Pub Date : 2026-01-09DOI: 10.1016/j.geothermics.2026.103597
Yue Shen , Yuanzhi Cheng , Zhonghe Pang
The Chabu geothermal field, located on the Xainza-Dinggye Rift, is demonstrated to be a product of the tectonic-heat flow couple under plate collision, where an extensional fault network exerts the primary control on heat and fluid transport. Based on magnetotelluric (MT) data from 76 stations, we constructed a three-dimensional resistivity model to investigate the heat source, fluid pathways, and tectonic controls on the geothermal system. The model reveals a shallow low-resistivity anomaly associated with hot spring discharge and a large-scale low-resistivity body of ∼18–20 km depth in the middle to upper crust. The low-resistivity body is interpreted as a heat source resulting from asthenospheric upwelling and partial melting of the lithosphere. These two anomalies are linked by a fault-controlled, vertically aligned low-resistivity conduit that likely serves as a channel for upward fluid migration. This channel is controlled by the intersection of the deep and large fracture in the EW direction and the SNNE direction in the region, demonstrating the significant control effect of the southern Tibetan extension structure on the migration path of thermal fluids. Studies show that the Chabu geothermal system is the product of the tectonic-heat flow couple under the background of plate collision. The extensional fault network controls both the migration of heat and the development of the hydrothermal circulation system. The results of this study provide new geophysical evidence and theoretical support for the formation mechanism and resource evaluation of the rift-type geothermal system in the South Tibet Plateau.
{"title":"Magnetotelluric imaging of tectonic control on fluid pathways and heat sources in a continental rift geothermal system, southern tibet","authors":"Yue Shen , Yuanzhi Cheng , Zhonghe Pang","doi":"10.1016/j.geothermics.2026.103597","DOIUrl":"10.1016/j.geothermics.2026.103597","url":null,"abstract":"<div><div>The Chabu geothermal field, located on the Xainza-Dinggye Rift, is demonstrated to be a product of the tectonic-heat flow couple under plate collision, where an extensional fault network exerts the primary control on heat and fluid transport. Based on magnetotelluric (MT) data from 76 stations, we constructed a three-dimensional resistivity model to investigate the heat source, fluid pathways, and tectonic controls on the geothermal system. The model reveals a shallow low-resistivity anomaly associated with hot spring discharge and a large-scale low-resistivity body of ∼18–20 km depth in the middle to upper crust. The low-resistivity body is interpreted as a heat source resulting from asthenospheric upwelling and partial melting of the lithosphere. These two anomalies are linked by a fault-controlled, vertically aligned low-resistivity conduit that likely serves as a channel for upward fluid migration. This channel is controlled by the intersection of the deep and large fracture in the EW direction and the SN<img>NE direction in the region, demonstrating the significant control effect of the southern Tibetan extension structure on the migration path of thermal fluids. Studies show that the Chabu geothermal system is the product of the tectonic-heat flow couple under the background of plate collision. The extensional fault network controls both the migration of heat and the development of the hydrothermal circulation system. The results of this study provide new geophysical evidence and theoretical support for the formation mechanism and resource evaluation of the rift-type geothermal system in the South Tibet Plateau.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103597"},"PeriodicalIF":3.9,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-07DOI: 10.1016/j.geothermics.2025.103590
Marcus L.A. do Amaral , Mayara C.O. Caldeira , Jose J.S. de Figueiredo , João Rafael B.S. Da Silveira
Geothermal energy is one of the energy resources with the potential to contribute to clean electricity generation efficiently. This study employs a Fuzzy Logic-based Multi-Criteria Decision Analysis (MCDA-Fuzzy) approach to assess the geothermal potential of an Enhanced Geothermal System (EGS) at the Utah Frontier Observatory for Research in Geothermal Energy (FORGE). The methodology integrates surface and subsurface data. Surface data include Bouguer anomaly, distance to faults and seismic epicenters, heat flow, and land surface temperature (LST), obtained from georeferenced databases and satellite imagery. Subsurface data consists of 2D sections derived from inverted magnetotelluric data, gravimetric inversion, P-wave velocity models, and basin-granitoid boundary delineation. Most data were sourced from the region’s Geothermal Data Repository (GDR). The application of the MCDA-Fuzzy methodology to surface data is compared with its application at depth to evaluate whether a surface-based assessment can provide results comparable to those obtained through geophysical modeling. The results include the construction of one geothermal potential map for the surface and six 2D maps at different depth levels, enabling a detailed spatial assessment of geothermal potential along the subsurface. We validated these maps using well-petrophysical data according to their corresponding geophysical properties. The analysis revealed that the geothermal potential estimated at the surface aligns with the distribution identified in-depth, highlighting a promising area in the eastern portion of the Utah FORGE site. It is concluded that the MCDA-Fuzzy methodology can be effectively used to assess the geothermal potential of Enhanced Geothermal Systems (EGS) using both surface data and geophysical modeling at depth, enabling the identification of promising areas for geothermal exploration with greater efficiency and lower computational cost.
{"title":"Integration of geophysical data and multicriteria decision analysis for geothermal assessment at Utah FORGE","authors":"Marcus L.A. do Amaral , Mayara C.O. Caldeira , Jose J.S. de Figueiredo , João Rafael B.S. Da Silveira","doi":"10.1016/j.geothermics.2025.103590","DOIUrl":"10.1016/j.geothermics.2025.103590","url":null,"abstract":"<div><div>Geothermal energy is one of the energy resources with the potential to contribute to clean electricity generation efficiently. This study employs a Fuzzy Logic-based Multi-Criteria Decision Analysis (MCDA-Fuzzy) approach to assess the geothermal potential of an Enhanced Geothermal System (EGS) at the Utah Frontier Observatory for Research in Geothermal Energy (FORGE). The methodology integrates surface and subsurface data. Surface data include Bouguer anomaly, distance to faults and seismic epicenters, heat flow, and land surface temperature (LST), obtained from georeferenced databases and satellite imagery. Subsurface data consists of 2D sections derived from inverted magnetotelluric data, gravimetric inversion, P-wave velocity models, and basin-granitoid boundary delineation. Most data were sourced from the region’s Geothermal Data Repository (GDR). The application of the MCDA-Fuzzy methodology to surface data is compared with its application at depth to evaluate whether a surface-based assessment can provide results comparable to those obtained through geophysical modeling. The results include the construction of one geothermal potential map for the surface and six 2D maps at different depth levels, enabling a detailed spatial assessment of geothermal potential along the subsurface. We validated these maps using well-petrophysical data according to their corresponding geophysical properties. The analysis revealed that the geothermal potential estimated at the surface aligns with the distribution identified in-depth, highlighting a promising area in the eastern portion of the Utah FORGE site. It is concluded that the MCDA-Fuzzy methodology can be effectively used to assess the geothermal potential of Enhanced Geothermal Systems (EGS) using both surface data and geophysical modeling at depth, enabling the identification of promising areas for geothermal exploration with greater efficiency and lower computational cost.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103590"},"PeriodicalIF":3.9,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The exploitation and utilization of geothermal energy necessitate a clear understanding of the genesis mechanisms of geothermal systems. The complex geological conditions result in diverse hydrochemical characteristics of enriched geothermal waters in the Gaoligong geothermal belt, southeastern Tibetan Plateau. This study employs the Self-Organizing Map (SOM) and Positive Matrix Factorization (PMF) algorithms, along with hydrochemical and hydrogen-oxygen isotope analyses, to identify the genesis mechanisms among different types of geothermal waters. Three types of geothermal water were identified in the study area (Groups 1 − 3). For Group 1, the contribution ratio of carbonate mineral dissolution (calcite, dolomite) is 37.6 %, followed by evaporite minerals (gypsum: 17.2 %, halite: 16.6 %) and silicates (28.6 %). In Group 2, silicate minerals (Ca- and Mg-rich silicates: 41.5 %, Na-rich silicates: 30.1 %) contribute the most to the components, followed by pyrite (28.4 %). For Group 3, the components are primarily derived from silicate dissolution (sandstone: 18.0 %, granite: 31.2 %), followed by geothermal gases (25.7 %) and carbonates (25.1 %). The geothermal reservoir temperatures of Groups 1 to 3 before and after mixing are 111 °C to 61 °C, 170 °C to 78 °C, and 124 °C to 63 °C, respectively. This study identified the recharge sources, quantified the sources of the major components, and assessed the reservoir temperature. Based on these findings, the corresponding genesis mechanisms with different hydrochemical characteristics were established. This study aims to deepen the understanding of magma chamber-driven geothermal systems and provide valuable support for the development and utilization of geothermal resources worldwide.
{"title":"Hydrochemical fingerprints, source apportionment and genesis mechanism of geothermal waters in the Gaoligong Geothermal Belt, southeastern Tibetan Plateau","authors":"Jinhang Huang , Xingze Li , Xingwang Chang , Xingcheng Yuan , Xun Huang , Hongyang Guo , Yunhui Zhang","doi":"10.1016/j.geothermics.2025.103577","DOIUrl":"10.1016/j.geothermics.2025.103577","url":null,"abstract":"<div><div>The exploitation and utilization of geothermal energy necessitate a clear understanding of the genesis mechanisms of geothermal systems. The complex geological conditions result in diverse hydrochemical characteristics of enriched geothermal waters in the Gaoligong geothermal belt, southeastern Tibetan Plateau. This study employs the Self-Organizing Map (SOM) and Positive Matrix Factorization (PMF) algorithms, along with hydrochemical and hydrogen-oxygen isotope analyses, to identify the genesis mechanisms among different types of geothermal waters. Three types of geothermal water were identified in the study area (Groups 1 − 3). For Group 1, the contribution ratio of carbonate mineral dissolution (calcite, dolomite) is 37.6 %, followed by evaporite minerals (gypsum: 17.2 %, halite: 16.6 %) and silicates (28.6 %). In Group 2, silicate minerals (Ca- and Mg-rich silicates: 41.5 %, Na-rich silicates: 30.1 %) contribute the most to the components, followed by pyrite (28.4 %). For Group 3, the components are primarily derived from silicate dissolution (sandstone: 18.0 %, granite: 31.2 %), followed by geothermal gases (25.7 %) and carbonates (25.1 %). The geothermal reservoir temperatures of Groups 1 to 3 before and after mixing are 111 °C to 61 °C, 170 °C to 78 °C, and 124 °C to 63 °C, respectively. This study identified the recharge sources, quantified the sources of the major components, and assessed the reservoir temperature. Based on these findings, the corresponding genesis mechanisms with different hydrochemical characteristics were established. This study aims to deepen the understanding of magma chamber-driven geothermal systems and provide valuable support for the development and utilization of geothermal resources worldwide.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103577"},"PeriodicalIF":3.9,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-05DOI: 10.1016/j.geothermics.2025.103593
Suzan Pasvanoğlu , Serkan Vural , Tekin Yeken
<div><div>The Kepekler-Ilıcaboğazı geothermal field is located in northwest Anatolia, within Balıkesir Province, and comprises both thermal waters and therapeutic clay mud (Peloids). The thermal waters emerge as springs with a temperature range from 30 to 56 °C, with discharge rates of 0.01−4 L/s along a secondary fault in the North Anatolian Fault Zone (NAFZ). Only one (BK-1) production well was drilled to a depth of 390.30 m by General Directorate of Mineral Research and Exploration of Türkiye (MTA), which has a water temperature of 64 °C and a discharge rate of 15 L/<em>sec</em>. This study investigates the chemical and isotopic characteristics of thermal and cold waters using the major ion and trace element contents as well as environmental isotope compositions. The thermal waters belong to the alkaline NaCl-type, and are characterized by pH values of 6.35 and 7.90, generally higher EC (3149–3856 µS/cm), and relatively high concentrations of Cl, Na, B, As, Rb, Li, Cs, and Sr, in contrast to the cold waters, which are primarily of the CaHCO<sub>3</sub> type. Carbonate and silicate dissolution, ion exchange, and energy loss through heat conduction are processes responsible for the origin and evolution of NaCl-type water. Thermal waters tend to have lower B/Cl ratios and strong correlations between (Cl and B, Li, and Rb) trace alkali metals and Cl due to rapid, efficient upflow pathways. These features align with high vertical permeability networks that promote efficient upflow and meteoric mixing, delineating the systems of the Kepekler-Ilıcaboğazı area. By estimating reservoir temperatures using chemical geothermometers and saturation indices, reservoir temperature estimates (75–100 °C) may be affected by conductive cooling, mixing, or partial equilibration—especially as most waters plot as "immature" on Giggenbach diagrams. Chemical equilibrium studies show that the thermal waters are in equilibrium with respect to calcite, aragonite, and quartz, while undersaturated with respect to albite, anorthite, K-feldspar, and gypsum. Thermal waters are meteoric in origin as suggested by the isotope (δ<sup>18</sup>O, δ<sup>2</sup>H, <sup>3</sup>H) composition. Carbon in thermal waters is likely to originate from metamorphic CO<sub>2</sub> or marine carbonates whereas carbon in cold waters is derived from an organic source. δ<sup>34</sup>S sulfur is derived from bacterial sulfate reduction and the dissolution of marine carbonates and sulfide minerals. The study area features a fault-controlled convection deep circulation geothermal system. Thermal waters are sourced from a resource base in the upper crust, which consists of thick granitic and metamorphic rocks that reach the surface. Using the results of hydrogeology and hydrogeochemistry, a conceptual hydrothermal model of recharge, mixing, and discharge has been proposed for the formation of the thermal waters in the study area. This is the first comprehensive geochemical and isotope-based investigati
{"title":"Geochemistry and genesis analysis of the Kepekler – Ilıcaboğazı thermal waters (Balıkesir, NW Türkiye)","authors":"Suzan Pasvanoğlu , Serkan Vural , Tekin Yeken","doi":"10.1016/j.geothermics.2025.103593","DOIUrl":"10.1016/j.geothermics.2025.103593","url":null,"abstract":"<div><div>The Kepekler-Ilıcaboğazı geothermal field is located in northwest Anatolia, within Balıkesir Province, and comprises both thermal waters and therapeutic clay mud (Peloids). The thermal waters emerge as springs with a temperature range from 30 to 56 °C, with discharge rates of 0.01−4 L/s along a secondary fault in the North Anatolian Fault Zone (NAFZ). Only one (BK-1) production well was drilled to a depth of 390.30 m by General Directorate of Mineral Research and Exploration of Türkiye (MTA), which has a water temperature of 64 °C and a discharge rate of 15 L/<em>sec</em>. This study investigates the chemical and isotopic characteristics of thermal and cold waters using the major ion and trace element contents as well as environmental isotope compositions. The thermal waters belong to the alkaline NaCl-type, and are characterized by pH values of 6.35 and 7.90, generally higher EC (3149–3856 µS/cm), and relatively high concentrations of Cl, Na, B, As, Rb, Li, Cs, and Sr, in contrast to the cold waters, which are primarily of the CaHCO<sub>3</sub> type. Carbonate and silicate dissolution, ion exchange, and energy loss through heat conduction are processes responsible for the origin and evolution of NaCl-type water. Thermal waters tend to have lower B/Cl ratios and strong correlations between (Cl and B, Li, and Rb) trace alkali metals and Cl due to rapid, efficient upflow pathways. These features align with high vertical permeability networks that promote efficient upflow and meteoric mixing, delineating the systems of the Kepekler-Ilıcaboğazı area. By estimating reservoir temperatures using chemical geothermometers and saturation indices, reservoir temperature estimates (75–100 °C) may be affected by conductive cooling, mixing, or partial equilibration—especially as most waters plot as \"immature\" on Giggenbach diagrams. Chemical equilibrium studies show that the thermal waters are in equilibrium with respect to calcite, aragonite, and quartz, while undersaturated with respect to albite, anorthite, K-feldspar, and gypsum. Thermal waters are meteoric in origin as suggested by the isotope (δ<sup>18</sup>O, δ<sup>2</sup>H, <sup>3</sup>H) composition. Carbon in thermal waters is likely to originate from metamorphic CO<sub>2</sub> or marine carbonates whereas carbon in cold waters is derived from an organic source. δ<sup>34</sup>S sulfur is derived from bacterial sulfate reduction and the dissolution of marine carbonates and sulfide minerals. The study area features a fault-controlled convection deep circulation geothermal system. Thermal waters are sourced from a resource base in the upper crust, which consists of thick granitic and metamorphic rocks that reach the surface. Using the results of hydrogeology and hydrogeochemistry, a conceptual hydrothermal model of recharge, mixing, and discharge has been proposed for the formation of the thermal waters in the study area. This is the first comprehensive geochemical and isotope-based investigati","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103593"},"PeriodicalIF":3.9,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-04DOI: 10.1016/j.geothermics.2025.103568
Chenhua Li , Xiaocheng Zhou , Miao He , Zhaojun Zeng , Yuwen Wang , Jiao Tian , Yucong Yan , Bingyu Yao , Hejun Su , Ruigang Li
Geochemical variations in thermal spring compositions are sensitive to changes in regional stress, temperature, and space conditions, which are indicators of seismic and tectonic activities. However, the temporal and spatial variations in water chemistry components and their inducing mechanisms are insufficiently understood. This study aims to evaluate the effective temporal coincidence/lag of seismic events based on the long-term continuous water chemistry monitoring of seismic areas and draw attention to water chemistry changes in thermal waters during earthquake hazard monitoring. We investigated the major elements, trace elements, and hydrogen and oxygen isotopes of 21 thermal springs along the Lancang–Gengma fault (LGF) zone, which is in a highly deformed, seismically active area of the Southeastern margin of the Tibetan Plateau. In the LGF zone, the temperatures of the studied thermal springs range from 44.7°C to 96.2°C. The reservoir temperatures range from 91°C to 195°C and the reservoir depth range from 4–9 km. According to the spatiotemporal chemical variations from two-year regular monitoring of Na+, Cl−, F−, SO42−, Li, B, δD, and δ18O in five thermal springs, the thermal springs in these fault-controlled areas are sensitive and responsive to seismic activity. Different tectonic regions exhibit significant and diverse short-term precursory anomalies in water chemistry before earthquakes with M ≥ 5.0. Their characteristics and mechanisms are region-specific, and the study area is divided into two monitoring capacity range areas. Area 1: The MG, MM and XF monitoring points located on the Baoshan block are highly sensitive to seismic responses in the SW direction of the study area. For example, continuous Na⁺, Cl−, SO42−and F− anomalies were observed in MG, MM and XF before the ML5.0 and ML5.9 Myanmar earthquakes (southwest of the study area). Area 2: The NKL and EL monitoring points located on the Simao block are highly sensitive to seismic responses in the SE direction. For instance, the Na⁺ concentrations in EL and NKL sharply increased above the normal threshold before the ML6.2 Laos earthquake and ML5.0 Honghe earthquake. Notably, significant spatial directional differences in fluid chemical responses to earthquakes were observed. This directional difference may be related to the complexity of the regional stress field in the area and the local characteristics of fault activities. The chemical composition changes of these thermal springs during fluid circulation in the LGF can be a good tracer of seismic activity.
{"title":"Tectonic controls and earthquake response of thermal fluid geochemistry in southern Yunnan, southeastern Tibetan Plateau","authors":"Chenhua Li , Xiaocheng Zhou , Miao He , Zhaojun Zeng , Yuwen Wang , Jiao Tian , Yucong Yan , Bingyu Yao , Hejun Su , Ruigang Li","doi":"10.1016/j.geothermics.2025.103568","DOIUrl":"10.1016/j.geothermics.2025.103568","url":null,"abstract":"<div><div>Geochemical variations in thermal spring compositions are sensitive to changes in regional stress, temperature, and space conditions, which are indicators of seismic and tectonic activities. However, the temporal and spatial variations in water chemistry components and their inducing mechanisms are insufficiently understood. This study aims to evaluate the effective temporal coincidence/lag of seismic events based on the long-term continuous water chemistry monitoring of seismic areas and draw attention to water chemistry changes in thermal waters during earthquake hazard monitoring. We investigated the major elements, trace elements, and hydrogen and oxygen isotopes of 21 thermal springs along the Lancang–Gengma fault (LGF) zone, which is in a highly deformed, seismically active area of the Southeastern margin of the Tibetan Plateau. In the LGF zone, the temperatures of the studied thermal springs range from 44.7°C to 96.2°C. The reservoir temperatures range from 91°C to 195°C and the reservoir depth range from 4–9 km. According to the spatiotemporal chemical variations from two-year regular monitoring of Na<sup>+</sup>, Cl<sup>−</sup>, F<sup>−</sup>, SO<sub>4</sub><sup>2−</sup>, Li, B, δD, and δ<sup>18</sup>O in five thermal springs, the thermal springs in these fault-controlled areas are sensitive and responsive to seismic activity. Different tectonic regions exhibit significant and diverse short-term precursory anomalies in water chemistry before earthquakes with <em>M</em> ≥ 5.0. Their characteristics and mechanisms are region-specific, and the study area is divided into two monitoring capacity range areas. Area 1: The MG, MM and XF monitoring points located on the Baoshan block are highly sensitive to seismic responses in the SW direction of the study area. For example, continuous Na⁺, Cl<sup>−</sup>, SO<sub>4</sub><sup>2−</sup>and F<sup>−</sup> anomalies were observed in MG, MM and XF before the <em>M</em><sub>L</sub>5.0 and <em>M</em><sub>L</sub>5.9 Myanmar earthquakes (southwest of the study area). Area 2: The NKL and EL monitoring points located on the Simao block are highly sensitive to seismic responses in the SE direction. For instance, the Na⁺ concentrations in EL and NKL sharply increased above the normal threshold before the <em>M</em><sub>L</sub>6.2 Laos earthquake and <em>M</em><sub>L</sub>5.0 Honghe earthquake. Notably, significant spatial directional differences in fluid chemical responses to earthquakes were observed. This directional difference may be related to the complexity of the regional stress field in the area and the local characteristics of fault activities. The chemical composition changes of these thermal springs during fluid circulation in the LGF can be a good tracer of seismic activity.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103568"},"PeriodicalIF":3.9,"publicationDate":"2026-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145925314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-03DOI: 10.1016/j.geothermics.2025.103595
Ana M.B. Domingues , Andre L. Razera , Jairo V.A. Ramalho , Michel K. Rodrigues , Honório J. Fernando , Liércio A. Isoldi , Elizaldo D. dos Santos
This study presents a numerical investigation of the performance of Earth-Air Heat Exchanger (EAHE) systems equipped with galvanized structures surrounding the duct. Two geometric configurations (T- and Y-shaped) are evaluated using the Constructal Design method combined with the Exhaustive Search technique. The analysis considers the EAHE thermal potential (TPEAHE) and the maximum annual efficiency (θmax), along with a multi-objective assessment based on the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), in which TPEAHE is treated as a benefit criterion and installation depth as a cost criterion. The results indicate that intermediate installation depths (between 3.7 m and 5.0 m) provide better thermal performance, while deeper configurations do not necessarily result in higher TPEAHE values. The T-shaped geometry with a balanced proportion between the vertical and horizontal branches, and the Y-shaped geometry with a branching angle of 140 degrees, exhibited superior performance, with improvements above 10% and 5%, respectively, compared to the least favorable geometries. The optimized Y-shaped configuration reached θmax = 72.0%, achieving a 66.3% gain compared to a conventional case (without galvanized material). The multi-objective analysis demonstrated that there is no universally optimal geometry, but rather a set of effective solutions that emerge depending on the priorities assigned to the system's objectives.
{"title":"Performance analysis and geometric evaluation of galvanized T- and Y-Shapes for earth-air heat exchangers using constructal design","authors":"Ana M.B. Domingues , Andre L. Razera , Jairo V.A. Ramalho , Michel K. Rodrigues , Honório J. Fernando , Liércio A. Isoldi , Elizaldo D. dos Santos","doi":"10.1016/j.geothermics.2025.103595","DOIUrl":"10.1016/j.geothermics.2025.103595","url":null,"abstract":"<div><div>This study presents a numerical investigation of the performance of Earth-Air Heat Exchanger (EAHE) systems equipped with galvanized structures surrounding the duct. Two geometric configurations (T- and Y-shaped) are evaluated using the Constructal Design method combined with the Exhaustive Search technique. The analysis considers the EAHE thermal potential (<em>TP<sub>EAHE</sub></em>) and the maximum annual efficiency (<em>θ<sub>max</sub></em>), along with a multi-objective assessment based on the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), in which <em>TP<sub>EAHE</sub></em> is treated as a benefit criterion and installation depth as a cost criterion. The results indicate that intermediate installation depths (between 3.7 m and 5.0 m) provide better thermal performance, while deeper configurations do not necessarily result in higher <em>TP<sub>EAHE</sub></em> values. The T-shaped geometry with a balanced proportion between the vertical and horizontal branches, and the Y-shaped geometry with a branching angle of 140 degrees, exhibited superior performance, with improvements above 10% and 5%, respectively, compared to the least favorable geometries. The optimized Y-shaped configuration reached <em>θ<sub>max</sub></em> = 72.0%, achieving a 66.3% gain compared to a conventional case (without galvanized material). The multi-objective analysis demonstrated that there is no universally optimal geometry, but rather a set of effective solutions that emerge depending on the priorities assigned to the system's objectives.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103595"},"PeriodicalIF":3.9,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-29DOI: 10.1016/j.geothermics.2025.103581
Lucas Bofill , Gerhard Schäfer , Guilherme Bozetti , Jean-François Ghienne , Mathieu Schuster
Sandstone aquifers lacking mudstone interbeds are often considered homogeneous. However, depositional processes and diagenesis can generate significant permeability contrasts without notable variations in granulometry. Capturing this heterogeneity in flow models is essential but challenging. Outcrop studies provide valuable analogues for subsurface conditions, revealing sedimentary architectures and facies distributions not observable from borehole data alone. This study focuses on the Lower Grès Vosgien formation in eastern France, an important aquifer hosting lithium-rich geothermal brines in the Upper Rhine Graben, deposited by braided fluvial and aeolian systems during the Lower Triassic. This work aims to evaluate the influence of decimetre- to metre-scale sandstone features on advective transport modelling, through a two-dimensional conceptual model developed using a digital outcrop model and sedimentary facies analysis. Six progressively simplified hydrostratigraphic models are tested to assess how heterogeneity and its representation affect particle residence times, breakthrough curves, longitudinal macrodispersivity, and upscaled anisotropy. Results indicate that distinguishing fluvial- and aeolian-related sandstones significantly influences both horizontal and vertical advective flow. Failure to discretise individual fluvial facies and reliance on deterministic hydraulic conductivity values led to the underestimation of preferential flow pathways, delaying the prediction of first particle arrivals. Moreover, the discretisation between fluvial and aeolian-related deposits significantly affects macrodispersion results and yields considerable anisotropy when the conceptual model is upscaled. The strong coupling between advective flow with heat transfer and solute transport underscores the critical role of the observed sedimentary heterogeneity on the accurate understanding of lithium-rich geothermal brines circulation in the matrix porosity of the Lower Triassic sedimentary successions in the Upper Rhine Graben reservoirs.
{"title":"From Outcrop to Groundwater Flow: The Impact of Overlooked Heterogeneity on Advective Transport in Lower Triassic Sandstones, Eastern France","authors":"Lucas Bofill , Gerhard Schäfer , Guilherme Bozetti , Jean-François Ghienne , Mathieu Schuster","doi":"10.1016/j.geothermics.2025.103581","DOIUrl":"10.1016/j.geothermics.2025.103581","url":null,"abstract":"<div><div>Sandstone aquifers lacking mudstone interbeds are often considered homogeneous. However, depositional processes and diagenesis can generate significant permeability contrasts without notable variations in granulometry. Capturing this heterogeneity in flow models is essential but challenging. Outcrop studies provide valuable analogues for subsurface conditions, revealing sedimentary architectures and facies distributions not observable from borehole data alone. This study focuses on the Lower Grès Vosgien formation in eastern France, an important aquifer hosting lithium-rich geothermal brines in the Upper Rhine Graben, deposited by braided fluvial and aeolian systems during the Lower Triassic. This work aims to evaluate the influence of decimetre- to metre-scale sandstone features on advective transport modelling, through a two-dimensional conceptual model developed using a digital outcrop model and sedimentary facies analysis. Six progressively simplified hydrostratigraphic models are tested to assess how heterogeneity and its representation affect particle residence times, breakthrough curves, longitudinal macrodispersivity, and upscaled anisotropy. Results indicate that distinguishing fluvial- and aeolian-related sandstones significantly influences both horizontal and vertical advective flow. Failure to discretise individual fluvial facies and reliance on deterministic hydraulic conductivity values led to the underestimation of preferential flow pathways, delaying the prediction of first particle arrivals. Moreover, the discretisation between fluvial and aeolian-related deposits significantly affects macrodispersion results and yields considerable anisotropy when the conceptual model is upscaled. The strong coupling between advective flow with heat transfer and solute transport underscores the critical role of the observed sedimentary heterogeneity on the accurate understanding of lithium-rich geothermal brines circulation in the matrix porosity of the Lower Triassic sedimentary successions in the Upper Rhine Graben reservoirs.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103581"},"PeriodicalIF":3.9,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-27DOI: 10.1016/j.geothermics.2025.103588
Peng Dai , Tobias Dalton , Paul Eizenhoefer , Sicong Zheng , Kongyou Wu , Zhenhai Zhang , Yuntao Song , Shengdong Wang , Gege Zhang , Yimin She
The distribution of geothermal resources is strongly influenced by the surface–subsurface structural framework of a region, yet the quantitative coupling between fault systems and geothermal reservoirs remains insufficiently constrained in extensional basins. In this study, a multi-method approach integrating gas geochemistry, controlled-source electromagnetic, and geothermal well logging was applied to the Boye area to elucidate its structural–geothermal mechanism. The results reveal that the major NE–SW-trending listric normal faults with NW or SE dips dominate the structural framework and govern the spatial distribution of heat sources, reservoirs, and migration pathways. The deep carbonate geothermal reservoirs in Boye mainly consist of Middle Proterozoic (Jxw and Chg) dolomite, characterized by abundant fractures and cavities that provide effective storage space and enhance convective heat transfer, consistent with the observed reduction in geothermal gradient observed in borehole data. Geothermal accumulation in Boye are controlled by the integrated effects of source, migration, reservoir, and cap structures. Source structures facilitate the upward transfer of crust–mantle heat flow. Migration structures, comprising faults and unconformities, act as conduits that link deep sources with reservoirs. Reservoir structures include both fault-related and intra-reservoir fractures and cavities, providing favorable storage and flow conditions. Cap structures, affected by Cenozoic faulting, both govern meteoric recharge and thermal retention. This study establishes a structural–geothermal framework for the Boye area, demonstrating how extensional fault systems control heat and fluid migration, and providing a practical methodological reference for geothermal exploration in similar tectonic settings.
{"title":"Structural controls on the geothermal reservoir across the Boye Area of Jizhong Depression, Northern China","authors":"Peng Dai , Tobias Dalton , Paul Eizenhoefer , Sicong Zheng , Kongyou Wu , Zhenhai Zhang , Yuntao Song , Shengdong Wang , Gege Zhang , Yimin She","doi":"10.1016/j.geothermics.2025.103588","DOIUrl":"10.1016/j.geothermics.2025.103588","url":null,"abstract":"<div><div>The distribution of geothermal resources is strongly influenced by the surface–subsurface structural framework of a region, yet the quantitative coupling between fault systems and geothermal reservoirs remains insufficiently constrained in extensional basins. In this study, a multi-method approach integrating gas geochemistry, controlled-source electromagnetic, and geothermal well logging was applied to the Boye area to elucidate its structural–geothermal mechanism. The results reveal that the major NE–SW-trending listric normal faults with NW or SE dips dominate the structural framework and govern the spatial distribution of heat sources, reservoirs, and migration pathways. The deep carbonate geothermal reservoirs in Boye mainly consist of Middle Proterozoic (Jxw and Chg) dolomite, characterized by abundant fractures and cavities that provide effective storage space and enhance convective heat transfer, consistent with the observed reduction in geothermal gradient observed in borehole data. Geothermal accumulation in Boye are controlled by the integrated effects of source, migration, reservoir, and cap structures. Source structures facilitate the upward transfer of crust–mantle heat flow. Migration structures, comprising faults and unconformities, act as conduits that link deep sources with reservoirs. Reservoir structures include both fault-related and intra-reservoir fractures and cavities, providing favorable storage and flow conditions. Cap structures, affected by Cenozoic faulting, both govern meteoric recharge and thermal retention. This study establishes a structural–geothermal framework for the Boye area, demonstrating how extensional fault systems control heat and fluid migration, and providing a practical methodological reference for geothermal exploration in similar tectonic settings.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103588"},"PeriodicalIF":3.9,"publicationDate":"2025-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145839919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The transition toward sustainable building heating is vital for achieving carbon neutrality. Medium-deep borehole heat exchanger (BHE) systems provide a promising geothermal solution, but large-scale planning is hindered by the high computational demand of traditional simulations for performance prediction across diverse geologies. This study integrates machine learning (ML) algorithms with a validated finite-volume model to develop an efficient framework for evaluating the long-term thermal performance and potential of BHEs. Focusing on five major Chinese cities (Hebei, Tianjin, Shandong, Henan, and Shaanxi), the framework analyzes the impact of key geological and operating parameters (depth: 2000–3000 m; flow rate: 20–40 m³/h; inlet temperature: 5–20 °C). Among three ML algorithms—Levenberg-Marquardt (LM), Bayesian Regularization (BR), and Quantized Conjugate Gradient (QCG)—the LM algorithm achieved superior accuracy (MSE = 3.0261, R = 0.99965) and robustness against overfitting. Regional analysis highlights the crucial influence of local geology. Henan exhibits the highest heat extraction (235.5 kW) with moderate 10-year decay (5.0 %), while Shaanxi shows the steepest decline. Economically, geothermal deployment can reduce heating costs by 60–95 % and CO₂ emissions by 73–89 % compared to conventional coal systems. This ML-driven framework provides rapid, data-informed decision-making for low-carbon heating investment and geothermal integration in sustainable development.
{"title":"Machine learning-based assessment of medium-deep geothermal energy potential in five chinese cities","authors":"Guosheng Jia, Jianke Hao, Xiaofeng Peng, Pei Wang, Zhibin Zhang, Meng Zhang, Liwen Jin","doi":"10.1016/j.geothermics.2025.103578","DOIUrl":"10.1016/j.geothermics.2025.103578","url":null,"abstract":"<div><div>The transition toward sustainable building heating is vital for achieving carbon neutrality. Medium-deep borehole heat exchanger (BHE) systems provide a promising geothermal solution, but large-scale planning is hindered by the high computational demand of traditional simulations for performance prediction across diverse geologies. This study integrates machine learning (ML) algorithms with a validated finite-volume model to develop an efficient framework for evaluating the long-term thermal performance and potential of BHEs. Focusing on five major Chinese cities (Hebei, Tianjin, Shandong, Henan, and Shaanxi), the framework analyzes the impact of key geological and operating parameters (depth: 2000–3000 m; flow rate: 20–40 m³/h; inlet temperature: 5–20 °C). Among three ML algorithms—Levenberg-Marquardt (LM), Bayesian Regularization (BR), and Quantized Conjugate Gradient (QCG)—the LM algorithm achieved superior accuracy (MSE = 3.0261, <em>R</em> = 0.99965) and robustness against overfitting. Regional analysis highlights the crucial influence of local geology. Henan exhibits the highest heat extraction (235.5 kW) with moderate 10-year decay (5.0 %), while Shaanxi shows the steepest decline. Economically, geothermal deployment can reduce heating costs by 60–95 % and CO₂ emissions by 73–89 % compared to conventional coal systems. This ML-driven framework provides rapid, data-informed decision-making for low-carbon heating investment and geothermal integration in sustainable development.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103578"},"PeriodicalIF":3.9,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-26DOI: 10.1016/j.geothermics.2025.103580
Lingkan Finna Christi , Mrityunjay Singh , Ingo Sass , Ben Norden , Günter Zimmermann , Maximilian Frick , Monika Hölzel , Hannes Hofmann
This study demonstrates the potential of Deep Borehole Heat Exchangers (DBHEs) technology to unlock low-risk, cost-effective geothermal energy in Groß Schönebeck by repurposing existing wells. The well doublet features approximately 1.5 km of the Zechstein formation, a thermally conductive and impermeable formation ideal for DBHE applications. A numerical simulation using CMG STARS was used to optimize the installation of a DBHE to a depth of 3800 m MD. At this completion depth, both wells achieved thermal power ranging from 500–750 kilowatts (kW) and outlet temperatures in the range of 49–67 °C with the flow rates ranging from 10 to 25 m3 h−1 and inlet temperatures between 10–25 °C. With the model, we explored the relationship between tubing dimensions and materials, as well as the impact of varying operational parameters on the performance of the DBHEs. Our analysis confirms direct heating is the most suitable application, with a Levelized Cost of Heat (LCOH) of 7-14 ct €/kWh within the given operational parameters. While electricity generation is not feasible, the study highlights a cost-effective, low-risk geothermal heating solution by repurposing existing wells as DBHEs. Key requirements include deployment of minimum 2.88”/2.44” (OD/ID) vacuum-insulated tubing (or equivalent) with low thermal conductivity ( 0.06 W m−1 K−1), and subsequent field validation of heat transfer parameters. This approach minimizes investment and risk by utilizing existing infrastructure, but requires close proximity between the heat source and the consumer. Future research and feasibility studies should prioritize well integrity and seamless integration with surface infrastructure and district heating networks.
该研究展示了深孔热交换器（DBHEs）技术的潜力，通过重新利用现有井，在Groß Schönebeck开发低风险、低成本的地热能。该双井的特点是约1.5公里的Zechstein地层，这是一种导热、不渗透的地层，非常适合DBHE应用。使用CMG STARS进行数值模拟，优化DBHE的安装深度为3800 m MD。在该完井深度，两口井的热功率为500-750千瓦，出口温度为49-67℃，流量为10 - 25 m3 h - 1，进口温度为10 - 25℃。通过该模型，我们探索了油管尺寸与材料之间的关系，以及不同操作参数对dbh性能的影响。我们的分析证实，直接加热是最合适的应用，在给定的运行参数下，平均热成本（LCOH）为7-14 ct€/kWh。虽然发电是不可行的，但该研究强调了一种经济、低风险的地热加热解决方案，即将现有井重新利用为dbh。关键要求包括部署至少2.88 " /2.44 "（外径/内径）真空绝缘管（或同等材料），具有低导热系数（≤0.06 W m−1 K−1），以及随后的传热参数现场验证。这种方法通过利用现有的基础设施将投资和风险降到最低，但需要热源和消费者之间的距离很近。未来的研究和可行性研究应优先考虑井的完整性和与地面基础设施和区域供热网络的无缝集成。
{"title":"Design optimization of Deep Borehole Heat Exchangers (DBHEs) for well retrofitting","authors":"Lingkan Finna Christi , Mrityunjay Singh , Ingo Sass , Ben Norden , Günter Zimmermann , Maximilian Frick , Monika Hölzel , Hannes Hofmann","doi":"10.1016/j.geothermics.2025.103580","DOIUrl":"10.1016/j.geothermics.2025.103580","url":null,"abstract":"<div><div>This study demonstrates the potential of Deep Borehole Heat Exchangers (DBHEs) technology to unlock low-risk, cost-effective geothermal energy in Groß Schönebeck by repurposing existing wells. The well doublet features approximately 1.5 km of the Zechstein formation, a thermally conductive and impermeable formation ideal for DBHE applications. A numerical simulation using CMG STARS was used to optimize the installation of a DBHE to a depth of 3800 m MD. At this completion depth, both wells achieved thermal power ranging from 500–750 kilowatts (kW) and outlet temperatures in the range of 49–67 °C with the flow rates ranging from 10 to 25 m<sup>3</sup> <!-->h<sup>−1</sup> and inlet temperatures between 10–25 °C. With the model, we explored the relationship between tubing dimensions and materials, as well as the impact of varying operational parameters on the performance of the DBHEs. Our analysis confirms direct heating is the most suitable application, with a Levelized Cost of Heat (LCOH) of 7-14 ct €/kWh within the given operational parameters. While electricity generation is not feasible, the study highlights a cost-effective, low-risk geothermal heating solution by repurposing existing wells as DBHEs. Key requirements include deployment of minimum 2.88”/2.44” (OD/ID) vacuum-insulated tubing (or equivalent) with low thermal conductivity (<span><math><mo>≤</mo></math></span> 0.06<!--> <!-->W<!--> <!-->m<sup>−1</sup> <!-->K<sup>−1</sup>), and subsequent field validation of heat transfer parameters. This approach minimizes investment and risk by utilizing existing infrastructure, but requires close proximity between the heat source and the consumer. Future research and feasibility studies should prioritize well integrity and seamless integration with surface infrastructure and district heating networks.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"136 ","pages":"Article 103580"},"PeriodicalIF":3.9,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145839918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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