Geothermal Province Research Articles

Evaluation of alteration in the geothermal province west of Cappadocia, Türkiye: Mineralogical, petrographical, geochemical, and remote sensing data

Abstract This study determines the mineralogical, petrographical, and geochemical properties of the rocks outcropping in geothermal areas west of the Cappadocia geothermal region. These areas include Ziga, Narlıgöl, Belisırma, Ilısu, and Sivrihisar. The study reveals their hydrothermal alteration characteristics. Also, the study aims to determine the zones of hydrothermal alterations using remote sensing. Rock samples from geothermal areas were performed using optical microscopy, X-ray diffraction (XRD), scanning electron microscopy, X-ray fluorescence spectroscopy, and inductively coupled plasma–mass spectrometry techniques for the determination of mineralogical assemblages and major, trace and REE's analyses. Rock samples, determined as ignimbrites and tuff, exhibit intensive alterations. XRD analysis determined the association of alteration minerals. The dominant clay minerals were kaolinite, montmorillonite, and illite. The analyses and mineral associations are compatible with argillic, mid-argillic alteration, and silicification zones. Alteration zones were identified by classifying the ASTER satellite images of kaolinite, illite, and montmorillonite using the CROSTA technique. The alteration zones observed in this study are close to existing geothermal areas. In addition, different regions with these alterations have been identified within the study area and are expected to be a valuable reference for future geothermal exploration.

An assessment of prospects of geothermal energy in India for energy sustanability

The search for indigenous, renewable, environment-friendly, and sustainable energy resources has increased globally during the past few decades. Geothermal energy is one such ubiquitous source of energy, having the potential to become an alternate energy resource with a reduced carbon footprint. In this study, eight crucial characteristic parameters, i.e., heat flow, thermal gradient, Curie point depth, lithology, basement depth, crustal thickness, and seismicity, were integrated into a multi-criteria decision model framework to identify areas that may have the potential for geothermal energy in India. The weights of various parameters estimated using AHP are in the order of heat flow (∼ 0.252), followed by the Curie point depth (∼ 0.195), thermal gradient (∼ 0.173), and crustal thickness. Our analysis indicates that the geothermal province in the Himalayas (including the NW and NE regions), SONATA lineaments, central parts, and some parts of the west coasts and Mahanadi graben may have better prospects of geothermal energy compared to other tectonic provinces. We find that ∼14.86%, and ∼21.98 % of the study region have extremely high to high geothermal potential. About ∼ 27.18 % of the region have medium geothermal prospects, whereas ∼ 11.78 % and 24.20 % of the region have very low to low potential for geothermal energy.

Selection of suitable geothermometers for predicting the subsurface temperatures with higher accuracy: A study based on globally distributed geothermal field data

Subsurface reservoir temperature of a geothermal province is popularly estimated using various geothermometers but it is necessary to examine the suitability of them. Present work studies the performances of five popular geothermometers Na-K, Na-K-Ca, Quartz, Chalcedony and K-Mg to forecast the reservoir temperature of 148 geothermal springs located in different parts of the world. The predicted temperature of the geothermometers have been compared with the bottom whole temperature (BHT) of the wells drilled in those geothermal fields to check the accuracy of the predictions.The results show that performance of a particular geothermometer is significantly affected by the type of rocks in a geothermal reservoir. Na-K geothermometer provides highest accuracy for the basaltic and sandstone reservoir rocks with average errors 15 % and 11 % respectively. The quartz geothermometer also provides almost equally good prediction for sandstone. The best result for a granitic reservoir rock is obtained by Na-K-Ca with an average error about 15 %. The carbonate reservoir rocks are the most difficult reservoir rock to use any geothermometer as lowest error of prediction using any geothermometer is about 26 %. The chalcedony performed the poorest among all geothermometers and is not recommended for any reservoir rock types under considerations. Thus, the study on global geothermal fields shows that the reservoir rock type must be considered to select a geothermometer else it may cause very high error in prediction of reservoir temperature. However, none of the geothermometer could produce error less than 10 %. It is worth noting that the present study though establishes the suitability of a geothermometer for a particular lithology, it does not explore the rationale for such a suitability.

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).

Trace element geochemistry of high-temperature geothermal waters in the Yunnan-Tibet geothermal province, Southwest China

To investigate the origins of the trace elements and related geochemical processes, seven representative geothermal systems in southern Tibet and one in western Yunnan were selected. The geothermal waters were divided into acidic and neutral-to-alkaline in magmatic geothermal systems and neutral-to-alkaline in non-magmatic geothermal systems. Acidic geothermal waters exhibit low concentrations of most trace elements. In the neutral-to-alkaline geothermal waters in magmatic geothermal systems, the composition of most trace elements is determined by the water–rock interactions, along with the solubility of secondary minerals, with magmatic fluids contributing to other trace elements (e.g., B, As, Sb, Mo and W). As for the geothermal waters of non-magmatic geothermal systems, trace elements are primarily derived from carbonate reservoir rock dissolution. Trace elements of magmatic origin are more abundant in the Tibetan geothermal waters than in those of Yunnan, which results from the varied chemical composition of their underlying magma chambers. Our findings indicate that the trace element geochemistry has the potential to identify the genesis of geothermal systems.

Magnetotelluric images of the medium enthalpy Bakreswar geothermal province within a granitic gneissic complex, Eastern Indian Peninsula

AbstractThe Bakreswar geothermal province represents a medium enthalpy geothermal system with its Bakreswar and Tantloie hot springs. It lies within the Chotanagpur Granite Gneissic Complex in the eastern part of the Indian Peninsula. The province has a high heat flow and a high geothermal gradient of 90°C/km. Magnetotelluric data from 95 sites in a frequency range of 10 kHz–10 Hz were acquired over the Bakreswar geothermal province to obtain an electrical conductivity model and map the geothermal reservoir with its fluid pathways and related geological structures. Subsurface conductivity models obtained from three‐dimensional inversions of the Magnetotelluric data exhibit several prominent anomalies, which are supplemented by gravity results. The conductivity model maps three features which act as a conduit (a) a northwest–southeast trending feature, (b) an east–west trending feature to the south of the northwest–southeast trending feature (which lies 1 km north of the Oil and Natural Gas Corporation fault marked by previous studies) and (c) shallow conducting features close to Bakreswar hot spring. The northwest–southeast trending feature coincides with the boundary of the high‐density intrusive block. This northwest–southeast trending feature provides the pathway for the meteoric water to reach a maximum depth of 2.7 km, where it gets heated by interacting with deep‐seated structures and then it rises towards the surface. The radiogenic process occurring within the granites of Chotanagpur Granite Gneissic Complex provides the heat responsible for heating the meteoric water. The northwest–southeast and east–west trending features are responsible for the transport of meteoric water to deeper depths and then towards the shallow regions of the Earth. The near surface features close to the Bakreswar hot spring are responsible for carrying the water further towards the hot spring. The resistivity of these structures plotted as a function of salinity and temperatures for saline crustal fluids suggests the involvement of meteoric water. Further, applying Archie's law to this resistivity suggests that the conduit path has a porosity greater than 10%. This study successfully maps the anomalous structures which might foster the migration of geothermal fluid in Bakreswar geothermal province.

Phylogenetically and physiologically diverse methanogenic archaea inhabit the Indian hot spring environments.

Mesophilic and thermophilic methanogens belonging to the hydrogenotrophic, methylotrophic, and acetotrophic groups were isolated from Indian hot spring environments using BY and BCYT growth media. Following initial Hinf I-based PCR-RFLP screening, 70 methanogens were sequenced to ascertain their identity. These methanogens were phylogenetically and physiologically diverse and represented different taxa distributed across three physiological groups, i.e., hydrogenotrophs (53), methylotrophs (14) and acetotrophs (3). Overall, methanogens representing three families, five genera, and ten species, including two putative novel species, were recognized. The highest number and diversity of methanogens was observed at 40℃, dominated by Methanobacterium (10; 3 species), Methanosarcina (9; 3 species), Methanothermobacter (7; 2 species), Methanomethylovorans (5; 1 species) and Methanoculleus (3; 1 species). Both putative novel methanogen species were isolated at 40℃ and belonged to the genera Methanosarcina and Methanobacterium. At 55℃, limited diversity was observed, and resulted in the isolation of only two genera of methanogens, i.e., Methanothermobacter (28; 2 species) and Methanosarcina (4; 1 species). At 70℃, only members of the genus Methanothermobacter (5; 2 species) were isolated, whereas no methanogen could be cultured at 85℃. Ours is the first study that documents the extensive range of cultivable methanogenic archaea inhabiting hot springs across various geothermal provinces of India.

Unraveling the paleo-marine signature in saline thermal waters of Cambay rift basin, Western India: Insights from geochemistry and multi isotopic (B, O and H) analysis

Cambay rift basin is the only geothermal province in India that hosts several saline thermal water manifestations having EC values varying from 525 to 10,860 μS/cm. Various ionic ratios (Na/Cl, Br/Cl, Ca/(SO4 + HCO3), SO4/Cl) as well as boron isotopic composition (δ11B = 40.5 to 46 ‰) clearly ascribes the presence of fossil (relics of evaporated seawater) seawater as origin of increased salinity in the majority of thermal waters. Depleted isotopic (δ18O, δ2H) composition of these thermal waters also substantiates the presence of paleowater in these systems. In rest of the thermal waters, agricultural return flow is found to be source of dissolved solutes as confirmed from different bivariate plots such as B/Cl vs. Br/Cl and δ11B vs. B/Cl as well as from ionic ratios. This study thus provides the diagnostic tools to elucidate the source of variable salinity in the thermal waters circulating in the Cambay rift basin, India.

Tracing hydrothermal mineral thenardite in geysers/hot springs of North-western Himalayan belt, Ladakh Geothermal Province, India by hydrogeochemistry, fluid-mineral equilibria and isotopic studies

The present study highlights the first evidence of hydrothermal mineral Thenardite (Na2SO4) from Puga geothermal area, North-western Himalayan belt in Ladakh Geothermal Province, India, which is unequivocal evidence for the presence of high-temperature hydrothermal fluid activity from one of the thickest crust areas of the Earth. The Puga geothermal belt illustrates a fault-bounded hydrothermal system with a clearly defined conductive zone, coinciding with Kiagar Tso fault typically exemplifying a shallow-level medium enthalpic geothermal reservoir. The hydrogeochemistry suggests that thermal and non-thermal waters are of Na-Cl-HCO3 and Ca-Mg-HCO3 type, respectively, with neutral to near alkaline pH. The silica and cation geothermometry reveal sub-surface temperatures around 150 °C and 250 °C, respectively, at shallow depth; however, >250 °C is anticipated at the deepest levels (~3 km). Stable isotope (δD and δ18O) studies explicate depletion of isotopic content for thermal waters over Puga river water and radiogenic isotope (3H) suggests matured thermal waters with ongoing water-rock interactions. The recharge altitude estimation and physiographic studies put forth that geothermal reservoir is recharged with the ice masses located at an altitude of 6458 m above mean sea level (msl) in the west of Puga valley, probably from the highest peak of Polokong La mountain. The two key processes participating in regulation of proportions of the dissolved salts in the thermal waters are silicate weathering and ion-exchange kinetics. The powder X-ray diffraction study reveals a major occurrence of hydrothermal mineral thenardite in the hot spring deposits for the first time along with huge encrustations of trona, borax, calcite and elemental sulfur. The high-temperature fluids encounter thenardite, pyrite, and jarosite-bearing minerals in basement rock causing enrichment of SO42− and Cl− in geothermal waters. The temperature-dependent speciation modelling (50 °C–200 °C) for major ion Na+ reveals the composition of the reservoir fluid (~150 °C): Na+ > NaCO3− > NaSO4− > NaHCO3 > NaF > NaOH. A conceptual evolution model of thermal waters involving the recharge-deep circulation-mixing-discharge of thermal springs is hence put forth in the study using various hydrogeochemical insights.

Age-dependent potential health risk assessment due to radioactive radon-222 in the environs of highly populated Durgapur industrial zone and nearby Bakreswar hot spring, India.

It is well known that exposure to a high concentration of radon-222 causes severe health effects, including cancer. The present article includes a survey on radon-222 in the water bodies of the city Durgapur [non-geothermal area] and nearby Bakreswar hot spring [geothermal province], India. The possible sources of radon from natural radionuclides and industries have been discussed in the article. Durgapur is a densely populated [~ 3680 persons/km2] industrial city with a population of 0.57 million. On the other hand, many tourists and pilgrims usually visit Bakreswar throughout the year. Age-dependent potential health risk assessments of the dwellers at Durgapur and Bakreswar due to radon exposure were performed for the first time. The present work is the first attempt to estimate the mean ingestion /and inhalation dose per annum, total effective dose [TED] per annum and the health risk assessment for cancer in adults, children and infants due to radon exposure at Durgapur and Bakreswar. In some cases, the values of TED exceed the permissible limit of 100 micro Sievert per year [µSv/y] as recommended by EUC and WHO. The radiation profile maps relating to radon concentration and associated contour maps of health risk factors [HRF] for the adults, children and infants were also prepared for the first time. Some areas were identified as high-risk zones, and the dwellers are prone to a high risk of cancer. The article also proposed several techniques to reduce radon in water and buildings. The authors also recommended banning some water sources to protect people from radon risk. This study will help scientists, policymakers, industrialists, farmers, government agencies and public health departments.

Magnetotelluric investigations over geothermal provinces of India: an overview

Magnetotelluric (MT) and audio-magnetotelluric (AMT) studies are sensitive to the geothermal fluids filling the faults and/ or fracture zones of the geothermal system. In India, MT/AMT studies have been carried out in NW Himalayas, central, eastern, and western India. In other areas, detailed MT/AMT studies need to be expedited. This review paper presents the art of geothermal exploration in India by using MT/AMT techniques and identifies potential zones that can be exploited for power generation and direct application. Reservoir characteristics, carbon emissions reduction methods, and levelised cost factor are also discussed.

Re-visiting Geothermal Fluid Circulation, Reservoir Depth and Temperature of Geothermal Springs of India

• Most of the thermal water are of immature water type. • Four major water types were identified in four major geothermal provinces. • For the Himalayan springs, water–rock interaction are dominant at depths. • The reservoir temperature of the Himalayan and the west coast springs are higher. • The fluid circulation depth for the Himalayas are deeper (∼2.14 km). Stringent pollution control regulations and sustainable development goals have renewed the interest in finding an alternate, renewable, and sustainable energy resource. Geothermal energy is one such potential source, which needs to be explored. This study deals with the geochemical characteristics and reservoir parameters of the major hot springs located in four diverse terrains in India, as well as their energy potential in terms of reservoir temperature. The west coast springs have mostly Na-Cl, Ca-SO 4 , and Na-HCO 3 water types, and are likely to be influenced by seawater intrusion through deep penetrating faults and fractures, whereas the Odisha hot springs show immature water of Na-Cl, Ca-HCO 3 types. The West Bengal springs show Na-Cl-HCO 3 water type, presumably derived from dissolution of albite at higher temperatures at depths (∼1.13 km). The Himalayan springs water are mostly of NaHCO 3 , CaHCO 3 , NaCl, and CaSO 4 types, and are geochemically more diversified compared to the west coast, West Bengal, and Odisha hot springs. The estimated reservoir temperatures and reservoir depths are 150 ± 10 °C, and 2.11 ± 0.2 km; 120 ± 5 °C, and 1.71 ± 0.17 km; 100 ± 5 °C and 1.13 ± 0.13 km; 110 ± 5 °C and 1.37 ± 0.32 km for the Himalayan, west coast, West Bengal and the Odisha geothermal systems, respectively.

Genesis, evolution, speciation and fluid-mineral equilibrium study of an unexplored geothermal area in Northeast Himalaya, India

Arunachal Pradesh geothermal area, located in the Northeast Himalayan geothermal province is an unexplored geothermal area in India due to its rugged terrain and inaccessibility. In this study, a detailed geochemical characterization of the thermal waters is carried out to elucidate the source of the dissolved constituents and also to determine the subsurface reservoir temperature. The thermal waters are found to be nearly neutral to slightly alkaline (pH = 7.15 to 8.40) having highly variable EC values (EC ranges from 204 to 3600 µS/cm). Most of the thermal waters are mixed cation (Na, Ca)-HCO3-SO4 type whereas a few of them are of Na-HCO3 type. Silicate weathering and ion-exchange processes are found to be the two important mechanisms controlling the concentrations of the dissolved solutes in the thermal waters. The temperature dependant (20 to 198 °C) speciation analysis of the major ions (Na, K, Ca and Mg) shows that the composition of the reservoir fluid is dominated by free Na+ ions followed by K+, Ca2+ and Mg2+. The sulphate complex is found to be majorly dominated by both CaSO4 and MgSO4 whereas carbonate is mainly controlled by CaCO3 and CaHCO3+ species. Environmental stable isotope (δ18O, δ2H) data confirms the meteoric origin of these thermal waters. The isotope composition of the thermal waters in this region is found to be depleted compared to the non-thermal water samples indicating a high altitude precipitational recharge for these thermal waters. The altitude of the recharge estimated from the δ18O-altitude plot reveals that the precipitation occurring at the Gorichen Peak (altitude of 6858 m), the highest peak of the Arunachal Pradesh, is the main source of recharge for these thermal waters. Of different silica geothermometers, the quartz geothermometer gives the most conservative estimate (71 to 133 °C) of subsurface reservoir temperature. The quartz geothermometer gives a lower estimate of reservoir temperature due to mixing with non-thermal water. However multicomponent geothermometrical modelling results give a tightly constrained subsurface temperature i.e. 160±2 °C which may be taken as the probable reservoir temperature in this unexplored geothermal region. The study highlights the potential of integrated isotope-geochemical studies in expanding the geothermal energy utilization in India.

The potential to improve air quality by increasing the use of deep geothermal energy

Increasing the use of geothermal energy may be one of the tools bringing us closer to achieving the European Commission’s objective of reducing greenhouse gas emissions by 55% by 2030. Air quality improvement plays a strategic role in achieving sustainable energy development. Both European and national legislation in this field is particularly comprehensive and effective, establishing rules for monitoring and preventing air pollution in order to avoid adverse effects on human health and the environment. Unfortunately, the effective air pollutions monitoring network currently in place in Poland, with 156 monitoring stations, mainly concerns agglomerations and cities with over 100,000 inhabitants. The lack of information on the state of pollution in smaller towns is a significant limitation in terms of research aimed at assessing the effects of corrective measures taken, such as the possible transformation of district heating systems based on RES, including the use of deep geothermal energy. This paper proposes some solutions which allow the effective estimation of air conditions in locations not covered by environmental monitoring, in the context of the potential to develop geothermal resources in the rich geothermal province of Central Poland.

Interpretation of gravity\u2013magnetic anomalies to delineate subsurface configuration beneath east geothermal province along the Mahanadi rift basin: a case study of non-volcanic hot springs

Gravity and magnetic studies have been carried out over a non-volcanic hot spring zone consisting of Atri and Tarabalo hot springs along the intracontinental Mahanadi rift basin to delineate the subsurface structures and to understand their effect on the geothermal activities over a stable continental region. Calculated gravity and magnetic anomaly maps unveil the presence of hot springs along Mahanadi fault. The four-layer subsurface configuration as observed using radially averaged power spectrum analysis and 3D Euler solutions of both gravity and magnetic data indicates occurrence of multi-phases sedimentation and tectonic events. 2D forward, 2D inverse, and 3D inverse residual gravity models have delineated high-density igneous intrusive bodies surrounded by comparatively less dense Khondalites and Charnockites rich altered zones. The sharp high to low density transition zones are identified as the regional Mahanadi fault. The India–Antarctica rifting, existence of two hot springs along the Mahanadi fault of the rifted basin, and similarity in water chemistry strongly indicates an interconnection between these two hot springs. Igneous intrusions and radiogenic element-rich metamorphosed shallow formations combinedly acting as the heat source. Deciphered altered zone, deeper intrusion and deeply connected regional fault along the hot springs confirmed that this regional fault is providing the major pathway for water circulation through radioactive element-rich altered zones while the local and shallow fractures connecting the Mahanadi fault feed the hot springs of the study area.

Geochemical characterization of geothermal spring waters occurring in southern part of Gujarat and West Coast Geothermal Province of Maharashtra, India

Geochemical characterization of geothermal spring waters occurring in southern part of Gujarat and West Coast Geothermal Province of Maharashtra, India

Hydrogeothermal potential assessment in a complex tectonic environment by geophysical and hydrogeochemical tools: a case of the geothermal province of Hajeb Layoun-Jilma-Oued Hjal basins (Central Tunisia)

Hydrogeothermal potential assessment in a complex tectonic environment by geophysical and hydrogeochemical tools: a case of the geothermal province of Hajeb Layoun-Jilma-Oued Hjal basins (Central Tunisia)

Constraining the mean transit time (MTT) of relatively modern thermal waters in Deccan volcanic geothermal area, India using tritium tracer

Constraining the mean transit time (MTT) of thermal waters is essential to understand the sustainability and renewal rate of geothermal systems. In this study, tritium concentrations of samples from five thermal water manifestations, three shallow groundwater wells (dug wells) and one deep groundwater (borehole) are analysed at regular time intervals for three years to estimate the MTT of the thermal and non-thermal waters in the Deccan Volcanic geothermal province by using lumped parameter models. The tritium concentrations of the thermal waters are found to vary between 0.77 and 2.77 TU (±0.0.23 TU at 1σ) which are lower than those of the shallow non-thermal groundwater (5.4–7.18 TU) (±0.40 TU at 1σ) whereas the tritium value for the deep groundwater ranges between 2.30 and 2.78 TU (±0.27 TU at 1σ). Among different lumped parameter models, PFM (piston flow model), EMM (exponential mixing model) and EPM (exponential piston flow model) are used to estimate the MTT of the groundwater and thermal waters in the study area. The historical records of weighted mean concentration of tritium in precipitation at the nearby Tural-Rajwadi geothermal area is taken as input function in the modelling procedure. The PFM and EMM models represent the lower and upper case of the EPM model mixing, respectively whereas the values obtained from the EPM models provide the actual range of mean transit times. The overall uncertainty in the MTT estimation has also been computed. The MTT of the younger fraction of the thermal waters in Ganeshpuri thermal water (HS-1) and Akloli thermal water (HS-7) are found to be 70 ± 5 and 90 ± 14 years old respectively. The MTT of both the shallow groundwater (DW-1 and DW-3) samples is estimated to be ~1.5 years whereas the MTT of the deep groundwater (BH-1) is 39 ± 6 years. Thermal springs in this area undergo mixing with non-thermal water during its ascent towards the surface as a result binary mixing model has been applied to find the MTT of the mixed thermal spring. The aggregate MTT of HS-1 turns out to be 7860 ± 870 years. This study of MTT estimation can be used for accessing the sustainability and renewability of these thermal waters compared to other thermal areas in Deccan volcanic region.

Sustainable management to prevent seismic risks in the Büyük Menderes geothermal province (SW Turkey)

Sustainable management to prevent seismic risks in the Büyük Menderes geothermal province (SW Turkey)

Heat Transfer Through the Wairakei‐Tauhara Geothermal System Quantified by Multi‐Channel Data Modeling

AbstractTo obtain the fullest picture of geothermal systems, it is necessary to integrate different types of data, for example, surface electromagnetic surveys, lithology, geochemistry, and temperature logs. Here, by joint modeling a multichannel data set we quantify the spatial distribution of heat transfer through the hydrothermally altered, impermeable smectite layer that has developed atop the Wairakei‐Tauhara system, New Zealand. Our approach involves first constraining magnetotelluric inversion models with methylene blue analysis (an indicator of conductive clay) and mapping these onto temperature and lithology data from geothermal wells. Then, one‐dimensional models are fitted to the temperature data to estimate heat flux variations across the field. As a result, we have been able to map the primary seal that insulates the geothermal reservoir and estimate the heat flow of the system. The approach could be applied in geothermal provinces around the world with implications for sustainable resource management and our understanding of these magmatic systems.