ERE2.4 | Geothermal systems: Exploration, exploitation and monitoring of geothermal resources
EDI
Geothermal systems: Exploration, exploitation and monitoring of geothermal resources
Convener: Domenico Montanari | Co-conveners: Alper Baba, Paromita Deb, Kai LiECSECS, Pilar Sánchez Sánchez-PastorECSECS, Sin-Mei WuECSECS
Orals
| Thu, 27 Apr, 08:30–12:25 (CEST)
 
Room -2.16
Posters on site
| Attendance Thu, 27 Apr, 16:15–18:00 (CEST)
 
Hall X5
Posters virtual
| Attendance Thu, 27 Apr, 16:15–18:00 (CEST)
 
vHall ERE
Orals |
Thu, 08:30
Thu, 16:15
Thu, 16:15
Clean-Energy Transition is a central concept to EU energy and climate policies, and in this context the need for geothermal resources utilization is accelerating. Geothermal energy can be extracted from different, often complex geological settings (e.g., fractured crystalline rock, magmatic systems, or sedimentary basins). Current advancements also target unconventional systems (e.g., enhanced geothermal systems, super-hot, pressurized and co-produced, super-critical systems) besides conventional hydrothermal systems. Optimizing investments leads also to the development of associated resources such as lithium, rare earths and hydrogen. This requires a joint effort for understanding and modelling geological systems that are specific to each resource. Sustainable use of geothermal resources requires an advanced understanding of the properties of the entire system at every stage of geothermal field development, including but not limited to geophysical properties, thermo-/petro-physical conditions, fluid composition; structural and hydrological features; and engineering considerations. The main challenges faced are, among others, exploration of blind systems, reservoir stimulation, environmental concerns, induced seismicity, multiphase fluid and scaling processes, monitoring.
The integration of analogue field studies with real-life production data, from industrial as well as research sites, and with numerical models, is a hot topic worldwide. We aim to gather field, laboratory and numerical experts who focus their research on geothermal sites, to stimulate discussion in this multidisciplinary applied research field. We encourage contributions from experts from a broad range of disciplines such as (hydro)geologists, geochemists, (geo)physicists, surface and subsurface engineers. The aim of this session is to gather inputs focusing on the interplay between different approaches. We welcome contributions from different research areas ranging from field data collection and analysis to laboratory experiments (e.g., geophysical surveys, structural characterization, geomechanical, geochemical experiments), and from data management and organization to numerical modeling.

Orals: Thu, 27 Apr | Room -2.16

Chairpersons: Pilar Sánchez Sánchez-Pastor, Paromita Deb, Kai Li
08:30–08:40
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EGU23-407
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ECS
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Virtual presentation
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Val Maverick Abecia, Sonia Salah, Mirela Vasile, Ben Laenen, Simona Regenspurg, and Valérie Cappuyns

Low enthalpy geothermal energy utilization is currently of great interest in Europe as a clean and sustainable alternative energy source, due to its potential to meet the demand for both electricity and space-heating. The increased interest presently accelerates research and development particularly for deep-seated, hot sedimentary aquifers all over Europe. Among the least understood aspects is the presence of naturally-occurring radionuclides (NORs)  such as 226Ra, 228Ra, 222Rn, 210Po, and 210Pb and the underlying geochemical processes and constraints affecting their mobility. This study aims to characterize natural organic matter (NOM) and synthetic scaling and corrosion inhibitors and their by-products as a first step to determine their role in the partitioning and mobility of these radionuclides. A two-step dead-end filtration at 0.45 and 0.22 μm pore sizes was conducted for the hypersaline brine from the production and injection wells (TDS= 100-270 g/L) of the Balmatt geothermal site in an anoxic environment, to initially determine the total organic carbon (TOC) and radiochemistry per filtrate fraction. The TOC content of filter residues was measured by combustion catalytic oxidation method, while the filtrates were excluded due to their known low organic carbon content yet hypersaline nature, requiring large dilution factors. UV-VIS spectrophotometry of all brine filtrates using various wavelengths (i.e. 204, 220, 254, 280, 365, 400, 436, 665 nm) shows very low absorbance ranges (e.g. A254 = 0.03-0.07,  A280 = 0.01-0.05), corroborating with  low organic carbon contents. On the other hand, the absorbance values of the scaling and corrosion inhibitors are higher (e.g. A254 = 6-10 , A280= 5-8)  correlating to higher TOCs of 64 mg C/L and 180 mg C/L, respectively. This suggests that the synthetic inhibitors may be an additional source of organic compounds possibly affecting the partitioning and mobility of NORs. Initial results of the radiochemical analyses by liquid scintillation and alpha spectrometry also show that total activity of 210Pb and 210Po are relatively higher at the production side (210Pb =0.20 Bq/L, 210Po=37 mBq/L) than the injection side (210Pb <0.09 Bq/L, 210Po=0.9 mBq/L), possibly suggesting their fractionation from the fluid to the known mineral scales such as galena. Other NORs measured using gamma spectroscopy indicate high activities of 222Rn (12.2 Bq/L), 226Ra (124-136 Bq/L) and 228Ra (9.3 Bq/L). In the future, leaching experiments will be conducted using reservoir rock cuttings from the geothermal wells to possibly distinguish between NOMs and synthetic inhibitor by-products. Size exclusion chromatography per filter fraction using a tangential flow setup will also be conducted to further characterize the organic matter. Reverse osmosis and solid phase separation are being considered in sample preparation to resolve the issue of low TOC but very high salt content of the fluids of the Balmatt geothermal system.

How to cite: Abecia, V. M., Salah, S., Vasile, M., Laenen, B., Regenspurg, S., and Cappuyns, V.: Characterization of natural and synthetic organic matter and naturally-occurring radionuclides in the hypersaline geothermal fluids of Balmatt site, Mol, Belgium: preliminary results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-407, https://doi.org/10.5194/egusphere-egu23-407, 2023.

08:40–08:50
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EGU23-8583
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ECS
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On-site presentation
Jasmin Grifka, Mathias Nehler, Tobias Licha, and Thomas Heinze

Declining permeability of geothermal reservoirs due to fines migration is often considered with regard to existing fines like clay particles that are mobilized. However, fines are also generated due to dissolution and chemical stimulation techniques can induce the generation of fines. For near-wellbore regions, this is uncritical as fines can be extracted after stimulation using cleaning lifts. With the aim of replacing hydraulic stimulations for enhanced geothermal systems by a reservoir-wide chemical stimulation, the penetration depth of the acids needs to be substantially increased. However, cleaning lifts to remove fines are no longer possible in greater distance from the wellbore, so alternative strategies are required.

Flow-through experiments with citric acid on dolostone were used to investigate the dependence of fines generation on the reaction conditions. For all dissolution regimes over a range of different Damköhler numbers, fines were generated and could greatly reduce the permeability of the rock samples. Only when large pathways were created by the dissolution process, the generated fines were transported out of the major pathways as well as dissolved therein, thus not interfering with the increase of permeability due to dissolution. The results highlight the great challenges for reservoir-wide chemical stimulations techniques using retarded acid systems, but also indicate possible solutions.

How to cite: Grifka, J., Nehler, M., Licha, T., and Heinze, T.: Fines migration as a challenge for reservoir-wide chemical stimulation using retarded acid systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8583, https://doi.org/10.5194/egusphere-egu23-8583, 2023.

08:50–09:00
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EGU23-10151
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ECS
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On-site presentation
Alba Martín-Lorenzo, Nemesio M. Pérez, Gladys V. Melián, Fátima Rodríguez, Cecilia Amonte, María Asensio-Ramos, Pedro A. Hernández, and Eleazar Padrón

The most common types of survey in known geothermal areas are water and gas sampling of natural discharges. However, where wáter and gas discharge features are few and where the extent of the field is not known, soil and soil-gas surveys can prove useful. These surveys can identify areas in a field that are permeable and potential upflow or boiling zones. They can also outline the boundaries of a geothermal system, often in conjunction with geophysical surveys to provide more comprehensive understanding, especially when geophysical data is difficult to interpret. For all of the above, a soil and soil-gas survey for geothermal exploration had been carried out at Cumbre Vieja volcano that is characterized by neither having visible manifestations of volcanic gases nor zones of hydrothermal alteration on its surface. We have divided the soil and soil-gas survey for geotermal exploration into four categories based on the number of sampling sites per square kilometer: 1) Regional exploration survey (1 sampling site/km2), 2) Regular exploration survey (about 5 sample sites/km2), 3) Detailed I exploration survey (between 10 and 100 sampling sites/km2) and 4) Detailed II exploration survey (more than 500 sampling sites/km2). We have classified our soil and soil-gas survey for geothermal exploration at Cumbre Vieja volcano as a regular exploration survey due to the fact that 1200 observation or measurement points were selected for its 220 km2 area, resulting in approximately 5.5 sampling sites per km2. Similar soil gas surveys had been performed in other study áreas of the Canarian archipelago (Rodríguez et al. 2021). At every sampling site, we performed in-situ measurements of soil CO2 efflux and 222Rn activity in the soil gas atmosphere. In addition, soil gas samples were collected at a depth of 40 cm for further chemical and isotopic analysis in our geochem lab. Simultaneously with the soil gas survey, soil samples were collected from the base of the B Horizon-Subsoil (30–50 cm) which were subsequently dried and sieved (80 mesh) for subsequent leaching in order to analyze those volátiles (Hg0, As, B and NH3) of interest that were fixed in the organic-clay fraction of the soils. Some preliminary results of this soil and soil-gas survey for geothermal exploration at Cumbre Vieja are presented.

Rodríguez F., Pérez N. M., Melián G. V., Padrón E., Hernández P. A., Asensio-Ramos M., Padilla G. D., Barrancos J. and D’Auria L. (2021). Exploration of deep-seated geothermal reservoirs in the Canary Islands by means of soil CO2 degassing surveys. Renewable Energy, https://doi.org/10.1016/j.renene.2020.09.065

How to cite: Martín-Lorenzo, A., Pérez, N. M., Melián, G. V., Rodríguez, F., Amonte, C., Asensio-Ramos, M., Hernández, P. A., and Padrón, E.: Soil and soil-gas surveys for geothermal exploration at Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10151, https://doi.org/10.5194/egusphere-egu23-10151, 2023.

09:00–09:10
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EGU23-17482
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ECS
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On-site presentation
Lorena Alejandra Bello Rujana, Hartwig von Hartmann, Inga Moeck, and Matthias Franz

The application of machine learning (ML) for reservoir characterization and prospect identification in seismic data is becoming standard practice in the exploration industry. This technique has proven useful in identifying patterns in the data that might be overlooked by the interpreter. In addition, it improve reservoir predictions and characterization at a lower computational cost.

In this study, we analyze the fluvio-deltaic seismic facies of the Upper Triassic Exter Formation in the North German Basin. For this purpose, we applied seismic attributes and an unsupervised machine learning algorithm based on waveform segmentation of seismic amplitude data. Furthermore, to evaluate the evolution of deltaic complexes, we implemented the stratal slicing technique through the resulting waveform segmentation and the generated attributes volumes.

The study resulted in the delineation of a number of fluvial architectural elements in the study area, i.e. lateral shifting of individual channels contributing to the formation of channel belt reservoirs within the Rhaetian Deltaic System.

These results contribute significantly to reducing the risk of geothermal exploration in the North German Basin by proposing for the first time a way to improve the prediction of Rhaetian reservoirs on a local scale based on seismic methods.

How to cite: Bello Rujana, L. A., von Hartmann, H., Moeck, I., and Franz, M.: Identification of fluvio-deltaic facies based on 3D-seismic attributes analysis and unsupervised machine learning techniques: strategy to reduce geothermal exploration risk in the North German Basin., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17482, https://doi.org/10.5194/egusphere-egu23-17482, 2023.

09:10–09:20
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EGU23-14710
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ECS
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On-site presentation
Po-Li Su, Hsin-Hua Huang, Cheng-Horng Lin, and Jian-Cheng Lee

The Ilan Plain in northeastern Taiwan located at the southern termination of the Okinawa Trough, which is formed by the back-arc extension of the Ryukyu subduction zone. Owing to this extensional tectonic setting, the Ilan Plain shows distributed hot springs with high geothermal gradient in several places, such as the Chingshui, Jiaoxi, Longde-Lize and Hongchailin areas. These are potential locations for geothermal exploration which require a thorough investigation to understand their geothermal system and to evaluate their potential in geothermal power generation. Seismic velocity provides key information to determine properties of a geothermal system including the distribution of fluids, fractures, and porosity. This study obtained seismic velocity images of the Ilan Plain and the surrounding area by joint inversion of body wave travel times of local earthquakes and Rayleigh wave phase velocities from ambient noise correlations recorded by a temporary dense geophone array in the Ilan Plain and the Formosa Array in northeastern Taiwan. The joint inversion takes advantage of the complementary sensitivities of both data types to better constrain both shallow and deep structures. In addition, we also lift the flat earth surface assumption commonly assumed in the surface wave tomography to avoid possible biased velocity structure due to topography by adapting the surface wave sensitivity kernel to the surface topography in the inversion. The obtained image at the 1-km depth shows low Vp and Vs corresponding to unconsolidated Quaternary sediments. The deeper images at 2- to 5-km depths show a low-velocity corridor extending from the Guishan volcanic island northeastern offshore to the southwest corner of the Ilan Plain, implying that the heat source of the geothermal systems in the Ilan Plain may be related to magmatic intrusions of backarc rifting. Locally, in the shallow region of the Chingshui and Jiaoxi area and the deeper region of the Hongchailin and Longde-Lize area, the high Vp/Vs ratio with little increase in Vp and significant decrease in Vs could indicate a saturated rock with high porosity, based on the rock physics principles in geothermal environment summarized in previous study. The low Vp, Vs, and Vp/Vs ratio in the shallow region of the Hongchailin area could indicate vapor-rich high temperature environment. Our results demonstrate the potential of new seismic imaging integrating body- and surface-wave data for geothermal exploration.

How to cite: Su, P.-L., Huang, H.-H., Lin, C.-H., and Lee, J.-C.: High resolution Vp and Vs imaging for geothermal exploration in the Ilan Plain, northeastern Taiwan by joint inversion of body-wave and surface-wave data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14710, https://doi.org/10.5194/egusphere-egu23-14710, 2023.

09:20–09:30
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EGU23-10646
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On-site presentation
Rui Cao, Ji Dor, and Huiren Meng

The Qinghai-Tibet Plateau, located in the world-famous Mediterranean-Himalayan tropics, is the most intensely tectonically active region of the Cenozoic in mainland China. Accompanied with a large amount of hydrothermal activity and energy generation, this region had the greatest potential and concentration of high-temperature geothermal resources in mainland China. The Gudui geothermal field, located in the central Cone-oiga rift, is a shallow buried high-temperature geothermal field with the greatest power generation potential. In order to analyze the types and distribution characteristics of sinter and hydrothermal alteration, the favorable exploration direction and heat-controlling structure of Gudui geothermal field, the geothermal geological investigation, microscopic identification, and scanning electron microscope analysis were carried out. The hydrothermal alteration types, such as chloritization, silicification, kaolinization and carbonation, and sinters such as travertine, geyserite and sulphur, were identified. Three groups of faults were developed in the Gudui geothermal field with respect to the heat-controlling structure. The early EW faults are mostly reverse faults, and the later NE or NW secondary faults are mostly extensional faults as the main channels of geothermal fluid.The distribution of hydrothermal alteration is controlled by normal fault, of which alteration center is mainly located at the junctions of faults, and extends along the faults. An obvious hydrothermal alteration zonation was existed in the Gudui geothermal field, which extends from acidic alteration to weak acidic-neutral alteration, and the alteration center is mainly composed of extensively altered silicification or kaolinization zones. The distribution and intensity of hydrothermal alteration implies that the Bushonglanggu and Shagalanga geothermal display area have enormous resource potential. Therefore, geothermal exploration in Gudui geothermal field should focus on the Bushonglanggu and Shagalanga geothermal display area. with respect to hydrothermal deposition, the west area of Gudui geothermal field is dominated by travertine, and the east area is characterized by the coexistence of travertine and siliceous sinter. Furthermore, combined with the dynamic background of Qinghai-Tibet Plateau, an obvious coupling relationship exists between hydrothermal history and the uplift of Qinghai-Tibet Plateau during continent-continent collision and the activity of the Cone-oiga rift.

How to cite: Cao, R., Dor, J., and Meng, H.: Hydrothermal activity characteristics, types of hydrothermal alteration and exploration direction in Gudui high temperature geothermal field, Tibet, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10646, https://doi.org/10.5194/egusphere-egu23-10646, 2023.

09:30–09:40
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EGU23-11331
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ECS
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On-site presentation
Nicklas Ackermann, Alexander Jüstel, Michael Kettermann, Oliver Ritzmann, Gregor Bussmann, Carsten Lehmann, and Florian Wellmann

The Münsterland Cretaceous Basin with its underlying coal-bearing Paleozoic strata has become one of the prolific areas in North-Rhine Westphalia, Germany, to develop conventional geothermal systems. The presence and structural deformation of four potential calcareous and siliciclastic geothermal reservoirs within the basin (Upper Cretaceous carbonates) and the basement (Lower Carboniferous carbonates, Upper Devonian sandstones, Upper/Middle Devonian carbonates) are only known from sparsely distributed boreholes and crustal seismic data (DEKORP). We aim at reducing the geological uncertainties by interpreting and analyzing legacy data of the DEKORP project, and recently acquired 2D seismic data from the central Münsterland. In addition, information from former research and hydrocarbon wells, now intersecting the newly acquired surveys, were integrated to guide and verify the interpretation. Our investigations contribute to the already existing knowledge of the Variscan folding and spatial distribution of the potential geothermal reservoirs within and below the Münsterland Cretaceous Basin. Further, we show previously undescribed local inversion structures in the Cretaceous section caused likely by the reactivation of post-Variscan transtensional faults in the center of the basin. The seismic data exhibits anomalies which will be analyzed if they are indicating areas of increased porosities through structural deformation or the presence of migrated hydrocarbons in these regions. The latter would imply a structural connection between coal-bearing Carboniferous strata and porous reservoirs in the Upper Cretaceous via deep-reaching reactivated faults. The presence of fault zones that have evidently been vertically permeable on a geological time scale demonstrate possible fluid pathways for conventional geothermal systems. Such geothermal systems could be future targets for drilling to produce local renewable district heating for the city of Munster.  Therefore, further investigations such as in-situ tests through drillings are required to quantify the current permeability of these damage zones.

How to cite: Ackermann, N., Jüstel, A., Kettermann, M., Ritzmann, O., Bussmann, G., Lehmann, C., and Wellmann, F.: Insights on structural deformation within the Münsterland, Germany, from legacy and newly acquired 2D seismic data for the development of conventional geothermal systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11331, https://doi.org/10.5194/egusphere-egu23-11331, 2023.

09:40–09:50
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EGU23-13303
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ECS
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On-site presentation
Kathrin Behnen, Marian Hertrich, Hansruedi Maurer, and Alexis Shakas and the Bedretto-Team

The prior characterization of a reservoir volume as well as the monitoring of potential changes during heat extraction is highly important to ensure an economic and safe engineering and operation of a geothermal reservoir. While the use of active seismic measurements from the surface and in boreholes is commonly used to describe the seismic velocity field in the subsurface, its potential to analyze the seismic anisotropy is often neglected. We used active seismic crosshole measurements to analyze seismic anisotropy at the field scale to provide important information about the elastic properties and take advantage of this information for the analysis of the in-situ rock-physical conditions.

For the analysis of seismic anisotropy, a reliable data set is essential. We studied the sensitivity of the resulting anisotropy model to inaccuracies in the survey geometry by computing synthetic data and showed that inaccuracies of only a few degrees in dip and azimuth of the borehole orientation can significantly change the resulting anisotropy model of the volume. Especially the orientation of the symmetry axis used to describe a transverse isotropic model (TI) is highly sensible to source and receiver positions.

Beyond the analysis of the synthetic data, the focus of our study was on the exploitation of real measurement data. These data were recorded in a campaign in the Bedretto Underground Laboratory for Geosciences and Geoenergies (BULGG) in Ticino, Switzerland. The laboratory provides the opportunity to record crosshole data with high quality in a controlled environment. The geometry of the boreholes that we used allows a high coverage of ray path orientations which is crucial for the analysis of anisotropic wave propagation. The recorded data were used to create an anisotropy model of the subsurface based on a grid search and optimization algorithm, searching for both the optimized Thomsen parameters and the ideal orientation of the symmetry axis of the tilted TI model. The results give evidence of an ambient elastic anisotropy, while the host rock (Rotondo Granite) has proven negligible intrinsic anisotropy in previous laboratory measurements at sample scale. Further investigation will analyze the effect of the fracture inventory and ambient state of stress as potential controlling factors of the observed anisotropy. This relation can potentially help to monitor changes in the stress field during geothermal operations for a better hazard assessment.

How to cite: Behnen, K., Hertrich, M., Maurer, H., and Shakas, A. and the Bedretto-Team: Seismic anisotropy analysis based on synthetic and measured data for crystalline rock characterization, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13303, https://doi.org/10.5194/egusphere-egu23-13303, 2023.

09:50–10:00
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EGU23-12749
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ECS
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On-site presentation
Mrityunjay Singh, Claire Bossennec, Kristian Bär, John Reinecker, Robbie Bilsland, Chris Briggs, Lucy Cotton, Jon Gutmanis, Tony Bennet, Jörg Baumgärtner, Augusta Grand, Nils Recalde Lummer, Omair Rauf, Clément Baujard, Albert Genter, and Ingo Sass

To increase fluid flow and thus obtain higher heat production from a geothermal well, chemical stimulation can be performed in their open-hole sections. Through chemical stimulation, fracture zone permeability in the vicinity of the borehole can be enhanced which results in higher fluid connectivity from the well to the reservoir fracture network. To understand the chemical stimulation effect on fault zone permeability enhancement and pressure development, the Eden geothermal project acted as a demonstration site in the framework of the MEET project. The open-hole section of the Eden geothermal project was characterized based on drill cutting analysis, several borehole geophysical logs including (Spectral Gamma Ray, Caliper, Borehole Image, etc.) as well as hydraulic testing. These hydraulic injection tests were carried out from January to March 2022 in the form of several low injection tests, where fluid was injected in a series of flow rates ranging from 5 – 15 l/s. Furthermore, a chemical stimulation test was performed in August-September 2022 followed by another series of hydraulic injection and production tests until late November 2022 at flow rates of 5 – 12.5 l/s. Rock cuttings from the target zone (3940 m TVD) indicated up to 3% of calcite which is easily dissolvable by acids. Therefore, the chemical stimulation was primarily aimed to treat possible near-wellbore damage resulting from an LCM cementation carried out during the drilling of the well in 2021, prior to installing the production casing.

Especially at high temperatures, commonly employed HCl tends to treat only near wellbore regions and show high corrosivity against metal tubular. To counteract such drawbacks, the strong organic acid system SSB-007 was used for chemical stimulation [1]. The two hydraulic injection test series of spring and autumn 2022 are compared against a coupled hydro-thermal numerical simulation solved using a finite element discretization approach in COMSOL Multiphysics. To numerically model the Eden geothermal system, a cubical reservoir including the well trajectory and casing design, and four individual fault zones are considered at a depth between 3830 m and 4280 m TVD. Due to similarity in the geological context on the regional level, permeability, porosity, and other petrophysical parameters of the faulted and matrix properties of the Cornubian granites are considered based on the United Downs geothermal reservoir [2,3]. Initially, the permeability and porosity of the fault zone and matrix are calibrated using the spring hydraulic testing data. Later, the downhole pressure evolution of the spring and autumn injection tests is compared to qualitatively understand any permeability enhancement. Initial results indicate that up to 20% of fault zone permeability enhancement was achieved by the chemical stimulation operation. Future reservoir characterization would be helpful for developing more accurate geochemical models predicting permeability enhancement.

1. Lummer, N.R., Rauf, O. and Gerdes, S., 2015, June. https://doi.org/10.2118/174242-MS.

2. Mahmoodpour, S., Singh, M., Obaje, C., Tangirala, S.K., Reinecker, J., Bär, K. and Sass, I., 2022. https://doi.org/10.3390/geosciences12080296.

3. Reinecker, J., Gutmanis, J., Foxford, A., Cotton, L., Dalby, C. and Law, R., 2021. https://doi.org/10.1016/j.geothermics.2021.102226.

How to cite: Singh, M., Bossennec, C., Bär, K., Reinecker, J., Bilsland, R., Briggs, C., Cotton, L., Gutmanis, J., Bennet, T., Baumgärtner, J., Grand, A., Recalde Lummer, N., Rauf, O., Baujard, C., Genter, A., and Sass, I.: Numerical simulation of fault zone permeability enhancement by chemical stimulation operation at the Eden geothermal projects, UK, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12749, https://doi.org/10.5194/egusphere-egu23-12749, 2023.

10:00–10:10
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EGU23-4979
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On-site presentation
Cornelis Weemstra, Amin Rahimi Dalkhani, Þorbjörg Ágústsdóttir, Egil Árni Guðnason, Gylfi Páll Hersir, and Xin Zhang
We report on a Bayesian (i.e., probabilistic) inversion for the shear-wave velocity structure of the Reykjanes peninsula, SW Iceland. Travel times of Rayleigh waves traversing the peninsula served as input to the probabilistic algorithm. These Rayleigh waves were retrieved through the application of seismic interferometry to yearlong recordings of ambient seismic noise. The Reykjanes peninsula is well placed for this technique because it is surrounded by ocean, which implies a relatively uniform seismic noise illumination; the latter being a condition for accurate interferometric surface wave retrieval. The Bayesian algorithm uses a variable model parametrization by employing Voronoi cells in conjunction with a reversible jump Markov chain Monte Carlo sampler. The algorithm is entirely data-driven, meaning that, contrary to conventional deterministic tomographic inversions, the user does not need to define any regularization or parameterization parameters to solve the inverse problem.
 
The geology in the area of interest is characterized by four NE-SW trending volcanic systems, orientated oblique to the divergent plate boundary cutting across the Reykjanes Peninsula. These are from west to east; Reykjanes, Svartsengi, Fagradalsfjall and Krýsuvík, of which all except Fagradalsfjall host a known high-temperature geothermal field. We observe relatively high shear wave velocity patches close to the Earth’s surface (top two kilometers) at the location of these known high-temperature fields. These high velocity anomalies invert to relatively low shear wave velocities (in comparison to shear wave velocities in the same horizontal plane) at depths greater than 3 km. The latter low-velocity anomalies are relatively small below Reykjanes and Svartsengi. At depths of 5 to 8 km, a low-velocity anomaly extends horizontally below Reykjanes and Svartsengi, correlating relatively well with the inferred brittle-ductile transition below the high-temperature fields at 4-5 km depth. The low-velocity anomaly below Krýsuvík is much larger and coincides with a deep-seated low electrical resistivity anomaly. Horizontally, it coincides with the center of an inflation source at 4–5 km depth. For example, in 2010 this resulted in an uplift exceeding 50 mm/year, but several periods of alternating uplift and subsidence associated with increased seismicity have been observed in Krýsuvík since 2009. Our results both confirm and add details to previous models obtained in the area. Our study demonstrates the potential of Bayesian surface wave inversion as a complementary geophysical tool for geothermal exploration.
 

How to cite: Weemstra, C., Rahimi Dalkhani, A., Ágústsdóttir, Þ., Árni Guðnason, E., Páll Hersir, G., and Zhang, X.: Inferences on the shear wave velocity structure below the Reykjanes peninsula (SW Iceland) from transdimensional ambient-noise surface wave tomography, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4979, https://doi.org/10.5194/egusphere-egu23-4979, 2023.

Coffee break
Chairpersons: Domenico Montanari, Sin-Mei Wu, Paromita Deb
10:45–11:05
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EGU23-12308
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solicited
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Highlight
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On-site presentation
Matteo Lupi

For decades, geothermal energy was harnessed from magmatic systems only. This is no longer the case since projects began to exploit the energetic potential of a variety of geological domains across different tectonic settings. Vertical ground heat exchangers, groundwater aquifers and enhanced geothermal systems are only a few of a large spectrum of solutions proposed to harvest geothermal energy practically anywhere.
Despite lacking high-enthalpy geothermal resources, Switzerland is today one of the leading countries for research and development in the geothermal sector. New projects have been launched, underground laboratories have been developed and a wealth of research opportunities are rising. The new challenges to be faced are supported by solid research schemes fostering interaction between research and industrial partners. I will provide a brief overview of Switzerland’s geothermal roadmap to 2050 describing how the Helvetic confederation is planning to attend about 2 TWh of energy (and about 18 TWh if heat is also considered) by 2050. I will highlight the collaborative research opportunities and the future challenges that our community will have to undertake to foster geothermal energy as a solid and reliable resource to fuel our society across the energetic transition.

How to cite: Lupi, M.: Geothermal Energy in Switzerland: roadmap to 2050, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12308, https://doi.org/10.5194/egusphere-egu23-12308, 2023.

11:05–11:15
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EGU23-12208
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ECS
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On-site presentation
María A. Berriolopez Llamosas, Antonio Olaiz, Alfonso Muñoz Martín, and Gonzalo Zamora

The last few years have been characterized by tremendous global instability due to assure energy supply. Global growth demands more and more resources at the same time as the population´s concern about climate change is increasing. In this context, geothermal energy, a green and renewable energy with the capacity to contribute to the transition of the energy market, is becoming increasingly important. This, together with the improvement in geothermal studies and the development of new exploitation methods, has triggered new geothermal targets to be considered during the last decades.


Geothermal studies in Spain were focused on sedimentary basins and volcanic settings during the 70´s and 80´s. In this framework, few investigations have been done on the western igneous massif of Spain. This study seeks to estimate and resume research on the geothermal potential of the Spanish basement. With that purpose this research analyzes high resolution airborne radiogenic data from Extremadura, Castilla La Mancha and Madrid (Geodata International Inc., 1980), acquired in the 70 and 80´s for uranium exploration, concentration measurements of Uranium, Thorium and Potassium from soil samples (Locutura et al. 2012) and temperature data from widespread hot springs along the studied area.


We have analyzed the concentration of the three heat producing elements in 9 plutons and estimated the heat production of each of them. In this regard, the high airborne-constrained concentrations of the plutons located in the north of Extremadura and west of Salamanca are noteworthy. In this area Uranium reaches 16.43 ppm, Thorium 14.52 ppm and Potassium 6.26 %. Same way a remarkable peak in heat production is located is this area with values up to 5.02 μW/m3. When comparing these data with the values obtained from the soil samples, the correlation between the two is remarkable. Furthermore, the positive radiometric anomalies of both maps coincide with the outcropping of granitic rocks and the location of most of the hot springs.


This work compiles vintage information of diverse origin in order to highlight areas with high geothermal potential in the basement of the westernmost Spain. The results of heat production and their relationship with the hot springs have shown that several of the Paleozoic plutons of the western igneous massif of Spain may have a great potential for geothermal projects.

How to cite: Berriolopez Llamosas, M. A., Olaiz, A., Muñoz Martín, A., and Zamora, G.: Review of existing data for the evaluation and estimation of the geothermal potential in the basement of western Spain., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12208, https://doi.org/10.5194/egusphere-egu23-12208, 2023.

11:15–11:25
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EGU23-9522
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ECS
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On-site presentation
Audrey Taillefer, Laurent Truche, Laurence Audin, Simona Denti, Frederic Donze, Delphine Tisserand, Nathaniel Findling, Laurent Guillou-Frottier, Pablo Jorge Masías Alvarez, Nelida Manrique Lllerena, and Swann Zerathe

In Peru, energy production is more than 75 % dominated by hydrocarbons (IEA, 2018) while at the same time, the Andes forearc is in a full demographic and economic development. However, the geothermal potential associated with reverse fault in the mountain range forearcs remains poorly studied compared to normal faults.  It is then essential to evaluate the geothermal potential associated with the Andes forearc thrust faults, in considering the environmental risks associated.

The hydrothermal system associated with the Sama-Calientes fault, near the city of Tacna South of Peru (18°S) is a suitable field site to experiment how integrated studies could provide an exploration diagnostic. The Calientes hot springs (42-44°C) emerge on the Sama-Calientes fault, an active thrust which delimits the border between the Andes and the north extension of the Atacama Desert. With an integrated study of the hydrothermal fluids and gas geochemistry, XRD composition of the hydrothermal deposits and veins, structural geology, and 3D numerical modeling with COMSOL Multiphysics, we propose to characterize the thermal anomaly associated with the Calientes springs and faults, putting them in perspective with the other hydrothermal springs in the region. Preliminary results indicated that hydraulic breccia, veins, and concretions around the Calientes springs and faults are mainly composed of calcite, contrarily to the other hot springs sites inside the Andes (excepted the Ticaco hot springs). Free and dissolved gas of the springs associated with the high Andean volcanoes (Casiri, Yucamani, Tacora) are mainly composed of CO2 (90-100%), while those associated with the pre-andean faults (Sama-Calientes, Incapuquio) are mainly composed of N2 (60-100%). Volcanic-associated springs show high sulfate concentrations (48-54 mmol/L) compared to fault-associated springs (3-25 mmol/L).  A simple 3D numerical model with a surface DEM and a homogenous permeability indicates that the topography-driven flow lines contributing to the Calientes springs would come from the Tacora volcano, 40 km north-east of Calientes. More investigation will precise the organization of the hydrothermal cells and the associated thermal anomalies. This work will also contribute to understand the role of hydrothermal fluids in subduction zones and especially on seismogenic reverse fault dynamics.

How to cite: Taillefer, A., Truche, L., Audin, L., Denti, S., Donze, F., Tisserand, D., Findling, N., Guillou-Frottier, L., Masías Alvarez, P. J., Manrique Lllerena, N., and Zerathe, S.: Characterization of the geothermal anomaly associated with the pre-andean reverse fault of Calientes, South of Peru: a multi-disciplinary approach., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9522, https://doi.org/10.5194/egusphere-egu23-9522, 2023.

11:25–11:35
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EGU23-12224
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On-site presentation
Bettina P. Goertz-Allmann, Nadège Langet, Alan Baird, Daniela Kühn, and Tina Kaschwich

The Hengill geothermal area is located in southwest Iceland on the plate boundary between the North American and Eurasian plates and is one of the most active seismic zones on the island with thousands of natural earthquakes per year. In addition, seismicity is induced due to active production and injection operations, including the two largest geothermal power plants in Iceland, Nesjavellir and Hellisheiði. In addition, this area is the next target region for the Iceland Deep Drilling Project (IDDP) in search for supercritical geothermal fluids. Detecting and imaging fault zones at high resolution is therefore an important contribution to evaluate the optimum drilling location. We analyze thousands of microseismic events in the area that occurred between December 2018 and August 2021. These events were recorded on different permanent and temporary seismometer networks in the area. In addition, we recorded distributed acoustic sensing (DAS) data along a 25 km long fiber optic telecommunication cable near the Nesjavellir geothermal power plant. We analyze event clustering with a waveform cross-correlation approach and find a clear spatial separation of event clusters delineating planar structures. Clusters experience different temporal evolutions where some develop steadily and others as sudden bursts. Spatial variations of Gutenberg’s b-value and event stress drops show patterns consistent with tomographic seismic velocity inversions. Furthermore, focal mechanisms indicate very consistent source mechanisms within selected event clusters. Along the fiber path, we study waveform characteristics, which correlate with mapped geological features.  Data segments that are recorded where the fiber crosses fault zones exhibit long-tailed codas that may indicate trapping of seismic energy in low-velocity zones around active faults.

How to cite: Goertz-Allmann, B. P., Langet, N., Baird, A., Kühn, D., and Kaschwich, T.: Fault characterization using seismic and DAS recordings at the Hengill geothermal area, Iceland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12224, https://doi.org/10.5194/egusphere-egu23-12224, 2023.

11:35–11:45
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EGU23-12771
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On-site presentation
Claire Bouligand, Yu Liu, Jonathan M.G. Glen, Tait E. Earney, Grant H. Rea-Downing, Laurie A. Zielinski, Branden J. Dean, Leon Kaub, Svetlana Byrdina, Benjamin Lee, Max Moorkamp, Knutur Árnason, Benoît Gibert, and Anette K. Mortensen

During the summers of 2021 and 2022, we conducted drone magnetic surveys over the Krafla geothermal system in the Northern Volcanic Zone of Iceland. The purpose of this survey was to image the subsurface magnetization to help characterize the geometry of the geothermal system and to determine the geological structures and lithologies controlling it. This new survey was collected with two types of magnetometer systems (a fluxgate vector system and a cesium scalar system) fixed to a hexacopter and flown over an area of about 20 km2 with a spatial resolution (i.e. flight line spacing and flight elevation above ground level) of 50 m. The data were corrected for the magnetic effect of the drone using the MagComPy software of Kaub et al. (Geochem. Geophys. Geosyst., 22, e2021GC009745, 2021), for the diurnal variations of the Earth’s magnetic field using a local base-station magnetometer, and for the main (large-scale) magnetic field using the IGRF (International Geomagnetic Reference Model) model. The resulting magnetic anomaly map exhibits a pronounced magnetic low coincident with the active geothermal system. The map also displays many remarkable short-wavelength anomalies associated with topography, cultural features, geological structures such as fault and fissures, areas of superficial hydrothermal alteration and recent lava flows. The comparison of observed and terrain anomalies, the latter computed assuming a constant magnetization of about 10 A/m below topography, suggests a strong influence of topography. However, many discrepancies between observed and terrain anomalies also indicate significant variations of magnetization in the subsurface. We then tested whether we can assume that the main source of rock magnetization variations is a demagnetization associated with hydrothermal processes in the geothermal reservoir. To this end, we used the 3D model of electrical conductivity from Lee et al. (Geophys. J. Int., 220, 541-567, 2020) to evaluate the depth to the top of the geothermal reservoir, characterized by a high conductivity layer interpreted as a clay cap. Magnetic anomalies were then predicted assuming a simple forward model with constant and null magnetization above and below the clay cap, respectively. The resulting predicted anomalies reproduce some large scale features from the observed anomaly map but also display significant differences especially for short-wavelength signals. We therefore inverted for the distribution of magnetization in rocks above the geothermal reservoir using the jif3D code of Moorkamp et al. (Geophys. J. Int., 184, 477-493, 2011) and imposing a null magnetization in the reservoir. The resulting  distribution of magnetization appears to be strongly influenced by the distribution of surface alteration and fresh recent lava flows that were not accounted for in our initial forward model due to both the simplicity of the modeling assumptions and the lower spatial resolution of the electrical conductivity model. This study suggests that the joint inversion of magnetic and electrical conductivity data is a promising approach for the imaging of geothermal systems as it takes advantage of both the sensitivity with depth of electromagnetic methods and the lateral sensitivity of high-resolution magnetic surveys.

How to cite: Bouligand, C., Liu, Y., Glen, J. M. G., Earney, T. E., Rea-Downing, G. H., Zielinski, L. A., Dean, B. J., Kaub, L., Byrdina, S., Lee, B., Moorkamp, M., Árnason, K., Gibert, B., and Mortensen, A. K.: Imaging of the subsurface magnetization of the Krafla geothermal area using a high-resolution drone magnetic survey and constrains from a 3D electrical conductivity model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12771, https://doi.org/10.5194/egusphere-egu23-12771, 2023.

11:45–11:55
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EGU23-7199
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On-site presentation
Chrysanthi Pontikou, Giovanni Toscani, Angelo Ricciato, and Raffaele Di Cuia

Deep geothermal systems as a renewable and green source for energy production and for heating and cooling activities has a great potential for development in many European countries. Also, the need to expand the use of the geothermal resources is well supported by the Foundation for Sustainable Development and meets the goals of the UN 2030 Agenda. Under this perspective, the aim of this research is to study the geothermal energy as an under-exploited tool and how this natural resource could improve and support the ecological transition. The area of interest focuses on the subsurface Cretaceous-Eocene fractured shallow water carbonates (Apulia platform) in the Campania-Lucania sector of the Southern Apennines (Italy), where, based on previous studies, a geothermal positive anomaly has been detected at the level of the reservoir approximately at -3000m (below ground level). The presence of this heat anomaly and in particular the heat transfer mechanism (fluid migration, thermal conductivity, fractures) have not been satisfactorily yet explained from a structural point of view which seems to be one of the key factors for this anomaly. A wide public and confidential database including reflection seismic profiles, well data, gravimetric information and literature from the academia and the Oil and Gas Industry discussing the different structural styles, allowed the re-interpretation and the 3D reconstruction of the geological structures which is subsequently internally characterized by investigating the faults and fractures where hot fluids are present and circulate in the deep subsurface. The structural setting, the physical characteristics of the reservoir rock, the chemical-physical properties of the fluids in the deep subsurface and the dispersion of the heat potential of these fluids as they rise to the surface are all elements that must be considered in the screening phase of potential areas for the development of this geothermal project. We present a comprehensive synthesis of the available data which elaborates the temperature/heat observations derived by the subsurface data and explains sufficiently enough the heat anomaly observed in the area. The geological model is the foundation break of this research and the first fundamental input for the geomechanical characterization of the rock mass by defining the main fracturing trends and the large-scale fractures (discrete fracture network) as the main potential conduits and paths for hot fluid migration and circulation.

How to cite: Pontikou, C., Toscani, G., Ricciato, A., and Di Cuia, R.: 3D Structural modeling for geothermal potential evaluation in Southern Apennines, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7199, https://doi.org/10.5194/egusphere-egu23-7199, 2023.

11:55–12:05
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EGU23-11457
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ECS
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On-site presentation
Alexander Jüstel, Philipp Rubach, Andrea Balza Morales, Michael Kettermann, Oliver Ritzmann, and Florian Wellmann

Geothermal systems have been developed in Paleozoic rocks within the Roer Valley Rift System (RVRS) on the Campine Block in Belgium in the West (e.g. Mol) and the Peel Block in the Netherlands in the East (Tegelen Fault, Californië project). However, no geothermal system has been developed further along the eastern boundary of the RVRS where the tectonically active Viersen Fault Zone (VFZ) is located. This fault zone separates the elevated Krefeld Block from the Venlo Block located near Straelen, Germany. Given the high demand for heat by local greenhouses, the city of Straelen and its surroundings would greatly benefit from geothermal developments. In this study, we aim at characterizing the subsurface structures of the VFZ to estimate the geothermal potential of the Dinantian carbonates, Upper Devonian Condroz sandstones and deeper targets like the Upper/Middle Devonian limestones. This is done by reinterpreting seismic data acquired within the framework of the Californië project, analyzing recently acquired data within the framework of the SCAN project and new gravity measurements performed in the Straelen area. The seismic interpretation indicates fault linkages and relay structures which can be correlated to surface expressions and the recorded gravity measurements. The potential geothermal reservoirs were mapped and horizons were interpolated between the seismic lines with insights provided from gravity results. Our investigations illustrate the previously undescribed segmentation of the Viersen Fault Zone in the Straelen area. This tectonic deformation may promote or enhance fluid flow within the reservoirs in the vicinity of the VFZ similar to the geothermal system developed along the Tegelen Fault in the Netherlands. However, the current permeability of these damage zones in VFZ within the reservoirs requires further local subsurface investigations and in-situ tests through drillings to characterize the hydraulic properties and to map the reservoirs and associated structures in 3D. 

How to cite: Jüstel, A., Rubach, P., Balza Morales, A., Kettermann, M., Ritzmann, O., and Wellmann, F.: Structural setting for a geothermal system at the eastern boundary of the Roer Valley Rift System – A case study from the Viersen Fault Zone in the vicinity of Straelen, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11457, https://doi.org/10.5194/egusphere-egu23-11457, 2023.

12:05–12:15
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EGU23-11067
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ECS
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On-site presentation
Ryan Kurniawan Santoso, Denise Degen, Dominique Knapp, Renate Pechnig, and Florian Wellmann

Drilling of production and injection wells for geothermal exploitation requires accurate knowledge of subsurface structures and processes related to fluid flow and heat transport, reactive transport, and mechanical processes. Since the number of exploration wells is limited, proper characterization of subsurface properties and structures is challenging. Therefore, quantifying uncertainties is essential for estimating the risk in selecting the location of suitable production and injection wells to increase the chance of profitable outcomes.

Uncertainty quantification is often conducted within a probabilistic framework which demands numerous forward model runs. It poses a computational challenge for geothermal applications since many geothermal subsurface models are high-dimensional due to covering a wide range of parameters and utilizing fine meshes to capture complex structures and address coupled processes. In this study, we introduce the use of the non-intrusive reduced-basis method (NI-RB), a physics-based machine learning method, to enable uncertainty quantification also for high-dimensional models. The NI-RB is a model-order reduction (MOR) technique that expresses a physical solution in a linear combination of basis functions and weights. The NI-RB preserves the structure of the physics in the basis functions and uses a machine-learning model to calculate the weight for each basis function. With this method, we can guarantee physical consistency with respect to a full Finite Element simulation in the prediction phase and gain significant speed-ups to enable probabilistic uncertainty quantification analyses.

As a test of feasibility, we use the model of The Hague case (in the Netherlands) to illustrate an uncertainty quantification with a physics-based machine learning method. With the use of this approach, we gain a significant computational speed-up for predicting a new temperature state, from 10 minutes in High-Performance Computing (HPC) infrastructures with 48 cores to 1 millisecond on a conventional laptop with a single core. It, therefore, enables performing a robust uncertainty quantification on such a high-dimensional model in only 30 minutes with 3 million realizations. The trade-off is on time required for preparing training samples for training the machine learning model. The selected training samples must be representative for the desired parameter ranges. We can, then, characterize the temperature distribution at any location with its uncertainty level. This information is valuable for a careful selection of the location of suitable production and injection wells and estimate the possible economic loss.    

How to cite: Santoso, R. K., Degen, D., Knapp, D., Pechnig, R., and Wellmann, F.: Uncertainty quantification with a physics-based machine learning method for geothermal-well targeting: A case study of The Hague, Netherlands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11067, https://doi.org/10.5194/egusphere-egu23-11067, 2023.

12:15–12:25
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EGU23-9422
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On-site presentation
Bernd Leiss, David C. P. Peacock, Ali Abdelkhalek, and Dmitry Romanov

To boost the contribution of geothermal energy to Europe’s energy transition, exploration and exploitation must extend to new regions and play types. The MEET (Multidisciplinary and multi-context demonstration of EGS exploration and Exploitation Techniques and potentials) project included analysis of the potential for an Enhanced Geothermal System (EGS) in the metasedimentary rocks of the Variscan Fold and Thrust Belt in the subsurface at the University of Göttingen, Germany. A feasibility study related to the integration of EGS into the existing district heating system of the Göttingen University campus, which currently uses a natural gas-based combined heat and power plant, presents several scenarios with minimum requirements for cost-effectiveness of the EGS, e.g. a brine flow rate of 30 l/s and brine temperature of 130°C. Mohr diagrams are used to predict the responses of the rocks to thermal and hydraulic stimulation, using information from geological analogue studies in the nearby Harz Mountains, and petrophysical data measured in the laboratory.

We focus on targeting multiple geological horizons to reduce the exploration risk and to optimize the geothermal energy system, including the development of deep, medium deep and shallow geothermal systems for heating, cooling, and heat storage. A concept based on these geothermal systems together with other renewable energies and energy-efficiency measures is proposed. The geology at Göttingen is suitable for such an integrated geothermal system. It includes Variscan basement rocks below ~1500 m, Zechstein layers with salt, gypsum and carbonate layers (up to 500 m thick), and Mesozoic sandstones and possibly karstified carbonates. Unconsolidated Pleistocene sediments are suitable for shallow geothermal systems. The multiple target horizons approach can be more appealing for funding because of the possibilities of higher output and greater efficiency. It will also decrease the exploration risk because fall-back options are available. Involvement and engagement of different stakeholders is a potential barrier to such an integrated approach.

MEET received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement № 792037

How to cite: Leiss, B., Peacock, D. C. P., Abdelkhalek, A., and Romanov, D.: Multiple target horizon exploration for the implementation of an integrated geothermal system for Göttingen, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9422, https://doi.org/10.5194/egusphere-egu23-9422, 2023.

Posters on site: Thu, 27 Apr, 16:15–18:00 | Hall X5

Chairpersons: Paromita Deb, Domenico Montanari, Pilar Sánchez Sánchez-Pastor
X5.367
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EGU23-2534
Jian-Cheng Lee, Gong-Ruei Ho, Chien-Chih Chen, Hsin-Hua Huang, Cheng-Horng Lin, Sherng-Rong Song, Yi-Chia Lu, Hideaki Hase, Chih-Wen Chiang, Yue-Gau Chen, and Sun-Lin Chung

In this study, we conduct a multi-disciplinary study, including geophysics, geochemistry, and geology, in an attempt to reconstruct geothermal geological model(s) at the shallow 3 km, for a project of potential geothermal power generation at the Hongchailin site in the Ilan plain of northeastern Taiwan. Our geophysical techniques include seismic imaging from natural earthquakes as well as ambient noise. Three seismic arrays deployed at different time periods in the past decade were used. We also incorporate geophysical imaging results from previous studies, in particular a series of seismic reflection profiles. For the magnetotelluric (MT) technique, two major surveys have been conducted, including 2015-2018 AMT by National Central University and 2021-2022 MT by GERD and Academia Sinica.  Three test holes were drilled around the Hongchailin site in 2016-2019. Logging and on-site measurements were conducted at increment depths, including stratigraphy and rock types, P/T measurements, fractures analyses, geochemical analyses (e.g., hydrogen/oxygen/helium isotope, fluid inclusion, etc.), and so on.

        Based on regional geology and structures, and incorporating geophysical subsurface imaging, we reconstruct geothermal geological models in line with detailed geological cross sections at the shallow 3 km level. We interpret that there exits a shallow geothermal reservoir within the massive quartz sandstone layers (Szeleng sandstone) at 1-2 km depth with the downhole temperature of 80-100 C.  Geologically, the reservoir is located at the regional Songlo syncline and its south limb; and geophysically, it corresponds to a relatively low resistivity area. Isotope results show that the cool meteoric water came from nearby higher altitude mountain area, then flew through the Szeleng sandstone, which plunges 1-2 km depth below the Ilan plain. Hot fluid is interpreted to be derived from deeper heat source and to be upflowed along a N-S trending vertical faults system near the Hongchailin area.  In addition, two E-W trending major faults, identified by the seismic reflection profiles, seem to be acted as hydrothermal fluid barriers to confine the hot fluid within the reservoir area.

How to cite: Lee, J.-C., Ho, G.-R., Chen, C.-C., Huang, H.-H., Lin, C.-H., Song, S.-R., Lu, Y.-C., Hase, H., Chiang, C.-W., Chen, Y.-G., and Chung, S.-L.: Combining geophysical, geochemical and geological studies toward plausible geothermal models at the Hongchailin site for geothermal power generation in northeastern Taiwan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2534, https://doi.org/10.5194/egusphere-egu23-2534, 2023.

X5.368
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EGU23-6370
Olivier Averbuch, Aurore Laurent, Laurent Beccaletto, Fabien Graveleau, Frédéric Lacquement, Séverine Caritg, Stéphane Marc, and Laure Capar

In the general context of the development of renewable energy in the Hauts-de-France region (N France), some growing interest has been focused recently on the potential of deep geothermy. This area displays favourable conditions due to the burial of a regionally well-defined reservoir, i.e. the Dinantian karstic and brecciated limestones (Lower Carboniferous, 360-330 Ma), below the Nord-Pas-de-Calais coal-bearing Upper Carboniferous basin, developed by flexural subsidence in the foreland of the Northern Variscan frontal thrust system. The predominance of shales within the molassic basin as well as within the basal units at the floor of the thrust wedge (the Lower Devonian clastic units) are furthermore likely to form a large-scale permeability barrier potentially favouring the localization of hot waters within the underlying carbonate reservoir. The occurrence of a Dinantian regional geothermal resource has already been proven in Southern Belgium in the Hainaut coal basin area (the eastern prolongation of the Northern France coal basin) where the temperature in three geothermal wells reaches about 70°C.

To provide further constraints on such potential deep geothermal field in a structurally complex setting (a laterally segmented thrust front), the geometry of the Dinantian reservoir in northern France has been investigated through the integration and interpolation in a 3-D model of a large database including 1 128 boreholes and 532 km of reprocessed, interpreted and depth-converted seismic reflection profiles. The results of the 3-D modelling indicate that the Dinantian reservoir is present at depth over a large area covering approximately 7675 km² in northern France-southern Belgium. It extends at least 30 to 40 km south of the coal mining district area, underneath the Ardennes Allochthonous Unit of the Northern Variscan Front. The Dinantian reservoir is less than 200 m deep in the Lille metropolitan area and strongly deepens southward through a sharp flexure. It reaches 1000-3000 m depth underneath the coal basin and a maximum of 6944 m depth at the southern end of the study area. Overall, the Dinantian reservoir is structured along two main directions oriented N70-80° and N110-130°, related respectively to deep frontal Variscan thrusts and lateral-oblique ramps. The Dinantian reservoir ends west of Douai against a major complex lateral ramp system forming a first-order transfer zone within the Northern France Variscan thrust front. The latter localizes a set of strongly dipping N110-N130 faults (the Artois faults) representing second-order structures produced during subsequent deformation periods i.e. the Late Carboniferous-Permian rifting event and the Tertiary inversion related to the far-field accommodation of the Alpine-Pyrenean shortening.

How to cite: Averbuch, O., Laurent, A., Beccaletto, L., Graveleau, F., Lacquement, F., Caritg, S., Marc, S., and Capar, L.: 3-D geometrical modelling of the Dinantian carbonate reservoir in Northern France: new constraints for the regional development of deep geothermy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6370, https://doi.org/10.5194/egusphere-egu23-6370, 2023.

X5.369
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EGU23-6992
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ECS
Ábel Markó, Marianna Tóth, Maren Brehme, and Judit Mádl-Szőnyi

The so-called Green Transition EU strategy encourages oil businesses to move towards a circular economy and create green energy. The data already collected in the past during hydrocarbon exploration offer enormous possibilities for geothermal reutilization. Revealing this led to the joint project with MOL Plc. to evaluate the geothermal potential for Zala county, Hungary. Although the preliminary geothermal potential of the Zala region (SW Hungary) is assessed to be good, sustainable thermal water use is critical due to the need for reinjection, with only one operating doublet. The study focuses on the geothermal assessment of the siliciclastic Neogene formations.

Due to the need for reinjection wells for sustainable thermal water production, the evaluation has to handle the potential injectivity for the same siliciclastic reservoir. However, several injection-related problems are associated with the Neogene (so-called Pannonian) siliciclastic reservoirs in Hungary. Predicting the issues makes it possible to mitigate them, and it contributes to a “reinjection potential” assessment which can be part of the geothermal potential estimation.

Based on methodological contribution from previous studies (e.g., Markó et al., 2021), this research considers a variety of problem scales, including regional hydraulics, reservoir scale properties, and local clogging processes. As a next step, in the recent study, we investigate the extension of the reservoir sandstone bodies of the deltaic aquifer. This is done by interpreting 3D seismic volumes by amplitude extraction to detect sand-prone volumes combined with well-logs to delineate the reservoir. The analysis helps to predict where to drill the next reinjection well as well as to evaluate the potential of the existing hydrocarbon wells.

The first author was supported, and the research was financed through the KDP-2021 Cooperative Doctoral Programme of the Ministry of Innovation and Technology (Hungary) from the source of the National Research, Development and Innovation Fund, grant number: KDP_2021_ELTE_C1789026. The study was funded by the National Multidisciplinary Laboratory for Climate Change, RRF-2.3.1-21- 2022-00014 project.

How to cite: Markó, Á., Tóth, M., Brehme, M., and Mádl-Szőnyi, J.: Determining the „geothermal reinjection potential” into sedimentary formations using datasets of hydrocarbon exploration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6992, https://doi.org/10.5194/egusphere-egu23-6992, 2023.

X5.370
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EGU23-7884
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ECS
Nicolas Compaire, Michel Campillo, Gregor Hillers, Rita Touma, and Alexandre Aubry

In 2018, the company St1 Oy performed an Enhanced Geothermal System (EGS) experiment using near-real-time seismic monitoring as feedback for the pumping procedure and thus allowing the control of the induced seismicity. Between 4 June and 22 July (49 days), ~18,000 cubic meters of water was injected at around 6 km depth beneath the University campus in Otaniemi, Espoo, Finland (Kwiatek el al. 2019). The hydraulic stimulation and post-stimulation stages were monitored by a temporary ~100 three-components geophone network installed by the Institute of Seismology, University of Finland (Hillers et al. 2020). If the requirements for induced seismicity have been successfully met, the medium changes produced by the hydraulic stimulation remain unclear. Especially with regard to the activation or opening of cracks. Recent application of the distortion matrix concept (Badon et al. 2020) in seismology (Touma et al. 2021) allows us to consider resolving some of these questions by imaging the distribution of the scatterers in the medium during the different injection stages. The distortion matrix operator makes it possible to correct a large part of the aberrations present in images obtained by focusing in depth a reflection matrix recorded at the surface. The phase distortions of the seismic wavefield due to complex velocity distributions can be recovered for any virtual source in the medium by comparing the recorded reflection matrix to the ideal geometric wave-front corresponding to this virtual source. By taking advantage of this powerful approach this study present 3D images of the volume surrounding the injection well of the EGS experiment.

How to cite: Compaire, N., Campillo, M., Hillers, G., Touma, R., and Aubry, A.: Imaging medium changes during a hydraulic stimulation using the distortion matrix framework:  case of an Enhanced Geothermal System (EGS) in Espoo, Finland., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7884, https://doi.org/10.5194/egusphere-egu23-7884, 2023.

X5.371
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EGU23-8220
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ECS
Sin-Mei Wu, Pilar Sánchez-Pastor, Thorbjörg Ágústsdóttir, Anne Obermann, Gylfi Hersir, and Aurélien Mordret

The Hengill volcano system and its adjacent geothermal fields are Iceland's most productive harnessed high-temperature geothermal area. The geothermal resources are powered by cooling magmatic intrusions connected to three volcanic systems, with Hengill being the youngest that erupted ~2000 years ago. This area is located at a triple junction and has, therefore, a highly heterogeneous crustal structure in addition to a fissure swarm intersecting the Hengill volcanic center. Although explorations of Hengill began more than half a century ago, outstanding questions remain, such as the geophysical signature of super-critical fluid and a more detailed understanding of the underlying geothermal resources. Our particular focus in this work is to explore how high-resolution 3D isotropic and anisotropic seismic velocity models can help to address relevant questions in Hengill.

We perform ambient noise Rayleigh and Love wave imaging by combining a 498-node dense geophone array and a 44-station seismic backbone network. The backbone netowrk has ~2.5 years of data between late 2018 and 2021, with a >3 km station spacing and up to 40 km aperture. The dense array data, targeting provisioned geothermal subfields in the northern and southern parts of Hengill, was acquired through a 1–2 months campaign in the summer of 2021, with a <500 m station spacing and an aperture of 20 km. We demonstrate that, even with the shorter duration of data, the seismic imaging capacities are greatly enhanced in the top 5 km compared to the images retrieved from the backbone network alone. In addition to the shallow structure (<2 km), the dense sampling with good azimuthal coverage provides essential constraints on the deeper structure (>2 km). We observe a primary slow velocity anomaly at ~4 km depth which we associate with solidified magmatic intrusions. The trend of the anomaly is perpendicular to the NE striking Hengill fissure swarm, coinciding with a previously found deep lying low-resistivity anomaly. We find that most of the earthquake locations are near the margin of velocity contrasts, indicating a structure or permeability change in the subsurface.

From the anisotropy model, we observe a predominant fast direction along the vertical axis in the top 2 km of crust, implying an overall vertical crack formation resulting from extensional stress with ~10 mm/yr westward deformation. From 3 to 5 km depth, the fast direction transitions to the horizontal axis, broadly in agreement with intrusions or lava deposits. Around the same depth, the southwestern Hengill geothermal field remains in the vertically-fast direction. This area resides in the junction of distinct geologic, tectonic, and geodetic manifestations. We hypothesize that the extension of  vertically-oriented formation toward depth relates to crustal thinning and increasing permeability that promote one of the powerful boreholes in Hengill.

 

How to cite: Wu, S.-M., Sánchez-Pastor, P., Ágústsdóttir, T., Obermann, A., Hersir, G., and Mordret, A.: Multiparapmeter Seismic Tomography Across High-Temperature Geothermal Field in Hengill (Iceland) Using a Large-N Nodal Array, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8220, https://doi.org/10.5194/egusphere-egu23-8220, 2023.

X5.372
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EGU23-9144
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ECS
Meysam Rezaeifar, Christopher J. Bean, Duygu Kiyan, Brian O’Reilly, Colin Hogg, Patrick Meere, Javier Fullea, Sergei Lebedev, Tao Ye, Emma L. Chambers, Aisling Scully, and Gaurav Tomar and the DIG team

One key aim of the DIG (De-risking Ireland’s Geothermal Energy Potential) project is to determine and evaluate the potential low-enthalpy geothermal resources at reservoir scale in the Mallow warm springs area (MWSA), by performing a joint interpretation of new and existing geophysical, geochemical and petrophysical datasets together with structural geology and hydrochemistry results.

As a first step, based on the ambient detected noise sources in the study area, about 100 seismic stations (5Hz nodes) were deployed for two weeks along the railway, straddling fault structures that are thought to control hot spring fluid flow in the Mallow area. We performed seismic interferometry imaging on the recorded train-induced vibrations to map shallow subsurface (top ~2 km) structures and to extract the physical properties (e.g. seismic velocity and density) of these structures. Preliminary result shows a good correlation between S-wave velocity variation and the near-surface lateral changes of lithology, especially across the Killarney-Mallow Fault Zone (KMFZ).

In the next step, 2D interactive modeling of the gravity data was performed, using physical properties determined from the previous step to constrain shallow structures. Additionally, we used the result from the receiver function method that is applied to the data recorded by four broadband stations in the study area, in order to better constrain the deeper interfaces. The 2D inversion of gravity data reveals an anomalous zone in the vicinity of the KMFZ that could be related to the possible fault conduit, associated with the Mallow warm springs area.

The project is funded by the Sustainable Energy Authority of Ireland under the SEAI Research, Development & Demonstration Funding Programme 2019 (grant number 19/RDD/522) and by the Geological Survey Ireland.

How to cite: Rezaeifar, M., Bean, C. J., Kiyan, D., O’Reilly, B., Hogg, C., Meere, P., Fullea, J., Lebedev, S., Ye, T., Chambers, E. L., Scully, A., and Tomar, G. and the DIG team: The shallow subsurface characterization in relation to geothermal resources in the Mallow area, Ireland, using passive seismic and gravity data inversion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9144, https://doi.org/10.5194/egusphere-egu23-9144, 2023.

X5.373
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EGU23-11877
Emmanuel Gaucher and Robert Egert

Sustainable and efficient use of the geothermal resource sitting below the city of Munich (Germany) is a topical issue for the local energy providers. Indeed, by 2035, Munich city expects to supply 100 % of its electricity and heat demand from renewable energies. Hence, the exploitation of the highly conductive aquifers will be intensified with the development of numerous new geothermal power plants. This is a challenging task, which requires better understanding of the coupled processes taking place underground and of their effects, especially in terms of possible induced seismicity and ground uplift or subsidence. These last two concerns are at the heart of the INSIDE research project. The present study focuses on the thermo-hydro-mechanical (THM) modelling of the deep geothermal site in Pullach im Isartal (close to Munich), which constitutes one step to reach the overall project goal.

At the Pullach site, since 2005, a deep geothermal reservoir in the Mesozoic Malm is successfully operated and supplies heat to the local grid. A finite-element (FE) reservoir model is developed consisting of eight different lithologies ranging from the crystalline basement to the Earth’s surface. Focusing on the Malm geothermal reservoir, the lithology of interest is subdivided into the three potential and permeable reservoir rocks of the lower, middle and upper Malm. The three geothermal wells are included with their real trajectories and open-hole sections as lower-dimensional elements. The FE model is used to simulate the fully-coupled THM processes taking place under continuous operation using the TIGER open-source application, which is based on the Multiphysics Object-Oriented Simulation Environment (MOOSE).

The 3D numerical model was calibrated using hydraulic tests conducted at the wells and the continuous operation of the plant, running for many years, gave the opportunity to assess the simulation results. Consequently, predictions of the long-term changes of the THM characteristics of the geothermal reservoir for the next 50 years are expected realistic. The results show that, under our assumptions and the current operational conditions, exploitation will remain sustainable in the future. Furthermore, near the injection well, a long-term increase in porosity and permeability should be expected due to thermo-poroelastic effects. At last, millimetre-scale uplift could be observed at surface above the injection well.

In addition to the present exploitation schemes, several scenarios to increase the exploitation using additional wells are investigated. A similar approach is taken, but particular attention is paid to possible interferences between existing and future neighbouring wells due to enhanced reservoir utilization.

How to cite: Gaucher, E. and Egert, R.: Change of the THM properties of a Malm geothermal reservoir under present and future exploitation schemes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11877, https://doi.org/10.5194/egusphere-egu23-11877, 2023.

X5.374
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EGU23-12919
Hartwig von Hartmann and Nana Yaw Ofori-Amanfo

What are the main challenges of exploring geothermal reservoirs with low temperatures, so-called low-enthalpy systems? A typical situation in European countries, especially Germany, is regionally different in high information density due to former intensive exploration activities for hydrocarbons. Regionally there are concepts of more or less successful exploitation for geothermal projects based on special subsurface conditions, which allow high water production at high temperatures. The development of such regions where geothermal energy plays an essential role in the energy supply extends over decades. Uncertainties in reservoir characterization lead to high investment risk and a lack of economic viability. The increase in energy costs and the intensified search for climate-neutral energy has recently intensified the search for suitable reservoirs for geothermal use. In this context, the development times of geothermal projects must be shortened, and possible reservoirs must be systematically surveyed. Exploration plays one or even an essential role. Even if the state assumes costs and risks, concepts for exploration must be developed according to the current state of the art.

A closer look reveals that even in areas with a high information density, more than knowledge about the subsurface beyond the hydrocarbon reservoirs is needed for geothermal use. The exploration goal in geothermal energy so far has been mainly structural exploration. To better estimate the reservoir quality, understanding the depositional space and subdivision into different facies is necessary. These tasks are then the basis for estimating petrophysical parameters for reservoir characterization. Here, newer interpretation techniques help to perform such tasks quickly.

An example of an interpretation of a 3D seismic dataset from the Bavarian Molasse illustrates this. The Tertiary sediments of the Molasse basin are composed of marine sequences, redeposition of debris fans of the adjacent Alpine region and drainage systems of the basin. Due to regionally different uplift and subsidence of the basin, east-west directed trends exist in the respective depositional systems. In the region studied here, these changes are extreme. The goal was to find and map evidence of fluvial systems in the depositional settings. The seismic patterns are very heterogeneous, and there are only a few continuous reflectors to subdivide the study area. Indications of fluviatile deposits are not evident at first.

By calculating local inclinations and inversion techniques, a variety of so-called phantom horizons can be generated and then visualized with different seismic attributes. This way, fluviatile patterns could be recognized in a 300m thick part of the Aquitaine. The mapping of these patterns followed a further step by exploiting the corresponding signals' similarity and spatial connections. Machine learning can perform further facies discrimination but cannot recognize these fluviatile patterns.

The work showed that existing data, with appropriate processing and new interpretation methods, can be efficiently used to search new geothermal reservoirs systematically. The scientific challenge that industrial orders cannot solve is a more detailed analysis of the evolution of the sedimentation space. However, this is necessary for the transfer of results to neighbouring areas.      

How to cite: von Hartmann, H. and Ofori-Amanfo, N. Y.: Challenges for geothermal exploration- fluviatile systems and new interpretation techniques, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12919, https://doi.org/10.5194/egusphere-egu23-12919, 2023.

X5.375
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EGU23-12965
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ECS
Karen Nicollet, Francisco Muñoz, Geneviève Savard, Domenico Montanari, Michele d'Ambrosio, Gilberto Saccorotti, Davide Piccinini, Nicola Piana Agostinetti, Juan Luis Porras Loria, Konstantinos Michailos, Riccardo Minetto, Marco Bonini, Chiara Del Ventisette, and Matteo Lupi

The Northern Apennines hinterland is normally referred to as a back-arc area affected by magmatism since the late Neogene, with intrusive and extrusive magmatic rocks being scattered through the southern Tuscany and the Tuscan Archipelago. This setting makes this geothermal area one of the most important worldwide.  The very high geothermal gradient of the Tuscan Magmatic Province (up to 200–1000 mW/m2 in the central part of the Larderello-Travale geothermal field) fuels vigorous fluid flow that promotes a widespread geothermal activity. The plumbing magmatic systems progressively migrated eastwards. In Tuscany, the Elba Island is proposed to be the ancient (and now exhumed) analogue of the Larderello-Travale geothermal system where Pliocene to Pleistocene granites have been found at about 3 km depth. The occurrence of such magmatic bodies links to one of the most debated structures of the region, namely the K-horizon seismic reflector. Early authors suggest that this level may represent the transition between ductile and brittle geological units. Other authors propose that the k-horizon may represent a level where the magmatic brines released by the cooling plutons are stored at super-critical conditions.

To understand the spatial and temporal relationship between tectonics and eastwards migration of magmatism, we deployed a seismic network composed of 30 broadband sensors that complemented the permanent INGV network from September 2020 to August 2021. We used QuakeMigrate to build the seismic catalogue and identified 915 events. The seismic activity is well spread across the region and occurs in swarm sequences in areas marked by higher geothermal gradients, particulary in the Larderello-Travale geothermal field. We investigate the seismic clusters and compare them against the locations obtained with the permanent monitoring network. Our results significantly reduce the magnitude of completeness for the Northern Appennines hinterland and provide new insights into the tectonics of the region. This study will be continued with a newly funded project that will use ambient noise methods acquired by nodal networks to provide high-resolution tomographic inversions of the geothermal systems of the Tuscan Magmatic Province.

How to cite: Nicollet, K., Muñoz, F., Savard, G., Montanari, D., d'Ambrosio, M., Saccorotti, G., Piccinini, D., Piana Agostinetti, N., Porras Loria, J. L., Michailos, K., Minetto, R., Bonini, M., Del Ventisette, C., and Lupi, M.: Seismic methods to investigate the interplay between magmatism and tectonics in the Northern Apennines hinterland, Tuscan Magmatic province, Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12965, https://doi.org/10.5194/egusphere-egu23-12965, 2023.

X5.376
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EGU23-13667
Domenico Montanari, Giovanni Ruggieri, Marco Bonini, and Maria Laura Balestrieri

High enthalpy geothermal fields are typically associated with magmatic intrusions providing the heat source that makes the system working. To identify and locate these features, geothermal exploration generally uses expensive, time-consuming approaches that could also require complex logistics. Here we present the result of a pilot study carried out in the well-known Larderello-Travale geothermal field (Tuscany, Italy), exploring the possibility of an advantageous use of low temperature thermochronology to obtain useful information implementing the geothermal exploration workflow. The majority of the collected samples (except one retaining the apatite fission-track age of undisturbed, or almost undisturbed country rocks) cluster in a close time span ranging between 3.1±0.8 and 1.9±1.1 Ma, which clearly matches the known ages of magmatic bodies in the region. We propose that this approach can contribute to the identification of sectors recently affected by thermal perturbations that could have led to the development of hydrothermal systems. This approach has allowed us to achieve clues for the presence of subsurface magmatic intrusions even in areas where currently there are no direct indications. Given the small number and distribution of analyzed samples, our contribution represents a first attempt that demonstrates the potentiality of the method in geothermal exploration, but that needs to be verified by further studies involving a larger sampling density. Overall, our results suggest how low temperature thermochronology can be a powerful, fast, and cost-effective tool for geothermal exploration, to be used jointly with the classical methods.

How to cite: Montanari, D., Ruggieri, G., Bonini, M., and Balestrieri, M. L.: Low temperature thermochronology as a tool for geothermal exploration: A promising test from the Larderello-Travale Geothermal Field (Italy)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13667, https://doi.org/10.5194/egusphere-egu23-13667, 2023.

X5.377
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EGU23-14708
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ECS
Pilar Sánchez-Pastor, Sin-Mei Wu, Ketil Hokstad, Bjarni Kristjánsson, Vincent Drouin, Gunnar Gunnarsson, Cecile Ducrocq, Antonio Rinaldi, Anne Obermann, and Stefan Wiemer

Seismic noise interferometry (SNI) is based on the computation of seismic response by extracting correlated wavefields from continuous seismic recordings. This seismic response is understood as the Green’s function of the propagation medium and it is typically used to image the subsurface. Furthermore, a regular retrieval of this magnitude in time enables the identification of changes in the structural and mechanical properties of the subsurface and therefore, it can be also used for monitoring purposes.

Here, we use SNI to monitor the steam content in geothermal reservoirs. The massive extraction of fluids commonly causes a pressure drop in the rock matrix and land subsidence in the surroundings of production areas. Furthermore, the boiling point decreases yielding decompression boiling. Estimating the steam fraction at depth is challenging especially in reservoirs with two-phase fluids. In this work, we focus on the Hengill geothermal area (Iceland), where the steam ratio has increased by around 30% in the last 10 years due to the harnessing of geothermal energy.

In this area, we measure the land deformation with synthetic aperture radar interferometry (InSAR) and estimate seismic velocity changes with SNI. We observe that both magnitudes linearly decrease in the long term accordingly to the energy production. Besides, we model the expected seismic velocity drop with in-situ borehole data (temperature, pressure, and steam ratio) and conclude that the seismic velocity drop might be related to the steam evolution within the reservoir. These results offer an innovative way of estimating the steam content in the crust with a surface and non-invasive technique.

How to cite: Sánchez-Pastor, P., Wu, S.-M., Hokstad, K., Kristjánsson, B., Drouin, V., Gunnarsson, G., Ducrocq, C., Rinaldi, A., Obermann, A., and Wiemer, S.: Monitoring steam content in the crust with seismic noise, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14708, https://doi.org/10.5194/egusphere-egu23-14708, 2023.

X5.378
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EGU23-15263
Maria Ask and Simona Pierdominici

About half of all heating in Sweden comes from district heating, which makes it the most common form of heating in Sweden. The Otaniemi deep drilling project by St1 in Finland was a game changer, as it launched the idea to feed district heating systems with fossil-free, sustainable geothermal heat from great depths. Göteborg Energi AB has been conducting an exploration drilling program over the last three years targeting major Precambrian deformation zones in radiogenic heat-producing granites. The in-situ temperatures of these granites are boosted by radioactive gamma-ray decay from heat producing elements (K, U, Th). The objective is to develop an engineered geothermal system at 5-7 km depth where the groundwater temperatures reach 120°C to feed the local district heating system. Knowledge of the state of stress is central for this development because it provides insights for the understanding bedrock stability, induced seismicity and fluid flow patterns.

A first 1 km deep sub-vertical borehole in Högsbo was fully cored in 2021, and a second 1 km long inclined borehole in Sisjön was completed in 2022, less than 5 km south of the first borehole. Downhole logging was conducted in both boreholes to constrain downhole temperature, natural gamma radiation, fracture occurrence and orientation of in situ stress.

An acoustic borehole televiewer was used to map fracture occurrence and their geometry, as well as to investigate if stress-induced failure has occurred in the wellbore. For vertical boreholes, drilled parallel with a principal (vertical) stress, borehole breakouts and drilling-induced tensile fractures reveal the orientation of minimum- and maximum horizontal stress, respectively, if the tangential stress concentration generated by the borehole overcomes the compressional and tensile strength of the rock mass, respectively. Here, the objective is to investigate stress-induced failure in an inclined borehole, that is not aligned with a principal stress.

We analysed and processed acoustic borehole images from the Sisjön borehole and mapped fractures occurrence and stress induced features (borehole breakouts and drilling-induced tensile fractures). We have detected some stress-induced features at about 400-500 m depth, but most stress-induced features occur below 800 m. Preliminary results of drilling-induced tensile fractures suggest an orientation of maximum horizontal stress of 145±10°N along the inclined borehole. Corresponding mean orientation from borehole breakouts is slightly lower (132±21°N). More detailed studies are required to confirm the preliminary observations, and to account for the borehole inclination.

How to cite: Ask, M. and Pierdominici, S.: Constraining horizontal stress orientations for geothermal exploration in the inclined Sisjön borehole, Southwest Sweden, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15263, https://doi.org/10.5194/egusphere-egu23-15263, 2023.

X5.379
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EGU23-14105
Michael Kettermann, Oliver Ritzmann, Jens Battermann, and Florian Wellmann

Deep geothermal aquifers can be a good source for industry applications with a high heat demand in the course of the energy transition. Industries such as paper production require heat sources that are independent of global market fluctuations, with predictable, reliable and green long-term supply. A number of clastic aquifers have been identified as potentially feasible for geothermal use within the North German Basin ranging from the lower Cretaceous to Middle Bunter Sandstone. Due to the extensive hydrocarbon exploration in the North German Basin, it is often possible to provide a local subsurface analysis of the geothermal potential at the location of the required use.

In this work, we present a case study from the town of Hoya in the southern North German Basin, where an abandoned hydrocarbon exploration well is available, as well as numerous wells in the vicinity (20 km) and some 2D seismic lines. From well log analysis, well reports, seismic data and an available 3D model of Lower Saxony, we evaluate the quality of different clastic reservoirs in the study area. We found? that many of the reservoirs that are known for good quality sandstones in the North German Basin are presented as shales at the paper mill in Hoya. Potentially usable sandstone reservoirs include the lower Cretaceous Aptian (top ca. 1600 m) and Valendis Sandstone (top ca. 1700 m), the middle Jurassic Dogger Delta 2 (top ca. 1950 m) and the Lower Triassic Hardegsen Sandstone (top ca. 3850 m). Surrounding well data, however, show a large spatial heterogeneity for these lithologies over relatively short distances. We include these geological uncertainties, temperature measurements from wells, permeability measurements from well tests and the specific requirements of a paper production company to evaluate the geological and economic feasibility, based on geothermal energy estimations and levelized costs of heat for the individual reservoirs.

How to cite: Kettermann, M., Ritzmann, O., Battermann, J., and Wellmann, F.: Potential for deep geothermal heat production in clastic rocks of the southern North German Basin – A case study from Hoya, Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14105, https://doi.org/10.5194/egusphere-egu23-14105, 2023.

X5.380
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EGU23-14534
Deyan Draganov, David Naranjo, Katerina Polychronopoulou, and Cornelis Weemstra

Geothermal energy is a cleaner and more sustainable source of power, which plays a key role in the transition to a low-carbon economy. Sustainable and safe exploitation of geothermal resources, however, depends on our ability to understand and manage the associated seismic risks. In 2018, Nature's Heat geothermal project began operations in Kwintsheul, Netherlands, aiming to supply heat to 64 hectares of greenhouses. Between July and October 2019, a temporary seismic array was installed to monitor for possible seismic activity at the site. Microseismic moment-tensor inversion is a valuable tool for understanding the mechanics and structure of geothermal reservoirs, and for optimizing their exploitation. It can be challenging, though, to apply this technique when there are high levels of ambient seismic noise, as is often the case in geothermal operations in densely populated areas. In this study, we evaluate the feasibility of inverting the centroid moment tensor of microseismic events in Kwintsheul, using probabilistic moment-tensor inversions. We first test the probabilistic inversion using synthetic recordings of ambient seismic noise, after which we apply the technique to the low-magnitude (Md=0.16) event recorded on July 14, 2019. Our results give insight into the challenges and limitations of applying moment-tensor inversion to low-magnitude events in the context of geothermal operations in the Netherlands.

How to cite: Draganov, D., Naranjo, D., Polychronopoulou, K., and Weemstra, C.: The potential of probabilistic moment-tensor inversions for the characterization of geothermal reservoirs in urban environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14534, https://doi.org/10.5194/egusphere-egu23-14534, 2023.

X5.381
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EGU23-12480
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ECS
Kaiu Piipponen, Alvar Soesoo, Heikki Bauert, and Teppo Arola

Production of geothermal energy relies heavily on subsurface properties. In low-enthalpy geothermal regimes, thermal energy extracted with a borehole heat exchanger (BHE) is the subsurface heat conducted from the rock and grout to the BHE fluid. No subsurface fluids are pumped in or out of the BHE system in the process. However, groundwater flow can bring warm or cold fluid from the surroundings which changes the temperature profile in the well and the vicinity and thus it can affect well heat production.

The geology in Estonia provides a good opportunity to study the groundwater influence on the BHE systems. In Estonia, several hundred meters thick Lower Palaeozoic sedimentary rock sequence is mostly covered by relatively thin Quaternary sediments, while the underlying Lower Proterozoic crystalline basement rocks occur at depths from 150 m in North Estonia to over 600 m in South Estonia. The main groundwater aquifers are confined to the Palaeozoic sedimentary rocks. In North Estonia, the main groundwater aquifers overlying the crystalline basement rocks are Gdov, Voronka, Cambrian-Vendian, Ordovician-Cambrian, and Silurian-Ordovician aquifers. Those aquifers have different thermogeological and hydrogeological parameters shown by several groundwater hydrogeological and hydrodynamic studies and modelling. Only a few geothermal energy studies have been conducted in the Estonian geological setting and the groundwater effects on the geothermal energy budget on the shallow to medium depth geothermal energy systems have not yet been studied in detail.

In this study, we parametrized different hydraulic conditions to compare how the groundwater flow velocity impacts the thermal energy yield of the geothermal system. We modelled single BHEs of lengths of 400 m, 500 m and 1000 m and a BHE field of ten 400 m wells at three sites across Estonia. 400 m wells have a U-tube type heat collector grouted with bentonite clay and the 500 m and 1000 m wells have a coaxial heat exchanger of plastic pipe or a vacuum-insulated tube (VIT), respectively. Our results demonstrate that 1) the thermogeological parameters of the area, such as subsurface temperature and thermal conductivity, are the most significant factor in the thermal energy yield of the wells and 2) at all sites, shallow BHEs are sensitive to the added groundwater flow, whereas 1-kilometer-deep coaxial wells with VIT are the least sensitive to the addition. An interesting highlight is that the increase in the thermal energy yield is not consistent at different locations with the groundwater flow variation. At sites where the aquifers are located deep with respect to the borehole length, an increase in groundwater flow velocity brought more advantages than at sites where permeable layers are distributed more evenly or near the top of the geothermal well.

How to cite: Piipponen, K., Soesoo, A., Bauert, H., and Arola, T.: Modelling Impacts of Groundwater Flow on Borehole Heat Exchangers: Lessons Learned from Estonia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12480, https://doi.org/10.5194/egusphere-egu23-12480, 2023.

X5.382
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EGU23-14928
Andreas Reinicke, Paromita Deb, Martin O. Saar, Vedran Zikovic, V., Erich Lassnig, Marcel Knebel, and Jan Jette Blangé

Reliable delivery of economic well performance of geothermal projects is affected to a high degree by uncertain reservoir quality. Construction of multilateral wells is well known as an effective concept to overcome the challenges of reservoir heterogeneity or low permeability by increasing the reservoir contact. However, the drilling costs for these structures are currently very high and multilateral well construction with standard rotary steerable systems is complex. Canopus’ directional steel shot drilling system (DSSD) has the potential to enable the construction of short-radius multilaterals at rates attractive for geothermal applications.

As part of the European GEOTHERMICA project ‘DEPLOI the HEAT’, the operational performance and economic impact of Canopus’ DSSD system will be investigated. Full-scale tests at TNO’s Rijswijk Centre for Sustainable Geo-Energy (RCSG) and a field trial at the Hagerbach underground test facility (VSH) are planned for the first project year. The RCSG drilling rig enables full factory acceptance testing (FAT) of the drilling assembly before the trial at the VSH site is executed. The geology at the VSH site reflects conditions of typical mid-depth fractured limestone reservoirs in Switzerland and elsewhere. At VSH, a complete set of operational parameters and system longevity will be tested with a full-scale trial to prepare for live well deployment.

Further, a techno-economic assessment of multilateral structures drilled with Canopus’ DSSD system will highlight the potential for increasing or safe-guarding well productivity and economically de-risking geothermal projects. Several operators are involved in this project and the techno-economic assessment of the drilling technology will be based on several site-specific data sets provided by them. Stochastic modeling approaches will be implemented to generate an ensemble of equally probable realizations of permeable structures in the subsurface. Then, the performance and costs of different well geometries and multilateral configurations in different subsurface model realizations will be evaluated and compared.

The current status of this project will be presented with a focus on the factory acceptance testing at TNO, the VSH trial preparations and the workflow developed for the techno-economic assessment of this innovative multilateral drilling technology.

How to cite: Reinicke, A., Deb, P., Saar, M. O., Zikovic, V., V., Lassnig, E., Knebel, M., and Blangé, J. J.: Novel Directional Steel Shot Drilling Technology for Short-Radius Multilaterals – Field Application and Commercial Impact, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14928, https://doi.org/10.5194/egusphere-egu23-14928, 2023.

X5.383
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EGU23-14202
Mirja Pavić, Maja Briški, Marco Pola, and Staša Borović

A hydrochemical and geothermometric study of thermal waters in Topusko (Croatia) was conducted in order to improve the existing conceptual model of the Topusko hydrothermal system. The town of Topusko is located 80 km south of Zagreb at the SW edge of the Pannonian Basin System, which has favourable geothermal characteristics. The natural thermal springs of Topusko with temperatures up to 53°C and thermal waters from shallow wells with temperatures up to 65°C represent the second warmest natural thermal water source in Croatia. Water samples have been collected monthly since March 2021 from two natural thermal springs, i.e. Livadski izvor and Blatne kupelji springs, and the TEB-4 thermal well in the discharge area of the hydrothermal system. Furthermore, rainwater was sampled in the supposed recharge area. Chemical composition of groundwater is determined by the original composition of the infiltrated water as well as chemical reactions with various rocks along its circulation path. In-situ parameters, major anions and cations, stable water isotopes, radioactive isotope analysis of tritium (3H), and silica geothermometers were used to assess the origin of thermal waters in Topusko and their interaction with the thermal aquifer. Furthermore, a local meteoric water line was constructed and compared with the isotope ratio of the thermal waters. The results pointed to: i) the meteoric origin of thermal waters according to stable water isotopes; ii) Ca-HCO3 hydrochemical facies suggesting that carbonate dissolution occurs in the aquifer, being consistent with the presence of carbonates in the stratigraphic logs of wells; iii) an equilibrium temperature in the reservoir of 88°C according to silica geothermometers; and iv) low tritium activity being consistent with sub-modern waters and a recharge before 1955. The monitoring of these thermal springs will continue for another year to collect a larger dataset and reinforce our conclusions. Additional analyses including radiocarbon dating and stable isotope composition from SO42- will be conducted to provide a comprehensive hydrochemical characterisation of these thermal waters, which have been utilised since ancient Roman times, and intensively since 1980s, but have not been thoroughly investigated.

Acknowledgments: Presented research has been conducted in the scope of the project “Multidisciplinary approach to hydrothermal system modelling” (HyTheC) funded by the Croatian Science Foundation under grant number UIP-2019-04-1218.

How to cite: Pavić, M., Briški, M., Pola, M., and Borović, S.: Hydrogeochemical research of thermal waters from Topusko, Croatia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14202, https://doi.org/10.5194/egusphere-egu23-14202, 2023.

X5.384
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EGU23-8110
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ECS
Felix Schölderle and Kai Zosseder

Forecasting of downhole temperatures is of great interest for the development of deep geothermal energy, since the maximum production temperatures are important for the efficiency of the system. The production temperatures are mainly determined by the prevailing reservoir temperature, which is insufficiently known even in well-developed reservoirs. 

Most available temperature data from hydrothermal reservoirs are “bottom hole temperatures” (BHTs) that are usually measured during geophysical measurement programs, after each section of a deep geothermal well has been drilled. These measured temperatures are thermally disturbed by the preceding drilling fluid circulation and therefore show a high deviation from the undisturbed formation temperature, requiring correction of the BHT measurements. This is made possible by a variety of analytical and numerical BHT correction methods, all of which require different input parameters for each method. Those parameters are often documented with poor quality, incompletely, or not at all. It can be assumed that the inaccuracy of a corrected BHT value depends to a high degree on the errors of the input parameters and the choice of the correction method is secondary in this respect.

In order to perform a complete evaluation of corrected BHT values and to determine the range of errors, we corrected BHT values from over 300 current geothermal and old hydrocarbon wells in the Bavarian Molasse Basin in Southern Germany using a Monte Carlo approach. Thus, the corrected temperature was given as a density distribution rather than a discrete value after individual estimation of the error in the input parameters. This allows a prediction of the formation temperature based on risk scenarios, for example specifying a p10 or p90 case.

From the corrected temperatures and taking into account the individual variances studied (p10 and p90 values); we created a set of temperature gradients that take into consideration, if known, the discovered inflow zones and the slope changes in the stratigraphic layers. This approach provides a spatial representation of temperatures while accounting for error propagation by estimates in the correction process, as well as the extrapolation of point temperature data to gradients and the application of geo-statistical methods.

How to cite: Schölderle, F. and Zosseder, K.: Mapping regional variability of reservoir temperatures for hydrothermal use: a statistical model based on parameter uncertainty, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8110, https://doi.org/10.5194/egusphere-egu23-8110, 2023.

Posters virtual: Thu, 27 Apr, 16:15–18:00 | vHall ERE

Chairpersons: Kai Li, Sin-Mei Wu, Pilar Sánchez Sánchez-Pastor
vERE.1
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EGU23-872
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ECS
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Susmita Goswami and Abhishek Rai

Geothermal energy is an important source that has the potential to contribute to the energy needs of society. In this study, we try to understand the hydro-geological characteristics of the hot springs located in the two important coastal terrains of India. i.e., East Coast and West Coast. Our findings indicate that the west coast springs are dominated by Na-Cl, Ca-SO4, and Na-HCO3 water types, indicating that seawater intrusion through deep penetrating faults and fractures may have an impact. The majority of the east coast's hot springs which are located in Odisha have Na-Cl, and Ca-HCO3 water types and a short residence period. According to our findings, hot springs on the west coast have a higher potential compared to Odisha for producing geothermal energy. We find that hot springs on the West Coast are mostly composed of Na-Cl, Ca-SO4, and Na-HCO3 water and that they may be influenced by seawater intrusion. Hot springs on the east coast, particularly in Odisha, have Na-Cl and Ca-HCO3 water and have a short residence period. Some ionic concentrations have a strong correlation, indicating that seawater-rock interactions were dominant in the West Coast and some springs of Odisha thermal springs. The reservoir temperatures for the west and east coast springs, using the saturation-index method is found to be 120±5°C and 110±5°C. The reservoir depths and geothermal fluid circulation depths are estimated to be 1.71 ±0.17km and 1.37±0.32km, respectively. The control of water circulation in hot-spring systems is largely dependent on faults and subsurface high heat flow.  In comparison to Odisha, the West Coast thermal water is heated at a greater depth (1.71±0.17km at 120±5°C); circulation and mixing of thermal water via deeply connected faults and NNW-SSE lineaments. The West Coast springs' reservoir and geothermal fluid circulation depths are greater than those of Odisha, indicating greater circulation.

How to cite: Goswami, S. and Rai, A.: A Comparative Study of Geothermal Potential of the East and West-Coast Hot Springs, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-872, https://doi.org/10.5194/egusphere-egu23-872, 2023.

vERE.2
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EGU23-8945
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Ernesto Macedo Serrano and Rosa María Prol Ledesma

The regional evaluation of the intraplate volcanism province is attempted using the Play Fairway Analysis. This province is characterized by recent alkaline volcanism that is not related with the previous Farallon Plate subduction of the present Cocos Plate subduction. This volcanism is constrained to the main structures related with the Basin and Range processes of extensional tectonism.

A geographic information system is constructed by including geological and geophysical data. Thematic maps are developed with the information that is considered relevant for the location of areas with favorable conditions to host geothermal systems, with or without surface manifestations, i.e. including the blind geothermal systems. This work includes information of the occurrence of recent volcanism (age less than 2 Ma), geological structures, seismic activity, shallow Curie Point Depth, surface heat flow, crustal thickness, hydrothermal manifestations (hydrothermal alteration, thermal fluids discharge, etc.). Data integration is performed using a “Knowledge driven” model with three different geothermal play models producing play fairway evaluations. The presence of several areas with high favorability was identified to lead future detailed exploration in the field.

How to cite: Macedo Serrano, E. and Prol Ledesma, R. M.: GIS-based analysis for regional exploration in the geothermal province of intraplate volcanism in the Center of Mexico, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8945, https://doi.org/10.5194/egusphere-egu23-8945, 2023.

vERE.3
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EGU23-10434
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Paola Anahi Olmedo Velazquez, Mariana Patricia Jácome Paz, Ana Laura Silva López, and Rosa María Prol Ledesma

During the geothermal prospecting and exploration stages, different interests may arise that motivate a socio-environmental conflict over the use of the resource. To prevent this, it is important to have a social management plan and consider cultural values within the exploration stages. The objective of this project is to evaluate the social impacts of the implementation of direct use in the Los Baños geothermal zone, in the intraplate volcanism province of eastern Mexico; as well as to identify the main actors of the territory and their perception of the geothermal resource. To do this, semi-structured field surveys were implemented, and the evaluation format required for larger energy projects (in Mexico) was adapted to identify local aspects of the social dimension.

The main results are identification of actors with greater cultural weight and influence in local decision-making, identification of the existence of a socio-environmental conflict linked to mining in the area, identification of the type of direct geothermal use that can be implemented with greater feasibility (social and technical) in the area, a constant dialogue with the managers of the territory and the joint approach of later stages for the social acceptance of the project.

Acknowledgement

Project PAPIIT-UNAM IA100921 Exploración geotérmica en el Oriente de la Faja Volcánica Transmexicana.

Project PAPIIT-UNAM   IA102123 Exploración avanzada en Los Baños, Veracruz para usos directos de la energía geotérmica.

How to cite: Olmedo Velazquez, P. A., Jácome Paz, M. P., Silva López, A. L., and Prol Ledesma, R. M.: Socio-environmental exploration and evaluation of social impacts for direct geothermal uses in Los Baños, Veracruz, Mexico., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10434, https://doi.org/10.5194/egusphere-egu23-10434, 2023.