Geothermal Resources Research Articles

Probabilistic assessment of deep geothermal resources in the Cornubian Batholith and their development in Cornwall and Devon, United Kingdom

Geothermal energy could play a pivotal role in decarbonisation as it can provide clean, constant base-load energy which is weather independent. With a growing demand for clean energy and improved energy security, geothermal resources must be quantified to reduce exploration risk. This study aims to quantify the untapped resource-potential of the Cornubian Batholith as a geothermal resource for power generation and direct heat use. Recent field work, laboratory measurements and petrophysical characterization provides a newly compiled dataset which is inclusive of subsurface samples taken from the production well of the United Downs Deep Geothermal Power Project. Deterministic and probabilistic calculations are undertaken to evaluate the: total heat in place, recoverable resource, technical potential and potential carbon savings. The Cornubian Batholith is considered a petrothermal system which may require stimulation as an enhanced geothermal system. This study shows the batholith has significant heat stored of 8988 EJ (P50), corresponding to 366 EJ recoverable and a technical potential of 556 GWth. When evaluating the potential for power generation (i.e., electricity) the P50 is 31 GWe. The total carbon savings when generating electricity (P50) equates to 106 Mt.

Discussion on Deep Geothermal Characteristics and Exploration Prospects in the Northern Jiangsu Basin

The Northern Jiangsu Basin (NJB), located at the northeast edge of the Yangtze block, is not only rich in oil and gas resources but also contains abundant geothermal resources. Nevertheless, the distribution of geothermal resources at medium depth in the NJB is still unclear due to its complex geological structure and tectonic–thermal evolution process, which restricts its exploitation and utilization. The characteristics of the geothermal field and distribution of geothermal reservoirs within the NJB are preliminarily analyzed based on available temperature measurements and geothermal exploration data. The prospective areas for the exploration of deep geothermal resources are discussed. The analysis results show that (1) Mesozoic–Paleozoic marine carbonate rocks are appropriate for use as principal geothermal reservoirs for the deep geothermal exploration and development within the NJB; (2) the geothermal field is evidently affected by the base fluctuation, and the high-temperature area is mainly concentrated at the junction of the Jianhu uplift and Dongtai depression; (3) the southeast margin of Jinhu sag, Lianbei sag, the east and west slope zone of Gaoyou sag, the low subuplifts within the depression such as Lingtangqiao–Liubao–Zheduo subuplifts, Xiaohai–Yuhua subuplifts and the west of Wubao low subuplift, have good prospects for deep geothermal exploration.

Study on the integrity assessment of geothermal wellbore under thermal and non-uniform in-situ stresses coupling effects

During the development of geothermal resources, thermal and non-uniform in-situ stresses can lead to wellbore integrity failures in geothermal wells. To evaluate the integrity of casing-cement-formation combination system under coupled thermal and non-uniform in-situ stress, an integrity evaluation mathematical model is established based on thermodynamics, elastodynamics, and the equivalent stress criterion. The performance of cement sheath mechanics and combination system sealing under different temperature conditions is investigated based on the designed experimental apparatus. By integrating numerical simulation and experimental approaches, a method to evaluate the integrity of the wellbore combination system in geothermal wells has been developed and the risk of temperature variations and non-uniform in-situ stresses on the casing, cement sheath, Cementing I and II interfaces has been analysed. Experimental results show significantly reduced mechanical and sealing performance under high temperature conditions. Numerical simulations indicate that the Cementing I and II interfaces, as well as the cement sheath, serve as weak points for potential integrity failure in geothermal wells, but the potential failure risk of Cementing I interface is higher. The developed method can effectively evaluate the wellbore combination system integrity under the coupling effect of thermal stress and non-uniform in-situ stress, which is crucial for ensuring the wellbore integrity and safe development of geothermal energy.

High-Resolution 3D Shallow S-Wave Velocity Structure Revealed by Ambient-Noise Double Beamforming with a Dense Array in Guangzhou Urban Area, China

Abstract Shallow velocity structure surveys are very important for urban seismic hazard monitoring and risk assessment. Ambient-noise tomography provides an ideal way to obtain urban fine structure. In this study, we obtained a high-resolution 3D VS model of the metropolitan areas of the Pearl River Delta (PRD) using the ambient-noise double-beamforming method with a dense nodal array. The new model reveals shallow structures that correlate well with surface geological features, with low-velocity anomalies in fault depressions and high-velocity anomalies in fault uplifts. Our findings reveal detailed fault geometries and basin characteristics of the PRD. The Guangzhou–Conghua fault emerges as a prominent velocity boundary, playing a significant role in controlling the development and subsidence of the Longgui basin. The Xinhui–Shiqiao fault and Shougouling fault are identified as major faults that control the formation and evolution of depressions in the PRD. The basin structures in the PRD are classified as semigraben basins controlled by synsedimentary faults. The long axes of the sub-basins align with the strike of the major faults, and the deposit centers are located in close proximity to these faults. Furthermore, our investigation reveals low-velocity anomalies along the faults, suggesting the existence of pre-existing faults facilitating heat transfer and fluid/melt migration from the deep crust. Our results provide new constraints on the geometric structure of the sedimentary basins and fault systems in the PRD area, thereby contributing to urban seismic hazard assessment and offering valuable insights into potential geothermal resources.

Growth mechanism of high‐voltage electric pulse rock breaking 3D plasma channel in drilling fluid environment

AbstractHigh‐voltage electric pulse rock breaking has excellent potential for exploiting deep geothermal resources. Numerous researchers have conducted experimental studies on this topic, particularly in rock mechanics, where the breakdown occurs. However, there has been limited scholarly research on drilling fluid. Therefore, the study focuses on the drilling fluid suitable for electric pulse drilling, considering the characteristics of electric pulse rock breaking, which differ from traditional rock breaking. The study focused on the impact of various drilling fluid parameters on the effectiveness of electric impulse rock breaking using red sandstone as the experimental material. This was investigated using the finite element method, and indoor electric rock‐breaking tests were conducted in a drilling fluid environment. The results indicate that the plasma channel mainly grows in the permeable layer of the drilling fluid, resulting in shallow rock breaking depth in the drilling fluid environment. The pore permeated by drilling fluid guides the growth of the plasma channel. The higher the conductivity of the drilling fluid, the closer the ion channel of rock breaking by electric pulse is to the rock surface. This results in a smaller crushing volume and shallower damage depth, which is more detrimental to rock breaking by an electric pulse. The viscosity of drilling fluid can impede the breakdown to some extent. In this paper, the influence of drilling fluid parameters on electro‐pulse rock‐breaking technology is preliminarily studied, which has significant reference value for the selection of actual drilling fluid.

Prediction of geothermal temperature field by multi-attribute neural network

Hot dry rock (HDR) resources are gaining increasing attention as a significant renewable resource due to their low carbon footprint and stable nature. When assessing the potential of a conventional geothermal resource, a temperature field distribution is a crucial factor. However, the available geostatistical and numerical simulations methods are often influenced by data coverage and human factors. In this study, the Convolution Block Attention Module (CBAM) and Bottleneck Architecture were integrated into UNet (CBAM-B-UNet) for simulating the geothermal temperature field. The proposed CBAM-B-UNet takes in a geological model containing parameters such as density, thermal conductivity, and specific heat capacity as input, and it simulates the temperature field by dynamically blending these multiple parameters through the neural network. The bottleneck architectures and CBAM can reduce the computational cost while ensuring accuracy in the simulation. The CBAM-B-UNet was trained using thousands of geological models with various real structures and their corresponding temperature fields. The method’s applicability was verified by employing a complex geological model of hot dry rock. In the final analysis, the simulated temperature field results are compared with the theoretical steady-state crustal ground temperature model of Gonghe Basin. The results indicated a small error between them, further validating the method's superiority. During the temperature field simulation, the thermal evolution law of a symmetrical cooling front formed by low thermal conductivity and high specific heat capacity in the center of the fault zone and on both sides of granite was revealed. The temperature gradually decreases from the center towards the edges.

Optimizing Micro-CT Resolution for Geothermal Reservoir Characterization in the Pannonian Basin

In the context of global efforts to transition toward renewable energy and reduce greenhouse gas emissions, geothermal energy is increasingly recognized as a viable and sustainable option. This paper presents a comprehensive assessment derived from a subset of a larger sample collection within the Dunántúli Group of the Pannonian Basin, Hungary, focusing on optimizing micro-computed tomography (µ-CT) resolution for analyzing pore structures in sandstone formations. By categorizing samples based on geological properties and selecting representatives from each group, the study integrates helium porosity and gas permeability measurements with µ-CT imaging at various resolutions (5 µm, 2 µm, and 1 µm). The findings reveal that µ-CT resolution significantly affects the discernibility and characterization of pore structures. Finer resolutions (2 µm and 1 µm) effectively uncovered interconnected pore networks in medium- to coarse-grained sandstones, suggesting favorable properties for geothermal applications. In contrast, fine-grained samples showed limitations in geothermal applicability at higher resolutions due to their compact nature and minimal pore connectivity, which could not be confidently imaged at 1 µm. Additionally, this study acknowledges the challenges in delineating the boundaries within the Dunántúli Group formations, which adds a layer of complexity to the characterization process. The research highlights the importance of aligning µ-CT findings with geological backgrounds and laboratory measurements for accurate pore structure interpretation in heterogeneous formations. By contributing vital petrophysical data for the Dunántúli Group and the Pannonian Basin, this study provides key insights for selecting appropriate µ-CT imaging resolutions to advance sustainable geothermal energy strategies in the region. The outcomes of this research form the basis for future studies aimed at developing experimental setups to investigate physical clogging and enhance geothermal exploitation methods, crucial for the sustainable development of geothermal resources in the Pannonian Basin.

Hydrogeological parameterisation of the Daruvar thermal aquifer: integration of fracture network analysis and well testing

Highly fractured Mesozoic carbonate rocks are the main reservoir of many geothermal resources in northern Croatia, being of environmental, cultural, and economic value for the local and regional communities. The Daruvar thermal springs (temperatures < 50°C) represent the outflow area of an intermediate scale, tectonically controlled, hydrothermal system hosted in Triassic carbonate rocks. Several investigations have been conducted in the Daruvar area detailing the architecture of regional and local fracture networks and quantifying the hydrogeological parameters of the thermal aquifer. In this work, an integrated approach based on structural and hydrogeological investigations was employed to model the network of fractures in the reservoir and quantify its impact on the hydraulic properties. Structural investigations were conducted in the Batinjska Rijeka quarry, considered as an outcrop analogue of the thermal aquifer, employing both a classical field approach and the virtual quantitative analysis of a 3D digital outcrop model. Structural analysis of the digital outcrop model allowed identification of two sub-vertical systems of discontinuities, dipping to the NW and the WSW respectively, in accordance with the data collected through direct field measurements. The main geometric features of the discontinuity network and their statistical distributions were employed to construct discrete fracture network models at both the outcrop scale (approximately 100 m) and the aquifer scale in Daruvar (approximately 700 m). Calibration of the input parameters allowed modelling of porosity and permeability values that reproduce the field values assessed through pumping tests, well tests, and well logging. This work highlights the importance of integrating geological and hydrogeological investigations to obtain a more reliable reconstruction and quantification of the processes driving the fluid flow in fractured aquifers and affecting the spatial distribution of their hydraulic properties.

Configuration method for medium-deep ground source heat pump system considering renewable energy consumption and smart grid interaction

Medium-deep ground source heat pump (GSHP) systems have the advantages of low carbon, high heat exchange intensity, good thermal storage capacity, and intermittent operation characteristics, which are conducive to renewable energy consumption and grid demand response. The source-side parameters affect the configuration of underground borehole engineering, heat pump units, and other equipment. However, current research mainly focuses on the underground heat exchanger modeling, underground heat exchange, and system operation control, while there are few studies on multi-factor ground source-side parameter design and optimal configuration. In this study, the indicator analyzing the unsteady features and thermal balance state of medium-deep geothermal resources was introduced, and the source-side water temperatures were optimized based on the dynamic characteristics of the geothermal and building sides. A simulation configuration methodology for the source-side flow rate and storage capacity was developed considering the electricity prices, life-cycle cost (LCC), and grid interaction. The optimization of the ground source-side design temperature, flow rate, and capacity parameters of residential and office building heating scenarios were analyzed in northern China, respectively. The results showed that the borehole inlet and outlet temperature can be designed to 5.5 °C/17.5 °C under the annual sustainable state, and the optimal flowrate can be set to 65.77 m3/h, to achieve the lowest cost and highest heating season guarantee rate for the residential scenario. For the office building with optimal system and storage capacity, the average annual LCC is 192,000 yuan/year, with the cumulative peak shaving of 55.8 %, and an increase of 103.3MWh renewable electricity consumption.

Numerical analysis of coupled thermal–hydraulic processes based on the embedded discrete fracture modeling method

The enhanced geothermal system (EGS) technology is considered an effective way to extract energy from deep hot dry rock (HDR) geothermal resources, which involves the coupling of complex thermal–hydraulic processes in fractured geological media. In this work, we propose a numerical approach based on the concept of embedded discrete fracture modeling method (EDFM), to estimate heat production performance from the EGS. We validated the method by comparing the outputs of our numerical models with experimental data and analytical solutions. A simplified, idealized two-dimensional model with discrete fractures was applied to gain insights on mass and heat transfer mechanisms expected under field conditions. Simulation results indicated that isolated and dead-end fractures have little influence on the overall performance of EGS, under the initial and boundary conditions of our numerical experiments (e.g., fracture density and permeability differences between fractures and matrix). It emerges that geometry and hydraulic transmissivity of fractures are key factors in controlling the effectiveness of the heat exchange between host rocks and circulating fluids. This work emphasizes the importance of implementing increasingly reliable descriptions of the fluid-dynamic and thermodynamic behavior of fractures, to increase the confidence in the numerical assessment of the performance of EGS installations.

Experimental study on dynamic deformation and breaking mechanism of high-temperature hard rock cutting by abrasive water jet

The development of deep geothermal resources encounters challenges related to high temperatures and hard reservoir rocks. Abrasive water jets (AWJ) offer a potential solution to enhance the efficiency of breaking high-temperature hard rocks in deep ground. This mainly originated from their combined characteristics of jet cooling impact and high-speed abrasive grinding. In order to investigate the dynamic deformation process and rock-breaking mechanism of high-temperature hard rocks cut by AWJ, laboratory tests were conducted on high-pressure abrasive water jets cutting granite, sandstone, and marble. Rock strains were monitored using dynamic strain gauges and the digital image correlation (DIC) technique. The results indicate that in the process of abrasive jet cutting high-temperature hard rock, the rock strain is divided into three stages: compression deformation, deformation release, and stable deformation. The strain response zone can be divided into strain concentration zone, strain transition zone, and strain weak response zone. The high strain region and heat exchange region of high-temperature hard rock during AWJ cutting process are almost consistent. Jet vaporization weakens the water cushion effect during the water hammer stage, leading to high strain concentration at the stagnation point of the jet. During the stagnation stage, the fluid weakens the binding of particles, the abrasive becomes more divergent, and the range of high strain response region expands. Unlike the dynamic strain generated by jet erosion of hard rock, when jet cutting rocks, the strain in the vertical jet direction is generally greater than that along the jet direction. The cutting effect increases with the increase of rock temperature. When the rock temperature is 300 °C, the cutting depth of sandstone, granite, and marble increases by 50 %, 120 %, and 180 %, respectively. Under the combined effects of high-frequency jet impact, high-speed abrasive grinding, and thermal stress, hard rock undergoes varying degrees of damage and failure.

De-risking green energy from mine waters by developing a robust hydrogeological conceptual model of the UK Geoenergy Observatory in Glasgow

Mine-water geothermal resources have potential to provide low-carbon heating and cooling in many areas; however, this potential has not been fully realised due to technical, economic and policy challenges. The UK Geoenergy Observatory (UKGEOS) in Glasgow was developed to provide an at-scale research facility designed to help de-risk mine-water geothermal usage. The limited knowledge of the hydrogeological systems altered by former mining activities is a key determinant of the long-term sustainability of water and heat abstraction/reinjection. This work presents a hydrogeological conceptual model developed using groundwater monitoring data obtained during the construction of the Observatory between 2020 and 2022, results from initial pumping tests performed in 2020, and results of hydrochemistry analysis from 25 sampling rounds collected between 2019 and 2022. The analysis of the data provides evidence of the dominant role of mine workings in controlling groundwater flow, with high intra-mine connectivity; increased fracturing in sandstones above mine workings; and limited inter-mine connectivity. Groundwater recharge is meteoric, mean residence times are >50 years, and there is a general upwards circulation from the deeper mine levels to the superficial deposits and the River Clyde. Faults play a significant role in limiting the extent of the highly transmissive mine workings, but there remains uncertainty surrounding the role of the faults in connecting different mine workings and their hydraulic behaviour in nonmined units. The conceptual model, that will be refined as new data become available, will be used to help guide monitoring and sampling programs and plan research activities in the Observatory.

Record of a pioneering geothermal borehole in London

This paper records the results of a pioneering exploration borehole drilled in 1984 to a depth of 403.84 m in the London Basin and underlying London–Brabant basement high. The key objectives of the project were to measure the equilibrium temperature in the Paleozoic basement, estimate the temperature gradient after climate impact corrections and assess the heat flow in the area. From this, estimates of temperature at depths of 2000 m could be made with a view to evaluating potential geothermal resources. From the downhole measurements, a temperature gradient of 16°C km −1 was estimated with a temperature range between 46°C and 51°C at a depth of 2000 m, considered to be consistent with other UK sites where there is no contribution from high heat production granites. The results of the Thamesmead exploration borehole suggested that the geothermal potential of the Devonian and the Paleozoic basement below London is poor, and no further work was carried out. The work has remained unpublished until now but in view of the current renewed interest in geothermal resources it is appropriate to make the work public. Although the results were not encouraging, they do remain as a contribution to the revitalized assessment of geothermal resources in the London area and the UK in general.

Hydrogeochemistry of geothermal water in Huangshadong and adjacent areas of Guangdong province: Implications for water-rock interaction

Hydrogeochemical characteristics can reflect important information on the circulation processes of geothermal fluids, reservoir temperatures, etc., which are essential for exploring geothermal field evolution and the rational development of geothermal resources. 23 sets of water samples were collected from Huangshadong and adjacent geothermal fields. Major cations and anions, hydrogen and oxygen isotopes, and 14C activities were analyzed to investigate the hydrogeochemical characteristics of geothermal fluids and their formation mechanisms. Hydrogen and oxygen isotope analysis and major element chemistry indicate that the geothermal waters in the study area are mainly recharged by meteoric water. The chemical facies of the geothermal waters are mainly Na−HCO3 and Ca−HCO3, and most of the geothermal waters have high Na+ contents, which are attributed to the involvement of albite in water-rock interaction and the replacement of Na+ in rocks by Ca2+ or Mg2+ in water. Geothermometry of geothermal waters suggests that the reservoir temperatures are between 140-150 ℃, and the geothermal water circulation depths range from 2.0 to 4.3 km. The residence time of up to 17.3ka for geothermal water likely suggests the earliest precipitation recharge during the Late Pleistocene. Major element chemistry and hydrogen and oxygen isotope systematics indicate essential information on the origins of geothermal waters and water-rock interaction processes and provide a more comprehensive understanding of the geothermal system in Huangshadong and adjacent areas of Guangdong province.

Geothermal resources and deep tectonic in Leh Ladakh (NW Himalaya), India: Inference from magnetotelluric studies

The geothermal resources and their connectivity with the deep tectonic are meaningful to understand through their structural geometry in the NW Himalayas. Therefore, over the NW-SE profiles, 23 audio Magnetotelluric (AMT) sites and over the SW-NE profile, 15 broadband Magnetotelluric (BBMT) sites were carefully chosen to provide the detailed structure. The electrical models were produced from a 2-D inversion algorithm based on the non-linear conjugate gradient method. The Chumathang-Mahe and Puga-Sumdo regions offer excellent geothermal potential as heat/fluid passes through the Mahe Fault (MF), Zildat Fault (ZF) and Kiagor Tso Fault (KTF). These faults are well revealed in the electrical models beneath the subsurface. The Puga Valley has an excellent geothermal resource at shallow depth. A ∼1000 m thick sulfide mineral body is defined with high conductivity (∼1 Ω-m). The crustal structure shows a highly conductive mid-crust beneath the Ladakh batholiths with no manifestation roots. The signs of the Indus-Tsangpo Suture Zone (ITSZ) and Shyok Suture Zone (SSZ) are well represented in the crustal model and are associated with the steep-dipping faults. The Chumathang-Mahe and Puga-Sumdo geothermal regions are connected with low resistivity body (C1) at shallow depths in the crustal model along the SW-NE profile and offer a path for deep fluid flow. The frictional heat generated in the process of the Indian plate subducting beneath the Tibetan plateau and the collision zone between India and Asia carried to melt. The high heat surface flow indicates the thermal origin of low resistivity. Thus, a ∼10 sq. km low resistivity reservoir is identified beneath the Tso Morari dome in the crustal model that overlies a resistivity feature. The high conductivity at mid-crust determined at active tectonic fabric may be potential geothermal resources yielding high well-productivity.

Advance in Detection and Management for Underground Coal Fires: A Global Technological Overview

ABSTRACT The ongoing spontaneous combustion of coal seams beneath the earth’s surface leads to the exhaustion of nonrenewable resources and poses a substantial threat to environmental integrity. Precise and efficacious monitoring of subsurface coal fire activities is an indispensable precondition for the prevention and management of coalfield conflagrations, as well as for the exploitation of geothermal energy resources. The accurate detection and localization of covert coal fires depend on the procurement and analytical assessment of distribution data for parameters that are intrinsically linked to the activities associated with coal combustion. To this end, our review work investigated the theoretical foundations, application effects, and inherent limitations of the diverse detection techniques currently available. It has been observed that the ambiguities inherent to individual detection tools can be effectively mitigated through the cross validation of findings derived from multiple detection tools. The role of detection tools can be extended to the entire process of coal fire management, yet the distinct contributions of each tool throughout the various stages of the process warrant further investigation and elucidation. In addition, the potential of emerging technologies such as machine learning algorithms and 5 G networks to promote automation and intelligence in coal fire management work was also discussed. It is our hope that the insights presented herein will serve as a valuable resource for policymakers and stakeholders in the formulation of effective strategies for the prevention and control of coalfield fires.

Geothermo‐mechanical alterations due to heat energy extraction in enhanced geothermal systems: Overview and prospective directions

AbstractGeothermal energy from deep underground (or geological) formations, with or without its combination with carbon capture and storage (CCS), can be a key technology to mitigate anthropogenic greenhouse gas emissions and meet the 2050 net‐zero carbon emission target. Geothermal resources in low‐permeability and medium‐ and high‐temperature reservoirs in sedimentary sequence require hydraulic stimulation for enhanced geothermal systems (EGS). However, fluid migration for geothermal energy in EGS or with potential CO2 storage in a CO2‐EGS are both dependent on the in situ flow pathway network created by induced fluid injection. These thermo‐mechanical interactions can be complex and induce varying alterations in the mechanical response when the working fluid is water (in EGS) or supercritical CO2 (in CO2‐EGS), which could impact the geothermal energy recovery from geological formations. Therefore, there is a need for a deeper understanding of the heat extraction process in EGS and CO2‐EGS. This study presents a systematic review of the effects of changes in mechanical properties and behavior of deep underground rocks on the induced flow pathway and heat recovery in EGS reservoirs with or without CO2 storage in CO2‐EGS. Further, we proposed waterless‐stimulated EGS as an alternative approach to improve heat energy extraction in EGS. Lastly, based on the results of our literature review and proposed ideas, we recommend promising areas of investigation that may provide more insights into understanding geothermo‐mechanics to further stimulate new research studies and accelerate the development of geothermal energy as a viable clean energy technology.

Comparative techno-economic assessment of superhot rock and conventional geothermal energy feasibility for decarbonizing India

The commercial viability of low-temperature geothermal basins is still a major stumbling block for field implementation of geothermal projects in India. Though there are several low-temperature basins, the presence of high-temperature gradient in few regions of India led to the hypothesis of testing the advanced geothermal potential in India. Therefore, this study holistically investigates the prospect of superhot rock geothermal potential in India vis-à-vis the techno-economical prospect and reservoir characteristics. Additionally, a comparative study is conducted with respect to the conventional geothermal system in the Son-Narmada-Tapti field to understand the effects of technical and economic parameters.The geothermal provinces in India can be utilized to reduce the use of fossil fuels for direct use and heating applications. However, geothermal resources suffer a setback due to high capital cost and risks associated with the feasibility of extraction process of heat energy. This study investigates the possibility of a superhot rock site to drive down the cost. To assess the technical feasibility, a comprehensive study is conducted using the reservoir heat and flow simulation for the proposed site. The study is conducted using the commercial package to obtain the heat energy that can be generated over the thirty years of injection and production. The feasibility analysis cannot be complete without the study of economic aspects. Hence, the market cost of electricity (LCOE) is estimated to understand the economic feasibility of the proposed superhot rock project. To get a better insight into the superhot rock potential, the resource potential and economic feasibility is compared with the similar system for the conventional geothermal prospect.The reservoir simulation study suggests that the dual superhot rock well system has capacity to provide 170 – 175 MWe in the region which is much higher than that of the conventional system (12 – 15 MWe). Also, it was observed that the dual well geothermal system, the waterfront does not reach the producer well over the thirty years of cold-water injection in both systems. The economic feasibility study shows that the levelized cost of electricity is most likely to be $67/MWh which is significantly less than the conventional geothermal system ($122/MWh).

Session 19. Oral Presentation for: Beetaloo gas, hydrogen and geothermal resources – insights from 3D basin modelling

Session 19. Oral Presentation for: Beetaloo gas, hydrogen and geothermal resources – insights from 3D basin modelling

Geological modeling of a tectonically controlled hydrothermal system in the southwestern part of the Pannonian basin (Croatia)

Geothermal energy is an important resource in the green economy transition. For the preservation of a geothermal resource it is crucial to assess its renewability and the sustainability of the exploitation. These aspects are influenced by the interaction among the physical, chemical, geological, and hydrogeological processes. The reconstruction of the geological assemblage allows the detailing of the geometries of the reservoir and fracture systems that influence the fluid flow and the water/rock interaction. The control of regional/local scale fault and fold systems on the development of the Daruvar hydrothermal system (DHS), located in Croatian part of the Pannonian basin, is detailed in this work. Field investigations were conducted to collect structural data on strata orientation and fault/fracture systems. The dataset was integrated with geological and geophysical data to develop composite geological profiles and a 3D geological model. Results display a pattern of generally N-S and E-W striking folds and cogenetic fracture systems with orientations parallel to the fold axes. The geological reconstruction was integrated with geophysical, hydrogeological, and geochemical data to propose a conceptual model of the DHS. The DHS is a topographically driven system hosted in a Mesozoic carbonate reservoir where E-W striking fracture systems are regional flow paths that enable infiltration of meteoric water to 1 km depth and its reheating in its reservoir area. In Daruvar, an anticline and fault/fracture systems accommodate the uplift of reservoir to shallow depths, promoting the bedrock fracturing and increase of the permeability field. These conditions favor the localized upwelling of thermal water resulting in four thermal springs (38°C and 50°C) in Daruvar city area. This work highlights the importance of employing a multidisciplinary approach to detail the complex interaction among the processes driving the geothermal resource.