Orals: Fri, 2 May | Room -2.43
High-quality maps of the geothermal gradient are essential when assessing the geothermal potential of a region. However, determining geothermal potential is a challenge in regions where direct measurements of in situ temperature and thermal property information are sparse (e.g. Ireland). Significant risk reduction is required to understand the heat resources before they can be fully exploited. Furthermore, individual geophysical methods are sensitive to a range of parameters, not solely temperature.
We determine the geothermal gradient by inverting seismic, in addition to other geophysical, lithological and petrophysical input datasets, directly for temperature. The temperature maps obtained for Ireland so far are within error of direct borehole temperature measurements, providing confidence in the results (Chambers et al. EarthArXiv 2024 and in review). We further develop the joint geophysical-petrological thermochemical workflow used by introducing lithology and transient thermal effects to the inversion. Additionally, gravity data will be integrated into the island scale model to refine the 3D crustal structure, and hence the subsurface temperatures.
We initially focus on new subsurface temperature models of Ireland with uncertainty where the multi-parameter output models fit the input data and reveal the thermal structure within the crust and mantle, including the upper-crustal geothermal gradient. We then will look at the new applications of the methodology at the local scale, in particular at Krafla, Iceland, for a local geothermal powerplant application and the integration of melt to the inversion. The new workflows have potential, to be used as a resource to investigate geothermal regions worldwide.
How to cite: Chambers, E., Owusu, B., Fullea, J., Kiyan, D., Raine, R., Blake, S., and Bean, C.: Joint geophysical-petrological-lithological inversion to determine geothermal potential and subsurface temperature, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6881, https://doi.org/10.5194/egusphere-egu25-6881, 2025.
Characterising the thermal state for geothermal assessment is important to highlight potentially interesting areas. We tested an approach based on stochastic modeling in the western sector of the Po basin. A new thermal database was created by collecting data from hydrocarbon wells, bottom hole temperatures (BHT) and temperatures from drill stem tests (DST). To identify areas with potential geothermal resources, we interpolated data using an original algorithm based on Gaussian simulations producing a 3D temperature field model. This led to generated temperature contour maps at different depths and along selected geological cross-sections. The stochastic modeling identified the area west of Milan as having the highest geothermal potential (temperatures about 180 °C at about 6 km depth). The results of the stochastic modelling were validated with 1D geothermal modelling of the deeper boreholes along the cross-sections. 1D models relied on thermophysical properties (thermal conductivity, volume heat capacity, density and porosity) measured in the laboratory on core samples extracted from the wells, and radiogenic heat production values inferred from gamma-ray logs. Thermal conductivity was inferred using an indirect approach that considers the temperature dependence of the matrix, the pore-fluid conductivity, and the porosity variation with depth. 1D thermal modelling assumes a steady-state purely conductive thermal regime. Geotherms and surface heat-flow estimations for each well were produced by minimising the root mean square error (RMSE) between the calculated temperature and the observed temperature corrected for the drilling mud circulation. The 1D thermal calculations and the temperatures inferred from the stochastic model are in good agreement, but the presence of outliers can lead to important deviations for the stochastic model. The average differences between the temperature profiles of the two models range from 0 to 10 °C, but in particular case reaches 15 °C. In general, in the case of a relatively simple structural setting, as it occurs for the selected cross-sections mainly characterised by horizontal strata, the stochastic model can provide a reliable picture of subsurface temperature distribution since thermal refraction effects are likely negligible.
How to cite: Nanni, T., Chiozzi, P., Miola, M., Gola, G., Verdoya, M., and Vetuschi Zuccolini, M.: Stochastic modelling for identification of potential geothermal resources, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9143, https://doi.org/10.5194/egusphere-egu25-9143, 2025.
The Carboniferous basins in Ireland are rich in fractured carbonate rocks, which present significant potential as geothermal reservoirs. The National Geothermal Database (NGD) project, supported by Geological Survey Ireland, aims to evaluate this potential by developing a comprehensive 3D geological model and assessing geothermal resources. This evaluation includes petrophysical modelling of heat in place (HIP) and heat recovery, with particular attention to permeability enhancements from secondary fracturing and dolomitization related to fault zones.
The 3D model integrates an extensive dataset, including over 50,000 boreholes, 250,000 well tops, 2D seismic reflection data, geophysical surveys, and geological maps. Covering an area of 200 × 200 km, the model incorporates over 180 faults and six stratigraphic horizons, constrained at a high grid resolution (250 × 250 m). Fault analysis, including detailed displacement analysis, reveals that the basins' regional structure is dominated by NE-SW-oriented normal faults, with displacements exceeding 500 m, forming north- and south-dipping half grabens. A polarity shift is observed across the region: in western Ireland, the half grabens are primarily associated with north-dipping faults, while south-dipping faults dominate in the east. This structural variation significantly influences the spatial distribution of geothermal reservoirs, with Lower Carboniferous limestone exceeding 1 km depth located in the hanging walls of these half grabens.
Heat in place (HIP) is calculated using upscaled petrophysical properties—such as density, thermal conductivity, porosity, and heat capacity—derived from measurements and literature for each modelled formation. Temperatures are estimated based on formation-specific thermal conductivities and a uniform heat flow of 70 W/m². Recoverable heat is determined as a fraction of HIP, calculated for various intervals of interest (deep geothermal reservoirs up to 2 km, shallow reservoirs up to 200 m, or specific reservoir units). A recovery factor of 5% is applied outside fault zones, with higher values assumed within fault zones to account for enhanced permeability due to increased fracturing and dolomitization, as observed in outcrops and core data. The volume of the damage zone, defining areas of enhanced recovery, is estimated using fault scaling properties linking displacement and fault zone thickness and a probabilistic approach to account for fault zone thickness variability. The calculated recoverable heat provides site-specific insights into geothermal energy potential and suggests that Carboniferous Limestone reservoirs could play a key role in meeting regional heat demands and make a substantial contribution to Ireland’s net-zero carbon emissions target by 2050. More broadly, this study underscores the importance of incorporating structural modelling to assess resource availability and provides a valuable template for integrating fault zone characteristics into geothermal initiatives.
How to cite: Roche, V., Rodriguez-Salgado, P., Torremans, K., Farrell, C., McCormack, C., Fredericks, L. D., Othen, H., Watson, E., Walsh, J., and Dunphy, R.: Basin scale structural modelling for assessing geothermal potential of fractured carbonates and fault zones in Ireland's Carboniferous Basin., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2497, https://doi.org/10.5194/egusphere-egu25-2497, 2025.
In this study, we conduct a multi-disciplinary study, including geophysics, geochemistry, and geology, with help of tens of previously drilled exploration wells, to reconstruct geothermal geological models at the shallow 3-5 km, for a geothermal exploration project in the Tatun volcano area, northern Taiwan. Our reconstructed geological profiles show that the Tatun volcanoes have a ~1-2-km thick of lava flows and pyroclastic deposits, erupted on top of the 6-8-km-thick fold-and-thrust belt of Miocene sedimentary rocks. The seismic velocity imaging indicates a likely main magma reservoir of high anomaly of Vp beneath the Tatun at the depths of 8-15, with an estimated volume of ~250-300 km3.
Incorporating the regional geology with the newly acquired magnetotelluric (MT) results, we found three high-resistive areas at different depths, which we tend to interpret as possible “heat bodies”. Surrounding these three high-resistivity areas, there exists overlying low-resistive zones or layers, which we interpreted as “cap rocks” and the potential geothermal reservoirs in-between the “cap rocks” and “heat bodies”: 1) two shallow reservoirs, at the depth of 600-1200 m (downhole temperature of 150-250°C), and 2) a deeper reservoir, at the depth of ~ 2-3 km, seemingly in the uppermost basement of quartz-rich sandstone, underneath low-resistive lobs.
At least four high micro-seismicity zones with cylinder shape are interpreted as conduits of hot fluid derived from deep over-pressured zones, either along the frontal thrust of the Jinshan fault (at the depth of ~2 km), or the outer edge of the fluid saturated magma reservoir around 4-6 km depth, which is also of potential for “super-hot or super-critical geothermal” exploration.
How to cite: Lee, J.-C., Chen, C.-C., Huang, H.-H., Lin, C.-H., Hase, H., Song, S.-R., Lu, Y.-C., Yeh, E.-C., Kuo, L.-W., Mu, C.-H., Kuo, S.-T., Chan, Y.-C., Chen, Y.-G., and Chung, S.-L.: Reconstructing geothermal geological models by combining geophysical, geochemical and geological studies in Tatun volcanoes area, Northern Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4623, https://doi.org/10.5194/egusphere-egu25-4623, 2025.
The Pannonian part of Croatia has favorable geothermal characteristics that promote the development of natural thermal springs (temperatures up to 65 °C) in around 20 localities. These waters have been used for millennia and are the basis for tourism and health care centers. Due to an increase in the water demand, higher quantities were abstracted threatening the availability of the thermal resources. These thermal springs are generally part of intermediate scale, topographically driven, hydrothermal systems fed by local meteoric waters with: i) recharge areas in the mountainous hinterlands of the springs, ii) Mesozoic carbonate geothermal aquifers with high secondary porosity and permeability, and iii) discharge areas with favorable structural settings increasing the bedrock fracturing and the permeability field.
The continuous functioning of such systems depends on a delicate balance between: i) infiltration, ii) groundwater flow velocities and precipitation/dissolution processes in the reservoir, iii) active tectonics maintaining the permeability field, iv) heat flow from the deeper parts of the crust, and v) natural outflow of thermal waters and/or their exploitation. In order to maintain this balance and use thermal water resources in a sustainable manner, a system-level understanding is needed. The HyTheC project promotes a multidisciplinary approach (structural geological, hydrogeological, geothermal, hydrogeochemical, geophysical, and remote sensing investigations) to: i) propose a conceptual model of the system, ii) perform a 3D geological model of the study area, iii) conduct hydrogeological and thermal parametrizations of the main hydrostratigraphic units, and iv) perform numerical simulations of the system functioning in undisturbed natural conditions and with different extraction scenarios. The methodology was tested in three pilot areas in Croatia where thermal water is used, but the levels of knowledge on the systems were quite different.
The Daruvar hydrothermal system was the most investigated. The investigations were conducted to detail the regional and local structural settings promoting the thermal water flow and to quantify the impact of geological and physico-chemical processes on the development of the system through 3D numerical simulations. The Topusko hydrothermal system was poorly investigated, and even the recharge area was not determined. The multidisciplinary approach was applied for detailed hydrochemical and hydrogeological characterizations and for the physical validation of the proposed conceptual model through 2D numerical simulations. The Hrvatsko zagorje hydrothermal system is the largest one, with a diffuse outflow of thermal water in several thermal spring areas. Since previous investigations were available, a 3D regional geological reconstruction of the study area was conducted, while numerical simulations of fluid flow and heat transport are under development.
The increase in thermal water utilization is foreseen by many European and Croatian strategic documents regulating energetics, tourism, and environmental protection. The results of the HyTheC project highlight the importance of conducting multidisciplinary investigations for the characterization of hydrothermal systems. The obtained results will serve to protect these economically and culturally important sites preserving them for future generations.
Acknowledgment: This research was funded by the HyTheC project of the Croatian Science Foundation, grant number UIP-2019-04-1218.
How to cite: Borović, S., Pola, M., Pavić, M., Briški, M., Kosović, I., Frangen, T., Urumovic, K., Matoš, B., Pavičić, I., Terzić, J., and Cacace, M.: Multidisciplinary Approach to Conceptual Modelling of Hydrothermal Systems in Croatia (HyTheC), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17214, https://doi.org/10.5194/egusphere-egu25-17214, 2025.
In the context of the energy transition, the characterization of deep geothermal reservoirs represents a major challenge for the development of decarbonized energy sources. The Upper Rhine Graben has a significant geothermal potential and is widely underexploited. Given the significant lithium concentrations recently identified in geothermal brines, understanding reservoir properties and their spatial distribution is crucial to optimize the exploration and exploitation of these resources.
This study focuses on the comparative analysis of reservoir properties in Buntsandstein sandstone from various boreholes in the Upper Rhine Graben. Our approach compares sedimentary lithologies below the basement unconformity from the EPS1 well in eastern France with the Sexau and Heidelberg wells in western Germany. This comparison enables the investigation of the impact of different burial histories on reservoir properties and contrasts the central graben position with its margins. The methodology employed combines several complementary measures. Detailed sedimentological analysis enables the characterization of facies, deposit environments, and their distribution. The petrophysical study of porosity, permeability, density, and thermal conductivity is coupled with diagenesis analysis to understand the evolution of the pore network. Quantitative mineralogy analyses complete the characterization of diagenetic phases. Additionally, LIBS analyses were performed top map lithium distribution and identify Li-bearing minerals within the sample. Spatial mapping of lithium content reveals its distribution patterns and mineralogical associations, providing new insights into the relationships between reservoir properties and lithium occurrence in the geothermal system.
The results show the boreholes at the graben margin exhibit better-preserved reservoir properties with average porosities and permeabilities. In contrast, the EPS1 sedimentological cover shows a significant reduction in these properties due to greater mechanical compaction and more intense cementation. These findings contribute to a better understanding of sandstone reservoir evolution in graben systems and provide valuable insights for subsurface geothermal resources assessment in similar geological contexts. Furthermore, the characterization of lithium distribution, patterns open perspectives for potential co-production of geothermal energy and lithium resources.
How to cite: Cosme, P., Bossennec, C., Geraud, Y., Malartre, F., Diraison, M., Vidal, J., and Haffen, S.: Evolution of Reservoir Properties in Buntsandstein Sandstones: A Comparative Wells Analysis from the Upper Rhine Graben, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20439, https://doi.org/10.5194/egusphere-egu25-20439, 2025.
The geological structure of a region critically influences the occurrence and distribution of geothermal resources. This study elucidates the structural controls on geothermal reservoirs in the Boye area of the Jizhong Depression, central North China Craton, using gas geochemistry, controlled-source electromagnetics, geophysical well logging, and structural analysis. The primary faults in Boye are NE-SW trending normal faults formed in an extensional regime, with NW and SE dips, steeper near the surface, and gentler at depth. Fault orientations vary locally due to deep structural influences. Angular unconformities are identified between the Wumishan Formation (Jixian System) and Kongdian Formation (Paleogene), and between the Dongying Formation (Paleogene) and Guantao Formation (Neogene). Local parallel unconformities exist between the Kongdian and Shahejie Formations (Paleogene), and between the Shahejie and Dongying Formations. Structural attributes and fault properties significantly control geothermal resource enrichment. The deep carbonate geothermal reservoirs in Boye primarily comprise Jixian System Wumishan dolomite, including chert-banded, muddy sandy fine-grained, and stromatolitic dolomite, characterized by abundant fractures and cavities. Geothermal resources are governed by an integrated system of source, migration, reservoir, and cap structures. Source structures control crust-mantle heat flow. Migration structures, including faults and unconformities, act as conduits for water and heat transfer. Reservoir structures encompass fractures and cavities, providing storage space. Cap structures facilitate atmospheric precipitation infiltration, though local faults can partially compromise insulation. This comprehensive structural analysis establishes a mechanism linking geological structures to geothermal resource development in Boye.
How to cite: Dai, P., Wu, K., Wang, S., Zheng, S., and Zhang, Z.: Study on structural controlled geothermal reservoirs across the Boye Area, central North China Craton, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2106, https://doi.org/10.5194/egusphere-egu25-2106, 2025.
Geothermal energy plays a crucial role in the global energy transition. Tuscany hosts Italy’s active geothermal fieds of Larderello-Travale where geothermal power generation was pioneered in the early 20th century. The region is characterized by an anomalously high heat flow rate of up to 1000 mW/m2 and extreme geothermal gradients (locally exceeding 150°C/km). These conditions drive regional-scale hydrothermal circulation where temperatures can exceed 500°C at about 3 km depth. While the exploration of deep horizons within established steam fields remains vital for identifying new targets with reservoirs characteristics, the investigation of unexplored regions is equally crucial to expand geothermal exploitation in different geological contexts and to understand the broader system dynamics. This study examines the tectonic history of the northern Apennine belt in the understudied Roccastrada-Ribolla basin and evaluates the seismic signature of potential deep productive targets therein.
We applied the nodal ambient noise tomography (NANT) method to generate a high-resolution shear-wave velocity (Vs) model of the upper crust. The method leverages depth-sensitive surface waves that dominate virtual seismograms estimated from ambient noise cross-correlation. In addition, the joint inversion of Rayleigh and Love wave dispersive properties provides higher resolution information about the distribution of seismic velocity anisotropy in the subsurface. We use continuous seismic data from a dense local network of 189 three-component short-period geophones (250 Hz sampling rate) deployed for one month during June-July 2023. The critical step of surface wave dispersion curves extraction is treated automatically as a semantic segmentation problem through a deep convolutional neural network approach while a two-step inversion scheme is used to retrieve the 3-D shear-wave velocity model: (non-)linear 2-D travel-time tomography inversions, followed by a trans-dimensional Markov chain Monte Carlo probabilistic search algorithm for 1-D Vs depth inversions. The jointly inverted 3-D Vs model for Rayleigh and Love waves reveals structures consistent with local basin geology and aligns with features identified by deep active seismic exploration profiles made in the central Mediterranean and Italy (CROP Project). This promising exploration campaign not only presents new prospects for the exploitation of deep geothermal systems but also advances our understanding of complex tectonic settings while demonstrating the efficacy of rapid, semi-automated, and cost-effective seismic imaging for industry applications.
How to cite: Stumpp, D., Cabrera-Pérez, I., Savard, G., Michailos, K., Amir Jiwani-Brown, E., Muñoz Burbano, F., Porras Loria, J., Borotau, S., Montanari, D., Lanari, R., Papeschi, S., Bonini, M., and Lupi, M.: Joint Rayleigh and Love wave nodal ambient noise tomography in the Northern Apennines hinterland, Roccastrada-Ribolla basin, Italy., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18875, https://doi.org/10.5194/egusphere-egu25-18875, 2025.
A new enhanced geothermal system (EGS) is currently being engineered in the Haute-Sorne region in the Swiss Jura. Passive seismic imaging is conducted in the framework of the project as a viable basement-resolving and affordable technique to study subsurface structures at depths where active seismic surveys face limitations. We deployed 686 three-component seismic nodes with an inter-station spacing of approximately 300 m. This network spans a radius of about 15 km around the well and recorded the seismic ambient wavefield for one month in February 2024.
This study focuses on the reconstruction of diving P-waves from the recorded seismic ambient wavefield. We analyze data from 8 random days and apply the cross-coherency approach to estimate the impulse response between station pairs within the frequency band of 0.5–2.5 Hz. During processing, polarization characteristics are utilized to separate and enhance the P-wave signal from Rayleigh waves. Subsequently, we apply a bin-stacking method to compute a 1D P-wave retrieval with improved signal-to-noise ratio. We use this 1D P-wave as an example to apply a selected filter to individual traces and isolate the empirical Green’s functions containing the P-wave energy. 3D P-wave arrivals are automatically picked based on their coherent moveout.
Using these phase arrivals, we perform a travel time 3D tomography to estimate the P-wave velocity model in the Haute-Sorne region. The estimated P-velocity model reveals detailed information about shallow subsurface structures. A comparison with the S-wave velocity model, well-log data, and known geological structures demonstrates an agreement with the available complementary data and encourages the applicability of the P-wave tomography as a viable tool for geothermal prospecting. In the next phase, the combined analysis of P- and S- velocities will enable the estimation of the P-to-S velocity ratio, a key parameter for characterizing the geothermal reservoir.
How to cite: Riahi, A., Savard, G., Cabrera-Pérez, I., Koulakov, I., Sfalcin, J., and Lupi, M.: Body Wave Seismic Noise Tomography and Subsurface Characterization for Geothermal Exploration, the Haute-Sorne EGS project, Switzerland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4916, https://doi.org/10.5194/egusphere-egu25-4916, 2025.
With the global transition to sustainable energy, Enhanced Geothermal Systems (EGS) have garnered increasing attention as a promising source of clean and renewable energy. EGS utilizes hydraulic fracturing to enhance reservoir permeability by initiating and expanding fractures, thereby enabling efficient exploitation of hot dry rock resources. However, hydraulic fracturing is often accompanied by microseismic events or small-scale earthquakes, posing challenges to project safety and economic feasibility. This problem has become a focal point of recent research. Significant case studies have been conducted in regions such as Pohang, South Korea; the Cooper Basin, Australia; Basel, Switzerland; Insheim, Germany; Fenton Hill, USA; as well as in China's geothermal fields, including Qabuqa in Qinghai Province, Huashadong in South China, and Matouying in North China. Despite variations in injection strategies and operational conditions, all these projects have encountered risks of induced seismicity. The mechanism of these seismic events varies depending on the lithology and tectonic setting of the region and deserves further exploration.
Case studies reveal that larger-magnitude-induced earthquakes are predominantly associated with granitic reservoirs and commonly linked to well-developed strike-slip faults. These events are primarily triggered by the activation of pre-existing faults due to increased pore pressure from fluid injection. Specifically, elevated injection pressure reduces fault friction, leading to slip instability. These findings provide valuable insights for the prediction and mitigation of induced seismicity during artificial fracturing. However, sedimentary reservoirs exhibit lower rates and magnitudes of induced seismicity, though their triggering mechanisms warrant further investigation.
In this study, regression analysis was employed to identify key factors influencing the maximum magnitude of induced seismic events, and the data are mainly derived from the study areas of typical hot dry rocks around the world. The analysis focused on parameters such as fault length, maximum injection pressure, maximum injection rate, total injected fluid volume, and fracturing depth. The results show that there are significant differences in the influence of different factors on the maximum magnitude under different lithological conditions. Dual-parameter regression models reveal that the combination of fault length and total injected fluid volume shows higher correlation with seismicity in sedimentary reservoirs, whereas the combination of maximum injection pressure and injection rate is more relevant for magmatic rock. A comprehensive analysis of both sedimentary and magmatic reservoirs demonstrates that injection pressure and fault length are the primary parameters controlling the maximum magnitude of induced seismicity. Dual-parameter models exhibit superior predictive capabilities across lithological conditions, offering robust theoretical support for future seismic risk assessments.
Acknowledgment
This study was supported by the Natural Science Foundation of China (42430808).
How to cite: Yu, H. and Chen, Y.: Dual-parameter Regression Models for Assessing the Risk of Induced Seismicity in Enhanced Geothermal Systems (EGS), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2213, https://doi.org/10.5194/egusphere-egu25-2213, 2025.
Geothermal energy is a low-carbon energy solution obtained by harnessing the heat of the Earth’s interior, stored in rocks and groundwater. Despite its advantages as competitive renewable energy, geothermal development is full of challenges including tubing scaling risk due to important pressure (P) and temperature (T) changes in thermal fluids during the geothermal loop. Geochemical models are developed to determine the geochemical processes that control scaling processes, allowing creation of efficient geothermal plants and scaling risk evaluation for new and existing facilities. Four major scaling minerals such as silicates, carbonates, sulfides, and oxides, have been reported to dominate the geothermal environment. Among them, the silica scaling is one of the biggest problems occurring in many geothermal fields worldwide.
In this study, a PHREEQC geochemical model is carried out to evaluate the mineral scaling risk associated to a new potential geothermal loop using water from a carbonate reservoir. The effect of gradual pressure and temperature changes on the evolution of the water chemistry is assessed by defining (thermodynamic) equilibrium simulations during the three steps of the geothermal loop: (i) P decrease from 285 bar to 18 bar in the isothermal water pumping, (ii) T decrease from 107.5 °C to 40 °C in the isobaric cooling, and (iii) both P and T increase up to 285 bar and 107.5 °C, in the re-injection to reservoir. The amount of mineral precipitation at a given location in the tubing is provided by PhreeqC in kg/L of water. Hence, the rate of mineral precipitation at this location is calculated by multiplying this amount by the water flow rate (L/d).
During the pumping, no silicate and sulphate precipitation is revealed. However, calcite precipitation occurs, reaching the highest amount of precipitation at the lowest P. Fe-bearing phases also precipitate during the pumping due to the high Fe concentration released from tubing corrosion. Different precipitation reactions are revealed in the cooling where no carbonate, but barite precipitation takes place during the process, reaching the highest amount of precipitation at the lowest T. Even if barite precipitates at any T (from 107.5 °C to 40 °C) within the whole cooling, it does not show the highest rate of precipitation. Despite chalcedony precipitates in a closer T window (from 55 to 40 °C), it reaches a higher precipitation rate than barite (65,1 kg/d for chalcedony versus 11,4 kg/d for barite). The last step of the geothermal loop (re-injection to reservoir) does not show any possible mineral precipitation.
In addition to the ‘batch’ equilibrium simulations presented here, we plan to improve our model by performing reactive transport simulations in which scaling mineral precipitation kinetics as well as water flowing in the tubing will be considered.
How to cite: Garcia Rios, M. and Jacquemet, N.: Geochemical modelling to evaluate mineral scaling risk in a geothermal loop., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16336, https://doi.org/10.5194/egusphere-egu25-16336, 2025.
This study investigates optimal well configurations for sedimentary geothermal development in tilted strata, using NS mining area in western Taiwan as a case study. A numerical model was constructed using CMG STARS simulator to analyze a doublet system in the first sandstone layer, with horizontal wells designed following DEEP Corporation's "ribcage" well field concept from the Williston Basin development.
The base case model utilized one production well and one injection well, each with 1,000-meter lateral sections and 750-meter well spacing, positioned at the same depth and operating at 100 tons/hr for a 20-year period. Sensitivity analyses were performed on well positioning and production rates to determine the optimal system design. Specific constraints included maintaining bottom-hole pressure variations within 20% and achieving stable wellbore temperature for sustainable operations.
Results demonstrate that positioning injection wells at shallower depths than production wells was detrimental, leading to accelerated temperature decline and reduced facility capacity. Conversely, deeper injection well placement shows enhanced performance, particularly at higher production rates. At production rates exceeding 100 tons/hr, the configuration with deeper injection well placement achieved optimal results, reaching a 20-year average facility capacity of 1.325 MWe.
The study concludes that placing injection wells deeper than production wells in tilted strata provides superior thermal performance and facility capacity, especially at higher production rates. These findings offer practical guidelines for well design in similar geological settings, contributing to the advancement of sedimentary geothermal development strategies.
How to cite: Chang, Y.-M., Wu, C.-Y., Tang, T.-K., Hsu, W.-C., Yang, K.-M., and Hsieh, B.-Z.: Well Configuration Study for Sedimentary Geothermal Development in Tilted Strata: A Case Study in Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5773, https://doi.org/10.5194/egusphere-egu25-5773, 2025.
The shift from fossil fuels to renewable energy sources is a growing trend. Since geothermal energy is located beneath oil and gas wells, converting abandoned oil and gas wells into geothermal wells is a promising option. Potential candidate wells include dry holes from oil and gas exploration or wells in depleted reservoirs. There exists a knowledge gap in the engineering of well conversion, specifically regarding the factors influencing the performance of geothermal wells [1].
This study provides a comprehensive evaluation of the viability of abandoned oil and gas fields for geothermal energy extraction in the Volve field in the North Sea. By integrating petrophysical data, including porosity and permeability, and leveraging advanced statistical and computational techniques. The research aims to enhance the understanding of geothermal reservoir characterization and dynamic modeling. Using Equinor’s publicly accessible dataset, the study incorporates stochastic simulation [2], principal component analysis (PCA), and clustering techniques to identify patterns, optimize reservoir management, and refine energy extraction models. The research is also keen to explore the integration of additional petrophysical and geomechanically parameters, as well as advanced technologies like Enhanced Geothermal Systems (EGS) [3] and carbon capture and storage (CCS), to further enhance geothermal energy production in similar settings.
The statistical analysis of porosity and permeability reveals critical insights into their collective influence on reservoir performance. Descriptive statistics demonstrate a mean porosity of 0.170 and permeability of 509.59 mD, with minimal variability in porosity but significant heterogeneity in permeability, as evidenced by a wider standard deviation.
The integration of these findings into tNavigator software enabled the construction of a dynamic geothermal reservoir model. The model simulated fluid flow dynamics, temperature distribution, and energy recovery potential over a 20-year operational period. Results demonstrate sustained energy production, with cumulative enthalpy reaching 41,376.4 MWh, validating the feasibility of geothermal energy extraction from the Volve field.
In conclusion, this research highlights the potential of abandoned oil and gas fields as viable sources of geothermal energy. By employing advanced statistical methods and dynamic modeling tools, the study provides actionable insights for optimizing geothermal reservoir performance.
References
[1] Zhang, P., and B. Guo. "Fluid Temperature of Geothermal Energy Wells Converted from Abandoned Oil/Gas Wells." Paper presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, October 2023.
[2] Soares, A., 2001, Direct sequential simulation and co-simulation: Mathematical Geology, 33, 911–926, doi: 10.1023/A:1012246006212.
[3] Garcia, J., et al. (2022). “Integrating Carbon Capture and Storage with Geothermal Energy Production in Abandoned Oil Fields.” Energy Procedia, 135, 567–578.
How to cite: Sherif, H., Bennour, Z., Soares, A., and Rivas, S.: Viability of Abandoned Oil and Gas Fields in for Geothermal Energy with Focus on the Volve Field, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20594, https://doi.org/10.5194/egusphere-egu25-20594, 2025.
Posters on site: Fri, 2 May, 08:30–10:15 | Hall X4
Geothermal energy, a clean, continuously available and sustainable energy source, will help boost the current renewable energy supply and, simultaneously, reduce the dominant contribution of fossil fuels to the total energy supply in Italy [1]. Efficient exploitation of this resource, however, requires a characterization of the subsurface region, through integration of multi-parameter datasets, to mitigate the risks of drilling unsuccessful geothermal wells.
The InGEO project (Innovation in GEOthermal resources and reserves potential assessment for the decarbonization of power/thermal sectors, www.ingeo.cnr.it) seeks to develop an innovative exploration workflow integrating geological, geophysical and petrophysical datasets. It focuses on the northern sector of the Northern Apennine buried-structures belonging to the Romagna and Ferrara Folds (RFF), where a thermal anomaly attributable to deep fluid circulation within the deep-seated Mesozoic carbonate sequences, was identified [2].
With an ongoing study focusing on the reconstruction of a 3D geological model of the RFF region [3], this study develops the research by jointly interpreting previous geophysical datasets [4-5] geographically constrained within the RFF region. The novelty consists on the application of a machine learning algorithm for jointly re-interpreting geophysical datasets. The similarities among the geophysical datasets within the RFF are classified by applying the Fuzzy c-means method, which uses the Euclidean distance measure. The findings include the 3D spatial distribution of derived classes and are validated with the 3D geological model of the RFF [3] and laboratory data obtained on rock samples analyses [6].
The resulting 3D geophysical model contributes to the delineation and constraint of shallow and deep structural features within the RFF. This information will be used as input parameters for the development of a thermal model and the implementation of an open-source and web-based GIS tool that will assess the deep geothermal resource potential for both hydrothermal resources and closed-loop deep heat exchangers solutions in Italy, but with potential to extend the approach in different geological contexts. The workflow of InGEO project will be used as a decision support system for developing geothermal projects in Italy.
InGEO is a PRIN 2022 PNRR Project and has received funding from the European Union, Next Generation EU.
References
[1] International Energy Agency (IEA) Italy 2023 Energy Policy Review. https://www.iea.org/reports/italy-2023
[2] Pasquale et al., 2013. Evidence for thermal convection in the deep carbonate aquifer of the eastern sector of the Po Plain, Italy. Tectonophysics 594, 1-12.
[3] Cortassa et al., 2024. Integrated geological modelling for assessing geothermal potential in the Romagna and Ferrara Folds (Italy). 43° National Conference GNGTS, Bologna, 11-14 February 2025.
[4] Nouibat et al., 2023. Ambient-noise wave-equation tomography of the Alps and Ligurian-Provence basin. J. Geophys. Res., 128, e2023JB026776.
[5] Zahorec, et al., 2021. The first pan-Alpine surface-gravity database, a modern compilation that crosses frontiers, Earth Syst. Sci. Data, 13, 2165–2209.
[6] Slupski et al., 2025. The importance of measuring thermal and acoustic properties on rock analogues in geothermal potential assessment studies: the example of Northern Apennines Triassic carbonate platform and underlying basement rock. 43° National Conference GNGTS, Bologna, 11-14 February 2025.
How to cite: Basant, R., Tesauro, M., Cortassa, V., Gola, G., Nanni, T., Galgaro, A., and Manzella, A.: Machine Learning-Based Joint Interpretation of Geophysical data for the geothermal potential assessment in the Romagna and Ferrara Folds (Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12018, https://doi.org/10.5194/egusphere-egu25-12018, 2025.
Geothermal energy is emerging as a promising renewable power source in the global energetical transition toward a clean energy future. The role of shallow and deep tectonic structures on fluid circulation and heat transfer is of primary importance to better target high-temperature geothermal reservoirs. In extensional context, the complexity of geothermal processes results from the coexistence of multiple structures whose activity evolves through time: normal to oblique faults, detachments and transfer zones. This complex structural setting leads to major questions: What are the main pathways driving fluid flow and heat transfer in high-temperature geothermal systems? What is the plumbing of the system at depth? What is the origin of geothermal fluids and recharge potential of the system? To address these issues, we propose a coupled study of an active system, i.e. the Larderello geothermal system (Tuscany, Italy), and its fossil, exhumed equivalent, i.e. the Elba Island and the Boccheggiano area (Italy). This region is located in a back-arc extensional context, following the eastward retreat of the west-verging Adriatic slab that started about 35 Ma ago. Deformation, that migrates eastward with the slab retreat, has been accommodated by low-angle detachments and associated normal faults. Such structures allowed the exhumation of metamorphic core complexes (MCCs) and the emplacement of plutonic bodies whose ages decrease eastward. Therefore, Elba Island with its exhumed detachments and MCC can be considered as a fossil equivalent of the active Larderello geothermal system. Through this project, we propose a Thermo-Hydro-Mechanical (THM) model of the Larderello geothermal system constrained by the available geophysical and geochemical data. Additional constraints at depth will be then provided by fieldwork observations (structural, mapping, sampling) and laboratory analysis (isotopes, elemental composition, fluid inclusion) on mineralized fault zones mainly from Elba Island. The disclosed part at EGU 2025 will focus on the preliminary modelling activities of Larderello. Firstly, a geological model is built with the PETREL software based on the available borehole data and interpreted seismic lines or cross-sections, which enables to display the 3D lithostratigraphic sequence and the structural geometries at depth. It highlights the complexity of this system related to boudinage favored by low-angle normal faults, which caused important thickness variations (up to disappearance) of some geological units through space, as well as important normal fault offsets, and flat horizons associated to shear zones at depth. Subsequently, the THM numerical model is solved with the COMSOL Multiphysics software by employing the above-mentioned geological model as the main geometrical framework. Presented numerical results focus on the plumbing of the system (different types of faults and their crosscutting relationships) and its role on heat transfer and fluid flow processes. Furthermore, different water recharge scenarios are also investigated. The chosen physical parameters involved in fluid flow, heat transfer and poroelasticity phenomena together with their implications on the numerical solutions are discussed. This on-going and multidisciplinary work participates to assess the geothermal potential, identify new exploitable areas and estimate the lifetime of high-temperature geothermal systems, fitting the global context of carbon-free energy development.
How to cite: Lagardère, C., Do Couto, D., Verlaguet, A., Jolivet, L., Leroy, S., and Gola, G.: Thermo-Hydro-Mechanical modelling of the Larderello geothermal system, Tuscany, Italy: Emphasis on the role of tectonic structures, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17687, https://doi.org/10.5194/egusphere-egu25-17687, 2025.
Magmatism is an important driver of topographic change. However, our understanding of its long-term impact on topographic evolution remains incomplete. In the framework of the MIGRATE project, we investigate the potential surface response to magmatic intrusions in the active Larderello-Travale geothermal field, in the northern Italian Apennines. Here, multiple igneous bodies have intruded since the late Pliocene causing at least 500 meters of large-wavelength surface uplift. We combine available stratigraphic information with a new set of morphological analyses and river inversion models to quantify, the magnitude, rate, and spatial distribution of surface uplift throughout over the last 3.5 Ma. In describing the style of the uplift, we report a temporal and spatial correlation between rock uplift pulses and middle crust magma injections.
For the first time in this area, we document the positive feedback between different magma injections and local surface responses (e.g. river incision). We use a surface evolution model to suggest a potential scenario of magma emplacement over time. In this sense, we suggest that at the very beginning, uplift rates were higher to the north of the current thermal anomaly, and only over the last 2 Ma the uplift migrated further south. This could indicate that the deep source of the Larderello-Travale geothermal field might not be precisely located underneath the current thermal anomaly. This would allow undocumented plutons (deep enough such that they are not evidenced by shallow thermal anomalies) to be tracked, leading to more conscious and effective strategies for geothermal exploration.
How to cite: Lanari, R., Bonini, M., Sembroni, A., Papeschi, S., Del Ventisette, C., Smith, A., Lupi, M., and Montanari, D.: Topographic signature of magmatic emplacement: the case of the Larderello-Travale Geothermal area (Northern Apennines, Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7956, https://doi.org/10.5194/egusphere-egu25-7956, 2025.
Seismic activity in Tuscany, Italy, is driven by the interplay between complex tectonics and fluid flow processes. Fluid-driven seismic sequences are typically associated with high-enthalpy geothermal regions, such as the Larderello-Travale Geothermal Field (LTGF). To better understand the regional tectonic setting, we derive a detailed catalogue of earthquake hypocenters and magnitudes from a seismic network consisting of 30 permanent seismic stations from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and 30 temporary stations deployed in Tuscany in the framework of a specific acquisition survey (TEMPEST), during a period of one year (from September 2020 to September 2021).
We applied an automated processing routine including a machine‐learning (ML) phase picker, PhaseNet, and the Gaussian Mixture Model Association (GAMMA) algorithm, a sequential earthquake association and location workflow. We initially obtained nearly 1 million P-phases and 2 million S-phases, yielding around 5k detected events. We then located the events with NonLinLoc and applied quality metrics to filter out potential false detections (22%) and recognize the high-quality solutions, which represented 30% of the initial 5k locations. The high-quality catalogue has been relocated with the Double-Difference software scrtdDD to better constrain earthquake clusters and to improve the robustness of the subsequent analysis of the seismic sources in the region.
We identified a five-day-long sequence of 203 earthquakes with magnitudes Mw ranging from 0.4 to 2.0, oriented NW-SE, north of Monte Amiata (Southern Tuscany). We observe a temporal upward migration of the events between 10 to 5 km depth towards SE. We have obtained seven high-quality focal mechanisms from first-motion polarities by applying a Bayesian approach (Mtfit). Our results suggest the occurrence of a seismic swarm with predominant normal faulting mechanisms and average dipping angles of 50° NE. Our solutions could be associated with a normal fault system that is compatible with the local geology.
How to cite: Porras, J., Michailos, K., Savard, G., Montanari, D., Saccorotti, G., Bonini, M., Del Ventisette, C., and Lupi, M.: Seismicity in central Tuscany, Italy: Insights from a regional seismic deployment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15476, https://doi.org/10.5194/egusphere-egu25-15476, 2025.
Unlocking the geothermal potential of Britain’s Mississippian carbonate platforms (MCP) could significantly advance the UK transition to net-zero carbon emissions. Geothermal energy offers a reliable and clean heat source, yet comprehensive assessments of geothermal resources remain limited, despite the urgency of decarbonization efforts. The MCP, equivalent to Early Carboniferous limestones (ECL), are linked to thermal springs in Bath, Bristol, the Taff Valley (South Wales), and the Peak District (UK). Their bulk permeability, however, is highly variable, with fluid flow largely governed by faults and fractures. While Belgium and the Netherlands have successfully harnessed similar formations for geothermal energy, the MCP in Britain remain underexplored. Limited seismic data and sparse boreholes reaching the top of the MCP highlight the critical need for further investigations.
Our main focus in this presentation addresses the connectivity of the fault and fractures in the MCP,through multi-scale data, to provide valuable insights into geothermal energy potential. This study integrates regional, local, and outcrop-scale data from the MCP. Fault and fracture maps are developed using: (a) seismic reflection data and published geological maps, and (b) fieldwork imagery. In situ stress and pore pressure data are drawn from legacy onshore hydrocarbon wells, wireline logs, British Geological Survey reports, and recent publications. Fault stability analyses, incorporating Normalised slip (Ts) and dilation (Td) tendencies, provide insights into likely fault and fracture behaviour. By addressing uncertainties in input parameters, the study evaluates their implications for geothermal resource exploration.
Key findings in this study include: (a) a detailed characterization of fracture network connectivity and patterns in the MCP, (b) refined understanding of regional-to-local fault-fracture interpretations, and (c) permeability estimates under prevailing stress conditions. The integration of outcrop and subsurface data enhances the reliability of the interpretations, bridging the gap between field observations and geological modelling. Additionally, insights into the role of subsurface stress regimes and their impact on fault stability will provide valuable guidance for optimizing drilling strategies and mitigating operational risks.
How to cite: Aditama, M., Hollis, C., Huuse, M., and Healy, D.: Multi-scale fault and fracture networks of Mississippian carbonate platforms (MCP): implications for extracting geothermal energy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4250, https://doi.org/10.5194/egusphere-egu25-4250, 2025.
The Buda Thermal Karst is characterised by three geographically and geologically separated discharge areas along the Danube in the Buda Hills (Erőss et al, 2012 etc.). These contain lukewarm, lukewarm - warm and warm springs, respectively. This research aims to find an answer to the question of the separation and differences of these discharge areas and their significance in geothermal exploration under the confined Pest side.
Along with the datasets used in previous numerical simulations (Szijártó et al, 2021 etc.), the Supervisory Authority for Regulatory Affairs Hungary (SARA) has made available a new three-dimensional geological model of the study area. This updated model enables more accurate numerical simulations.
In the numerical simulations of the recent study, we use the previous datasets and we are creating five two-dimensional cross-sections by Comsol Multiphysics. The evaluation includes a flow system and temperature analysis that relies on a comparison between model results and on-site measurement data. The primary objectives of the modelling include:
(1) evaluating the connection between lukewarm and warm springs of the Central system and the thermal waters in the deep confined karst areas of Pest
(2) assessing the structural separation of this system from adjacent Northern and Southern areas and its implications for geothermal exploration risks.
This research is directly linked to geothermal risk assessment by testing how numerical model outputs can be integrated into the development of general methodologies for geological risk analysis.
Preliminary findings suggest that the thermal springs of the Buda Thermal Karst Central system are connected to the regional discharge area at the Danube River. This indicates that the most favourable conditions for geothermal utilization can be found in areas near the Danube on the Pest side. However, these areas are also critical for protecting the water of the thermal baths, emphasizing the need to incorporate risk assessment into geothermal planning. The modelling results offer multiple applications concerning data integration. In this research, the theoretical temperature distribution estimated through statistical analysis of the model outputs can be used to predict the performance of geothermal projects and evaluate the geological feasibility of potential developments. This integrated approach highlights the importance of balancing geothermal energy utilization with conserving natural thermal resources.
This research was carried out within the framework of the project RRF-2.3.1-21-2022-00014 of the Climate Change Multidisciplinary National Laboratory.
Supported by the EKÖP-24 University Excellence Scholarship Program of the Ministry for Culture and Innovation from the Source of the National Research, Development and Innovation Fund. Contract number: ELTE/15380/1(2024)
References
Erőss, A., Mádl-Szőnyi, J., Surbeck, H., Horváth, Á., Goldscheider, N., & Csoma, A. É. (2012). Radionuclides as natural tracers for the characterization of fluids in regional discharge areas, Buda Thermal Karst, Hungary. Journal of Hydrology, 426, 124-137.
Szijártó, M., Galsa, A., Tóth, Á., & Mádl-Szőnyi, J. (2021). Numerical analysis of the potential for mixed thermal convection in the Buda Thermal Karst, Hungary. Journal of Hydrology: Regional Studies, 34, 100783, pp.2.
How to cite: Tóthi, T., Mádl-Szőnyi, J., Markó, Á., Csicsek, L. Á., Szilágyi, I., and Szijártó, M.: Connections between Thermal Springs and Deep Geothermal Potential in the Buda Thermal Karst System, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4392, https://doi.org/10.5194/egusphere-egu25-4392, 2025.
The Asal-Ghoubbet Rift is a less-than-one-million-year-old area characterized by both magmatic and tectonic activity. It is underlain by very thin crust and exhibits exceptionally high temperatures at reachable depths, making it highly favorable for geothermal energy development. However, despite the high temperatures, geothermal exploitation in this region faces significant challenges, mostly related to sustainable access to fluids, including generally low permeability, low flow rates, and highly saline fluids. Some of the identified sites have proven unproductive, which can be attributed to a limited understanding of the subsurface geothermal system.
This resource is challenging to evaluate, and a reliable 3D geological model is therefore essential. This paper presents the first static model of the geothermal site in the Asal-Ghoubbet region, which serves as a foundation for numerical simulations. To build the geological model, a combination of well data, surface geological observations, geophysical studies, and structural knowledge was employed. As the data are not equally spread across the considered area, four geological cross-sections, representative of the subsurface structures, were created and used as input data for the modeling. The geometry and properties of the subsurface structures were interpolated using the Discrete Smooth Interpolation (DSI) method, implemented through the SKUA/GOCAD software. The resulting 3D model consists of four main stratigraphic units and 17 normal fault planes aligned parallel to the rift.
Numerical modeling of temperature and fluid circulation was performed using the TemisFlow basin modeling software, which integrated the geometry of the geological model built in SKUA, the lithological fill, and a representation of the lithosphere in the study area. Several scenarios were tested to address uncertainties regarding the depth and extent of the magmatic chamber, which influence heat transfer by conduction. Additionally, uncertainties in the hydraulic properties of faults and lithofacies, which control fluid infiltration and consequently heat transfer by convection and advection, were considered. The results were calibrated against measured temperatures in wells.
These findings highlight the main controlling factors of the geothermal system in the Asal Rift, provide a 3D visualization of heat transfer and fluid circulation, and will enable future quantification of the geothermal potential of the area.
How to cite: Abdi Ali, A., Bonté, D., Souque, C., Traby, A., and Nader, F.: 3D Numerical Modeling of the High-Temperature Geothermal System in Asal-Ghoubbet Rift, Djibouti, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3115, https://doi.org/10.5194/egusphere-egu25-3115, 2025.
The island of Pantelleria, located in the Sicily Channel, is a volcanic system characterized by peralkaline (pantelleritic) magmatism and recurrent explosive eruptions, which have produced prominent caldera structures. Active geothermal manifestations, including gas emissions, hot springs, and elevated temperatures detected in deep boreholes, underscore its potential as a geothermal resource.
To elucidate the island's subsurface and enhance the understanding of its volcanic structures, geothermal reservoirs, and the pathways of hydrothermal fluid circulation, a magnetotelluric (MT) survey was performed, including 78 independent measurements. The resulting three-dimensional resistivity model delineates the geological and geothermal framework down to a depth of 2.5 km below sea level.
The resistivity anomalies imaged by the 3D electrical model can be associated with specific geological processes and physical conditions within the geothermal system, accurately identifying the main volcano-tectonic structures, particularly the rims of the La Vecchia and Cinque Denti calderas which drive the hydrothermal system's fluid circulation and storage.
This study highlights the fundamental role of caldera structures in influencing hydrothermal processes and improves our understanding of Pantelleria's geothermal potential. The results provide valuable insights for targeted exploration and sustainable exploitation of the island's geothermal resources.
How to cite: Isaia, R., Sposato, M., Di Giuseppe, M. G., Troiano, A., De Paola, C., and Di Maio, R.: Three-Dimensional Resistivity Imaging of Pantelleria Island: Insights into its Geothermal Potential, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20152, https://doi.org/10.5194/egusphere-egu25-20152, 2025.
Meteoric water infiltrates deeply into high-relief mountain ranges, heats up along its circulation path due to the background geothermal gradient and eventually discharges at lower elevation as thermal springs. Enabling such topographically-driven circulation depends on parameters such as permeability, hydraulic head, and thermal buoyancy of the rising water. Brittle deformation zones, especially active fault zones, often provide high-permeability fluid pathways due to repeated slip and refracturing. A systematic 4D analysis of such fault systems can therefore aid in identifying prospective sites in orogenic belts for more detailed geothermal exploration by 3D seismics and drilling.
Our ongoing GeoTex project investigates the geothermal potential of the Rhône Valley, SW Switzerland – a geothermally active Alpine zone with thermal springs, regional faults, and enhanced seismicity. Using structural field observations, seismological data, and remote sensing, we characterise fault geometries, kinematics and fault rocks in the vicinity of known thermal springs. Observable paleo-fluid pathways marked by hydrothermal veins and rock alteration are treated as analogues for recent thermal water circulation and are linked to major Alpine structures in the underlying basement units, such as large-scale strike-slip faults or the axial planes of uplifting basement domes. We identify three geodynamic domains with distinct fault characteristics: (1) A domain on the NW flank of the valley floor characterized by a NW–SE oriented maximum principal stress, high seismicity, and a pervasive network of strike-slip dominated faults; (2) a zone encompassing the valley floor with dilatant zones along strike-slip fault segments; and (3) a zone on the southern flank of the valley floor subjected to recent NE–SW extension expressed by dominantly normal to transtensional faulting focal mechanisms.
For each domain, we developed conceptual structural models helping to identify present-day fluid pathways. Integrating hydrochemical data (indicative of deep-geothermal fluid circulation) into our models, allows us to refine our understanding of such fluid pathways and to predict potential locations of blind active geothermal systems throughout the Rhône Valley and other Alpine settings.
How to cite: Herwegh, M., Schmid, T., Berger, A., Diehl, T., Madritsch, H., Diamon, L., Wanner, C., and van den Heuvel, D.: Detecting blind geothermal systems in orogenic belts: Structural controls on paleo-hydrothermal fluid pathways in the Rhône Valley, SW Switzerland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10192, https://doi.org/10.5194/egusphere-egu25-10192, 2025.
The Ruilin-Hongye region in Hualien County, Taiwan, represents a promising site for the development of non-volcanic geothermal energy resources. This study adopts an integrated approach, combining geological, geophysical, and geochemical analyses to assess geothermal potential and delineate reservoir characteristics. The region is located within the Yuli Belt, a complex metamorphic zone dominated by quartz-mica schists with interspersed mafic rock bodies. Geophysical surveys, particularly magnetotelluric (MT) surveys, have identified four shallow geothermal reservoirs at depths ranging from several hundred meters to approximately 1.5 kilometers. These reservoirs are distinguished by fractured and permeable rock formations, facilitating efficient hydrothermal fluid storage and circulation, which are crucial for geothermal energy development.
Geochemical analyses indicate a favorable thermal gradient across the region, supported by recharge from meteoric waters and groundwater inflow along local fault and fracture networks. Borehole temperature profiles combined with simulation data suggest that the reservoirs could support a generation capacity of approximately 14 MWe, positioning the area as a viable candidate for geothermal power production. The study also developed a conceptual 3D geological model, offering a detailed subsurface map that highlights high-potential zones and enables more targeted exploration and drilling strategies.
Our findings contribute to Taiwan’s renewable energy goals by demonstrating the feasibility of non-volcanic geothermal systems as a clean and sustainable energy source. This research underscores the importance of integrating geophysical and geochemical data to accurately characterize subsurface conditions, reduce exploration uncertainties, and optimize resource extraction. Future work should prioritize additional drilling and comprehensive monitoring to confirm production capacity and refine the development model, potentially advancing the role of non-volcanic geothermal systems in Taiwan's energy portfolio. By using such integrated methodologies, this study aims to mitigate development risks and enhance the efficiency of geothermal energy projects.
Keywords: Hualien, non-volcanic geothermal, Reservoir characteristics, Resource evaluation
How to cite: Wang, Y.-J., Yang, C.-H., Tan, C.-H., Yu, C.-W., Su, Z.-Z., Chen, C.-H., and Lin, H.-H.: Integrating Geophysical and Geochemical Insights for Geothermal Resource Evaluation in Taiwan's Ruilin-Hongye Region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3908, https://doi.org/10.5194/egusphere-egu25-3908, 2025.
Geothermal energy is increasingly considered as an energy alternative across off-grid indigenous communities in northern Canada. These communities primarily rely on diesel for electricity and a combination of oil, propane, wood, and diesel for heating. Burwash Landing, the seat of the Kluane First Nation government in Yukon Territory, Canada, is located on the shore of Łù'àn Män (Kluane Lake) at the base of the St. Elias Mountains and near a step-over in the Denali fault. A Play fairway analysis of southwestern Yukon highlights the geothermal favourability around Burwash Landing.
Over the past 15 years, Kluane First Nation has taken significant steps to reduce greenhouse gas emissions and drilled a community-led geothermal exploration borehole in 2012 (KFN‑L; 387 m). KFN‑L was drilled northeast of the Denali fault in Quaternary sediments. In 2021, the Yukon Geological Survey drilled a second exploration borehole (DRGW; 220 m) in bedrock to the southwest. This provided a unique opportunity to contrast geothermal context on either side of the Denali fault. The temperature gradients in KFN-L and DRGW are 45 and 35 ⁰C km-1, respectively. Fibre-optic digital temperature sensing was used to produce high-resolution thermal conductivity profiles for each borehole. These results led to a heat flux estimation of ⁓ 90 mW m-2 at both sites. The field results were then combined into a coupled groundwater flow and heat transfer model to evaluate temperature at depth.
This poster presents the evaluation of the geothermal potential around Burwash Landing, considering the influence of the Denali fault on local geothermal resources alongside socio-economic factors. Both the local geology and socio-economic factors are combined to offer Kluane First Nation context-informed recommendations for the integration of geothermal energy into their energy budget.
How to cite: Chapman, F., Soucy La Roche, R., and Raymond, J.: A holistic approach towards the integration of geothermal energy in remote northern communities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11858, https://doi.org/10.5194/egusphere-egu25-11858, 2025.
Time-lapse absolute and relative gravity surveys, are directly sensitive to the mass redistribution in the subsurface. These well-established methods allow for the monitoring of geothermal fields and for assessing the sustainability of the anthropogenic activities (water injection and extraction).
We apply the hybrid gravimetry method, in order to characterize the fluid redistribution within the subsurface. The hybrid gravimetry method combines absolute and relative microgravity time-lapse measurements and continuously recorded gravity time series. At Theistareykir geothermal field (Northern Iceland), we collected yearly time-lapse data at 26 fixed locations, and we recorded continuous data with 2 superconducting gravimeters (SGs), deployed within the hydrothermal field. Data acquisition started just before the beginning of operation of the powerplant in 2017, allowing us to monitor the hydrothermal system behaviour before and during anthropogenic perturbation.
After 7 years of data collection, we present here the gravity datasets (discrete and continuous) from 2017 to 2024. In particular, we show the continuous SGs signals and we detail the modelled gravity contributions (e.g., local tidal model, atmospheric loading, instrumental drift, ground deformation contribution). These modelled contributions are subtracted from the raw signal, to obtain gravity residuals. These residuals are then compared to the results from the microgravity and absolute surveys. Our datasets evidence a gravity decrease towards the extraction area of the geothermal field, and gravity increase towards the injection area. Furthermore, maps of 2017-2024 microgravity residuals, namely after correction of vertical ground deformation, display localized areas of gravity decrease (-60 µGal), that can be associated to low permeability zones in the production area, as well as small gravity increase (about +15 µGal) towards north (around the centre of injection). The gravity increase trend appears to be controlled by a well-known fissure swarm that crosses the area of Theistareykir.
In order to identify and quantify the hydrothermal processes from the observed gravity variations, we develop numerical functionalities for multi-phase fluid flow models using CSMP++ (Weis et al., 2014) to predict the gravity responses of simplified hydrothermal systems.
References
Weis, P., Driesner, T., Coumou, D., Geiger, S. (2014): Hydrothermal, multiphase convection of H2O-NaCl fluids from ambient to magmatic temperatures: a new numerical scheme and benchmarks for code comparison. - Geofluids, 14, 3, 347-371.
https://doi.org/10.1111/gfl.12080
How to cite: Giuliante, B., Jousset, P., Riccardi, U., Pivetta, T., Hinderer, J., Weis, P., Krawczyk, C., and Mortensen, A.: Subsurface masses monitoring at Theistareykir geothermal field, Iceland, using hybrid gravimetry., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15606, https://doi.org/10.5194/egusphere-egu25-15606, 2025.
Supercritical geothermal systems offer significant potential for enhanced energy production to support the energy transition due to their high enthalpies and the unique properties of supercritical fluids. However, development and utilisation of such promising resources are still in their infancy and face scientific uncertainties, financial and environmental risks, and engineering challenges. Supercritical hydrothermal reservoirs are inherently associated with proximity to magmatic plumbing systems below them. However, it is not yet well understood the extent to which degassed magmatic volatiles may contribute to supercritical hydrothermal reservoir fluid compositions.
CO₂ (and its species) constitutes the largest proportion of gas content from degassing magmas and hydrothermal fluids. Basaltic host rocks are closely associated with many high-temperature mafic magmatic systems around the world and are prime candidates to host supercritical geothermal reservoirs due to their highly reactive mineral compositions and vesicularity. Previous carbon capture and storage (CCS) focused fluid-rock interaction experiments have shown that basalt facilitates carbonation reactions, forming stable carbonate minerals and enabling the sequestration of atmospheric carbon. Here, we extend the scope of experimental investigations of CO2 brine interaction with basalt to simulate and quantify the effects of magmatic CO2 infiltration into a supercritical hydrothermal reservoir.
Two supercritical flow-through experiments were performed at 400°C and 500 bar using a high P-T titanium alloy autoclave system at the experimental hydrothermal geochemistry laboratory in GNS Science, New Zealand. In both experiments the same crushed basalt with a fraction size of 355-500 µm was used. In Experiment 1, distilled water and CO2 brine was injected for 42 days, while in Experiment 2, distilled water, CO2 and NaCl brine was injected for 49 days. Daily reacted effluent samples were analysed for major cations, anions, and trace elements by ICP-OES, IC and ICP-MS. Results show the development of alteration fronts across the host rock sample along the reactor’s depth in both Experiments 1 and 2. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) on the solid products from Experiment 1 reveal extensive dissolution of primary bytownite and secondary precipitation of chlorite, blocky calcite, and sphene covering the grain surfaces at the fluid entry point. Calcite precipitation was restricted to the fluid entry location whereas chlorite precipitation was observed along the entire reacted sample, decreasing in amount with distance from the fluid entry location. The penetrative dissolution of glass and primary bytownite deep into the basaltic grain alongside precipitation of secondary mineralogy suggests intact basaltic reservoir may experience fluid pathway evolution as CO2 brines move through them under supercritical conditions.
How to cite: Rybak, D. T., Sajkowski, L., Kilgour, G., Mountain, B., Kamiya, A., McNamara, D. D., and Kavanagh, J. L.: Experimental investigation of Basalt-CO2 brine interactions at supercritical conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12162, https://doi.org/10.5194/egusphere-egu25-12162, 2025.
The Juisui Geothermal Field, located in eastern Taiwan, is renowned for its hot springs, which are spread along the foothills and riverbanks. Covering only about 12 km², the area features a diverse range of springs, each with distinct characteristics, reflecting its location along a subduction mélange.
Around 15 to 10 Ma, turbidites at the edge of the Eurasian continent were affected by the rifting of the South China Sea. As a result, these rocks were subducted eastward, descending to depths of 40 to 60 km beneath the Philippine Sea Plate. The mantle wedge and oceanic plate’s basic/ultrabasic rocks mixed with sediments and experienced temperatures of up to 550 ℃ and pressures of 17 kBar (Tsai et al., 2013; Baziotis et al., 2017). These rocks were then rapidly uplifted to the surface due to orogeny. As a result, the host rocks in this area are not only quartz-mica schist, but also include serpentinite, meta-gabbro, epidote amphibolite, and Glaucophane schist. Shallow drilling can reach extremely high temperatures— for instance, the JS-5G well reaches 180℃ at just 190 m deep, and the highest temperature recorded was 204 ℃ at 1,428m in the CPC-JS-2 well.
This study analyzed 40 meteoric fluid samples to map the regional meteoric water line, and collected 77 spring and geothermal well samples during different seasons. The salinity of the hot spring water in the Juisui area ranges from 0.44 psu to 9 psu, while total dissolved solids (TDS) range from less than 520 mg/L to 6,550 mg/L. Bicarbonate concentrations range from 400 mg/L to 6,500 mg/L. Hydrogen isotope analysis suggests that the recharge for the springs may come from mountains at elevations of 830 to 1,100 m. These meteoric waters undergo different types of circulation: shallow circulation is heated by the geothermal gradient, which leads to lower concentrations and places the water on the meteoric water line. Deep circulation hot spring, characterized by Na-K ratios, falls between the greywacke line and the 1:1 line, indicating the mixing of deep brine or metamorphic water, and is far removed from the seawater 27:1. A few hot spring samples have especially high bicarbonate concentrations, indicating past flow through marble. Even when sampling from the same well (GSMMA-RS-1) at different times, there’s significant variation in salinity (ranging from 0.58 psu to 6.89 psu), which highlights the strong heterogeneity of the fluid properties— a key feature of the subduction Mélange. A positive oxygen isotopic shift suggests that deep circulation fluids have undergone water-rock interactions with various surrounding rocks in high-temperature environments.
In terms of mineral saturation, the Saturation Index for both calcite and aragonite in the region is either saturated or near saturation. This suggests that scaling could be an issue in future development, and strategies to prevent it should be considered.
How to cite: Lu, Y.-C., Song, S.-R., Peng, T.-R., Song, T.-J., and Lee, J.-C.: Chemical Characteristics of Geothermal Fluids in the Subduction Mélange: Insights from the Juisui Geothermal Field, Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16574, https://doi.org/10.5194/egusphere-egu25-16574, 2025.
Chemical clogging is one of the main issues arising in geothermal systems hindering the efficient operation, especially the thermal water reinjection. Hydrogeochemical models are able to assess the risk of mineral precipitation and provide quantitative estimation of the degradation of hydraulic properties.
A Python based simplified Graphical User Interface (named PHREI) was created with the abilities of a previously developed and published geochemical model setup. The Python source code of the GUI package can be found via the https://github.com/marabukok/PHREI page. This setup aims to reproduce the main geochemical processes of a geothermal loop from production until reinjection into the aquifer. The forming scale cumulated over time is then used to estimate the porosity and permeability degradation in the near-wellbore zone.
PHREI is applicable without creating new hydrogeochemical model setups by entering the parameters in pop-up windows: fluid composition of production well and reservoir fluid, mineral composition of the reservoir, flow rate, initial porosity and dimensions of gravel pack or the near well-bore zone, reinjection and reservoir temperature. Outcome of the model provides first estimate of clogging risk in doublet systems, as an example a theoretical period of time in which porosity is decreased by half. PHREI was tested at a geothermal doublet system suffering from low injectivity and used for pre-screening of thermal wells and regions with respect to the clogging risk. This way results contribute to a mapping of clogging related risk in the geothermal reconnaissance phase. Hence it can be part of the analysis of reinjection related risk, and the “geothermal reinjection potential”.
The first author was supported, and the research was financed through the KDP-2021 Cooperative Doctoral Programme of the Ministry of Culture and Innovation of 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. and Pedretti, D.: PHREI – A simplified Python based Graphical User Interface for PHREEQC to model to chemical clogging processes in reinjection wells , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3613, https://doi.org/10.5194/egusphere-egu25-3613, 2025.
Geochemical methods are extensively used in geothermal exploration and exploitation phases, played a major role in both the identification and utilization of resources. In regions where geothermal systems are concealed or located at significant depths, soil gas surveys become indispensable. These methods focus on detecting anomalous concentrations of hydrothermal gases within the soil atmosphere, providing key insights into subsurface geothermal activity. Previous studies in the western area of La Palma island (Canary Islands, Spain) identified the highest geothermal potential of the studied areas. Consequently, more detailed investigations were conducted in the zones with the most significant anomalies to better characterize their potential for economic exploitation. A detailed geochemical survey with an average measurement spacing of ~12 m was carried out in an area of 0.11 Km2 at Puerto Naos. A total of 561 sites were sampled at 40 cm depth using a metallic probe. Gas samples were collected with 60 cc hypodermic syringes and stored in 10 cc glass vials for subsequent laboratory analyses. Spatial distribution maps of diffuse He, H2, CH4 and CO2 emission and δ13C-CO2 were constructed to study the presence of enhanced vertical permeability areas related to high temperature hydrothermal activity at depth. The main CO2, H2 and δ13C-CO2 anomalies reveal two well-defined zones located in the southeast and west of the study area. In contrast, He highest values are observed in the northern and southern regions. These patterns may be attributed to secondary processes, including interactions with coastal water and the varying reactivity and mobility of the analyzed species. The spatial distribution of soil gases in Puerto Naos confirms a relative enrichment of and H₂, He, CH4 and CO₂ in the soil gas atmosphere, suggesting a significant contribution from deep-seated sources. These studies aid in identifying permeable zones and potential upflow areas associated with geothermal system structures, thereby facilitating a more efficient subsequent phase of subsurface exploration.
How to cite: Melián, G. V., Hei Ho, C., Henry, L., Plaza, K., Pérez, N. M., Taño Ramos, D., Trujillo Vargas, L., Ramos Delgado, C., Cartaya, S., Arencibia, M., Gironés, A., Asensio-Ramos, M., Padrón, E., Hernández, P. A., and Padilla, G. D.: Soil gas CO2, He, H2 and isotopic ratios for surface geothermal exploration in Puerto Naos, La Palma, Canary Islands. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13599, https://doi.org/10.5194/egusphere-egu25-13599, 2025.
Geothermal systems become viable when conditions, like appropriate temperature ranges, geological structures, and petrophysical properties, exist less than 3-5 km near surfaces. Assessing these factors is crucial for identifying economically viable geothermal resources. A key aspect of this evaluation is understanding subsurface electrical resistivity, which plays a pivotal role in characterizing geothermal systems. This study focuses on investigating geothermal resources and sites for geothermal power plants in the Tatun Volcano Group (TVG) in Northern Taiwan. Magnetotelluric (MT) methods, in particular, have emerged as a fundamental and powerful tool in geothermal exploration and subsurface architecture beneath geothermal areas. By performing 3D resistivity inversion of MT data collected from 47 measurement stations, this research develops a comprehensive model of subsurface electrical resistivity. Cross-sections and maps at various elevations are generated from this model to identify resistivity patterns essential for geothermal sites and to construct geological cross-sections for advancing geothermal exploration, such as further drilling.
The study highlights three potential geothermal areas with a high-resistivity core beneath a low-resistivity clay cap. Moreover, this study establishes several cross-sections across the north tip of Taiwan. A comparison between magnetization-derived airborne magnetic surveys, gravity-derived density models, and current 3D resistivity models leads to completing these cross-sections. They manifest subsurface architecture and elucidate the structural development. These results offer important new information for developing geothermal research in the TVG area.
How to cite: Nguyen, T. L. C., Huang, W.-J., Chen, C.-C., Yen, C.-S., Chen, C.-H., and Tong, L.-T.: Application of Magnetotelluric (MT) Methods in Geothermal Exploration and Geostructural Investigation: A Case in Tatun Volcano Group, Northern Taiwan , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10278, https://doi.org/10.5194/egusphere-egu25-10278, 2025.
Geothermal resources represent a significant opportunity for clean baseload energy in Europe, yet their development remains largely untapped. A key barrier to expanding geothermal energy is the challenge of greenfield exploration, where traditional active seismic methods face high costs, complex logistics, and limited depth resolution, which elevate project risks. Recently, ambient noise tomography, a passive seismic imaging technique, has emerged as a promising alternative due to its affordability, scalability, and ease of deployment.
As part of the EU-funded GeoHEAT project, we aim to integrate passive geophysical imaging methods at both regional and reservoir scales into a comprehensive, cost-effective exploration workflow. This will ultimately produce a ranked list of the most promising drilling locations within a given region. The canton of Thurgau in Switzerland has been selected as a test site due to its interesting geological setting, strong local political support, and availability of existing geological and geophysical data. In March 2025, a network of roughly 300, 3-component nodal seismic sensors will be deployed to survey an area approximately 30 by 50 km2. The primary geological targets of this survey include the topography of the crystalline basement and the identification of potential sedimentary troughs and deep fractured zones.
This presentation will outline our proposed passive seismic exploration workflow, emphasizing its simplicity and applicability. We will also present early results from the newly acquired dataset, including group velocity maps. By demonstrating the alignment of passive seismic 3D models with existing subsurface data and incorporating these models into a probabilistic framework that quantifies subsurface uncertainties, we aim to accelerate the adoption of scalable, low-cost exploration techniques. This work is funded by the Swiss State Secretariat for Education, Research, and Innovation (SERI) and the European Union through the GeoHEAT project under Horizon 2020. GeoHEAT seeks to transform geothermal exploration by creating an innovative, low-cost, multi-scale workflow, spanning from regional to borehole levels. The project emphasizes a transparent and quantitative approach to effectively communicate risks to all stakeholders.
How to cite: Savard, G., Munoz-Burbano, F., Cusin, H. T., Lupi, M., Finger, C., Löer, K., Villiger, L., and Shakas, A.: Geothermal exploration with passive geophysical methods in the canton of Thurgau, Switzerland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21379, https://doi.org/10.5194/egusphere-egu25-21379, 2025.
Geothermal energy is a sustainable and environmentally friendly solution for power generation and district heating/cooling, offering continuous availability throughout the day and year. Despite its global potential, targeted strategies are essential for advancing geothermal resource exploitation.
The InGEO project ("Innovation in GEOthermal resources and reserves potential assessment for the decarbonisation of power/thermal sectors"; www.ingeo.cnr.it) seeks to develop an innovative exploration workflow integrating geological, geophysical, thermophysical, and other datasets to enhance the characterization of potential geothermal reservoirs. This approach can support strategic planning, with scientific information voted to exploit deep geothermal resources in Italy.
Deep-seated carbonate reservoirs, forming the basement of sedimentary basins, are key targets for geothermal development in Italy, they are the main focus of the analyzed case study. In the eastern Po Plain, the buried Romagna and Ferrara Folds (RFF)—stretching from the Emilia Folds to the Adriatic coast and from the northern Apennines to the undeformed Po foreland—show significant geothermal gradient variations, indicative, in some cases of low gradient, of possible convective heat flow in deep carbonate units. Pasquale et al. (2013) reported low geothermal gradients (14 °C/km) within the carbonate reservoir and higher gradients (53 °C/km) in overlying impermeable formations, confirming thermal convection within Mesozoic carbonate units.
To investigate this area, we digitised and analysed a large amount of data, considering over 200 seismic surveys (VIDEPI database, www.videpi.com), 700 deep boreholes (>1500 m deep; CNR database, www.geothopica.igg.cnr.it), and 160 borehole logs (sonic and lithological; Livani et al., 2023), covering ~22,500 km². This extensive dataset underpins the development of a detailed 3D geological model that delineates the thickness variations of major lithological units to a depth of ~10 km. Seismic reflection interpretations, constrained by available well stratigraphy, were used to identify key lithological unconformities.
The resulting 3D geological model represents a fundamental tool for assessing the basin's geothermal potential and refining exploration workflows applicable to analogous basins. The final obtained geothermal model will serve as a benchmark for evaluating geothermal resources and as input for testing the consistency of various geophysical datasets (Basant et al., 2025) and an open-source, web-based GIS tool for multiple applications.
The InGEO project is part of the PRIN 2022 PNRR initiative and is funded by the European Union’s Next Generation EU program.
References
Basant R., Cortassa V., Tesauro M., Gola G., Nanni T., Galgaro A., and Manzella A. Joint interpretation of geophysical data for evaluating the geothermal energy potential in the Romagna and Ferrara Folds (Italy). Gruppo Nazionale per la Geofisica della Terra Solida (43° National Conference GNGTS), Bologna, 11-14 February 2025 (Abstract).
Pasquale, V. Chiozzi, P., and Verdoya, M., 2013. Evidence for thermal convection in the deep carbonate aquifer of the eastern sector of the Po Plain, Italy. Tectonophysics 594, 1-12. 15.
Livani, M., Petracchini, L., Benetatos, C., Marzano, F., Billi, A., Carminati, E., et al.,2023. Subsurface geological and geophysical data from the Po Plain and the northern Adriatic Sea (north Italy). Earth System Science Data Discussions, 2023, 1-41.
How to cite: Cortassa, V., Tesauro, M., Basant, R., Gola, G., Nanni, T., Galgaro, A., and Manzella, A.: A 3D Geological Model of the Romagna and Ferrara Folds, (Eastern Po Plain) for advanced deep geothermal exploration, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12131, https://doi.org/10.5194/egusphere-egu25-12131, 2025.
The Mediterranean–Himalaya tectonic belt across the Eurasian continent is one of the most famous geothermal abnormal zones in the world. Advances in the exploration of the geothermal resources with remarkably high temperatures in the Gonghe Basin, northeastern Tibetan Plateau, provide an enhanced understanding of the origin and emplacement of hot dry rock (HDR). Based on the integrating analysis on the boundary faults distribution and their activity histories, springs, and geothermal borehole data, and magnetotelluric data, we propose that the Gonghe Basin formed in a zone of slip dissipation between two major large-scale left-lateral strike-slip faults of the Kunlun fault to the south and the Haiyuan fault to the north during the Neogene evolution. During the evolution of these two major strike-slip faults, the basin has experienced two-phase developments: the transrotational Gonghe-Qinghai lacustrine basin system during the Miocene, and the transpressional Gonghe-Tongde basin system during the Pliocene-Quaternary. In response to the crustal transtension components of the transroational Gonghe Basin, the partial melting zone at depths of 10–25 km in the thickened crust (~54 km) has been uplifted by ~10 km compared with adjacent regions since the Pliocene. This uplifted partial melting zone may have provided prominent potential heat energy for the HDR in the Triassic granitoid batholith at shallower depths (~3–10 km) by effective enhancement of the geothermal conduction process via deep faulting. With obliquely south-verging thrusting of the Gonghe Nan Shan thrusts in the northern, the Gonghe Basin has transformed from transrotation to transpression-domination during the 6–3 Ma, as well as accompanying with the depocentre migrating to the northwest and in turn the basement elastically uplifting in the southeast. This differential deformation of the basin floor has resulted in a northeastward upward tilting of the Triassic batholith and an isothermal surface. It finally developed he high-temperature and shallow-burial HDR with anomalously temperatures of over 100 °C at a depth of 1.5 km in the Qiabuqia and Zhacang geothermal areas in the Gonghe Basin, NE margin of the Tibetan Plateau.
How to cite: Tang, X., Zhang, D., and Li, C.: The Cenozoic transformation and tectonic evolution: implication for the genesis and heat accumulation of Gonghe basin, Northeastern Tibetan Plateau, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15023, https://doi.org/10.5194/egusphere-egu25-15023, 2025.
Posters virtual: Thu, 1 May, 14:00–15:45 | vPoster spot 4
EGU25-3869 | Posters virtual | VPS17
Tatun Volcanic Group geothermal assessment: estimated radiative heat flux and heat loss from satellite thermal time-series datasetsThu, 01 May, 14:00–15:45 (CEST) | vP4.7
Taiwan's Tatun Volcanic Group (TVG) is an active tectonic zone that moved from tectonic compression zones to crustal expansion. It is a graben, or region of crustal thinning structure, that is favorable to crustal magmatic intrusion. This geologic context supplies heat for the formation of geothermal and volcanic systems. In addition, TVG is a suitable location for geothermal exploration because of the numerous surface thermal characteristics associated with young volcanic rocks. By computing the geothermal radiative heat loss based on the land surface temperature (LST) obtained from thermal sensors on Earth-observing satellites, we can assess the geothermal resource reservoir of TVG. Firstly, the Stefan-Boltzmann law from the LSTs is used to derive the radiative heat flow (RHF). Second, the sum of the heat flux pixel values over the selected geothermal area is used to estimate the overall radiative heat loss (RHL). The background radiative heat loss is then computed, and by deducting the background radiative heat loss from the total radiative heat loss, geothermal (i.e., net) radiative heat loss is determined. The above process determines trends in geothermal radiative heat loss over time. The average value of the four-decade (1984 - 2024) trend of geothermal radiative heat loss at TVG is 211 MW, with an annual rate of increase of 1 MW (MegaWatt) each year. The mean value of heat loss estimation follows the same sequence as the traditional geochemical method used in earlier research. On the other hand, this study's annual growing rate estimation of TVG is noted for the first time. This study shows the advantages and benefits of employing long-term remote sensing datasets in geothermal and volcanic investigations. It is the first attempt to assess TVG's geothermal potential using satellite thermal observations. This application of remote sensing methods in TVG's geothermal investigation shows encouraging outcomes and can be applied to other geothermal systems across the globe.
How to cite: Chan, H.-P. and Chan, Y.-C.: Tatun Volcanic Group geothermal assessment: estimated radiative heat flux and heat loss from satellite thermal time-series datasets, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3869, https://doi.org/10.5194/egusphere-egu25-3869, 2025.
EGU25-15478 | Posters virtual | VPS17
Detailed surface geothermal exploration by means of diffuse CO2 efflux, radon measurements and radon/thoron ratio in Jedey, La Palma, Canary IslandsThu, 01 May, 14:00–15:45 (CEST) | vP4.8
Soil diffuse CO2 efflux and soil radon (222Rn) and thoron (220Rn) gases activities measurements may be useful geochemical indicators of subsurface volcano-hydrothermal processes in geographical areas where visible gas emissions are nearly absent. Both radon (222Rn) and thoron (220Rn) are radioactive isotopes derived from the natural decay of uranium (238U) and thorium (232Th) respectively, present in the mineralogical composition of rocks. The main difference between these two isotopes is their half-life time. While 222Rn presents a half-life of 3.8 days, 220Rn has a shorter half-life of 55 seconds. Therefore, high 222Rn surface activity is considered to be associated with deep magmatic sources of gas while high 220Rn activity is associated with shallow soil gas sources.
A total of 968 sampling sites in an area of 25 Km2 have been considered as part of a detailed surface geochemical study at the central-western part of La Palma and southwards from the 2021 volcanic eruption lava flow of Tajogaite Volcano. Both diffuse soil CO2 efflux and radon and thoron activities discrete measurements were executed during field surveys between 2023 and 2024.
The diffuse CO2 efflux measurements were determined, based on the non-stationary static accumulation chamber technique, using CO2 sensors contained in a portable flux-meter, and the radon and thoron activities were evaluated using a SARAD radon monitor connected to a stainless steel probe inserted at 40 cm depth. Soil gas samples were also collected and analyzed in the laboratory to obtain the chemical and carbon isotopic composition profile.
Data analysis and treatment showed CO2 efflux values up to 106 g*m-2/day, 222Rn values up to 27000 Bq/m3 and 222Rn/220Rn ratio up to a maximum of 49. Both 222Rn versus 222Rn/220Rn ratio plotted together enabled to identify areas with a higher contribution of deeper sourced gas,which might indicate potential zones of interest of geothermal resources.
Furthermore, spatial distribution maps of these variables showed that the main CO2 and radon gases anomalies are located along the coastline of the studied area, coincident with anomalous magmatic-hydrothermal origin CO2 diffuse degassing areas. The magmatic-hydrothermal CO2 might have acted as a carrier gas controlling the migration and transport of the radon trace gas towards the surface.
In conclusion, surface geochemical surveys might be useful for geothermal resources exploration studies, providing a reasonable definition of potential geothermal system boundaries and permitting an efficient and cost-effective posterior subsurface exploration phase.
How to cite: Gironés, A., Pérez, N., Padrón, E., Melián, G. V., Asensio-Ramos, M., Hernández, P. A., Padilla, G. D., Di Nardo, D., Martín, A., Ramos, C., Taño, D., and Trujillo, L.: Detailed surface geothermal exploration by means of diffuse CO2 efflux, radon measurements and radon/thoron ratio in Jedey, La Palma, Canary Islands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15478, https://doi.org/10.5194/egusphere-egu25-15478, 2025.
