bukov URL were used for the laboratory experiments. In-situ sampler was installed at undisturbed section of the borehole at URL Bukov.

Firstly, leaching experiments, inspired by methods mentioned above were performed.

Secondly, high pressure techniques were used in order to extract pore water from the rock samples.

Finally, in-situ extraction of rock fluids, using a sampling packer system, installed into the undisturbed rock section, was applied.

Paralelly, geochemical modelling, using PHREEQC code, considering long-term interaction of main rock constituting minerals with solution in pores, was ongoing.

The results of in-situ sampling, lab leaching and modelling indicated that the determination of the pore water composition of crystalline rocks is still an open issue, since only about 1.5 ml of groundwater was present in approximately 20 cm of drill core (porosity below 0.5%).

Its composition will be significantly influenced by the equilibration of the solutions, entering pores, with the main and minor rock components (e.g. sulphites). The composition will most probably move towards the Na-HCO3-Cl type with increasing chloride component with increasing depth. Here close communication with depth specific groundwater can be found. However, chlorine source within quartz – plagioclase – biotite – amphibolites rock type is not clear. Geochemical modelling showed that Cl- source other than rock forming minerals might have an influence, either residual solutions or fluid inclusions (containing NaCl according to the analyses).

References:

Smellie J. et al.. (2003): Technical Report, SKB, TR-03-18.

Waber, H., Smellie (2008):  Applied Geochemistry 23, 1834-1861.

Eichinger F. et al. (2008): Project Report, Nagra, NPB 08-16.

Eichinger F. at al. (2006): Posiva Working Report 2006-103.

Acknowledgements

The work described herein was funded by SÚRAO within Deep Horizons project (SO2017-023).

How to cite: Havlová, V., Zuna, M., Pecková, A., and Jankovský, F.: Evaluation of crystalline rock pore water geochemistry in DGR conditions , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20326, https://doi.org/10.5194/egusphere-egu2020-20326, 2020.

EGU2020-21509 | Displays | ERE4.2

3D hydrogeological modeling of Deep Geological Disposal in the Nizhnekansky Rock massif

Georgii Neuvazhaev, Alexander Rastorguev, Oleg Morozov, Ivan Kapyrin, and Fedor Grigorev

Russian Federation has a selected site for Deep Geological Disposal in the Nizhnekansky massif (Krasnoyarsk territory). The current work is devoted to justification of its suitability. One of the main parts of the safety case of is the prediction of radionuclides migration in the environment which requires development and application of groundwater flow and transport models. This work presents the evolution of the hydrogeological model.

The granitoid rock of Nizhnekansky massif is complicated by presence of such geological structural elements as dykes, faults and crushing zones which influence significantly permeability features. Currently all available geological data are consolidated with the use of the MICROMINE program into a structural geological model. The three-dimensional model of the distribution of the main structural elements in the area of the DGD site is more detailed. The corresponding dykes appear to have a north trend and a steep fall (about 70 ° east).

Using the geometry of structural elements one can assess their role in the structure of groundwater flow on the basis of profile model. Verification of the model was carried out on the basis of measured hydraulic heads.

The preliminary calculations showed that including into the model additional structural elements (to a greater extent dykes and crushing zones) leads to a better matching between observed and model heads. This implies the need to take into account the structural elements  more accurately. The migration of a conservative tracer was calculated as well using the developed flow model.

Moreover, the heterogeneity near the Deep Geological Disposal is three-dimensional in nature and it is impossible to implement it accurately in a two-dimensional setting without approximations. This requires three-dimensional modeling, such 3D numerical flow and transport models are developed using the GeRa code.

How to cite: Neuvazhaev, G., Rastorguev, A., Morozov, O., Kapyrin, I., and Grigorev, F.: 3D hydrogeological modeling of Deep Geological Disposal in the Nizhnekansky Rock massif, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21509, https://doi.org/10.5194/egusphere-egu2020-21509, 2020.

In some countries, low carbon steel has been considered as the candidate material of the disposal container for high-level radioactive wastes (HLWs) due to its excellent anti-irradiation, high strength, low cost and fine processing performance. However, during the long-term geological disposal, the steel disposal container will suffer from the threat of corrosion damage under the coupled THMC conditions.

This work focused on the corrosion behavior of low carbon steel under different water conditions in compacted bentonite of China-Mock-Up by in situ electrochemical impedance spectroscopy (EIS) with the infiltration of groundwater from outside to inside. Based on the EIS results, the corresponding equivalent circuit models were proposed to interpret the evolution of electrochemical characteristics of low carbon steel with the increase of water content in compacted bentonite. In the initial stage of EIS measurement, water in bentonite around the electrochemical sensors from outside to inside was hygroscopic water and chemical bonding water successively. With the running of China-Mock-Up, water in outer bentonite transformed from hygroscopic water to free water. Meanwhile, the water in the inner bentonite blocks transformed from chemical bonding water to hygroscopic water, which caused a slight corrosion of low carbon steel. After China-Mock-Up running for 1202 days, the instantaneous corrosion rate of low carbon steel located in the inner bentonite blocks was just 0.002 mm/a. While in the outside bentonite blocks, the corrosion rate reached to 0.58 mm/a after 1155 days, indicating that the free water could cause a serious corrosion of low carbon steel.

How to cite: Wei, X., Liu, Y., and Dong, J.: Corrosion behavior of low carbon steel under different water conditions in compacted bentonite of China-Mock-Up, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6356, https://doi.org/10.5194/egusphere-egu2020-6356, 2020.

EGU2020-1578 | Displays | ERE4.2

Geochemically coupled 2D models reproduce the formation of transition zones within potash seams

Svenja Steding, Thomas Kempka, Axel Zirkler, and Michael Kühn

In Germany, salt deposits play an important role as industrial raw material as well as sites for energy storage. However, in geological fault zones, the contact with migrating groundwater can lead to the formation of geogenic caverns that are filled with gas and brine. These brine occurrences belong to the most significant risks in salt mining as they can cause mine flooding and land subsidence. Especially within highly soluble potash seams, the interactions between brine and salt rock result in cavernous structures surrounded by moisture penetration zones (hereinafter referred to as transition zones). In order to facilitate an early detection and a safe long-term retention of geogenic caverns, the temporal and spatial development of these transition zones was simulated.

In a first step, the software PHREEQC (Parkhurst & Appelo, 2013) and a polytherm dataset for the hexary system Na-K-Mg-Cl-SO4-Ca-H2O from THEREDA were used to investigate the dissolution behavior of different potash salts. A titration model based on thermodynamic equilibrium showed that the components within a potash seam are only partly converted into secondary minerals. Brine composition and precipitations mainly depend on the ratio between kieserite and sylvite and the dissolution process only stops if water, kieserite or sylvite is fully depleted. As a consequence, 1 kg of brine can influence several tens of kilograms of potash salt. A 1D model in PHREEQC implied that the transition zone between a cavernous structure and the unaffected rock can be divided into different mineralogical regions, containing secondary minerals like glaserite, leonite or kainite besides halite. A comparison with measured data from a natural brine occurrence validates the model results. However, these models do not include temporal or spacial scaling.

The titration model in PHREEQC was then used as a basis for the coupling of chemistry and hydraulics which is done in Python. Transport processes free and forced convection as well as diffusion are taken into account. A 2D model of the potash seam was built considering the stratification of the rock as well as changing permeabilities due to geological fault zones and dissolution and precipitation. Cavern and transition zone are assumed to be porous media which coincides with field measurements from K+S. In the area of the dissolution front, the amount of dry potash salt that is made available for chemical reactions is controlled by a dissolution rate. Apart from that, thermodynamic equilibrium is assumed within the transition zone but a temporal scaling is still given based on the exchange rate. Besides sensitivity analyses, several scenario analyses for varying initial and boundary conditions have been done. The results are compared to a natural transition zone in a german mine and provide important insights into the long-term development of natural cavern systems within potash seams.

References:

Parkhurst, D. L., Appelo, C. A. J. (2013): Description of input and examples for PHREEQC version 3 - a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. US Geological Survey Techniques and Methods, 6 (A43), 497 p.

How to cite: Steding, S., Kempka, T., Zirkler, A., and Kühn, M.: Geochemically coupled 2D models reproduce the formation of transition zones within potash seams, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1578, https://doi.org/10.5194/egusphere-egu2020-1578, 2020.

EGU2020-5705 | Displays | ERE4.2

Reservoir Response to Heat Generating Nuclear Waste Disposal in Bedded Salt

Richard Jayne and Kristopher Kuhlman

The disposal of heat generating nuclear waste is increasingly becoming a concern for several countries worldwide. This issue is of particular concern for the United States because of the 364,000 m3 of heat-generating nuclear waste currently in temporary storage. Numerous concepts for the disposal of heat generating nuclear waste have been investigated internationally, such as, mined repositories in crystalline, argillite, and salt formations, and deep borehole disposal. Currently, salt formations are being investigated as candidate disposal host rocks for heat-generating nuclear waste in the United States, Germany, the Netherlands, and the United Kingdom. Salt formations may be an ideal host media due to salt’s extremely low permeability, high thermal conductivity, and self-healing capability. Salt lacks circulating groundwater, but it is not dry. Brine availability in salt has multiple implications for the safety and design of a nuclear waste storage facility. Brine transport is a potential off-site radionuclide transport vector, brine leads to corrosion of metallic and glass waste forms and waste packages, chloride in brine can reduce criticality concerns, and accumulated brine can provide back-pressure that resists long-term creep closure of porosity associated with mining the repository. In order to improve understanding of brine migration in heated salt, borehole heater experiments are being conducted at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. The salt heater test collaboration aims to collect data to gain a better understanding of brine availability, transport, and thermal evolution of salt in response to heating up to 140 °C. Due to the complex nature and coupled processes that take place within bedded salt, this study will utilize 1D, 2D, and 3D numerical simulations of the salt heater test to deconvolve the parametric controls on brine availability and migration. The purpose of this study is two-fold, in addition to understanding the hydrogeology of salt formations, we utilize two different subsurface flow codes in a code comparison study, TOUGH and PFLOTRAN. Preliminary results from this study illustrate the importance of understanding the host rock properties and the initial/boundary conditions of the salt and multiphase fluid flow near the excavation site.

 

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

How to cite: Jayne, R. and Kuhlman, K.: Reservoir Response to Heat Generating Nuclear Waste Disposal in Bedded Salt, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5705, https://doi.org/10.5194/egusphere-egu2020-5705, 2020.

EGU2020-9314 | Displays | ERE4.2

In-situ Experiment on the Influence of Humidity on the Cyclic and Long-Term Deformation Behavior (CD-A) of the Opalinus Clay at the Mont Terri Rock Laboratory, Switzerland: Excavation of the Twin Niches, First Measurements, Simulations and Analysis

Jobst Maßmann, Gesa Ziefle, Stephan Costabel, Markus Furche, Bastian Graupner, Jürgen Hesser, David Jaeggi, Franz Königer, Karsten Rink, Rainer Schuhmann, Bernhard Vowinckel, and Klaus Wieczorek

Claystone is characterized by a complex, highly coupled hydraulic-mechanical behavior. The physical understanding of the related effects is of great importance concerning the stability during the construction phase as well as for the safety assessment of the integrity of a potential repository for high-level nuclear waste. The rock laboratory Mont Terri, Switzerland, provides the unique possibility to conduct in-situ experiments in the Opalinus Clay for a broad international community. The experiment on the influence of humidity on the cyclic and long-term deformation behavior (CD-A experiment) is conducted in the new part of the rock laboratory, which has been finalized in 2019.

To compare the coupled hydraulic-mechanical effects under different conditions, two parallel oriented niches, called twins, have been excavated in autumn 2019. The twins have a length of 11 m and a diameter of 2.3 m and no shotcrete support. The first twin remains under “natural conditions”. Here, the atmospheric conditions are characterized by a seasonal change in air humidity and temperature. This leads to a desaturation of the claystone around the niche. The second twin is locked. In this area, the air conditions imply a high humidity and the desaturation of the claystone will be avoided as much as possible.

In both twins, a geological characterization of drill cores and of rocks exposed in the niches have been carried out. Furthermore, a long-term measurement program of the related parameters has been launched. It includes measurements of the air humidity, the temperature, the deformation (extensometer), the convergence of the niches, the pore water pressure (piezometer) and the water content (Taupe). Additionally, periodic measurements of the permeability, electrical resistivity (ERT), and nuclear magnetic resonance (NMR) on the niche walls as well as petrophysical analyses of drilled cores are planned. Seismic borehole measurements will also be carried out. The measuring program will be accompanied by the numerical simulation of the coupled hydraulic-mechanical effects in the vicinity of the niches. The comparison of the measurements with simulation results considering different model approaches should support the identification of significant physical effects of the complex coupled material behavior.

This contribution will focus on the observations during the excavation of the twin niches and analysis of the first measured data as well as numerical investigations carried out with OpenGeoSys.

How to cite: Maßmann, J., Ziefle, G., Costabel, S., Furche, M., Graupner, B., Hesser, J., Jaeggi, D., Königer, F., Rink, K., Schuhmann, R., Vowinckel, B., and Wieczorek, K.: In-situ Experiment on the Influence of Humidity on the Cyclic and Long-Term Deformation Behavior (CD-A) of the Opalinus Clay at the Mont Terri Rock Laboratory, Switzerland: Excavation of the Twin Niches, First Measurements, Simulations and Analysis , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9314, https://doi.org/10.5194/egusphere-egu2020-9314, 2020.

EGU2020-9654 | Displays | ERE4.2

Microbial activity in nuclear waste repository systems

Johannes Raff, Margarita Lopez-Fernandez, Stephan Hilpmann, Sindy Kluge, Robin Steudtner, and Andrea Cherkouk

A multi-barrier system in which the radioactive waste is encapsulated in metal containers surrounded by a geotechnical barrier (e.g. compacted bentonite) deep underground in a stable geological formation is one of the internationally accepted options for the disposal of highly radioactive waste. Bentonites have good properties such as high swelling capacity and low hydraulic conductivity, which makes them favorable as backfilling material. However, indigenous microorganisms may affect these properties. Bentonite samples were collected from the Full-scale Engineered Barrier Experiment (FEBEX) - Dismantling Project [1] at the Grimsel Test Site (Switzerland) to study their microbial diversity. For that, total DNA was extracted directly from the cores and from enrichments of sulfate- and iron-reducing microorganisms as well as microorganisms were isolated from those enrichments. The microbial communities of the bentonites, the enrichments, as well as the isolates were analyzed by 16S rRNA gene sequencing. The results showed that Actinobacteria and Alphaproteobacteria dominated the FEBEX bentonite microbial population, while the dominant phylum in both enrichments was Firmicutes: concretely, Bacilli and Clostridia classes. In addition, bacteria from the genera Desulfitobacterium, Desulfosporosinus and Clostridium were isolated from the enrichments. Desulfosporosinus hippei DSM 8344 as a phylogenetic close relative was selected to study its interactions with uranium and especially its potential to reduce U(VI) to U(IV). This study revealed that microorganisms are present in bentonite samples after a long-term continuous heating. Sulfate- and iron-reducing microbes were enriched by using favorable conditions in specific media and the potential of the sulfate-reducing microorganisms on the reduction of uranium was verified. Therefore, it is important to characterize the microbial population of the bentonite, because microbes might compromise the safety of the deep geological repository of highly radioactive waste.

[1]http://www.grimsel.com/gts-phase-vi/febex-dp/febex-dp-introduction

How to cite: Raff, J., Lopez-Fernandez, M., Hilpmann, S., Kluge, S., Steudtner, R., and Cherkouk, A.: Microbial activity in nuclear waste repository systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9654, https://doi.org/10.5194/egusphere-egu2020-9654, 2020.

In this study, we considered different the wind speeds affects the thermal performance when the dry storage cask for spent nuclear fuel , which used NAC- MAGNASTOR cask of system, and placed outdoors. We Ddiscuss the dry storage cask for spent nuclear fuel cooling by the thermal buoyancy ventilation of cask. Firstly, Compare the experimental data of low-speed wind tunnel experiments with the result of from a commercial software PHOENICS CFD (Computational Fluid Dynamics) for heat flow analysis, and confirm the reliability of the CFD simulation results of the software. Then we used the software to simulate higher wind speeds to understand the thermal performance of the cask for spent nuclear fuel by various wind speeds. With external wind speed is was more much faster, channel airflow of the cask hads increased, especially upper channel airflow of the cask and near steel cylindrical. The temperature of the windward side of the cask hads also been significantly reduced, The lee side hads a slower wind speed and a smaller temperature drop, and generates an eddy below the lee side, which helpeds to dissipate .heat,. However, as the wind speed gradually increases, the lee side changed to a downdraft, and the temperature drop was also slowed down. It is noticeable that the situation may occur when a typhoon comes.

How to cite: Cheng, L. and Lai, C.-M.: The effect of the cooling on a dry storage cask for spent nuclear fuel by different wind speed, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13709, https://doi.org/10.5194/egusphere-egu2020-13709, 2020.

EGU2020-16928 | Displays | ERE4.2

The SpannEnD Project - Numerical modelling of the 3D stress state of Germany

Steffen Ahlers, Luisa Röckel, Andreas Henk, Karsten Reiter, Tobias Hergert, Birgit Müller, Frank Schilling, Oliver Heidbach, Sophia Morawietz, Magdalena Scheck-Wenderoth, and Denis Anikiev

One important criterion for the characterization of a potential nuclear waste repository is the crustal stress field. However, stress data are sparse and usually incomplete regarding the six independent components of the stress tensor. The World Stress Map (WSM) is a valuable compilation of stress data, but it does not include information about stress magnitudes as only the orientation of the maximum horizontal stress (SHmax) is provided. To receive a comprehensive and continuous 3D description of the stress field in a particular area, geomechanical-numerical modelling is required. Key objectives of the SpannEnD project (Spannungsmodell Endlagerung Deutschland) is to provide such a model for Germany and to develop methods for robust stress predictions at the local scale.

The SpannEnD model is based on finite element techniques and comprises a 3D lithosphere-scale structural model of Germany. The lateral extent of the model covers a pentagon-shaped area of Central Europe with dimensions of 1000 x 1250 km². The model has been chosen significantly larger than Germany to reduce boundary effects in the study area. Furthermore, on the base of the observed stress orientation pattern, the boundaries have been defined parallel or perpendicular to the known orientation of SHmax to simplify the definition of the boundary conditions. The vertical extent of the model is from the surface to a depth of 100 km, incorporating several sedimentary layers, several basement units and the Mohorovičić discontinuity. The mesh is laterally homogenous with a resolution of about 4 km and vertically inhomogeneous with a decreasing resolution with increasing depth, to provide the finest mesh in the layers of the greatest interest, near the surface. These units also provide the most stress data measurements to calibrate the model. Furthermore, a selected number of important faults is implemented in the model. This structural model is discretized into about 4 million elements. For the calibration of the model we use a new compilation of stress magnitude data. We present the workflow, the model geometry, and some first results.

How to cite: Ahlers, S., Röckel, L., Henk, A., Reiter, K., Hergert, T., Müller, B., Schilling, F., Heidbach, O., Morawietz, S., Scheck-Wenderoth, M., and Anikiev, D.: The SpannEnD Project - Numerical modelling of the 3D stress state of Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16928, https://doi.org/10.5194/egusphere-egu2020-16928, 2020.

EGU2020-14981 | Displays | ERE4.2

Sensitivity analysis for numerical modeling of a generic repository for nuclear waste in bedded salt

Wenting Liu, Ralf Eickemeier, and Sandra Fahland

Numerical models of a generic repository for nuclear waste were created to analyze the long-term barrier integrity of bedded salt formations. This study focuses on sensitivity analysis and validation for numerical simulation by using 2D models. Under consideration of thermal loading caused by the disposal of heat generating nuclear waste, thermal and thermomechanical coupled calculations were performed using FEM code JIFE (Faust et al. 2016). Thermal analyses were conducted to investigate the influence of mesh density on the temperature results in both near and far field of disposal area. Thermomechanical coupled calculations were carried out to evaluate boundary influence of different model dimension on the results of temperature and vertical displacement. Furthermore, since the overburden are assumed to be elastic, variation of Young’s modulus shows sensitivity of overburden stiffness in thermomechanical coupled calculations of the generic model for bedded salt. The calculated stress and deformation were compared to investigate the influence of overburden stiffness on the results of geomechanical assessment of the salt barrier integrity. The observation of this study gives a better understanding of how to establish a 2D or 3D model in bedded salt formation for barrier integrity analysis.

How to cite: Liu, W., Eickemeier, R., and Fahland, S.: Sensitivity analysis for numerical modeling of a generic repository for nuclear waste in bedded salt, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14981, https://doi.org/10.5194/egusphere-egu2020-14981, 2020.

The multi-barrier concept of HLW storage in geological formations relies on the thermo-, hydro-, mechanical (THM) and chemical properties of the potential host rock. In claystone, these properties are strongly influenced by its mineralogical composition and their spatial distribution.

As part of the first phase of the BASTION project, BGR carried out investigations in two areas. The geological part focused on the structural-lithological composition of various claystone formations. The numerical part investigated methods to integrate the drillcore-scale properties into formation-scale numerical THM models with the aim of being able to perform generic model studies at this scale. A major challenge in the first phase of the project was the conversion and transfer of data collected from structural and mineralogical studies to the input parameters required in the THM models for the simulation of generic site studies and future assessment cases.

In the current contribution, a further step is taken towards this purpose while retaining the focus on the determination of thermal parameters of claystone. The classification of the geological sub-units as facies types in claystone has been extended with the introduction of the sub-facies concept, thus allowing a finer resolution in the classification within each facies type. The introduction and standardization of this concept for claystone are foreseen to allow a more precise choice of samples for the experimental determination of (thermal) parameters. This workflow is presented as a proof-of-concept and is utilized in a simplified simulation to evaluate its benefits. Extension of the concept to other input parameters of numerical THM models will be touched upon. The presented concept contributes towards the continuing effort to integrate data from drillcore-scale measurements in formation-scale simulations.

How to cite: Kumar, V., Kneuker, T., and Maßmann, J.: Transferring geo-/mineralogical information to THM simulations of HLW storage in claystone formations (BASTION II), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17898, https://doi.org/10.5194/egusphere-egu2020-17898, 2020.

EGU2020-17712 | Displays | ERE4.2

Impacts of changing conditions on far-field radionuclide evolution: background and goals of a newly funded DFG-RFBR project.

Fabien Magri, Thomas Nagel, Axel Liebscher, and Victor Malkovsky

To date, the most secure, technically feasible and internationally accepted solution for the safe management of Radioactive Waste (RW) is burial in deep host rock units, also referred to as disposal in a deep geological repository (DGR). For this purpose, it is mandatory to select a site in a hydrogeological setting which provides sufficiently safe natural conditions for waste isolation from groundwater flow over long time periods (up to 1 Ma).

However, over such a long time period, external factors (e.g. climate change) and intrinsic basin features (e.g. tectonics), here referred to as changing conditions, will impact the hydrological (H), thermal (T), mechanical (M) and chemical (C) state of the entire system. Therefore, it is crucial to better understand the impacts of changing conditions on far-field radionuclide mobilization and behavior in order to select the most suitable DGR for RW disposal.

Multiphysics simulators offer powerful tools that couple groundwater flow (H), transport of heat (T), as well as geochemical reactions (C) in a deforming solid framework (M). These coupled THM-C numerical models can provide evaluations for performance and safety assessment of a DGR at different scales. However, a limited number of studies so far addressed the far-field evolution of radionuclides under the changing conditions listed above.

The newly funded German Science Foundation (DFG) and the Russian Foundation for Basic Research (RFBR) project “INFRA” (NA1528/2-1 and MA4450/5-1; 2020-2022) aims to investigate the impacts of (i) glaciation, (ii) permafrost and (iii) tectonic events on the coupled boundaries that control large-scale groundwater flow near hypothetical waste repositories. For this purpose, the open source simulator OpenGeoSys [1,2] will be applied using available data from selected areas of the Yeniseisky Site in Russia [3].

Though the context of this study is related to RW issues, the outcomes of INFRA will be of interest for any field of geosciences that deals with large-scale simulations of coupled processes under transient boundary conditions.

 

[1] Kolditz, O., Bauer, S., Bilke, L., Böttcher, N., Delfs, J. O., Fischer, T., … Zehner, B. (2012). OpenGeoSys: an open-source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media. Environmental Earth Sciences, 67(2), 589–599. https://doi.org/10.1007/s12665-012-1546-x

[2] Bilke, L., Flemisch, B., Kalbacher, T., Kolditz, O., Helmig, R., & Nagel, T. (2019). Development of Open-Source Porous Media Simulators: Principles and Experiences. Transport in Porous Media, 130(1), 337–361. https://doi.org/10.1007/s11242-019-01310-1.

[3] Laverov, N., Yudintsev, S., Kochkin, B., Malkovsky V. (2016). The Russian Strategy of using Crystalline Rock as a Repository for Nuclear Waste. Elements, 12(4), 253–256. https://doi: 10.2113/gselements.12.4.253  

How to cite: Magri, F., Nagel, T., Liebscher, A., and Malkovsky, V.: Impacts of changing conditions on far-field radionuclide evolution: background and goals of a newly funded DFG-RFBR project., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17712, https://doi.org/10.5194/egusphere-egu2020-17712, 2020.

This study aims at investigating the hydraulic and thermal properties which are important for buffer materials to be used for geological disposal of high-level radioactive wastes. MX-80 bentonite and Kunigel V1 bentonite, originated from Wyoming USA and Japan, respectively, were used in the experimental program. The characteristics of these 2 bentonites, including soil-water characteristic curve, swelling pressure, hydraulic conductivity, and thermal conductivity were determined in the laboratory. And these data are applied in the simulation of the resaturation processes of buffer material in a deposition hole, such that a comparison can be made on the thermo-hydro-mechanical coupling effects of the buffer material can be evaluated. It is found that the two bentonites do not behave very differently in terms of the moisture distribution and heat transfer characteristics with the same boundary conditions assumed. 

How to cite: Huang, W.-H.: Experimental study on the thermo- and hydro- properties of two bentonites as buffer materials, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19178, https://doi.org/10.5194/egusphere-egu2020-19178, 2020.

EGU2020-19441 | Displays | ERE4.2

Experimental assessment of interaction between boric acid enriched in boron-10 and cementitious matrix

Mojtaba Rostamiparsa, Zsuzsanna Szabó-Krausz, Margit Fábián, György Falus, Csaba Szabó, and Péter Völgyesi

After some decades in applying boric acid with natural isotopic abundance (natural boric acid, NBA) solution as a neutron absorber, some nuclear facilities have started to use boric acid enriched in B-10 (enriched boric acid, EBA) to increase the control ability and parallelly, decrease the amount of liquid waste. Meanwhile, the stabilization condition of EBA in the cementitious matrix and durability of the waste form in disposal facilities have not been assessed or at least have not been reported yet. However, high relative mass difference between the two stable isotopes of boron (B-10 and B-11) implies a different leachability index for cementitious matrix prepared with NBA and EBA wastes.

In this study, the leachability (ASTM C1308-08 standard, 2017) of boron isotopes from cementitious matrix and its geochemical background will be assessed using ICP-OES, XRD, SEM-EDX and Raman-spectroscopy. The effects of parameters such as temperature, water to cement ratio (w/c), boric acid concentration and shape of the waste form will be studied. Geochemical modeling of the experiments will be done via PHREEQC software, which should support our understanding of the different geochemical behavior of NBA and EBA.

Based on the theoretical knowledge, a significant increase in leachability of boron from the cementitious matrix is expected when EBA is used instead of NBA because of the geochemical behavior of the two stable isotopes. Increase in leachability is expected when temperature and w/c increased, whereas the leachability will decrease when the normal cylindrical shape of samples are changed to spherical shape.

References:

  • M. Saleh and H. A. Shatta; 2013; Immobilization of Simulated Borate Radioactive Waste Solution in Cement-Poly(methylmethacrylate) Composite:Mechanical and Chemical Characterizations; Journal of Nuclear Chemistry; Article ID 749505.
  • Lucile Dezerald, Jorge J. Kohanoff, Alfredo A. Correa, Alfredo Caro, Roland J.-M. Pellenq, Franz J. Ulm and Andrés Saúl; 2015; Cement as a Waste Form for Nuclear Fission Products: The Case of 90Sr and Its Daughters; Journal of Environmental science and technology; 49; 13676−13683.
  • ASTM C1308 - 08(2017); Standard Test Method for Accelerated Leach Test for Diffusive Releases from Solidified Waste and a Computer Program to Model Diffusive, Fractional Leaching from Cylindrical Waste Forms; west conshohocken, PA 19428, United state
  • IAEA; 1996; Processing of nuclear power plant waste streams containing boric acid; IAEA-TECDOC-911, ISSN 1011-4289; Vienna, Austria.

How to cite: Rostamiparsa, M., Szabó-Krausz, Z., Fábián, M., Falus, G., Szabó, C., and Völgyesi, P.: Experimental assessment of interaction between boric acid enriched in boron-10 and cementitious matrix , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19441, https://doi.org/10.5194/egusphere-egu2020-19441, 2020.

EGU2020-20210 | Displays | ERE4.2

Criteria of fault selection for geomechanical models

Luisa Röckel, Steffen Ahlers, Sophia Morawietz, Karsten Reiter, and Birgit Müller and the The SpannEnD Team

Numerical modelling is an important method in the improvement of the understanding of a variety of geological processes such as the reactivation of faults and seismicity, orogeny or volcanism. Furthermore, it can be crucial for geotechnical activities such as geothermal use of the underground, oil and gas production or the use of dams. Geomechanical models enable stress predictions even in areas without stress data and can therefore greatly contribute to the long-term safety and productivity of underground activities.

As computational power is limited the geology of geomechanical models often needs to be simplified, especially for larger scale models. This is true not only for the resolution of the implemented stratigraphy but also for the implementation of faults as they severely increase the amount of required elements and influence the model stability. Furthermore, the implementation of faults often leads to artifacts and can therefore reduce the accuracy of the model results. Due to these limitations it is frequently necessary to distinguish between faults that are crucial for the model as they influence the stresses in magnitude and orientation on a large scale and faults that will only influence the model on a local scale and may therefore be neglected on a regional perspective. The impact of faults on a geomechanical model depends on various different factors such as geometry and mechanical properties of the fault itself, the tectonic regime or the scale of the model. As the relevance of a fault for a geomechanical model is not necessarily identical to its relevance in other geoscientific fields it can be challenging to identify relevant faults.

The SpannEnD project focuses on the generation of a 3-D geomechanical model of Germany and adjacent areas in the context of the disposal of nuclear waste in order to predict the tectonic stresses in areas without stress data. There is a multitude of faults known in the modelling area but due to their sheer amount not all faults can be incorporated. Criteria have to be found that drastically reduce the number of faults while keeping the change in the geomechanical stress pattern to a minimum. We will present different criteria that can be used for the fault selection which have being worked out in the framework of the SpannEnD project.

How to cite: Röckel, L., Ahlers, S., Morawietz, S., Reiter, K., and Müller, B. and the The SpannEnD Team: Criteria of fault selection for geomechanical models , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20210, https://doi.org/10.5194/egusphere-egu2020-20210, 2020.

The Federal Republic of Germany has decided to dispose its high-level radioactive waste in deep geological formations. Three types of host rock are considered: rock salt, clay rock and crystalline rock. The Site Selection Act (StandAG1), which came into effect on the 16th of May 2017, defines the successive steps of the repository siting process, which has to ensure the best possible safety conditions for a period of one million years. Based on precaution considerations, the StandAG (§27 (4) StandAG) sets a preliminary temperature limit of 100°C at the outer surface of a repository container for the preliminary safety assessment.

This contribution provides an overview about the state of the scientific and technical knowledge on the limiting temperatures in the repository site selection process of Germany. It also illustrates the different treatments of the definition of temperature limits within other European siting processes. The findings highlight that, in Europe, the proposed criteria which consider temperature at the outer surface of a repository container get more and more into focus of research and discussion especially for the three different types of host rocks.

After presenting the national regulatory frameworks, this contribution summarizes how the European countries address the different temperature related issues for their site selection, their repository concepts and how in turn these all can influence the German safety case strategy for the German site selection. Not at least, links to site selection criteria in other countries (e.g. USA, Japan, Russia) are provided.

Reference

1  StandAG: Standortauswahlgesetz vom 5. Mai 2017 (BGBl. I S. 1074), das zuletzt durch Artikel 2 Absatz 16 des Gesetzes vom 20. Juli 2017 (BGBl. I S. 2808) geändert worden ist.

How to cite: Maurer-Rurack, U., Liebscher, A., and Magri, F.: State of the scientific and technical knowledge about limiting temperatures in the Repository Site Selection process of Germany with simultaneous consideration to Europe and other European repository concepts , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20302, https://doi.org/10.5194/egusphere-egu2020-20302, 2020.

Nuclear power generation became popular in the 1950s in industrialised countries as an alternative to fossil energy sources to provide large amounts of low cost, low carbon energy. Currently 6% of the world’s energy supply is produced in 451 nuclear reactors across 30 countries. However, nuclear power generation has a serious disadvantage and hidden cost: the accumulation and disposal of spent fuel or high level nuclear waste (HLW) - notably highly radioactive nuclear fission products and the absence of suitable long-term storage solutions, threatening livestock and the environment. Sustainable disposal of HLW holds many challenges: fluid and heat transfer may induce strongly coupled undesirable thermal, hydrological, mechanical and chemical processes.

A crystalline rock repository construction license has been accomplished by Finland in 2015 for the first long-term HLW repository worldwide. In Germany, a consortium of federal offices is exploring the opportunity of establishing a long-term underground repository in crystalline rock for HLW as an alternative to potential repositories in salt rock and mudrock.

The aim of this research is to de-risk hypothetical storage solutions for long-term HLW repositories in Germany in crystalline rock. As no geological site must be alluded to for legal reasons during the repository site investigation process at the time being, flow is modelled for a generic fractured rock site based on academic studies of crystalline rock. An inverse problem approach is applied to investigate hydraulic site requirements for the long-term storage of HLW and provide footing for the analysis of coupled thermal, hydrological, mechanical and chemical processes. 

This work demonstrates progress towards finding a long-term storage solution for HLW in Germany through evaluating hydrological processes in a generic crystalline rock site. Through Oda analysis and simulating steady-state flow and particle tracking in a synthetic discrete fracture network (DFN), degrees of fracture connectivity and hydraulic conductivity of fractures have been identified for the hydraulic (boundary) conditions in a repository in crystalline rock.

How to cite: Weihmann, S. and Maßmann, J.: Creating a generic model of a high level waste (HLW) repository in crystalline rock and determining hydraulic parameters to investigate minimum requirements to the host rock for a safe storage location according to national German law, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19930, https://doi.org/10.5194/egusphere-egu2020-19930, 2020.

EGU2020-22601 | Displays | ERE4.2

Towards best possible safety - Current regulatory research for the German site selection process for high-level radioactive waste disposal

Axel Liebscher, Christoph Borkel, Ute Maurer-Rurack, and Michael Jendras

The German Site Selection Act (Standortauswahlgesetz – StandAG) defines the search for and selection of the national German site with best possible safety for a disposal facility for high-level radioactive waste. The Federal Office for the Safety of Nuclear Waste Management (BASE) is the federal regulatory authority for radioactive waste disposal. BASE supervises the site selection process for a repository for high-level radioactive waste and is responsible for the accompanying public participation. To fulfill its tasks according to the state of science and technology, task related research forms an integral part of BASEs activities. Current research activities in the context of the site selection process address geoscientific questions, methodological aspects of the implementation of the site selection process, and public participation aspects. This contribution provides an overview on the current geoscientific and methodological research activities of BASE.

According to § 16 StandAG , the national implementer (Bundesgesellschaft für Endlagerung  mbH) has to execute surface-based exploration and BASE has to review and define the respective exploration program. Therefore, the two projects MessEr and übErStand compiled state of science and technology with regard to surface based exploration methods. The foci were on methods suitable for addressing the criteria and requirements set out in the German Site Selection Act.

The project KaStör reviewed the current knowledge on active faults and fault zones in Germany and studied methodological approaches to date and identify the activity of faulting. The results support BASE to review the application of the exclusion criteria for areas with “active faults zones” according to § 22 (2) StandAG.

For the time being, § 27 (4) StandAG defines 100 °C as precautionary maximum temperature at the outer surface of waste canisters for all host rocks. The project Grenztemperatur compiled and studied the temperature dependency of the different THMC/B processes according to available FEP catalogues for rock salt, clay stone, and crystalline rock. The project also identified open and pending research questions and describes ways to define host rock specific maximum temperatures based on specific disposal and safety concepts.

During the site selection process, safety oriented weighting of different criteria and comparison of different potential regions and sites have to be performed. The project MaBeSt studied and reviewed methodological approaches to this weighting and comparison problem with special emphasis on multi criteria analysis (MCA) and multi criteria decision analysis (MCDA).

Key requirement for safe geological disposal of nuclear waste is barrier integrity. The project PeTroS experimentally studied potential percolation mechanisms of fluids within rock salt at isotropic conditions at disposal relevant pressures and temperatures.

How to cite: Liebscher, A., Borkel, C., Maurer-Rurack, U., and Jendras, M.: Towards best possible safety - Current regulatory research for the German site selection process for high-level radioactive waste disposal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22601, https://doi.org/10.5194/egusphere-egu2020-22601, 2020.

EGU2020-22535 | Displays | ERE4.2

Sensitivity analyses and uncertainty quantification in THM models: a benchmark study

Jörg Buchwald, Aqeel Chaudhry, Keita Yoshioka, Olaf Kolditz, and Thomas Nagel

Coupled thermo-hydro-mechanical (THM) models are used for the assessment of nuclear waste disposal, reservoir engineering, and other branches of geo-environmental engineering. Model-based decision-making and design optimization in these domains require sensitivity analyses (SA) and uncertainty quantification (UQ) methods that are suitable for coupled THM problems on an engineering scale. Due to different coupling levels, non-linearities, and large spatial and temporal extents, these analyses can often be challenging both conceptually and computationally.

For an initial evaluation in a setting relevant to nuclear waste disposal we start by employing an analytical solution for thermal consolidation around a point heat source which encompasses the most relevant primary couplings and allows us to cover the entire parameter space robustly and efficiently. For uncertainty quantification, we applied an experimental design (DoE-) based history-matching approach. This approach uses DoE methods to construct a proxy model, which is used later for efficient Monte Carlo sampling and subsequent filtering of the uncertainty space of the history-match error. As a result, we obtain a family of curves that is compatible with the prior parameter set and experimental data to match, which then enables further uncertainty quantification. In our work, we demonstrate the applicability of the workflow and discuss its particular suitability to this problem class, including its (in-)sensitivity to prior parameter distribution assumptions.

For SA, we contrast the conclusions drawn via two different approaches: local one variable at a time (OVAT) and global sensitivity analysis (GSA) based on Sobol indices for different spatio-temporal settings to observe near and far-field effects as well as early- and late-stage system response. The conducted studies can serve as a benchmark for UQ and SA software designed around numerical THM simulators.

How to cite: Buchwald, J., Chaudhry, A., Yoshioka, K., Kolditz, O., and Nagel, T.: Sensitivity analyses and uncertainty quantification in THM models: a benchmark study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22535, https://doi.org/10.5194/egusphere-egu2020-22535, 2020.

EGU2020-21147 | Displays | ERE4.2

Hydrogeological characteristics of candidate sites for high-level waste disposal in South Korea

Jinyoung Park, Kyoungtae Ko, Minhee Lee, and Minjune Yang

Geological disposal of High-Level Radioactive Waste (HLRW) is considered to be one of the best disposal methods that can stably and semi-permanently isolate high-level radioactive waste from the biosphere. In this study, three types of potential host rocks for HLRW disposal were selected and the hydrogeological characteristics were investigated using deep drilling cores collected at about 50 m intervals in the borehole of a depth of 1 km. The rocks used in this study were granites and gneiss which are crystalline rock, and mudstone which is a sedimentary rock. The results of the study showed that the average porosity of granite was 0.48% and the permeability ranged from 7.87 × 10-19 m2 to 1.39 × 10-21 m2 except for samples outside the measurement limit (4.04 × 10-22 m2). The average porosity of gneiss was 0.49% and the permeability ranged from 3.62 × 10-18 m2 to 4.58 × 10-22 m2. The average porosity of mudstones was 3.62% and the values of permeability for most mudstone samples were lower than the measurement limit. For SEM-EDS analysis, many microcracks were observed in the crystalline rock samples having high permeability. On the other hand, there were almost no microcracks in crystalline rock samples having low permeability, and even if there were cracks, the cracks were filled with fillers such as clay minerals. These results indicate that the presence of microcracks or the filling of cracks in crystalline rocks has a significant effect on the flow of groundwater through the host rock.

How to cite: Park, J., Ko, K., Lee, M., and Yang, M.: Hydrogeological characteristics of candidate sites for high-level waste disposal in South Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21147, https://doi.org/10.5194/egusphere-egu2020-21147, 2020.

EGU2020-2821 | Displays | ERE4.2

Quantification and Reduction of Uncertainties in 3D Stress Models

Moritz Ziegler and Oliver Heidbach

The undisturbed stress state of a potential site for nuclear waste disposal is of key importance for the assessment of long-term stability of the geotechnical installations and for seismic hazard assessment. In particular, the stability of pre-existing faults within and near a repository can only be evaluated with the knowledge of the initial stress state. Information on stress magnitudes is rare and unevenly distributed. Thus, 3D geomechanical-numerical modelling is used to estimate the stress state in an area of interest. However, due to the limitation of available data, the modelled stress state has a large uncertainty which has not been rigorously quantified yet. We present an approach to quantify the uncertainties in a 3D geomechanical-numerical modelled stress field. We combine the available SHmax and Shmin data records to pairs. For each pair we compute an individual model scenario. At each location in the model each scenario contains the full stress tensor. Then, from all model scenarios we compute an average value and a standard deviation for each component of the full stress tensor at each location within the model. This provides a comprehensive assessment of the stress state and its uncertainties.

Furthermore, we present an approach to reduce the previously quantified uncertainties in the model results: We use additional borehole observables (Formation Integrity Tests) and observed seismicity and - if available - its focal mechanisms. These observables cannot provide any data records on the stress state. Yet, the information that can be extracted is valuable as it contains upper boundaries for the magnitudes of the minimum principal stress (Formation Integrity Tests) and the maximum principal stress/differential stress (seismicity), respectively. These boundaries are compared to the stress states in the individual model scenarios. Then, each scenario is assigned a weight based on its agreement with the additional data. This allows computing a weighted average and a standard deviation. The resulting standard deviation is clearly smaller compared to the unweighted approach and small changes in the average stress state are observed. Thus, even with only limited data record availability, a quantification and even a significant reduction of uncertainties in the modelling results is possible which increases the significance and value of the model.

How to cite: Ziegler, M. and Heidbach, O.: Quantification and Reduction of Uncertainties in 3D Stress Models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2821, https://doi.org/10.5194/egusphere-egu2020-2821, 2020.

EGU2020-4078 | Displays | ERE4.2

Cs batch sorption and column transport experiments on sand from the Yamin plain, Israel – Experimental results and modelling

Ofra Klein-BenDavid, Noa Balaban, Svetlana Gelfer, Ronen Komerian, David Saban, and Ravid Rosenzweig

The Yanim plain hosts the national Israeli radioactive waste disposal site. The site is located on the Miocene aged Hazeva formation, comprised of loose sand, sandstone and dispersed clay layers. The current research examines the sorption capacity of the local sand to solutions doped with Cs ions. The sand contains ~95% quartz and ~5% of various clays, carbonates, and oxides. Batch sorption experiments were conducted at a liquid to solid ratio of 10. Two end-member solutions were used, fresh (MQ) and concentrated (Na-Nitrate solution). Both solutions were doped with 0.1, 1, 10, 100 and 1000 ppm of Cs (as a nitrate). For the MQ experiments Kd values ranged between ~2 and ~1300, where the highest Kds were registered for the 1 ppm doping level, and the smallest Kds were for the 1000 ppm doping level. For the concentrated solution Kd values ranged between ~0 and ~1.5, where the highest Kds were for the 1 ppm doping level, for all other doping levels Kds were <1. Freundlich and Langmuir isotherm calculations revealed a significantly better correlation on a linearized Freundlich isotherm, indicating a multi-layer and multi-site sorption model, with a similar slope for both solutions, indicating a common sorption mechanism. Column transport experiments (L=25cm, r=2cm, φ=30%, 1PV=180cc) have shown minimal retardation of the Cs in the concentrated solution flow experiments (R= ~2). A second, probably colloid-related peak, showed an early breakthrough with respect to a conservative color tracer.  On the other hand, when MQ was run in the column no breakthrough was observed within 10 column pore volumes. In one fresh experiment a very small colloid related peak was found with breakthrough similar to the conservative tracer. We used the CXTFIT model to calculated the dispersity (λ [L]) and normalized velocity (V) of the measured tracer. For the conservative tracer the values were λ=0.13 cm and V=0.9 cm. For Cs transport in the concentrated solution λ=0.22 cm and V=1.6. Thus, it may be concluded that even in similar doping levels in the same matrix the solution chemistry will play a major role in contaminant retardation. Thus, rain episodes which abruptly change the solution chemistry, can significantly affect solute and colloid mobility.

How to cite: Klein-BenDavid, O., Balaban, N., Gelfer, S., Komerian, R., Saban, D., and Rosenzweig, R.: Cs batch sorption and column transport experiments on sand from the Yamin plain, Israel – Experimental results and modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4078, https://doi.org/10.5194/egusphere-egu2020-4078, 2020.

EGU2020-5738 | Displays | ERE4.2

Monitoring and Retrieval of High-Level Radioactive Waste

Volker Mintzlaff and Joachim Stahlmann

Monitoring and Retrieval of High-Level Radioactive Waste

The retrievability of high-level radioactive waste (HAW) is defined as the option to retrieve previously emplaced waste from a respository. This is a design requirement in many countries, as for example in Germany, justified by the need to react on possible failures in the repository system.

Retrievability affects the footprint of the repository (Léon-Vargas et al., 2017) and requires a monitoring program (Stahlmann et al., 2018), as the decision on retrieval should be justified on sound basis. For a holistic analysis of the design consequences of retrievability of high-level radioactive waste it is necessary to get information about the retrieval process itself. In TRANSENS, a transdisciplinary research platform for HAW disposal research, the retrieval process will be analyzed in general.

The presentation will focus on a generic repository approach based upon Stahlmann et al. (2018) modified for the analysis of the retrieval process. Main impacts of the retrieval works on the host rock were identified, as the effects of the redriven emplacement drifts on the repository system. The presentation will focus on these processes and give a short outlook on their consequences for a monitoring program.

 

Leon Vargas, R.; Stahlmann, J.; Mintzlaff, V. (2017): Thermal impact in the geometrical settings in deep geological repositories for HLW with retrievability and monitoring. 16th International High-Level Radioactive Waste Management Conference (IHLRWM 2017), Charlotte, NC, April 9-13, 2017.

Stahlmann, J.; Mintzlaff, V.; León Vargas, R.P.; Epkenhans, I. (2018): Normalszenarien und Monitoringkonzepte für Tiefenlager mit der Option Rückholung. Generische Tiefenlagermodelle mit Option zur Rückholung der radioaktiven Reststoffe. ENTRIA-Arbeitsbericht-15. Braunschweig.

How to cite: Mintzlaff, V. and Stahlmann, J.: Monitoring and Retrieval of High-Level Radioactive Waste, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5738, https://doi.org/10.5194/egusphere-egu2020-5738, 2020.

EGU2020-5936 | Displays | ERE4.2

Impact of deposition borehole geometry on mechanical spalling in nuclear waste repositories

Maria Cristina Saceanu, Adriana Paluszny, Robert Zimmerman, and Diego Mas Ivars

Predictions of rock spalling around deep-drilled boreholes and tunnels in underground geologic repositories in crystalline rocks remain a significant challenge, due to the heterogeneities present in the rock mass, uncertain stress fields, and the complex thermo-mechanical behaviour of the rock mass at elevated temperatures.

This study presents a three-dimensional numerical analysis of multiple fracture growth leading to spalling around a deposition borehole. The mechanical spalling due to stress amplification after drilling is simulated using a finite element-based discrete fracture growth simulator. Fractures are grown by computing stress intensity factors at each fracture tip, and the mesh is adapted to accommodate the changing fracture geometries at every growth step. The model is validated using the Äspö Pillar Stability Experiment (APSE), calibrated to simulate the drilling of a borehole in the Forsmark granite, and subjected to a far-field anisotropic triaxial stress, corresponding to the in situ stress model from Forsmark. The deposition tunnel is implicitly simulated by attaching the deposition borehole to a free domain boundary.

The effect of borehole geometry on the predicted spalling around a typical deposition borehole is studied. The cylindrical borehole is modified at the top to provide an access ramp for the spent fuel canisters, which can effectively improve the repository design by reducing the height of the deposition tunnel. Three cases are investigated, in which the borehole top is cylindrical, conical, and wedge-shaped, respectively. Numerical results show that spalling occurs in all cases, but the borehole geometry affects fracture nucleation and growth patterns. The enlargement of the borehole top induces higher stress concentrations at the borehole-tunnel junction, increasing the severity of spalling at the top of the borehole. The final spalled zone and the fractures-borehole interaction are illustrated for each stress and geometry scenario.

How to cite: Saceanu, M. C., Paluszny, A., Zimmerman, R., and Mas Ivars, D.: Impact of deposition borehole geometry on mechanical spalling in nuclear waste repositories, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5936, https://doi.org/10.5194/egusphere-egu2020-5936, 2020.

In the multi-barrier system of HLW repository, overpack is the first barrier to isolate high-level radioactive nuclides from biosphere, and Low carbon steel has been considered to be a promising candidate material for manufacturing the oberpack due to its good mechanical performance and workability and weldability. However, during thousands of years of geological disposal, the corrosion resistance of low carbon steel and its corrosion evolution behavior are the first element that must be fully understood, because it determines the life cycle of the artificial barrier.

Conventional studies had suggested that the corrosion of low carbon steel under the deep geological environment was driven by hydrogen evolution reaction (HER) based on that the dissolved oxygen was completely depleted during the long term disposal. However, the residual oxygen content is a critical factor to determine the corrosion mode of cathodic reduction reaction. Thermodynamics data indicated that the initial ferrous corrosion products formed in the deaerated bicarbonate solution can be chemically oxidized into ferric substance by the trace content of dissolved oxygen, and the accumulated FeOOH as a cathodic depolarizer significantly increased the open circuit potential and enhanced the corrosion rate of the low carbon steel. Moreover, chloride and sulfate in the simulated groundwater can reduce the increase of open circuit potential but it still promotes the corrosion of the low carbon steel. As the environments contained aggressive anions and high concentration of dissolved oxygen, low carbon steel was prone to suffer from the localized corrosion and the corrosion rate was obviously increased. By alloying with some contents of Ni and Cu, the corrosion rate of low alloy steel was decreased by an order of magnitude and it was less prone to suffer from the localized corrosion.

Under the conditions of simulated groundwater with different content of GMZ bentonite,the bentonite colloidal particle layer attached to the surface of low carbon steel showed blocking effect on resisting oxygen diffusion to the steel substrate, which consequently decrease the further oxidation of ferrous to ferric substances and the corrosion rate of low carbon steel. However, the barrier performance of bentonite colloids would be deteriorated due to their coagulation caused by the ferrous ions dissolved from the steel substrate. High content of bentonite was beneficial to maintain and to prolong the stabilization of the barrier system. An equivalent circuit model which correlates with the interfacial structure between electrode substrate and rust and bentonite layer was proposed. The fitting results showed a very good match between the model and experimental data, and the evolution of the results was also in agreement with real changes.

How to cite: Dong, J.: Corrosion study of low carbon steel under simulated geological disposal environments for HLW in China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6413, https://doi.org/10.5194/egusphere-egu2020-6413, 2020.

EGU2020-7897 | Displays | ERE4.2

Large-scale tests to investigate MgO concrete with a long-term stable 3-1-8 phase in the Sondershausen and Teutschenthal mines

Jan Aurich, Daniela Freyer, Matthias Gruner, and Wolfram Kudla

These abstract bases on the R & D project ELSA Phase II - Concept development for shaft seals and testing of sealing elements for HAW repositories, funded by the German Federal Ministry of Energy and Economic Affairs.

The installation of sealing elements in salt rock requires a mechanical support system, which is chemical compatible with the host rock. In future HAW-repositories abutments and sealing elements within the shafts and drifts could be made of magnesia building material with the long term stable 3-1-8 binder phase, if solution containing magnesium can attack the seal.

In 2014 a first large-scale experiment was performed in the Sondershausen salt mine in Germany. A vertical borehole with the depth of two meters and a diameter of 1.1 meter was filled with the magnesia-based concrete. Several sensors measured the development of temperature, comprehensive stress and expansion within the test construction for approximately one year. During the binding reaction the temperature increased by 55 K in the center. After 150 days, the expansion in axial direction reached 2.4 mm/m and 1.1 mm/m in radial direction.

In 2018 a second large-scale-experiment was performed in the Teutschenthal salt mine, Germany to continue the investigations. A new vertical borehole with the depth of 3.5 meters and a diameter of 1.3 meters was filled with the same material. The temperature in the center increased by 40 K during the binding reaction and decreased down to the ambient temperature after 20 days. In result of the first experiences, the stress sensor range was increased. After one year a comprehensive stress of 6.2 MPa was measured at the contour and is still evolving at this point (early 2020). The maximum axial expansion reached 7.9 mm/m and stays at this level. The maximum radial expansion reached 0.7 mm/m 20 days after concreting and decreased subsequently. This material behavior corresponds to the high comprehensive stress level.

The second experiment is equipped with a pressure chamber at the bottom. A first determination of the integral gas permeability revealed a value of approx. 3E-18 m² to 3E-17 m². In the near term a multistage pressurization of the construction is planned, using a saturated NaCl solution to evaluate the sealing ability.

This contribution reports on the measured parameters (temperature, stress, strain) of the two large-scale tests with long-term stable MgO-concrete and the composition requirements to obtain a long-term stable MgO concrete. Long-term stable MgO concrete with 3-1-8 phase has been used for the first time in these tests. The measured test-results are the foundation for modelling the behaviour of the MgO-concrete.

How to cite: Aurich, J., Freyer, D., Gruner, M., and Kudla, W.: Large-scale tests to investigate MgO concrete with a long-term stable 3-1-8 phase in the Sondershausen and Teutschenthal mines, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7897, https://doi.org/10.5194/egusphere-egu2020-7897, 2020.

EGU2020-10772 | Displays | ERE4.2

Immobilization of uranium by phosphate and carbonate crystallization as an improvement of engineering barriers.

Rinat Gabitov, Artas Migdisov, Nguyen Anh, Jimenez Angel, Van Hartesveldt Noah, Perez-Huerta Alberto, Sadekov Aleksey, Sauer Kirsten, Baker Jason, Paul Varun, Caporuscio Florie, Xu Hongwu, and Roback Robert

Studies on incorporation of radionuclides into the crystal structures of phosphate minerals strongly indicate that uranium and its mobile fission products can be efficiently immobilized through uptake from aqueous solution by formation of phosphate and carbonate minerals. Aiming at development of a new engineered backfill material, we have investigated uptake of uranium at a range of temperatures similar to those expected at waste repository sites, where thermal peak of the waste package (heated by radioactive decay) is ~300°C (Greenburg and Wen 2013). The available literature data on uranium uptake by phosphates are limited to ambient temperatures (e.g. Arey et al. 1999), and to our best knowledge no experimental studies on uranium uptake by phosphates and carbonate at hydrothermal conditions have been performed.

Experiments were conducted in the autoclaves at saturated water pressure and 200-350°C, where metastable phosphate (brushite) and carbonate (aragonite) were transformed to apatite/monetite and calcite in NaCl solutions. Uranium was introduced into autoclave in separate tubes in the forms of U3O8 and UO3 in experiments at reduced and oxidized conditions. Oxidation state of dissolved uranium (U4+ or U6+) was controlled by addition of solid redox buffers into autoclaves.

X-ray diffraction (XRD) and backscattered electron diffraction (EBSD) of crystalline products allowed estimation of mineral transformation rate. Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS allowed obtaining uranium content in crystals and its concentration in co-existed solution. Partition coefficient (D) of uranium was calculated as the ratio of uranium content in the solid to uranium concentration in the solution. Selected solids were examined with synchrotron-based X-ray absorption spectroscopy (XAS).

Overall, our results showed: 1) brushite transforms to monetite and apatite mixture during 6 days, but up to 1 month is required for complete transformation to apatite; 2) mineralogy of the final phase (monetite or hydroxyapatite) depends on ionic strength of the solution (confirmed by thermodynamic calculations); 3) uranium is compatible with phosphate and carbonate minerals, where D could be as high as 1000; 4) uptake of U4+ by calcite is higher than that of U6+ by up to a factor of 100; 5) uranium incorporates into calcite structure as U6+ at oxidized conditions. Additional analyses are pending and results will be presented at EGU meeting.

 

References

Arey J.S., Seaman J.C., and Bertsch P.M. (1999) Environ. Sci. Technol.  33, 337-342.

Greenburg H.R. and Wen J. (2013) LLNL-TR639869-DRAFT, 38.

How to cite: Gabitov, R., Migdisov, A., Anh, N., Angel, J., Noah, V. H., Alberto, P.-H., Aleksey, S., Kirsten, S., Jason, B., Varun, P., Florie, C., Hongwu, X., and Robert, R.: Immobilization of uranium by phosphate and carbonate crystallization as an improvement of engineering barriers., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10772, https://doi.org/10.5194/egusphere-egu2020-10772, 2020.

EGU2020-13981 | Displays | ERE4.2

Assessment of effective infiltration in the deep arid vadose zone of the Negev, Israel

Noa Balaban, Ravid Rosenzweig, Philip Stauffer, Ofra Klein-BenDavid, Avraham Dody, Ran Calvo, Stephen Kuluris, and Gilles Bussod

The Israeli national site for radioactive waste is situated in the Yamin Plain, within the Negev desert. Estimation of  water recharge to the ~500 m deep vadose zone underlying the site  is crucial for assessing risks related to contaminants transport. However, estimation of water fluxes in deep arid vadose zones is a challenging task because of their small magnitude and the lack of a direct measurement technology. Studies conducted in a deep arid vadose zone in Nevada, USA point to complex transient flow dynamics, in which the direction of water flow in the top of the vadose zone is upward while in the rest of the section water flows downwards to the water table.    

            In this study we present a combination of techniques which are used to obtain an initial evaluation of the water dynamics in this environment. These techniques include direct and continuous measurements of water content at the upper 5.5 m of the vadose zone through a vadose zone monitoring system which contain FTDR water content sensors; profiles of water content, leachable chloride and soil texture; and numerical modeling.

            The monitoring of the upper 5.5 m of the vadose zone during the years 2014-2018 indicates that even after extreme rain events of ~ 50 mm (constituting more than a half of the annual rainfall) there is no water infiltration to the lower parts of the section. These results exemplified the need for an alternative method to detect low water fluxes that characterize this arid area. We therefore use an inverse modeling approach where numerical solutions of water movement in the vadose zone are fitted to measured profiles of chemical and physical parameters from two shallow boreholes in the Yamin Plain. The water content of both boreholes revealed an extremely dry environment, with low saturations and high pore-water chloride concentrations, above 15,000 mg/l, in certain depths. Peak chloride concentrations did not coincide in the two boreholes, raising the question whether these peaks are connected to water fluxes or to changes in soil texture, which can inhibit water infiltration.

             Numerical simulations were then used to solve water flow and solute transport. Input parameters, including chloride deposition rate, precipitation rate, and surface run-off fraction were varied to fit the measured chloride profiles. Results indicate very small water fluxes of less than 1 mm/yr in the bottom of the vadoze zone. The simulations also show that the mass of chloride in the profile is less than the one expected based on estimated chloride deposition rate and published records of paleo-rain. These results suggest either a delayed climate shift to dry conditions compared to previous estimates for the region (8000 yr BP), and/or a partial input of the 4 g/m2/yr of deposited chloride, possibly due to runoff.

How to cite: Balaban, N., Rosenzweig, R., Stauffer, P., Klein-BenDavid, O., Dody, A., Calvo, R., Kuluris, S., and Bussod, G.: Assessment of effective infiltration in the deep arid vadose zone of the Negev, Israel, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13981, https://doi.org/10.5194/egusphere-egu2020-13981, 2020.

EGU2020-20522 | Displays | ERE4.2

Methodology of preliminary safety assessments in the site selection procedure in Germany

Wolfram Rühaak, Phillip Kreye, Eva-Maria Hoyer, Johanna Wolf, Florian Panitz, and Dennis Gawletta

In Germany, the site selection for a repository for radioactive waste in deep geological formations was (re-) started in 2017 with the Repository Site Selection Act coming into force. The Site Selection Act envisages preliminary safety assessments as a measure to ensure the safety of a considered site.

The focus of the presentation will be the methodology of the preliminary safety assessments as it is derived from the legal requirements. In this context, the Federal Ministry for Environment, Nature Conservation and Nuclear Safety published the draft of the regulation on the safety requirements for the disposal of high-level radioactive waste in summer 2019. Article 2 of this regulation contains the requirements for the implementation of preliminary safety assessments in the site selection procedure. One essential aspect is the systematical identification and characterization of uncertainties. We will discuss the key features of the handling of uncertainties in the site selection procedure, especially with regard to numerical reactive transport modelling. The German Site Selection Act is divided into several steps with increasing level of detail. The identification and quantification of uncertainties plays a major role to improve quality and plausibility in each step. Well-prepared explorations for instance, need to be addressed in a way to minimise data uncertainties. In addition, the handling of uncertainties in safety assessments on an international level is evaluated.

How to cite: Rühaak, W., Kreye, P., Hoyer, E.-M., Wolf, J., Panitz, F., and Gawletta, D.: Methodology of preliminary safety assessments in the site selection procedure in Germany , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20522, https://doi.org/10.5194/egusphere-egu2020-20522, 2020.

EGU2020-20570 | Displays | ERE4.2

Methods for in-situ HM characterization of claystone at the Mont Terri Rock Laboratory

Sina Hale, Xavier Ries, David Jaeggi, and Philipp Blum

Claystones are considered to represent an important barrier rock in the context of nuclear waste storage. When cavities are opened underground, the rock mass in the near vicinity of the constructed repository is strongly affected by unloading, which is generally referred to as the Excavation Disturbed Zone (EDZ). This area is primarily characterized by newly formed unloading fractures, leading to an enhanced hydraulic transmissivity of the EDZ in comparison to the intact host rock. This phenomenon can affect the integrity of a geologic barrier as open fractures provide possible flow paths and endanger the long-term safety of underground storage facilities. A precise characterization of the EDZ is therefore essential for risk assessment and strategy development in terms of radioactive waste disposal.

In this study the Excavation Disturbed Zone (EDZ) of the Mont Terri Rock Laboratory is investigated with regard to hydraulic, mechanical and geophysical properties by using three simple field measuring devices, (1) portable permeameter, (2) microscope camera and (3) needle penetration test (NPT). The hydraulic aperture of accessible joints within the Opalinus Clay formation in the EZ-B niche is measured by a portable transient-airflow permeameter. The instrument was validated by flow-through experiments and is able to accurately determine hydraulic fracture apertures down to about 10 µm. In-situ measurements were carried out at 43 points and show a mean hydraulic aperture of 84 ± 23 µm, extending over a range from 20 to 100 µm. Fracture apertures do not change with increasing distance to the gallery in the accessible area of uncovered claystone.

For the same set of measuring points, the mechanical fracture aperture was determined by a digital microscope camera. Mechanical fracture apertures in the EZ-B niche ranged between 16 and 1400 µm with a mean value of 268 ± 276 µm. As comparable hydraulic apertures can be derived from the measured mechanical aperture by using empirical relations based on estimated joint surface roughness, the microscope camera represents a valuable alternative besides the air permeameter. The hydraulic characterization of the EDZ proves the existence of accessible fluid pathways within the Opalinus Clay of the Mont Terri Rock Laboratory, even about 15 years after tunnel excavation.

The mechanical and geophysical properties of the EDZ are investigated by a needle penetration test (NPT). Whereas the needle penetration index (NPI) is strongly influenced by bedding anisotropy, the influence of the EDZ is negligible. The NPT proves to be a suitable tool for estimating mechanical properties by using different empirical relations. Especially for the uniaxial compressive strength, a high correlation with literature values is observed. In contrast, geophysical parameters such as P-wave velocity cannot be reliably determined with this method. The obtained field data could be used as a reasonable input for numerical models that aim at investigating swelling and shrinking behavior of the Opalinus Clay with regard to self-sealing processes within the EDZ.

How to cite: Hale, S., Ries, X., Jaeggi, D., and Blum, P.: Methods for in-situ HM characterization of claystone at the Mont Terri Rock Laboratory, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20570, https://doi.org/10.5194/egusphere-egu2020-20570, 2020.

EGU2020-22481 | Displays | ERE4.2

A novel hydro-mechanical model for swelling of argillaceous material

Antonia Nitsch, Jan Machacek, Julia Leuthold, Carlos Grandas Tavera, and Torsten Wichtmann

The safe disposal of nuclear and radioactive waste is one of the most challenging tasks in current and future environmental geosciences. In so-called deep geotechnical repositories nuclear waste barrels are either directly embedded in argillaceous buffers located in deep bedrock formations or the buffer is placed at distance to seal the deposit tunnel cavity. Due to their swelling capacity and low hydraulic permeability bentonite- or clay-based materials are widely regarded as suitable buffer materials.

The design of these deep geotechnical repositories is not a simple task and its evaluation and improvement is still subject of current research. During the design, finite element models can be used to simulate the behavior of the buffer and the bedrock subjected to hydro-mechanical loading. In order to achieve realistic predictions, these models have to meet several requirements: coupled hydro-mechanical simulation techniques are needed to capture the dependence of the swelling process of the buffer (or the bedrock) on the amount of supplied mountain water. Further, the swelling induced changes in the hydraulic permeability, strain and stress should be addressed in the simulations. The swelling process, however, is a path-dependent process which should also be taken into account by the numerical model.

Although several models capable of predicting the swelling process already exist, a hydro-mechanical model, which incorporates the capability of modelling swelling of an initially fully saturated material depending on its loading history, still lacks.

 

The proposed constitutive model is aimed to be suitable for application in both the dry and the swollen state. The swelling process is activated by a change in volumetric water content. We therefore introduce a swelling water content which defines how much of the pore water contributes to the swelling of the porous medium. The swelling water is assumed to be attached to the material particles and cannot be reduced by mechanical processes. Thus, the swelling process is regarded irreversible. To incorporate the path dependency of the swelling process, the evolution of the swelling water content depends on the effective stress state. Irreversible changes of the material due to swelling, e.g. a reduction of the stiffness, are modelled by introducing a swelling degree, which allows the transformation of material properties from the dry material to those of the swollen material.

The experimental studies which form the basis of the proposed constitutive model include oedometric swelling tests, standard oedometer tests and measurements for the determination of the suction-saturation relation and the hydraulic permeability. All tests are carried out on reconstituted samples of opalinus clay.

The proposed hydro-mechanical model is implemented using the finite element method and validated by numerical simulations. First simulations are in good agreement with the experimental results.

How to cite: Nitsch, A., Machacek, J., Leuthold, J., Grandas Tavera, C., and Wichtmann, T.: A novel hydro-mechanical model for swelling of argillaceous material, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22481, https://doi.org/10.5194/egusphere-egu2020-22481, 2020.

ERE5.1 – Constructional GeoMaterials: Resources, Properties, Uses, and Environmental Interactions

Different stone qualities in masonry walls cause considerable problems on masonry walls during restoration works. The properties of limestone show significant variations due to differences in sedimentary structures which are might not be visible at the scale of laboratory test specimens. Even at one quarry level, there could be major differences in properties due to the cross-bedding or tilted rock beds. Physical parameters of 3 typical types of porous limestone (fine-, medium-, coarse-grained) were studied under laboratory conditions in order to assess an explanation for variations in weathering forms on masonries of historical buildings. Laboratory experiments were performed to determine the bulk density, water absorption, apparent porosity, ultrasonic pulse velocity under dry and water-saturated conditions. Aim of this research is to find correlations between physical parameters of limestones and show considerable diversity in properties. Our results indicate that there is a relationship between dry and water-saturated bulk density vs. ultrasonic pulse velocity and dry and water-saturated bulk density vs. apparent porosity, respectively. It is well known that microstructure influences the damage mechanism of stones. Our research demonstrates that variations exist in the stone fabric even at quarry level, based on the samples of Sóskút quarry. The different limestone lithologies were used side by side in historical buildings; therefore our results help experts during restoration works in decay mapping of monuments.

How to cite: Papay, Z., Rozgonyi-Boissinot, N., and Török, Á.: The relationship between the bulk density, the apparent porosity and ultrasonic pulse velocity of highly porous limestone, examples from Hungary, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19585, https://doi.org/10.5194/egusphere-egu2020-19585, 2020.

EGU2020-21284 | Displays | ERE5.1

Spatiotemporal investigation of material property changes in building stone following initial emplacement

Brian Johnston, Jennifer McKinley, and Patricia Warke

Visual inspection of deterioration phenomena across the façades of a historical monument demonstrates the spatial variability of weathering processes. Multiple previous weathering simulation and exposure trials have been developed to investigate the connection between weathering processes and spatial variability of response. However, in landscape systems theory, stability is a function of both spatial and temporal components. Temporal sensitivity is a function of both the magnitude and frequency of formative events and the spatial sensitivity of the material.

One area of urban stone decay literature that requires further attention is the initial response of quarry ‘fresh’ material to emplacement within a building. Previous small-scale investigations have demonstrated that alteration commences within a few months to a year of emplacement. These early changes to the material will have a lasting influence upon the development of future weathering processes and their spatial distribution. The necessity to investigate both the spatial and temporal components of this transition, well suits the capabilities of spatiotemporal kriging tools.

The influence of aspect upon the initial alterations of the material’s properties are of significance to interpreting the weathering response to transition. Therefore, five sandstone blocks were placed within an exposure frame, located in South Belfast, for a duration of one year. One block was exposed to each of the four cardinal points whilst the fifth was positioned to represent a horizontal surface on a structure, such as a window sill or balustrade. Permeability measurements were recorded in a regular grid across the exposed surface of the block once a month, creating a data set that is both spatially and temporally dense. No previous studies have collected a similar quantity of points, across both space and time, to investigate weathering processes. The application of only spatial techniques proved to be inappropriate to fully interpret the complexity of the changing material properties. Use of spatiotemporal kriging allowed the modelling of the sample blocks to illustrate the changing material properties over time. The outcome of this work is the development of a better-informed understanding of the initial alteration of building stones placed within the urban environment. Additionally, the observed variance of the temporal component has improved our understanding of the nature of early episodic change within the stone decay system.

How to cite: Johnston, B., McKinley, J., and Warke, P.: Spatiotemporal investigation of material property changes in building stone following initial emplacement, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21284, https://doi.org/10.5194/egusphere-egu2020-21284, 2020.

EGU2020-18178 | Displays | ERE5.1

Weathering and conservation of tuff stone

Maria Stuff, Katrin Rübner, Carsten Prinz, Nicole Rische, Matthias Chronz, and Hans-Carsten Kühne

Tuff stone, a porous pyroclastic rock, is a light and soft material. Hence, tuff is easy to handle and to transport. It is used as construction material in numerous historical buildings. Due to its high water absorption and retention potential, heterogeneous pore structure, and clay mineral content, tuff is highly sensitive to weathering by moisture expansion and salt crystallization [1; 2]. The search for a protective agent for tuff stone has been subject to scientific studies for several decades. Yet, due to the high variability and heterogeneity of tuff stone, no generally applicable means to protect tuff against weathering has been found to date. Instead, case specific solutions are developed to preserve historical buildings. Often it is necessary to remove weathered parts of the stone or exchange whole tuff ashlars to ensure the stability of the construction. Since tuff is a limited resource, it is crucial to find suitable protective agents that prolong the life-cycle of tuff stone to preserve historical buildings

To favourably influence water absorption, effective porosity, and the pore structure of tuff stone, a thorough impregnation of the stone with the protective agent is desirable. This can be achieved by the application of silica sol products, which are dispersions of colloidal amorphous silicon dioxide particles. The small particle sizes (between 10 and 100 nm) facilitate a high penetration depth. Despite of the promising results of several studies, colloidal silicas are rarely used as protective agents for tuff stone in the restauration practice [3; 4]. This may be due to the lack of long-term experiences with these materials. Furthermore, the performance of protective agents is closely related to the pore structure and chemical and mineralogical composition of the rock [5; 6]. To understand these interactions, further research is needed.

The aim of a current research project is to study the application of colloidal silica as protective agent for Weiberner tuff. In first tests, penetration depth and changes in the pore structure are analyzed. Furthermore, the influence of the treatment on the hygric and mechanical properties and on the durability of the stone is studied. The new data will contribute to a better understanding of tuff stone deterioration and conservation.

 

[1] Wedekind et al. (2013) Environ. Earth Sci. 69. [2] Pötzl et al. (2018) Environ. Earth Sci. 77. [3] Iucolano et al. (2019) Contr. Build. Mater. 202. [4] Zornoza-Indart & Lopez-Arce (2016) J. Cult. Herit. 18. [5] Török et al. (2007) Geol. Soc. London, Spec. Publ. 271. [6] Stück et al. (2008) Environ. Geol. 56.

How to cite: Stuff, M., Rübner, K., Prinz, C., Rische, N., Chronz, M., and Kühne, H.-C.: Weathering and conservation of tuff stone , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18178, https://doi.org/10.5194/egusphere-egu2020-18178, 2020.

EGU2020-7524 | Displays | ERE5.1

Metakaolin geopolymers applied in the conservation of tile facades: a Portuguese case study

Fernando Rocha, Sara Moutinho, Cristiana Costa, Slavka Andrejkovičová, Luis Mariz, Cristina Sequeira, Denise Terroso, and Ana Velosa

The possibility of using geopolymers to fill gaps/lacunae in glazed ceramic tiles (azulejos) has been studied. Since the 15th century, glazed ceramic tiles are characteristic elements of the Portuguese architectural heritage and their use as external rendering elements has made them prone to degradation. On the other hand, civil construction is a sector with a high consumption of natural resources and CO2 emissions. In order to respond a necessary increase of sustainability in conservation/restoration processes, it is important to create/use sustainable repair materials that also ensure compatibility and durability of interventions. Geopolymers were studied as a potential sustainable and compatible repair material. Two commercial metakaolins ARGICAL-M 1200S and ARGICAL-M 1000 were used as precursors in geopolymer pastes and tested. The purpose of this research was to assess the potential of geopolymers in the restoration of the glazed ceramic tiles, both in the filling of gaps and the bonding of ceramic fragments. The physical, chemical and mineralogical analyses of these materials were performed. Additionally, in order to evaluate possible use in conservation interventions, tile lacunae filling, glazing reintegration and bonding of ceramic fragments were studied. Several tests were performed in order to analyse the compatibility and durability of the designed geopolymers and the ceramic/geopolymer system. The results suggest that the geopolymers had a better performance in the bonding of ceramic fragments and can have potential to be applied in the conservation and restoration of tile facades. Thus, as a general conclusion, it was possible to develop sustainable materials to apply in conservation of buildings facades.

How to cite: Rocha, F., Moutinho, S., Costa, C., Andrejkovičová, S., Mariz, L., Sequeira, C., Terroso, D., and Velosa, A.: Metakaolin geopolymers applied in the conservation of tile facades: a Portuguese case study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7524, https://doi.org/10.5194/egusphere-egu2020-7524, 2020.

The mechanical behavior of a natural stone ventilated facade is inevitably based on the correct execution of both anchoring elements, stone cladding and enclosure support, either with brick masonry walls or reinforced concrete walls. In the case studied in the present work, the origin of the damages on the facade of a building located in Lisbon has been analyzed, where stone detachments were starting to occur. This enclosure is a ventilated facade cladded with Portuguese limestone Lioz slabs. Non-destructive borescope analysis of the metallic anchoring system employed was performed, as well as X-Ray fluorescence laboratory analysis (FRX) for chemical characterization of the anchoring material. Results obtained demonstrated the problem cause on the stone facade due to incorrect metallic anchoring selection and poor execution combined with stress corrosion effect, especially for slabs with larger dimensions.

How to cite: Pires de Almeida Ribeiro, V.: Durability of a ventilated stone facade: A case study of a limestone facade affected by the corrosion of the anchorage system , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3755, https://doi.org/10.5194/egusphere-egu2020-3755, 2020.

Rabat, the capital of the Moroccan Kingdom, listed as a UNESCO World Heritage Site in 2012, has several historic monuments testifying its diversity and richness in tangible and intangible heritage, cultural richness, architectural diversity that perpetuates the different dynasties that are succeeded over time on this Kingdom.
The Chellah monument testifies to this diversity by including within its walls a variety of civilizations.
This special monument by its architecture, its history, its situation in the city of Rabat, knows physical and chemical degradation due to its location and the peculiarity of its building materials as well as the techniques used for the construction or for the rehabilitation.
In this work we have tried to decipher these causes and to quantify these degradations by the petrographic, mineralogical, geotechnical and chemical identifications of the products of the alteration, via laboratory analyzes such as the scanning electron microscope equipped with the EDX system, the diffraction X-ray ,fluorescence and  particle size analysis. This is to optimize the choice of alternative materials, while taking into account all the multidisciplinary scientific mechanisms and processes necessary for a better protection of the built material heritage that constitutes a collective memory of this country.
 
 
 

How to cite: Belhaj, S., Jaouda, I., Souidi, H., and Aqil, M.: Chemical and geotechnical analysis of the mortar and rammed earth from merinid walls of the Morrocan historical monument Chellah-Rabat for detection of alteration products and the origin of the original materials used., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-837, https://doi.org/10.5194/egusphere-egu2020-837, 2020.

Over the past few decades, the construction industry has focused on sustainable, environmentally friendly and easily recyclable materials. The objective of this work is to characterize and enhance the thermal conductivity, mechanical strength and setting time of a composite material based on plaster and lime. This material is designed for use in plasters.

Two types of gypsum are studied, the first one belongs to the Safi basin, the second one characterizes the High Atlas of Marrakech and precisely Douar Tafza. Geologically speaking, the two sites have many similarities. They are characterized by a Meso-Cenozoic age coverage covering a deformed Paleozoic age basement.

The characterization of the plaster's raw material, gypsum, was necessary to determine its physical and geotechnical properties, mineralogy, thermal behaviour and microscopic structure. Several analyses have been developed such as: pycnometer density measurement, X-ray diffraction, infrared spectroscopy and scanning electron microscopy.

We made samples, of standardized dimensions, of two mixtures based on the two types of plaster reinforced by the addition of two types of lime from different localities. The latter are from Marrakech and the Agadir region. The water/plaster mass ratio was set at 0.75 and the addition of lime was achieved by increasing its percentage in slices by 12.5% and up to 50%.

The reinforcement of plaster with lime has enhanced its thermal and mechanical properties and setting time. The measurements show that the addition of lime has reduced the thermal conductivity and increased the mechanical strength of both types of plaster. In addition, following the addition of lime, the setting time has decreased and the basicity of the material has increased. Noting that the intrinsic properties of the raw material influence the mechanical and thermal properties of the material.

Keywords:   plaster, enhancement, properties, mechanical, thermal, Morocco

How to cite: baba, I., Ibnoussina, M., and Witam, O.: Identification and enhancement of the thermal and mechanical properties of two types of plasters successively derived from gypsum: from the Safi basin and the High Atlas of Marrakech, Morocco, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-886, https://doi.org/10.5194/egusphere-egu2020-886, 2020.

EGU2020-7808 | Displays | ERE5.1

Mobile processing and use of short-transported aggregates

Svein Willy Danielsen and Tero Onnela

Mobile processing and use of short-transported aggregates

 

Svein Willy Danielsen1) and Tero Onnela2)

 

1) Geomaterials Consultant

2) Metso Minerals

 

Aggregates are major constituents in construction, the global request for which approaches some 22 billion tonnes per year. Some major challenges follow; first of all the dependency on geological conditions and the availability of resources; secondly the traffic, emissions and energy use connected with transportation; thirdly the technology of utilising resources with a variety of properties to meet user requirements; and finally – getting more awareness – the land use conflicts and environmental impact of the aggregate and quarrying industry, and the need for making these activities sustainable. 

Geological resources are non-renewable, which e.g. can be seen in the rapid depletion of natural sand/gravel deposits: Most development in the aggregate sector is now focusing on crushed/manufactured materials. This causes increasing awareness along with environmental impact; conflicts of interest concerning land-use; sustainability in mass balance; and not least – increasing transport distances required to get the materials to the places of use.

The principle of a Best Available Concept (BAC) for aggregate production and use was introduced by Danielsen and Kuznetsova (2016 Geological Society Special Publication 416, pp 50-70), working with four essential phases: Inventory and planning, Quarrying and production, Use of aggregates, and Reclamation of mined-out areas. Important in such a concept is the use of novel LCC and LCA tools to enable the calculation of environmental and economic consequences of decisions.

The development of concepts and technologies to utilise local aggregates on a short-travel basis, is an important part of this. A major Norwegian research project Local Use of Rock Materials, lead by SINTEF and sponsored by industry and the Research Council, has just been concluded. One aim of such a development was to obtain production processes on mobile platforms to offer on-the-run solutions that can greatly reduce the need for transport to and from site, make more tolerant user techniques of excavated or secondary rock materials, and not least, contribute to a significant improvement of mass balance. A comprehensive report on this theme has been prepared by the present authors.

Aggregates should be prioritized based on geological conditions in a bottom-up concept. This means that when considering local and/or short-travelled alternatives, the design and engineering solution should be based on the aggregates available – not the other way around. The geological differences and the often unpredictable variations are clearly among the major challenges for a short-travelled solution. The report highlights the aggregate technology triangle in order to see the geology – production – application interconnection, for the creation of good solutions

The set of novel processing technologies available, present the opportunities to transform theoretical knowledge into practical aggregate production. Especially, the portable processing equipment and the novel technology for crushing and sorting opens for solutions to produce purpose adapted, local/short-travelled aggregates. The report suggests processing examples for different user-purpose. Several flow-sheets for mobile processing of different kinds of product are presented and discussed.

How to cite: Danielsen, S. W. and Onnela, T.: Mobile processing and use of short-transported aggregates , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7808, https://doi.org/10.5194/egusphere-egu2020-7808, 2020.

EGU2020-5137 | Displays | ERE5.1

Production of upgraded recycled aggregates from construction and demolition waste for replacement of primary sand in cement mortars

Michael Galetakis, Athanasia Soultana, and Theodoros Daskalakis

Waste concrete is the most predominant constituent material among construction and demolition waste. Recycling of this material could minimize landfilled waste and mineral resources depletion. This study investigates, in laboratory scale, the production of upgraded recycled concrete aggregates, suitable for the replacement of primary (crushed limestone sand) used in cement mortars, by means of selective crushing and autogenous grinding. These particle size reduction techniques, compared to traditional crushing/grinding, have the potential to remove the brittle cement paste from the aggregates, thus significantly improving their quality. The granulometry, the density, the water absorption (EN 13755) and the flow coefficient (EN 933-6) of the produced upgraded sand was determined and compared to crushed limestone sand. Subsequently, cement mortar specimens were manufactured using upgraded aggregates for total replacement of crushed limestone sand. Specimens were tested for their compressive and flexural strength (EN 196-1), density and water absorption. Results indicated that the upgraded recycled sand produced through the selective crushing and autogenous grinding processes had improved properties compared to the one produced by conventional crushing processes (flexural and compressive strength of cement mortar specimens were increased by 29% and 7%, respectively). However, the quality of the upgraded sand is lower than that of the primary crushed limestone. To further explore the issue, it is planned to investigate in more detail the process of autogenous grinding and to investigate the use of other selective aggregate-cement paste liberation technologies.

How to cite: Galetakis, M., Soultana, A., and Daskalakis, T.: Production of upgraded recycled aggregates from construction and demolition waste for replacement of primary sand in cement mortars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5137, https://doi.org/10.5194/egusphere-egu2020-5137, 2020.

EGU2020-1460 | Displays | ERE5.1

An investigation into the potential uses of the waste aggregate stockpile at Belgard quarry.

Ciara Bannon

EGU2020-17649 | Displays | ERE5.1

Environmental managing of bottom ashes from municipal thermovalorization waste for civil applications, as a function of particle size, based on steam washing

Caterina Caviglia, Enrico Destefanis, Davide Bernasconi, Linda Pastero, Giorgia Confalonieri, Ingrid Corazzari, Francesco Turci, Costanza Bonadiman, Renzo Tassinari, and Alessandro Pavese

Nowadays, the production of constructional materials requires raw materials obtained through extractive activities that often imply different environmental impacts. In a perspective of a growing sensitivity towards a responsible use of natural resources the attention to materials coming from waste is focused. The waste from the municipal thermovalorization plants can be suitable for this applications, and after moderate and sustainable treatments, can find a role of raw material-second in the construction of works, reducing the need to find additional natural resources and related problems for disposal or storage. The present study aims to explore the possibility of promoting inertization (i.e. reducing the BA’s release in water of environmentally dangerous chemical species below the legal thresholds) of as large a fraction of BA as possible, using ashes from one of the municipal waste incineration plants of Northern Italy, and exploiting byproducts of the incineration cycle, i.e. the spared steam from turbines, which produce electricity, and carbon dioxide from combustion fumes. The treatments discussed are as a function of the particle size (s).  BA are partitioned into three main classes, determined by previous studies s ≥ 4.75, 4.75 > s ≥ 1, s < 1 mm; %. The BA fraction with 4.75 > s ≥ 1 mm was further divided into two portions to optimize the steam washing process: 4.75 > s ≥ 2 mm and  2 > s ≥ 1 mm. BA with s > 4.75 mm are treated with steam washing only. In fact, although they do not contain high concentrations of heavy metals, they largely surpass the Italian legislation thresholds related to the occurrence of chlorides and sulfates. Steam is generally available from modern incineration plants in a considerable amount, and it is more effective than water in removing a variety of impurities/low-crystallinity fragments from the surface of coarse grains. Inertization of BA with 4.75 > s ≥ 1 is investigated by means of both steam washing and accelerated carbonation, to optimize the combination of these methods and expand as much as possible the s-range that requires steam washing only.  As to the BA fraction with s < 1 mm, whose heavy metals content is likely larger than elsewhere, steam washing is of difficult application and therefore we resort to accelerated carbonation.

How to cite: Caviglia, C., Destefanis, E., Bernasconi, D., Pastero, L., Confalonieri, G., Corazzari, I., Turci, F., Bonadiman, C., Tassinari, R., and Pavese, A.: Environmental managing of bottom ashes from municipal thermovalorization waste for civil applications, as a function of particle size, based on steam washing, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17649, https://doi.org/10.5194/egusphere-egu2020-17649, 2020.

EGU2020-10013 | Displays | ERE5.1

Role of alkanolamines in ordinary and alternative cement systems

Ludovico Mascarin, Luca Valentini, Maria Chiara Dalconi, Enrico Garbin, and Gilberto Artioli

Ordinary cement resulting from the reaction of a calcium aluminosilicate-rich powder plus water works as binding matrix in modern concrete. The design of alternative binders is currently a global challenge in order to reduce the environmental footprint associated to the ordinary cement production. Alkali-activated calcined clay materials (AAccMs) represent a class of sustainable binders made of the blending of a concentrated alkaline solution and a solid fraction with thermally treated phyllosilicates. Metakaolin produced by the heat treatment at temperatures between 550-900°C of kaolinite, has long fascinated the scientific community for its high reactivity at high-pH stage. However, the higher costs of commercial metakaolin push towards the use of locally available low-purity kaolinitic soils, such as laterite covers, as potential raw materials to produce low-CO2 cements with the benefit of reducing the cost of feedstock transportation.

The work is focused on the role of triethanolamine (TEA) and triisopropanolamine (TIPA) on the reaction kinetics of ordinary cement pastes and AAccMs, the latter with different aluminosilicate reactive fraction and degree of purity. TEA and TIPA are tertiary alkanolamines with a developed molecular structure. It has been assessed that low equal dosages of alkanolamines introduced in advance to the mixing water for cement hydration can act on the setting time and the degree of cement reaction. These chemical compounds, and above all TIPA, are recognized as iron-chelating agents that can increase the dissolution rate of ferric ions from the ferroaluminate phase of cement and promote their complexation. Moreover, alkanolamines can also form water-soluble calcium-complexes that may influence the hydration kinetics of calcium-silicate phases and the precipitation of hydrates in the binder microstructure.

The raw and the reacted materials are characterized by X-ray diffraction (XRD) and the kinetic pathways are followed with the aid of a semi-adiabatic calorimetry. The dissolution-precipitation steps of hydration in aqueous and alkaline solutions are subsequently simulated. Ordinary cement is used to clarify the role of alkanolamines as hardening accelerators. Afterwards, the kinetics of alkali-based pastes of high-purity metakaolin and a Fe-rich laterite, both blended with waste marble powder, are compared with the aim of assessing the formation of calcium-complexes in solution and any change in the kinetics due to the presence of iron in the raw material. Mechanical strength tests are performed to make clear the beneficial or detrimental effect of TEA and TIPA on the materials.

How to cite: Mascarin, L., Valentini, L., Dalconi, M. C., Garbin, E., and Artioli, G.: Role of alkanolamines in ordinary and alternative cement systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10013, https://doi.org/10.5194/egusphere-egu2020-10013, 2020.

The consumption of natural resources in various industrial sectors has caused significant environmental issues to the atmosphere through emission and energy cost due to the extraction and transportation of the materials, along with the availability and long-term damage to the natural resources. In order to address this issue, various solutions have been provided to reduce the amount of consumed natural resources by replacing them with alternative materials such as plastic waste and plastic, as a burden to the environment, is one of those materials being well explored by other researchers due to its worldwide applications and destructive impacts on nature.

The industrial sectors, as massive consumers of natural resources and producers of plastic waste, have shown a continuous responsibility towards innovative alternatives for natural resources. In this regard, plastic materials such as Polyvinyl, Polystyrene, Polyethylene and Polypropylene have been investigated to replace coarse and fine aggregates in the construction without compromising the performance of the concrete mix.

This study aims to investigate the influence of Polypropylene as a fine aggregate replacement on the compressive and tensile strength of concrete cylinder samples after 28 days of curing and assess the impact of temperature on thermal properties of the 28 days cured samples.

How to cite: Keihani, R. and Bahadori-Jahromi, A.: Investigate the influence of Polypropylene as fine Aggregate Replacement on the mechanical and thermal properties of the concrete mix , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21782, https://doi.org/10.5194/egusphere-egu2020-21782, 2020.

EGU2020-13887 | Displays | ERE5.1

Degradation of concrete with glass enriched recycled aggregate used to flooring an industrial warehouse in Italy

Elena Marrocchino, Negar Eftekhari, and Carmela Vaccaro

This research investigates as chemical and mineralogical properties can affect degradation of concrete, made using secondary aggregates derived from recycled, in the enforcement of Waste Framework Directive (WFD) 2008/98/EC. High volumes of C&D require the use of waste in various productive contexts. The utilisation of secondary materials derived from CDW recycling in flooring of industrial warehouse can reduce the environmental impacts of quarrying extractions. In recent years, the use of waste in the packaging of mortars and conglomerates has been increased and many companies offer the incorporation of waste glass as aggregate for concrete and mortars. There is still scientific debates on the opportunity to use glass related to the influence on workability and there are some concerns on the durability and resistance to degradation of products made with non-natural aggregates in conditions of interaction with alkali-rich waters.

In this work mineralogical-petrographical analyses have been carried out on sample and have shown that:

- use of glass influences compaction factors, therefore there is an increase in the air content also due to the involvement of numerous small particles. This produces high macroscopic and nanometric porosity, observed both on thin sections microscope observations and on SEM-EDSanalyses, which affects compressive, tensile and flexural strength of mortars and concrete in proportion to the content of waste glass used.

- microcracks in glass aggregates, produced by crushing, increase aggregate water interaction surface, so it tends to degrade more easily by hydrolysis, moreover the greater permeability to air and water accelerates carbonation processes.

- smooth surface of the waste glass decreases the adhesion force between glass surface cement.

- addition of waste glass to natural aggregates produces an improvement in workability due to the non-absorbent nature of the glass.

- In the short time inclusion of glass aggregates effectively improves the surface resistivity and the attack on sulphate but in the long time a secondary porosity for hydrolysis intervenes and the resistance decreased, and the carbonation rate increases.

- contraction from drying of the concrete decreases with the content of glass aggregates increasing, but subsequently the swellings by hydrolysis can produce a secondary porosity giving an intimate and widespread fracturing of the matrix

Petrographical both on thin sections and on crushed samples observation and SEM-EDS microanalysis have shown that degradation is due to the use of crushed natural aggregate mixed with recycling aggregate rich in common glass. This degradation has provided that alkaline elements interact with cement and with siliceous aggregates of the screed. It has been also noted that degradation is accelerated by the widespread presence of sulphur, sometimes in high concentrations and due to the use of recycled material, and the presence of iron. Degradation differences depend on a heterogeneous distribution of the C&D waste aggregate, so in the areas where it is less abundant, the phenomenon is less striking.

How to cite: Marrocchino, E., Eftekhari, N., and Vaccaro, C.: Degradation of concrete with glass enriched recycled aggregate used to flooring an industrial warehouse in Italy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13887, https://doi.org/10.5194/egusphere-egu2020-13887, 2020.

One of the most popular and intensively extracted building stones in Japan is a Miocene dacite-rhyolite ignimbrite known as Oya-ishi, quarried nearby the city of Utsunomiya (Tochigi). Traces of its historical usage in the last 1,500 years survive in vernacular architecture, construction, rock-cut and relief sculpture, but large-scale exploitation commenced only in the Edo period (i.e., from the 17th century), an epoch of economic growth and flourishing arts and culture. Among the over 200 underground quarries in the region, few are still active, the others abandoned or converted into geoheritage and tourist attractions (e.g., History Museum, Heiwa Kannon monument, Keikan Park). Salt weathering is one of the decay aspects of Oya stone jeopardizing the preservation of those sites of historical and geological interest and, indirectly, visitor safety. The efflorescences on the tuff quarry walls turn out to be composed of sulfates, namely gypsum, mirabilite, and thenardite, their crystallization being controlled by the relevant microenvironmental conditions. In the extremely humid underground spaces, the phases having a very high deliquescence relative humidity are stable: gypsum is essentially ubiquitous, even in the deepest quarry levels, the most environmentally isolated; mirabilite needs a slightly dryer environment, so is observable in the middle levels or semi-underground quarries; thenardite requires further dryer conditions, and is mainly detected in the open air. The mechanisms of formation of these efflorescences are still under investigation: the classic minero-petrographic and geochemical characterization of the rock and its weathering phases is being supported by a microclimatic monitoring in different sites and seasons, and the chemical analysis of rainwater and groundwater. The research direction is aimed at the identification of the environmental and lithological constraints on the salt weathering of Oya tuff, that is: the spatial and temporal variability of relative humidity, and its influence on the cycles of salt crystallization/dissolution and the resulting mechanical stresses; the chemical driving forces, related to the rock mineralogy (zeolites, feldspar alteration, etc.) and water quality.

How to cite: Germinario, L. and Oguchi, C. T.: Salt weathering and geoheritage - Sulfate efflorescences in historical underground quarries of tuff, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-410, https://doi.org/10.5194/egusphere-egu2020-410, 2020.

EGU2020-9774 | Displays | ERE5.1

An attempt of SfM photogrammetry to narrow and dark underground building heritage

Chiaki Oguchi, Kisara Shimizu, Yasuhiko Tamura, Yuichi Hayakawa, and Takuro Ogura

The 3D models creating by SfM (Structure-from-Motion) photogrammetry became one of the important and convenient methods for any kinds of objects on geomorphology, geoheritage, or geoarchaeological fields. These objects are landforms, monuments, buildings, relics and so on. In order to evaluate these objects, it is necessary to collect morphological characteristics, and then proceeding to decide investigating points or areas of these materials.

The progress of this methods developed significantly, however, there have been still remained difficulties depending on the objects. For example, it is difficult to create 3D models that the object is too flat, too dark, and/or any restricts of combination of target size and focusing distances. The present study attempts to these difficulties by targeting to narrow and dark underground space. The investigating object is an archaeological man-made cave, called Taya Cave, in central Japan. It was excavated in 13 century originally and used as study areas for Buddhists by making Buddhism bas-reliefs. The cave has a total length of 570 m underground passage with a three-layer structure. The cave also has several domes connected by narrow paths. The present study tried to make a 3D model of this complicated, dark and narrow cave by SfM photogrammetry. In order to concur to make 3D models for the whole area of the cave, it is useful making chunks; separating several areas of simple morphology and then compiled. When facing narrow path, it is better to take photographs not by perpendicularly but by inclinedly. Furthermore, it is important to use strong light with attach to camera. After obtained the image data of the whole cave, the accuracy of the created model was evaluated. The results were that the accuracy of horizontal distances are higher than that of vertical distances.

How to cite: Oguchi, C., Shimizu, K., Tamura, Y., Hayakawa, Y., and Ogura, T.: An attempt of SfM photogrammetry to narrow and dark underground building heritage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9774, https://doi.org/10.5194/egusphere-egu2020-9774, 2020.

In Morocco, no measures have been taken to manage residual waste from operational or abandoned mining and quarries sites.

Indeed, significant quantities of mine waste, composed of concentrator residues and sterile waste, have been abandoned after the closure of operations without any effective management or rehabilitation planning.

These residues could have harmful impacts on the environment: soil and water pollution, destruction or disturbance of natural habitats, visual impact on the countryside...

The valorization and sustainable management of mining waste appear to be adequate solutions to major environmental problems. The construction sector can be a profitable sector to absorb chemically stable mining waste.

The objective of this research work is to study the feasibility of recycling waste from the abandoned Kettara mine (Morocco) and gypsum waste rock in Sidi Tijji (Morocco) as raw materials in construction materials.

The study consists first of a geological characterization and then a characterization of the physical, chemical and mineralogical properties of the residues, followed by an evaluation of the mechanical properties of the composite mixtures based on the chemically stable residues.

The Kettara mine is located in the Jbilet Central Mountains, 30 km northwest of Marrakech. Geologically, the pyrrhotite district of Kettara corresponds to the outcrop area of the volcano-sedimentary series of Saghlef shales. For the gypsum quarry at Sidi Tijji, which is part of the Safi basin, characterized by Jurassic outcrops essentially formed by gypsum and carbonate formations.

Mineralogical and chemical analysis have shown that these waste products are still rich in minerals such as the waste from the Kettara mine; the FeO3 concentrated amounts to 55.6%. In addition, gypsum waste rock represents a concentration of 28.9% CaO. Therefore, a low water content for the majority of samples.

Adapting to the principles of integrated recovery and management of mining and quarry waste requires a cultural change within the industry, but also in the ministries concerned.

Keywords: Valorization, mine waste, mines and quarries, construction materials.

How to cite: Bouiji, A., witam, O., and Ibnoussina, M.: Characterization and valorization of the waste from the abandoned Kettara mine and the gypsum quarry in Sidi Tijji (Marrakech-Safi Region, Morocco)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-887, https://doi.org/10.5194/egusphere-egu2020-887, 2020.

EGU2020-1231 | Displays | ERE5.1

High Resolution 3D modelling of Cylinder shape bodies applied to 1000 ancient BC columns

Giuseppe Casula, Silvana Fais, Francesco Cuccuru, Maria Giovanna Bianchi, and Paola Ligas

A multi-technique high resolution 3D modelling is described here aimed at the investigation of the state of conservation of carbonate columns of the 1000 BC ancient church of Buon Camino located in the homonymous district of the town of Cagliari (Italy).

The integrated application of different Non-Destructive Testing (NDT) diagnostic methods is of paramount importance to locate damaged parts of the building material of artefacts of historical buildings and to plan their restoration.

In this study a multi-step procedure was applied starting with a high resolution 3D modelling performed with the aid of Structure from Motion (SfM) Photogrammetry and Terrestrial Laser Scanner (TLS) methodologies. For this delicate task we operated simultaneously a Nikon D-5300 digital Reflex 24.2 Mega pixel Camera and a Leica HDS-6200 Terrestrial Laser Scanner. Subsequently, starting from the information detected with the above methods deeper material diagnostics was performed by means of high resolution 3D ultrasonic tomography aimed at the capillary definition of the elastic properties in the inner parts of the building materials. Measurements of longitudinal wave velocity from ultrasonic data were performed using the transmission method, namely two piezoelectric transducers coupled on the opposite sides of the investigated columns. The ultrasonic data acquisition was planned designing an optimal survey and providing a very good spatial coverage of the investigated columns. The columns were then criss-crossed by a large number of ray paths forming a dense 3D net. The SIRT (Simultaneous Iterative Reconstruction Tomography) algorithm was used to produce the 3D rendering of the velocity distribution inside the investigated columns. With this method the damaged parts were located and it was possible to distinguish them from the unaltered areas. The information on the superficial material conditions obtained by SfM and TLS techniques were compared and integrated with the information of the inner materials obtained by 3D ultrasonic tomography.

The results of the above non invasive geophysical techniques have been interpreted in the light of the different textural and petrophysical features of the study carbonate building materials. The study of the main textural features, such as the relationship between bioclasts, carbonate matrix, or that of the cement and petrophysical characteristics such as the nature and distribution of porosity were found to be of fundamental importance in the interpretation of the geophysical data (e.g. TLS reflectance and longitudinal acoustic wave propagation). Therefore a detailed analysis of the textures and pore microstructure were carried out from petrographic thin-sections in Optical and Scanning Electron Microscopy (OM/SEM). The final result of our multi-step-technique integrated methodology is a sophisticated 3D model with a high resolution 3D image representing the internal and external parts of the investigated columns in order to account for their static load resistance and possibly plan their conservation and restoration. The described procedure can also be applied to other cases in which a diagnosis is needed of the state of conservation of the variously shaped, layered-stones and composed artefacts typical of ancient historical buildings.

Key words: 3D Modelling, 3D Ultrasonic Tomography, Terrestrial Laser Scanner, SfM Photogrammetry, Non-Destructive Testing, Diagnostic, Ancient Columns, Stones

How to cite: Casula, G., Fais, S., Cuccuru, F., Bianchi, M. G., and Ligas, P.: High Resolution 3D modelling of Cylinder shape bodies applied to 1000 ancient BC columns, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1231, https://doi.org/10.5194/egusphere-egu2020-1231, 2020.

Decision on suitability of rocks for production of crushed stone and their use in specific constructional activities relies on series of empirically-designed tests which partly simulate certain degradation forces acting during the service of aggregates. Tests for integrity of crushed stone particles subjected to mechanical forces employ several approaches simulating abrasion, attrition, and/or crushing; these can thus be generally designated as technological-mechanical performance (TMP) tests. Design of these tests has nothing to do with testing of mechanical properties viewed as fundamental physical property. However, numerous authors attempted to correlate certain mechanical properties (specifically uniaxial compressive strength data) with TMP of crushed stone source rocks. Unfortunately, relatively low correlation has been generally achieved.

In the recent study, this approach is re-examined by using not only ultimate strength data, but also knowledge on deformational process and on its energetic parameters. The results of laboratory experiments show, that some of the obtained data exhibit much tighter correlation; however, one has be very careful in selection of proper parameters. Thorough understanding of damage mechanisms of crushed stone particles (i.e. mechanisms of their wear and breakage during service life) makes critical part of this evaluation process.

How to cite: Prikryl, R.: Relationship of mechanical properties of crushed stone source rocks to their technological-mechanical performance, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7835, https://doi.org/10.5194/egusphere-egu2020-7835, 2020.

Degree of size reduction of selected crushed-stone source rocks and its relationship to technological-mechanical performance parameters

 

Kateřina Krutilová (1), Richard Přikryl (2)

 

(1) Stone testing laboratory Ltd., Hořice v Podkrkonoší, Czech Republic

(2) Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43, Prague 2, Czech Republic

 

Particle size reduction (PSR) is one of the principal processing methods employed in extractive industry including production of crushed stone aggregates. The purpose of particle size reduction is production of certain size fractions which are directly applicable for final uses or necessary for further industrial activities. On industrial scale, crushing of rocks for crushed stone production is commonly performed in 2-3 successive steps (stages). The conditions of crushing in these individual steps is selected in order to reach lower reduction ratio, thus facilitating production of particles with favourable geometry. Conditions of crushing are influenced by numerous factors, of which only part was thoroughly investigated. In the recent study, we attempt to correlate knowledge on PSR behaviour of various petrographic types with other technological-mechanical performance parameters (e.g. Los Angeles attrition value, Nordic abrasion test, aggregate crushing value) and/or physical / mechanical properties of aggregate source rocks (specifically volcanic rocks of variable composition, ages, and properties). PSR behaviour obtained by experimental laboratory crushing (one-step process) is reported as degree of size reduction and reduction ratio. 

How to cite: Krutilová, K. and Přikryl, R.: Degree of size reduction of selected crushed-stone source rocks and its relationship to technological-mechanical performance parameters , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13464, https://doi.org/10.5194/egusphere-egu2020-13464, 2020.

Feldspar-rich leucogranite formed by metasomatic / hydrothermal alteration of original granite makes one of the key resources of feldspar raw material for ceramic / glass industries in the Czech Republic. Studied material is composed by prevailing albite and quartz accompanied with small amounts of minor / accessory phases which represent the major harmful components responsible for colour changes in final product. To improve quality of marketed feldspar, part of exploited raw material started to be processed by using magnetic separation in recent years.

To increase efficiency of processing, trials on usage of additional processing / separation methods have been applied in recent study. The approach involves three successive steps: (1) laboratory, (2) small-scale, and (3) full-scale separation schemes.

Concerning laboratory separation, several grams of input material were processed by using magnetic separation and gravity separation. This helped in separation of major harmful components (Fe-, Mn-, Ti-rich phases partly with complex mineralogical binding with Nb–Ta, Li-micas, and apatite).

Small-scale separation as a second step attempted to find optimized processing flow-chart usable for separation of some potentially interesting phases (Li-rich and Nb-Ta minerals). Control of the best granulometry presented one of the challenges. By studying various separation techniques, combination of dry magnetic separation and air gravity concentrating table proved to be very effective.

During full-scale separation several tons of input material were processed by magnetic separation followed by air-gravity concentrating table. The chemical composition of separation end-products was tested by XRF. Properties important for ceramic / glass industry (specifically experimental burning and colorimetric measurements) were checked as well. Such an approach allowed for realistic evaluation of the beneficiation flow-chart prior to its implementation on the industrial scale of processing of feldspar raw material.

How to cite: Vrbický, T. and Přikryl, R.: Processing waste from feldspar raw material as a potential source of certain strategic elements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9326, https://doi.org/10.5194/egusphere-egu2020-9326, 2020.

EGU2020-19023 | Displays | ERE5.1

Sensors applied in the detection of physical changes at heritage buildings

Ákos Török and Ákos Antal

Heritage buildings are susceptible to environmental impacts, and many of the stone structures show intense damage due to weathering, soil instability or improper use. The detection of changes has primary importance in the understanding of deterioration processes, and it provides essential information for the preservation of these structures. The application of destructive techniques to assess the condition of the materials of these heritage structures are not feasible and in most cases, not permitted. Consequently, monitoring of the health of the construction material and the structure require techniques that are not destructive and automatically collects data from the sites. The study provides an overview of sensors that could be applied in monitoring of the conditions of cultural heritage structures. From the methods of placing sensors at sites to available data collection system – the entire process will be overviewed. Applications of spectroscopic sensors for in situ and real-time analysis of critical colorimetric parameters of building materials will be presented. Application of artificial intelligence-based data processing in the prediction of material degradation is also discussed. Optical detectors of remote sensing techniques applied in monitoring of heritage buildings are also addressed. The financial support of National Research, Development and Innovation (NKFI) Fund (K 116532) is appreciated.

How to cite: Török, Á. and Antal, Á.: Sensors applied in the detection of physical changes at heritage buildings, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19023, https://doi.org/10.5194/egusphere-egu2020-19023, 2020.

EGU2020-18766 | Displays | ERE5.1

Damaging effect of salt crystallization on highly porous limestone from Hungary

Nikoletta Rozgonyi-Boissinot and Mohammad Ali Khodabandeh

One of the most important weathering processes on stone-built monuments is the crystallization of salts. Since the transport material of these substances is water, the porous rock types are particularly affected. In Hungary many monuments and historic buildings have been constructed from oolithic Miocene limestone. So in this study, the effect of salt crystallization on the physical and mechanical properties of high porous limestone has been investigated. Samples were obtained from Sóskút (near to Budapest, the capital city of Hungary).

At first the petrophysical properties of the stone were determined. The porosity of the investigated stone type was 26-34 V/V%, the uniaxial compressive strength (4-5 MPa) and the Brazilian tensile strength (0,4-0,5 MPa) were very low. A special proper of this rock type is the large-pore system (2-3mm) between the ooid fragments.

Sodium chloride (NaCl) and sodium sulphate (Na2SO4) were used to investigate the effect of salt crystallization. Cylindrical rock samples were exposed to salt solutions of 14 m/m% Na2SO4 (MSZ EN 12370) and 5% NaCl solution (sea water salt content). After 15 salted water saturation- drying cycles the changes of mineralogical and petrophysical properties and indirect tensile strength of the samples were investigated. The damages on the pore walls were determined with scanning electron microscope (SEM) and the building of scaling layers on the stone surfaces were investigated with optical microscope.

How to cite: Rozgonyi-Boissinot, N. and Khodabandeh, M. A.: Damaging effect of salt crystallization on highly porous limestone from Hungary, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18766, https://doi.org/10.5194/egusphere-egu2020-18766, 2020.

EGU2020-10462 | Displays | ERE5.1

Modelling of seismicity-induced cracking of stone columns using discrete-element-method (DEM), a case study of Eufrasius cathedral, Porec, Croatia

Ali Besharatinezhad, Ákos Török, Mohammad Al-Tawalbeh, and Miklós Kázmér

The Eufrasius Cathedral of Poreč in Istria Peninsula, Croatia, was built in the 6th century, The nave collapsed in parts due to the AD 1440 earthquake. Nave and aisles are supported by 18 monolithic columns of Proconnesian marble. Seventeen of the columns bear various fractures, forming two groups: (1) axis-parallel fractures and (2) oblique fractures. Azimuths of dip directions of oblique fractures indicate N-S shaking.

In this study, the fracture development and cracking of a stone column was modelled using computer code. To model the current fracture pattern and to link it to seismic activity a Lagrangian analysis of continua in three dimensions (FLAC3D) is employed to reveal the non-linear behaviour of the stone column. A 3-Dimensional model based on discrete-element-method (DEM) has been created to study the failure process of the ancient stone column under static and dynamic loads. A combination of vertical and horizontal loads with a dynamic load due to the earthquake has been imposed horizontally. The influence of different parameters such as mechanical properties of rock, the magnitude of the earthquake were also assessed to observe their influence on the failure mechanism of rock. The DEM model was able to describe the observed crack pattern and it has proved the applicability of FLAC3D to describe failure mechanism of stone columns.

How to cite: Besharatinezhad, A., Török, Á., Al-Tawalbeh, M., and Kázmér, M.: Modelling of seismicity-induced cracking of stone columns using discrete-element-method (DEM), a case study of Eufrasius cathedral, Porec, Croatia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10462, https://doi.org/10.5194/egusphere-egu2020-10462, 2020.

EGU2020-18280 | Displays | ERE5.1

Cement render and mortar and their damages due to salt crystallization in the Holy Trinity Dominicans monastery in Cracow, Poland

Mariola Marszałek, Krzysztof Dudek, Adam Gaweł, and Jerzy Czerny

The presented investigations are focused on a part of the 13th century Church of the Holy Trinity Dominicans monastery in Cracow, Poland, and include the wall façade of the 17th century Myszkowski chapel. The chapel was probably designed by Santi Gucci Fiorentino and built by his workshop. Southern façade of the chapel is made of Tertiary limestone blocks that make characteristic rusticated wall. Lower part of the façade is covered with cement and the basement is made of irregular fragments of Jurassic limestone and Cretaceous sandstone partly replaced and bound with cement mortar. The façade revealed clear signs of damage ranging from dark gray soiling of the surface, scaling to efflorescences. The last ones – mainly on the border of limestone blocks and the cement in the part of the basement.

Laboratory tests included mineralogical, chemical and petrophysical analyses. Optical microscopy, scanning electron microscopy (SEM-EDS), micro-Raman spectroscopy and X-ray diffractometry (XRD) were used for analysing materials and deterioration products of the cement render and mortar. The petrophysical properties of the materials have been performed using mercury intrusion porosimetry. The secondary minerals detected include mainly gypsum CaSO4·2H2O, thenardite Na2SO4,  aphthitalite (Na,K)3Na(SO4)2, darapskite, Na3(SO4)(NO3)·H2O, nitre KNO3, nitratine NaNO3, ettringite Ca6Al2(SO4)3(OH)12·26H2O and monosulphite Ca4Al2O6SO3·11H2O. Lower blocks of the façade covered with cement contain chiefly gypsum, ettringite and monosulphite, cement from the basement – gypsum and nitre; while efflorescences – thenardite, aphthitalite, darapskite, nitre and nitratine. The origin of the salts have been discussed and the differences in their type have been associated with composition of the materials and their physicochemical properties.

This work has been financially supported by the AGH University of Science and Technology, statutory grant no. 16.16.140.315.

How to cite: Marszałek, M., Dudek, K., Gaweł, A., and Czerny, J.: Cement render and mortar and their damages due to salt crystallization in the Holy Trinity Dominicans monastery in Cracow, Poland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18280, https://doi.org/10.5194/egusphere-egu2020-18280, 2020.

For a long time, historical mortars were primarily associated with mortars based on calcium carbonate as the main binder phase. Recent publications show that considerable amounts of magnesium are often present in the binder of historical mortars, which is referred to the use of dolomite rock as raw material (Diekamp, ​​2009; Diekamp, ​​2014). A special feature are Roman and medieval dolomitic lime mortars with the addition of brick fragments as a pozzolanic component (Schidlowski, 2019).In order to characterize the phase formation in modern pozzolanic dolomitic lime mortars, mortar prisms based on dolomitic lime were produced with three different pozzolans (antique and modern brick dust and metakaolin). To draw comparisons with other binders, identical prisms based on calcite and magnesite were produced. These specimens were stored under different environmental conditions (60 % and 95 % relative humidity) and examined by X-ray diffraction and simultaneous thermal analysis after periods of 28, 90 and 180 days.

The results obtained so far show that the binder phases that have evolved in the mortars based on dolomitic lime are calcite, aragonite, portlandite, brucite and AFm phases. Aragonite is only found in traces in the samples with metakaolin. In contrast to the samples stored at 65 % relative humidity, the samples stored at 95 % relative humidity have lower calcite and higher contents of portlandite and AFm phases.

No significant differences in the amount of calcite and water-containing mineral phases (portlandite, brucite, hydrotalcite) can be found after 28, 90 and 180 days. It can be concluded that a large part of the reactions has already taken place after 28 days.

The present study is believed to be beneficial for a thorough understanding of the phase formations in dolomitic lime based mortars at different curing conditions.

How to cite: Schidlowski, M., Bader, T., and Diekamp, A.: Mineralogical investigations on pozzolanic dolomitic lime mortars to assess the phase development at different curing conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20057, https://doi.org/10.5194/egusphere-egu2020-20057, 2020.

EGU2020-18128 | Displays | ERE5.1

Characterization of historical inorganic binders and design of restorative materials - case study of the late Roman mosaic

Jonjaua Ranogajec, Snezana Vucetic, Maja Frankovic, and Helena Hirsenberger

The design of restorative mortars for historical buildings and artefacts is always a challenging task, with multiple requirements which have to be achieved and harmonized. Essentially, restorative mortars have to comply with chemical, mineralogical and mechanical compatibility criteria, which also include formation of contact zone, tensile strength, porosity and visual properties (colorimetric parameters). One of the successfully restored examples is the mosaic discovered broken in 2014 with severely disturbed positioning of fragments. The mosaic represents head of Medusa dated from Late Roman period and found at the archaeological site in Skelani, Bosnia and Herzegovina.

 

The case study presented in this abstract is a good practice example of collaboration between restoration and science which shortens the period for attaining relevant inputs and gives confidence to future restoration decisions. The investigation reviled that the mosaic bedding layer was of very good quality and has allowed fragments of various sizes to be preserved (tesselatum, nucleus and even rudus layer on some fragments). The objective of the restoration was to preserve remains of the original bedding layer and to connect and stabilize groups of individual fragments. The idea was to design compatible restoration mortar which will support the requirements for future mosaic presentation.

 

The characterization of historic inorganic binder samples, performed in the Laboratory for Materials in Cultural Heritage, Faculty of Technology, University of Novi Sad, provided invaluable information about the composition of mosaic bedding layers, their preparation, and moreover about degradation mechanisms in regard to centuries of its use and environmental conditions. It was reviled that the original inorganic binder is a lime based mortar with brick fragments imbedded. A strong bonding with preserved bedding layers of mosaic fragments and a set of specific compatibility objectives framed attempts to design compatible restorative mortar. In the laboratory a set of restorative mortar samples were prepared with similar chemical and mineralogical composition, porosity and visual properties (colorimetric parameters), mechanical properties and formation of contact zone between original and restorative mortar. The laboratory prepared samples were artificially aged in weathering chamber (temperature, humidity, UV/VIS radiation) simulating exposal to real environmental conditions in all four seasons. The weathering regimes were set according to temperature and humidity profiles for the relevant region. Finally, the compatibility of restoration mortar with original one was evaluated and confirmed, what enabled conservators to proceed with restorative works.

How to cite: Ranogajec, J., Vucetic, S., Frankovic, M., and Hirsenberger, H.: Characterization of historical inorganic binders and design of restorative materials - case study of the late Roman mosaic, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18128, https://doi.org/10.5194/egusphere-egu2020-18128, 2020.

In Tyrol, Austria, dolomite rock was commonly used as raw material for historic mortars and plasters. During calcination of dolomite rock, almost equal amounts of calcium oxide and magnesium oxide are produced. While the reactivity of calcium oxide is well known, the reactivity of magnesium oxide is still not completely understood. Within this study, the reactivity of magnesium oxide obtained from calcination at different temperatures (600 - 1000 °C) will be examined. For this purpose, natural magnesite (Hochfilzen, Tyrol) will be used instead of natural dolomite rock in order to minimise the influence of calcium oxide on the wet slaking curves. Both, calcination and slaking of magnesite will be studied with the help of X-ray diffraction analysis and thermogravimetric analysis. The gained knowledge is believed to be beneficial for improving the understanding of degradation processes. The study was performed within the Interreg V-A Italy-Austria project named DOLOMIA (ITAT 2036) with the funding by INTERact and the European Regional Development Fund (ERDF) being grateful acknowledged.

How to cite: Bader, T. and Diekamp, A.: Assessing the reactivity of magnesium oxide calcinated at different temperatures for understanding its role in degradation processes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19671, https://doi.org/10.5194/egusphere-egu2020-19671, 2020.

EGU2020-7843 | Displays | ERE5.1

Guessing stone behaviour before extraction

Luis Dias, Roberto Silva, Luís Lopes, António Candeias, and José Mirão

Natural Stone has always been one of the most widely used and appreciated materials in the construction of important structures, buildings and works of art. It is extremely important that the stone purchased by the consumer meets the expectations for which it was chosen, being colour one of the main aspects. Currently, there are companies with very high costs in the replacement of altered stone.

This work arises from the companies’ need to seek the extraction of stone blocks that ensure a lower susceptibility to colour change after application. To do so, a geochemical/mineralogical study was applied in a quarry located in the northern region of Lisbon, where one of the most important Portuguese lithotypes is currently explored. Featured by its excellent physico-chemical characteristics, this lithotype is further characterised by the coexistence of a blue and cream colour. The work aimed to study the presence of a mineral, pyrite, responsible for the natural discolouration of this construction resource.

The results obtained show a greater predominance of pyrite in the darker fractions of the rock, which increases while the exploration level is deeper.

How to cite: Dias, L., Silva, R., Lopes, L., Candeias, A., and Mirão, J.: Guessing stone behaviour before extraction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7843, https://doi.org/10.5194/egusphere-egu2020-7843, 2020.

EGU2020-9458 | Displays | ERE5.1

Physico-mechanical characterization of non-stabilized Compressed Earth Blocks

Marios Kyriakides, Rafail Panagiotou, Rogiros Illampas, Michalis Tapakoudis, and Ioannis Ioannou

Recent challenges faced by humanity in relation to the ongoing climatic changes around the globe, have led many practitioners and researchers search for new environmentally friendly materials to use in construction, such as earth-based materials. A specific form of an earth-based building material that nowadays receives particular attention is Compressed Earth Blocks (CEBs). CEBs comprise of soil mixed at low moisture content and are formed under high pressure in compression, without firing. The end-products can be non-stabilized, i.e., without any cement or lime added, or stabilized, whereby a small quantity of stabilizer (<12% by weight) is added, mainly for enhancing their mechanical and durability properties. CEBs, particularly the non-stabilized ones, are considered to be less expensive and environmentally friendlier, compared to the traditional fired clay bricks, due to their lower production cost and excellent recyclability potential, which significantly reduces the end-product’s environmental impact.

In Cyprus, CEBs were not used in the past, as the prevailing earth building technique on the island was adobe masonry. Recently, however, there appears to be an interest in the use of this material for contemporary construction. The work hereby presented is part of an ongoing research project that focuses on the design, production and characterization of a sustainable and eco-friendly prototype CEB masonry system that will be fabricated using raw materials originating from Cyprus. The project is funded by the European Regional Development Fund and the Republic of Cyprus, through the Cyprus Research and Innovation Foundation (Project ENTERPRISES/0618/0007).

In the framework of the aforementioned project, various types of locally sourced soils, with different mineralogical/granular composition and plasticity characteristics have been selected and used for the production of non-stabilized CEBs. A series of tests, including particle-size analysis, Atterberg limits determination, shrinkage and compaction measurements, and X-ray diffraction analyses have been carried out to determine the characteristics of the raw materials selected. In addition, compression and 3-point bending tests, capillary absorption measurements and thermal conductivity analyses have been conducted to assess the physico-mechanical properties of the CEBs produced.

XRD analyses have shown that the soils investigated are mainly composed of carbonates and silicates at different ratios. Preliminary capillary absorption tests have demonstrated that the use of a non-reactive liquid, such as acetone, is better over water in determining the sorptivity of non-stabilized CEBs. In addition, the thermal conductivity of all specimens ranged between 0.60-0.85 W/mK. Finally, the results suggest that, despite the different granular composition of the soils used, all soils demonstrated adequate mechanical properties in terms of compressive (over 5 MPa) and flexural (over 0.5 MPa) strength.  

How to cite: Kyriakides, M., Panagiotou, R., Illampas, R., Tapakoudis, M., and Ioannou, I.: Physico-mechanical characterization of non-stabilized Compressed Earth Blocks , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9458, https://doi.org/10.5194/egusphere-egu2020-9458, 2020.

EGU2020-17865 | Displays | ERE5.1

Fly ashes bulk chemistry: a new approach for XRF measurements

Renzo Tassinari, Riccardo Guida, Caterina Caviglia, Enrico Destefanis, Costanza Bonadiman, Valentina Brombin, Davide Bernasconi, and Alessandro Pavese

In this contribution we present the first results for proposing an analytical protocol to analyze fly ashes (FA) with XRF.

Fly ashes resulting from the incineration of municipal solid waste (MSW) should be considered as a hazardous material, mainly due to its potential high heavy metal content. Therefore, they have to be chemically fully characterized to facilitate primarily their safety storage and subsequently the recovery as second raw material resource. It’s worth noticing that fly ashes bulk chemistry (including volatile contents) depends on many types of variables [i.e.: geography; air pollution control devices (APCDs) and sampling sites], all related to the nature of the waste. On the basis of available data from different European waste-incineration plants, the bulk major elements contents are: Al <0.1-4.6 wt%; Ca 23.7-38.9 wt%; Fe 0.20-2.17wt%; K 0.1-2.4 wt%; Mg 0.5-1.7 wt%; Mn 0.02-0.12 wt%;  Na <0.15-2.5 wt%; P <0.02-0.92wt%; Si 0.2-8.7 wt% Cl, 7.5-28.3wt%, with volatile contents (tested by Loss of Ignition) in the range of 15-40 wt% (De Boom e Degrez, 2012; Bodénan and Deniard, 2003). 

If we consider fly ashes as “rock type” material, x-ray fluorescence (XRF) is used effectively for determining the major rock-forming elements.  However, the lack of standard calibration for this material suggested us to adopt a different strategy of calibration, using the method of Standard Addition (SA) to determine SiO2 and Al2O3 having similar mass absorption coefficients (https://physics.nist.gov/PhysRefData/XrayMassCoef/tab3.html).  

The SA method was originally designed to determine trace elements contents by addition of comparative amounts of analytes. In order to keep the characteristics of bulk chemistry invariant, in this modified calibration procedure we prepared eleven pressed powders by adding several known aliquots of SiO2 and Al2O3 (“excipients”) to the same amount of unknown FA in the constant proportion of 10% and 90%, respectively.

Plotting together the intensity values of the two analytes with the various percentages by weight of “excipients”, it was possible to generate calibration lines and acquired the percentage by weight of the two analytes in the unknown material. The Si and Al contents obtained by the calibration lines are 1.93 wt% and 1.64 wt%, respectively.

These values are different from those (2.86 wt% and 1.40 wt% for Si and Al, respectively), obtained by measurements of pure FA with routine XRF standard calibrations for silicatic rocks (Franzini et al. 1975). More measurements are needed to evaluate the accuracy of the method, however, the results presented here are promising, and hint that XRF may be used efficiently to measure FA major element chemistry, by applying the modified standard addition calibration.

References:

Bodénan, F. and Deniard P. (2003). Chemosphere, 51; 335-347

De Boom A. and Degrez  M. (2012). Waste Management, 32; 1163-1170

Franzini M., Leoni L. and Saitta M. (1975). Rend. S.I.M.P., 31: 365-378.

How to cite: Tassinari, R., Guida, R., Caviglia, C., Destefanis, E., Bonadiman, C., Brombin, V., Bernasconi, D., and Pavese, A.: Fly ashes bulk chemistry: a new approach for XRF measurements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17865, https://doi.org/10.5194/egusphere-egu2020-17865, 2020.

EGU2020-18787 | Displays | ERE5.1

Quarry waste for the production of sustainable and innovative constructional materials

Samuel Antonietti, Filippo Luca Schenker, Victor Blazquez, Vera Voney, Pietro Odaglia, Stefano Zerbi, Luigi Coppola, Chiara Bernardi, Federico Corboud, Domenico Ferrari, Christian Ambrosi, and Maurizio Pozzoni

In Canton Ticino, Switzerland, the exploitation of natural stone, mostly gneisses, is an important activity of valley’s economies but in the last decades the local quarries are facing severe economic difficulties. The current rules on the disposal of quarry wastes and the territorial planning that regulates the structure of quarries and inert landfills, is putting pressure on the economy and profitability of quarries, as the wastes represent up to 40% of the extracted material and disposal costs are huge given the important volumes. Therefore, the sustainable development of the quarry sector needs new and effective strategies, in particular in the management of quarry waste to reduce its disposal costs and possibly to re-enhance this material. Here, we propose an example of an environmentally friendly circular economy based on crushed aggregates of quarry waste for the building of high added value constructional elements.

In this applied study, we characterized the waste materials (different types of gneisses) and evaluated the crushed aggregates for their use in traditional concretes and in innovative geopolymers to use in 3D printing systems. The results showed that the concretes produced with 100% quarry waste (crushed aggregate) have good mechanical properties but moderate durability. However, it has been observed that even by simply mixing these crushed aggregates with a part of fluvial sand (allochthonous) it is possible to improve the performance of the concrete in all respects. Hence, this environmentally friendly material is suitable for many applications in the concrete industry. The aggregates were also tested for powder bed 3D printing that uses geopolymers as a binder. The first tests with this printed geopolymer suggest that this innovative constructional material may be used in non-structural architectural elements, however, further investigation is needed.

In this project it has been mapped, within the construction industry, how the economic supply chain could be configured for the reuse of this material. In particular, the usability in the production of concretes, geopolymers and mortars was highlighted, both in traditional applications and with innovative applications such as 3D printing. The analysis was carried out with particular attention to the concepts of circular economy and sustainability, identifying the main actors and their potential interests within the supply chain.

How to cite: Antonietti, S., Schenker, F. L., Blazquez, V., Voney, V., Odaglia, P., Zerbi, S., Coppola, L., Bernardi, C., Corboud, F., Ferrari, D., Ambrosi, C., and Pozzoni, M.: Quarry waste for the production of sustainable and innovative constructional materials , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18787, https://doi.org/10.5194/egusphere-egu2020-18787, 2020.

Cavitation erosion, widely existing in many flood discharge structures of concrete dams, has a direct impact on the performance of concrete. Understanding the cavitation erosion properties of concrete with different damage degrees is vital to the long-term operation safety of concrete dams. In this study, the cavitation erosion properties of concrete with different damage degrees under ultrasonic cavitation are systematically investigated in the laboratory, including three damage degrees and three ultrasonic cavitation intensities. Based on the stress-strain curve of concrete under uniaxial compression, the damage variable is defined and the corresponding concrete specimens are pre-treated. The experimental results reveal the influence of the damage degrees on the cavitation erosion properties of concrete, regarding the mass erosion characteristics, the predominant failure behaviour, and the coupling effect mechanism. Image analysis of the specimens shows some level of deterioration at the surface and inside the specimens. Under higher damage degree or cavitation intensity, the concrete is characterized by higher mass erosion rate, higher cumulative cavitation damage and worse surface smoothness. Furthermore, the micro-cracks caused by concrete damage aggravate the aggregate liberation of concrete under ultrasonic cavitation, and the crack propagation under coupling effect of damage and cavitation is most likely driven by the combination of fatigue-like crack growth and deformation, thereby reducing the service life of concrete.

How to cite: Lu, X., Chen, J., Pei, L., and Wu, Z.: Experimental Investigation on the cavitation erosion properties of concrete with different damage degrees under ultrasonic cavitation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1917, https://doi.org/10.5194/egusphere-egu2020-1917, 2020.

ERE5.2 – Heritage Stones: Global relevance vis-à-vis architectonic heritage

In cemeteries dating back to the mid-nineteenth century to the early twentieth and forming part of the cultural heritage of Brazil is a great variety of stone materials applied. Integrating cultural tourism routes, these spaces can also be used for the dissemination of geological information. To study these applications, three were chosen and the most iconic being the Campo Santo Cemetery in the city of Salvador, State of Bahia, which dates from 1844. From the state of Minas Gerais, two were chosen. The oldest belongs to the Third Order of San Francisco, from the city of São João Del Rey and was opened in the first half of the nineteenth, while the youngest, the Bom Fim located in Belo Horizonte, dates from the early twentieth century. Among the applied materials, those of national origin and others imported were identified. In the first group stand out the green schists, granites and gneisses, while in the second marbles and limestones represent the most used rocks. From the group of marble and limestone applied stand out materials of Italian and Portuguese origin, which will be considered in this work. Of the Italians, the Carrara marbles are the most frequent, while of the Portuguese predominate the Lioz type, followed by Encarnadão and, more rarely, the Sintra Blue and Negrais Yellow, all from the Lisbon-Sintra region. In the studied cemeteries, the use of marble from Carrara predominates in the tombs of the Bonfim cemetery, while Lioz marble was the most used type in the production of tomb art in the other two, which often brings records confirming its production in companies located in Lisbon or in the city of Porto. For Lioz some of its main characteristics were confirmed, such as the frequent presence of rudist fossils and their calcitic composition, typical of types historically extracted in the regions of Pero Pinheiro and Sintra. It was generally identified as a microcrystalline limestone, bioclastic, with slight chromatic variations ranging from white to beige, rosy or pink cream, with the presence of yellowish stains. Following the Lioz, another Portuguese limestone called Encarnadão appears. For this type there are chromatic variations ranging from pinkish to reddish tones, passing through shades of salmon. The Lameiras type is identified by the reddish hues. Other features found, such as the presence of stylolites, were used to identify subtypes described in the literature, such as Encarnadão Chainette present in Salvador tombs, and more rarely in São João del Rey. Other Portuguese limestones, such as Negrais yellow and Sintra blue, extracted in the Lisbon / Sintra region, were observed in ornamental applications on tombs, mainly from Campo Santo Cemetery in Salvador. While the first one is characterized by the golden yellow coloration, the second one is distinguished by the bluish-gray coloration. With very rare presence can be mentioned the use of other limestone materials, such as the Arrábida breccia, present in ornamental details.

How to cite: Costa, A.: Stone materials applied in funerary art in historical cemeteries in Brazil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2698, https://doi.org/10.5194/egusphere-egu2020-2698, 2020.

Rosso Verona marble (RV) is the commercial name for an ammonite-bearing, pink-red, nodular, limestone, occurring near the city of Verona, North Italy,  hence the name “Rosso Verona marble”.

  Geologically speaking, RV belongs to the Rosso Ammonitico Veronese (RAV) Formation, a Middle-Upper Jurassic unit within the Mesozoic successions of the Trento Plateau, within which it comprises the stratigraphic interval between the top of platform carbonates (Early Jurassic) and the base of the micritic pelagic limestones of the Maiolica Formation (Uppermost Jurassic-Lower Cretaceous; “Biancone” of older authors).

 

 The RAV Formation dominant features are the presence of hardgrounds, highlighted by Fe and Mn oxide encrustations and recording breaks in sedimentation, colour variations, and abundance of nodular facies and bioturbation. In the Verona area, the RAV is less than 30 m thick and is subdivided into three units and eight different facies (pseudonodular, mineralized, bioclastic, nodular, thin-bedded limestone, thin-bedded cherty limestone, subnodular, stromatolitic). The lowest unit is formed by pseudonodular, mineralized and massive facies; the middle unit is formed by thin bedded, cherty and subnodular limestones; the upper unit is composed of stromatolitic, pseudonodular and nodular limestones.

 

  Since Roman age, several levels of the RAV have been object of intensive excavation. Nowadays, the quarrying activity is still active in a few quarries, located in Valpolicella valley (Verona province), between the municipalities of S. Ambrogio and Monte, in the sorroundings of Mount Pastello.

 

  RV relevant versatility has made possible its application almost in any field: from rural landscape to traditional building, from sculpture to architectural works, from fine crafts objects to modern 3D realizations.

  We find it in many historical artistic and architectural buildings, such as the Ducal Palace and San Marco Basilica in Venice, many famous monuments in Verona (the “Arena”, the Pietra Bridge, the Roman Theatre),  and in all the most important churches and religious building in North Italy (Bologna cathedral; Parma Cathedral, Cremona cathedral etc.).

  Sought-after and appreciated by architects, sculptors and designers for its chromatic and textural features, RV has been and still is, one of the driving marbles of the traditional Italian dimension stone production.

 

  The note intends to provide a synthetic overview of RV marble and to propose it as a candidate to GHSR designation.

  Such a candidature is supported not only by its intrinsic geological and petrographic features, but also by several factors which are considered to fulfill the basic requisites for a GHSR designation. Among the most important, worth of mention are:

  • - its enormous impact on the history, traditions and culture of the Verona area,
  • - its almost ubiquitous use as a decorative stone (statues, columns, monuments, cosmatesque floors, inlays etc.),
  • - the importance of MARMOMACC, the yearly Verona International Fair (considered the most important worldwide Fair of the Dimension Stone sector),
  • - its current diffusion on a planetary scale,
  • - the presence of an institutional body, the Verona District, which collects an impressive number of companies whose level of expertise, experience and competence has few equal all around the world.

How to cite: Primavori, P.: Rosso Verona marble (Italy): proposed as a candidate for "Global Heritage Stone Resource", EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2873, https://doi.org/10.5194/egusphere-egu2020-2873, 2020.

EGU2020-4234 | Displays | ERE5.2

The Granite of Pena, the Building Stone of the Most Important Buildings of the Twentieth Century in Vila Real (Northern Portugal)

David Martín Freire-Lista, Luis Sousa, and Martinho Lourenço

Heritage stones have been used in different civilizations; they have a great social and economic relevance that attracts cultural tourism. In addition, they have an impact on human culture, geoheritage, geoarchaeology and architecture.

Industrialisation, the development of means of transport and new materials have led to the abandonment of historical quarries necessary for the conservation of monuments. Global Heritage Stone nomination aims at the inventorying of building stones that can be used for restoration and revitalisation of villages with quarrying tradition and focuses on the sustainable conservation of cultural heritage.

The geology of Northern Portugal is broadly composed of metamorphic rocks and granites with vestiges of historical stonework, since they have been profusely used for construction. Heritage stones have created a rich cultural heritage which has been preserved up to this date.

Documentary search, cartography and petrographic characterisation are necessary to locate the historical quarries of the stones with which monuments have been built. The use of analytical techniques, such as petrography, accelerated artificial ageing, ultrasound pulse velocity measurements and spectrophotometry will guarantee the quality, durability and colour of restoration stones.

The period of most intense development of traditional stonework in the Trás-os-Montes area occurred in the 18th century. An important historical quarry of granite with medium crystal-size was discovered in Picarreira mountain, near Pena village, in the municipality of Vila Real, Portugal (41.295378, -7.816378).

There are numerous door lintels that retain the construction date carved on them, as well as houses with carved ashlars, granite pinnacles, granaries and roadside granite crosses in Pena and its surroundings. The lintels and jambs of the doors and windows of the seminary, and the court and post office buildings, all of them in Vila Real, were built with Pena granite. The petrographic and petrophysical properties of this granite have been characterised in addition to its decay in the aforementioned buildings of Vila Real.

Given the ongoing transformation of the industry, it is important that urban planners and policy makers of cultural heritage work in tandem with contemporary needs of the cities. Furthermore, planning-led heritage conservation, careful attention and common criteria for the restoration and rehabilitation of each heritage stone are needed.

Acknowledgements: The Fundação para a Ciência e a Tecnologia (FCT) of Portugal supported the first author with the Stimulus of Scientific Employment, Individual Support 2017. CEECIND/03568/2017.

How to cite: Freire-Lista, D. M., Sousa, L., and Lourenço, M.: The Granite of Pena, the Building Stone of the Most Important Buildings of the Twentieth Century in Vila Real (Northern Portugal), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4234, https://doi.org/10.5194/egusphere-egu2020-4234, 2020.

EGU2020-4424 | Displays | ERE5.2

Global Heritage Stone Resource - Activities in Germany

Angela Ehling

The „International Union of Geological Sciences” (IUGS) enacted an initiative at the 33. World Congress in Oslo 2008 with the title “Global Heritage Stone Resource “ (GHSR). Aim of this initiative is to increase the perception and estimation of natural stones in the architectonic heritage in particular and in the geoheritage context in general. That includes to emphasize the need to protect dimension stone quarries as well as to avoid the replacements with inappropriate stones at cultural heritage sites.
Germany with its federal structures took part in this initative only since 2018. A national working group, consisting of geologists as well as representatives of the dimension stone industry and the preservation of monuments, has been founded. Besides some public information first activity was the compilation of a national list with natural stones which should be nominated for a GHSR-certification. Meanwhile members of our national group work actively with the Heritage Stone Subcommission, two stones have been nominated for certification and a book about the natural stones at UNESCO-Sites in Germany is underway and will be published within the new series “Natural Stones and World Heritage” in 2021. The activities of the German working group go ahead with the longer lasting activities of the network “stones in the city”. The aim of both is to focus on the natural stones as a natural, unique and sustainable building material, which is shaping cultural landscapes.  Even the declaration of the “stone of the year” in Germany since 10 years refers to their use as building material. Thus, all these initiatives can be combined and may focus on that stones which are worth to be a Global Heritage Stone.

How to cite: Ehling, A.: Global Heritage Stone Resource - Activities in Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4424, https://doi.org/10.5194/egusphere-egu2020-4424, 2020.

EGU2020-4792 | Displays | ERE5.2 | Highlight

For the buildings production, the better solutions against greenhouse gas emission

Marc Mequignon, Hassan Ait Haddou, and Nadege Gunia

The paper focuses on the assessment of greenhouse gas emissions produced by the walls of buildings according to their lifespan. These assessments take account the entire cycle life. The contribution of the utilization phase must be equivalent for all technical solutions for a given usage function. In the first part of the work, the methodology is described by considering a unit area of wall (i.e. 1 square metre), determining a long service life, choosing technical solutions in agreement with the specifications, establishing the lifespan of each technical solution according to experts, finding the corresponding greenhouse gas index from an appropriate database, and finally modelling the evolution of these indicators with time. Several technical solutions (concrete, brick, stone, wood, aerated concrete) are considered and lifespans range from a few years to centuries.

The results of this analysis suggest and quantify the important impact of lifespan on greenhouse gas emission indicators. Too, the stone is the best solution for a long life.

How to cite: Mequignon, M., Ait Haddou, H., and Gunia, N.: For the buildings production, the better solutions against greenhouse gas emission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4792, https://doi.org/10.5194/egusphere-egu2020-4792, 2020.

EGU2020-6084 | Displays | ERE5.2

Medieval and Early Modern alabaster exploitations in Germany: isotope fingerprints of the Forchtenberg and Witzenhausen deposits and their use in sculpture

Wolfram Kloppmann, Lise Leroux, Philippe Bromblet, Pierre-Yves Le Pogam, Catherine Guerrot, and Anne Thérèse Montech

Medieval European alabaster exploitations were relatively limited in number though not in their geographical extension. The main alabaster-exploiting regions before the 16th century were situated in the English East Midlands, in Spain (Aragon, Catalonia), France (Alpine deposits, Provence) and in Germany (Harz mountains, Franconia). From the 16th and 17th century onwards, the use of alabaster in sculpture considerably increased and new deposits were discovered and exploited. In the French Jurassic mountains, the Saint Lothain quarries gained in renown, in Tuscany, the antique quarries around Volterra reopened and East European deposits became important, from Eastern Germany, over Poland to the Western Ukraine.

We present two historical alabaster quarries in Germany, comparatively well documented from written sources: the Witzenhausen alabaster, quarried in Hesse, east of Kassel first mentioned in 1458, and the Forchtenberg mine, in Württemberg, 70 km SW of Würzburg, exploited in the late 16th to 17th century by several generations of the same family of sculptors, the Kern dynasty.

We were able to localize the Witzenhausen deposits around the nearby village of Hundelshausen where Permian (“Zechstein”) evaporites outcrop and are still quarried for plaster production. Most of the encountered varieties are light to dark grey, strongly folded, with brecciated layers. The earliest surviving documented artwork made from this material dates back to 1516, the funeral monument of William II, Landgrave of Hesse (1469-1509), in the church St. Elisabeth, Marburg, Hesse, by the sculptor Ludwig Juppe. The Sr, S and O isotope signatures of the Hundelshausen quarries and the funeral monument are identical and fall in the typical range of Permian alabaster, which, together with the characteristic texture should enable us to identify this type of stone in artworks with unknown provenance.

The Forchtenberg alabaster was quarried from the mid-16th century onwards in galleries and was the privileged material of the Kern family whose house had a direct entry to the alabaster mine. Prominent members of this family are Michael Kern III (1580-1649), who worked for the counts of Hohenlohe and produced many monumental sculptural ensembles in alabaster and his younger brother Leonhard Kern, working in alabaster, ivory and wood, considered as one of the major sculptors of the German Baroque. The Forchtenberg alabaster of Triassic (Muschelkalk) age shows a very characteristic banking and its isotope fingerprints distinguish it from all other Triassic (Keuper) deposits so far investigated in S Germany, notably by a distinct enrichment in 34S.

 

How to cite: Kloppmann, W., Leroux, L., Bromblet, P., Le Pogam, P.-Y., Guerrot, C., and Montech, A. T.: Medieval and Early Modern alabaster exploitations in Germany: isotope fingerprints of the Forchtenberg and Witzenhausen deposits and their use in sculpture, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6084, https://doi.org/10.5194/egusphere-egu2020-6084, 2020.

EGU2020-10703 | Displays | ERE5.2

Italian travertine in building heritage

Rossana Bellopede and Paola Marini

Travertine is one of the most common stone for building construction used in many countries starting from ancient times. It was one of the favorite stones of the Roman empire: the main example is  the Colosseum in Rome. All over the world travertine is found in important monuments and in various modern structures: for example, the Conservation Center of the J. Paul Getty museum in Los Angeles and Jiangsu Provincial Art Museum in Nanjing, China and it is very appreciated and requested in the construction of recent thermal bath. In addition to Italian travertine, the other famous types of this stone are known throughout Europe (i.e. Germany, Hungary) and Asia (i.e. Turkey, China, Iran).

Travertine is considered a durable stone despite the weathering caused by air pollution. It is observed in urban areas that the facades may be covered with a black crust where gypsum and calcite are the main minerals .

Nine different types of travertine coming from Tuscany and Umbria (Italy) have been investigated. Petrographic analysis, physical mechanical and artificial ageing test have been performed.

Among the different kind of travertine different texture can be identified as: not laminated, laminated: laminated with sub parallel sheets, laminated with concentric sheets. The various travertine depositional structures have been in compared to the different answer to artificial ageing. Finally, it can be asserted that the durability is not connected only with porosity and the analysis of the complex texture of this kind of stone cannot give a simple solution related to its durability.

 

How to cite: Bellopede, R. and Marini, P.: Italian travertine in building heritage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10703, https://doi.org/10.5194/egusphere-egu2020-10703, 2020.

EGU2020-11608 | Displays | ERE5.2

Uses of Building Stones in Architectural Elements of El Kantara Town, Biskra (Algeria).

Wahiba Moussi, Khaled Selatnia, David Martín Freire-Lista, and Luis Sousa

 

Abstract- The preservation and conservation of historical and cultural built heritage is necessary to preserve the history of cities and the identity of populations. Built heritage is a cultural asset whose preservation and protection is essential to any society. Building stones are one of the most widely used construction materials throughout history. Normally, building stones come from the vicinity of where they are used, which ensures the integration of the built heritage with its surroundings. Due to their decay, building stones need to be preserved and conserved.

El Kantara, formerly Calceus Herculis, is an oasis located 52 kilometers north of Biskra, Algeria. It is characterized by its rich history with alternation of different civilizations: Roman, Muslim and French. El Kantara is an example of vernacular architecture that uses building materials provided by the local environment. Due to the mountainous nature of El Kantara, building stones have been one of the most used materials since the Roman period.

Our research is based on Dachra Dhahraouia as a case study. It is one of three villages in El Kantara and the oldest core of the city. It was founded around the 7th century by a group of families who had arrived to this place during the Muslim conquests because of its strategic location and its position, on the heights overlooking the El Haï valley and the palm grove. When the French settled in El Kantara and created their village, the name Dachra Dhahraouia changed to Red Village because of its red earth color.

Dachra Dhahraouia is a protected area (May 6, 2013). It is considered a model of authentic Arab-Berber architecture, for its type of construction, its doors, its alleys, the organization of its houses, its traditional materials and its architectural character in harmony with nature, traditions and customs. The building stones are used in houses, in foundations of historic walls, in entrance steps in public spaces as benches and in steps of stairs. They are also used in the fence wall of the old cemetery.

The aim of this paper is to study the different existing building stones used in architectural elements of Dachra Dhahraouia. In order to achieve the purpose of this study, six samples (5 × 5 × 5 cm) of the different stone types were tested from different houses and public spaces. Polarization optical microscopy and X-ray diffraction techniques were used for petrographic characterization. Bulk density, porosity, color and ultrasound propagation wave measurements were used for petrophysic characterization of the heritage stones.

 

The most-used building stone found in Dachra Dhahraouia is a limestone, used in foundations, fence walls and in steps of stairs. Quartzite valley pebbles are used just in the foundations. Dolomite is also part of the building stones used in public spaces as pavements. Also, ashlars from the Roman period are reused in entrance steps and in the foundations of some houses.

 

Index Terms- building stones. architectural elements. El Kantara. Heritage.

How to cite: Moussi, W., Selatnia, K., Freire-Lista, D. M., and Sousa, L.: Uses of Building Stones in Architectural Elements of El Kantara Town, Biskra (Algeria)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11608, https://doi.org/10.5194/egusphere-egu2020-11608, 2020.

Taj Mahal, the iconic mausoleum, known for finest quality white Makrana Marble from Rajasthan, is inlaid with numerous natural stones which add to the beauty of this architectural wonder from India. Makrana marble has been recently designated as a Global Heritage Stone Resource (GHSR) by IUGS. Makrana marble is the first GHSR from India and in fact the first from the whole of Asia to join the list of 22 designated GHSR’s from around the globe.

The Taj mausoleum is part of the Taj Mahal complex which has numerous edifices built in marble and red sandstone. The white Makrana Marble mausoleum is placed in the center of the northern periphery of the Complex. The main mausoleum is a magnificent octagonal edifice with its arched doorways, walls, floor adorned with intricate inlaid work in semi-precious natural stones and rocks that add an aesthetic dimension to this otherwise white marble edifice. The natural stones adorning the various components of the marble edifice include Yellow Jaisalmer Limestone, black slate, carnelian, agate, Khatu Rainbow Sandstone, onyx, lapis lazuli, malachite, jade, mother pearl, etc. The inlaid natural stones of Taj Mausoleum were procured from far off places during the Mughal rule in India.

How to cite: Kaur, G.: Inlaid natural stones in Makrana Marble Taj Mausoleum of India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12693, https://doi.org/10.5194/egusphere-egu2020-12693, 2020.

Labradorite is an unusual gemstone in many respects, despite being a variety of plagioclase feldspar, probably the most common mineral in the Earth’s crust. Calcic plagioclase is common in mafic igneous rocks, especially gabbros, norites, troctolites and anorthosites, but it is generally unremarkable in appearance. However, gem labradorite exhibits striking colours on cleavage surfaces when viewed from exactly the right direction. Intense blues and greens are most common, but shades of brown, yellow and red also occur. This phenomenon results from optical interference effects caused by microscopic exsolution lamellae that have very specific and consistent thicknesses. This special type of iridescence is termed ‘labradorescence’ because it is very specific to this mineral. Labradorite was one of the earliest gemstones to be recognized in Canada, first collected by a Moravian missionary around 1773, and named by the famous mineralogist Abraham Werner in 1780. However, it was noted long before this, as there is an Inuit legend about the Northern Lights becoming imprisoned on the rocky coast of Labrador. The typical blue and green colours of the stone are indeed reminiscent of the auroral displays for which the region is famous.

 

            In its type area around the town of Nain, labradorite is hosted by massive anorthositic rocks that are regionally extensive. The anorthosites generally contain > 90% plagioclase, with lesser pyroxene, olivine and Fe-Ti oxides. Labradorescence is variably present in the feldspars, and small pockets of bright colour occur sporadically within otherwise unremarkable rocks at many locations. More extensive gem-quality labradorite is associated with very coarse-grained (pegmatitic) zones, and several attempts at exploiting such material were made at a location now known as Tabor Island. Another well-known location in an inland area is appropriately known as “the Pearly Gates”, but this remains unexploited.  Coarse- grained, equigranular anorthosite containing 5-20% iridescent feldspar was quarried for dimension stone near Nain intermittently for about 20 years, and was marketed under the trade name ‘Blue Eyes’. Much potential remains for future production of stone of this general type in the Nain area, although the remote location and climate present logistical challenges.

 

                Labradorite also occurs in many other places, and sources of significance include Norway, Finland, Australia and the island of Madagascar. Scandinavia is famous for the dimension stone known as Larvikite or “Blue Pearl”. This is a feldspar-rich monzonite that contains much iridescent plagioclase, but is darker in colour than typical Labrador anorthosites. Madagascar provides much of the material now used for craft purposes, even in the northern region where the mineral was first recognized. However, labradorite-rich stones are now being used by Inuit carvers, in addition to more traditional materials such as soapstone and serpentinite.

How to cite: Kerr, A.: Labradorite gemstones and related ornamental stones from the type area on the coast of Nunatsiavut (Labrador), Canada, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13222, https://doi.org/10.5194/egusphere-egu2020-13222, 2020.

EGU2020-17808 | Displays | ERE5.2

Geo-referenced database of Ornamental and Building Stones from Piemonte region: from Heritage Stone exploitation to potential economical and social impacts.

Francesca Gambino, Giovanna Antonella Dino, Alessandro Borghi, Anna d'Atri, Luca Barale, Sergio Enrico Favero Longo, Marco Giardino, Luca Martire, Luigi Perotti, and Fabrizio Piana

Piemonte region (Northern Italy) shows an extraordinary richness of ornamental stones, whose exploitation strongly influenced the local culture during the centuries. Indeed, more than 100 lithotypes, mainly exploited in valleys and mountain areas, are used in the local, urban and architecture heritage of the region.

The starting point of the present work consists in the creation and implementation of a dynamic geodatabase of the ornamental and dimension stones of Piemonte region. The geodatabase relies on the data model of the GeoPiemonte Map, derived from a thorough revision of existing geological maps and papers and presently available on a WebGIS application as an interactive scalable map on ARPA Piemonte geoportal.

The second step of the work consists in the dissemination and exploitation of results for enhancing the use of local stones for restoration of historical buildings, infrastructures (eg. stone bridges) and rural villages, and for the construction of new “sustainable” buildings and houses (energy saving, use of natural materials, reduction of greenhouse gas emissions due to transports, etc.).

The structure of the DB and the information reported in it are easily accessible and can be elaborated, implemented and shared not only by researchers, but also by public authorities, trade associations, consultants, etc., in order to (potentially):

  • better program quarrying activities and enhance the exploitation at local level, trying to boost the use of local stones for restoration of historical buildings, rural villages and infrastructures;
  • strongly promote the knowledge of the cultural and historical heritage at local level (not only historical villages, but also historical quarries, quarrymen villages, areas characterized by the presence of working plants, etc.);
  • collect information for all the stone materials and cultural heritage present in Piemonte region.

The structure of the DB and the methodology to collect data to improve it are replicable and applicable to other regions (at national and international level). The use of the DB may have economic and social returns, due to the reinvigoration of the ornamental and dimension stones market and to the potential growth of the quarrying activities (implementation of the staff in charge) and of their spin offs (working plants, restoration experts, designers, building enterprises, etc.).

Many of the stones reported in the DB could be considered as Heritage Stones, being some of them already presented in previous congresses and papers (Montorfano and Baveno granites, serizzi and beole gneisses, Candoglia marble, Luserna stone gneiss, Bargiolina quartzite, etc.).

This work was carried out in the framework of the GeoDIVE research project concerning the geodiversity of the Piemonte region, “from rocks to stones, from landforms to landscapes”, funded by Compagnia di San Paolo and University of Torino.

 

How to cite: Gambino, F., Dino, G. A., Borghi, A., d'Atri, A., Barale, L., Favero Longo, S. E., Giardino, M., Martire, L., Perotti, L., and Piana, F.: Geo-referenced database of Ornamental and Building Stones from Piemonte region: from Heritage Stone exploitation to potential economical and social impacts., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17808, https://doi.org/10.5194/egusphere-egu2020-17808, 2020.

This study shows results of geochemical pXRF-data of a closed data set from selected calcareous and mixed calcareous-siliciclastic lithotypes of ornamental and building stones, mainly attributed to corallinacean Leitha Limestone, its succeeding reworked and variegated deposits known as Detrital Leitha Limestone, as well as to younger or lateral interconnected oolites, coquinas and low calcitic sandstones. They altogether represent shallow marine deposits in the Central Paratethys Sea in the Middle to Upper Miocene (16–5 my). Certain analytical reasons require comparing quantities in the geochemical compositions just within the presented dataset.

The stones in focus were prominent building and ornamental stones in former centuries and embody the stonemason culture during various historic periods e.g. in Vienna (St. Stephen’s Cathedral, Vienna State Opera). A still active quarry at Sankt Margarethen im Burgenland provides replacement material. The heritage value of these appreciated freestones is emphasised by their use for various cultural monuments and for buildings and infrastructure already when this region was part of Imperium Romanum. The interdisciplinary archaeological-geological project CarVin (Stone Monuments and Stone Quarrying in the Carnuntum - Vindobona Area, G. Kremer) provided the opportunity to relate archaeological stone objects with native quarries from the nearest possible locations by using this non-destructive analysing technique. The aim was to compare fine-grained archaeological stone objects with samples of similar lithologies from investigated outcrops for potential likenesses. In the present dataset we include 300 archaeological objects and 155 geological samples, each measured at least twice. We used the NITON XL3t 900s GOLDD Air of AnalytiCON Instruments. Its Mining Mode was used to measure main, minor and trace elements with an atomic mass from Magnesium upwards. The internal software converts the composition into percentage. Therefore compositional data analysis recommends a statistical centered log-ratio transformation. Scatterplots with certain elements by pairs show significant distributions. A preceding hypothetical grouping of the measured geological samples draws upon their lithology and their affinity to specifically defined quarry regions (see https://meetingorganizer.copernicus.org/EGU2018/EGU2018-18923.pdf). The grouping of the geological samples shows a good expression in the Ca-Sr plot and Sr-Ti allows a good differentiation as well. However, the attempt to differentiate between two specific areas – Leitha Mountains northeast and southwest – seems improbable. The expressed situation concerning the majority of the archaeological objects shows some similarities but also conspicuous differences: a clear depletion in Ba, Ca and Mg and partly in Mn and Sr linked with a striking enrichment in sulphur. Without further analysing methods we make environmental effects liable for that.

Although more measurements per sample and object would have improved the study, the results from the pXRF method are supportive for petrological examinations. Nonetheless, a very sensitive handling and chemical data evaluation is critical with this method (analysing influences, surface conditions).

How to cite: Moshammer, B.: Application of a handheld X-ray fluorescence analyser to trace the provenance of Roman monuments of Neogene lithotypes to quarries in the Leitha Mountains, Hainburg Mountains and along the south-west border of the Vienna Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18871, https://doi.org/10.5194/egusphere-egu2020-18871, 2020.

EGU2020-19104 | Displays | ERE5.2

Vicoforte sandstone in Cultural Heritage

Paola Marini and Rossana Bellopede

The large family of sandstone covers stones with different grains, porosity, cement or matrix, compactness, chemical composition etc. and it is widely used as cladding stone, even in historic buildings. From literature, its decay is usually connected to the action of salts or to black crusts because of pollution.

Being sandstone a sedimentary rock deposited in layers, often the quarry produce material with a high variability in aspects and mechanical properties. This can be also evident in the resistance to decay shown in the monuments that is typical of each facies though it has been exposed for the same lapse of time and under similar climatic conditions. This is the case of Arenaria di Vicoforte used on the facade of the Vicoforte Sanctuary (Vicoforte - Mondovì) and probably on the external pilaster of the Monte dei Cappuccini church in Turin. Both the catholic monuments were designed by architect Ascanio Vitozzi at the end of the XVI century . It is possible to compare the high degree of weathering of the pilasters  of the Monte dei Cappuccini church with the good ageing behaviour shown by the Vicoforte Sanctuary sandstone.

Different durability tests were carried out: resistance to salt crystallisation, resistance to ageing due to SO2 action in the presence of humidity, frost resistance. The mass weight difference, method used to evaluate the forecast of decay in various european standardardized methodologies, does not always offer a satisfactory estimation of the decay of stone after salt crystallization while water absorption, which is well correlated to the physical mechanical characteristics of the stone, together with a visual inspection, is a good index of the decay in order to obtain a distinction, in terms of durability, between different sandstones even of a same geological district.

A visit to the quarry solved any doubts: two different facies of the Vicoforte sandstone were quarried, one yellowish and the other grey. The first, mainly silicatic, was used for the Sanctuary near the quarry, the grey one (with a carbonate content of 18%) could be the one sent to Turin.

The variability of the rock characteristics in the quarry should therefore be taken into account when evaluating the durability of the sandstone.

How to cite: Marini, P. and Bellopede, R.: Vicoforte sandstone in Cultural Heritage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19104, https://doi.org/10.5194/egusphere-egu2020-19104, 2020.

EGU2020-22186 | Displays | ERE5.2

Geoarchaeological non-invasive techniques (pMS, pXRF, Schmidt Hammer) to study quarrying activity of the Corsican granites and the related monuments during the Roman period

Nadine Mattielli, Antoine Triantafyllou, Sébastien Clerbois, Gaël Brkojewitsch, Letizia Nonne, Nicolas Paridaens, and Nicolas Authom

Although several authors have previously reported the limited Roman quarrying activity in Corsica, recent research programs revealed a real basin of granitoid quarries in the archipelago of Lavezzi (Strait of Bonifacio, southern Corsica). A series of fundamental archaeological questions have arisen for which a geological expertise could provide new answers: (i) what was the quarrying strategy during Roman times in the Strait of Bonifacio area, (ii) is it possible to characterize and catalogue the quarried granitic rock materials and establish ‘quarry-to-monument’ relationships (i.e. comparisons with building stones and quarries), and (iii) how to identify and constrain the timing of major phases of quarrying activity (discrimination of Roman activities relative to modern footprints in the quarries)?

To achieve these goals, our geoarchaeological study proposes a pluri-disciplinary, innovative, non-destructive methodological strategy, coupling techniques of digital photogrammetry, field petrography, mineralogical and chemical analyses by portable magnetic susceptibilimeter (pMS) and portable X-Ray Fluorescence spectrometer (pXRF) respectively, and physical rock properties using a Schmidt Hammer. The field geochemical measurements were calibrated by laboratory major and trace element analyses on ICP-OES and HR-ICP-MS, respectively. Here, we present preliminary results of two field campaigns. These results indicate that a statistically significant number of measurements by pMS and pXRF from the same representative area of the studied rocks – natural rocks or building stones, can be used to discriminate different quarried sites and identifying distinct rock sources. Several profiles of rebound measurements at the rock surface using the Schmidt Hammer (indicative of the degree to which a rock surface has been weathered and by extension, exposed) might help revealing the initial volume of natural rock massifs before their initial extraction. Our study provides original and reproducible techniques contributing to significantly improve geoarchaeometric investigations and brings key information on the quarrying activity in southern Corsica during Roman times along with its implications on the Mediterranean commercial exchange trades.

How to cite: Mattielli, N., Triantafyllou, A., Clerbois, S., Brkojewitsch, G., Nonne, L., Paridaens, N., and Authom, N.: Geoarchaeological non-invasive techniques (pMS, pXRF, Schmidt Hammer) to study quarrying activity of the Corsican granites and the related monuments during the Roman period, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22186, https://doi.org/10.5194/egusphere-egu2020-22186, 2020.

EGU2020-22413 | Displays | ERE5.2

Heritage Building Stones from Évora, Portugal

Luis Lopes

The city of Évora, a World Heritage Site recognized by UNESCO in 1986, also owes this recognition to the stones that built its monuments and preserve them until today.

This work brings together the contributions that we have gathered over the past three decades and allow us to have a very complete idea, not only about the materials used in the hundreds of monuments and historic buildings but also about their provenance. If some materials are so emblematic that they allow an immediate identification with the naked eye, others needed more sophisticated and precise techniques so that there was no doubt about their origin.

The igneous rocks and gneisses of granite composition are part of the “Massif of Évora” on which the city is built. Thus, and quite naturally they are by far the most represented group in monuments from all historical periods. Its function is essentially structural, but there are also functional, ornamental and decorative objects. For example, the oldest megalithic structures found in the vicinity of the city are made up of large granite blocks that often had to be transported to their locations.

On the other hand, many gargoyles and statues that decorate the churches are also made up of these granite rocks. On these, the natural erosion of centuries of exposure to the environment has led to a state of alteration, sometimes very accentuated, which would justify its replacement by replicas sculpted in similar rocks. Provenance studies have made it possible to identify old quarries in the vicinity of the city where, on the one hand, the ancient rock extraction techniques can be observed and on the other hand, they allow the obtaining of the raw material necessary for these restoration and conservation works. In any case, they are places that need to be inventoried and protected, with the municipality already aware of their existence.

As well as the monuments of the Roman Period, also the structures of the Medieval Period, such as the city walls, the Cathedral (started to be built in 1186 AD) and all the great churches, were also built with these granitoids.

In addition to these rocks, many others of multiple varieties and origins are present. The marbles, especially the Estremoz Marbles (Global Heritage Stone Resource), are ubiquitous in the city, but there are also emblematic marbles from other places, some easily identifiable (ie Viana do Alentejo, Escoural, Trigaches, Serpa and Vila Verde de Ficalho, for presenting mineralogy, textures, colors and patterns which, together with more recent analytical techniques, have confirmed its provenance.

Sedimentary rocks, with emphasis on Portuguese Mesozoic limestones, ie Lioz - GHSR and Brecha da Arrábida - GHSR candidate, among others more rare and with very specific use in ornamental details, are also present and contribute to enrich a heritage in stone that makes this city so special and very popular with tourists of all nationalities.

Acknowledgments: the authors thank to FCT for funding the ICT (UID/GEO/04683/2019), as well as COMPETE POCI-01-0145-FEDER-007690.

How to cite: Lopes, L.: Heritage Building Stones from Évora, Portugal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22413, https://doi.org/10.5194/egusphere-egu2020-22413, 2020.

ERE5.4 – State-of-the-art in mineral exploration

This study was made with complex geophysical and geological observations by the DSS-MRW seismic reflection and refraction profiles, which cross Uzbekistan. The aim of our study was to reveal new features, which are characteristic of the upper mantle rocks, related to morphology of bodies, their physical properties, consisting mainly in their contrasting values for contiguous blocks, and general increased velocity and density of the rocks they contain.  The methodology of establishment of integrated dynamic interactive models on ore-magmatic concentres consists of two consecutive stages including: 1) the methodology of integrated geological-geophysical processing and interpretation of potential fields and seismic profiles cross cutting ore-magmatic concentres; 2) the methodology of creation of a united interactive 3-D model in ArcGIS in combination with materials of remote sensing. Each of these stages is divided into more detailed sub-stages. During the study of the deep structure of ore-magmatic concentres, the first step is the integrated methodology of the processing and interpretation of potential fields. It is mainly orientated at the identification of positions of geometric borders of the division of mediums determined by the data of seismic exploration of preferably deep seismic sounding. Our experiences shows  that the use of these potential fields for the area zoning of the territory, identification of the depth of manifestation of isolated blocks and their density may significantly affect the interpretation of seismic exploration data. Therefore, the implementation of the method-based interpretation of data of gravitational and magnetic fields preceding, the stage of the construction of the integrated model enables a more complete use of opportunities of these methods. Anomalous objects are isolated in the Earth crust on the basis of the interpretation of potential fields using the methods of the solution of direct and inverse tasks. An integrated interpretation of potential fields enablers the maximal use of information available in this field for the analysis of the deep structure. The processing of data is an important integrated part of the whole process of development of the 3-D model of the ore-magmatic concentre within the frames of the GIS project. New regional features have been revealed: they include peculiarities of the Earth's crust's deep geological structure and spatial distribution of deposits; they are contact areas of the Earth's crust geoblocks with anomalously high and low seismic and density parameters. Mapping of these zones helps select new ways in the search for mineral deposits.

 

How to cite: Sidorova, I.: Integrated dynamic interactive models of ore-magmatic concentres in Uzbekistan , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-617, https://doi.org/10.5194/egusphere-egu2020-617, 2020.

EGU2020-2078 | Displays | ERE5.4

The Mineral Exploration of the Haimur Gold-Mine in the South Eastern Desert-Egypt, by Using Geophysical Techniques

Mahmoud Mekkawi, Ayman Ismail, Mohamed Al Deep, Sultan Arafa, Mahmoud Abdel Hai, and Abbas Mohamed

The Haimur gold mine is located in the south Eastern Desert, Egypt, about 200 km far from Aswan city and is known as historical mine dated back to (7th–11th centuries). An evidence of ancient mining activities is manifested by excavated quartz veins and old stone tools used for gold extraction. A number of important ancient gold mines in the Allaqi area have, however, received relatively little geological and geophysical attention. Haimur area comprises a variety of Precambrian rocks including igneous and metamorphic units. It is covered by: ophiolite assemblage, metasediments and metavolcanic.

The geophysical measurements are carried out along the ancient mine where the quartz veins are concentered. Several geoelectrical and land magnetic profiles were done perpendicular to the structure of the area, The Electrical Resistivity was acquired by using dipole-dipole configuration of electrode spacing 5, 10 and 15 m of lengths ranging from 160-240 m. In additional to magnetic profiles are applied around old mine. The results indicate that the quartz veins are accomplished with sulfide zones which refer to low resistive zones, high chargeability with moderate to high magnetic anomalies.

Key words: South Eastern Desert, Alter mineralized zone, Land magnetic, Electrical Resistivity and Induced polarization.

How to cite: Mekkawi, M., Ismail, A., Al Deep, M., Arafa, S., Abdel Hai, M., and Mohamed, A.: The Mineral Exploration of the Haimur Gold-Mine in the South Eastern Desert-Egypt, by Using Geophysical Techniques, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2078, https://doi.org/10.5194/egusphere-egu2020-2078, 2020.

EGU2020-8035 | Displays | ERE5.4

Hyperspectral drill-core imaging for ore characterization

Laura Tusa, Mahdi Khodadadzadeh, Margret Fuchs, Richard Gloaguen, and Jens Gutzmer

Mineral exploration campaigns represent an essential step in the discovery and evaluation of ore deposits required to fulfil the global demand for raw materials. Thousands of meters of drill-cores are extracted in order to characterize a specific exploration target. Hyperspectral imaging is recently being explored in the mining industry as a tool to complement traditional logging techniques and to provide a rapid and non-invasive analytical method for mineralogical characterization. The method relies on the fact that minerals have different spectral responses in specific portions of the electromagnetic spectrum. Sensors covering the visible to near-infrared (VNIR) and short-wave infrared (SWIR) are commonly used to identify and estimate the relative abundance of minerals such as phyllosilicates, amphiboles, carbonates, iron oxides and hydroxides as well as sulphates (Clark, 1999). The distribution of these mineral phases can frequently be used as a proxy for the distribution of ore minerals such as sulphides. Typical core imaging systems can acquire hyperspectral data from a whole drill-core tray in a matter of seconds. Available sensors record data in several hundreds of contiguous spectral bands at spatial resolutions around 1 mm/pixel.

​​In this work, we apply a local high-resolution mineralogical analysis, such as SEM-MLA (Kern et al., 2018), for a precise and exhaustive mineral mapping of some selected small samples. We then upscale these mineralogical data acquired from thin sections to drill-core scale by integrating hyperspectral imaging and machine learning techniques. Our proposed method is composed of two main steps. In the first step, after initially co-registering the hyperspectral and high-resolution mineralogical data and making a training set, a machine learning model is trained. In the second step, we apply the learned model to obtain mineral abundance and association maps over entire drill-cores.

​​The mapping is further used for the calculation of other mineralogical parameters essential to exploration and further mining stages such as modal mineralogy, mineral association, alteration indices, metal grade estimates and hardness. The proposed methodological framework is illustrated on samples collected from a porphyry type deposit, but the procedure is easily adaptable to other ore types. Therefore, this approach can be integrated in the standard core-logging routine, complementing the on-site geologists and can serve as background for the geometallurgical analysis of numerous ore types.  

​​

​​Clark, R. N., 1999, “Spectroscopy of rocks and minerals, and principles of spectroscopy,” in Remote sensing for the earth sciences: Manual of remote sensing, vol. 3, John Wiley & Sons, Inc, pp. 3–58.

​​Gandhi, S. M. and Sarkar, B. C., 2016, “Drilling,” in Essentials of Mineral Exploration and Evaluation, pp. 199–234.

​​Kern, M., Möckel, R., Krause, J., Teichmann, J., Gutzmer, J., 2018. Calculating the deportment of a fine-grained and compositionally complex Sn skarn with a modified approach for automated mineralogy. Miner. Eng. 116, 213–225.

How to cite: Tusa, L., Khodadadzadeh, M., Fuchs, M., Gloaguen, R., and Gutzmer, J.: Hyperspectral drill-core imaging for ore characterization, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8035, https://doi.org/10.5194/egusphere-egu2020-8035, 2020.

The Cloncurry region lies in NW of Queensland and includes the Mount Isa Inlier, one of the most highly endowed metallogenic provinces in Australia, which has a long history of mining and exploration. The area is covered by the Jurassic-Cretaceous Carpentaria and Eromanga Basin sediments with the Mount Isa Inlier outcropping to the West and South. The fully concealed Millungera Basin underlies younger basins to the East. In order to de-risk further mineral exploration in this region it is important to know the thickness of cover. There are a variety of geophysical data available that can be used to estimate cover thickness. The point depth estimates of cover are derived from geophysical data using different inference methods. In order to create a map, these individual depth estimates must be reconciled/interpolated. The conventional interpolation methods do not produce the most optimal solution since these methods don’t easily account for discrepancies in the geophysical data distribution, resolution of the data and consequently variable accuracy of the cover thickness depth estimates. Also, most of these techniques do not produce an uncertainty estimate of the result. We have developed a Bayesian estimate fusion method that accounts for the variable data inaccuracies of the point cover thickness estimates which produces a map of cover thickness and its uncertainty. Additionally, the method uses non-intersecting drill holes, which were not usually utilised to create a map of the cover thickness. The method deals with outliers, by differentiating between the point depth estimates related to the cover-basement interface and the false positives that might be coming from the intrasedimentary units or the deeper basement. Lastly, the method incorporates existing fault information which allows to better capture sharp cover thickness changes.

How to cite: Markov, J. and Visser, G.: Reconciling Cover Thickness Estimates in Cloncurry Region in Queensland, Australia using Bayesian Estimate Fusion, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12172, https://doi.org/10.5194/egusphere-egu2020-12172, 2020.

EGU2020-13586 | Displays | ERE5.4

Making exploration of underground flooded mines a reality - the UNEXUP solution

Márcio Pinto, Norbert Zajzon, Luís Lopes, Balazs Bodo, Stephen Henley, José Almeida, Jussi Aaltonen, Claudio Rossi, and Gorazd Zibret

The UNEXUP project, funded under EIT Raw Materials, is a direct continuation of the Horizon 2020 UNEXMIN project. While in UNEXMIN efforts were made towards the design, development and testing of an innovative exploration technology for underground flooded mines, in UNEXUP the main goal is to push the UNEXMIN technology into the market, while further improving the system’s hardware, software and capabilities. In parallel, the aim is to make a strong business case for the improved UNEXUP technology, as a result of tests and data collection from previous testing. Improvements to the UX-1 research prototypes will raise technology readiness levels from TRL 6, as verified at the end of the UNEXMIN project, to TRL 7/8 by 2022. A "real service-to-real client" approach will be demonstrated, supporting mineral exploration and mine surveying efforts in Europe with unique data from flooded environments that cannot be obtained without high costs, or risks to human lives, in any other ways.

The specific purpose of UNEXUP is to commercially deploy a new raw materials exploration / mine mapping service based on a new class of mine explorer robots, for non-invasive resurveying of flooded mines. The inaccessibility of the environment makes autonomy a critical and primary objective of the project, which will present a substantial effort in resurveying mineral deposits in Europe where the major challenges are the geological uncertainty, and technological / economic feasibility of mine development. The robot’s ability to gather high-quality and high-resolution information from currently inaccessible mine sites will increase the knowledge of mineral deposits in Europe, whilst decreasing exploration costs – such as the number of deep exploration drillholes needed. This can potentially become a game changing technology in the mining panorama, where the struggle for resources is ever increasing.

On the technical side, a fourth robot, modular in nature, will be added to the current multi-robot platform, providing additional functionalities to the exploration system, including better range and depth performance. Hardware and software upgrades, as well as new capabilities delivered by the platform will greatly extend the usefulness of the platform in different environments and applications. Among these: rock sampling, better data acquisition and management, further downsizing, extended range, improved self-awareness and decision making, mature post-processing (such as the deployment of 3D virtual reality models), ability to rescue other robots, and interaction with the data will be targeted during the next years. Upgrading the overall technology with these tools, and possibly additional ones, will allow the system to operate with more reliability and security, with reduced costs.

These added functions arise from different stakeholders’ feedbacks from the UNEXMIN project. UNEXUP targets parties from the mining, robotics and mineral exploration sectors, as well as all other sectors that have any kind of underwater structure that needs to be surveyed – caves, underground reservoirs, water pipelines and fisheries are among them. For the purpose of exploitation of the technology, a joint company was founded, “UNEXMIN GeoRobotics Ltd”, which is part of the UNEXUP consortium, and is responsible for selling the service to the market.

How to cite: Pinto, M., Zajzon, N., Lopes, L., Bodo, B., Henley, S., Almeida, J., Aaltonen, J., Rossi, C., and Zibret, G.: Making exploration of underground flooded mines a reality - the UNEXUP solution, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13586, https://doi.org/10.5194/egusphere-egu2020-13586, 2020.

EGU2020-19269 | Displays | ERE5.4

Regional scale prospectivity modelling of NW India for REE deposits associated with carbonatites and alkaline complexes

Malcolm Aranha, Alok Porwal, Manikandan Sundaralingam, Amber Markan, Ignacio González-Álvarez, and Karunakar Rao

The rare earth elements (REEs) are a group of seventeen metals including 15 lanthanides, scandium and yttrium.  These metals have been projected to be critical for future industrial development. However, India currently does not have any economic grade primary deposit of REEs; all of India’s production comes from monazite-bearing beach sands along the eastern and western coasts that have been derived from REEs-enriched continental rocks such as pegmatites or carbonatites. This contribution documents a GIS-based prospectivity model for exploration targeting of REE associated with carbonatites and alkaline-complexes in the geologically permissive tracts of NW India comprising parts of western Rajasthan and northern Gujarat. A mineral systems approach is applied to model the key ingredients of an REE system including geodynamic setting; fertile mantle/crustal sources of REEs; deep to shallow crustal architecture; and REE deposition.  This conceptual genetic model of REE mineral systems is, in turn, used to identify the key regional-scale REE-deposit targeting criteria in NW India. Regional-scale multi-parametric exploration datasets are processed to represent the targeting criteria in form of predictor GIS layers. Finally, an expert-driven fuzzy inference system is designed for delineating and raking prospective REE targets. Simultaneously, the stochastic and systemic uncertainties in the prospectivity modeling are modelled to delineated (a) high priority REE exploration targets areas with low uncertainty and high prospectivity for immediate ground follow up and (b) areas with high uncertainty and high prospectivity for further data acquisition in order to reduce uncertainty.

How to cite: Aranha, M., Porwal, A., Sundaralingam, M., Markan, A., González-Álvarez, I., and Rao, K.: Regional scale prospectivity modelling of NW India for REE deposits associated with carbonatites and alkaline complexes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19269, https://doi.org/10.5194/egusphere-egu2020-19269, 2020.

Seafloor massive sulfides (SMS) are regarded as a potential future resource to satisfy the growing global demand of strategic metals. Aside from mining and retrieving profitable amounts of massive sulfides from the seafloor, the present challenge is to detect and delineate significant SMS accumulations, which are generally located near mid-ocean ridges and along submarine volcanic arc and backarc spreading centers.

In the past years we have used the marine transient electromagnetic induction system MARTEMIS, a coincident-loop TEM system developed at GEOMAR (Kiel, Germany), in various marine geological settings for the detection and characterization of SMS in the shallow seafloor down to a depth of ~30m. The system was also used in combination with remote EM receivers (Coil2Dipole experiment) to allow for investigations of conductive structures, which are covered by up to ~100m of sediments.

We present experiments from two locations, one at an inactive site in the Mediterranean (Palinuro, Tyrrhenian Sea) where the occurrence of SMS had previously been confirmed by drilling, and one active site on the Northern Mid-Atlantic Ridge (Grimsey Hydrothermal Field, offshore Northern Iceland) where no SMS have been found in gravity cores up to now. The results demonstrate the suitability of the system to detect, delineate and characterize SMS even in scenarios, where the mineralizations are no longer connected to any hydrothermal activity or are buried under a sedimentary cover.

How to cite: Sebastian, H., Amir, H., Reeck, K., and Marion, J.: Electromagnetic experiments for the detection and characterization of seafloor massive sulfides: two case studies from the Mediterranean and Northern Mid-Atlantic Ridge, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19308, https://doi.org/10.5194/egusphere-egu2020-19308, 2020.

EGU2020-19105 | Displays | ERE5.4

Induced polarization and transient electromagnetic surveys for the characterization of a graphite ore

Adrian Flores Orozco, Lukas Aigner, Timea Katona, Matthias Bücker, Philipp Zehetgruber, and Alexander Römer

The prospection of electrical conductors and semi-conductors has been one of the classical applications of the induced polarization (IP) method, with recent laboratory studies permitting to gain a deeper insight into the parameters controlling the polarization response. However, the application of electrochemical models developed for laboratory measurements has been rarely taken into field-scale imaging data sets. To fill this gap, here we discuss IP imaging results collected in Zettlitz (Austria), a former quarry operated between 1855 and 1967 for the extraction of graphite, an electrical conductor. The general goal of the geophysical survey is to characterize the geometry and volume of the residual graphite at the site. To this end, frequency-domain IP imaging measurements were collected along 10 main transects using different geometries, with selected data sets collected in the frequency range between 0.25 and 1 Hz to gain information about the frequency-dependence of the electrical properties. As expected, initial measurements revealed a high IP response in the graphite-rich areas. Nevertheless, the high electrical conductivity of the materials resulted in low voltage readings and an important decrease in the signal-to-noise ratio for deep measurements; thus, significantly reducing the depth of investigation. To overcome this limitation, we conducted measurements at areas of interest using transient electromagnetic (TEM) soundings, which are favored by the high conductivity of the targeted graphite and permit a better delineation of the contact to the calcareous host-rock. Initial analysis of the TEM data revealed a poor consistency with the electrical models retrieved from the IP surveys. However, taking into account the IP effect within the inversion of the TEM data significantly improved the consistency in the subsurface models resolved by the different methods. In order to resolve for adequate parameters for the modeling of TEM signatures, IP measurements were also collected at relevant positions in the frequency-range between 0.01 and 10000 Hz, with a high accuracy electrical impedance spectrometer. Further IP measurements were also collected in rock samples in the laboratory to aid in the interpretation of the field surveys and to permit the numerical modeling of the electrical signatures using a recently proposed electrochemical model. Our results demonstrate that the combination of IP and TEM surveys provide an improved modeling of the field signatures and, thus, a better characterization of the site. Additionally, we discuss the applicability of existing empirical and numerical models for the quantitative interpretation of field surveys.

How to cite: Flores Orozco, A., Aigner, L., Katona, T., Bücker, M., Zehetgruber, P., and Römer, A.: Induced polarization and transient electromagnetic surveys for the characterization of a graphite ore, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19105, https://doi.org/10.5194/egusphere-egu2020-19105, 2020.

EGU2020-18707 | Displays | ERE5.4

Radiation Characteristics of Seismic Source Arrays

Bernd Trabi, Cornelia Tauchner, and Florian Bleibinhaus

Blasting operations in quarries are accompanied by ground vibrations which can endanger buildings nearby. A production blast is made of several holes with a small distance to each other, which are blasted with a time delay, to reduce the ground vibrations. These production blasts produce a specific radiation pattern. It would be favorable to focus the ground vibrations to a less dangerous direction or area. To optimize the radiation pattern of seismic waves the blast configuration can be modified. For the optimization an analytic solution, based on Fourier shift theorem can be used. This assumes a model with a homogeneous half space and similar source wavelets for low frequencies. Because we want to predict the ground vibrations for a more realistic inhomogeneous case, a numerical forward modeling on a 3D model of mount Erzberg was performed with a 3D elastic code with topography. The 3D model of mount Erzberg is the result of a tomographic travel time inversion. One problem is that the spectral response of a single blast is unknown and therefore we had to find a transfer function which transfers the numeric spectral response to the observed spectral response. After applying the transfer function the amplitude spectra of the numeric solution show a good match to the amplitude spectra of the observed production blasts. The main goal is to reduce the ground vibrations at sensitive areas. This is achieved by blasting simultaneously two blast arrays with a greater distance to each other with optimized time delays. To optimize the time delays we developed a global search algorithm, based on Marcov chain Monte Carlo method which finds potential blast configurations, with minimum impact to critical locations nearby the quarry. These blast configurations serve as proposal for real production blasts at mount Erzberg. This study is part of the EU-funded project SLIM (Sustainable Low Impact Mining, www.slim-project.eu).

How to cite: Trabi, B., Tauchner, C., and Bleibinhaus, F.: Radiation Characteristics of Seismic Source Arrays, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18707, https://doi.org/10.5194/egusphere-egu2020-18707, 2020.

EGU2020-22146 | Displays | ERE5.4

SIT4ME: seismic imaging of mineral-hosting structures in Sotiel-Coronada (Spain)

Yesenia Martínez, Juan Alcalde, David Martí, Puy Ayarza, Mario Ruiz, Ignacio Marzán, Fernando Tornos, Alireza Malehmir, Alba Gil, Stefan Buske, Dirk Orlowsky, Imma Palomeras, Juan Manuel Pons, Juan Carlos Videira, Irene De Felipe, and Ramon Carbonell

In order to tackle the ever-increasing demand of raw materials, the European Institute of Technology (EIT) promotes research and innovation solutions for safe and sustainable mineral exploration through its Raw Materials Programme. The SIT4ME project (“Seismic Imaging Techniques for Mineral Exploration”) has been funded as part of this program to develop efficient techniques in seismic acquisition and imaging methods for mineral exploration in crystalline environments. Within SIT4ME, a multidisciplinary data acquisition experiment (i.e. 3D-3C active and passive source seismic datasets) took place in November 2009 in Sotiel-Coronada (Iberian Pyrite Belt, SW Spain). The aim of this experiment was to image a 300-500 m depth pyrite-rich massive sulfide orebody interbedded with felsic volcanic rocks and shales. The seismic dataset involves the recording of 875 vibration points in 653 seismic receivers, distributed in a 3D mesh around the target and six 2D crooked lines. Conventional processing workflow (such as static corrections, surface-consistent deconvolution, amplitude equalization, frequency filtering, and velocity analysis) was combined with more advance methods (e.g. ground roll attenuation or post-stack coherency filtering) to obtain robust images of the subsurface of the target area. The processing workflow has been applied to four 2D seismic sections, one in the North-South and three in the East-West directions, distributed across the study area. The preliminary imaging results show coherent reflective packages down to two seconds two-way traveltime (TWT). The North-South line contains a north-dipping ~400 m long highly reflective zone in the center at 130 ms TWT. The east-west profiles show a slightly folded structure (antiform and synform) which is evident down to 0.25 s TWT. Towards the north, the seismic lines become parallel to subsurface structures and therefore the track of these structures is lost. Current work involves the incorporation of well-log data to improve the quality and resolution of the interpretations. The next processing steps will involve pre-stack depth migration, P-wave travel-time tomography and a combined analysis of controlled source imaging and ambient noise interferometry data.

The SIT4ME project has been funded by EIT Raw Materials (17024).

How to cite: Martínez, Y., Alcalde, J., Martí, D., Ayarza, P., Ruiz, M., Marzán, I., Tornos, F., Malehmir, A., Gil, A., Buske, S., Orlowsky, D., Palomeras, I., Pons, J. M., Videira, J. C., De Felipe, I., and Carbonell, R.: SIT4ME: seismic imaging of mineral-hosting structures in Sotiel-Coronada (Spain), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22146, https://doi.org/10.5194/egusphere-egu2020-22146, 2020.

EGU2020-10911 | Displays | ERE5.4

SIT4ME project: Up-scaling seismic methods for mineral exploration in the Zinkgruvan mining area, Sweden

Alba Gil, Alireza Malehmir, Stefan Buske, Juan Alcalde, Puy Ayarza, Yesenia Martínez, Louise Lindskog, Bill Spicer, Ramon Carbonell, Dirk Orlowsky, Matthew Penney, and Anja Hagerud

Mineral resources are used in large quantities than ever before because they are fundamental to our modern society. To this front and facing an up-scaling challenge, the EIT Raw-Materials funded project SIT4ME (Seismic Imaging Techniques for Mineral Exploration) was launched involving several European institutions. As part of the project, a dense multi-method seismic dataset was acquired in the Zinkgruvan mining area at the Bergslagen mineral district of Sweden, which hosts one of the largest volcanic-hosted massive sulphide (VMS) deposits in the country.

In November 2018, a dense multi-method seismic dataset was acquired in the Zinkgruvan mining area, in a joint collaborative approach among Swedish, Spanish and German partners. A combination of sparse 3D grid and dense 2D profiles in an area of approximately 6 km2 was acquired using a 32t seismic vibrator (10-150 Hz) of TU Bergakademie Freiberg, enabling reasonable pseudo-3D sub-surface illumination. For the data acquisition, a total of approximately 1300 receiver positions (10-20 m apart), using different recorders, and 950 source positions were surveyed. All receivers were active during the data acquisition allowing a combination of 2D and semi-3D data to be obtained for various imaging and comparative studies. The main objective of the study, apart from its commercial-realization approach, was also to provide information useful for deep-targeting and structural imaging in this complex geological setting. The main massive-sulphide bearing horizon, Zinkgruvan formation, is strongly reflective as correlated with the existing boreholes in the mine. Careful analysis of the seismic sections suggests a dominant northeast-dipping structure, consistent with the general plunge of the main Zinkgruvan fold that has been suggested in the area.

Acknowledgements: EIT-RawMaterials is gratefully thanked for funding this up-scaling project 17024.

How to cite: Gil, A., Malehmir, A., Buske, S., Alcalde, J., Ayarza, P., Martínez, Y., Lindskog, L., Spicer, B., Carbonell, R., Orlowsky, D., Penney, M., and Hagerud, A.: SIT4ME project: Up-scaling seismic methods for mineral exploration in the Zinkgruvan mining area, Sweden, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10911, https://doi.org/10.5194/egusphere-egu2020-10911, 2020.

EGU2020-11129 | Displays | ERE5.4

Innovating surface and in-mine seismic exploration solutions

Alireza Malehmir, Lars Dynesius, Paul Marsden, Stefan Buske, Nelson Pacheco, Magdalena Markovic-Juhlin, Bojan Brodic, George Donoso, Tatiana Pertuz, Richard de Kunder, Lukasz Sito, and Christopher Juhlin

Mineral exploration industry needs to push its technological advancement towards finding the so-called critical raw materials. These materials are fundamental for our green technologies and help accelerate the energy transition towards decarbonisation. While in-mine and near-mine exploration will be more convenient in the short term, providing fresh raw materials and mines in greenfield or brownfield areas must not be forgotten in the longer term. As the chase for mineral deposits becomes deeper, seismic methods play a greater role for exploring at depth. Through a series of experiments conducted within the EU-funded Smart Exploration project, we have innovated a number of hardware and methodological solutions for in-mine as well as brownfield seismic exploration. Along with these, legacy data have also been recovered, reprocessed and their values for mineral exploration illustrated. The legacy data examples are from the Ludvika Mines (Nordic Iron Ore AB) of central Sweden and Neves-Corvo (Somincor-Lundin Mining) of southern Portugal.

In particular, through the development of a GPS-time system, we have managed to acquire a globally unique semi3D in-mine and surface seismic dataset at the world-class Neves-Corvo mine. This helped to utilize four exploration tunnels at 600 m depth and two receiver lines on the surface allowing over 1000 recorders to be synchronized for down-tunnel exploration. A broadband electromagnetic-based seismic source (7 kN or 1.5t), developed also in the project, was used as the seismic source.

In central Sweden, at an iron-oxide mining site of Nordic Iron Ore company, 2D seismic profiles helped to suggest potential resources in the down-dip continuation of the known deposits but also in their footwall. A follow-up and more recent survey employed over 1250 seismic recorders and a 32t vibrator to acquire a sparse 2 by 2 km seismic dataset. The data show great quality and allow to image lateral extent of the deposits and crosscutting reflections that may be important factors for mine planning and understanding structural evolution of the deposits. The broadband seismic source was also tested at the site along the existing 2D profiles with raw data already showing a number of reflections interpreted to be from the mineralization. This survey further illustrates that the seismic source functions well and has a great potential for hard rock seismic applications. 

Acknowledgements: This work was supported by the Smart ExplorationTM project. Smart Exploration has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 775971.

How to cite: Malehmir, A., Dynesius, L., Marsden, P., Buske, S., Pacheco, N., Markovic-Juhlin, M., Brodic, B., Donoso, G., Pertuz, T., de Kunder, R., Sito, L., and Juhlin, C.: Innovating surface and in-mine seismic exploration solutions , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11129, https://doi.org/10.5194/egusphere-egu2020-11129, 2020.

EGU2020-3598 | Displays | ERE5.4

2D to 3D high-resolution seismic data conversion: imaging a shallow water metal bearing mine tailings deposit in Portmán Bay, Spain

Emma Soldevila, Ramon Carbonell, David Amblas, and Miquel Canals

High-resolution (HR) 3D seismic acquisition is expensive and often not available due to a variety of reasons. This work builds an optimized workflow to convert a dense 2D HR seismic grid into a 3D seismic volume. The task has been developed within a broader project, NUREIEVA, which aims at characterizing a metal-rich onshore and shallow marine mine tailings deposit in Portmán Bay, Murcia, Spain, which developed from 1957 to 1990. Hence, in the framework of the NUREIEVA project a very dense set of 2D HR seismic lines was acquired. The geophysical equipment used to capture the submarine extent, thickness and internal structure of the mine tailings deposit was a hull-mounted Kongsberg TOPAS PS18 single-channel parametric source. The seismic grid thus acquired consisted of 1309 2D lines, with an approximate distance between lines of 10 m, covering an area of 7.45 km2. The parametric source yielded a vertical resolution of 15 cm, which is very high if compared with conventional seismic reflection data.

 

In order to visualize the internal architecture of the mine tailings deposit in all directions, it is desirable to convert the dense 2D network of lines into a full 3D data volume. Such a data volume is intended to assist reaching faster deposit delimitation and more accurate volumetric calculations. For this purpose, a new optimized 2D to 3D conversion processing flow including a 3D interpolation scheme has been designed. Given the specific characteristics of the input data, a number of challenges had to be addressed, namely: (i) a very high vertical resolution that differs by at least two orders of magnitude from the horizontal resolution; (ii) a large data volume (2 TB), which involves extensive computing time; (iii) the heterogeneity in the acquisition parameters. Because of this, the lines had to be processed previously to the 3D interpolation to homogenize the imaging characteristics and signal content. This new methodology can be now applied for obtaining a 3D volume to any case where a single channel dense 2D seismic grid is available. Furthermore, the new methodology, duly adapted to each particular scenario, represents a low cost alternative to conventional HR 3D seismic and could prevent further seismic shooting in areas when 2D data is already available.

How to cite: Soldevila, E., Carbonell, R., Amblas, D., and Canals, M.: 2D to 3D high-resolution seismic data conversion: imaging a shallow water metal bearing mine tailings deposit in Portmán Bay, Spain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3598, https://doi.org/10.5194/egusphere-egu2020-3598, 2020.

EGU2020-20765 | Displays | ERE5.4

UAS-based hyperspectral and magnetic mineral exploration targeting Ni-PGE mineralization on Northern Disko Island, West Greenland.

Robert Jackisch, Robert Zimmermann, Björn H. Heincke, Arto Karinen, Heikki Salmirinne, Markku Pirttijärvi, Sandra Lorenz, Yuleika Madriz, and Richard Gloaguen

Geologic mapping in arctic regions faces demanding challenges, from accessibility to weather, light and infrastructure conditions. Field expeditions need to cover substantial area, and mostly are supported by satellite and airborne data. While named methods offer large-scaled insights, they often lack the required resolution for precise ground investigations. The rise of unmanned aerial systems (UAS) as new state-of-the-art platform in geoscience provides the means needed to close that scale gap.

Fieldwork within the frame of the EIT project MULSEDRO focused on the Paleocene flood basalt province of Disko Island (West Greenland). On the example of the Qullissat area, we demonstrate how UAS can bring new insights into strategies for magmatic Ni-PGE exploration in the area. Mineralization is associated to basalt sills of the Asuk Member, emplaced locally in coal-bearing cretaceous sandstones.  We conducted photogrammetric outcrop modelling, interpretation of orthoimagery, multi- and hyperspectral based lithological classification and analysis of magnetic data. While magnetics give the location, orientation and subsurface extension of the basaltic sills, spectral imaging, in particular with focus on the iron absorption feature, reveals mineral proxies due to sulphide weathering. A total of 216 line-km for magnetics and 18.5 km2 of multi- and hyperspectral data was covered.

First results show that integration of drone-borne spectroscopic and magnetic data highlights potential local mineralization. Based on our results, possible indications for mineralization are linear features in the first vertical derivative of the magnetic data and specific iron absorptions in the spectral data. Resulting maps are validated using handheld spectroscopy, ground magnetics, susceptibility measurements, combined with geochemistry and mineralogy of rock samples examined in the laboratory. Conclusively, the study solidifies UAS as highly valuable tool for exploration.

How to cite: Jackisch, R., Zimmermann, R., Heincke, B. H., Karinen, A., Salmirinne, H., Pirttijärvi, M., Lorenz, S., Madriz, Y., and Gloaguen, R.: UAS-based hyperspectral and magnetic mineral exploration targeting Ni-PGE mineralization on Northern Disko Island, West Greenland., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20765, https://doi.org/10.5194/egusphere-egu2020-20765, 2020.

EGU2020-18576 | Displays | ERE5.4

PGV-prediction for production blasts at the iron ore mine Mt. Erzberg, Austria

Cornelia Tauchner, Bernd Trabi, and Florian Bleibinhaus

A seismic site characterization of the iron ore mine at Mt. Erzberg was performed in November 2016. The covered area measured about 4 km² within the active mine and the surrounding village. Within 4 weeks 125 3-component-geophones recorded 31 seismic events including production blasts. This data allowed for the computation of P and S velocity models. Which in turn were the basis for seismic wave field modelling with an elastic FD code. These simulations were used to calculate optimized blasting patterns for minimal vibrations at sensitive targets, like settlements and infrastructure, which were tested in a second and third experiment in June and October 19. (see contribution by Trabi et al.) 

In this study a statistical analysis of the resulting PPV-vector at any given geophone position was done, utilizing recorded blasts from 3 experiments. Using a scaled distance method, one can establish relationships between blast intensity, distance and ground vibrations. When compared to the PPV prognosis from the simulations, this analysis allows for assessments on prediction accuracy. General trends in PGV estimation can also be used to create site amplification factors to further enhance optimized blasting pattern calculations. 

This study is part of a large interdisciplinary EU funded project called SLIM, which focuses on sustainability in mining. 

How to cite: Tauchner, C., Trabi, B., and Bleibinhaus, F.: PGV-prediction for production blasts at the iron ore mine Mt. Erzberg, Austria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18576, https://doi.org/10.5194/egusphere-egu2020-18576, 2020.

EGU2020-10719 | Displays | ERE5.4

Sentinel-2 as a tool for mapping iron-bearing alteration minerals: a case study from the Iberian Pyrite Belt (Southern Spain)

Louis Andreani, Erik Herrmann, Sandra Lorenz, Robert Zimmermann, Moritz Kirsch, Naomi Brazzo, and Richard Gloaguen

Satellite-based remote sensing offers a time-saving and cost-effective way of exploring mineral resources in support of mineral exploration and monitoring of mining activities. On one hand, the newest generation of non-commercial optical satellite sensors, such as Sentinel-2, provides data with improved spectral, spatial and temporal resolution. One of the main advantages of Sentinel-2 with respect to other sensors is that it has several bands that cover the 900 nm iron absorption feature. On the other hand, this unique feature still remains underrated as suggested by the lack of applications in the mining sector. We explored the potential of Sentinel-2 for regional-scale mapping of iron-bearing alteration minerals using several approaches commonly used in Earth Observation. We focused on the Iberian pyrite belt, which hosts several of the largest massive sulfide deposits on Earth and has been extensively mined for copper, manganese, iron and gold since the Bronze Age.

First, we attempted to characterize the part of the spectrum between 704 and 945 nm (bands 5 to 9), which is associated to the iron absorption feature, using normalized indices and curve-fitting techniques. These approaches do not require inputs and allow to easily and quickly produce a map of alterations zones revealing mineral prospects and mining sites, but at the cost of a lack of differentiation between the different mineral assemblages. The second approach used was to map specific mineral assemblages using the Spectral Angle Mapper algorithm, which determines the spectral similarity between a known reference spectrum and another unknown spectrum. Relevant mineral assemblages were defined using the mineral composition and resampled spectral signatures from field samples. The focus was mainly set on assemblages containing sericite, chlorite and goethite, which are closely associated to volcanic hosted massive sulfides. Despite known difficulties, related to the low spectral resolution and pixel mixing, several assemblages such as those containing chlorite and sericite could be successfully mapped and their overall distribution appeared consistent with field sampling and hyperspectral imaging from existing studies. Finally, we attempted to map specific mineral assemblages using classification methods based on state of the art machine learning algorithms such as Support Vector Machine, Multi-Layer Perceptron and Random Forrest. Training pixels for mineral assemblages were carefully selected based on field observations and existing hyperspectral data. Each classification method was assessed using a stratified K-fold cross-validation and all four classifications perform well if we consider the average accuracies for alterations, which range from 93.9 to 96.2%.

Sentinel-2 proves to be a powerful tool for mapping iron-bearing minerals. The different approaches we tested (from the simple ones requiring no inputs to the more complex ones requiring field data and knowledge) allow to efficiently map iron-bearing alteration minerals with an increasing degree of details and can find applications not only in mineral exploration but also in monitoring of mining activities.

How to cite: Andreani, L., Herrmann, E., Lorenz, S., Zimmermann, R., Kirsch, M., Brazzo, N., and Gloaguen, R.: Sentinel-2 as a tool for mapping iron-bearing alteration minerals: a case study from the Iberian Pyrite Belt (Southern Spain), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10719, https://doi.org/10.5194/egusphere-egu2020-10719, 2020.

EGU2020-6682 | Displays | ERE5.4

Neotectonics and landscape characterization in the Gawler Craton, South Australia - Insights through high-resolution remote sensing

Cericia Martinez, Ulrich Kelka, Ignacio Gonzalez-Alvarez, and Carmen Krapf

The Gawler Craton hosts significant economic mineralization within South Australia. Due to limited outcrops, deeply weathered profiles, and the absence of a clear variety of landscape surface features, mineral exploration is particularly challenging in this part of Australia. Here we present a workflow of data processing and interpretation to understand the neotectonics and landscape characterization of this region. We explore the potential to delineate surface lineaments and features from newly acquired high-resolution datasets. We aim to automatically identify landform domains based on the analysed data and investigate whether deep seated tectonic lineaments manifest in recognizable surface expressions.

The data we analyse in this study comprises digital elevation, radiometric, magnetic, and gravity data. We assume that elevation and radiometric data relate to surficial landscape features, whereas gravity and magnetic data represent subsurface basement features. Linking the analysis of both surface and subsurface datasets can potentially yield information on the neotectonic activity, and the association between landforms and basement structures as potential zones of fluid migration. We will show how processed digital elevation data can be used for automatic classification of different landform domains.

In order to assess mineral potential zones in the area, we compare the generated lineament data in terms of their geometric and topological properties to examine whether there is consistency in the subsurface and surface layers. We postulate that through a line density map, we may be able to quantify a potential relationship between lineaments that are representative in both the surface and subsurface, indicating potential faults or large-scale lineament trends that may link mineral systems in the basement with the landscape surface features. Areas that exhibit large numbers of surface and subsurface lineaments might be areas of enhanced mineral potential. This study contributes to enhance the efficiency of mineral exploration protocols in areas under cover.

How to cite: Martinez, C., Kelka, U., Gonzalez-Alvarez, I., and Krapf, C.: Neotectonics and landscape characterization in the Gawler Craton, South Australia - Insights through high-resolution remote sensing, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6682, https://doi.org/10.5194/egusphere-egu2020-6682, 2020.

The Horizon 2020 ROBOMINERS project (Grant No. 820971), is developing concepts and prototypes for a bio-inspired, modular and reconfigurable robot-miner for small and difficult to access deposits. This covers both underexplored or currently flooded mines not accessible anymore for conventional mining techniques; or places that have formerly been explored, but whose exploitation was considered non-economic due to the small size of the mineralization or its accessibility.

As part of the sensors payload of the miner, a modular segment of the robot will contain sophisticated geochemical/mineralogical sensors capable of characterising the slurry produced by the drilling process in real-time and interpreting the data as mining diagnostics and navigation parameters for the progression of the miner. This segment will perform in-stream analyses of the drilling slurry using sampling inlet-outlet ports. The sensing techniques currently considered for this segment are LIBS (Laser-induced breakdown spectroscopy), EDXRF (Energy dispersive X-Ray fluorescence), LINF (Laser-induced native fluorescence), Terahertz imagery and time-resolved Raman.

This study presents the first laboratory-scale prototype of this segment, and tests on slurry analogues (bentonite/baryte/salt mixtures of sphalerite ore) with a high-repetition LIBS analyser (1064nm 20 KHz laser, 200-850nm spectrometer, co-axial light collection). As a proof of concept for high-pressure operation, the plasma sparks are created inside the opaque liquid medium using a synchronized argon gas dispenser in front of the laser window. This innovative setup was successfully tested in this study under a pressure range of 1 to 10 bar and a superficial gas velocity range of 50 to 100 mm/s. The next steps in the study is to increase the slurry pressure to simulate deep borehole operation and couple LIBS with a complementary analyser like EDXRF.

How to cite: Burlet, C., Stasi, G., and Vanbrabant, Y.: The ROBOMINERS “advanced mineralogical segment”: an in-stream, in slurry analytical module designed for robotic ore exploration and production, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13102, https://doi.org/10.5194/egusphere-egu2020-13102, 2020.

EGU2020-13121 | Displays | ERE5.4

Exploring geophysical properties of Sn-Cu-Pb-Zn deposits at depth using ROBOMINERS’ mid-perception capability.

Giorgia Stasi, Christian Burlet, Frederic Nguyen, and Yves Vanbrabant

The Horizon 2020 ROBOMINERS project (Grant No. 820971) is developing a modular robot miner prototype following a bio-inspired design, capable of operating, navigating and performing selective mining in a flooded underground environment.

The project has been set up with the long-term strategic objective to facilitate EU access to mineral raw materials – including those that are considered as strategic or critical for the energy transition - from domestic resources and decreasing thus the European import dependency. The use of the robot miner will especially be relevant for mineral deposits that are small or difficult to access.

Conventional DC resistivity and IP methods for geophysical exploration are well reported in the literature, however, in the framework of ROBOMINERS we wants to develop a new approach for DC resistivity and IP that use the deposit itself as a probe for the diffusion of the signal.

Ideally the electrode will be positioned at the end of the robot legs (in contact with the terrain) and the source on the drilling head. This set up will allow to move the source and electrode in preferential position in order to cover the biggest surface possible, and to maximize resistivity measurements avoiding the lack of resolution due to the positioning of electrodes on grounds surface or distant borehole.

In addition to resistivity measurement we are considering an additional technique, namely the Terahertz spectroscopy. The concept for the THz scanning spectroscopy is to use the body of the robot to arrange at 360° the THz detectors and install on the robot’s front the THz source (positioned on a mobile arm or on the drilling head). This technique will allow to scan the mine’s wall and produce a first model of the deposit section. This model will then help for the positioning of the DC/IP source. THz spectroscopy can be applied for the screening of the wall in case it is covered in drilling mud, where regular multispectral camera might not work. As this technique is highly affected by the presence of water is not yet defined its precise field of applicability that will need to be outlined within the project framework.

For our scope we are going to consider (narrow-) vein type and stratiform deposits; those kinds of deposits that could have formerly been explored but their exploitation was considered as uneconomic due to the small size of the deposits or their difficulty of access. More specifically we are going to investigate and review the geophysical properties of tin-lead-zinc wolframite vein type deposit for DC resistivity and IP technique and Terahertz spectroscopy.

2.11.0.0

How to cite: Stasi, G., Burlet, C., Nguyen, F., and Vanbrabant, Y.: Exploring geophysical properties of Sn-Cu-Pb-Zn deposits at depth using ROBOMINERS’ mid-perception capability. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13121, https://doi.org/10.5194/egusphere-egu2020-13121, 2020.

EGU2020-13526 | Displays | ERE5.4

A supervised technique for drill-core mineral mapping using Hyperspectral data

Cecilia Contreras, Mahdi Khodadadzadeh, Laura Tusa, and Richard Gloaguen

Drilling is a key task in exploration campaigns to characterize mineral deposits at depth. Drillcores
are first logged in the field by a geologist and with regards to, e.g., mineral assemblages,
alteration patterns, and structural features. The core-logging information is then used to
locate and target the important ore accumulations and select representative samples that are
further analyzed by laboratory measurements (e.g., Scanning Electron Microscopy (SEM), Xray
diffraction (XRD), X-ray Fluorescence (XRF)). However, core-logging is a laborious task and
subject to the expertise of the geologist.
Hyperspectral imaging is a non-invasive and non-destructive technique that is increasingly
being used to support the geologist in the analysis of drill-core samples. Nonetheless, the
benefit and impact of using hyperspectral data depend on the applied methods. With this in
mind, machine learning techniques, which have been applied in different research fields,
provide useful tools for an advance and more automatic analysis of the data. Lately, machine
learning frameworks are also being implemented for mapping minerals in drill-core
hyperspectral data.
In this context, this work follows an approach to map minerals on drill-core hyperspectral data
using supervised machine learning techniques, in which SEM data, integrated with the mineral
liberation analysis (MLA) software, are used in training a classifier. More specifically, the highresolution
mineralogical data obtained by SEM-MLA analysis is resampled and co-registered
to the hyperspectral data to generate a training set. Due to the large difference in spatial
resolution between the SEM-MLA and hyperspectral images, a pre-labeling strategy is
required to link these two images at the hyperspectral data spatial resolution. In this study,
we use the SEM-MLA image to compute the abundances of minerals for each hyperspectral
pixel in the corresponding SEM-MLA region. We then use the abundances as features in a
clustering procedure to generate the training labels. In the final step, the generated training
set is fed into a supervised classification technique for the mineral mapping over a large area
of a drill-core. The experiments are carried out on a visible to near-infrared (VNIR) and shortwave
infrared (SWIR) hyperspectral data set and based on preliminary tests the mineral
mapping task improves significantly.

How to cite: Contreras, C., Khodadadzadeh, M., Tusa, L., and Gloaguen, R.: A supervised technique for drill-core mineral mapping using Hyperspectral data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13526, https://doi.org/10.5194/egusphere-egu2020-13526, 2020.

EGU2020-13563 | Displays | ERE5.4

Hylite: a hyperspectral toolbox for open pit mapping

Sam Thiele, Sandra Lorenz, Moritz Kirsch, and Richard Gloaguen

Hyperspectral imaging is a powerful tool for mapping mineralogy and lithology in core and outcrops, as many minerals show distinct spectral features in the commonly analysed visible, near, short-wave and long-wave infrared regions of the electromagnetic spectrum. High resolution ground and UAS (unmanned aerial system)-based sensors thus have significant potential as a tool for rapid and non-invasive geological mapping in mining operations, exploration campaigns and scientific research. However, the geometrical complexity of many outcrops (e.g. cliffs, open-pit mines) can result in significant technical challenges when acquiring and processing hyperspectral data. In this contribution we present updates to the previously published MEPHySTo python toolbox for correcting, georeferencing, projecting and analysing geometrically complex hyperspectral scenes. We showcase these methods using datasets covering volcanogenic massive sulphide (VMS) mineralisation exposed within open pit mines in Rio Tinto (Spain), and interpret possible structural and lithological controls on mineralization. Potential applications of hyperspectral mapping for grade control, outcrop mapping and the characterisation of different mineral deposit styles are also discussed.

How to cite: Thiele, S., Lorenz, S., Kirsch, M., and Gloaguen, R.: Hylite: a hyperspectral toolbox for open pit mapping, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13563, https://doi.org/10.5194/egusphere-egu2020-13563, 2020.

The Neoproterozoic Central African Copperbelt located in southern Democratic Republic of Congo (DRC) and the northwestern Zambia and contains 48% of the world’s cobalt reserves and significant resources of copper, zinc, nickel and gold. A good understanding of the geology is critical for successful mineral exploration. However, geological mapping is hindered by low topographic relief, limited outcrop, and a generally deep (10-100m) weathering profile developed since the Late Miocene.  Multielement soil geochemistry provides a means for conducting geological mapping.   Areas with outcrop or containing drill holes and/or trenches were utilized to relate known geological lithologies with soil geochemical results using major element and trace element ratios.

The lithostratigraphy within a study area along the DRC-Zambia border can be geochemically sub-divided into three units. Mixed carbonate and siliciclastic lithologies of the lower portion of the local stratigraphy are typically characterised by elevated V, Ti, and Nb. Mudstones and siltstones are dominated by elevated Al, Fe and Ba. The upper portion of the local stratigraphy is geochemically neutral with regards to trace elements.  Lithological discrimination through analysis of soil geochemical data is limited in some areas by intense weathering. A A-CNK-FM diagram exhibits how complete weathering of carbonate rocks and carbonate-rich breccias (after evaporites) results in the somewhat counter intuitive outcome that residual soils above carbonate rocks are amongst the most aluminum rich in the study area with >80% Al2O3 (mol%) or >80% combined Al2O3 (mol%) and FeO + MgO (mol%). The weathering of siliciclastic rocks (siltstones, mudstones, and diamictites) result in a shorter weathering path across a A-CNK-FM diagram, probably due to their higher original proportion of resistate phases.

An area specific geochemical database of baseline lithostratigraphy weathering paths allows the identification of atypical geochemistry which could indicate facies change, alteration or mineralization.

How to cite: Twigg, H. and Hitzman, M.: Lithostratigraphic Mapping Through Saprolitic Regolith Using Soil Geochemistry and High-Resolution Aeromagnetic Surveys. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20242, https://doi.org/10.5194/egusphere-egu2020-20242, 2020.

ERE5.5 – Sustainable mining and circular economy: waste characterization and exploitation supported by geophysical methods

A landfill body is typically highly heterogeneous. The scale of these heterogeneities - which are relevant for the purpose of assessment of preferential flow paths, the degradation processes, and the spatio-temporally varying aging and settlements - is quite often small considering the limiting resolution and confidence of the prevalent near-surface geophysical methods. High-density areas act as obstruction to fluid flow and are important for understanding the degradation processes. These areas manifest as scatterers in the recorded seismic wavefield. Strong presence of scattered energy is typical of seismic datasets acquired on landfills. Our research has been concentrated on resolving and monitoring density and porosity variations, as well as distribution of water saturation, phreatic surface, matric suction and stress. Dedicated schemes of early-arrival waveform tomography, full-waveform inversion and interferometric seismic wavefield retrieval complemented by electrical resistivity tomography show promise in high-resolution delineation and monitoring of these properties in a heterogeneous landfill. We will discuss the results of a novel inversion scheme which allows quantitative estimation of spatio-temporally heterogeneous matric suction, stress and porosity.

How to cite: Ghose, R.: Characterization of heterogeneous landfill: seismic waveform inversion and wavefield retrieval to integrated quantitative inversion of high-resolution seismic-electrical datasets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18235, https://doi.org/10.5194/egusphere-egu2020-18235, 2020.

EGU2020-20395 | Displays | ERE5.5

Sustainably restoring quarry voids: Geochemically Appropriate Levels for soil recovery activities in Ireland

Mairead Glennon, Vincent Gallagher, Robbie Meehan, Ray Scanlon, Stuart Huskisson, and Graham Webb

What happens to quarries when they are at the end of their productive lifespan? Under Ireland’s waste authorisation regime, worked-out quarries can apply for a licence or permit to accept soil and stone as Soil Recovery Facilities (SRFs). This practice achieves a number of environmental and circular economy objectives, and is allowed for under Ireland’s Waste Management Act 1996 as amended and Waste Management (Facility Permit and Registration) Regulations 2007. Restoring the ground surface of quarries allows the site to be reused for amenity, ecological, agricultural or infrastructural development.  The beneficial recovery of excess excavated soil and stone from other sites represents a saving on the disposal of such material to landfill and in many cases significant reductions in transportation costs and carbon emissions.

Unlike landfills, SRFs are not required to have an engineered basal liner, nor are they required to install an engineered cap following completion of restoration or land-raising. The placement of externally-sourced inappropriate material at SRFs poses a potential source of chemical contamination. Geological Survey Ireland in partnership with the Irish Environmental Protection Agency (EPA) and Geosyntec Ltd have developed an innovative method to assist with the recovery of soil and stone to SRFs while minimising potential chemical impacts. In terms of the source-pathway-receptor conceptual framework, the approach aims to prevent a contaminant source being introduced to the SRF and to prevent the chemical load on the receptor (down–gradient aquifer) from newly placed material exceeding the load from the original or existing soil and stone.

Using existing topsoil geochemical baseline datasets (National Soil Database, Tellus and GEMAS) and site-specific geochemical information from two representative SRFs, a suite of Geochemically Appropriate Levels (GALs) was developed for eight Potentially Harmful metals/metalloids in soil (arsenic, cadmium, chromium, copper, mercury, lead, nickel and zinc). The GALs vary considerably across seven different geological domains in Ireland, reflecting the wide variation in the composition of Ireland’s bedrock and extensive quaternary sediment (subsoil) parent materials. This work addressed the relationship between topsoil and subsoil geochemistry, with data supporting the use of topsoil data as a proxy for subsoil data, in the absence of baseline subsoil geochemical data.

The study is designed to support the EPA and Local Authorities in establishing an approach to setting appropriate trigger levels for acceptance of uncontaminated soil and stone at SRFs and it may be reviewed periodically with improved availability of baseline soil geochemistry data in Ireland, specifically, when Geological Survey Ireland's Tellus topsoil geochemical mapping is completed nationally (projected 2028).

How to cite: Glennon, M., Gallagher, V., Meehan, R., Scanlon, R., Huskisson, S., and Webb, G.: Sustainably restoring quarry voids: Geochemically Appropriate Levels for soil recovery activities in Ireland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20395, https://doi.org/10.5194/egusphere-egu2020-20395, 2020.

EGU2020-10529 | Displays | ERE5.5

Sedimentological and physical properties of the submarine mine tailings deposit of Portmán Bay, SE Spain

Andrea Baza Varas, Jaime Frigola, Marc Cerdà-Domènech, Anna Sànchez-Vidal, and Miquel Canals

Sedimentological and physical properties of the submarine mine tailings deposit of Portmán Bay, SE Spain

 

Andrea Baza-Varas, Jaime Frigola, Marc Cerdà-Domènech, Anna Sànchez Vidal and Miquel Canals

CRG Marine Geosciences, Dept. of Earth and Ocean Dynamics, Faculty of Earth Sciences, University of Barcelona, Spain

a.baza@ub.edu, jfrigola@ub.edu, cerda.domenech@ub.edu, anna.sanchez@ub.edu,  miquelcanals@ub.edu

 

About 57 Mt of mine tailings were dumped directly into the sea from 1957 to 1990 as a result of the open pit exploitation of Pb and Zn ores in Sierra de Cartagena - La Unión district, SE Spain. This led to the infilling of Portmán Bay and a seaward shoreline advance of ~ 600 m associated to the development of a submarine extension of the resulting deposit. Whereas several investigations have been carried out in the emerged portion of the tailings deposit, little information exists on the dimensions and properties of its submerged portion. Nowadays, a restoration project intends to move back the shoreline by ~250 m by dredging part of the subaerial deposit.

 

This contribution focuses on the sedimentological and physical properties of the materials forming the submerged deposit from where accumulation patterns could be derived. With this purpose a number of up to 4 m long gravity cores where obtained from R/V Ángeles Alvariño during the 2018 NUREIEVA-MAR1 research cruise. Subsequently, Multi Sensor Core Logger (MSCL) measurements were performed on whole and split sections in order to obtain the physical properties of the materials, namely gamma-density, magnetic susceptibility, p-wave velocity and non-contact resistivity. Furthermore, split core sections were visually described and imaged.

 

This led to the identification of 4 main units in the sampled materials. From bottom to top, Unit 1 consists of light-colored, bioclast-rich fine-medium sands indicative of pre-dumping inner shelf sedimentation. Unit 2 appears only in some distal cores (~ 1.3 km from shore) collected at water depths of about 40 m and is composed of brown-dark grey silty clays with abundant black patches. All measured physical properties display low and homogeneous values. This unit could be interpreted as of transitional character in between pre-dumping conditions and the first arrival of mine waste. Unit 3 is made of highly laminated clayey silts punctuated by dark sand layers and its physical properties show generally high and oscillating values. Unit 3 corresponds to the mine tailings in stricto sensu. Finally, the upper Unit 4 is composed of bioturbated homogeneous sandy silts with generally diminishing values for most of the measured physical properties. This unit results from the reworking of materials from the top of the tailings deposits mixed with post-dumping sedimentary particles.

 

The physical properties and elements measured have a diagnostic character in differentiating the mine tailings from former deposits and from materials resulting from reworking after the cessation of dumping. Our results also provide clues on the seaward extension of the mine tailings deposit as shown by its seaward thinning recorded in the investigated sediment cores, which is a consequence of increasing distance from the discharge point on the shore and of waste dispersal and accumulation patterns in the shallow marine environment.

How to cite: Baza Varas, A., Frigola, J., Cerdà-Domènech, M., Sànchez-Vidal, A., and Canals, M.: Sedimentological and physical properties of the submarine mine tailings deposit of Portmán Bay, SE Spain, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10529, https://doi.org/10.5194/egusphere-egu2020-10529, 2020.

EGU2020-22598 | Displays | ERE5.5

Surface sealed light weight aggregate from mine tailings

Bjarte Oye, Randulf Hoyli, and Svein Willy Danielsen

Traditionally manufactured light-weight aggregates (LWA) suffer from a fractured surface. Consequently, concrete mixes containing LWA cannot be pumped, due to the water being forced into the porous LWA pellets by the pumping pressure. This is a limitation and a cost factor in construction practise. As part of the project "Nye produkter fra gruveavfall i nord" (Novel products from mine tailings in Northern Norway), will examine mine tailings aiming to develop new products. A pilot study has aimed to develop high quality LWA suitable for pumping from Nussir mining company tailings. In 2019, Nussir ASA was granted operational licence for exploitation of the Repparfjord copper deposit in northern Norway. The tailings, 30 Mtons in total and 1-2 Mtons per year, is deposited in sea.

LWA is traditionally made from pelletized clays, where (Na, K, Mg, Ca, Fe)-aluminosilicates are heated to a viscous glassy phase and subsequently bloated by carbothermal reduction of Fe(III)-oxide, developing carbon monoxide gas inside the pellets. The pellets are then quenched in air, and this is the stage where the surface is fractured. In the pilot study, mine tailings lower in sodium and potassium have been identified, aiming to increase the thermal shock resistance enabling a non-fractured pellets surface. Experimental work was carried out by placing the pellets in a preheated furnace, subsequently quenching pellets at different predetermined times. the results from the study showed that it was possible to produce an unfractured surface, but work is still needed to optimise the bloating. The pellets had an optimal bloating temperature of 1225 °C which is almost 100 °C higher than for typical clay LWAs. Exposure time was ca 5 minutes, a bit shorter than traditional LWAs. The main project will continue the work with a series of new tailings, varying in both composition and particle size.

How to cite: Oye, B., Hoyli, R., and Danielsen, S. W.: Surface sealed light weight aggregate from mine tailings, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22598, https://doi.org/10.5194/egusphere-egu2020-22598, 2020.

EGU2020-8578 | Displays | ERE5.5

Unsupervised delineation of landfill geometries based on geophysical imaging results

Matthias Steiner, Werner Chwatal, Andreas Freudenthaler, and Adrian Flores Orozco

Environmental aspects and the growing interest in the economical exploitation of landfills urges the need for cost-efficient workflows providing information with high spatial resolution. Especially for landfill mining, a detailed characterization of the landfill geometry and the waste composition is critical to assess the economic potential. Geophysical methods have proven to fulfill these requirements since they permit to collect data in a quasi-continuous manner. However, the subjective perception of the geophysical imaging results might bias the interpretation, e.g. the characterization of the landfill boundaries and the estimation of waste volumes. To overcome such shortcomings, we present here an unsupervised method for the post-processing of geophysical imaging to identify subsurface interfaces associated to e.g. landfill geometries, waste variation etc. Our methodology is applicable for results obtained with a single method, or the combination of different geophysical methods, e.g. refraction seismic tomography (RST), electrical resistivity tomography (ERT) or induced polarization (IP). Assuming strong contrasts in the retrieved physical properties associated to interfaces, our method computes the magnitude of the gradient vector for each point in the resolved model. In the next step, a random walker algorithm converts the gradient magnitude image into a binary image permitting to obtain the contours of subsurface regions characterized by high gradients. Originating from the centroid for such a region further base points are determined and used in the final step to compute shape and location of the corresponding interface. To demonstrate the applicability of our method we present here results obtained for a landfill located in Upper Austria, where RST, ERT and IP data were collected along several transects. Our results demonstrate that the method proposed here has the potential to enhance geophysical investigations of landfills by permitting an improved interpretation of the imaging results, as required, for instance to estimate waste volume.

How to cite: Steiner, M., Chwatal, W., Freudenthaler, A., and Flores Orozco, A.: Unsupervised delineation of landfill geometries based on geophysical imaging results, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8578, https://doi.org/10.5194/egusphere-egu2020-8578, 2020.

EGU2020-21855 | Displays | ERE5.5

Combining an integrated geophysical survey into a landfill model: A case study from Emersons Green, UK

Cornelia M. Inauen, Abigail Brooks, David Caterina, Jonathan E. Chambers, Ben Dashwood, Adrien Dimech, Dave A. Gunn, Itzel Isunza Manrique, Oliver Neal, Xavier Piquet, Duncan Scott, Arnaud Watlet, James S. Whiteley, and Paul B. Wilkinson

For a large number of landfills, basic knowledge about extent, waste composition or environmental impact is incomplete. Considering the large number of non-sanitary landfills located in semi-urban areas subject to increased land use pressure plus the high cost for remediation, it is crucial to develop efficient characterization tools suitable in landfill contexts. Such tools are required on a broader level to enable the identification of landfills with high priority for remediation or high potential in terms of waste valorisation (landfill mining) and, on a more detailed level, to enable planning of remediation or landfill mining projects.

Due to the high heterogeneity and complexity of landfills, the application of different geophysical methods in combination with targeted sampling has proven to be a highly favourable approach. In contrast to conventional ground truth methods, geophysical techniques provide the possibility to characterize large portions of the landfill volume in a non-invasive and relatively efficient way. Furthermore, the application of complementary geophysical techniques reduces the risk of misinterpretation, and by verifying/calibrating the results with targeted sampling a relatively detailed landfill model can be built. However, building a landfill model from data measured at different resolution, coverage and with different uncertainties is a challenge.

We present a case study from Emersons Green (UK) where we completed multiple geophysical surveys on a former landfill site prior to its full excavation. The excavation works provided nearly continuous information on the waste and cover layer thickness as well as information on material composition from several locations. This enabled us to validate the geophysical measurements and to test different approaches for model building, as well as testing virtual sampling strategies in order to assess how the number and location of ground truth samples affects the model quality.

The case study has highlighted the advantage of a multi-geophysical approach where Electromagnetics (EM) and Magnetics (Mag) were able to provide a rapid overview of the landfill structure and its lateral extent. In contrast, Induced Polarization Tomography (IPT) and Multichannel Analysis of Surface Waves (MASW) were most suitable to delineate the bottom interface of the waste layer. IPT was in addition able to delineate the cover layer thickness and Electrical Resistivity Tomography (ERT) seemed more sensitive to changes in moisture content. For the model building, a probabilistic approach has proven to be efficient. In terms of sampling strategy a minimum number of samples are required co-located with the geophysical measurements to train the probability model. Furthermore, additional sampling points at locations where geophysical methods are only sparsely available increase the model certainty.

How to cite: Inauen, C. M., Brooks, A., Caterina, D., Chambers, J. E., Dashwood, B., Dimech, A., Gunn, D. A., Isunza Manrique, I., Neal, O., Piquet, X., Scott, D., Watlet, A., Whiteley, J. S., and Wilkinson, P. B.: Combining an integrated geophysical survey into a landfill model: A case study from Emersons Green, UK, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21855, https://doi.org/10.5194/egusphere-egu2020-21855, 2020.

EGU2020-17746 | Displays | ERE5.5 | Highlight

Pressure effects on methane emissions from landfills

Konstantinos Kissas, Charlotte Scheutz, Peter Kjeldsen, and Andreas Ibrom

Landfills are one of the major anthropogenic sources of methane (CH4) emissions to the atmosphere, even years after being inactive. Model-based estimates of CH4 emission from landfills are inaccurate due to uncertainties in the underlying assumptions regarding gas generation rates, oxidation and recovery parameters. In-situ measurement techniques are more reliable in quantifying CH4 emissions, with the tracer gas dispersion method (TDM) being one of the best-validated methods. The TDM does however not allow for continuous estimation unless a higher sampling frequency for longer measurement campaigns is being used. Field studies report short-term CH4 emission variation of several orders of magnitude, which are being driven by changes in meteorological conditions, with changes in barometric pressure being the most important. This variation makes discontinuous measurements more uncertain. In this presentation, we focus on CH4 emission dynamics under the influence of barometric pressure changes and develop a model that can explain the dynamics.

Landfill methane emissions were measured continuously with the eddy covariance method over several months in an inactive landfill (Skellingsted, Western Zealand, Denmark). The landfill is covered with an 80 cm thick soil layer and vegetated with grassland. Screenings of the site indicate a considerable horizontal heterogeneity of the emissions, which needs to be considered when interpreting continuously measured fluxes.

Measured methane fluxes ranged from 0 to 10 μmol∙m-2∙s-1. Periods with decreasing barometric pressure showed highest flux rates, while increasing barometric pressure suppressed the methane flux almost to 0 μmol∙m-2∙s-1. However, this dependency had a complex dynamic nature. In most of the cases, the responses of CH4 fluxes to pressure changes were delayed by 0 to 4 hours. We developed a model concept that is able to explain this behavior, including the pressure gradient driven advective CH4 transports through the porous soil layer above the source and diffusion between fronts of background air and landfill gas.

The general implications from this work are an estimation of the uncertainty and possibly correction of point CH4 emission measurements, e.g. with the TDM. Additionally, the increased understanding of gas transport dynamics through terrestrial landfill covers will help to evaluate the efficiency of methane emission mitigation methods that aim at increasing methane oxidation by the establishment of biocovers.

How to cite: Kissas, K., Scheutz, C., Kjeldsen, P., and Ibrom, A.: Pressure effects on methane emissions from landfills, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17746, https://doi.org/10.5194/egusphere-egu2020-17746, 2020.

EGU2020-20018 | Displays | ERE5.5 | Highlight

Self-burning coal mining residues – an environmental issue or a source of raw materials?

Joana Ribeiro, Isabel Suárez-Ruiz, and Deolinda Flores

The self-burning of coal mining residues disposed at environmental conditions have been described in the literature as a phenomenon occurring worldwide. These coal related fires are of significant concern because of the risks to environment and human health due to the emission of harmful gases and particulate matter to atmosphere. Another concern is the degradation of soils and waters in surrounding areas owing to the mobilization and leaching of hazardous elements. The self-burning of coal mining waste deposits may be a very persistent phenomena over decades. The carbon content (combustible fraction) and chemical composition of coal waste materials (and some physical properties) are the most relevant factors that influence intensity and duration of the self-burning process. The comprehensive characterisation of coal waste deposit materials provide information on the self-burning process and above all useful insights about the propensity to ignition and burning and their environmental impacts. The characterization of coal waste materials can contribute to assess their reuse as a secondary source of critical raw materials and carbon based materials.

The recycling of these materials, from both burning and non-burning coal waste deposits, is in good agreement with recommendations from European Union (EU) pointing out the need for developing sustainable recovery of mining and industrial wastes to mitigate environmental impacts. The EU identifies 26 critical raw materials including inorganic trace elements and natural graphite as a critical raw materials with extremely high level of external dependence, and strongly recommends the development of measures to increase recycling of by-products and residues. In this framework, research has been dedicated to burning or already burned coal mining waste deposits in Portugal and Spain. Non-burning coal mining waste deposits from the same mining areas have also been investigated. These coal waste deposits, resulted from the discharging of coarse mine refuse from mining exploration. They are very heterogeneous and present variable amounts of coal that is the combustible fraction. The comprehensive characterization of mining waste materials as well as the identification of products formed during combustion reveals the potential environmental impact, principally due to the concentration of volatile organic compounds emitted to atmosphere. The combustion process also causes changes in trace elements’ mode of occurrence with some becoming more easily mobilised for surrounding soils and water systems by percolation or deposition of solid atmospheric particles. On the other hand, the mining waste burned materials reveal an enrichment of some trace elements, including critical raw material; and, the production of graphitic structures, including graphene. Therefore the coal wastes mining deposits are an environmental issue, they can be seen as an alternative secondary source of critical raw materials and carbon based materials.

How to cite: Ribeiro, J., Suárez-Ruiz, I., and Flores, D.: Self-burning coal mining residues – an environmental issue or a source of raw materials?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20018, https://doi.org/10.5194/egusphere-egu2020-20018, 2020.

EGU2020-6834 | Displays | ERE5.5

Towards sustainable mining: exploiting raw materials from extractive waste facilities

Giovanna Antonella Dino, Alessandro Cavallo, Ernő Garamvölgyi, Renáta Sándor, and Frederic Coulon

The incremental amount of needed Raw Materials (RM) and Critical Raw Materials (CRM) cannot be totally supplied by recycling activities, and mining activities are growing more and more at global level, requiring more modern and efficient technologies and mining techniques to guarantee a sustainable mining. To reach a sustainable mining, an interdisciplinary approach, which consists in considering economic, environmental and social impacts together with new processes implementation, is needed. The focus of the present research is the exploitation of extractive waste (EW) to recover RM and CRM, considering, the technological and economical factors, together with the environmental impacts, associated to EW quarrying and dressing activities.

The present study, based on a case history from Northern Italy (Montorfano and Baveno granite quarrying area), was intended to validate the presented interdisciplinary approach for evaluating economic and environmental impacts associated to EW facility exploitation (from granite EW facility to products for ceramic industry and by products for building industry and infrastructures). Two different surveys were carried out: in 2009 and 2016, investigating four different EW facilities (Braghini, Ciana-Tane Pilastretto,Sengio, and Montorfano).

A shared methodology was applied to determine EW characteristics (geochemical, petrographycal and mineralogical), EW facility volume (geophysical  and topographic and morphologic 3D characterisation) and potential exploitable products, by-products (and CRM). Meanwhile, the Life Cycle Assessment (LCA) was applied to determine environmental impacts associated to extraction and processing phases.

The sampled materials from the EW facilities, sampled in 2009 and 2016, show highly homogeneous geochemical features (Al2O3: 13.02-14.65; Fe2O3: 1.40-2.41, TiO2: 0.10-0.26, CaO: 0.54-2.01, MgO: 0.14-0.45, K2O: 4.49-5.18, Na2O: 3.08-3.64) for major elements. The alkalies (K2O+Na2O) and Fe2O3tot content of all samples are extremely important for the feldspar (l.s.) industry, and  the samples obtained after magnetic separation show a decrement of Fe2O3 passing from > 1.4% (not good for ceramic industry) to < 0.2% (good for ceramic industry). Moreover, a wider range of geochemical analysis was carried out in 2016 and an interesting fractionation in the treatment process is observed when considering the REE concentration: all samples of the magnetic fraction are much more concentrated than in the feeding material and can be up to one order of magnitude more concentrated than in the upgraded amagnetic portion. The total volume of dumps was estimated in about 2.1 Mm3.

The LCA reports that main environmental loads were due to the dressing plant, including climate change and freshwater eutrophication ones. Despite landfilling shows minor impacts, it has significant impact in terrestrial eco-toxicity. While climate change indicators show significantly higher loads than savings, savings and loads in freshwater eutrophication indicator are balanced. The avoided phosphate and phosphorous release to water results in high ratio of savings in freshwater eutrophication. As for environmental impacts, the SRM recovery activities are favourable for the environment compared to the use of primary sources.

The presented interdisciplinary approach is in line with the will of going towards a sustainable mining, which has to consider, together with economic and environmental factors, also social impacts and risks mitigation instruments.

How to cite: Dino, G. A., Cavallo, A., Garamvölgyi, E., Sándor, R., and Coulon, F.: Towards sustainable mining: exploiting raw materials from extractive waste facilities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6834, https://doi.org/10.5194/egusphere-egu2020-6834, 2020.

EGU2020-10414 | Displays | ERE5.5

Kaolin and quartz from extractive waste: the example of the Monte Bracco area (Piedmont, northern Italy)

Franco Rodeghiero, Cavallo Alessandro, and Giovanna Antonella Dino

The Monte Bracco area (western Alps, northern Italy) is well known for the “Bargiolina” quartzite, a dimension stone that has been exploited in slabs at least since the XIII century, used as internal and external facing, especially in the Baroque. The quarries are located mainly on the top of the Monte Bracco, geologically pertaining to the Dora-Maira Massif, a crystalline massif of the Penninic Domain (Palaeozoic basement and a thin Mesozoic cover). The quartzites occur in sub-parallel lenses (thickness between 2 and 10 m), hosted by ortho- and paragneiss, locally strongly altered in clayey material (kaolinization). The quartzite varieties are characterized by a fine and homeoblastic grain size, a granular – lepidoblastic texture, with regular spaced schistosity, and the main rock-forming minerals are quartz (70 – 90 wt.%), phengite (up to 15 wt.%), K-feldspar (orthoclase, 5 – 10 wt.%, frequently altered in kaolinite) and traces of albite, chlorite and accessory minerals. The quarrying activity boomed between the XIX and the end of the XX century (up to 40 quarries), but the bad exploitation planning in the XX century, which involved the best portions of the rock body, led to partly exploited quarry benches, characterized by a residual yield rate of about 4-8%. At present the quarrying activity is nearly stopped due to low yield rate (and the consequent huge production of waste) and to the competition of the widespread “golden quartzite” from Brazil. The huge amount of quarry waste, the quartz-rich composition and the abundance of kaolin in the altered host gneiss suggest interesting applications as industrial minerals. Due to the high quartz content, the quarry waste (estimated in 2,250,000 m3) could be extracted as a secondary raw material and mineral dressed to obtain products for ceramics, refractories, abrasives and glass manufacturing. The recovery of the kaolinized host gneisses should also be evaluated: the deposit shows proper geochemical, mineralogical and petrographical characteristics for kaolin exploitation, which however should be programmed and carried out together with the exploitation of the quartzite deposit (which lays on the kaolinitic gneiss bench). Preliminary mineralogical and geochemical data (XRPD and XRF) show an appreciable amount of kaolin (8 – 25 wt. %, with a very low Fe2O3 content) in the altered gneisses, and a substantial compositional homogeneity in the different sampled areas. In addition to kaolin, the other main minerals are quartz, K-feldspar and a mixture of phengite and illite, a quite good “raw material” for the ceramic industry. The volume of the kaolinitic gneisses should be further evaluated by targeted field and geophysical surveys, followed by core drilling. In the perspective of a sustainable mining, it is important to move towards the integrated exploitation of the Monte Bracco area, contemporary mining both the quartzite waste and the kaolinitic gneiss (first category materials, industrial minerals), as well as the quartzite benches (second category materials, dimension stone).

How to cite: Rodeghiero, F., Alessandro, C., and Dino, G. A.: Kaolin and quartz from extractive waste: the example of the Monte Bracco area (Piedmont, northern Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10414, https://doi.org/10.5194/egusphere-egu2020-10414, 2020.

EGU2020-16506 | Displays | ERE5.5

Reuse of extractive waste from an abandoned mine site: case study of Campello Monti, Italy

Neha Mehta, Giovanna Antonella Dino, Iride Passarella, Franco Ajmone Marsan, and Domenico De Luca

The progress and prosperity have been based on finite mineral resources and fossil fuels. Sustainable development goals of the United Nations and the implementation of the Paris Agreement, resulted in the vast utilization of a wide range of minerals for green technologies such as low-carbon applications. The global demand for raw materials has increased during the last decades (Kinnunen and Kaksonen, 2019).

In addition to clear economic and societal benefits, mining has also created environmental challenges via significant amounts of mining and quarrying waste termed as extractive waste. However, these wastes can be transformed into valuable secondary metal sources combining metals recovery and environmental management.   

The current study, focuses on reuse and recovery targeted on extractive waste from abandoned mines in Campello Monti. It is a small settlement of Valstrona village in the northern sector of Piemonte, (NW Italy). Geologically, the site is present in the ultramafic layers of mafic complex of Ivrea Verbano Zone and consists of anorthosites, gabbros, gabbro-norite, lherzolites, peridotites, pyroxenites, titanolivin. The area was exploited for nickel production from Fe-Ni-Cu-Co magmatic sulphide deposits from 1865 until 1940s. Currently, the area has waste rock and operating residues dumps.

As, the extractive waste from Campello Monti has not been moved from 1940s and recovery trials have also not been performed. Our study dealt with: (1) reusing fine fraction (<2 mm) of waste rock as soil additive, and (2) recovering raw materials from coarse fraction (>2 mm) of waste rock and operating residues, by means of dressing methods like wet shaking table and magnetic fraction.

The seed germination and plant growth experiments performed using Blok et al. (2008) showed no major detrimental impact on Lepidium sativum plants. Although the plant growth decreased to 31% after adding 45% of waste rock to sand and blonde peat mixture. However, by adding fertilizers this can be mitigated to certain extent.

The coarse fraction of waste rock crushed to <0.5 mm showed recovery of Co, Cu and Ni as 53%, 42% and 66% using shaking table. Whilst, for the same size and dressing method operating residues depicted recovery of Co, Cu and Ni in the range of 55-76%. Whilst, the recovery of these elements varied from 35-41% for operating residues and waste rocks using magnetic separation. The micro-XRF mineral mapping of the concentrates obtained from both dressing methods demonstrated presence of pyroxene, pyrrhotite, olivine, magnetite, pentlandite and chalcopyrite.

The present investigation highlights the methodologies used for obtaining raw materials from extractive waste. Thus moving from the linear economy patterns of mineral extraction to circular closed loops.

References

  1. Blok, C., Perssone, G., and Wever, G. (2008). A practical and low cost microbiotest to assess the phytotoxic potential of growing media and soil. ISHS Acta Horticulturae 779: International Symposium on Growing Media. 10.17660/ActaHortic.2008.779.46.
  2. Kinnunen, P.H.-M., and Kaksonen, A.H. (2019). Towards circular economy in mining: Opportunities and bottlenecks for tailings valorization. J. Clean. Prod. 228, 153–160.

How to cite: Mehta, N., Dino, G. A., Passarella, I., Ajmone Marsan, F., and De Luca, D.: Reuse of extractive waste from an abandoned mine site: case study of Campello Monti, Italy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16506, https://doi.org/10.5194/egusphere-egu2020-16506, 2020.

EGU2020-1585 | Displays | ERE5.5

Development of a sampling protocol for the resource definition of sulphidic Cu-Zn-Pb tailings in an industrial tailings storage facility

Rosie Blannin, Max Frenzel, Raimon Tolosana-Delgado, and Jens Gutzmer

Fine-grained residues of ore processing, known as tailings, are an inevitable product of metal production. Such tailings are typically stored in dedicated Tailings Storage Facilities (TSF). The sedimentary-style deposition of tailings within the TSF results in a structure of sub-horizontal, internally graded layers which heterogeneously concentrate the minerals comprising the residues. Primary depositional structures may be overprinted by subsequent chemical redistribution of minerals and elements during chemical reactions and metal mobilisation. Sulphidic tailings are problematic in terms of the potential for generation of Acid and Metalliferous Drainage, while providing interesting prospects for extraction of recoverable metals. However, efforts to build accurate and reproducible geospatial models of TSFs are hampered by a lack of understanding of how to sample heterogeneous tailings materials in a way that allows the effective characterisation of both the horizontal and vertical variability. This study introduces a sampling protocol for the resource characterisation of TSFs, following the Theory of Sampling. The Davidschacht TSF in Freiberg, Germany, was used as a case study. The Davidschacht TSF was deposited between 1944 and 1969; it contains around 760,000 m3 of Cu-Zn-Pb sulphidic flotation residues originating from the processing of polymetallic hydrothermal vein ores of the Freiberg mining district. A historical drilling campaign of 10 drill holes through the whole depth of the tailings provided a basis for the study. A second drilling campaign of 68 drill holes to a depth of 3 m was carried out on a 30 m grid, and nested grids of 15 m and 7.5 m in the centre of the TSF. The drill cores were logged and a bulk sample was collected for each 1 m section. Representative samples, with 10% randomly selected for duplication, will be analysed with X-Ray Fluorescence for chemical composition and sieving and laser diffraction for particle size distribution. The modal mineralogy, mineral associations and mineral liberation of selected samples will be assessed with the Scanning Electron Microscope-based Mineral Liberation Analyser. A detailed geospatial model of the surface zone of the tailings will be constructed to assess the intrinsic horizontal variability of the TSF. Comparison with the 3D model produced by the previous deep drilling campaign will determine if the sampling and modelling was sufficient to account for the variability of the tailings.

How to cite: Blannin, R., Frenzel, M., Tolosana-Delgado, R., and Gutzmer, J.: Development of a sampling protocol for the resource definition of sulphidic Cu-Zn-Pb tailings in an industrial tailings storage facility, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1585, https://doi.org/10.5194/egusphere-egu2020-1585, 2020.

EGU2020-12763 | Displays | ERE5.5

Overview of a quartz sand deposit and processing plant for the future process alteration

Tamara Kuzmanić and Gordan Bedeković

Quartz sand deposit Ravno is the biggest quartz sand deposit in the Dolenjska region in Slovenia with an area of 1.25 km2. Quartz sand at the site is selectively excavated using mechanical methods. Presently, at the processing plant near the deposit, the main final mineral processing technique is flotation. Prior to the flotation, quartz sand undergoes classification and attrition. Final products produced at the plant are natural sand, washed sand and floated sand.
Recently, mining companies have been turning to simpler processing systems, such as gravity concentration, due to the price increase of floatation reagents, simplicity of the process and lower environmental impact.
Overview of the deposit and current methods used in the processing plant are presented, as a prologue to further work on the process alteration possibilities – a change from flotation to gravity concentration.

How to cite: Kuzmanić, T. and Bedeković, G.: Overview of a quartz sand deposit and processing plant for the future process alteration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12763, https://doi.org/10.5194/egusphere-egu2020-12763, 2020.

EGU2020-10580 | Displays | ERE5.5

Geomorphological mapping as a tool to characterize and manage quarry dump deposits: the case study of Carrara marble basins

Linda Alderighi, Carlo Baroni, and Maria Cristina Salvatore

The peculiar landscape of Carrara (Apuan Alps) is well renown all over the world for the many naturalistic and anthropic landforms which are strictly related to quarrying activity. The valuable white Apuan marble was exploited since the first millennium BC predating the Roman period and was chosen by many artists, as Michelangelo, for their masterpieces. The pluri-millennial quarrying activity left a high density of quarries (among the highest in the world), determining a unique landscape dominated by anthropic landforms including the huge quarry dump deposits, locally called “ravaneti”.

Waste materials from marble quarrying of Carrara basin retain typical textural characteristics closely linked to the different techniques adopted over time for marble extraction. Therefore, quarry dumps represent a key access for reconstructing the evolution of the Apuan marble exploitation. For this reason, ancient ravaneti assume an inestimable value within the historical and cultural heritage of Italy.

In this highly dynamic context, the shape of quarry dump deposits is frequently modified because of their continuous addition and re-exploitation, also due to the necessity of preventing slope processes inducing instability (i.e. debris flows). In fact, during the last decades widespread debris flows frequently affected the area representing serious hazardous events for quarrying activity, infrastructures as well as urban centres.

Here we present the “Geomorphological Map of Ravaneti of Carrara Marble Basins”, developed applying a detailed landscape analysis, updated to 2017, using remote sensing data and field surveys in key sites. All the data were managed in GIS environment and collected into a properly created geomorphological database of the Apuan Alps. The map shows the spatial distribution of quarry dumps according to their geomorphological and sedimentological characteristics.

We identified and quantified the number and the extent of areas affected by natural processes, as debris flows, landslides and running water erosional landforms. Quarry dump deposits were distinguished on the basis of the size of the debris, the weathering of the clasts surface and different vegetal cover degree. The presence and abundance of fine matrix in quarry dump deposits play a relevant role in favouring their stability and in regulating their reservoir effect during intense precipitation events. The geomorphological characterization represents a relevant tool for the monitoring and management of ravaneti suggesting both potentially removable and potentially worthy of geo-conservation quarry dumps on the bases of ì) their historical heritage, ìì) their role in slope instabilities, and ììì) their role in preventing hazardous flooding events, being this sector among the rainiest regions of Europe.

Considering that ravaneti are highly hazardous being widely affected by debris flows, the updated geomorphological data will be relevant for evaluating most susceptible areas and for developing risk assessment models.

 

How to cite: Alderighi, L., Baroni, C., and Salvatore, M. C.: Geomorphological mapping as a tool to characterize and manage quarry dump deposits: the case study of Carrara marble basins, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10580, https://doi.org/10.5194/egusphere-egu2020-10580, 2020.

EGU2020-13801 | Displays | ERE5.5

Ornamental stone cutting processing and sludge production evaluation with the goal of ending waste.

Lorena Zichella, Rossana Bellopede, and Paola Marini

The End-of-waste concept was introduced by the ‘Thematic Strategy on the prevention and recycling of waste’ adopted by the European Commission, in which it proposed to specify the conditions for the cessation of waste status as part of the revision of the Waste Framework Directive (Directive 2008/98/EC). The Directive states that a waste shall lose its status if it is submitted to a recovery operation (including recycling) and comply with specific eligibility criteria. The strategic goal of the End-of-waste is to promote recycling, helping to ensure a high level of environmental protection through the reduction of the consumption of critical raw materials and the quantities of waste destined for disposal.

In the mining sector, the reduction of landfill material may be obtained not only by finding a suitable recovery of the material as a by-product, but also identifying the best available cutting technique to be used on the basis of the physical, chemical and mechanical characteristics of the stones. The choice of the best cutting technique could lead to high efficiency and performance, high quality of the cut surfaces and a very low environmental impact by reducing energy consumption, decreasing the concentration of heavy metals in the sludge and producing less waste.

In this context, an analysis of the procedures for cutting different types of ornamental stones into slabs together with the evaluation of sludge production for the different cutting methods has been carried out.

Three types of analysis were conducted in parallel. The first concerns the characterization of the stones and the choice of the type of cutting machine. The analyses carried out were: petrographic analysis, compression strength, flexural strength, apparent density and water absorption. Also ultrasonic pulse velocity (UPV) and Knoop analyses were performed in order to establish the workability class of the stones, and their classification in accordance with previous research works (EASE R3).

The second analysis involves calculating the amount of sludge produced in the three different cutting technologies, taking into account the same block characteristics. The third analysis was conducted on the sludge resulting from the processing of blocks cut into slabs. A comparison was carried out on the quality of the sludge produced, or type and quantity of metals present, taking into account the three different technologies. The tests carried out were: chemical analysis, magnetic separation test and SEM analysis of the metal fraction.

The study could provide stone producers with a technological, scientific instrument to identify the best cutting techniques for the processing of their stones, in order to obtain a good efficiency process, optimize the recovery process, increase the economic advantages, and evaluate the possible reuse of the sludge through a proactive waste management strategy.

How to cite: Zichella, L., Bellopede, R., and Marini, P.: Ornamental stone cutting processing and sludge production evaluation with the goal of ending waste., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13801, https://doi.org/10.5194/egusphere-egu2020-13801, 2020.

EGU2020-21237 | Displays | ERE5.5

Al-rich industrial residues for mineral binders in ESEE region

Katarina Šter and Sabina Kramar

Al-rich mineral resources are one of the essential components for the production of the novel sustainable mineral binders. Belite-sulfoaluminate (BCSA) cements, which are considered as low-carbon and low-energy, allows the substitution of natural raw materials with secondary ones. In East-Southeast European countries (ESEE) there are huge amounts of various industrial and mine residues that are either landfilled or currently have a low recycling rate. These residues are generated from mining activities (mine waste) and as a by product of different types of industry, such as thermal power plants, steel plants or the aluminium industry (slags, ashes, red mud, etc.). Within the framework of the RIS-ALiCE project, in cooperation with 15 project partners from Slovenia, Austria, France, Hungary, Serbia, Bosnia and Herzegovina and Macedonia, a network of relevant stakeholders has been established in the field of currently unused aluminium-containing mine and industrial residues. Inside the created network mine and industrial residues have been mapped and valorised in order to evaluate their suitability for the use in innovative and sustainable low CO2-mineral binder production. Aluminium-containing residues are characterized with respect to their chemical, physical and radiological composition using different analytical methods such as X ray fluorescence spectroscopy, ICP optical emission spectrophotometry, gravimetry, X ray powder diffraction, gamma spectroscopy, etc. The long-term activity of network between wastes holders/producers and mineral end users will be enabled via developed Al-rich residues registry, including a study of the potential technological, economic and environmental impacts of applying the innovative methodology of the sustainable secondary raw materials management in ESEE region. Developed registry with the data valuable for both, waste providers as waste users in ESEE region, can be later-on upscaled also to other regions of Europe. It will provide the data on the available and appropriate Al-rich secondary resources, which will enablethe production of innovative low-CO2 cements.

Keywords: secondary raw material, alternative binders, Al-rich residues, networking, mapping, valorisation, registry.

How to cite: Šter, K. and Kramar, S.: Al-rich industrial residues for mineral binders in ESEE region, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21237, https://doi.org/10.5194/egusphere-egu2020-21237, 2020.

EGU2020-11681 | Displays | ERE5.5

Landfill investigation using geophysical methods for an improved characterization of the landfill geometry and for assessing microbiological activity

Lukas Aigner, Jakob Gallistl, Matthias Steiner, Christian Brandstätter, Johann Fellner, and Adrián Flores Orozco

The release of landfill gas is responsible for approximately 3 % of the global greenhouse gas emissions. Especially a high content of organic matter in municipal solid waste (MSW) in wet areas may enhance the microbial activity and the production of landfill gas and leachate as metabolic products. Accordingly, the delineation of saturated zones and biogeochemically active and inactive areas is critical for designing adequate stabilization systems to limit the environmental impact of landfills on greenhouse gas production. Therefore, landfill investigations with high spatial resolution are critical for environmental protection. Geophysical methods are a cost-efficient possibility to obtain almost continuous information about subsurface properties at various spatial scales, which can help to identify biogeochemical active zones. Within this case study we investigate the applicability of three geophysical methods, namely (i) the electrical resistivity tomography (ERT), (ii) the induced polarization (IP) method and (iii) the transient electromagnetic (TEM) method to characterize the landfill geometry and to discriminate between biogeochemically active and inactive areas. The investigated landfill is located close to Vienna (Austria) and consists of a mixture of MSW, construction and demolition waste (CDW) and excavated soil. We conducted ERT and IP measurements along 17 profiles distributed over the area of the landfill to provide high resolution images of the subsurface down to 8 m depth. Additionally, we used transient electromagnetic measurements along selected profiles to provide information on deeper structures of the landfill as well as to evaluate the electrical conductivity obtained with ERT. Our results show that the electrical conductivity obtained by both ERT and TEM is mainly sensitive to the increase in the fluid conductivity associated to leachate production and migration. Additionally, a decrease in electrical conductivity is associated to CDW and dry MSW and can help to distinguish between different waste types. However, images of the polarization effect obtained with the IP method, expressed in terms of the phase of the complex conductivity, revealed an improved contrast to characterize variations in the architecture and biogeochemical activity of the landfill. Hence, our study demonstrates that the geophysical methods we applied are well-suited for landfill investigations permitting an improved characterization of landfill geometry and variation in waste composition. In particular, the IP method can delineate between biogeochemically active and inactive zones.

How to cite: Aigner, L., Gallistl, J., Steiner, M., Brandstätter, C., Fellner, J., and Flores Orozco, A.: Landfill investigation using geophysical methods for an improved characterization of the landfill geometry and for assessing microbiological activity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11681, https://doi.org/10.5194/egusphere-egu2020-11681, 2020.

EGU2020-15880 | Displays | ERE5.5

Assessment of magnetic data for landfill characterization by means of a probabilistic approach

Itzel Isunza Manrique, David Caterina, Cornelia Inauen, Arnaud Watlet, Ben Dashwood, Tom Debouny, Thomas Hermans, and Frederic Nguyen

The sustainable vision of the Dynamic Landfill Management (DLM) deals not only with present but also with long-term waste management. In this context, DLM enhances the environmental assessment of landfills after closure as well as the recovery of materials and energy resources, for which, a proper characterization is required. To this end, geophysical methods have demonstrated their suitability for landfill exploration, characterization and monitoring. Due to the complexity of these sites and challenges in data acquisition and/or processing, the use of multiple methods is the best approach for landfill investigations. In this work, we used multiple geophysical methods, co-located with several trial pits and boreholes, to estimate the structure of a waste disposal site located in a quarry, and to better delineate the underlying geology composed of limestone. We applied electrical resistivity tomography (ERT), time-domain induced polarization (IP), H/V spectral ratio from microtremor records and magnetometry. We made a structural joint interpretation using the different datasets and the ground truth data. First, the ERT and IP data were individually inverted, and a first structural model was derived. Afterwards, we followed a parametric analysis of the H/V data to corroborate the thickness of some layers at the position of the seismic stations. Then, this model was used to compute synthetic magnetic data and by comparing them with the observed total field magnetic anomalies, a refined model was produced. We evaluated the improvement of including magnetic modelling by using a probabilistic approach previously reported. This approach is based on the computation of conditional probabilities by comparing the inverted models with the co-located data from trial pits and boreholes. Overall, we delineated the lateral and vertical extension of the waste body, the distribution of ash and lime deposits and estimated the upper limit structure of the bedrock.

How to cite: Isunza Manrique, I., Caterina, D., Inauen, C., Watlet, A., Dashwood, B., Debouny, T., Hermans, T., and Nguyen, F.: Assessment of magnetic data for landfill characterization by means of a probabilistic approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15880, https://doi.org/10.5194/egusphere-egu2020-15880, 2020.

EGU2020-19568 | Displays | ERE5.5

Integrated geophysical imaging of a solid waste landfill (Greater London, UK)

Arnaud Watlet, Cornelia Inauen, Ben Dashwood, Jim Whiteley, Tiphanie Creusel, Itzel Isunza Manrique, David Caterina, Duncan Scott, and Jonathan Chambers

In recent years, increased pressure on land use has underscored the need for characterisation of waste composition and distribution in old landfills. In some cases, a lack of information about waste types and potential leachate migration may also pose risks to the environment. Additionally, the emerging potential for retrieving raw materials from old landfills via enhanced landfill mining has further driven the need for developing better informed landfill inventories. Characterising landfills traditionally relies on two main sources of information: historical reports and ground truth data. However, historical reports on old landfills are not always available or are often incomplete, and relying only on ground truth data (drilling or trenching) is costly and requires extrapolation of, and interpolation between, sparse point-data. Geophysical techniques provide an additional, complementary way for characterising landfills, and a means of non-invasively gathering volumetric information on large portions of the surveyed area. Although, in many cases, the complexity and heterogeneity of the internal structure of the landfill makes it difficult to rely on measurements of one single geophysical property alone.

Here, we present an integrated geophysical survey conducted at a landfill site in the Greater London area. The site consists of a former sand, gravel and clay quarry, which was utilised as a solid waste landfill from the 1940s. The landfill was progressively filled with domestic and commercial waste, reaching a peak in activity in the late 1960s and 1970s. Since the landfill has ceased to operate, the site is now relatively flat, covered by grass and used for horse grazing. Our geophysical campaign comprised a combination of several geophysical techniques including rapid mapping (Electromagnetic Induction, EMI; Magnetometry) and profiling techniques (Electrical Resistivity Tomography, ERT; Induced Polarization; IP; Multichannel Analysis of Surface Waves, MASW). The results show a strong contrast in geophysical character between the eastern and the western side of the surveyed area, attributed to a significant change in waste composition. The geophysical results are compared with two intrusive sampling campaigns comprising a series of boreholes, trial pits and Cone Penetration Tests (CPT). Correlating these ground truth data with the geophysical results allows the identification of different geophysical properties related to distinct waste types, from which it is possible to outline zones of similar waste composition within the landfill site.

How to cite: Watlet, A., Inauen, C., Dashwood, B., Whiteley, J., Creusel, T., Isunza Manrique, I., Caterina, D., Scott, D., and Chambers, J.: Integrated geophysical imaging of a solid waste landfill (Greater London, UK), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19568, https://doi.org/10.5194/egusphere-egu2020-19568, 2020.

EGU2020-7736 | Displays | ERE5.5

Application of a Mise-à-la-Masse approach to detect the leak of water reservoirs

Chengpeng Ling and Andre Revil

Water reservoirs with synthetic geomembranes are widely used for storing water resources and chemical solutions in the agricultures and industries, respectively. Leakages of water reservoirs are respondible for the loss of water resources and the spread of contaminants. It is usually difficult to perceive and localize the leakage of water reseroirs. As a cheap, non-invasive, and non-destructive geophysical technique, the mise-à-la-masse method is used to detect leaks of water reservoirs. In principle, the positive (A) and negative (B) current electrodes are placed inside and outside the reservroir, respectively. A number of voltage electrodes are located around the reservoir and potentials relative to a remote reference potential electrode are measured. In the data processing, a method silimar to the self-potential inversion method is proposed to inverse the voltages recorded around the reservoir. Forward modeling was first carried out to simulate the mise-à-la-masse measurement. A kernel matrix (i.e., the collection of Green’s funstions) from forward modelings was imported to the inverse modeling. In inverse modeling, a global objective function with a data misfit term and regularization term is minimized to invert the measured voltages. An initial model based on the distribution of root mean square values between the observation and the simulation data is first given to the inversion algorithm. A weighting matrix and a minimum support function is used to strengthen the detection resolution of the leak of reservoirs. The distributions of source current density from the inverse modeling are used to provide the best estimated of the positions of leaks. Two laboratory and one field experiments are used to verify the effectiveness and reliability of the mise-à-la-masse method. The results show that the proposed method and inversion algorithm can localize a single leak. For a leak with a crack shape, the inversion algorithm detects the location of the leak with a small bias. Effects of the leak size and an undetected condutive zone on the inversion results are further analyzed. For the side leakage, the inverse algorithm overestimated the depth for a small-size leak, while is slightly underestimated the depth of big leaks. For the bottom leakage, effects of the leak size on inversion results are negligable. An undetected conductive zone could significantly distort the inversion results. This study provides an efficient approach to detect the leakage of reservoirs. In addtion, for the leakage of leachate in landfills or mine tailings, the mise-à-la-masse method is also a promising method.

How to cite: Ling, C. and Revil, A.: Application of a Mise-à-la-Masse approach to detect the leak of water reservoirs, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7736, https://doi.org/10.5194/egusphere-egu2020-7736, 2020.

EGU2020-17610 | Displays | ERE5.5

Evaluating the resource recovery potential of fly ash deposits using electrical and electromagnetic methods

David Caterina, Itzel Isunza Manrique, Hadrien Michel, Christin Bobe, Hugo Lucas, Frédéric Nguyen, and Ellen Van De Vijver

Burning coal, or municipal solid waste, in thermal power plants and in metallurgical industries is responsible for the production of large amounts of combustion residues, which depending on their particle size and density, are usually referred to as fly or bottom ash. Nowadays, they represent one of the main types of industrial waste generated. Although their composition is strongly dependent on the material burned, they typically contain ferro-aluminosilicate minerals with potentially toxic trace elements and inorganic compounds that can cause environmental problems when stored in non-sanitary landfills. At the same time, they also represent an economically interesting secondary resource as they can be valorised by replacing aggregates/additives in cement or ceramics production. Surprisingly, despite the environmental and economic considerations for these materials, their geophysical properties remain largely unknown. A better understanding of their geophysical identity could enable using geophysical methods to, for example, improve the estimation of the volume and quality of recoverable resources from ash deposition sites. In this contribution, we show the results of geophysical investigations carried out in three of these sites located in Belgium. The main geophysical techniques involved are electrical resistivity tomography, time-domain induced polarization and frequency-domain electromagnetic induction. The deposits studied generally exhibit high electrical conductivity presumably due to the high hygroscopy of fly ash, the high chlorides content and the presence of ferro-aluminosilicate minerals, each of which enhancing electrical conduction mechanisms, although the effect of the first two is conditioned by the level of water saturation present. The presence of magnetite, or other ferri- or ferromagnetic materials, may explain the high magnetic susceptibility observed. Yet, while representing a relatively homogeneous type of waste, strong variations in geophysical properties were observed between and within different sites. This suggests a great influence of the ash production process, but also of the site-specific conditions. These first results argue for further field and laboratory experiments to validate the exploratory geophysical survey results and to identify the decisive influencing factors explaining the observed electrical and magnetic response. Improved insight in the geophysical signature of fly ash deposits will allow for more accurate interpretations of geophysical measurements, in its turn providing a more sound basis for guiding conventional sampling design and thereby contributing to a more reliable assessment of the value of these industrial waste landfills in terms of the secondary resources they can deliver.

How to cite: Caterina, D., Isunza Manrique, I., Michel, H., Bobe, C., Lucas, H., Nguyen, F., and Van De Vijver, E.: Evaluating the resource recovery potential of fly ash deposits using electrical and electromagnetic methods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17610, https://doi.org/10.5194/egusphere-egu2020-17610, 2020.

EGU2020-18151 | Displays | ERE5.5

Landfill characterization by multi-method geophysical investigation: the case study of Leppe (Germany)

Tom Debouny, David Caterina, Itzel Isunza Manrique, Pascal Beese-Vasbender, and Frédéric Nguyen

Whether environmental or economic interests are at stake, characterization of landfills is becoming a key operation. Characterization not only concerns old landfills, but also modern engineered landfills where the assessment and monitoring of internal processes such as leachate and biogas generation is of a primary importance. Nowadays, characterization is mostly carried out by conventional invasive methods based on drilling/trenching, sampling and laboratory analyses. Although they provide direct and analytical information, their spatial coverage, or representability, remains a major drawback. In addition, they can be expensive and increase the risk of damaging contamination barriers. Therefore, non- to minimally- invasive characterization geophysical techniques emerge as a complementary option. They allow to better capture the spatial heterogeneity across a site and are more cost-effective than punctual measurements alone. Furthermore, when compared with limited ground truth data, they may provide insights into waste composition, water content or temperature. The present study highlights the added value of a multiple geophysical approach to characterize a landfill located in Engelskirchen in Germany. Leppe landfill was used as a municipal solid waste (MSW) deposit site from 1982 until the end of 2004. Since then, only ash coming from the MSW incineration is discarded, mostly on top of the previous MSW deposit. The combination of geophysical methods used in this study included electrical resistivity tomography (ERT),  induced polarization (IP), multichannel analysis of surface waves (MASW) and horizontal to vertical noise spectral ratio (HVSNR). The 3D ERT and IP model allowed to identify dry zones within the waste (which may have a direct impact on biogas production) and to roughly discriminate the layer of ash from the MSW layer. Seismic velocity model provided by MASW permitted to significantly improve the delineation between the two layers. HVNSR results combined with the information provided by MASW were used to estimate the thickness of the top layer on a larger area using a bilayer hypothesis. These geophysical characterization results were validated with available ground truth data. Overall, in the present case seismic methods showed to be more suited than geoelectrical techniques for the distinction between the ash and MSW layers.

How to cite: Debouny, T., Caterina, D., Isunza Manrique, I., Beese-Vasbender, P., and Nguyen, F.: Landfill characterization by multi-method geophysical investigation: the case study of Leppe (Germany), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18151, https://doi.org/10.5194/egusphere-egu2020-18151, 2020.

EGU2020-18068 | Displays | ERE5.5

Multi-phase geophysical survey to characterise waste materials in a modern engineered landfill site

Ben Dashwood, Cornelia Inauen, Arnaud Watlet, Itzel Isunza Manrique, David Caterina, Simon Loisel, Gaetan Vivien, Jonathan Chambers, and Frederic Nguyen

The future mining potential of a landfill site requires the assessment of the likely volume and distribution of recoverable materials of value, within an overall waste body. Whilst more recently constructed landfill sites may have some record of the type and volume of waste deposited, as well as information concerning the extent of an overall site, there is often scant information available for older landfills. For such sites, the potential for the recovery of waste materials will require some form of rapid characterisation (valorisation) of the waste, such that the cost-effectiveness of any mining operation may be estimated.

Geophysical survey techniques offer the potential to rapidly delineate variations in material properties and may be deployed at a range of scales to suit the dimensions of a site or expected level of heterogeneity within the waste. The majority of geophysical techniques are also non-invasive, which is particularly important where potentially hazardous waste is expected, or where the integrity of environmental protection measures such as geotextile membranes must be maintained.

This case study presents the application of number of geophysical survey techniques to characterise the waste within a filled portion of an active landfill in Normandy, France (Les Champs Jouault) and is a pilot site for the RAWFILL project. The site has been operational since April 2009 and was chosen in part due to the large volume of information concerning the construction and nature of the waste materials deposited. This permitted a reasonably well-constrained interpretation of the geophysical data collected. The site poses a number of interesting issues relating to the fact that the site generates and harvest biogas/methane from the waste materials utilising an injected/recirculated leachate system, with individual waste cells fully sealed with an impermeable geomembrane (liner), which also sits above the waste and is then covered with natural soils. The presence of the liner above the waste prohibited the use of Electrical Resistivity Tomography (ERT) for the geophysical characterisation.

The case study presented used multiple phases of geophysical survey to characterise the solid waste, as well as to target intrusive sampling undertaken at the site. A number of geophysical techniques were applied, including Ground Penetrating Radar (GPR), Electro-Magnetic (EM) and Magnetic techniques, as well as seismic techniques (Multi-channel Analysis of Surface Waves (MASW) and Horizontal to Vertical Signal Ratio (HVSR)). The initial survey provided valuable information concerning the thickness of cover above the geomembrane across the survey area, the extent of individual cells as well as variations in waste condition/composition within individual cells and the overall thickness of waste materials/depth to subgrade/bedrock.

The measured geophysical properties have been used to model both the lateral and vertical extents of the landfill as well as to map the distribution of material properties (potential resource). Preliminary findings were used to target a tranche of intrusive sampling (and further geophysical investigation) designed to ground-truth the geophysical data, with the knowledge gained from this exercise used to valorise the potentially recoverable waste materials present in the form of a Resource Distribution Model (RDM).

 

How to cite: Dashwood, B., Inauen, C., Watlet, A., Isunza Manrique, I., Caterina, D., Loisel, S., Vivien, G., Chambers, J., and Nguyen, F.: Multi-phase geophysical survey to characterise waste materials in a modern engineered landfill site, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18068, https://doi.org/10.5194/egusphere-egu2020-18068, 2020.

EGU2020-22626 | Displays | ERE5.5

The Optical Image Probe as a tool for high resolution site characterisation (HRSC) in landfills - a testcase

Max Vercruyssen, Martijn Naert, Pieter Buffel, Samuel Van Herreweghe, and Herman Brangers

Older landfills are notorious for being vague black boxes. The amount, type and location of the dumped material was rarely or inaccurately recorded. This lack of information can be a problem during redevelopment projects, remining projects and risk assessments for the landfill. To decrease the analytical and spatial uncertainties in the conceptual model of the landfill during these investigations, we need accurate sampling and analysis methods but also sufficient amount of data. A High Resolution Site Characterisation (HRSC) approach is based on measurements and data density that are in the same order of heterogeneity of the site. This approach, that we apply on a daily base in soil contamination projects, was applied in collaboration with Witteveen+Bos on a former landfill site in Flanders. In this project an Optical Image Probe (OIP) combined with Electrical Conductivity (EC) measurements was used with a direct push rig. Using this probe, at a rate of 1 frame each 1.5cm, the subsoil layers were explored with a visual light camera integrated in the probe. The data were studied and compared to landfill trenches to identify the layers. It could be concluded that the probing’s were a good supplement to the trench data. This because of the speed of data acquisition, the less intrusive character and reduced Health and Safety concerns for workers and surrounding.

How to cite: Vercruyssen, M., Naert, M., Buffel, P., Van Herreweghe, S., and Brangers, H.: The Optical Image Probe as a tool for high resolution site characterisation (HRSC) in landfills - a testcase, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22626, https://doi.org/10.5194/egusphere-egu2020-22626, 2020.

EGU2020-20650 | Displays | ERE5.5

Geostatistical inversion of electromagnetic induction data for landfill modelling

João Narciso, Leonardo Azevedo, Marc Van Meirvenne, and Ellen Van De Vijver

The characterization and monitoring of landfills has become a major concern, not only for assessing the associated environmental impact (e.g., groundwater contamination) but also for evaluating the potential for recovery of secondary resources, in particular for the production of raw materials and energy. For both objectives, it is crucial to have knowledge of the waste composition and the current landfill conditions (e.g. water saturation level). Near-surface geophysical surveys have been proven effective for the non-invasive investigation of landfills, in which different methods have been used depending on the specific survey targets.  Because of its sensitivity to two subsurface physical properties, electrical conductivity (EC) and magnetic susceptibility (MS), frequency-domain electromagnetic (FDEM) induction has been successfully applied to the qualitative characterization of urban and industrial landfills, including mine tailings. Yet, due to the generally complex composition and strongly heterogeneous spatial distribution of waste deposits, reconstructing a reliable landfill model from surface geophysical measurements remains challenging. Geostatistical inversion emerges as powerful tool to improve the landfill modelling from geophysical data, allowing for a more detailed description of the spatial distribution of the properties of interest and the associated uncertainty. Additionally, it provides a flexible framework for integrating data from geophysical surveys and conventional sampling from drilling or trenching.

In this work, we present a new geostatistical inversion technique able for the simultaneous inversion of FDEM data for EC and MS, which optimize the landfill modelling procedure and is sensitive towards change on the physical properties of interest. This method is based on an iterative procedure where ensembles of subsurface models of EC and MS are generated with stochastic sequential simulation and co-simulation. These simulated models are conditioned locally by existing borehole data for these properties and by a spatial continuity pattern imposed by a variogram model. Synthetic instrument response data, including both the in-phase and quadrature-phase components of the FDEM response, are generated from each model using a forward model connecting the data domain (FDEM data) with the model domain (subsurface physical properties). The misfit between the observed and forward-modelled FDEM data, weighted according to the depth sensitivity of the FDEM response toward changes in EC and MS, is used to drive the generation of a new set of models in the next iteration. We illustrate the inversion procedure with synthetic landfill example data sets which were created based on real data collected at a mine tailing in Portugal and a municipal solid waste landfill in Belgium.

How to cite: Narciso, J., Azevedo, L., Van Meirvenne, M., and Van De Vijver, E.: Geostatistical inversion of electromagnetic induction data for landfill modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20650, https://doi.org/10.5194/egusphere-egu2020-20650, 2020.

ERE6.1 – Process quantification and modelling in subsurface utilisation

EGU2020-19988 | Displays | ERE6.1

Multi-Scale Simulation of Hydraulic Fracturing and Production: Testing with Comprehensive Data from the Hydraulic Fracturing Test Site in the Permian Basin

Jens Birkholzer, Joseph Morris, John Bargar, Abdullah Cihan, Dustin Crandall, Hang Deng, Pengcheng Fu, Alexandra Hakala, Yue Hao, Adam Jew, Timothy Kneafsey, Christina Lopano, Sergi Molins Rafa, Seiji Nakagawa, George Moridis, Mathew Reagan, Randolph Settgast, Carl Steefel, and Marco Voltolini

The Hydraulic Fracturing Test Site (HFTS) project, fielded a few years ago within the Wolfcamp Formation in the Permian Basin in the United States, provides an excellent opportunity to further develop our understanding of the geomechanical response to hydraulic stimulation and associated production in shale lithologies. In addition to a full set of geophysical and tracer observations, the project obtained core samples from wells drilled through the stimulated region, characterizing the propagation of fractures, reactivation of pre-existing natural fractures, and placement of proppant. In addition to providing an overview of the available field data from the field test, we describe here a multi-scale modeling effort to investigate the hydrologic, mechanical and geochemical response of the Wolfcamp Formation to stimulation and production. The ultimate outcome of this project is the application and validation of a new framework for microscopic to reservoir scale simulations, built upon a fusion of existing high performance simulation capabilities.

The modeling occurs across two spatial domains – the “reservoir scale”, which encompasses the intra- and inter-well regions, and the “inter-fracture scale”, which is the region between stimulated fractures. Physics-based simulations of the fracture network evolution upon stimulation at the reservoir scale using the simulator GEOS provide input for reservoir-scale production simulations conducted with the TOUGH family of codes. At the inter-fracture scale, the fluid dynamics and reactive transport Chombo-Crunch code is used simulate the micro-scale pore-resolved physical processes occurring at the fracture and rock interfaces upon stimulation and production, tested against laboratory studies of proppant transport and pore-scale reactions. Micro-scale modeling and imaging provides upscaled flow and transport parameters for larger-scale reservoir modeling and production optimization.

How to cite: Birkholzer, J., Morris, J., Bargar, J., Cihan, A., Crandall, D., Deng, H., Fu, P., Hakala, A., Hao, Y., Jew, A., Kneafsey, T., Lopano, C., Molins Rafa, S., Nakagawa, S., Moridis, G., Reagan, M., Settgast, R., Steefel, C., and Voltolini, M.: Multi-Scale Simulation of Hydraulic Fracturing and Production: Testing with Comprehensive Data from the Hydraulic Fracturing Test Site in the Permian Basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19988, https://doi.org/10.5194/egusphere-egu2020-19988, 2020.

EGU2020-7387 | Displays | ERE6.1

Coupled Hydro-Mechanical Modeling of Fracture Normal Displacement and Fluid Pressures during a SIMFIP (step-rate injection method for fracture in-situ properties) Test

Alexandru Tatomir, Farzad Basirat, Chin-Fu Tsang, Yves Guglielmi, Patrick Dobson, Paul Cook, Christopher Juhlin, and Auli Niemi

Characterization of coupled hydro-mechanical (HM) processes in rock fractures is important for several key geosciences applications, such as rock slope stability, enhanced geothermal systems, and hydraulic fracturing. In-situ experimentation of these processes is challenging, and presently very few techniques exist for quantifying the parameters needed to calibrate hydromechanical models for fractured rocks at field scales. One recent field technology is the step-rate injection method for fracture in-situ properties (SIMFIP) developed by Guglielmi et al. (2014). The method measures simultaneously the time evolution of flow rate, pressure and three-dimensional deformation of the test interval at high resolution.

In June 2019 a set of SIMFIP experiments was carried out in Åre, Sweden, in the COSC-1 borehole. This is a 2.5 km deep borehole aimed primarily for scientific investigations and the fractures and intact rock sections in the borehole are well characterized. Based on the earlier characterization work, three sections were selected for SIMFIP testing: one intact rock section, one section containing a conductive fracture and one section containing a non-conductive fracture (Niemi et al., in prep.).

In this study, a coupled HM model is developed to represent the key coupled processes occurring during these SIMFIP tests. A fully-coupled vertex-centered finite volume scheme and a decoupled finite element model are implemented independently to simulate the elastic deformations and changes in pressure induced by the step-rate injection or flow back of given water volumes. Specifically, the two models are implemented in the commercial simulator COMSOL Multiphysics (sequentially coupled FEM), and the free-open source academic code DuMuX based on the models of Beck (2019). The models are used to match the pressure recorded by the high precision sensors in the test interval. A parametric study is carried out to mimic the fracture extension and step-down stages of the experiments and to investigate the influence of the key hydromechanical parameters (hydraulic aperture, permeability, storativity, and elastic moduli) on the observed data. The resulting coupled hydromechanical model will be further developed to study the three-dimensional deformation of the borehole section under the SIMFIP test.

 

Beck M (2019) Conceptual approaches for the analysis of coupled hydraulic and geomechanical processes. Ph.D. Thesis, Stuttgart University

Guglielmi Y, Cappa F, Lançon H, Janowczyk JB, Rutqvist J, Tsang CF, and Wang JSY. (2014) ISRM Suggested Method for Step-Rate Injection Method for Fracture In-Situ Properties (SIMFIP): Using a 3-Components Borehole Deformation Sensor. Rock Mech Rock Eng 47:303–311. https://doi.org/10.1007/s00603-013-0517-1

Niemi, Auli, Yves Guglielmi, Patrick Dobson, Paul Cook, Chris Juhlin, Chin-Fu Tsang, Benoit Dessirier, Alexandru Tatomir, Henning Lorenz, Farzad Basirat, Bjarne Almqvist, Emil Lundberg and Jan-Erik Rosberg 'Coupled hydro-mechanical experiments on fractures in deep crystalline rock at COSC-1 – Field test procedures and first results’. Manuscript under preparation, to be submitted to Hydrogeology Journal.

How to cite: Tatomir, A., Basirat, F., Tsang, C.-F., Guglielmi, Y., Dobson, P., Cook, P., Juhlin, C., and Niemi, A.: Coupled Hydro-Mechanical Modeling of Fracture Normal Displacement and Fluid Pressures during a SIMFIP (step-rate injection method for fracture in-situ properties) Test, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7387, https://doi.org/10.5194/egusphere-egu2020-7387, 2020.

EGU2020-429 | Displays | ERE6.1

Mechanical effects of rock cement alteration quantified using digital rock physics

Maria Wetzel, Thomas Kempka, and Michael Kühn

Mineral dissolution is a micro-scale process, which may significantly alter the microstructure of rocks, and consequently affect their effective mechanical behavior at the macro scale. Predicting changes in rock stiffness is of paramount importance within the context of risk assessment for most applications related to geological subsurface utilization, where reduction of mechanical parameters is of particular relevance to assess reservoir, caprock and fault integrity [1].

In the present study, the effective elastic properties of typical reservoir rocks are determined based on micro-computer tomography (micro-CT) scans. The resulting three-dimensional rock geometry comprises a more realistic microstructure regarding the shapes of grains, cements and the overall porous network compared to available empirical approaches. Effective rock stiffness is calculated by a static finite element method, which imposes an uniform strain on the digital rock sample and calculates the resulting stresses. The effect of spatial cement distribution within the pore network is taken into account, considering passive pore filling as well as framework supporting cements. Rock stiffness increases due to the precipitation of pore-filling minerals. This quantitative approach substantially improves the accuracy in predicting elastic rock properties compared to general analytical methods, and further enables quantification of uncertainties related to spatial variations in mineral distribution.

[1] Wetzel M., Kempka T., Kühn M. (2018): Quantifying Rock Weakening Due to Decreasing Calcite Mineral Content by Numerical Simulations. Materials, 11, 4, 542. DOI: http://doi.org/10.3390/ma11040542

How to cite: Wetzel, M., Kempka, T., and Kühn, M.: Mechanical effects of rock cement alteration quantified using digital rock physics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-429, https://doi.org/10.5194/egusphere-egu2020-429, 2020.

Over the last few years, our understanding of the processes involved in the application of Kinetic Interfacial Sensitive (KIS) tracers in two-phase flow as a means to quantify the fluid-fluid interfacial area has been enhanced with the use of controlled column experiments (Tatomir et al. 2015,2018). However, there are still some open questions regarding the effect of immobile water, either as capillary and dead-end trapped water or as a film, and the measured by product concentration at the outflow.

In this study, a new pore-scale reactive transport model is presented, based on the phase-field method, which is able to deal with the KIS tracer interfacial reaction and selective distribution of the by-production into the water phase. The model is validated by comparing the analytical solutions for a diffusion process across the interface and a reaction-diffusion process, and is tested for a drainage process in a capillary tube for different Péclet numbers. The applicability of the model is demonstrated in a realistic 2D porous medium NAPL/water drainage scenario used in the literature. Four case studies are investigated in detail to obtain macroscopic parameters, like saturation, capillary pressure, specific interfacial area, and concentration, for a number of combinations between the inflow rate, the contact angle and diffusivity. We derive a relation between the by-product mass at the outflow and the mobile part of the interfacial area, which is formulated by adding a residual factor. This term relates to the part of the by-product produced by mobile interface that becomes residual in the immobile zones.

How to cite: Gao, H., Tatomir, A., Karadimitriou, N., and Sauter, M.: A phase field method pore-scale model for simulating kinetic interface sensitive tracers reactive transport in porous media two-phase flow systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5460, https://doi.org/10.5194/egusphere-egu2020-5460, 2020.

EGU2020-17719 | Displays | ERE6.1

Speeding up reactive transport simulations: statistical surrogates and caching of simulation results in lookup tables

Marco De Lucia, Robert Engelmann, Michael Kühn, Alexander Lindemann, Max Lübke, and Bettina Schnor

A successful strategy for speeding up coupled reactive transport simulations at price of acceptable accuracy loss is to compute geochemistry, which represents the bottleneck of these simulations, through data-driven surrogates instead of ‘full physics‘ equation-based models [1]. A surrogate is a multivariate regressor trained on a set of pre-calculated geochemical simulations or potentially even at runtime during the coupled simulations. Many available algorithms and implementations are available from the thriving Machine Learning community: tree-based regressors such as Random Forests or xgboost, Artificial Neural Networks, Gaussian Processes and Support Vector Machines just to name a few. Given the ‘black-box‘ nature of the surrogates, however, they generally disregard physical constraints such as mass and charge balance, which are of course of paramount importance for coupled transport simulations. A runtime check of error of balances in the surrogate outcomes is therefore necessary: predictions offending a given tolerance must be rejected and the full physics chemical simulations run instead. Thus the practical speedup of this strategy is a tradeoff between careful training of the surrogate and run-time efficiency.


In this contribution we demonstrate that the use of surrogates can lead to a dramatic decrease of required computing time, with speedup factors in the order of 10 or even 100 in the most favorable cases. Thus, large scale simulations with some 106 grid elements are feasible on common workstations without requiring computation on HPC clusters [2].


Furthermore, we showcase our implementation of Distributed Hash Tables caching geochemical simulation results for further reuse in subsequent time steps. The computational advantage here stems from the fact that query and retrieval from lookup tables is much faster than both full physics geochemical simulations and surrogate predictions. Another advantage of this algorithm is that virtually no loss of accuracy is introduced in the simulations. Enabling the caching of geochemical simulations through DHT speeds up large scale reactive transport simulations up to a factor of four even when computing on several hundred
cores.


These algorithmical developments are demonstrated in comparison with published reactive transport benchmarks and on a real-life scenario of CO2 storage.

 

 

[1] Jatnieks, J., De Lucia, M., Dransch, D., Sips, M. (2016): Data-driven surrogate model approach for improving the performance of reactive transport simulations. Energy Procedia 97, pp. 447-453. DOI: 10.1016/j.egypro.2016.10.047

[2] De Lucia, M., Kempka, T., Jatnieks, J., Kühn, M. (2017): Integrating surrogate models into subsurface simulation framework allows computation of complex reactive transport scenarios. Energy Procedia 125, pp. 580-587. DOI: 10.1016/j.egypro.2017.08.200

How to cite: De Lucia, M., Engelmann, R., Kühn, M., Lindemann, A., Lübke, M., and Schnor, B.: Speeding up reactive transport simulations: statistical surrogates and caching of simulation results in lookup tables, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17719, https://doi.org/10.5194/egusphere-egu2020-17719, 2020.

In the present study, a pre-existing stoichiometric equilibrium model based on direct minimization of Gibbs free energy has been further developed and applied to estimate the equilibrium composition of synthesis gases produced by the gasification of carbon-rich feedstock (e.g., coal, municipal waste or biomass) in a fixed-bed reactor [1]. Our modeling approach is validated against thermodynamic models, laboratory gasification and demonstration-scale experiments reported in the literature. The simulated synthesis gas compositions have been found to be in good agreement under a wide range of different operating conditions. Consequently, the presented modeling approach enables an efficient quantification of synthesis gas compositions derived from feedstock gasification, considering varying feedstock and oxidizer compositions as well as pressures and temperatures. Furthermore, the developed model can be easily integrated with numerical flow and transport simulators to simulate reactive transport of a multi-componentgas phase.

[1] Otto and Kempka, Synthesis gas composition prediction for underground coal gasification using a thermochemical equilibrium modeling approach, Energies (in review)

How to cite: Otto, C. and Kempka, T.: Thermochemical equilibrium modeling approach for carbon-rich feedstock gasification validated against laboratory and large-scale experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18348, https://doi.org/10.5194/egusphere-egu2020-18348, 2020.

EGU2020-6085 | Displays | ERE6.1 | Highlight

Huge subsurface storage potential for excess energy already available in Germany

Michael Kühn, Natalie, Christine Nakaten, and Thomas Kempka

The energy supply in Germany is subject to a profound change. The present paper addresses the German potential for the innovative idea of storing excess energy from renewable power sources in the form of hydrocarbons, which can be used in a closed cycle to produce electricity in an environmentally friendly manner [1].

Excess electricity from wind and sun can be transformed into hydrogen, and with carbon dioxide subsequently into methane until large hydrogen storage capacities become available. When needed, electricity is regained in a combined cycle plant combusting the methane. To close the carbon cycle, carbon dioxide is captured on site. Two subsurface storage formations for both gases are required for the technology [2]. We studied a regional show case for the city of Potsdam and worked out the overall energy and cost efficiency [3]. Our results demonstrate that this extended way of power-to-gas is not only technically, but also economically feasible compared to other state-of-the-art excess energy storage technologies [4].

Here, we are taking into account the actual German storage capacity for natural gas. The most recent development is characterised by stagnation of the available total working gas volume and an increase in the significance of cavern storage at the expense of porous reservoirs. This resulted in the decommissioning of a couple of storage sites within the last years. In view of the fact that natural gas is still second most important for Germany’s primary energy provision, those sites should better be used to store excess energy from renewables instead of their abandonment. We show that the technology to store excess energy in form of methane via power-to-gas is available and ready for operation and that the potential within the German subsurface is enormous. This provides an intermediate option to reduce greenhouse gas emissions while hydrogen storage is still under research and development.

[1] Kühn M. (2013): System and method for ecologically generating and storing electricity. - Patent WO 2013156611 A1

[2] Streibel M., Nakaten N.C., Kempka T., Kühn M. (2013): Analysis of an Integrated Carbon Cycle for Storage of renewables. - Energy Procedia, 40, pp. 202-211

[3] Kühn M., Nakaten N.C., Streibel M., Kempka T. (2014): CO2 Geological Storage and Utilization for a Carbon Neutral “Power-to-gas-to-power” Cycle to Even Out Fluctuations of Renewable Energy Provision. - Energy Procedia, 63, pp. 8044-8049

[4] Nakaten N.C., Chabab E., Kempka T., Kühn M. (2019): An Updated Classification of the Enhanced Power-to-Gas-to-Power Competitiveness Based on Integrated Geological Storage. - 14th Greenhouse Gas Control Technologies Conference Melbourne 21-26 October 2018 (GHGT-14)

How to cite: Kühn, M., Nakaten, N. C., and Kempka, T.: Huge subsurface storage potential for excess energy already available in Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6085, https://doi.org/10.5194/egusphere-egu2020-6085, 2020.

EGU2020-5656 | Displays | ERE6.1

Hydraulic interactions of subsurface reservoirs used for excess energy storage

Jianli Ma, Thomas Kempka, Elena Chabab, Qi Li, and Michael Kühn

Excess electricity produced from renewables can be converted into CH4 by consuming CO2 and H2 by means of the Power-to-Gas (PtG) technology [1]. Previous work indicates that subsurface storage of CO2 and CH4 can meet the projected energy storage requirements [1] [2]. However, gas mixing occurs if both gases are stored in the same reservoir [3], and energy is lost if CH4 is used as cushion gas when both gases are separately stored in different reservoirs [2]. Therefore, an innovative approach to overcome the limitation of aforementioned storage schemes is introduced in this study. For that purpose, the focus is on a double reservoir setting in one anticline system as it is commonly found in, e.g., the Northern German Basin. Here, the confining layer and preexisting or artificial hydraulic connections between the two reservoirs enable the operator to reduce energy losses and avoid gas mixing. We have elaborated a numerical multiphase flow model including the wellbore systems and reservoirs to study the fluid flow and beneficiary effects of pressure interaction between both reservoirs. Based on the geological and operational data of our regional showcase in Germany [4] [5], the energy storage efficiency is quantified, and the potential benefits of the proposed storage scheme are evaluated. It shows that the production of CH4 increases by 68% over twenty years of injection and production. Furthermore, the factors that affect storage efficiency are analyzed to provide information for the optimization of PtG-based subsurface energy storage systems. The simulation can be applied to different geological systems and for parameter sensitivity studies to reduce energy losses and improve storage efficiency.

 

 

Keywords: Power-to-Gas; Subsurface gas storage; Carbon dioxide; Methane

 

[1] Kühn M, Nakaten N, Streibel M, Kempka T. CO2 Geological storage and utilization for a carbon neutral “Power-to-gas-to-power” cycle to even out fluctuations of renewable energy provision. Energy Procedia. 2014; 63:8044-9.

[2] Ma J, Li Q, Kühn M, Nakaten N. Power-to-gas based subsurface energy storage: A review. Renewable and Sustainable Energy Reviews. 2018; 97:478-96.

[3] Ma J, Li Q, Kempka T, Kühn M. Hydromechanical response and impact of gas mixing behavior in subsurface CH4 storage with CO2-based cushion gas. Energy & Fuels, 2019; 33 (7), 6527-6541

[4] Streibel M, Nakaten N, Kempka T, Kühn M. Analysis of an integrated carbon cycle for storage of renewables. Energy Procedia 40 (2013): 202-211.

[5] Kühn M, Streibel M, Nakaten N, Kempka T. Integrated underground gas storage of CO2 and CH4 to decarbonise the “power-to-gas-to-gas-to-power” technology. Energy Procedia 59 (2014): 9-15.

How to cite: Ma, J., Kempka, T., Chabab, E., Li, Q., and Kühn, M.: Hydraulic interactions of subsurface reservoirs used for excess energy storage, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5656, https://doi.org/10.5194/egusphere-egu2020-5656, 2020.

EGU2020-5726 | Displays | ERE6.1 | Highlight

A comparison of the geological potential for methane, hydrogen and compressed air energy storage

Firdovsi Gasanzade, Sebastian Bauer, and Wolf Tilmann Pfeiffer

Energy transition from conventional to renewable energy sources requires large energy storage capacities to balance energy demand and production, due to the fluctuating weather-dependent nature of renewable energy sources like wind or solar power. Subsurface energy storage in porous media may provide the required large storage capacities. Available storage technologies include gas storage of hydrogen, synthetic methane or compressed air. Determination of the spatial dimensions of potential geological storage structures is required, in order to estimate the achievable local storage potential. This study, therefore, investigates the energy storage potential for the three storage technologies using a part of the North German Basin as study region.

For this study, a geological model of the geological subsurface, including the main storage and cap rock horizons present, was constructed and consistently parameterized using available data from the field site. Using spill point analysis potential trap closures were identified, also considering existing fault systems and salt structures for volumetric assessment. Volumetric assessment was performed for each storage site for methane, hydrogen and compressed air, as storage gases and their gas in place volumes were calculated. The effects of uncertainty of the geological parameters were quantified accounting for porosity, permeability and the maximum gas saturation using regional petrophysical models. The total regional energy storage capacity potential was estimated for methane and hydrogen, based on their lower heating values, while an exergy analysis of methane, hydrogen and compressed air was used to compare all available storage technologies. In addition to the storage capacity, also deliverability performance under pseudo-steady state flow condition was estimated for all sites and storage gases.

The results show significant gas in place volumes of about 2350 bcm for methane, 2080 bcm for hydrogen and 2100 bcm for compressed air as a regional gas storage capacity. This capacity is distributed within three storage formations and a total of 74 potential trap structures. Storage sites are distributed rather evenly over depth, with shallow sites at about 400 - 500 m and deep sites reaching depths of about 4000 m. The exergy analysis shows that hydrogen and methane storage technologies have high exergy values of about 15.9 kWh and 8.5 kWh per m³, due to the high chemical part of the exergy, while for compressed air energy storage only the physical part is used during storage and the corresponding value is thus reduced to 6.1 kWh. The total energy storage capacity thus identified of about 32000 TWh of methane and 8400 TWh of hydrogen, with a low estimate of 23000 TWh and 6100 TWh accounting for uncertainty of geological parameters. Thus, the potential is much larger than predicted required capacities, showing that the subsurface storage technologies have a significant potential to mitigate offsets between energy demand and renewable production in a sustainable and renewable future energy system.

How to cite: Gasanzade, F., Bauer, S., and Pfeiffer, W. T.: A comparison of the geological potential for methane, hydrogen and compressed air energy storage , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5726, https://doi.org/10.5194/egusphere-egu2020-5726, 2020.

Storage options for the energy storage in the subsurface includes the injection and storage of the “energy gas” (e.g., methane, hydrogen, compressed air) or thermal water into the underground formations. The heterogeneous structure of the storage formations could play a crucial role on the potential storage capacity, as well as the formulation of post treatment strategy. Hence, innovative techniques are required for characterizing the high-resolution formation heterogeneity and monitoring the gas or heat plume distribution in the subsurface after their injections.  Previous studies have shown that flow properties can vary as the gas or thermal water being injected into the aquifer. In this study, we propose a time-lapse hydraulic tomography (HT) method for characterizing the baseline hydraulic information and depicting the hydraulic property changes through a series of cross-well pumping tests. These tests were implemented in two pilot sites for methane and hot water injection tests at Wittstock, Germany. In order to generate a three-dimensional tomographical configuration, each pumping test was conducted at certain depth in a testing well, accompanying with multiple observation points at other wells. Depth-variant pumping and observation segments were formed by the double-packer system. As a result, we achieved 198 and 135 baseline drawdown curves for the methane and heat sites, respectively. For these measured data, we initially evaluated the effective hydraulic conductivity and specific storage of the aquifer according to certain analytical fitting methods. Furthermore, the vertical anisotropy of the hydraulic conductivity was also estimated. Sequentially, the fitted hydraulic parameters and analytical drawdown curves were utilized for correcting the well skin effects on hydraulic traveltimes and attenuations, as they have an unneglectable impact on them.  The corrected hydraulic traveltimes and attenuations were used for the inversion of the baseline hydraulic diffusivity and specific storage, respectively. Hydraulic conductivity distribution was then estimated through these two parameters. After we achieved the baseline information, HT was executed again by repeating the tomographical pumping tests after methane and hot water injections. The same data processing and inversion techniques were applied to the drawdown curves derived from the post-injection period. Inverted hydraulic diffusivity, specific storage, and hydraulic conductivity were compared to the baseline inversion results. Changes on these hydraulic properties could provide the information of the spatial distribution of methane or heat plume.

How to cite: Hu, L., Somogyvári, M., and Bauer, S.: Utilizing time-lapse hydraulic tomography to characterize the subsurface changes during methane and heat injection experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7766, https://doi.org/10.5194/egusphere-egu2020-7766, 2020.

EGU2020-5598 | Displays | ERE6.1

Performance Evaluation and Operation Mechanism of Deep Borehole Heat Exchanger with Different Types of Boundary Conditions

Wanlong Cai, Chaofan Chen, Fenghao Wang, Jun Liu, Olaf Kolditz, and Haibing Shao

Due to its sustainability, continuity and low carbon emissions, the utilization of geothermal energy is gaining more attention all around the world. Shallow geothermal energy is usually extracted through borehole heat exchangers (BHE) with a maximum length up to 150 m. Such systems typically require large space areas, thus limiting its application in built-up urban areas. This study presents a case where deep borehole heat exchanger (DBHE) with a depth down to 2500 m was constructed to extract geothermal energy for building heating purposes. A double-continuum finite element based numerical model was set up to simulate the heat transport process within and around the DBHE. The model has been validated by the experimental data in a demonstration project located in Fengxi, Xi’an China. The heat extracting performance of DBHE under different types of boundary conditions (including the Dirichlet condition and Neumann condition) are evaluated. The amount of thermal recharges from top, sides and bottom of the domain were differentiated and quantified. It is found that different types of boundary conditions will lead to deviations in the simulated heat fluxes and corresponding thermal recharge. The numerical simulations also suggest that the sustainable heat extract capacity of DBHE is mainly determined by the stored heat from the surrounding subsurface, and thermal recharge takes only a limited contribution. According to the calibrated modelling results, the proper heat extraction rate of DBHE in the long-period operation modes is analyzed.

How to cite: Cai, W., Chen, C., Wang, F., Liu, J., Kolditz, O., and Shao, H.: Performance Evaluation and Operation Mechanism of Deep Borehole Heat Exchanger with Different Types of Boundary Conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5598, https://doi.org/10.5194/egusphere-egu2020-5598, 2020.

Natural gas hydrates, which are ice like crystalline solids, contain tremendous amount of potential hydrocarbon gas. Gas recovery through hydrate dissociation can be achieved through depressurization, inhibitor injection and thermal stimulation. The hydrate dissociation by depressurization involves significant pressure and temperature gradients as the dissociation process is highly endothermic. The destabilization of solid hydrate into fluid constituents causes loss of cementation which can alter the stress field which in turn changes the porosity and permeability of the hydrate bearing medium causing subsidence. In the present study, a thermo-hydro-mechanical-chemical (THMC) coupled numerical simulator is developed accounting for the hydrate phase change kinetics, non-isothermal multiphase flow and geomechanics. The point centered or node centered finite volume method is used for space discretization of flow and energy equations while the finite element method is used for stress equilibrium equation. This procedure requires the flow and mechanics variables to be co-located. The finite volumes are constructed around the flow variables defined at nodes while the finite element is defined by the corner nodes. The volumetric strain rate term in the flow equations, which couples the flow and geomechanics equations, is evaluated by interpolating the volumetric strains calculated over the finite elements to the finite volumes. Our simulations show that this procedure results in a stable convergence of the solution without the need for any stabilizing terms due to co-located variable arrangement. Our simulations also show that the iterative coupled approach, where the flow and geomechanics equations are solved separately and sequentially, gives stable convergence without any additional split terms due to sequential but iterative solving of the coupled equations.

How to cite: Samala, R. and Chaudhuri, A.: Coupled multiphase flow and geomechanics simulation of hydrate dissociation using FVM-FEM co-located variables arrangement, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6745, https://doi.org/10.5194/egusphere-egu2020-6745, 2020.

The recent development of the academic reservoir simulator MUFITS aims its transformation to a universal software package that allows for (a) numerical modelling of non-isothermal multicomponent flows in porous media under wide range of pressures and temperatures, including under critical thermodynamic conditions, (b) history matching of non-isothermal reservoir models, and (c) optimization of thermohydrodynamic processes in porous media.

The extended simulator capabilities for modelling of multicomponent flows includes a new fluid properties module for compositional and thermal reservoir simulations using different cubic equations of state (e.g. Peng-Robinson EoS). An extended library of hydrocarbons, carbon dioxide, nitrogen, water, and other components is built into the simulator, and additional components can be characterized and loaded into the library. An arbitrary number of components can be used in particular simulation. In order to simplify the module usage, the corresponding input data are made compatible with the petroleum industry standards. Unlike many other codes, MUFITS allows for compositional modelling of non-isothermal flows of fluids which properties are predicted with a cubic EoS.

For improved history matching and optimization the simulator is supplied with an external Simulation Control Unit (SCU), which automatically changes certain parameters of the digital reservoir model and reads back the results of the simulations. An external control loop is implemented in SCU. At each iteration of the loop non-isothermal flow in a porous medium is simulated, and the simulation results are used for calculation of the objective function being minimized. In order to accelerate the history matching and optimization, the SCU can simultaneously (in parallel) run several reservoir simulations. The simulator is supplied with the build-in capabilities for the calculation of gravity changes and surface uplift/subsidence which measurements can also be automatically used in history matching.

We complement the new developments with several application examples related to gas condensate fields exploration, carbon dioxide injection in depleted oil reservoirs and gas storages, and natural flows in deep geothermal systems.

We acknowledge the funding from Russian Science Foundation under grant # 19-71-10051.

How to cite: Afanasyev, A., Vedeneeva, E., and Gorokhova, N.: MUFITS: A Universal Reservoir Simulator for Numerical Modelling, History Matching and Optimization of Multicomponent Flows in Porous Media, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11914, https://doi.org/10.5194/egusphere-egu2020-11914, 2020.

EGU2020-7023 | Displays | ERE6.1

Simulation of brine migration along geological fault zones using a consistent mesh approach

Falko Vehling, Firdovsi Gasanzade, Jens-Olaf Delfs, and Sebastian Bauer

Upward brine migration through permeable fault damage zones could endanger near-surface drinking water resources. Deep porous rock formations offer a large potential for gas storage, like e.g. methane or CO2. But gas injection induces formation pressure build up, that can potentially lead to vertical or horizontal brine displacement. Here fault zones play an important role as they can act either as lateral no-flow boundaries or as permeable pathways, that allow for fluid flow and pressure dissipation. Numerical reservoir simulations, which have become an important tool for investigating these effects quantitatively, have to be performed on a regional scale, in order to include the large-scale geological faults zones. Fault zones have to be implemented into the model in a geometrically and hydraulically flexible way, to account for the variety of natural conditions encountered, as e.g. open or closed fault zone.

In order to model that complexity, the corner point grid approach has been applied by geologists for decades. The corner point grid utilizes a set of hexahedral blocks to represent geological formations. At the fault plane, where geological layers are vertically shifted, hanging nodes appear and the corner point grid cannot be used directly, if permeable fault zones have to be represented in the model. In this study we present an extension of a mesh converter, which removes hanging nodes at the fault plane by point combination, thus providing a consistent finite element mesh. Our numerical model can account for heterogeneous hydraulic properties of the fault damage zone and the enclosed fault core. The fault core is represented by one layer of 3D finite elements on each side of the fault plane. The fault damage zone consists of a continuous layer of quadrangular 2D finite elements, which are attached at the outer face of the 3D fault core elements. This model allows for fluid flow along the fault plane while fluid flow through the fault core could be adjusted by element permeability. This concept was implemented into a workflow using the FEM-simulator OpenGeoSys in combination with a mesh converter.

The concept and workflow are shown to run stable using dedicated test cases for method validation, accounting for the coupled transport of water, heat and salt mass for different fault zone setups in a synthetic multi-layered subsurface. Here we focused on brine displacement and uprising due to formation pressure increase after gas injection, which is numerically realized by Dirichlet pressure boundary conditions. Further, we will investigate the relation between computational efficiency and flow solution differences by comparing this concept with the approach of fully discretized faults. Additionally, we will apply our workflow on a real geological case in the Northern German Basin, where a fault system is close to a potential gas storage side.  

How to cite: Vehling, F., Gasanzade, F., Delfs, J.-O., and Bauer, S.: Simulation of brine migration along geological fault zones using a consistent mesh approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7023, https://doi.org/10.5194/egusphere-egu2020-7023, 2020.

Many different scientific open-source and commercial black-box software packages are available for the simulation of fluid flow and transport processes in the geological subsurface. Unfortunately, most of these simulators are limited by tightly integrated chemical modules with insufficient capabilities or the general lack of flexible interfaces applicable for an efficient coupling of third-party chemical libraries. Furthermore, most available open-source numerical frameworks are too complex to be used for educating geosciences students in numerical modelling techniques beyond the general application of ready-for-use simulators to specific modelling challenges. Taking into consideration that the development of a critical perspective of an emerging modeller requires fundamental analysis and understanding of common numerical modelling approaches and pitfalls, scientific source codes written in lower-level programming languages (e.g., FORTRAN, C++ or C) are per se less comprehensible compared to higher-level language implementations (e.g., Python). Hereby, the general lack of proper source code documentation, observed in many scientific open-source numerical codes additionally reduces code readability, and thus hinders code further development by third parties.
To overcome many of these limitations, the TRANsport Simulation Environment (TRANSE) has been developed based on the finite difference method. It allows for a highly flexible integration and coupling of arbitrary processes with thermodynamic and chemical libraries to consider chemical reactions and fluid equations of state. To date, TRANSE solves the pressure-based and density-driven formulation of the Darcy flow equation, coupled with the equations for transport of heat and chemical species on structured grids by simple explicit, weighted semi-implicit or fully-implicit numerical schemes, and is composed of less than 1,000 lines of Python code. A flux-corrected advection scheme can be employed in addition to pure upwinding to minimise numerical dispersion in transport problems dominated by high Péclet numbers.
Just-in-time compilation by means of the Python Numba library results in computational times in the order of equivalent lower-level language implementations (e.g., FORTRAN, C or C++), while CPU-based parallelisation allows for the realisation of high spatial model discretisations. Chemical libraries coupled to TRANSE can be easily parallelised to increase the overall computational efficiency, whereby the latter is especially relevant as chemistry usually represents the main computational bottleneck in reactive transport simulations. Python’s numpy library is used to enable fast and efficient model parametrisation as well as simulation runtime control, whereby the Matplotlib library is employed for automated visualisation. More sophisticated visualisation and post-processing are achieved by using the EVTK library for exporting VTK-compatible data to the interactive software packages VisIt, Mayavi or Paraview. 
The present contribution demonstrates the basic validity of the code implementation by comparison against standard numerical model benchmarks for heat (1D heat diffusion) and fluid flow (Theis problem), advective transport (rotating cone test), density-driven fluid flow (Henry’s and Elder’s problems) as well as available density- and viscosity-driven hydrothermal convection in porous media. A fully coupled application example considering reactive transport of gaseous chemical species at high temperatures is presented.

How to cite: Kempka, T.: Simple and efficient TRANsport Simulation Environment for density-driven fluid flow and coupled transport of heat and chemical species, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18145, https://doi.org/10.5194/egusphere-egu2020-18145, 2020.

ERE6.2 – Induced/triggered seismicity in geo-energy applications: monitoring, modeling, mitigation, and forecasting

EGU2020-9423 | Displays | ERE6.2

Influence of injection parameters on the dynamics of Hydraulic Fracturing monitored by Acoustic Emission

Maria Bobrova, Egor Filev, Anna Shevtsova, Sergey Stanchits, Vladimir Stukachev, and Brice Lecampion

Understanding the processes of Hydraulic Fracturing (HF) initiation and propagation in different types of rocks is important for the design and optimization of HF during the exploitation of underground resources. The main goals were to study the dynamics of the process of hydraulic fracture growth and possible optimization of HF technology for both homogeneous and heterogeneous rocks. Laboratory experiments on HF with different injection parameters were carried out on natural limestone, dolomite and shale specimens. The dynamics of HF process was monitored by Acoustic Emission (AE) technique, on the analogy of induced microseismicity monitoring of HF in the field conditions. The shape of created HF and the size of leak-off zone were analyzed by X-Ray CT scanning technique after the testing.

Experiments on dolomite were conducted using fluids with different viscosities (1000-10000 cP) injected into the rock with a rate of 0.5 ml/min. In case of low viscosity, we observed low AE activity. After the test, the sample was cut in several pieces transverse to the expected fracture plane. We have found that HF has initiated, but did not reach the sample boundaries and leak-off was significant. The ten times increase of fluid viscosity resulted in significantly increased AE activity, smaller size of leak-off zone and higher breakdown pressure (21.8 against 18.7 MPa). The post-test 3D shape of HF surface obtained by X-Ray CT closely correlates with 3D shape of localized AE events, confirming that the fracture propagated in the direction of maximal stress, as expected. It means that viscosity of fracturing fluid had a significant effect on fracturing breakdown pressure and fracture behavior.

The influence of different rock types on hydraulic fracturing was studied with dolomite, limestone and shale samples. In case of dolomite and shale, sufficient number of Acoustic Emission events were recorded, which allowed tracing the direction and dynamics of fracture propagation. However, for the limestone, a very small number of AE events were localized with the same parameters of injected fluid. Comparison of dolomite and shale HFs shows that the crack in the shale had a more complex shape, deviating from the maximal stress direction, which was explained by rock heterogeneity, by the presence of natural cracks and inclined planes of weakness. It led us to conclusion that the rock fabric plays an important role in the behavior of hydraulic fracture in heterogeneous rock.

How to cite: Bobrova, M., Filev, E., Shevtsova, A., Stanchits, S., Stukachev, V., and Lecampion, B.: Influence of injection parameters on the dynamics of Hydraulic Fracturing monitored by Acoustic Emission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9423, https://doi.org/10.5194/egusphere-egu2020-9423, 2020.

EGU2020-7311 | Displays | ERE6.2

Reverse Engineering Earthquakes using Lab-scale Replicas: Application to Mw5.5 2017 Pohang Earthquake

Antoine L. Turquet, Renaud Toussaint, Fredrik K. Eriksen, Eirik Grude Flekkøy, and Knut Jørgen Måløy

An earthquake can happen due to many different phenomena such as sliding faults, fluid/gas injection into the subsurface or volcanic activities. Understanding the cause of earthquakes is one important step towards a better hazard assessment and better mitigation. In this study, we explore the physics behind different types of earthquakes by inducing similar mechanics in lab-scale experiments using an analogous model. Inside a transparent rectangular Hele-Shaw cell, we induce lab-scale microseismicity via pneumatic fracturing. An 80 x 40 cm transparent setup is prepared using a 1 mm thin layer of uncompacted granular medium having a fixed grain size is placed between two glass plates.
The seismic location results are compared with the image correlation results for displacement maps corresponding to the event times. Using air injection, this porous medium is compacted and fractured. This system is monitored using a camera recording 1000 images per second and accelerometers recording with 1 MHz sampling rate. Sources of earthquake-like vibrations are both located using acoustic recordings and image processing. We have observed that the deformation starts with compaction inside the medium; this compaction propagates toward the channel tips and causes the fingers to advance further inside the medium. We have observed (using optics and acoustics) that the movement starts inside the porous medium and progresses toward the channel tips, eventually causing channels to grow further. We also compared the characteristic patterns in these lab-scale events that are very similar to large scale correspondents, in particular with 2017 Mw 5.5 Pohang Earthquake. We reverse-engineered the signature of the recorded lab-scale signals to have a better understanding of this industrial hazard.

How to cite: Turquet, A. L., Toussaint, R., Eriksen, F. K., Flekkøy, E. G., and Måløy, K. J.: Reverse Engineering Earthquakes using Lab-scale Replicas: Application to Mw5.5 2017 Pohang Earthquake, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7311, https://doi.org/10.5194/egusphere-egu2020-7311, 2020.

EGU2020-6195 | Displays | ERE6.2

Imaging Poro-Elastic Effects induced by a Normal Fault Aseismic-to-Seismic Dislocation in Shales

Yves Guglielmi, Jens Birkholzer, Jonathan Ajo-Franklin, Christophe Nussbaum, Frederic Cappa, PierPaolo Marchesini, Michelle Robertson, Martin Schoenball, Chett Hopp, Paul Cook, and Florian Soom

Understanding fault reactivation as a result of subsurface fluid injection in shales is critical in geologic CO2 sequestration and in assessing the performance of radioactive waste repositories in shale formations. Since 2015, two semi-controlled fault activation projects, called FS and FS-B, have been conducted in a fault zone intersecting a claystone formation at 300 m depth in the Mont Terri Underground Research Laboratory (Switzerland). In 2015, the FS project involved injection into 5 borehole intervals set at different locations within the fault zone. Detailed pressure and strain monitoring showed that injected fluids can only penetrate the fault when it is at or above the Coulomb failure criterion, highlighting complex mixed opening and slipping activation modes. Rupture modes were strongly driven by the structural complexity of the thick fault. An overall normal fault activation was observed. One key parameter affecting the reactivation behavior is the way the fault’s initial very low permeability dynamically increases at rupture. Such complexity may also explain a complex interplay between aseismic and seismic activation periods. Intact rock pore pressure variations were observed in a large volume around the rupture patch, producing pore pressure drops of ~4 10-4 MPa up to 20 m away from the ruptured fault patch. Fully coupled three-dimensional numerical analyses indicated that the observed pressure signals are in good accordance with a poro-elastic stress transfer triggered by the fault dislocation.

 

In 2019, the FS-B experiment started in the same fault, this time activating a larger fault zone volume of about 100 m extent near (and partially including) the initial FS testbed. In addition to the monitoring methods employed in the earlier experiment, FS-B features time-lapse geophysical imaging of long-term fluid flow and rupture processes. Five inclined holes were drilled parallel to the Main Fault dip at a distance of about 2-to-5m from the fault core “boundary”, with three boreholes drilled in the hanging wall and two boreholes drilled in the foot wall. An active seismic source-receiver array deployed in these five inclined boreholes allows tracking the variations of p- and s-wave velocities during fault leakage associated with rupture, post-rupture and eventually self-sealing behavior. The geophysical measurements are complemented by local three-dimensional displacements and pore pressures measurements distributed in three vertical boreholes drilled across the fault zone. DSS, DTS and DAS optical fibers cemented behind casing allow for the distributed strain monitoring in all the boreholes. Twelve acoustic emission sensors are cemented in two boreholes set across the fault zone and close to the injection borehole. Preliminary results from the new FS-B fault activation experiment will be discussed.

How to cite: Guglielmi, Y., Birkholzer, J., Ajo-Franklin, J., Nussbaum, C., Cappa, F., Marchesini, P., Robertson, M., Schoenball, M., Hopp, C., Cook, P., and Soom, F.: Imaging Poro-Elastic Effects induced by a Normal Fault Aseismic-to-Seismic Dislocation in Shales, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6195, https://doi.org/10.5194/egusphere-egu2020-6195, 2020.

EGU2020-9681 | Displays | ERE6.2

Characterising induced acoustic emission activity observed during a mine-scale hydraulic-fracturing experiment in anisotropic crystalline rock

Carolin Boese, Grzegorz Kwiatek, Georg Dresen, Joerg Renner, Thomas Fischer, and Katrin Plenkers and the STIMTEC Team

Between early 2018 and late 2019 the STIMTEC hydraulic stimulation experiment was performed at ca.~130 m below surface at the Reiche Zeche research mine in Freiberg, Saxony/Germany. The project aims at gaining insight into the creation and growth of fractures in anisotropic and heterogeneous crystalline rock units, to develop and optimise hydraulic stimulation techniques for EGS applications and to control the associated induced seismicity under in situ conditions. A series of ten hydro-frac experiments were performed in a 63 m-long, 15°-inclined injection borehole and five mini-fracs for stress measurements in a sub-vertical borehole. These were monitored using a seismic monitoring system of twelve high-sensitivity Acoustic emission (AE) sensors, three accelerometers and one broadband sensor. More than 11,000 high-frequency AE events with source sizes on the cm-to-dm scale accompanied the hydraulic stimulation in five of ten stimulated intervals in the injection borehole. Several hundred AE events were recorded during the mini-fracs in the vertical borehole. We investigate the characteristics of induced AE events by combining information obtained from high-accuracy event locations using a transversely isotropic P-wave velocity model per station with station corrections, relative hypocentre locations, and focal mechanism solutions of selected events. The AE event clouds extend ca. 5 m radially from the injection points and show variying orientations and dips. The ca. 150 focal mechanism solutions obtained using P-wave polarisations display mixed-mode failure with a significant portion of them showing compaction. The orientation of the maximum principal stress inferred from the hydro-fracs in the injection and vertical boreholes has a trend of N348°E and a plunge of 20°, as typical for southeast Germany. However, discrepancies in the magnitudes of the principal stresses were measured between these boreholes ca. 15 m apart, resulting in different faulting regimes. We present stress orientations obtained from inverting focal mechanism solutions to provide additional information for interpreting stress-characterisation measurements.

How to cite: Boese, C., Kwiatek, G., Dresen, G., Renner, J., Fischer, T., and Plenkers, K. and the STIMTEC Team: Characterising induced acoustic emission activity observed during a mine-scale hydraulic-fracturing experiment in anisotropic crystalline rock, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9681, https://doi.org/10.5194/egusphere-egu2020-9681, 2020.

On 30 November 2018, three felt earthquakes occurred in quick succession close to the city of Fort St. John, British Columbia, likely as a direct response to a hydraulic fracturing operation in the area. Events appear tightly clustered spatially within the upper 10 km of the crust. Hypocenters locate at the confluence between a large scale reverse faulting regime (in the north-west, probably due to the influence of the Rocky Mountain fold and thrust belt) and an oblique strike slip faulting regime (in the south-east, probably due to the influence of the Fort St. John Graben), resulting in a variety of focal mechanisms and a very complex local stress regime. Further analysis of the principal stresses suggests that σ1 is well constrained and close to horizontal, whereas σ2 and σ3 are poorly constrained, and can alternate between the horizontal and the vertical plane. Here, we present an overview of the temporal and spatial evolution of this seismic sequence and its relationship to hydraulic fracturing operations in the area, and examine the influence of large-scale regional tectonic structures on the generation of seismicity on this occasion.

 

How to cite: Salvage, R. O. and Eaton, D. W.: Hydraulic fracturing operations within an extremely complex stress regime: The case of Fort St. John, British Columbia, Canada, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5702, https://doi.org/10.5194/egusphere-egu2020-5702, 2020.

EGU2020-10955 | Displays | ERE6.2 | Highlight

A decade of Oklahoma earthquakes: past, present and future

Xiaowei Chen, Guang Zhai, Manoochehr Shirzaei, and Yan Qin

In the last decade, Oklahoma has experienced significant changes in earthquake activities: earthquake rate dramatically increased since 2009, with a peak rate exceeding California, which has gradually decreased in recent years. This “accidental” large scale earthquake experiment provides us with rich datasets to further understand earthquake physics. Here, focusing on analyses of seismicity and accounting for the physics of earthquake nucleation, we link several studies to give a brief overview of Oklahoma earthquakes, and their implications for future studies in induced seismicity.  First, the analysis of spatiotemporal patterns of seismicity rate can help us infer the subsurface hydraulic parameters at both regional and local scales. At the regional level, the hydraulic diffusivities differ between Eastern and Western Oklahoma, separated by the Nemaha Fault, reflecting hydraulic properties of the Arbuckle Group (injection layer). At local scales within individual faults, the analysis suggested similar hydraulic diffusivities to crustal earthquake bursts from other tectonic regions, implying common properties of the crystalline basement.  Second, coupled poroelastic responses to injection on individual faults are essential, and produce seismicity rate forecast that more closely resemble observations. However, local stress tensor variations can significantly influence fault “criticality” and should be taken into account for modeling stress interactions. Third, in addition to injection-related stress changes, earthquake interactions and aseismic slip need to be considered in induced earthquake sequences, and detailed source modeling and statistical analysis are required to understand their roles in the evolutions of individual sequences further. Finally, Oklahoma seismicity offers opportunities to test short- to intermediate-term forecasting based on different physical models, and new windows into earthquake rupture initiations.

How to cite: Chen, X., Zhai, G., Shirzaei, M., and Qin, Y.: A decade of Oklahoma earthquakes: past, present and future , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10955, https://doi.org/10.5194/egusphere-egu2020-10955, 2020.

Xiluodu is currently the third largest hydropower station in the world and situates on the upper Yangtze River in Southwestern China. The 285.5 m-high dam lies in the center of a relatively intact and stable tectonic block, triangulated by three large fault zones. The seismicity in the region increased markedly since the reservoir was first impounded in 2013. Previous studies suggest a strong spatial-temporal link between the seismicity and reservoir impoundment. This study attempts at conducting a quantitative analysis integrating the geological and engineering data to constrain the link between the impoundment and the seismicity, which could inform the future seismic evolution in the area.

We first study the characters of the spatial activity of earthquakes in different periods to address the correlation between increased seismicity and reservoir impoundment. Since the impoundment, the earthquakes in this region can be plausibly separated spatially into two groups. The first group (including a ML5.4 and a ML5.5 event) is located within ~10km of reservoir, where a major fault zone is absent. Within this spatial range,  earthquakes > ML 2.0 are rare three years prior to the impoundment, but more than 1000 events were detected between the initial impoundment in 2013  and September 2014 when the reservoir reached its peak level. Thereafter, the fluctuations of water level were accompanied by continuous seismicity, albeit at a considerably lower rate. The seismicity in this region is strengthened again in 2019. The other group of earthquakes are clustered with several mapped major fault traces. Some of these events quickly followed the water level fluctuation, while some were observed after significant delays. In general, the distances between locations of delayed events and the reservoir gradually increase with time. 

To address the influence of impoundment on seismicity, we analyzed the hydrologic and mechanical effects of the impoundment, i.e., the fluid pressure diffusion and the reservoir loading. We computed the spatiotemporal changes of Coulomb stress on known faults resulting from these two effects. The sensitivity analysis of hydraulic and mechanical parameters shows that the changes of Coulomb stress in the area could increase to a level that is relevant to reactivation of faults. While the relationship between the impoundment and increase seismicity warrants further analysis, we hope to inform the regional seismic impact by integrating in-situ stress state, fault geometries, and the coupled hydro-mechanical stress changes.

How to cite: Zhang, M., Ge, S., Yang, Q., and Ma, X.: Reservoir impoundment, hydro-mechanical changes, and increased seismicity near the Xiluodu hydropower dam, Southwestern China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7618, https://doi.org/10.5194/egusphere-egu2020-7618, 2020.

EGU2020-19749 | Displays | ERE6.2

Induced earthquakes at the carbon sequestration site Carbfix2, Hellisheiði, Iceland

Vala Hjörleifsdóttir, Gunnar Gunnarsson, Sigríður Kristjánsdóttir, Bergur Sigfússon, Halldór Geirsson, Kristín Jónsdóttir, Ingvi Gunnarsson, and Kristján Ágústsson

The 303 MW Hellisheiði, Iceland geothermal power plant was commissioned in 2006 and in early September 2011, reinjection of geothermal fluid was initiated in the second reinjection site of the plant; Húsmúli.  The site has 5 injection wells in operation, with depths of over 2000 m and a total of up to 500 l/s of fluid being reinjected into the site.  Seismicity had previously been observed in the region, including both natural seismicity before power plant operations started (e.g. Foulger et al., 1988) and induced seismicity during drilling of the injection wells (Ágústsson et al., 2015).  The reinjection caused severely increased level of seismicity within days, with two earthquakes of M 4.0 and M3.9 respectively, occurring a little over a month after the start of reinjection (Icelandic Meteorological Office catalog). The injection was also accompanied by uplift of approximately 2 cm (Juncu et al., 2018).  Due to the increased level of seismicity, a committee was formed and several measures on how to control it were suggested – including starting reinjection gradually after it has been stopped (Bessason et al., 2012).

In 2014, as a part of the Carbfix2 project, the reinjection fluid in Húsmúli was combined with gas, and CO2 and H2S, previously being released into the atmosphere, is now captured and reinjected into the basaltic formation (Matter et al., 2016, Gunnarsson et al., 2018).  It is estimated that the CO2 and H2S are crystalized into calcite and pyrite in under 2 years (Gunnarsson et al., 2018). This project has been very successful and is currently capturing and permanently storing an estimated 33% of the CO2 and 75% of the H2S extracted.

In this study we analyze seismicity data as reported by the Icelandic Meteorological Office Regional network, (1991-present) and the ON Power/ISOR local network (2016-present) and compare with operational parameters.  We show 1) how the seismicity responds to changes in flow, pressure and temperature of the injected fluid, 2) how individual wells seem to respond differently, 3) how the mitigation measures taken by the operator have worked and 4) look for changes in seismicity due to the CO2 sequestration.

This work has been funded by the European Union’s Horizon 2020 research and innovation Program projects Carbfix2 (grant agreement number 764760) and S4CE (grant agreement number 764810).

How to cite: Hjörleifsdóttir, V., Gunnarsson, G., Kristjánsdóttir, S., Sigfússon, B., Geirsson, H., Jónsdóttir, K., Gunnarsson, I., and Ágústsson, K.: Induced earthquakes at the carbon sequestration site Carbfix2, Hellisheiði, Iceland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19749, https://doi.org/10.5194/egusphere-egu2020-19749, 2020.

EGU2020-20317 | Displays | ERE6.2

Analysis of the seismic response to reservoir development and long-term operation at the Rittershoffen deep geothermal site

Rike Köpke, Olivier Lengliné, Jean Schmittbuhl, Emmanuel Gaucher, and Thomas Kohl

In a geothermal reservoir, seismicity may be induced due to changes in the subsurface as a result of drilling, stimulation or circulation operations. The induced seismic events are therefore strongly linked to the fluid flow, the mechanical state of the reservoir and the geological structures that impact the stress field and make this fluid flow possible. Here, the study is based on the monitoring of the development and operation of the deep geothermal site at Rittershoffen (Alsace, France) using different seismic networks covering various operational periods from September 2012 to present, including the drilling of the well doublet GRT1/GRT2, stimulation of GRT1 and well testing. The seismicity induced by these operations has the potential to give valuable insight into the geomechanical behaviour of the reservoir and the geometry of the fracture network. The present study gives an overview of the spatial and temporal development of the induced seismicity and the magnitudes of the events to provide insights into active structures in the reservoir.

 

To improve the level of detection, we first apply a template matching algorithm to the continuous waveforms recorded by the seismic networks. After running the detection with the template matching, the relative locations of all detected events are calculated as well as relative magnitudes. This workflow is applied to the whole time period from the start of the drilling in 2012 up to 2017. The spatial and temporal evolution of the events and their magnitudes shows how the different operations during reservoir development influence the seismogenic development of the reservoir and the seismic activity during continuous operation of the site. Further analysis like b-value computation, estimation of the best-fitting planes to the seismic clouds and evaluation of the waveform correlation between the seismic events give insight into the processes that induced the seismicity and the relation between different seismic intervals.

 

Focus of the present study is on the similarities and differences in the seismic response of the reservoir to the three subsequent stimulations of GRT1, called thermal, chemical and hydraulic stimulation. Results show that the seismicity induced during the hydraulic stimulation is much stronger in terms of seismicity rate and magnitudes than seismicity induced during thermal stimulation and migrates further into the reservoir. Noticeably, after a seismically quiet period of four days after the hydraulic stimulation a short burst of seismicity occurred unrelated to any operations on site. Seismicity during this delayed interval proved to have quite distinct characteristics from the seismicity induced during injection. While no significant seismicity was induced during chemical stimulation, the operation may have had an important influence on the seismic response of the reservoir during hydraulic stimulation by changing the state of the present fracture network.

How to cite: Köpke, R., Lengliné, O., Schmittbuhl, J., Gaucher, E., and Kohl, T.: Analysis of the seismic response to reservoir development and long-term operation at the Rittershoffen deep geothermal site, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20317, https://doi.org/10.5194/egusphere-egu2020-20317, 2020.

Locating and characterizing the seismicity in a reservoir is crucial for any geothermal project. This study is the first time that the seismicity in a geothermal reservoir is characterized using time-reverse imaging (TRI). The spatio-temporal distribution of events in combination with focal mechanism solutions may enable the mapping of existing fault networks, the estimation of local stress regimes and the distinction between tectonic and induced events. Combining these results with results from other methodologies will in the future lead to an informed understanding of the physical processes occurring in reservoirs.

TRI is a method for locating and characterizing seismic events. TRI uses the whole time-reversed waveform and a seismic wave propagation solver to locate and characterize events. Therefore, it does not rely on the identification of seismic events and their onsets in the traces. In contrast to common tools that provide hypocenters and focal mechanism solutions for seismic events, TRI does not assume any a priori knowledge about the sources. Since events are not picked in the seismic traces, no assumption is made about the number of sources recorded in a certain time window. Similarly, the characterization of events does not exclude any source type or put any constraints or assumptions on the sources, such as them being only of double-couple nature. Therefore, TRI may be especially well-suited when the overall type of sources is not known or if it is suspected that common localization and characterization tools are not adequately depicting the physical processes in the subsurface.

In the first part of this study, seismic events, that occurred in the geothermal field of Los Humeros in Mexico, are located using TRI. So-called sensitivity maps are used to enhance the localization capabilities and to determine the spatial variation in source-location accuracy. In the second part of this study, the located events are characterized by determining the full time-dependent moment tensor. Since no assumption about the source type is made, these moment tensors complement results obtained from more standardized tools.

How to cite: Finger, C. and Saenger, E. H.: Locating and characterizing seismic events in Los Humeros (Mexico) using time-reverse imaging, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13116, https://doi.org/10.5194/egusphere-egu2020-13116, 2020.

EGU2020-3392 | Displays | ERE6.2

Seismic moment evolution during hydraulic stimulations in EGS projects

Georg Dresen, Stephan Bentz, Grzegorz Kwiatek, Patricia Martinez-Garzon, and Marco Bohnhoff

Recent results from an EGS project in Finland suggest a possibly successful physics-based approach in controlling stimulation-induced seismicity in geothermal projects. We analyzed the temporal evolution of seismicity and the growth of maximum observed moment magnitudes for a range of past and present stimulation projects. Our results show that the majority of the stimulation campaigns investigated  reveal a clear linear relation between  injected fluid volume, hydraulic energy and cumulative seismic moments. For most projects studied, the observations are in good agreement with existing physical models that predict a relation between injected fluid volume and maximum seismic moment of induced events. This suggest that seismicity results from a stable, pressure-controlled rupture process at least for an extended injection period. Overall evolution of seismicity is independent of tectonic stress regime and is most likely governed by reservoir specific parameters, such as the preexisting structural inventory. In contrast, there are few stimulations that reveal unbound increase in seismic moment suggesting that for these cases evolution of seismicity is mainly controlled by stress field, the size of tectonic faults and fault connectivity. Transition between the two states may occur at any time during injection, or not at all. Monitoring and traffic-light systems used during stimulations need to account for the possibility of unstable rupture propagation from the very beginning of injection by observing the entire seismicity evolution in near-real-time and at high resolution for an immediate reaction in injection strategy.

How to cite: Dresen, G., Bentz, S., Kwiatek, G., Martinez-Garzon, P., and Bohnhoff, M.: Seismic moment evolution during hydraulic stimulations in EGS projects, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3392, https://doi.org/10.5194/egusphere-egu2020-3392, 2020.

EGU2020-18712 | Displays | ERE6.2 | Highlight

A triggered seismic swarm below the city of Strasbourg, France on Nov 2019

Jean Schmittbuhl, Olivier Lengliné, Sophie Lambotte, Marc Grunberg, Cécile Doubre, Jérôme Vergne, François Cornet, and Frédéric Masson

On Nov 12, 2019, a Ml3.1 earthquake was felt by the whole population of the city of Strasbourg, France. It was located by the BCSF-RéNaSS (EOST) in the northwestern part of the town (Robertsau area) at a depth of 5.5km. Its location in the vicinity of the deep geothermal wells (GEOVEN), the temporal correlation with the injection activity on site, the similarity of the depth between the bottom of the wells and  the hypocenter of the event, the lack of local seismicity before the event occurrence, the known geological structures including crustal faults in the area, immediately questioned the possible triggering of the event by the deep geothermal activities despite the relatively large distance (4-5km). In order to assess the origin of the Ml3.1 event, we report here on the data analysis performed from the seismological monitoring of the local area using the catalog produced by BCSF-RéNaSS and the regional public seismic networks. The main result is that the event is part of a remote triggered swarm that was initiated at least six days before the main shock and lasted more than two months. Template matching has been applied and allowed for a significant improvement of the detections. Double-difference relocations evidenced a set of conjugated faults in the swarm area that extends over 800m. Focal mechanisms of the two main events are very consistent with the known regional fault in the area. The regional stress field in combination with the fault orientation and a Coulomb failure criterion shows that the swarm location is in an unstable domain if the cohesion of the fault is weak, particularly sensitive to stress perturbations.

How to cite: Schmittbuhl, J., Lengliné, O., Lambotte, S., Grunberg, M., Doubre, C., Vergne, J., Cornet, F., and Masson, F.: A triggered seismic swarm below the city of Strasbourg, France on Nov 2019, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18712, https://doi.org/10.5194/egusphere-egu2020-18712, 2020.

EGU2020-8228 | Displays | ERE6.2

Imaging of active faults from the temporal and spatial distributions of relocated seismicity induced beneath an EGS site in the Pohang region of southeastern Korea

Jer-Ming Chiu, Kwanghee Kim, Shu-Chioung Chiu, Suyoung Kang, Wooseok Seo, and Jongwon Han

The 2017 Pohang earthquake (ML 5.4) is the second largest earthquake occurred in an intraplate in modern Korea and is considered the largest induced earthquake from an EGS system around the world.  The mainshock was proceeded by a few foreshocks and followed by a few thousands of aftershocks.  Numerous densely distributed seismic stations in local and regional distances were deployed to monitor this earthquake sequence.  Original hypocenters in the Pohang region were located using HYPODD that is independent on crustal structures.  A comprehensive crustal Vp and Vs model was recently available from an invited committee of foreign experts based on well logs and regional seismic data.  This model is then revised, especially the uppermost few hundred meters, based on results from a study of S to P converted waves from shallow interfaces beneath various stations, from the traditional Wadati plots analysis, and from the interpretation of two short seismic reflection/refraction profiles.  From continuous data, 5 to 10 folds of additional earthquakes than the original manually picked events can be identified and located. P and S arrival times from all earthquakes are re-picked from continuous data and are relocated using the revised model and Hypoellipse program.  Temporal and spatial distribution of relocated seismicity at depths range from 3 to 7 km are more clustered and confined than that from the original catalog.  A few thin vertical cross-sectional views of hypocenters parallel and perpendicular to the seismicity reveal that seismicity propagates along multiple NE-SW trending faults beneath the Pohang basin and extending NE offshore into East Sea.  These fault system is sandwiched between the Yongshan fault and a few other secondary faults to the south.  The main shock (5.4) and the two largest aftershocks (4.3 and 4.6) as well as their associated aftershocks show predominantly NE-SW strike-slip with reverse faulting propagating along three different adjacent faults.  Geometry of active faults and their tectonic implications will be presented and discussed in the meeting.

How to cite: Chiu, J.-M., Kim, K., Chiu, S.-C., Kang, S., Seo, W., and Han, J.: Imaging of active faults from the temporal and spatial distributions of relocated seismicity induced beneath an EGS site in the Pohang region of southeastern Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8228, https://doi.org/10.5194/egusphere-egu2020-8228, 2020.

EGU2020-12978 | Displays | ERE6.2

The fault that moved during the 2017 Mw 5.4 Pohang earthquake in SE Korea; implications for the EGS project and the generation of the Pohang earthquake

Toshihiko Shimamoto, Shengli Ma, Lu Yao, Tetsuhiro Togo, HyunJee Lim, and Moon Son

EGU2020-18960 | Displays | ERE6.2

Modeling of the Pohang Earthquake Probability Using the Seismogenic Index

Serge Shapiro and Jin-Han Ree

A strong earthquake of Mw5.5 occurred on 15 November 2017, shortly after finishing borehole fluid injections performed for the geothermal development of the Pohang Enhanced Geothermal System. With a high probability, the earthquake was triggered by these operations. In this work we consider the Pohang Earthquake in the frame of the Seismogenic Index Model. We attempt to estimate the triggering probability of this event as well as a general  probability of triggering of arbitrary-magnitude earthquakes at the Pohang site before and after the termination of the fluid injections. A fluid injection in a point of an infinite continuum is taken here as a prototype of the Pohang situation.

The seismogenic index of the Pohang site is approximately between -2 and -1. During the injection operations, one can observe  a tendency of the
seismogenic index to increase with time. This was possibly  an indication of a gradual involvement of seismically more active zones in the stimulated domain. Especially alarming was the event of Mw3.3 on April 15th of 2017. Probably, this event indicated a jump of the seismogenic index to -1. All injection operations in both boreholes should be stopped after this event.

Our estimate of the probability of the Pohang earthquake is approximately 15%. One of  decisive factors for  this relatively high probability was the low b value. A combination of a low b-value and a rather high seismogenic index made the probability of a hazardous event significant. A termination of all injection operations after the occurrence of the event of M_w3.3 would significantly reduce the probability of an M_w5.5 event down to approximately 3%. An injection termination at M_w2.3 would reduce it down to approximately 1%.

The Pohang earthquake has a clear character of a triggered event. A real-time well developed seismic observation system permitting a precise 3-D event location and a monitoring of the temporal evolution of the geometry of the stimulated volume and of the seismogenic index could potentially help to prevent or to delay the occurrence of such an  earthquake.

This paper provides a simplified consideration based on analytical formulations for an effective homogeneous porous medium and monotonic injection operations. Numerical simulations of more realistic injection configurations,  an analysis of modeling results along the indicated here directions, further enhanced processing and analysis of seismologic records are required for more detailed understanding of processes led to the Pohang event. 

How to cite: Shapiro, S. and Ree, J.-H.: Modeling of the Pohang Earthquake Probability Using the Seismogenic Index , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18960, https://doi.org/10.5194/egusphere-egu2020-18960, 2020.

It has been long understood that the injection of fluids into the subsurface, a common practice in several industries, often leads to seismic activity by altering the fluid pressures and stress states acting along fault structures. In some cases, this puts the people and infrastructure located nearby at considerable risk. The effective mitigation of this potential hazard relies heavily on understanding the physical mechanisms controlling the behavior of injection-induced seismicity. Here, we aim to better understand the spatiotemporal patterns of the seismicity through the concept of triggering fronts (i.e. the propagating front where the onset of seismicity occurs). Previously, triggering fronts have been studied mostly in the context of homogenous porous media. Here, field scale simulations of fluid injection into fractured rock are modeled as linear, uncoupled fluid flow. While injection-induced seismicity is certainly affected by poroelastic stressing and nonlinear hydraulic parameters of the rock, the focus of this study is to understand the impact of a discrete fracture network on patterns of seismicity. Therefore, poroelastic and nonlinear effects are ignored. Results indicate that the pathways of high permeability within the fracture network greatly influence the migration of the triggering front. While the triggering front clearly follows a diffusive process as expected, the corresponding diffusivity is found to be distinct from the effective hydraulic diffusivity of the domain. We, therefore, call this diffusivity the seismic diffusivity of the fractured rock. Understanding seismic diffusivity may help us better interpret datasets of injection-induced seismicity and potentially forecast the patterns of injection-induced seismicity in well-characterized formations.

How to cite: Haagenson, R. and Rajaram, H.: Seismic diffusivity: The influence of fracture networks on the patterns of induced seismicity., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20308, https://doi.org/10.5194/egusphere-egu2020-20308, 2020.

Seismic hazard due to fluid invasion in hydraulic fracturing, wastewater disposal, and enhanced geothermal systems has become a concern for industry and nearby residents. One of the challenges associated with this seismic hazard is the estimation of the spatial effects of these industry operations. Based on a large set of real-world fluid-induced seismicity catalogs, it was recently found that the spatial decay of seismic activity with distance from injection wells exhibits two typical behaviors: short-range decay and long-range decay. The distinction between the two groups can be captured by the exponent in the seismicity density but the underlying origin remains unknown. Here, we introduce a novel conceptual model that not only can capture the observed frequency magnitude distribution of fluid-induced seismic events but also explains different spatial decay exponents observed. In particular, previous models of fluid-induced seismicity have assumed that the permeability and porosity field is either uniform or random and spatially uncorrelated. However, power-law scaling in the spatial frequency power spectrum of well-logs, S(k)∝1/k^β, has been observed for many different physical properties of rocks such as sonic velocity, porosity, and log(permeability). Our model takes advantage of this by introducing a spatially correlated field for porosity and permeability. Our analysis shows that increasing β can decrease the spatial decay exponent, leading to more seismic activity at larger distances from the injection site. In particular, our model explains the two different types of behavior in the spatial distribution of fluid-induced microseismic events as a consequence of different correlations in permeability.

How to cite: Khajehdehi, O., Karimi, K., and Davidsen, J.: The effect of correlated permeability on spatiotemporal distribution of microseismic events in a conceptual model of fluid-induced seismicity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5826, https://doi.org/10.5194/egusphere-egu2020-5826, 2020.

We consider seismogenic asperities loaded by aseismic slip on a fault, which is induced by fluid circulation, as a simple example of fault reactivation. For this purpose, we combine two methods. The TOUGH2 (Transport Of Unsaturated Ground water and Heat) code is used for modeling the pore pressure evolution within a fault and then a Boundary Integral Equation Method (BIEM) is applied for simulating fault slip, including aseismic slip on the entire fault plane and fast slip on seismogenic asperities. The fault permeability is assumed stress-dependent and therefore is not constant but varies during a simulation. We adopt the Coulomb friction and a cyclic slip-strengthening-then-weakening friction model governing the fault slip, which allows for repeated asperity slip. We were able to demonstrate the entire process from the fluid injection, pore pressure increase, aseismic slip to seismogenic asperity slip. We tested a step-like increase of injection rate with time, which is common for hydraulic fracturing and reservoir stimulation at deep geothermal sites. Under this configuration, the pore pressure increase is not proportional to the injection rate, as the permeability depends on the stress.  Fault slip on seismogenic asperities is triggered repeatedly by surrounding aseismic slip. We find, in a given example, that the reccurence of the fast slip on asperity is approximatively proportional to the injected fluid volume, inferring that the aseismic slip amount increases proporitionally to the fluid volume as well.

How to cite: Aochi, H. and Rutqvist, J.: Hydro-mechanical modeling of seismogenic asperity loaded by aseismic slip through TOUGH-BIEM simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6643, https://doi.org/10.5194/egusphere-egu2020-6643, 2020.

EGU2020-13568 | Displays | ERE6.2

Induced seismicity associated with fluid injection into a fractured rock mass

Brice Lecampion, Federico Ciardo, Alexis Saèz Uribe, and Andreas Möri

We investigate via numerical modeling the growth of an aseismic rupture and the possible nucleation of a dynamic rupture driven by fluid injection into a fractured rock mass. We restrict to the case of highly transmissive fractures compared to the rock matrix at the scale of the injection duration and thus assume an impermeable matrix. We present a new 2D hydro-mechanical solver allowing to treat a large number of pre-existing frictional discontinuities. The quasi-static (or quasi-dynamic) balance of momentum is discretized using boundary elements while fluid flow inside the fracture is discretized via finite volume. A fully implicit scheme is used for time integration. Combining a hierarchical matrix approximation of the original boundary element matrix with a specifically developed block pre-conditioner enable a robust and efficient solution of large problems (with up to 106 unknowns). In order to treat accurately fractures intersections, we use piece-wise linear displacement discontinuities element for elasticity and a vertex centered finite volume method for flow.

We first consider the case of a randomly oriented discrete fracture network (DFN) having friction neutral properties. We discuss the very different behavior associated with marginally pressurized versus critically stressed conditions. As an extension of the case of a planar fault (Bhattacharya and Viesca, Science, 2019), the injection into a DFN problem is governed by the distribution (directly associated with fracture orientation) of a dimensionless parameter combining the local stress criticality (function of the in-situ principal effective stress, friction coefficient and local fracture orientation) and the normalized injection over-pressure. The percolation threshold of the DFN which characterizes the hydraulic connectivity of the network plays an additional role in fluid driven shear cracks growth. Our numerical simulations show that a critically stressed DFN exhibits fast aseismic slip growth (much faster than the fluid pore-pressure disturbance front propagation) regardless of the DFN percolation threshold. This is because the slipping patch growth is driven by the cascades of shear activation due to stress interactions as fractures get activated. On the other hand, the scenario is different for marginally pressurized / weakly critically stressed DFN. The aseismic slip propagation is then tracking pore pressure diffusion inside the DFN. As a result, the DFN percolation threshold plays an important role with low percolation leading to fluid localization and thus restricted aseismic rupture growth.

We then discuss the case of fluid injection into a fault damage zone. Using a linear frictional weakening model for the fault, we investigate the scenario of the nucleation of a dynamic rupture occurring after the end of the injection (as observed in several instances in the field). We delimit the injection and in-situ conditions supporting such a possibility.

How to cite: Lecampion, B., Ciardo, F., Saèz Uribe, A., and Möri, A.: Induced seismicity associated with fluid injection into a fractured rock mass, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13568, https://doi.org/10.5194/egusphere-egu2020-13568, 2020.

Predicting reservoir compaction resulting from fluid depletion is important to assess potential hazards and risks associated with fluid production, such as surface subsidence and induced seismicity. Globally, many producing oil and gas fields are experiencing these phenomena. The giant Dutch Groningen gas field, the Netherlands, is currently measuring up to 35 cm of surface subsidence and experiencing widespread induced seismicity. To accurately predict reservoir compaction, reservoir-scale models incorporating realistic grain-scale microphysical processes are needed. As a first step towards that aim, Discrete Element Method (DEM) modeling can be used to predict the compaction behavior of granular materials at the cm/dm-scale, under a wide range of conditions representing realistic in-situ stress and pressure conditions.

Laboratory experiments on the reservoir of the Groningen gas field, the Slochteren sandstone, have shown elastic deformation, inelastic deformation due to clay film consolidation, and inelastic deformation due to grain sliding and grain failure. Since the available contact models for DEM modeling do not yet incorporate all of these grain-scale processes, a new contact model, the Slochteren sandstone contact model (SSCM), was developed to explicitly take these mechanisms into account and integrate them into Particle Flow Code (PFC), which is a powerful DEM approach.

In SSCM the blunt conical contact with an apex angle close to 180˚ is assumed to properly model the elastic behavior, as well as the grain failure mechanism. Compacting an assembly of particles with this type of contact model, results in a range of contact shapes, from point to long contacts, which is compatible with microstructural observations of Slochteren sandstone.  The deformation of thin intergranular clay coatings is implemented following the microphysical model proposed by Pijnenburg et al. (2019a).

The model allows for the systematic investigation of porosity, grain size distribution and intergranular clay film content on compaction behavior. The model was calibrated against a limited number of hydrostatic and deviatoric stress experiments (Pijnenburg et al. 2019b) and verified against an independent set of uniaxial compressive experiments (Hol et al. 2018) with a range of porosities, grain size distributions and clay content. The calibrated model was also used to make predictions of the compaction behavior of Slochteren sandstone. These predictions were compared to field measurements of in-situ compaction and showed an acceptable match if the uncertainties of field measurements are considered in calculations.

References:

Pijnenburg, R.P.J., Verberne, B.A., Hangx, S.J.T. and Spiers, C.J., 2019. Intergranular clay films control inelastic deformation in the Groningen gas reservoir: Evidence from split‐cylinder deformation tests. Journal of Geophysical Research: Solid Earth.

Pijnenburg, R.P.J., Verberne, B.A., Hangx, S.J.T. and Spiers, C.J., 2019. Inelastic deformation of the Slochteren sandstone: Stress‐strain relations and implications for induced seismicity in the Groningen gas field. Journal of Geophysical Research: Solid Earth.

Hol, S., van der Linden, A., Bierman, S., Marcelis, F. and Makurat, A., 2018. Rock physical controls on production-induced compaction in the Groningen Field. Scientific reports, 8(1), p.7156.

How to cite: Mehranpour, M. H., Hangx, S. J. T., and Spiers, C. J.: Discrete Element Method modelling of Groningen reservoir compaction using a new contact model describing elastic and inelastic grain-scale interactions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13941, https://doi.org/10.5194/egusphere-egu2020-13941, 2020.

EGU2020-10680 | Displays | ERE6.2

Exploring possible causative mechanisms for earthquakes triggered by hydraulic fracturing: examples from the Montney Basin, BC, Canada.

Alessandro Verdecchia, Bei Wang, Yajing Liu, Rebecca Harrington, Marco Roth, Andres Peña Castro, and John Onwuemeka

The Dawson-Septimus area near the towns of Dawson Creek and Fort St. John, British Columbia, Canada has experienced a drastic increase in seismicity in the last ~ 6 years, from no earthquakes reported by Natural Resources Canada (NRCan) prior to 2013 to a total of ~ 200 cataloged events in 2013 – 2019. The increase follows the extensive horizontal drilling and multistage hydraulic fracturing activity that started to extract shale gas from the unconventional siltstone resource of the Montney Formation. In addition to hydraulic fracturing, ongoing wastewater disposal in the permeable sandstones and carbonates located stratigraphically above and below the Montney formation may also be contributing to elevated seismicity in the region. Earthquakes occur in close spatial and temporal proximity to hydraulic fracturing wells, at distances up to ~ 10 km. The expected diffusion time scales in the low-diffusivity siltstone rock units and the temporal and spatial scale of seismic activity beg questions about the possible processes controlling the location and timing of earthquakes.

 

Here, we investigate the causative mechanisms for two of the largest events in the Montney Basin, British Columbia: the August 2015 M4.6 earthquake near Fort St. John, and the November 2018 M4.5 earthquake near Dawson Creek. Both events are thought to have occurred within the crystalline basement, ~2 km below the injected shale units (Montney formation).  We use a finite-element 3D poroelastic model to calculate the coupled evolution of elastic stress and pore pressure due to injection at several hydraulic fracturing stages. Initially, we consider a simple layered model with differing hydraulic parameters based on lithology. Subsequently, also considering the seismicity distribution for each sequence, we introduce hypothetic hydraulic conduits connecting the injection intervals with the crystalline basement, where the respective mainshock occurred. We test a range of permeability values (10-15 m2– 10-12 m2) commonly implemented for fault zones.

 

Our results show that, for both cases, the poroelastic stress perturbation may be not sufficient to trigger events in the basement. Instead, a scenario with a high-permeability (10-13 m2– 10-12 m2) conduits connecting the Montney formation to the fault responsible for the mainshock could better explain the relationship between the hydraulic stimulation and the timing of the two M > 4 earthquakes. For the 2018 M4.5 event, aftershock distribution can be mainly attributed to earthquake-earthquake interaction via static Coulomb stress transfer from the mainshock slip. In addition to the modeling of single well/event sequences, future work will include the long-term poroelastic effect due to multiple disposal wells located in the region.

How to cite: Verdecchia, A., Wang, B., Liu, Y., Harrington, R., Roth, M., Peña Castro, A., and Onwuemeka, J.: Exploring possible causative mechanisms for earthquakes triggered by hydraulic fracturing: examples from the Montney Basin, BC, Canada., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10680, https://doi.org/10.5194/egusphere-egu2020-10680, 2020.

EGU2020-6369 | Displays | ERE6.2

Coupling poroelastic stress change and rate-state fault slip models to simulate fluid injection induced seismic and aseismic slip

Yajing Liu, Alessandro Verdecchia, Kai Deng, and Rebecca Harrington

Fluid injection in unconventional hydrocarbon resource exploration can introduce poroelastic stress and pore pressure changes, which in some cases may lead to aseismic slip on pre-existing fractures or faults. All three processes have been proposed as candidates for inducing earthquakes up to 10s of kilometers from injection wells. In this study, we examine their relative roles in triggering fault slip under both wastewater disposal and hydraulic fracturing scenarios. We first present modeling results of poroelastic stress changes on a previously unmapped fault near Cushing, Oklahoma, due to injection at multiple wastewater disposal wells within ~ 10 km of distance, where over 100 small to moderate earthquakes were reported between 2015/09 to 2016/11 including a Mw5.0 event at the end of the sequence. Despite the much larger amplitude of pore pressure change, we find that earthquake hypocenters are well correlated with positive shear stress change, which dominates the regimes of positive Coulomb stress change encouraging failure. Depending on the relative location of the disposal well to the recipient fault and its sense of motion, fluid injection can introduce either positive or negative Coulomb stress changes, therefore promoting or inhibiting seismicity. Our results suggest that interaction between multiple injection wells needs to be considered in induced seismicity hazard assessment, particularly for areas of dense well distributions. Next, we plan to apply the model to simulate poroelastic stress changes due to multi-stage hydraulic fracturing wells near Dawson Creek, British Columbia, where a dense local broadband seismic array has been in operation since 2016. We will investigate the relative amplitudes, time scales, and spatial ranges of pore pressure versus solid matrix stress changes in influencing local seismicity.

Finally, we have developed a rate-state friction framework for calculating slip on a pre-existing fault under stress perturbations for both the disposal and hydraulic fracturing cases. Preliminary fault slip simulation results suggest that fault response (aseismic versus seismic) highly depends on 1) the relative timing in the intrinsic earthquake cycle (under tectonic loading) when the stress perturbation is introduced, 2) the amplitude of the perturbation relative to the background fault stress state, and 3) the duration of the perturbation relative to the “memory” timescale governed by the rate-state properties of the fault. Our modeling results suggest the design of injection parameters could be critical for preventing the onset of seismic slip.

How to cite: Liu, Y., Verdecchia, A., Deng, K., and Harrington, R.: Coupling poroelastic stress change and rate-state fault slip models to simulate fluid injection induced seismic and aseismic slip, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6369, https://doi.org/10.5194/egusphere-egu2020-6369, 2020.

EGU2020-18774 | Displays | ERE6.2

The influence of the heterogeneous asperity distribution on induced seismicity and permeability evolution during hydraulic fault zone stimulation

Linus Villiger, Dominik Zbinden, Antonio Pio Rinaldi, Paul Antony Selvadurai, Hannes Krietsch, Valentin Gischig, Joseph Doetsch, Mohammadreza Jalali, Florian Amann, and Stefan Wiemer

Several decameter-scale in-situ stimulation experiments were conducted in crystalline rock at the Grimsel Test Site, Switzerland, with the aim to advance our understanding of the seismo-hydro-mechanical processes associated with deep geothermal reservoir stimulation. To allow comparability between the experiments, a standardized injection protocol was applied for all experiments. Induced seismicity was recorded using acoustic emission sensors and accelerometers, which were distributed along tunnel walls and within four boreholes. Hydro-mechanical responses of the fault zones were measured using grouted longitudinal fiberoptic strain sensors and open pressure monitoring borehole intervals. A total of four ductile shear zones (with brittle overprint) and two brittle-ductile shear zones have been stimulated during these experiments.

Here we present an analysis of heterogeneous permeability evolution within a target shear zone during ongoing stimulation. The shear zone in question is an originally ductile shear zone which contains a single fracture in the injection interval. The observed planar seismicity cloud indicates that most of the stimulation process was confined within the target shear zone. Hydraulic characterization of the injection interval before and after stimulation revealed an enhancement in interval transmissivity from 8.3-10-11 m2/s to 1.5-7 m2/s. Within the reservoir, the seismo-hydro-mechanical data (i.e. seismicity cloud, pressure peaks and local deformation) spatiotemporally coincide, suggesting that permeability enhancement along the shear zone is highly localized and heterogeneous. Thus, we argue that the permeability evolution is linked to asperity distribution and breakdown within the shear zone.

The conceptual model developed from the experimental analysis is implemented in a three-dimensional numerical model, with which we attempt to simulate the directional permeability creation observed in the experiment. The model accounts for a discrete planar fault zone of finite thickness with distributed low-permeability, brittle asperities embedded in a more permeable damage zone mimicking the ductile shear zone at Grimsel. The hydro-mechanical processes are modeled with the TOUGH-FLAC simulator, which sequentially couples fluid flow and poroelastic deformation within the fault and the surrounding medium. A Mohr-Coulomb failure criterion is used to simulate asperity reactivation, which can lead to permeability enhancement of the reactivated area.

How to cite: Villiger, L., Zbinden, D., Rinaldi, A. P., Selvadurai, P. A., Krietsch, H., Gischig, V., Doetsch, J., Jalali, M., Amann, F., and Wiemer, S.: The influence of the heterogeneous asperity distribution on induced seismicity and permeability evolution during hydraulic fault zone stimulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18774, https://doi.org/10.5194/egusphere-egu2020-18774, 2020.

Industrial projects that involve fluid injection into the deep underground (e.g., geothermal energy, wastewater disposal) can induce seismicity, which may jeopardize the acceptance of such geo-energy projects and, in the case of larger induced earthquakes, damage infrastructure and pose a threat to the population. Such earthquakes can occur because fluid injection yields pressure and stress changes in the subsurface, which can reactivate pre-existing faults. Many studies have so far focused on injection into undisturbed reservoir conditions (i.e., hydrostatic pressure and single-phase flow), while only very few studies consider disturbed in-situ conditions including multi-phase fluid flow (i.e., gas and water). Gas flow has been suggested as a trigger mechanism of aftershocks in natural seismic sequences and can play an important role at volcanic sites. In addition, the deep geothermal project in St. Gallen, Switzerland, is a unique case study where an induced seismic sequence occurred almost simultaneously with a gas kick, suggesting that the gas may have affected the induced seismicity.

Here, we focus on the hydro-mechanical modeling of fluid injection into disturbed reservoir conditions considering multi-phase fluid flow. We couple the fluid flow simulator TOUGH2 with different geomechanical codes to study the effect of gas on induced seismicity in general and in the case of St. Gallen. The results show that overpressurized gas can affect the size and timing of induced earthquakes and that it may have contributed to enhance the induced seismicity in St. Gallen. Our findings can lead to a more detailed understanding of the influence of a gas phase on the induced seismicity.

How to cite: Zbinden, D., Rinaldi, A. P., Diehl, T., and Wiemer, S.: Multi-phase hydromechanical modeling of induced seismicity: general insights and the case study of the deep geothermal project in St. Gallen, Switzerland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21428, https://doi.org/10.5194/egusphere-egu2020-21428, 2020.

EGU2020-10907 | Displays | ERE6.2

Geomechanical modelling of spent fluid reinjection in the Hengill geothermal field

Vanille A. Ritz, Antonio P. Rinaldi, Elisa Colas, Raymi Castilla, Peter M. Meier, and Stefan Wiemer

Monitoring micro-seismicity during operations of a geothermal field is critical to the understanding of seismic hazard and changes in the reservoir. In the context of a geothermal project, induced earthquakes are an important tool to enhance the permeability and thus productivity of reservoirs and to image structure and processes. However, felt and/or damaging earthquakes are a major threat to societal acceptance and regulatory license to operate. With the adaptive data-driven tool ATLS (Adaptive Traffic Light System), we aim at managing and mitigating the risk posed by induced earthquakes during stimulation and operations, while at the same time ensuring and optimising the productivity.

The demonstration site for the application of ATLS lies in the Hengill volcanic region located in the South-West of Iceland, host to two power plants (Hellisheiði and Nesjavellir) with a total production capacity of 423 MWe and 433MWth. The production of energy and heat is accompanied by reinjection of the spent geothermal water in dedicated areas, both to maintain production and to comply with legal requirements. These reinjection areas have been showing different seismic responses to drilling and injection operations. We investigate these different behaviours by performing numerical modelling for two of the reinjection regions.

Two models are compared: TOUGH2-Seed, a full 3-dimensional stochastic simulator and an analytical model based on a cumulative density function linking maximum pressure in the reservoir and reactivation. Those two models fulfil two different aspects of the development of an ATLS, with the full 3D allowing an in-depth dive in the driving mechanisms of induced seismicity; and the analytical solution providing a robust and fast approximation of the forecast for real-time application. We show that both models can reproduce observed seismicity patterns in the Hengill geothermal field.

How to cite: Ritz, V. A., Rinaldi, A. P., Colas, E., Castilla, R., Meier, P. M., and Wiemer, S.: Geomechanical modelling of spent fluid reinjection in the Hengill geothermal field, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10907, https://doi.org/10.5194/egusphere-egu2020-10907, 2020.

EGU2020-5245 | Displays | ERE6.2

Large-Scale Migration Patterns of Wastewater-Induced Earthquakes in the Central U.S.

Lisa Johann and Serge A. Shapiro

It is understood that the recent acceleration of seismic event occurrences in Kansas and Oklahoma, U.S., can be connected to the large-volume disposal of wastewater. These highly saline fluids are co-produced with oil and gas and are re-injected under gravity into the highly porous Arbuckle aquifer. Since 2015, injection rates have been decreasing. However, the seismic hazard in that region remains elevated. Furthermore, it has been noticed that some events in Kansas occur far from disposal wells.

To analyse spatio-temporal patterns between the fluid injection and earthquake locations, we applied a time-dependent 2D cross-correlation technique. This reveals a vectorial migration pattern of the seismic events. Whereas early events occur towards the east-sourtheast, later events are located preferably in northeastern direction of large volume injectors. With time, event locations migrate further in that direction. We explain this observation as well as measured Arbuckle pore pressures by a directional pore-fluid pressure diffusion and poroelastic stress propagation. This also follows from our principal two-dimension poroelastic finite element model which is of predictive power and identifies controlling parameters of the observations. These are mainly the permeability of the target injection formation and the seismogenic basement as well as the anisotropic permeability and the critical fault strength distribution. Our results lead to the conclusion that remote locations are destabilised also when injection rates are declining.

Thus, volume reductions may only provide a direct effect to lower earthquake rates locally. However, a state-wide decrease of the seismicity may require longer times such that the seismic hazard due to wastewater disposal induced seismicity may remain for decades. 

How to cite: Johann, L. and Shapiro, S. A.: Large-Scale Migration Patterns of Wastewater-Induced Earthquakes in the Central U.S., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5245, https://doi.org/10.5194/egusphere-egu2020-5245, 2020.

EGU2020-16283 | Displays | ERE6.2

Cooling effects on induced seismicity in supercritical geothermal systems

Francesco Parisio, Victor Vilarrasa, Wenqing Wang, Olaf Kolditz, and Thomas Nagel

Geothermal energy is a fundamental piece of the puzzle in the carbon-free energy transition necessary to mitigate adverse effects of climate change. In this context, so-called supercritical geothermal systems (where resident brine is above its critical point) can reach a power output of up to 50 MW per-well and are becoming a reality thanks to the research effort of the international community. Supercritical systems are inherently complex because of fluid and solid rheology and because of the non-linear couplings involved between pore pressure, temperature and deformation in the porous and fractured rock. In this contribution, we have performed finite element analyses of coupled thermo-hydro-mechanical (THM) conditions in a supercritical geothermal system. The formulation employed includes a porosity-dependent permeability relationship that is derived through mass balance equations of the solid skeleton. The equations of state of water are based on IAPWS standards and span the whole range of temperature and pressure of interest in supercritical geothermal systems. We have analyzed an injection-production doublet scenario at 5.5 km depth, where the two wells are spaced 500 m apart and a major fault lies between them. When injecting in isothermal conditions, because of water mobility of the supercritical phase is higher than the liquid phase, minor perturbations are observed in the major fault. Seismicity increases rapidly following a pressure-diffusion response and only micro-seismicity is expected as the stress in the major fault shows minor changes. On the contrary, cold fluid injection generates large thermal-induced stress changes that diffuse following advective heat transport laws. Micro-seismicity is quickly triggered and, within 10 years in the current setting, the perturbation reaches the 250 m distant fault, where larger magnitude events are possible. Our findings bear important consequences in terms of safety of supercritical geothermal systems and proved that seismic response in amplified by re-injection-induced cooling.

How to cite: Parisio, F., Vilarrasa, V., Wang, W., Kolditz, O., and Nagel, T.: Cooling effects on induced seismicity in supercritical geothermal systems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16283, https://doi.org/10.5194/egusphere-egu2020-16283, 2020.

EGU2020-12863 | Displays | ERE6.2

The role of fault offset in induced seismicity potential

Victor Vilarrasa, Francesco Parisio, Roman Makhnenko, Haiqing Wu, and Iman Rahimzadeh Kivi

Geological media is envisioned as a strategic resource to store large volumes of CO2 and mitigate climate change. Geo-energy applications, such as geologic carbon storage, geothermal energy, and subsurface energy storage, involve injection and extraction of fluids that cause pressure diffusion. Pore pressure changes may induce seismicity, especially in faults that intersect the injection formation or are hydraulically connected with it. We numerically study with finite element analysis of coupled hydro-mechanical conditions how fault stability is affected by fluid injection into a porous aquifer that is overlaid and underlain by low permeability clay-rich formations. We model a layered sedimentary basin with alternating soft and low permeability with stiff and high permeability formations and include the crystalline basement at the bottom. Additionally, a low permeability steep fault, whose offset ranges from zero to the reservoir thickness, crosses the system. We consider a normal faulting stress regime typical of extensional environments. Simulation results show that the reservoir pressurization as a result of fluid injection causes significant stress changes around the fault that affect its stability. The stress changes depend on the stiffness of the rock juxtaposed to the pressurized reservoir. If there is no offset, the rock is stiff on both sides of the fault, inducing a homogeneous horizontal total stress increase along the thickness of the reservoir. As a result, the deviatoric stress becomes smaller and the induced seismicity potential is low. As the fault offset increases, some part of the base rock gets juxtaposed to the pressurized reservoir. The soft base rock deforms more than the reservoir rock in response to the reservoir expansion, inducing a lower horizontal total stress. Thus, fault stability reduces when the pressurized reservoir rock is juxtaposed with the softer base rock. This finding shows that the induced seismicity potential may increase with the fault offset.

How to cite: Vilarrasa, V., Parisio, F., Makhnenko, R., Wu, H., and Rahimzadeh Kivi, I.: The role of fault offset in induced seismicity potential, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12863, https://doi.org/10.5194/egusphere-egu2020-12863, 2020.

EGU2020-10514 | Displays | ERE6.2

Geomechanical Assessment of Potential for Induced Seismicity

Oliver Heidbach, Moritz Ziegler, and Sophia Morawietz

The Bavarian Molasse Basin is one of the largest European areas for low-enthalpy hydrothermal applications. In the last decades, more than 20 geothermal applications for district heating and even power generation have been established, and more are planned or under construction. At about one third of the projects, seismicity of up to Ml 2.4 has been observed after the onset of production and reinjection of fluids while no seismicity has been observed at the other project sites. In order to assess the potential for induced seismicity at a specific site, three parts of information are required: (1) The initial stress state, (2) the changes in the stress state due to production and reinjection, (3) a fault geometry (strike, dip), and (4) a fault properties in terms of a failure criterion. While a modelling of the production and/or injection induced stress changes is performed commonly and basic information on the failure behaviour of rocks is available, information on stress magnitudes is rare and unevenly distributed. Thus, 3D geomechanical-numerical modelling is used to estimate the stress state in a target area based on the few data records available.

We present a 3D geomechanical-numerical model of the initial stress state in the Bavarian Molasse Basin in order to assess the individual potential for induced seismicity at different geothermal sites. Our model area contains several lithological units with different rock properties. Additionally, in our approach, we quantify the uncertainties introduced by the variability of the 13 stress magnitude data records used for the calibration of the model. We further reduce the large uncertainties by introduction of additional observables that limit the range of acceptable stress states. From the model results, we extract the stress state and its uncertainties at the two geothermal sites Aschheim/Feldkirchen/Kirchheim and Poing that are in a distance of 4 km. While seismicity of up to Ml 2.1 has been observed in Poing, the other site remained seismically quiet. Our modelled stress state at the two sites in combination with according failure criteria on optimally oriented faults is in agreement with the seismological observations. Even considering uncertainties of 2σ, the modelled stress state in Aschheim/Feldkirchen/Kirchheim is stable, while in Poing even the average stress state is already critical. These results indicate the relevance of a geomechanical assessment of sites of subsurface applications in order to minimize the potential for induced seismicity.

How to cite: Heidbach, O., Ziegler, M., and Morawietz, S.: Geomechanical Assessment of Potential for Induced Seismicity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10514, https://doi.org/10.5194/egusphere-egu2020-10514, 2020.

EGU2020-8704 | Displays | ERE6.2

Analysis of microseismicity in the Hengill Geothermal Area, SW Iceland

Camilla Rossi, Francesco Grigoli, Simone Cesca, Sebastian Heimann, Paolo Gasperini, Vala Hjörleifsdóttir, Torsten Dahm, Christopher J. Bean, and Stefan Wiemer

Geothermal systems in the vicinity of the Hengill volcano, SW Iceland, started to be exploited for electrical power and heat production since the late 1960s, and today the two largest operating geothermal power plants are located at the Nesjavellir and the Hellisheidi. This area is a complex tectonic and geothermal site, being located at the triple junction between the Reykjanes Peninsula (RP), the Western Volcanic Zone (WVZ), and the South Iceland Seismic Zone (SISZ). The region is seismically highly active with several thousand earthquakes located yearly. The origin of such earthquakes may be either natural or anthropogenic. The analysis of microseismicity can provide useful information on natural active processes in tectonic, geothermal and volcanic environments as well as on physical mechanisms governing induced events. Here, we investigate the microseismicity occurring in Hengill area to understand physical source mechanisms and the origin of these microseismic events. We use a very dense broadband monitoring network deployed since November 2018 with support of the GEOTHERMICA project COSEISMIQ and apply robust and full-waveform based methods for earthquake location, clustering analysis and source mechanism determination. Our dataset consists of about 637 events with ML ranging between 0.8 and 4.7 from December 2018 to January 2019. We use this rich and large dataset for testing a workflow for automated processing. Earthquake location and clustering analysis show that seismicity is spatially clustered, with shallower events at the center of geothermal site in proximity to geothermal plants, and deeper earthquakes in the southern part of the study area. Most of our moment tensors can suggest the influence of geothermal activity and geothermal energy exploitation operations on the subsurface. This work is supported by the COSEISMIQ project of the EU GEOTHERMICA program .

How to cite: Rossi, C., Grigoli, F., Cesca, S., Heimann, S., Gasperini, P., Hjörleifsdóttir, V., Dahm, T., Bean, C. J., and Wiemer, S.: Analysis of microseismicity in the Hengill Geothermal Area, SW Iceland, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8704, https://doi.org/10.5194/egusphere-egu2020-8704, 2020.

EGU2020-16199 | Displays | ERE6.2

Contribution of continuous waveform processing to induced seismicity realtime monitoring during geothermal stimulation at Geldinganes, Iceland.

Francesco Grigoli, Sebastian Heimann, Claus Milkereit, Stefan Mikulla, Nima Nooshiri, Malte Metz, Gesa Petersen, Simone Cesca, Vala Hjörleifsdóttir, Rögnvaldur Magnússon, Ragnheidur St. Ásgeirsdóttir, Hannes Hofmann, Marco Broccardo, Dimitrios Karvounis, Arnaud Mignan, Kristjan Augustsson, Stefan Audunn Stefansson, Gunter Zimmermann, Torsten Dahm, and Stefan Wiemer

At Geldinganes Island, Reykjavik, Iceland a hydraulic stimulation was recently conducted to enhance the productivity of an existing hydrothermal well. An experimental cyclic soft stimulation concept was applied. Seismic risk was assessed with an appropriate monitoring network which was set up and operated before, during, and for some time after the stimulation activities. An advanced traffic light system was developed and operated for the first time in this setup.

A crucial element in such traffic light systems is the real-time monitoring of background and induced seismicity. During the experiment, real-time seismograms from the monitoring network were streamed over the internet to three different institutions (ISOR, ETHZ and GFZ), where they were analysed independently, with different combinations and setups of automatic, semi-automatic and manual methods. Both, classic pick based approaches and modern full-waveform methods were applied. Locations, magnitudes, and centroid moment tensor solutions were determined.

Many things can go wrong in real-time or near-real-time processing of seismic data. Sensor failures, transmission failures, timing issues, processing hardware failures, computational limitations, software bugs and human error, just to name a few. In a temporary network the challenges are additionally salted by the need to validate sensor responses, orientations, gain factors and site conditions in a short time frame between station setup and beginning of the experiment. Furthermore, tuning of advanced analysis methods can be difficult without example events at hand.

In this contribution, we would like to share our lessons learned in near-real-time processing of data from a heterogeneous temporary seismic network. 

How to cite: Grigoli, F., Heimann, S., Milkereit, C., Mikulla, S., Nooshiri, N., Metz, M., Petersen, G., Cesca, S., Hjörleifsdóttir, V., Magnússon, R., Ásgeirsdóttir, R. St., Hofmann, H., Broccardo, M., Karvounis, D., Mignan, A., Augustsson, K., Stefansson, S. A., Zimmermann, G., Dahm, T., and Wiemer, S.: Contribution of continuous waveform processing to induced seismicity realtime monitoring during geothermal stimulation at Geldinganes, Iceland. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16199, https://doi.org/10.5194/egusphere-egu2020-16199, 2020.

EGU2020-8462 | Displays | ERE6.2

Seismicity time evolution and 3D/4D seismic tomography of Nesjavellir geothermal field (Iceland)

Ortensia Amoroso, Ferdinando Napolitano, Vincenzo Convertito, Raffaella De Matteis, and Paolo Capuano

Nesjavellir Geothermal Field is located in the Northern part of the Hengill central volcano in South West Iceland. The Hengill volcanic complex consists of three smaller volcanic systems feeding several geothermal fields with surface manifestations.

Geothermal energy is currently produced at two power plants, in Nesjavellir and in Hellisheidi. After an exploitation period started in 1947, the construction of Nesjaveillir power plant was completed in 1990. Nowadays it produces geothermal energy of up to 300 MW, which is 1,640 l/sec of hot water and up to 120 MW of electricity.

Part of the surplus geothermal water from the plant goes into the injection wells and in analogy with the nearby Hellisheidi power plant the re-injection of geothermal gases into basaltic formations is planned. To this aim several tests of fluids deep injection are being conducted to prepare the experimental re-injection of carbon dioxide and hydrogen sulphide.

In the framework of the H2020-Science4CleanEnergy project, S4CE, a multi-disciplinary project aimed at understanding the underlying physical mechanisms underpinning sub-surface geo-energy operations and to measure, control and mitigate their environmental risks, we investigate the seismicity evolution through the b-value and study the elastic properties of the propagation medium through the 3D/4D seismic tomography.

The seismicity recorded in the study area is due to different mechanisms. Indeed, while in Hengill the seismicity is originated by volcano-tectonic processes, small earthquake swarms between Hengill and Grensdalur volcano are due to the geothermal activity. Finally, the seismicity in proximity of Hellishedi and Nesjaveiilir power plant appears to be induced by re-injection of waste water from the geothermal production.

Seismic data are recorded by the Icelandic Meteorological Office (IMO) but also from Iceland GeoSurvey (ÍSOR) and by the COSEISMIQ project. The production data are from the OR energy company.

We used an iterative linearized delay-time inversion to estimate both the 3D P and S velocity models and earthquake locations. The velocity model is parametrized by trilinear interpolation on a 3D grid. The inversion starts from the 1D velocity model, optimized for the area. Time variations of the medium seismic properties are observed in term of Vp, Vs and Vp/Vs ratio obtained by 4D tomography. The technique consists in applying the 3D tomography at consecutive epochs. Spatial and temporal characteristics of the re-located earthquakes are then analysed by using the ZMAP code to image the b-value in the investigate volume.

The images obtained for each epoch in terms of b-value, Vp and Vs velocities are then correlated with operational data.

 

This work has been supported by S4CE ("Science for Clean Energy") project, funded from the European Union’s Horizon 2020 - R&I Framework Programme, under grant agreement No 764810 and by PRIN-2017 MATISSE project funded by Italian Ministry of Education and Research.

How to cite: Amoroso, O., Napolitano, F., Convertito, V., De Matteis, R., and Capuano, P.: Seismicity time evolution and 3D/4D seismic tomography of Nesjavellir geothermal field (Iceland), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8462, https://doi.org/10.5194/egusphere-egu2020-8462, 2020.

EGU2020-13421 | Displays | ERE6.2

Seismic asperity size evolution during fluid injection: case study of the 1993 Soultz-sous-Forêts injection

Olivier Lengliné, Léna Cauchie, and Jean Schmittbuhl

The injection of fluid in the upper crust, notably for the development or exploitation of geothermal reservoirs, is often associated with the onset of induced seismicity. Although this process has been largely studied, it is not clear how the injected fluid influences the rupture size of the induced events. Here we re-investigate the induced earthquakes that occurred during an injection at Soultz-sous-Forêts, France in 1993 and studied the link between the injected fluid and the source properties of the numerous induced earthquakes. We take advantage that deep borehole accelerometers were running in the vicinity of the injection site. We estimate the moment and radius of all recorded events based on a spectral analysis and classify them into 663 repeating sequences.  We show that the events globally obey the typical scaling law between radius and moment. However, at the scale of the asperity, fluctuations of the moment are important while the radii remain similar suggesting a variable stress drop or a mechanism that prevents the growth of the rupture. This is confirmed by linking the event source size to the geomechanical history of the reservoir. In areas where aseismic slip on pre-existing faults has been evidenced, we observed only small rupture sizes whereas in part of the reservoir where seismicity is related to the creation of new fractures, a wider distribution and larger rupture sizes are promoted. Implications for detecting the transition between events related to pre-existing faults and the onset of fresh fractures are discussed.

How to cite: Lengliné, O., Cauchie, L., and Schmittbuhl, J.: Seismic asperity size evolution during fluid injection: case study of the 1993 Soultz-sous-Forêts injection, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13421, https://doi.org/10.5194/egusphere-egu2020-13421, 2020.

EGU2020-9942 | Displays | ERE6.2

Seismicity in the geothermal area of Mt. Amiata Volcano (Italy)

Michele D'Ambrosio, Carlo Giunchi, Davide Piccinini, Rebecca Bruni, and Gilberto Saccorotti

Located in the inner sector of the Northern Apennines (southern Tuscany), Mt. Amiata is a quaternary volcano that was active in between 0.3 My and 0.19 My b.p.. It now hosts a water-dominated geothermal field which is being exploited for the production of electric power since the early 1960s. Historical records report at least ten moderate (M < 5.3), yet damaging earthquakes, occurred well before the geothermal exploitation started. Nonetheless, public concern is rapidly raising due to the possibility that the geothermal production processes (i.e., vapor extraction and re-injection of condensates back into the subsurface) provoke stress perturbations that may trigger earthquakes. A critical issue thus consists in discerning whether seismicity is related to the exploitation of the geothermal resource, rather than to the natural tectonic stresses at the site. Here, we report data from a temporary seismic network operated at Mt Amiata during the 2016-2019 time span. We obtained precise, absolute locations using a non-linear probabilistic location procedure and a minimum-misfit, 1-D velocity model specifically derived for the area. Complementary information on the velocity structure was also derived from the inversion of the surface-wave group- and phase-velocity dispersion curves, as obtained from frequency-time analysis (FTAN) of regional earthquakes and noise correlation functions, respectively. Our catalog amounts to more than 1000 earthquakes, with a completeness magnitude of about 0.4. The improvement in earthquake detection with respect to the catalog from the national monitoring program is of the order of 1 magnitude unit. Hypocenters are clustered within a few, distinct focal volumes, two of which closely correspond to the productive fields. Most hypocenters are shallower than 5km, getting deeper as the distance from the geothermal areas increases. Overall, the lower bound of hypocentral depths follows the K-horizon, a regional-scale seismic reflector inferred to mark the upper limit of the brittle-to-ductile transition and, possibly, the top of the Pleistocene granitic intrusions. Throughout the observation period, the largest magnitude observed within the geothermal area is ML=2.9 (ML=2.1 in the national catalog); 95% of the earthquakes have magnitudes lower than 1. Earthquakes occur at a rather constant rate of less than 1 event/day, occasionally interspersed by short-duration (1-3 days), swarm-like bursts accounting for tens of earthquakes that do not exhibit any clear mainshock-aftershock sequence. The scaling relationships of the catalog are examined by computing clustering in the magnitude-distance-time space domains. The background and stationary components have similar relevance (55% and 45%, respectively), thus not resulting diagnostic about the principal driving mechanism of the observed seismicity. Although the proximity between the main focal volumes and production areas would suggest that geothermal exploitation plays a major role in the earthquake-generation process, the lack of any industrial data prevents from inferring any causative relationship between the two phenomena.

How to cite: D'Ambrosio, M., Giunchi, C., Piccinini, D., Bruni, R., and Saccorotti, G.: Seismicity in the geothermal area of Mt. Amiata Volcano (Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9942, https://doi.org/10.5194/egusphere-egu2020-9942, 2020.

EGU2020-2649 | Displays | ERE6.2

Lateral migration patterns toward or away from injection wells for earthquake clusters in Oklahoma

José Ángel López-Comino, Martin Galis, P. Martin Mai, Xiaowei Chen, and Daniel Stich

Exploring the connections between injection wells and seismic migration patterns is key to understanding processes controlling growth of fluid-injection induced seismicity. Numerous seismic clusters in Oklahoma have been associated with wastewater disposal operations, providing a unique opportunity to investigate migration directions of each cluster with respect to the injection-well locations. We introduce new directivity migration parameters to identify and quantify lateral migration toward or away from the injection wells. We take into account cumulative volume and injection rate from multiple injection wells. Our results suggest a weak relationship between migration direction and the cluster-well distances. Migration away from injection wells is found for distances shorter than 5-13 km, while an opposite migration towards the wells is observed for larger distances, suggesting an increasing influence of poroelastic stress changes. This finding is more stable when considering cumulative injected volume instead of injection rate. We do not observe any relationship between migration direction and injected volume or equivalent magnitudes.

How to cite: López-Comino, J. Á., Galis, M., Mai, P. M., Chen, X., and Stich, D.: Lateral migration patterns toward or away from injection wells for earthquake clusters in Oklahoma , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2649, https://doi.org/10.5194/egusphere-egu2020-2649, 2020.

EGU2020-7553 | Displays | ERE6.2

Exploring the Evolution and Source Properties of Injection-Induced Seismicity in Northern Oklahoma Using a Large-N Seismic Array

Kilian B. Kemna, Alexander Wickham-Piotrowski, Andrés F. Peña-Castro, Elizabeth S. Cochran, and Rebecca M. Harrington

The LArge-n Seismic Survey in Oklahoma (LASSO) array recorded local seismicity in 2016 in a region of active saltwater disposal. The month-long deployment of 1,833 vertical-component nodes had a nominal station spacing of 400 m and covered a 25 by 32 km2 area. We estimate local event magnitudes and focal mechanisms of the induced seismicity using the vertical component waveforms from a catalog of 1375 earthquakes. Here we use the developed catalog to investigate the spatio-temporal evolution of seismicity and the source properties of the induced events.

The catalog is complete to a local magnitude of ~0.9, with a b-value of ~1.1. Focal mechanisms, which we determined using the HASH method, show a mix of strike-slip and normal faulting. The majority of the events are located at 1.5 – 5.0 km depth, where injection depths range from 0.1 – 2.0 km, and the basement contact is located at 1.5 – 2.5 km. Analysis of the coefficient of variation of interevent times suggests that the time evolution of seismicity is close to Poissonian, with minimal temporal clustering. We observe spatial clustering, with larger (M > 2) events occurring within dense clusters near the footprint of the array.

The dense station coverage of the array permits the exploration of variations in corner frequency and resulting stress drop estimates as a function of azimuth, i.e. radiation pattern. We calculate stress drops for the local catalog within 5 km of the array footprint from individual spectral and spectral ratio corner frequency values. Single spectra corner frequency estimates for events within the array footprint on individual nodes show evidence of variation related to radiation pattern, and vary as much as 100% from the mean for an individual event. Stress drop estimates from spectral ratio corner frequency estimations range between 10 – 100 MPa, show self-similar scaling, and fall within the typical range observed for intraplate (tectonic) earthquakes. Both single spectra and spectral ratio corner frequency estimates show a significant sample bias in the corner frequency estimation by using less than ~10 stations, and highlight the importance of azimuthal coverage for the stability of spectral estimates.

How to cite: Kemna, K. B., Wickham-Piotrowski, A., Peña-Castro, A. F., Cochran, E. S., and Harrington, R. M.: Exploring the Evolution and Source Properties of Injection-Induced Seismicity in Northern Oklahoma Using a Large-N Seismic Array, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7553, https://doi.org/10.5194/egusphere-egu2020-7553, 2020.

EGU2020-8240 | Displays | ERE6.2

Earthquake source parameter analysis shows hydraulic fracturing induced events are consistent with fault reactivation under regional stress in northeastern British Columbia, Canada

Marco Pascal Roth, Alessandro Verdecchia, Kilian B. Kemna, John Onwuemeka, Rebecca M. Harrington, and Yajing Liu

An increasing number of M3+ earthquakes have been associated with Hydraulic Fracturing (HF) injection activity in low-permeable tight shale formations in the Western Canada Sedimentary Basin (WCSB) in the last decade. These include a Mw 4.6 on 08/17/2015 near Ft. St. John, a ML 4.5 on 11/30/2018, and two ML 3.2 on 10/05/2019, 10/08/2019 near Dawson Creek, British Columbia. Increased seismic activity in the Dawson-Septimus area prompted a temporary deployment of seismic stations in a joint effort between McGill University and the Ruhr University Bochum in order to perform higher-resolution monitoring relative to the regional seismic station coverage. Here, we use waveform data from that deployment of 22 (dominantly broadband) stations in close proximity to numerous HF wells in an area of roughly 60 x 70 km2, between July 2017 and August 2019, as well as records from 6 additional seismic stations northwest of the study area. In total, we detect 6222 local earthquakes, of which 5325 surpass a quality control criterion of having a horizontal location error ≤ 3 km. An investigation of the spatial and temporal correlation between injection and earthquake initiation using a cross-correlation based event similarity analysis during seismically active time periods reveals a high degree of event similarity within various clusters and a strong correlation with individual injection episodes at specific HF wells. In addition, event clusters also exhibit similar patterns in daily cumulative seismic moment, independent of differences in waveform characteristics.

As individual clusters may represent the activation of specific geological structures, we perform double-difference relative relocation of seismicity to identify fault orientations. In addition, we invert for focal mechanism solutions per event cluster to check consistency with structures inferred with relocated hypocenters, and perform spectral fitting for source parameter analysis. Event relocations are performed on individual families, where the total catalog is divided into subsets corresponding to 24 seismic active time periods where 43 event families are active. Relocating each earthquake family separately allows us to successfully relocate 4571 out of the total 5325 events. The relative relocations align in two dominant orientations, with one roughly perpendicular to the maximum horizontal regional stress orientation, and the other at low angles to the maximum regional stress orientation on a regional scale around individual HF wells. Focal mechanism estimates for events with M > 2.0 result in two primary groups of faulting mechanisms: strike-slip deformation on faults implied by lineations striking at low angles to SH, and thrust-faulting deformation on faults implied by lineations perpendicular to SH. Seismic moment and corner frequency estimates from single spectrum and spectral ratio fitting as well as scaling relations will be presented.

How to cite: Roth, M. P., Verdecchia, A., Kemna, K. B., Onwuemeka, J., Harrington, R. M., and Liu, Y.: Earthquake source parameter analysis shows hydraulic fracturing induced events are consistent with fault reactivation under regional stress in northeastern British Columbia, Canada, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8240, https://doi.org/10.5194/egusphere-egu2020-8240, 2020.

We conduct geomechanical study for a seismogenic fault in Hutubi underground gas storage site, northwestern China. The Hutubi reservoir has undergone active production from 1990s to 2012, leading to a complete depletion, and then sequential gas injection and extraction from 2013 for the gas storage project. First, we constrain the orientation and magnitudes of the stress state at the reservoir depths (~3.6 km depth) at the time of a complete depletion in 2012, using image-logged wellbore breakouts in a borehole. Then we estimate the variation of the stress state with time as a result of pore pressure change based on a simple assumption of coupling between horizontal stresses and pore pressure. Our results show that the stress state was initially in a reverse faulting regime before production and switched to a strike-slip faulting regime during production. Gas injection from 2013 turned the stress regime again in favor of reverse faulting. We use the estimated variation of the reservoir stress state with time to calculate temporal changes of slip tendency of the major earthquake fault (Hutubi fault) in the reservoir. Slip tendency of the fault decreased continuously with production, and then increased with injection. The first earthquake swarm associated with gas injection occurred ~2 months after the commencement of injection, possibly due to slow pore pressure diffusion. Thereafter, earthquakes were induced whenever gas was injected, while few earthquakes were detected during gas extraction phases. Our preliminary assessment of slip tendency suggests that earthquake swarms are induced during increasing phases of pore pressure when slip tendency reaches a value between 0.4 and 0.5, which can provide information on friction coefficient of the fault.

Funding information: This work is supported by the National Natural Science Foundation of China (41574088,41704096) 

How to cite: Gao, G., Chang, C., Wang, C., and Jia, J.: Variation of slip tendency of a seismogenic fault associated with fluid extraction and injection in the Hutubi underground gas storage, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7742, https://doi.org/10.5194/egusphere-egu2020-7742, 2020.

EGU2020-9168 | Displays | ERE6.2

New insights into the Pertusillo Lake reservoir induced seismicity (Italy) from a high-resolution matched-filter earthquake catalogue

Sonja Gaviano, Davide Piccinini, Luisa Valoroso, Luigi Improta, and Carlo Giunchi

The southern Apennines range hosts a well documented case of protracted Reservoir Induced Seismicity (RIS) associated to the Pertusillo artificial lake. Since the deployment of a local monitoring network in 2001, M3+ swarms were recorded to the south of this medium-sized water reservoir. Interpretation in terms of RIS relies on the positive correlation found between seasonal water level changes and earthquake rate that increases during the winter-spring refill. We present a new high-resolution catalogue of RIS obtained by running a matched-filter (MF) detection technique on data recorded during a dense passive survey between 2005-2006. We aim at producing a very-high quality catalogue in terms of completeness magnitude (Mc) and hypocenter location accuracy to precisely track the spatio-temporal distribution of seismicity, pinpoint the activated faults, investigate the rupture mechanisms and the role played by crustal fluids in triggering RIS. All these issues are critical to improve understanding of the physical mechanism behind the RIS.

Our initial catalogue includes 406 handpicked templates recorded by 3C 24-stations temporary network run by INGV. Local magnitudes range between 0.06 and 2.63, with a MC of 0.4. Templates are correlated to the 13-month-long data streams by the MF algorithm. A matched event is declared when the average value of cross-correlation function (CC) computed over all stations exceeds 0.65. The procedure furnishes 10056 matched events with associated P- and S-phase automatic picks, weighted according to the uncertainties of template event picks and the CC values of each trace. Matched events are preliminary located in a 1-D model using the NonLinLoc software and then selected based on quality criteria. The final catalog has MC=0.1 and includes 6012 high-quality events with ML > -0.9 that are then relocated through the high-precision double-difference relative technique. We recognize four main clusters confined at 2-6 km depth within a fractured, liquid-bearing carbonate antiform characterized by high-Vp (>6.0 km/s) and very-high Vp/Vs ratio (>2.0) that indicates high-pressure pore fluids. Hypocentral alignments delineate NW-trending high-angle faults dipping to the NE or SW that measure up to 2 km along strike and dip. Prevailing extensional focal mechanisms are coherent with the fault geometry and local stress field. These results suggest re-activation of inherited thrust-faults with associated back-thrusts optimally oriented in the present extensional stress field.  

The spatiotemporal seismicity distribution indicates a positive correlation between the seasonal oscillation of the lake level and the progressive activation of the 4 clusters of seismicity. Distant clusters from the PWR are delayed with respect to the closer ones, suggesting that seismicity migrates away from the reservoir following a pore fluid pressure triggering process. The b-value is high and it also varies with time between 1.2 and 1.8 with a trend anti-correlated to the lake level. Therefore, the proportion of large earthquakes to small ones increases during the re-fill stage characterized by intense earthquake production and vice-versa. The two southern clusters, more distant from the lake, with events that delineate clear fault-zones, share the lower b-values (1.4).

How to cite: Gaviano, S., Piccinini, D., Valoroso, L., Improta, L., and Giunchi, C.: New insights into the Pertusillo Lake reservoir induced seismicity (Italy) from a high-resolution matched-filter earthquake catalogue, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9168, https://doi.org/10.5194/egusphere-egu2020-9168, 2020.

EGU2020-10311 | Displays | ERE6.2

Underground seasonal storage of gas: testing numerical modelling tools with application to i) a deep aquifer-layer, and ii) salt caverns.

Francesca Silverii, Djamil Al-Halbouni, Magdalena Stefanova Vassileva, Gudrun Richter, Rongjiang Wang, Borja Gonzalez Cansado, Sebastian Hainzl, Torsten Dahm, and Francesco Maccaferri

Within the framework of the SECURE project, we test modeling techniques used for natural geothermal and volcanic reservoirs and apply them to anthropic underground gas storage facilities. These systems indeed share similar mechanics and physical properties, however gas reservoirs are often extensively monitored, and better imaged. In order to manage fluctuations between gas supply and demand, natural gas can be temporarily stored in different underground storage facilities, such as depleted gas/oil fields, natural aquifers, and salt cavern formations. When properly monitored during storage and withdrawal (production) of gas, these systems provide a unique opportunity to investigate how reservoirs evolve at different time scales, modify the surrounding stress state, produce deformation coupled with diffusion processes, and possibly induce/trigger earthquakes on nearby faults.

In the first case study we addressed within the framework of SECURE project, we take advantage of well constrained reservoir geometry and physical parameters, records of gas injection/production rates, pore pressure variations, and a local seismic catalog at a gas reservoir in Spain. We implement a poro-elastic model to simulate pressure temporal variations, estimate related stress-state variations, and study eventual relationship with small recorded seismic events. The model is based the software POEL by Wang et al., (2003), a semi-analytical physics-based numerical scheme which allows the computation of transient and steady-state solutions in response to pore-pressure variations. Being 2D axisymmetric, POEL drastically simplify the geometry of the reservoir, but it is particularly suitable to link observables such as pressure variations within the reservoir with the physical/mechanical processes occurring in the surroundings.

In the second case study we address the stability condition for salt caverns which has been excavated for salt mining purposes. We make use of 2D discrete-element geomechanical models to compare numerical simulation results with field observations in terms of surface subsidence. With this numerical model we consider different pressure conditions for the fluid (brine) filling the cavity, and return different scenarios for the stability of a salt cavern. Such modeling effort aims at improving our understanding of middle-to-long term stability conditions, for those cavities that have been dismissed after anthropic operations such as salt extraction, but also seasonal gas storage.

How to cite: Silverii, F., Al-Halbouni, D., Stefanova Vassileva, M., Richter, G., Wang, R., Gonzalez Cansado, B., Hainzl, S., Dahm, T., and Maccaferri, F.: Underground seasonal storage of gas: testing numerical modelling tools with application to i) a deep aquifer-layer, and ii) salt caverns., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10311, https://doi.org/10.5194/egusphere-egu2020-10311, 2020.

EGU2020-9984 | Displays | ERE6.2

Spatial and temporal evolution of micro-earthquakes during Multi-cycle operation of the Hutubi underground gas storage, Xinjiang, China

Bo Zhang, Baoshan Wang, Zhanbo Ji, Jinxin Hou, Lu Li, Bin Wei, Nier Wu, and Zhide Wu

Underground Gas Storages (UGSs) are important large-scale industrial facilities used to bridge the gap between the natural gas demand and supply. The UGS production can cause periodical changes of the subsurface stresses and probably change the seismicity pattern. The UGS operation related seismicity has important affects on the UGS, but is rarely reported. Hutubi UGS is the largest Underground Gas Storage in China and well equipped with seismic observations from the beginning of the UGS operation in Jun. 2013. The Hutubi UGS provides an unprecedented opportunity to study the seismicity related gas injection. The seismicity around the Hutubi UGS was detected and located by using matched filter and double difference relocation techniques. More than 7000 earthquakes were detected and located within 20 km of the UGS from Jan. 2011 to Dec. 2018 (i.e., 2 years before the operation and 6 injection-extraction cycles). The seismicity can be clustered into three groups South of, North of, and beneath the UGS. Two (South and North) of three groups occurred along two south-dipping planes with dipping angle ~40 degree, corresponding to local geological structures. While the underlaying group occurred along the direction conjugate to the other two groups, which was in accordance with the starting of the second injection stage and gradually migrated deeper. The northern cluster occurred mainly after the Murghob earthquake (M7.2) and the Hutubi earthquake (M6.2), which may be related to dynamic stress triggering from these two earthquakes. The seismicity in the southern cluster persists, but the rate shows seasonality, which is likely modulated by the gas operation and underground water exploitation. The seismicity in the Hutubi UGS area may have different origins. Understanding the mechanism of the impact of UGS operation on different clustering seismicity will help us to optimize the production parameters and reduce the risk of induced earthquake.

How to cite: Zhang, B., Wang, B., Ji, Z., Hou, J., Li, L., Wei, B., Wu, N., and Wu, Z.: Spatial and temporal evolution of micro-earthquakes during Multi-cycle operation of the Hutubi underground gas storage, Xinjiang, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9984, https://doi.org/10.5194/egusphere-egu2020-9984, 2020.

Seismicity related to fluid injection during unconventional oil and gas exploration has increased dramatically in North America in the last decade. The Western Canadian Sedimentary Basin experienced a significant increase in the number of M3+ earthquakes, including several M4+ associated with high-pressure stimulation during Hydraulic Fracturing (HF) activity. The vigorous seismic response to injection activity and low historical seismicity rates pose critical questions as to the triggering mechanism(s) and seismic hazard assessment in the affected areas. To monitor seismicity linked to injection, a dense local network of eight broadband seismic stations was installed in 2015 at distances of ~2 km around an active well pad with the purpose of monitoring seismicity prior to, and following, a HF well stimulation in the Montney Play in British Columbia, Canada. Here we present an earthquake source process study using observations from the local station network, and provide evidence for a slow-rupture seismic signal which may bridge the spectrum of fault slip rates from aseismic near the well bore, to typical seismic velocities at distances beyond ~1 km.

Initial detection and relocation of seismicity between May 28 – October 15, 2015 yielded 350 well-constrained hypocenters of high-frequency events with a maximum magnitude of Mw 1.8 that resemble typical tectonically generated earthquakes. The detection procedure also yielded a total of 31 events with high-frequency (or broadband) onsets, that transition to protracted, low-frequency ringing relative to event magnitude, which we term hybrids. Both hybrid and high-frequency events occur at similar depths to the active well bore and at distances of ~1-2 km from injection stages, yet exhibit varying source characteristics in spite of their proximal source volumes. Hybrid waveforms are marked by broader P- and S-wave arrival pulse shapes, and spectral fitting suggests that the stress drop values are roughly an order of magnitude lower than high-frequency events, with average static stress drop values of 0.3 MPa and 4.9 MPa, respectively. We interpret wider phase arrival pulse widths and lower stress drop values as resulting from lower rupture velocities of hybrid events relative to high-frequency events. A dilatant strengthening effect would be expected in close proximity to the well bore, and near the hybrid sources, where material is weaker and pore pressures are elevated, which may result in slower rupture propagation when slip is initiated relative to further distances where material damage and pore pressure perturbation are both lower. Thus, hybrid earthquakes may mark regions where slip velocities transition from aseismic sliding directly next to the well bore, which has been observed in laboratory and meso-scale experiments, to typical seismic velocities at further distances. The size-duration scaling of the induced hybrids observed here also extends the scaling of slow earthquakes occurring in tectonic fault transition zones, and may provide the first observations to extend the scaling down to seismic moment values of ~1010.

How to cite: Harrington, R. M., Yu, H., Kao, H., Liu, Y., and Wang, B.: Hydraulic fracturing induced hybrid earthquakes in the Montney Basin, British Columbia, Canada may mark the transition from aseismic slip near the wellbore to seismic slip at greater distances, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4544, https://doi.org/10.5194/egusphere-egu2020-4544, 2020.

Hydraulic fracturing underpins tight shale gas exploration but can induce seismicity. During stimulations, operators carefully monitor the spatio-temporal distribution and source parameters of seismic events to be able to respond to any changes and potentially reduce the chances of fault reactivation. Downhole arrays of geophones offer unique access to (sub) microseismic source parameters and can provide new insights into the processes that induce seismicity. For example, variations in stress drop might indicate changes in the seismic response to injection (e.g. pore pressure variations). However, borehole arrays of geophones and the high frequencies of small events also present new challenges for source characterization. Stress drop depends on the corner frequency, a parameter with great uncertainty that is sensitive to attenuation, especially for (sub-) microseismicity. Here, we explore the behavior of microseismic spectra measured along borehole arrays and the effect of attenuation on estimates of corner frequency. We examine a dataset of over 90,000 microseismic events recorded during hydraulic fracturing in the Horn River Basin, British Columbia. We only see clear phase arrivals for events Mw > -1 and restrict our initial analysis to a subsample of Mw> 0 events that vary in space and time.

Our first observation is that some stations in the borehole array show an unexpected increase in the displacement energy from the low frequency to the corner frequency in the P and SH phases as well as high-frequency energy spikes inconsistent with a smooth Brune source model. A shorter time window that only captures the direct arrival results in a flatter low frequency plateau and reduces the amplitude of the pulses but compromises the resolution. The spikes may be caused by high frequency coda energy. We also find that corner frequency estimates decrease with decreasing station depth along the array in both the P and SH phases, a likely result of high frequency attenuation along the downhole array. The findings suggest Brune corner frequencies of moment magnitudes < 0.5 may not be resolvable even with downhole arrays at close proximity. Our results will eventually contribute to a better characterization of microseismic source parameters measured in borehole arrays.

 

How to cite: Klinger, A. and Werner, M.: Insights into downhole array spectra of hydraulic-fracturing induced seismicity in the Horn River Basin, British Columbia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20394, https://doi.org/10.5194/egusphere-egu2020-20394, 2020.

Recent examples have shown that fluid injection during hydraulic fracturing can result in felt, or even damaging, seismic activity. In the vicinity of the Preston New Road site (Lancashire, UK), almost 200 earthquakes of ML -0.8 to 2.9 have been recorded by the British Geological Survey (BGS) over the period from October 15th 2018 to September 2019. This corresponds to the period during which hydraulic fracturing (fracking) was carried out by the operator, Cuadrilla Resources. Throughout the operation, fracking had to be suspended temporarily five times as the ML 0.5 ‘red light’ of the UK regulatory Traffic Light System (TLS) was exceeded. Since 2017, the University of Liverpool has operated a seismic monitoring network comprising nine broadband Nanometrics Trillium 120 across the Blackpool-Preston region in order to determine the baseline seismicity and monitor induced events associated with the fracking operations atthe site. In addition to this network, both Cuadrilla and the BGS deployedseismometers-including borehole geophone strings-over the region making it oneof the best places in Europe for monitoring induced seismicity. The superficial geology of the region is dominated by thick sand, till and clay deposits, poten-tially leading to significant amplification of seismic waves. This amplification may lead to over-estimation of earthquake magnitude, and therefore increased likelihood of triggering mitigation measures associated with the TLS. In order to understand amplification effects near the PNR site, surface-wave measurements (both MASW and seismic Ambient Vibration Arrays, AVAs) have been used to derive dispersion curves and obtain VS profiles through an inversion process for station-site characterization. By using small local arrays (hundreds of meters wide) to regional arrays (tens of km wide), we reconstruct a velocity model down to the bedrock depth. This velocity model can then be used to compute a parshly non-ergodic ground motion and subsequently seismic hazard assessment. This approach allow us to account for site to site variability and result in reduced uncertainty in the hazard assessment. We find Vs30 in the range 200 – 300 m/s at the sites investigated, leading to significant amplification effects that may bias event magnitudes determined on a surface array.

How to cite: Delvoye, A. and Edwards, B.: Induced Seismicity at the Preston New Road Shale Gas Site in Lancashire, UK – Site Characterisation and impact on the TLS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20620, https://doi.org/10.5194/egusphere-egu2020-20620, 2020.

EGU2020-10905 | Displays | ERE6.2

Spatiotemporal modelling of induced seismicity with a stress-based statistical approach applied to different production sites

Gudrun Richter, Sebastian Hainzl, Peter Niemz, Francesca Silverii, Torsten Dahm, Gert Zöller, Arno Zang, and Francesco Maccaferri

In the framework of the Geo:N project SECURE (Sustainable dEployment and Conservation of Underground Reservoirs and Environment) we developed a Python software toolbox to model the rate and distribution of seismicity induced by anthropogenic stress changes at various production sites (gas production, hydrofracturing, gas storage). This toolbox tests different frictional behavior of the underground (linear or rate-and-state stressing rate dependent, critically or subcritically prestressed faults) and takes into account the uncertainties of the production site parameters. The knowledge on the location and orientation of pre-existing faults can be considered as well. Model parameters are estimated by fitting the model to recorded historical seismicity using a maximum likelihood approach. We discuss applications at conventional gas fields, hydraulic fracturing experiments and an aquifer gas storage site, covering a wide range of spatial and temporal scales of induced seismicity in different settings and for different production schemes. This enables to investigate the underlying physical processes by the comparison of the different models. Additionally, the model parameters are linked to frictional material properties and the best performing model can be used to forecast the seismicity rates in space and time with their uncertainties according to the production plans.

Induced seismicity at gas fields in the Northern Netherlands and in Germany have similar tectonic settings but very different extents, depths and production histories. The data set of two sites are compared which both show a large delay of the first recorded seismicity after the start of production. Using our model we can reproduce the long delay for both sites. Thanks to the long and detailed data set we successfully reproduce the spatiotemporal pattern of the seismicity of one site, whereas the limited number of seismic events result in large uncertainties for the other site. In the comparative testing of the models the critically prestressed rate-and-state model performs best. This means that the complete stressing history influences the resulting seismicity. We also applied the model to a hydraulic fracturing experiment in granite comparing data sets for different fracturing methods and different phases of a stimulation experiment. Hundreds of microearthquakes are localized in a volume of roughly 15x15m with increasing number of events for later refraction stages indicating the growth of rock fracturing. A third application is run for a gas storage in an aquifer layer, which is loaded by injection and production operations. Here the proportion of the tectonic versus the anthropogenic induced seismicity is investigated analyzing the varying number of small local earthquakes in the region.

How to cite: Richter, G., Hainzl, S., Niemz, P., Silverii, F., Dahm, T., Zöller, G., Zang, A., and Maccaferri, F.: Spatiotemporal modelling of induced seismicity with a stress-based statistical approach applied to different production sites, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10905, https://doi.org/10.5194/egusphere-egu2020-10905, 2020.

EGU2020-11794 | Displays | ERE6.2

Ground Motion Prediction Equations for shallow, small-magnitude events: application to the Mirandola-Cavone oil field

Elisa Venturini, Licia Faenza, Irene Munafò, Mario Anselmi, Lucia Zaccarelli, Alexander Garcia‐Aristizabal, and Andrea Morelli

Ground motion prediction equations (GMPEs) based on data collected on hydrocarbon extraction areas have to deal with lower magnitude and smaller distances compared to the natural seismicity. This study focuses on the Mirandola-Cavone oil field located in the Po Plain (Northern Italy), an area that has been struck by the Emilia earthquake sequence in 2012.
We start with the compilation of a new homogeneous seismic catalogue, in terms of locations and moment magnitudes. The data come from the local network run by the industrial operator, integrated by the closest stations of the Italian seismic network managed by Istituto Nazionale di Geofisica e Vulcanologia.
Subsequently, we calculate the intensity parameters of interest (e.g., Peak Ground Acceleration, Peak Ground Velocity and spectral values) for the available set of about 250 earthquakes.
Lastly, we develop a functional form for the GMPE using software tools available at  IS-EPOS Platform, derived for the geometrical mean of the horizontal components of seismograms. The resulting attenuation curve is calibrated for magnitudes higher than 0.1 and distances up to 50 km, appropriate for monitoring local seismicity. This work represents the first attempt to construct the GMPEs for an oil field in Italy, starting from the raw data, in support to the Italian Guidelines for monitoring seismicity, deformation and pore pressure in hydrocarbon extraction areas.

How to cite: Venturini, E., Faenza, L., Munafò, I., Anselmi, M., Zaccarelli, L., Garcia‐Aristizabal, A., and Morelli, A.: Ground Motion Prediction Equations for shallow, small-magnitude events: application to the Mirandola-Cavone oil field, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11794, https://doi.org/10.5194/egusphere-egu2020-11794, 2020.

EGU2020-21210 | Displays | ERE6.2

The Mw 4.9 Le Teil seismic event (France): a possible case of triggered seismicity

Vincenzo Convertito, Vincenzo De Novellis, Francesco Casu, Riccardo Lanari, Fernando Monterroso, Sotiris Valkaniotis, and Nicola Alessandro Pino

In the last decades, the triggered seismicity has represented one of the most debated issue. Fluid pressure changes with/without fluid flow in rock fractures/pores, thermal stress changes due to temperature gradients, and the volumetric changes or mass removal/accumulation can be included in the geoengineering processes that can induce or trigger seismic activity.

In this work we analyse the Le Teil earthquake (LTe), which occurred on November 11, 2019 (MW 4.9) in Ardèche region (south-eastern France), as a possible triggered event originated by rock mass removal in the Lafarge quarry operating since 1833. The structural area where LTe occurred is part of the St. Thomé‐La Rouvière fault system, located in the Cévennes fault bundle, which marks the south-eastern border of the Massif central over almost 150 km long; this fault presents a NE-SW trend and its geometry characterized by several uncertainties due to the absence of dip measurements.

As first step, to estimate the removed volume of rock in the Lafarge quarry, we use multi-temporal digital surface models and, in particular, the archive stereo aerial image pairs from IGN for 1946, 1979, 2007 and 2011; our analysis is restricted to the modern period where detailed topographic data are available. Subsequently, we generate the coseismic deformation maps by applying the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique to SAR data collected along ascending and descending orbits by the Sentinel-1 (S1) constellation of the European Copernicus Programme. In order to retrieve the seismogenic fault parameters, we jointly invert the so-generated S1 DInSAR measurements by performing a consolidated two-step approach: it consists of a non-linear optimization to constrain the fault geometry with uniform slip, followed by a linear inversion to retrieve the slip distribution on the fault plane.

Finally, our Coulomb stress changes analysis on the fault along the slip direction suggests a clear positive triggering relation between the long-term activity in the Lafarge quarry and the Le Teil earthquake.

This work is supported by: the 2019-2021 IREA-CNR and Italian Civil Protection Department agreement; the EPOS-SP project (GA 871121); and the I-AMICA (PONa3_00363) project.

How to cite: Convertito, V., De Novellis, V., Casu, F., Lanari, R., Monterroso, F., Valkaniotis, S., and Pino, N. A.: The Mw 4.9 Le Teil seismic event (France): a possible case of triggered seismicity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21210, https://doi.org/10.5194/egusphere-egu2020-21210, 2020.

Induced and triggered seismicity in Germany is related to various mining operations such as hydrocarbon extraction, geothermal exploitation and classical mining techniques, i.e. coal and potash mining.

After some larger events small damages to buildings were observed that might have been caused by the ground shakings. This led to public discussions on compensation and to political discussions on improving legal regulations. The possibility of damages caused by mining induced seismic events and difficulties in financial compensation reduced the acceptance of mining projects in the past, e.g. geothermal projects are inhibited.

In case of verified damage due to an induced event, the causative mining company has to pay compensations. In 2016 new legal regulations entered into force. The Federal Mining Act was revised with an improved legal situation for the population by expanding the prima facie evidence on mining activities using boreholes. The new legal regulations define, that damages at buildings are assumed to be caused by the seismic event in the responsibility of the operator of the mining activities, if they occur within a certain area defined by the mining authority (impact area, German: “Einwirkungsbereich”).

From the seismological perspective, local measurements of PGV are often rare. Thus, it is difficult to assess the damage potential of the seismic events in detail, especially if intensities are around V (EMS-98). In many cases, a relation between individual damages at buildings and the seismic event is only hardly verifiable. Actually, detailed survey reports could neither prove nor disprove the relation between damages and seismic events in some cases. In conclusion, some of the widely discussed events might have led to small damages.

A brief introduction about the existing legal regulations will be presented. We used synthetic seismogram to model the wave propagation and amplitude effects for induced seismic events in the magnitude range between ML 2.9 and 3.6, for which it was necessary to define the impact area for legal regulations. Results from amplitude measurements at existing seismic stations were taken to calibrate the absolute amplitudes of the modeling. The synthetic seismograms could help to quantify the effects from the radiation pattern of the source and the impact of sediment coverage between source and receivers. They could improve the definition of the area of impact.

How to cite: Gestermann, N. and Plenefisch, T.: Synthetic seismograms for assessing areas of potential damage after induced events for legal regulations in Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9381, https://doi.org/10.5194/egusphere-egu2020-9381, 2020.

EGU2020-20078 | Displays | ERE6.2

Seismicity in the Northern German basin - from simple model to complex regime

Gregor Mokelke and Manfred Joswig

The Nothern German basin was considered aseismic in most of the seismic hazard maps of last century. Then seismic events occurred in the last decades, and were located in the vicinity of gas production. Until now more than 70 earthquakes are documented with magnitudes ranging from ML 1.0 to 4.5. Especially the 2004 Rotenburg ML 4.5 event caused much concern, and first locations of different authors disagreed in depth. Dahm et al (2007) argued for 5 km depth close to the horizons of gas production, and suggested a depletion-induced event. Macroseismic studies and other authors, however, determined focal depths of 8-12 km, clearly below gas production.
Within the last 15 years new stations from BGR (Bundesanstalt für Geologie und Rohstoffe) and the BVEG (Bundesverband Erdöl, Erdgas und Geoenergie e.V.) were established in the region between Cloppenburg and Soltau. Our own work is based on a small-scaled, but dense network with arrays and single stations that were installed from 2014 to 2018 in the eastern central part of the gas fields near Rotenburg. Results resolve that seismic activity can occur in a great range of depths down to 30 km, and it is not exclusively focussed on the reservoir horizons. We found strong dependence of depth determinations from parameter settings – notably vP/vS – and station selection. Besides obvious mis-locations of weak, low SNR events based on few phase readings we also traced this dependency back to the 2004 Rotenburg event which at that time was recorded only by a sparse network of remote stations.
In summary, the Northern German basin offers a complex regime of weak seismicity, ranging from single low-crust earthquakes to frequent, induced events of gas production. The 2004 Rotenburg event does not fit either category, and geomechanical modelling will be needed to decide on its relation to gas production.

How to cite: Mokelke, G. and Joswig, M.: Seismicity in the Northern German basin - from simple model to complex regime, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20078, https://doi.org/10.5194/egusphere-egu2020-20078, 2020.

EGU2020-12786 | Displays | ERE6.2

Seismic Monitoring for High-Precision Delineation of Fault Geometry and Stress; Case Study for the West Texas Subscription Array

Sepideh Karimi, Adam Baig, Aaron Booterbaugh, Yoones Vaezi, Mark Stacey, Dario Baturan, and Benjamin Witten

Seismicity potentially induced through wastewater disposal, hydraulic fracture completion, or other industrial operations, has been a cause for increasing public concern over the last decade. Monitoring for this activity has focussed on the problems of location and characterization, often to a relatively rough degree of precision. Regulations typically spell out responses for operators should an event exceed a magnitude threshold within a specified distance of their facilities. While this type of monitoring is critical for ensuring injections be conducted effectively while minimizing potential damage from shaking and public alarm, it often leaves many unanswered questions in terms of the underlying processes.

Understanding these questions entails that we demand more out of the seismic networks, essentially upgrading the data products to a “next generation” level.  The data from the network needs to be used to provide a detailed understanding of critical geological structures and geomechanics of the study area. This goal is facilitated through both a densification of hardware and a higher order of event processing. High-precision locations delivered through relative relocation methodologies delineate slipping fault structures, often resolving previously unknown features. Moment tensor inversion processing also helps reveal the orientations of faults and provides information on stress in the region. The resolution of these structures provides critical insight into understanding how a field is reacting.

We illustrate the application of this “next-generation” seismicity monitoring system to the Delaware Basin in West Texas, where we have deployed a network of 25 broadband seismometers complementing monitoring from TexNet and other networks. Despite being an exceptionally challenging recording environment, by aggregating all of these data we obtain a high-resolution catalog of earthquake hypocenters delineating a number of fault features. Inverting the stresses from the moment tensors of the highest-quality events shows a dominantly normal stress regime and tangibly resolves a rotation of axes transitioning across the basin. We illustrate both the logistical and processing requirements necessary for timely delivery of results highlighting the dynamics of seismicity in an active study area.

How to cite: Karimi, S., Baig, A., Booterbaugh, A., Vaezi, Y., Stacey, M., Baturan, D., and Witten, B.: Seismic Monitoring for High-Precision Delineation of Fault Geometry and Stress; Case Study for the West Texas Subscription Array, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12786, https://doi.org/10.5194/egusphere-egu2020-12786, 2020.

Previous studies of microseismic noise before earthquakes in seismically active regions showed the possibility of detecting the preparation processes of seismic events. This effect manifests itself as decrease of the frequency of natural oscillations before earthquakes. In this work, the method for detecting the natural frequencies of blocks in seismic noise is adapted to a lower hierarchical level. Using known empirical relations for faults with a characteristic length of less than 500-1000 m, the characteristic natural oscillation frequencies that can be used to diagnose a fault zone are estimated. For small seismic events with magnitudes Mw from -2 to -1, we calculated the expected frequencies of natural vibrations of 350-1100 Hz, and for events with Mw from 0 to 1,  - below 35 Hz. For analysis, we used the recording data of high-frequency accelerometers at a depth of 300 m from the free surface in the area of the city of Gubkin (Russia) within iron ore deposits. Before small events with an amplitude of more than 0.01 m/s2. The intervals of decrease in the spectral centroid in the range of 20-1200 Hz were identified. The minimum values of the spectral centroid obtained on the basis of experimental data are generally in a good agreement with theoretical estimates. This work was supported by RFBR (project # 18-05-00923).

How to cite: Besedina, A. and Pavlov, D.: Development of the method for detecting natural frequencies of blocks in seismic noise before small seismic events, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18098, https://doi.org/10.5194/egusphere-egu2020-18098, 2020.

EGU2020-3912 | Displays | ERE6.2

Realtime detection and location of very local seismicity using SeisComp3

Marcelo Bianchi, Lucas Schirbel, and Alexandre Ausgusto

We put SeisComp3 to test by using it to analyze a very dense (9 squared kilometers) local network of 712, four components sensors (stations). Each station had a 3-component accelerometer and a pressure sensor deployed at the ocean bottom, close to the Brazilian platform near an oil exploration field. Noise levels were extreme. During the two months of the operation time, the network recorded an earthquake swarm sequence, and later analysis indicated more than 1000 earthquakes detected in a one-hour interval employing a coherency stacking method. While still not a common practice, real-time earthquake detection and location in this situation would be beneficial since this could support decisions while drilling or oil recovering is in place. Traditional tools as SeisComp3 are routinely used and allows for real-time detection and location along with the rapid revision of regional and teleseismic events, but are not widely adapted to work in a very local environment. Our experience so far showed that SeisComp3 efficiently handled the data volume (4 components at 500 samples per second times 712 stations) with a modern average workstation. Traditional SEG-Y data can be routinely converted and fed in real-time to SeedLink FIFO using ObsPy. Still, data must be correctly rotated since SeisComp3 needs at least a vertical component. Processing workflow included parallel picking using scautopick with STA/LTA, nucleation of origins using scautoloc, and location using Locsat and Hypo71 tools. In this harsh environment, the optimal window size for STA is about the size of the P-wave (0.05-0.1 s) and, LTA is about 30-60 times the S-P times (60-120 s). Using those parameters, SeisComp3 managed to generate from 400-1200 readings per data channel. We fed all picks into scautoloc that handled origin nucleation and location. Despite parameters supplied to scautoloc, the tool has many limits and relations hardcoded that inhibit it from respecting maximum requested residuals. In other words, its nucleation algorithm is adapted to work on the teleseismic and regional scale. Actual results indicate that we were able to nucleate and locate only 10-20% of known origins. Due to the flexibility of the tool, we also developed a pipeline using S-waves only. S-waves had a higher SNR for the events of interest and, due to lower velocities, presents a larger moveout on the small array easing the location. Manually picked and relocated detections returned an RMS lower as 0.04 s. Additional tests performed using the Scanloc module (GEMPA closed source nucleator) showed a higher performance during the nucleation of new origins. In this case, Hypo71 was the used locator. We did not observe any clear difference between LocSat and Hypo71 performance once the earthquake source is nucleated, and a proper velocity model is supplied.

How to cite: Bianchi, M., Schirbel, L., and Ausgusto, A.: Realtime detection and location of very local seismicity using SeisComp3, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3912, https://doi.org/10.5194/egusphere-egu2020-3912, 2020.

EGU2020-3965 | Displays | ERE6.2

Earthquake-induced site effect in the oil field deposit of Absheron peninsula (Azerbaijan)

Gulam Babayev and Fakhraddin Kadirov (Gadirov)

Absheron peninsula (Azerbaijan) area was hit by the strong Caspian earthquakes on November 25, 2000 with Mw6.1 and 6.2 magnitudes. The seismic networks successfully recorded the foreshock, main shock and many aftershocks at respective locations. By using probabilistic analysis, magnitude of design earthquake for the current study in the oilfield was taken as 6.3. From this concept design (scenario) earthquake, accelerations were estimated for the distance of 35 km. In the second phase of the study, soil amplification factors and site characteristics data from boreholes were determined and estimated. In the next phase, the study uses synthesized accelerograms formed on the basis of simulation of the seismic wave propagation processes through ground layer aiming to determine the quantitative characteristics of seismic effect on the oilfield region. Soil amplification values estimated by empirical relationships in terms of shear wave velocities are in the range of 0.7 and 1.9 values. Shear wave velocity (Vs, 30) values are 100 and 110 (m/s). The PGA values for the study area were evaluated by considering the local site effects. Peak ground acceleration varies between 100 – 380 gal. On the basis of the empirical relationship between MSK-64 and peak ground acceleration, the special distribution of intensity of the design earthquake with intensity of >8 is represented. Finally, the study presents possible relationship between seismic effect and daily oil recovery which states the direct proportional characteristics.

Keywords: ground classification, oilfield, scenario earthquake, Vs30, amplification factor, peak ground acceleration

How to cite: Babayev, G. and Kadirov (Gadirov), F.: Earthquake-induced site effect in the oil field deposit of Absheron peninsula (Azerbaijan), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3965, https://doi.org/10.5194/egusphere-egu2020-3965, 2020.

EGU2020-12096 | Displays | ERE6.2

Induced or triggered? The deadly February 2019 Rongxian-Weiyuan ML 4.9 earthquake in the shale gas field in Sichuan, China

Hongfeng Yang, Pengcheng Zhou, Nan Fang, Gaohua Zhu, Wenbin Xu, Jinrong Su, Fanbao Meng, and Risheng Chu

Coinciding with the extensive hydraulic fracturing activities in the southern Sichuan basin, seismicity in the region has surged in the past a few years, including a number of earthquakes with magnitudes larger than 5. On 25 February 2019, an ML4.9 earthquake struck the Rongxian County, Sichuan, China and caused 2 fatalities and 12 injuries, the first deadly earthquake associated with shale gas production. The earthquake was preceded by two foreshocks with magnitudes of ML4.7 and ML4.3 within two days. We relocated the earthquake sequence using local and regional seismic network, and obtained the focal depths of the mainshock and two foreshocks at 1 and 3 km, respectively, much shallower than the report from catalogue. Most other smaller quakes were located at 2-6 km. The mainshock had also been well captured by InSAR images, which confirmed the shallow depth of ~1 km. Both seismic and geodetic data yielded thrust faulting mechanism for the mainshock, consistent with the mapped Molin fault in the region. The two foreshocks, however, occurred on an unmapped fault that has different orientation than the Molin fault. Injection wells are found in the vicinity of the two foreshocks and the fracking depth (~2.7 km) coincides with their focal depths, suggesting a possible causal relationship. The mainshock is located in the region with positive Coulomb failure stress caused the two foreshocks. The value of Coulomb failure stress change is 0.03 bar, smaller than the typical static triggering threshold. Therefore, the mainshock is likely caused by fracking by poroelastic stress transfer.

How to cite: Yang, H., Zhou, P., Fang, N., Zhu, G., Xu, W., Su, J., Meng, F., and Chu, R.: Induced or triggered? The deadly February 2019 Rongxian-Weiyuan ML 4.9 earthquake in the shale gas field in Sichuan, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12096, https://doi.org/10.5194/egusphere-egu2020-12096, 2020.

ERE6.3 – FRACTURES: Breaking the Laws

EGU2020-13670 | Displays | ERE6.3

Determination of hydraulic, mechanical and chemical fracture apertures

Philipp Blum, Sina Hale, Chaojie Cheng, Tobias Kling, Frank Wendler, Lars Pastewka, and Harald Milsch

In various reservoirs such as geothermal reservoirs or host rocks for nuclear waste, fractures and in particular fracture apertures play a crucial role in acting as conduits or even barriers, and therefore control fluid flow and solute transport in such reservoirs or host rocks. Often such reservoirs are simulated by discrete fracture network (DFN) models, whose performance however rely strongly on reliable input parameters such as fracture apertures under different conditions. Hence, in this study we examine various novel field and numerical methods, which are able to determine hydraulic, mechanical and even chemical apertures of natural fractures. First, we compare three different methods, (1) syringe air permeameter, (2) microscope camera and (3) laser scanner for determining hydraulic fracture apertures. Our results prove that the air permeameter allows direct and reliable measurements of hydraulic apertures in the laboratory and also in the field. Additionally, the novel air permeameter could be successfully validated by flow through experiments using various types of fractured core samples. In contrast, microscope camera and laser scanner only provide reliable mechanical apertures. In order to also simulate fracture closure under normal stresses, an innovative contact mechanical approach is introduced and validated using a granodiorite fracture. The simulations indicate the best performance for an elastic–plastic (EP) model, which fits almost perfectly the experimentally derived normal closure data. Finally, a phase-field model (PFM) for hydro­thermally induced quartz growth is used to understand the effect of sealing fractures on the flow behaviour. Our results demonstrate that flow behaviour and hydraulic properties of such chemically altered fractures, i.e. chemical fractures, significantly depend on the evolving crystal geometries. Consequently, a novel equation to estimate hydraulic apertures is derived, which includes a geometry factor α for dissimilar crystal geometries (α = 2.5 for needle quartz and α = 1.0 for compact quartz). Finally, the outcome of our studies clearly demonstrate that nowadays novel experimental and numerical methods exist to precisely determine various fracture apertures improving our understanding of coupled processes on the fluid flow behaviour in fractured media.

Acknowledgements to Florian Amann, Christoph Butscher, Frieder Enzmann, Christoph Naab, Jens Oliver Schwarz and Daniel Vogler

How to cite: Blum, P., Hale, S., Cheng, C., Kling, T., Wendler, F., Pastewka, L., and Milsch, H.: Determination of hydraulic, mechanical and chemical fracture apertures , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13670, https://doi.org/10.5194/egusphere-egu2020-13670, 2020.

EGU2020-2937 | Displays | ERE6.3

A model for off-fault plastic poroelastic deformation and its effects on permeability

Bora Yalcin, Olaf Zielke, and P. Martin Mai

EGU2020-6920 | Displays | ERE6.3

Fictitious Domain methods for simulating thermo-hydro-mechanical processes in fractures

Cyrill von Planta, Maria G.C. Nestola, Daniel Vogler, Patrick Zulian, Nasibeh Hassanjanikhoshkroud, Xiaoqing Chen, Martin O. Saar, and Rolf Krause

Fictituous domain methods provide an promising way for simulating fluid structure interaction in fractures with complex geometries. The main characteristic of the method is that the solid and the fluid problem are simulated on different, non-matching meshes, with the solid being immersed into the fluid. The problems are coupled by L- projections, which transfer physical variables between the two computational domains and either the penalty, augmented Lagrangian or Lagrange multiplier method to represent the solid in the fluid. We show the evolution of our framework in the last three years, starting with benchmark problems such as Poiseulle flow, with successive extension to contact, fracture intersections and thermal coupling.

How to cite: von Planta, C., Nestola, M. G. C., Vogler, D., Zulian, P., Hassanjanikhoshkroud, N., Chen, X., Saar, M. O., and Krause, R.: Fictitious Domain methods for simulating thermo-hydro-mechanical processes in fractures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6920, https://doi.org/10.5194/egusphere-egu2020-6920, 2020.

EGU2020-7914 | Displays | ERE6.3

Analysis of flow and pressure data for the estimation of fracture generation and propagation – first model results from coupled hydromechanical experiments in COSC-1 borehole in deep crystalline rock, Åre, Sweden

Farzad Basirat, Chin-Fu Tsang, Alexandru Tatomir, Yves Guglielmi, Patrick Dobson, Paul Cook, Chris Juhlin, and Auli Niemi

Characterization of the coupled hydro-mechanical properties of rock fractures has become an increasingly important field of geosciences research, relevant for a number of key applications. Examples include analysis of enhanced geothermal systems, hydraulic fracturing operations, CO2 geological storage, nuclear waste disposal and mining operations. A newly developed technology that allows conducting advanced experimentation of the coupled HM processes in the field is the step-rate injection method for fracture in-situ properties (SIMFIP) by Guglielmi et al. (2014). The SIMFIP method is unique in that it measures simultaneously the time evolution of flow rate, pressure and 3D deformation of a packed off borehole interval.  

During June 2019 a field campaign was carried out in Åre, Sweden, where the SIMFIP was applied in the COSC-1 scientific borehole to estimate the fracturing and fracture propagation behavior during hydraulic stimulation in some previously well-characterized rock sections. Three intervals were investigated: an unfractured section (intact rock) at 485.2 m depth, a non-conductive steeply dipping fracture at 515.1 m depth, and a section with a gently dipping hydraulically conductive fracture at 504.5 m depth (Niemi et al., in prep.). 

As a first step for analyzing the results, this work aims to develop a simple hydrologic model for the interpretation of the collected pressure and flow data during different stages of the experiments. Modeling has been used to estimate the key parameters of the induced and propagated fractures such as the length, aperture and geometry, based on the pressure response during the water injection and abstraction steps. A numerical model based on COMSOL Multiphysics combining the fluid flow within the fracture and rock domains was developed and the permeability of fractures was defined by the well-known cubic law function of the local fracture aperture. The initial low injection-pressure data for the test interval without any fracture were used to find the parameters of the packed off borehole interval. Consequently, these parameters were used in the analysis of the case with a conducting fracture, as well as the case with a non-conducting fracture. Models in agreement with the observed pressures and injection flow rates could be defined for all the three cases, allowing parameters to be estimated for the length and aperture of the induced fractures in each case.

 

Guglielmi Y, Cappa F, Lançon H, Janowczyk JB, Rutqvist J, Tsang CF and Wang JSY. (2014) ISRM Suggested Method for Step-Rate Injection Method for Fracture In-Situ Properties (SIMFIP): Using a 3-Components Borehole Deformation Sensor. Rock Mech Rock Eng 47:303–311. https://doi.org/10.1007/s00603-013-0517-1

Niemi, Auli, Yves Guglielmi, Patrick Dobson, Paul Cook, Chris Juhlin, Chin-Fu Tsang, Benoit Dessirier, Alexandru Tatomir, Henning Lorenz, Farzad Basirat, Bjarne Almqvist, Emil Lundberg and Jan-Erik Rosberg 'Coupled hydro-mechanical experiments on fractures in deep crystalline rock at COSC-1 – Field test procedures and first results’. Manuscript under preparation, to be submitted to Hydrogeology Journal.

 

 

How to cite: Basirat, F., Tsang, C.-F., Tatomir, A., Guglielmi, Y., Dobson, P., Cook, P., Juhlin, C., and Niemi, A.: Analysis of flow and pressure data for the estimation of fracture generation and propagation – first model results from coupled hydromechanical experiments in COSC-1 borehole in deep crystalline rock, Åre, Sweden, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7914, https://doi.org/10.5194/egusphere-egu2020-7914, 2020.

Acoustic Emission (AE) based systems have been under development and used in this research at Fraunhofer – IEG to monitor, evaluate, and control conventional and novel drilling processes and their pertinent equipment used in geothermal applications. Moreover, new stimulation and high pressure (radial) jetting and drilling operations in deep geothermal reservoirs do heavily rely on such new technologies in order to be able to control them properly and thus, to generate an optimal connection between the main wellbore and the reservoir. As Service intervals and lifetime of machines have long been predicted and monitored via Acoustic Emission (AE) systems, and it is becoming a standard in numerous other industrial operations, AE is known as being a promising technique to be used for such monitoring purposes. AE monitoring is based on the detection and conversion of elastic waves into electrical signals, which are typically associated with a rapid release of localized stress-energy propagating within a given material. Thus, it is passive testing, logging, and analysis method to evaluate changes in the properties and behavior of machines and also mineral type materials such as rocks during operations. Such changes may be induced by drilling, jetting, or other drilling methods and being recorded, located, and evaluated via an AE system. This is the core of Fraunhofer – IEG’S new development, the AE based, so-called Multi-Sensor acoustic parameter analysis (MoUSE) as the primary control and monitoring mechanism during rock breaking, drilling, jetting, and stimulation. AE signals generated during jetting or bit-rock interaction are being monitored and analyzed extensively using novel numerical methods, based on sound analysis and engineering applications. The objective of this paper is to present an alternative approach for QA and QC during drilling, jetting, and stimulation operations based on AE waveforms generated during such continuous processes, including jetting and thermal drilling processes. Initial results of rock breaking tests, including mechanical, and non-contact drilling or jetting, will be presented.

How to cite: Jamali, S., Wittig, V., and Bracke, R.: Multi-Sensor Acoustic Parameter Analysis System for Monitoring and Evaluation of Deep Drilling, Jetting, and Stimulation Operations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7786, https://doi.org/10.5194/egusphere-egu2020-7786, 2020.

Enhanced Geothermal System (EGS) development requires an accurate fracture network characterization. The knowledge on the fracture network is fundamental for setting up numerical models to simulate the activated processes in hydraulic stimulation experiments. However, direct measurement of fracture network properties at great depth is limited to the data from exploration wells. Geophysical logging techniques and continuous coring, if available, provide the location and orientation of fractures that intersect the wellbore. The statistical parameters derived from borehole datasets (either from image logs or cores) constrain stochastic realizations of the rock mass, known as Discrete Fracture Network (DFN) models. However, accurate parametrization of DFN models requires sufficient knowledge on the depth-dependent spatial distribution of fractures in the earth’s crust.

This analysis includes a unique collection of fracture datasets from six deep (i.e. 2-5 km depth) boreholes drilled into crystalline basement rocks at the same tectonic settings. All the wells were drilled in the Upper Rhine Graben in Soultz-sous-Forêts Enhanced Geothermal System, France, except the well that was drilled in Basel geothermal project, Switzerland. The datasets included both borehole image logs and core samples, which have a higher resolution. Two-point correlation function was selected to characterize the power-law scaling of fracture patterns. The correlation dimension of spatial patterns showed no systematic variations with depth at one standard deviation level of uncertainty in moving windows of sufficient number of fractures along any of the boreholes. This implies that a single correlation dimension is sufficient to address the global scaling properties of the fractures in crystalline rocks. One could also anticipate the spatial distribution of deeper reservoir conditions from shallower datasets. On the contrary, the fracture density showed some variations with depth that are sometimes consistent with changes in lithology and geological settings at the time of fracture formation.

How to cite: Afshari Moein, M. J.: Depth-dependent analysis of fracture patterns inferred from image logs and cores in crystalline rocks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8987, https://doi.org/10.5194/egusphere-egu2020-8987, 2020.

EGU2020-20127 | Displays | ERE6.3

Preliminary results from interdisciplinary fault characterization in the Bedretto Underground Laboratory

Alexis Shakas, Hannes Krietsch, Marian Hertrich, Nima Gholizadeh, Katrin Plenkers, Hansruedi Maurer, Matthias Meier, Simon Loew, Morteza Nejati, Rebecca Hochreutener, Xiaodong Ma, Stefan Wiemer, Thomas Driesner, Domenico Giardini, Francisco Serbeto, Raymi Castilla, and Peter Meier

Engineered Geothermal Systems (EGS) are gaining increasing popularity as a source of renewable energy without significant CO2 emissions. Fractured crystalline rock masses offer a promising environment for exploitation of geothermal energy. In such a setting, fractures and faults are the main conduits for fluid flow and heat transport. In-situ fracture permeabilities are usually too low at depths where rock mass temperatures are sufficiently high for geothermal energy production. Therefore, a suitable heat exchanger needs to be engineered by hydraulic stimulations. A proper in-situ characterization of the fracture geometry and hydro-mechanical properties is of primary importance for the design of the stimulation operations. This is often the most challenging task, since the majority of the fractures in the reservoir are usually inaccessible for direct characterization.

 

The Bedretto Underground Laboratory for Geosciences (BULG) provides a novel and unique environment to study EGS-related processes, such as seismo-hydro-mechanical fault zone response during hydraulic stimulation and subsequent fluid circulation experiments. The laboratory is hosted in an access tunnel from the Bedretto Valley in the Southern Swiss Alps to a railway tunnel from the Matterhorn-Gotthard-Bahn. The overburden of more than 1000 m above the BULG provides conditions that are approaching those of realistic EGS systems. For the rock mass characterization, three boreholes were drilled perpendicular to tunnel axis with lengths ranging from 190 m to 300 m.

 

We present first data sets from a variety of methodologies, ranging from hydrological tests to geophysical borehole- and remote-imaging. The complementary nature of these data sets allows us to construct a preliminary three dimensional geological model. Notably, the individual measurements yielded information over a multitude of scales, ranging from millimeter-scale core-log information to decameter scale low-frequency Ground Penetrating Radar measurements. Such a wide range of scales is critical for the characterization of EGS reservoirs. The most prominent feature found is a large-scale fracture zone that extends across the entire investigation volume. This fracture zone will be the target for upcoming stimulation experiments.

How to cite: Shakas, A., Krietsch, H., Hertrich, M., Gholizadeh, N., Plenkers, K., Maurer, H., Meier, M., Loew, S., Nejati, M., Hochreutener, R., Ma, X., Wiemer, S., Driesner, T., Giardini, D., Serbeto, F., Castilla, R., and Meier, P.: Preliminary results from interdisciplinary fault characterization in the Bedretto Underground Laboratory, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20127, https://doi.org/10.5194/egusphere-egu2020-20127, 2020.

EGU2020-2950 | Displays | ERE6.3

Clustering and Connectivity of Fractal-Fracture Networks: Are they related?

Ajay Kumar Sahu and Ankur Roy

It well known that fracture networks display self-similarity in many cases and the connectivity and flow behavior of such networks are influenced by their respective fractal dimensions. One of the authors have previously implemented the concept of lacunarity, a parameter that quantifies spatial clustering, to demonstrate that a set of 7 nested natural fracture maps belonging to a single fractal system, but different visual appearances have different clustering attributes. Any scale-dependency in the clustering of fractures will also likely have significant implications for flow processes that depend upon fracture connectivity. It is therefore important to address the question as to whether the fractal dimension serves as a reasonable proxy  for the connectivity of a fractal-fracture network or is it the lacunarity parameter that may be used instead. The present study attempts to address this issue by studying the clustering behavior (lacunarity) and connectivity of fractal-fracture patterns. We compare the set of 7 nested fracture maps mentioned earlier which belong to a single fractal system, in terms of their lacunarity and connectivity values. The results indicate that while the maps that have the same fractal dimension have almost similar connectivity values, there exist subtle differences such that both the connectivity and clustering change systematically with the scale at which the networks are mapped. It is further noted that there appears to be an exact correlation between clustering and connectivity values. Therefore, it may be concluded that rather than fractal dimension, it is the lacunarity or scale-dependent clustering attribute that control connectivity in fracture networks.

How to cite: Sahu, A. K. and Roy, A.: Clustering and Connectivity of Fractal-Fracture Networks: Are they related?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2950, https://doi.org/10.5194/egusphere-egu2020-2950, 2020.

EGU2020-5157 | Displays | ERE6.3

A fast and robust approach for simulating the pressure diffusion in three-dimensional discrete fracture networks applied to inversion problems

Lisa Maria Ringel, Márk Somogyvári, Mohammadreza Jalali, and Peter Bayer

This study is aimed at the characterization of discrete fracture networks (DFN) by a transdimensional inversion methodology. It has been demonstrated that the reversible-jump Markov chain Monte Carlo (rjMCMC) is suitable for the inversion of two-dimensional (2D) DFNs. Based on given statistical information and measured data, the algorithm identifies the main characteristics of a DFN correctly.

For this reason, the method will be extended to the inversion of three-dimensional (3D) DFNs which allows more realistic examples. Two main difficulties arise here. First, further constraints have to be defined to limit the number of unknowns due to the high dimensionality of the inversion problem. Second, the forward modelling is a restricting factor concerning the computational costs and the robustness of the iteration. The assumptions made to simplify the governing fluid equations are to be evaluated and the resulting limitations are presented, e.g. small Reynolds number, smooth fracture walls, impermeable rock matrix. Moreover, the errors caused by the numerical solution of the partial differential equation are estimated to verify the correctness of the implementation.

How to cite: Ringel, L. M., Somogyvári, M., Jalali, M., and Bayer, P.: A fast and robust approach for simulating the pressure diffusion in three-dimensional discrete fracture networks applied to inversion problems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5157, https://doi.org/10.5194/egusphere-egu2020-5157, 2020.

EGU2020-6136 | Displays | ERE6.3

Can stationary cnoidal waves explain periodic deformation bands in porous sandstone?

Liz Elphick, Christoph Schrank, Adelina Lv, and Klaus Regenauer-Lieb

Deformation bands are sub-seismic brittle structures found in granular materials. These structures exhibit two spatial distributions: [1] non-linear decay of spacing associated with the damage zone of a fault, and [2] periodic, constant spacing not associated with faults. Periodically spaced deformation bands are of interest as they can be pervasive through porous (>5% φ) formations and are known to impact fluid flow. Bands can act as conduits or barriers to fluid flow and are commonly identified in petroleum reservoirs. An understanding of the factors controlling their distribution is therefore of great importance.

Here, we test a novel mathematical theory postulating that material instabilities in solids with internal mass transfer associated with volumetric deformation are due to elastoviscoplastic p-waves termed cnoidal waves. The stationary cnoidal wave model for periodic compaction bands predicts that their spacing is controlled by important material properties: the permeability of the weak phase in the pores, the viscosity of the weak phase, and the inelastic volumetric viscosity (strength) of the solid grains. A semi-analytical parametric study of the dimensional non-linear governing equations yields a surprisingly simple scaling relationship, which requires testing in the field. Stronger units with higher permeability are predicted to exhibit a wider spacing between deformation bands.

We test the cnoidal-wave model on natural deformation bands from Castlepoint, North Island, New Zealand. These bands are hosted by Miocene turbidites of the Whakataki formation, which formed in tectonically controlled trench-slope basins associated with the onset of subduction of the Pacific plate beneath the Zealandian plate along the Hikurangi subduction margin. Adjacent sand- and siltstone beds exhibit significant differences in deformation band spacing. Spacing statistics derived from field mapping and laboratory measurements of host-rock permeability and strength are employed to test the scaling relation predicted by the cnoidal wave model. Inconsistencies between theoretical and observed spacing are discussed critically.

How to cite: Elphick, L., Schrank, C., Lv, A., and Regenauer-Lieb, K.: Can stationary cnoidal waves explain periodic deformation bands in porous sandstone?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6136, https://doi.org/10.5194/egusphere-egu2020-6136, 2020.

EGU2020-6751 | Displays | ERE6.3

Time-lapse monitoring of fractured rock response to hydraulic stimulation using pressure tomography

Márk Somogyvári and Mohammadreza Jalali

Hydraulic stimulation using high-pressure fluid injection has become the common technique for rock mass treatment in various industrial applications such oil & gas, mining and enhanced geothermal system (EGS) development. Hydraulic stimulation is associated with creation of new fractures or dilation of existing fractures that could alter the flow regime in the stimulated reservoir. In this context, it would be beneficiary to understand the dynamic response of the discrete fracture network (DFN) to the stimulation activities rather than comparison between the changes in injectivity and/or transmissivity.

In this work, a 2-D fully coupled hydro-mechanical model is developed to simulate the dynamic response of a fractured reservoir to hydraulic stimulation. The model calculates stresses, fracture fluid pressure and flow inside the fractures, and modifies the physical properties of the individual fractures given these values. All these alterations will be calculated and applied after each simulation timestep. The results of this synthetic modelling will be used to test the time-lapse pressure tomography approach.

Pressure tomography will be simulated at multiple timesteps, to capture the hydraulically active fractures within the system. The used tomographic interpretation will be based on the transdimensional DFN inversion, where model parametrization could change over time. With this methodology we can model the newly opened fractures by the stimulation.

The time-lapse inversion will use the result of the previous timestep as the initial solution for improved efficiency. We test the proposed methodology on outcrop based synthetic 2-D DFN models. The results could capture the changes of permeability (i.e. aperture) as a direct response to hydraulic stimulation.

How to cite: Somogyvári, M. and Jalali, M.: Time-lapse monitoring of fractured rock response to hydraulic stimulation using pressure tomography, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6751, https://doi.org/10.5194/egusphere-egu2020-6751, 2020.

Reliable predictions of the distribution of permeabilities on site scale are economically relevant in a wide range of geoscientific disciplines. Not only are predictions important for modeling hydrogeological conditions at site scale but also for using the underground safely and sustainably.

Scale dependent, different geological processes are influencing the distribution of hydrogeological properties. A dataset of about 5000 inflows from individual transmissive fractures draining to about 660 km of drifts and 57 km of boreholes has been compiled into depths of 2000 mbgs of the Variscan age German Ore Mountains (Erzgebirge/Krušné hory). Fracture closure with increasing depth is a main process controlling the distribution of transmissivities. Additionally, orientation, age and mode of fault zones exert a major control on the local distribution of inflows. These factors are locally overprinted by with the presence of contact metamorphic aureoles around Variscan granitic intrusions as seen from transmissivity reversals with depth. However, as seen from a decreasing trend of mean log hydraulic conductivity and permeability, the contact metamorphism exerts minor control on the rock mass hydrology with depth than the decreasing secondary porosity provided by fractures.

These findings are in accordance with results deduced from a worldwide permeability compilation of about 30000 single in-situ permeability measurements to depths of 2000 mbgs. Geological influences on the distribution have been analyzed on permeability-depth relationships using log-log regressions. Depth is generally the most important geological factor, resulting in a permeability decrease of three to four orders of magnitude in the investigated depth range. Beside depth, most influential factors are the long-term tectono-geological history described by geological province which locally is overprinted by current seismotectonic activity as determined by peak ground acceleration. Although petrography might be of local importance, only a low impact has been observed for the global dataset, besides lithologies allowing for karstification.

In summary, the multi-variate analysis of the datasets has improved our generic understanding of the distribution of hydrogeological properties and provides a basis to model hydrogeological processes in fractured crystalline rocks.

How to cite: Achtziger-Zupancic, P. and Loew, S.: Geological Processes to Consider for Modeling the Distribution of Hydrogeological Properties in Fractured Crystalline Rocks on a Site Scale, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10913, https://doi.org/10.5194/egusphere-egu2020-10913, 2020.

EGU2020-7089 | Displays | ERE6.3

The strength of layered siliciclastic fault rocks as a function of composition and structure

Michael Kettermann, Volker Schuller, Andras Zamolyi, and Mira Persaud

Normal faults are common in sedimentary basins and often associated with reservoirs in interbedded sands and clays. Fault rocks therefore also consist of some mixture of sand and clay. Outcrop studies have shown, that these fault rocks can occur as homogeneous mixtures, (multiple) parallel layers of sand and clay without intense grain-scale mixing, or complex structures with brittle clasts of one material embedded in a ductile sheared matrix of the other. Both, the composition and the structure of the fault rock affect its the overall frictional strength at any given position.

The strength of faults in sedimentary basins is crucial information when producing fluids from faulted reservoirs in critically stressed conditions. Increasing pore pressure during injection phases bears the risk of fault reactivation. To minimize the risk of reactivation while maximizing the recovery, our goal is to improve the prediction of fault friction. The predicted friction coefficient can then be used in dynamic reservoir models to calculate the maximum allowed pore pressure increase. 

From literature we compile the friction coefficients for various homogeneous sand-clay mixtures at different effective normal stresses, measured in laboratory tests. The resulting function shows a linear increase of the friction coefficient with increasing sand content, while normal stress only shows an effect for stresses larger than expected at reservoir conditions. We can now use this function to predict the friction coefficient for any given homogeneous sand-clay mixture.

However, fault rocks are often not homogeneous mixtures. To gain insights into natural fault rock compositions, we investigate field and sample data in 2D and 3D from outcrops in northwest Borneo/Malaysia. These show the complex structure of fault rocks on various scales for faults with displacements from cm to decameter range.

In exploration and production workflows, commonly algorithms such as the shale gouge ratio are applied to predict the average volume of clay (Vclay) in the fault rock, based on the amount of clay in the unfaulted rock and the displacement. The average Vclay is then loosely correlated to a friction coefficient, often proprietary to the used software packages. We propose that the structure of the fault rock, i.e. the distribution of clay and sand, affects the frictional properties estimated for the average Vclay.

We use discrete element numerical simulations to study the effect of complex fault rock structures on the fault friction coefficient. We reproduce natural structures from outcrop and sample data and calibrate the mechanical properties of the individual components in the model to fit the natural prototype. In direct-shear tests we then measure the friction coefficient of the entire modelled fault rock. Preliminary results show a discrepancy between the friction coefficient of a homogeneous sand-clay mixture and a more complex geometry with the same clay volume. This suggests errors in currently used approaches that are solely based on Vclay.

How to cite: Kettermann, M., Schuller, V., Zamolyi, A., and Persaud, M.: The strength of layered siliciclastic fault rocks as a function of composition and structure, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7089, https://doi.org/10.5194/egusphere-egu2020-7089, 2020.

EGU2020-12857 | Displays | ERE6.3

Evaluating the fracture morphology of shale specimen by the means of AE power spectrum characteristics

Qiang Xie, Yuxin Ban, Xiang Fu, and Chunbo He

Quantitative evaluation of the fracture morphology of shale is an essential prerequisite for assessing the complexity of hydraulic fracturing fracture networks during shale gas exploitation. Brazilian tests coupled with digital image correlation and acoustic emission technique were conducted on black shale in Sichuan Basin in China, the corresponding relationships between the characteristics of the frequency band of acoustic emission power spectra and the micro-damage mechanism of rock specimens were established, and the fracture morphology was quantitatively evaluated. The bedding layer leads to the differences in power spectra characteristics, micro-damage mechanism and fracture morphology of shale. The tension and shear failure of shale matrix induce high-frequency acoustic emission signals, and the tension and shear failure of shale bedding induce low-frequency acoustic emission signals. With the increase of the angle between the bedding layer and loading direction, the dominant frequency and secondary dominant frequency gradually diffuse from low-frequency band to high-frequency band, and the quantitative ratio of high frequency to low frequency  H:L gradually increases. The H:L  of 0° shale specimen is 4.28%: 95.72%, and the fracture is a straight line in shape. The H:L of 30° and 60° shale specimens are 15.89%: 84.11% and 36.93%: 63.07% respectively, and their fractures are arched in shape. The H:L of 90° specimen is 93.85%: 6.15%, and the fracture is composited arc-straight line in shape. The results can provide references for analyzing micro-seismic data in situ, and provide a theoretical basis for controlling fracture trajectory in hydraulic fracturing in shale reservoirs.

How to cite: Xie, Q., Ban, Y., Fu, X., and He, C.: Evaluating the fracture morphology of shale specimen by the means of AE power spectrum characteristics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12857, https://doi.org/10.5194/egusphere-egu2020-12857, 2020.

EGU2020-16033 | Displays | ERE6.3

Construction of 3D Discrete Fracture Network Model using Structural and Hydrogeological Data

Mohammadreza Jalali, Zhen Fang, and Pooya Hamdi

The presence of fractures and discontinuities in the intact rock affects the hydraulic, thermal, chemical and mechanical behavior of the underground structures. Various techniques have been developed to provide information on the spatial distribution of these complex features. LIDAR, for instance, could provide a 2D fracture network model of the outcrop, Geophysical borehole logs such as OPTV and ATV can be used to investigate 1D geometrical data (i.e. dip and dip direction, aperture) of the intersected fractures, and seismic survey can mainly offer a large structure distribution of the deep structures. The ability to combine all the existing data collected from various resources and different scales to construct a 3D discrete fracture network (DFN) model of the rock mass allows to adequately represent the physical behavior of the interested subsurface structure.

In this study, an effort on the construction of such a 3D DFN model is carried out via combination of various structural and hydrogeological data collected in fractured crystalline rock. During the pre-characterization phase of the In-situ Stimulation and Circulation (ISC) experiment [Amann et al., 2018] at the Grimsel Test Site (GTS) in central Switzerland, a comprehensive characterization campaign was carried out to better understand the hydromechanical characteristics of the existing structures. The collected multiscale and multidisciplinary data such as OPTV, ATV, hydraulic packer testing and solute tracer tests [Jalali et al., 2018; Krietsch et al., 2018] are combined, analyzed and interpreted to form a combined stochastic and deterministic DFN model using the FracMan software [Golder Associates, 2017]. For further validation of the model, the results from in-situ hydraulic tests are used to compare the simulated and measured hydraulic responses, allowing to evaluate whether the simulated model could reasonably represent the characteristics of the fracture network in the ISC experiment.

 

References

  • Amann, F., Gischig, V., Evans, K., Doetsch, J., Jalali, M., Valley, B., Krietsch, H., Dutler, N., Villiger, L., Brixel, B., Klepikova, M., Kittilä, A., Madonna, C., Wiemer, S., Saar, M.O., Loew, S., Driesner, T., Maurer, H., Giardini, D., 2018. The seismo-hydromechanical behavior during deep geothermal reservoir stimulations: open questions tackled in a decameter-scale in situ stimulation experiment. Solid Earth 9, 115–137.
  • Golder Associates, 2017. FracMan User Documentation.  Golder Associates Inc, Redmond WA.
  • Krietsch, H., Doetsch, J., Dutler, N., Jalali, M., Gischig, V., Loew, S., Amann, F., 2018. Comprehensive geological dataset describing a crystalline rock mass for hydraulic stimulation experiments. Scientific Data 5, 180269.
  • Jalali, M., Klepikova, M., Doetsch, J., Krietsch, H., Brixel, B., Dutler, N., Gischig, V., Amann, F., 2018. A Multi-Scale Approach to Identify and Characterize the Preferential Flow Paths of a Fractured Crystalline Rock. Presented at the 2nd International Discrete Fracture Network Engineering Conference, American Rock Mechanics Association.

How to cite: Jalali, M., Fang, Z., and Hamdi, P.: Construction of 3D Discrete Fracture Network Model using Structural and Hydrogeological Data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16033, https://doi.org/10.5194/egusphere-egu2020-16033, 2020.

EGU2020-18745 | Displays | ERE6.3

Tomographical field investigation of hydraulic properties of a fractured aquifer using active thermal tracer testing

Quan Liu, Rui Hu, Pengxiang Qiu, Ran Tao, Huichen Yang, Yixuan Xing, and Thomas Ptak

Compared to porous media, fractured aquifers are generally characterized by a more pronounced hydraulic heterogeneity. To describe hydraulic properties of fractured subsurface, investigation methods such as hydraulic tests, tracer tests and hydrogeophysical tests have been widely used. In recent years, thermal tracer tests are obtaining more attention because thermal response signals can be easily and economically obtained at a high resolution, e.g. using distributed temperature sensing (DTS) systems. Some studies have even employed the travel-time-based thermal tracer tomography (TTT) to reconstruct the aquifer heterogeneity (Somogyvári M. et al., 2016; Somogyvári M. and Bayer P., 2017). In this study, we further develop and apply the TTT method for a field scale investigation of the hydraulic properties at a geothermal test site in Göttingen, Germany, equipped with five instrumented experimental wells.

Presently, using travel-time-based thermal tracer tomography to describe the hydraulic connectivity or conductivity is limited to the condition that the heat transfer must be convection dominated. Thus, the field experiments have to be divided into two steps. A full length well warm water injection test is firstly conducted to obtain information about the basic hydrogeological conditions, such as the fracture insertion depth and the connectivity between the wells. Subsequently, four multilevel thermal tracer tests are performed. The temperature changes in all five wells are recorded using a DTS system. Finally, based on the travel-time-based inversion method, the hydraulic conductivity distribution of the fractured aquifer can be obtained.

Preliminary test results showed that the orientation of transmissive fractures is mainly along the E-W direction at our test site. Given the good hydraulic connectivity, the first thermal tracer tomographical tests in a fractured aquifer were performed between two wells positioned along this direction. As next, we will work on the reconstruction of the fracture distribution between those two wells.

How to cite: Liu, Q., Hu, R., Qiu, P., Tao, R., Yang, H., Xing, Y., and Ptak, T.: Tomographical field investigation of hydraulic properties of a fractured aquifer using active thermal tracer testing, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18745, https://doi.org/10.5194/egusphere-egu2020-18745, 2020.

EGU2020-21671 | Displays | ERE6.3

Groundwater flow at the Rock Garden test site

Andreas Englert, Wolfgang Gossel, and Peter Bayer

Understanding of subsurface flow and transport is of major interest supporting optimal design for several societal relevant technologies, such as waste disposals, geothermal or groundwater production facilities. To advance measurement and modeling techniques and refine them for practical applications, we develop the fractured aquifer test site Rock Garden at the Martin-Luther University Halle.

 

The Rock Garden test site is situated beneath the courtyard of the Faculty of Natural Sciences III and is 60 m x 60 m in size. Fractured Rotliegend series of konglomerates, sand- and siltstones are investigated at the site by 6 drillings. A central borehole (B3) is 40 m in depth and developed as an open borehole between 15 m – 40 m below surface. Five boreholes are developed as groundwater observation wells of about 20 m depth and are equipped with filterscreens between 10 m - 20 m below surface. Natural groundwater levels are on average about 3 m below surface and vary about 0,5 m around this value.

 

A first pumping test in B3 unraveled hydraulic connection to all of the five surrounding boreholes. The effective transmissivities are of the order of 10-5 m2/s and storativities are of the order 10-3. To understand hydraulically active fractures or fracture zones and their connection to the rock matrix at the Rock Garden site, we plan to performed a first flowmeter experiment in well B3 under natural and pumping conditions. Finally we plan to characterize these fractured zones in detail performing hydraulic and tracer tomography at the Rock Garden test site in the near future.

How to cite: Englert, A., Gossel, W., and Bayer, P.: Groundwater flow at the Rock Garden test site, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21671, https://doi.org/10.5194/egusphere-egu2020-21671, 2020.

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