Geothermal Reservoir Research Articles

The Evolving Landscape of Oil and Gas Chemicals: Convergence of Artificial Intelligence and Chemical-Enhanced Oil Recovery in the Energy Transition Toward Sustainable Energy Systems and Net-Zero Emissions

Chemical-enhanced oil recovery (EOR) is a field of study that can gain significantly from artificial intelligence (AI), addressing uncertainties such as mobility control, interfacial tension reduction, wettability alteration, and emulsifications. The primary objective of this paper is to introduce an integrated framework for AI and chemical EOR for energy harvest operations. Central emphasis is placed on the energy transition, with the aim of expediting the development of cleaner energy harvesting systems and attaining the goal of net-zero emission. To do so, we present how the energy transition is changing the manufacturing of the chemicals for EOR application. For this, the uncertainty associated with materials' design and critical role of the simulators for transferring the laboratory experiences into full-field implementations is discussed. The concept of digitalization and its impact on energy companies are highlighted. The role of digital twin in simulators integration is discussed, emphasizing how increased data access can help design more tolerant chemicals for harsh reservoir environments using real-time data. Also, we discuss how the chemical suppliers, research institutes, startups, and field operators can benefit from self-leaning and robotic laboratories for chemicals manufacturing. Moreover, this paper explores how including AI perspectives can improve our understanding of developing chemical formulations by blending hybrid capabilities. This approach contributes to making energy production more sustainable and aligning with the goal of zero emissions. A workflow is presented to demonstrate how the integration of AI and chemical EOR can be used for both hydrocarbon production and other energy transition operations, such as carbon capture, utilization and storage, hydrogen storage, and geothermal reservoirs. The outcome of this paper stands as a pioneering effort that uniquely addresses these challenges for both academia and the industry and can open many additional doors and identify topics requiring further investigations.

Geothermal reservoir characteristics of SYYD-1 well and energy efficiency analysis after geothermal transformation

SYYD-1 Well in Daqing, a shale oil parameter well, was implemented by the Shenyang Geological Survey Center of the China Geological Survey in 2019. The drilling depth and diameter are 2484.0 m and 139.7 mm, respectively. To satisfy the local demand for clean energy, cable transmission spiral perforation technology was applied to transform this well into a geothermal well. Based on a comprehensive understanding of the regional geothermal conditions, the geothermal reservoir characteristics of SYYD-1 Well were investigated through a detailed geophysical interpretation. Crucial energy efficiency parameters, such as the theoretical recoverable and annual available geothermal energies, were calculated using analytical methods after the transformation of the well. Subsequently, geothermal fluid quality and combustible gas composition were analyzed to provide technical guidance for the development and use of local clean energy. The results showed that the geothermal resource in SYYD-1 Wellis mid-deep hot groundwater. The primary geothermal reservoir consists of the sandstone strata of the second and third members of the Qingshankou and Quantou Formations, whereas the caprock is an extremely thick mudstone stratum of the Cretaceous Sifangtai, Nenjiang, and Yaojia Formations. The depths of the top and bottom of the geothermal reservoir are 1281.6 and 2464.4 m, respectively, where the temperatures were 44.08 and 84.20 °C, respectively; the average temperature was 64.14 °C. The wellhead water temperature remained stable at 44.0∼50.0 °C. The pH, total dissolved solids (TDS), and total hardness of the geothermal fluid were 8.29, 5536.0 mg/L, and 38.2 mg/L, respectively. This water could be classified as highly mineralized, alkaline, extremely soft water, of the hydrochemical Cl·HCO3-Na type. Methane was the main combustible gas in the wells, accounting for 97.8% of the total gas. The exploitable water quantity, theoretical recoverable geothermal energy, and annual available geothermal energy of the well were 163.68 m3/d, 362.07 KW, and 6.85 × 106 MJ, respectively. The geothermal resources of the well could be used for physiotherapy, bathing, and heating. The geothermal gradient of reservoir (1319.0∼2464.4 m) is 2.8 °C/100 m, which is suitable for development. The concentrations of Br−, I−, and F− in the geothermal fluid meet the requirements in the standard for natural medical value; substantial social, environmental, and economic benefits can be gained after the safe treatment of combustible wellhead gas and operational implementation.

Geothermal reservoirs: From vapour dominated to conductive systems

Geothermal reservoirs are part of the system needed to produce electricity using geothermal fluids. The temperatures in the reservoirs are important for choosing the type of plant. It is also important to know the principal type and amount of fluid that the reservoir can provide. Temperature and pressure in the reservoir will determine whether the fluid is liquid or vapour and whether the system is predominantly conductive or convective. In this work we describe the different types of systems, from the vapour systems where the observed temperatures are highest, up to systems used with geothermal heat pumps that exploit differences in temperature between the soil and the atmosphere. In the last part of the work we present a low-enthalpy geothermal reservoir, located near an old building of the Évora University at Alentejo, in the South of Portugal, that is used to climatize the rooms located in the cloisters of the building. We present the device and some problems related to the exploitation of this reservoir.

Laboratory evaluation of high-temperature resistant lysine-based polymer Gel systems for leakage control

In-situ crosslinking gel known for its cost-effectiveness, has been employed for decades to plug high-permeability features in subsurface environments. However, some commonly used crosslinkers are being phased out due to the increasingly rigorous environmental regulations. As a newly discovered environmentally friendly crosslinker, lysine can crosslink the partially hydrolyzed polyacrylamide through transamidation reaction. The present work aimed to study the effect of polymer composition and concentration on the gelation behavior of lysine and high molecular weight acrylamide-based polymers. Several commercial high molecular weight polymers with different contents of 2-Acrylamido-2-methyl-1-propane sulfonic acid (AMPS) including AN-105/125, SAV-55/37/28, and SAV-10 were deployed in this work. High-temperature/pressure-resistant glass tubes were used to study the crosslinking behavior. The plugging efficiency test used a high permeability sandstone core (1600 mD). Besides, the effect of salinity and pH on the crosslinking behavior, gel strength, and long-term thermal stability was also studied. Results showed that increasing the AMPS content could prolong the gelation time, but the polymer and lysine mixture failed to form gels when the AMPS content was excessively high. Additionally, increasing the AMPS content negatively affects the gel strength but positively impacts long-term thermal stability. Polymer gel with a relatively high content of AMPS could be stable in 0.5 % CaCl2 solution at 130 °C for over 200 days. The polymer/lysine gel system can efficiently plug the high permeability matrix, and the plugging efficiency is higher than 99 %. The polymer/lysine gel system is a promising green leakage control system in treating the high conductivity features in geothermal and oil reservoirs.

Effects of Arrhenius kinetic on the magnetized nanofluid flow through a porous stretchable cylinder with slip conditions

ABSTRACT This research addresses the implications of slip on the magnetohydrodynamic transport properties of Newtonian nanofluids. The study employs Buongiorno’s theoretical framework and focuses its attention on a cylindrical object that experiences tensile deformation inside a medium characterized by porosity. In contrast to the often observed boundary conditions that presume a constant temperature and concentration, the current research utilizes hydrodynamic and thermal slip conditions. The recognition of many significant elements, including the Arrhenius activation energy, magnetic field, and viscous dissipation, also has important significance. The phenomena of interest pertaining to fluid flow is first defined and afterward converted into a nondimensional form by including relevant commonalities. In order to do a thorough examination of the current situation, the shooting algorithm and the bvp 4 c technique are used. Graphical and tabular representations are used to demonstrate the implications of several emerging features on the velocity, temperature, and dispersion of nanoparticles. The observed data suggests that a rise in chemical reaction parameters leads to a drop in nanoparticle concentration distributions, but the activation energy parameter exhibits an opposite tendency. It is discovered that the boundary layer thickness under slip flow circumstances differs from that seen without slip flow. The Sherwood number rises when the chemical reaction parameter gets higher, whereas the activation energy parameter escalates in the opposite direction. The present research covers a broad variety of applied sciences applications, with a special emphasis on thermal oil recovery, geothermal reservoirs, chemical engineering, and nuclear reactor cooling.

Enhancing reservoir stimulation and heat extraction performance for fractured geothermal reservoirs: Utilization of novel multilateral wells

Enhanced Geothermal System (EGS) is a promising approach to improve the production efficiency of deep geothermal energy (e.g. hot dry rock). However, it faces with significant unsolved challenges to create connected fracture networks between injection-production wells, maintain high flow rates and obtain sufficient thermal power in EGSs. To address these challenges, we propose a novel multilateral-well EGS method for improving the performance of both reservoir stimulation and heat extraction from hot dry rock. In this contribution, we construct an integrated numerical model to simulate the processes of complex fracture propagation and thermal heat production as a whole. This model fully couples fluid flow, heat transfer, rock deformation and fracture propagation, taking into account the generation of new fractures, reactivation of pre-existing fractures, and mechanical interaction between hydraulic and natural fractures. The reliability of the integrated model is well verified with the analytical solution and experimental data. Subsequently, the damage and temperature fields as well as the resulting heat extraction performance of the multilateral-well EGS and conventional vertical-well EGS are compared. The results indicate that the stimulated reservoir permeability and connectivity, extracted thermal power under the configuration of multilateral-well EGS are much higher (about an order of magnitude) than those under the scheme of vertical-well EGS. This study presents a promising alternative for EGS to achieve enhanced reservoir stimulation and heat extraction performance.

Mixed convection hybrid nanofluid flow over a stationary permeable vertical cone with thermal radiation and convective boundary condition

AbstractMany real‐world devices, such as heat exchangers, geothermal reservoirs, and cooling systems, utilize the concept of boundary layer flow across a cone geometry. The current study presents and analyses the mathematical formulation for the mixed convection flow of a hybrid nanofluid over a permeable stationary cone. The heat transfer analysis considers the effects of thermal radiation and convective boundary condition. Numerical and statistical analyses of this flow problem yield new, physically significant results. The numerical analysis is carried out using the bvp4c solver in Matlab. Similarity transformations are performed to obtain a system of nonlinear ordinary differential equations from the governing partial differential equations and boundary conditions. In both assisting and opposing flows, spherical‐ and platelet‐shaped nanoparticles are observed to produce the lowest and highest local skin friction coefficient, respectively. The spherical‐ and blade‐shaped nanoparticles also offer the highest and lowest local Nusselt number, respectively, with a difference of 6.4% (assisting) and 6.03% (opposing). Meanwhile, the increase in the mixed convection parameter raised the velocity profile but diminished the temperature profile of the hybrid nanofluid. Then, the relationship of the Biot number , suction , and thermal radiation ) parameters with the local Nusselt number is investigated through the response surface methodology (RSM). The local Nusselt number for the current flow problem is estimated to be maximized at 0.814323 (assisting) and 0.814629 (opposing) when these parameters are at the highest range of , , and . Several researchers had presented experimental studies conducted at different temperatures (15, 25, 35°C), mass flow rates (ranging from 0.00076 to 0.041 kg/s), and nanoparticle concentrations (0.387, 0.992, 3.12, 4.71 mass%).

Three-dimensional magnetotelluric and gravimetric imaging of Mount Lawu geothermal prospect area, Indonesia

Mount Lawu is a stratovolcano located on the border of Central Java and East Java Provinces in Indonesia. At least eleven manifestations indicate its geothermal potential in the form of hot water and fumaroles. This study aims to describe a geothermal system based on an integrated analysis of magnetotelluric (MT) and satellite gravity data. Some additional geochemical and petrological data analyses were also used to explain the existing hydrothermal system in this area. It is inferred from the gravity derivative analysis that fault structures exist in a location with high permeability, which acts as a controlling structure for geothermal manifestations. The 3-D resistivity inversion was carried out using MT full-impedance tensor data, while the 3-D density model was reconstructed based on the residual anomaly computed from the topography-free gravity disturbance. The 3-D resistivity model, from magnetotelluric inversion, shows a clay cap distribution, corresponds to a low resistivity anomaly, centered at the southern part of the mountain peak with a thickness of about 1 kilometer, which narrows to the western region where the hot spring shows an outflow manifestation. The gravity inversion shows several low-density bodies in the same location as the low-resistivity anomaly attributed to a clay cap. Coincident resistivity and density anomalies constrain the horizontal location of the geothermal reservoir. Despite the incapability of the model to resolve the body of the geothermal heat source, it can be inferred from the inversion results that the heat possibly emanates through the thermal conduction passage below the reservoir zone from the source located deeper down than the reconstructed models.

Experimental investigation on the effect of grain size of granitic rocks on the fracture roughness and toughness

The fracture surface characterization, such as the fracture roughness, is essential to flow and heat transport through the fracture in the geothermal, oil, and gas reservoirs stimulation by hydraulic fracturing. This research presents an experimental approach to assess the correlation between the fracture roughness and mode I fracture toughness (KIc) of the granitic rock with different grain sizes, which is crucial in geothermal reservoirs. Three types of granite with the same mineralogical compositions but fine, medium, and coarse-grained structures were selected and prepared. Fracture toughness values were measured using a novel specimen called ENDB (Edge Notched Disc Bend), in which a cracked disc shape specimen was loaded in three-point bending. The photogrammetric method was used to estimate the value and distribution of surface roughness after ENDB testing and investigate the relationship between fracture morphology and fracture toughness. Based on the experiments, a clear correlation between the roughness and fracture toughness was observed in the three investigated granite types with different grain sizes. The FPZ around the crack tip, tortuosity, intergranular, and transgranular cracks were examined to study the effect of grain size on fracture toughness and roughness precisely. The results show that by increasing the grain size, KIc and surface roughness increased. The results also showed that the roughness parameter for the three types of rocks in the direction of the crack growth path is greater than the direction perpendicular to the crack growth path.

Optimised design of downhole turbodrills with bending-torsional tilting blade

Deep dry hot rock mining drilling operations confronts several challenges including the high-temperature conditions in the downhole environment, the unreliable performance of surface drives, and the difficult drillability of geothermal reservoir rocks. As a result, the use of downhole motors in drilling operations becomes an imperative selection. The all-metal turbodrill presently stands as the sole downhole motor capable of effectively drilling in deep wells with temperatures exceeding 180°. Although it can withstand high temperature, the output torque is small. In this study, we focus on the optimised design of the turbodrill blades with the objective of enhancing the output torque, addressing the prevailing issue of limited output torque. First, the structural parameters and parametric design are determined based on turbine blade design theory. Utilizing the quintic polynomial method, a two-dimensional blade profile is generated. Subsequently, an output torque model applicable to unsteady flow conditions is derived using the moment of momentum theorem in its integral form; Utilizing the designed blade profile, the Unigraphics NX (UG) software is used to illustrate the combination of spatial twisting, bending and tilting of the blade for the combination of the modelling method, and a three-dimensional bending-torsional tilting blade was achieved. Subsequently, numerical analysis, employing Computational Fluid Dynamics (CFD) simulation software, was conducted to examine the impact of intricate spatial modelling on the blade's flow field parameters. The optimal parameters for blade spatial modelling were ascertained to be a twist lofting radius of 63 mm, a bending angle of 30°, and an inclination angle of 3°. The blade in the hydraulic efficiency is reduced by only 2.7% of the case, the output torque increased by 18.87%, improving the performance of the turbodrill, so that the turbodrill in the geothermal development drilling has a good application prospect.

Numerical modelling of an advective geothermal system in the Central Andes: Sustainable utilization through borehole heat exchangers

The utilization of low-enthalpy geothermal resources emerges as a promising solution for district heating in the Central Andes region. Focused on the Pismanta field, a representative example of the prevalent advective geothermal systems in the area, this study investigates into the intricate dynamics of the geothermal reservoir. Situated within a fault-controlled basin, the Pismanta field undergoes deep infiltration of meteoric water, leading to peak temperatures of up to 90 °C. Numerical simulations conducted at varying scales yield critical insights into the characteristics, efficient exploitation, and potential repercussions of energy extraction from the reservoir. A comprehensive approach is adopted to facilitate the optimal management of this geothermal resource and a strategic closed-loop system comprising 10 shallow interconnected borehole heat exchangers (BHE) is proposed. This recommendation takes into account the specific basin geometry and the intricate interplay of pressures within the confined geothermal reservoir. Extensive simulations over a 10-year period show the sensitivity of the system to operating flow rates. By employing the suggested configuration, it is anticipated that a maximum thermal power extraction of 1 MW can be achieved. The circulating water within the system is projected to maintain a temperature of approximately 26 °C.

Re-evaluation of a geothermal system model based on high-resolution gravity field inversion: A case study of the Maritaing geothermal field, Alor Regency, East Nusa Tenggara Province, Indonesia

The Maritaing region in East Nusa Tenggara Province, Indonesia, offers significant geothermal potential for direct power generation and use. This study aims to re-evaluate the geothermal system model in the Maritaing geothermal field using high-resolution gravity inversion. High-resolution gravimetric data were collected using satellite observations and data processing techniques, allowing a better understanding of the subsurface geological structure and density distribution of rocks associated with the geothermal reservoir. This study applied data corrections to acquire complete Bouguer anomalies, gravity gradient analysis to detect geological structures, and inversion modeling of residual gravity anomalies to predict subsurface rock density distribution. The complete Bouguer anomalies exhibit positive values ranging from 70 to 140 mGal and have a northwest–southeast orientation, indicating the existence of andesitic lava and pyroclastic volcanic rocks. Gravity gradient analysis determines the geological structures, such as faults or fractures, used as conduits to create Kura Hot Springs. The model provides useful insights into geological occurrences, such as faults, rock layers, and reservoir accumulations that support geothermal fluids. Based on the present study’s findings, we provide recommendations for developing and managing geothermal resources in the Maritaing area.

Probing fractured reservoir of enhanced geothermal systems with fuzzy-genetic inversion model: Impacts of geothermal reservoir environment

Our previous study (Zhou et al., 2023) proposed a fuzzy inference model to inverse the predominant flow area in fractured reservoirs. Yet, geothermal reservoir parameters in the direction problem model are hard to make exactly consistent with the actual parameters. This study aims to discuss the impacts of discrepancies between actual geothermal reservoir environment and simulated reservoir environment on the inversion results. An inversion model (including direction problem model, fuzzy inference model, and genetic algorithm) is established to explore the location of predominant flow area under different guess geothermal reservoir environments. The effects of running time, guess reservoir environment (temperature field, pressure field, and Hot Dry Rock property) and guess predominant fracture area property on inversion results are studied. Results show that longer running time can obtain good inversion results, and the inversion speed decreases as running time increases. In addition, the inversion model has good inversion accuracy under different guess geothermal reservoir environments. Lastly, the inversion accuracy is very poor when the guess permeability of predominant fracture area is extremely low. However, the inversion model still needs improvement in the initial stage. It cannot inverse the location of predominant flow area when the running time is less than 1×107 s.

Investigation on cracking propagation patterns in hydraulic fracturing under different vug distributions: Experimental and numerical case

Natural vugs are developed in geothermal reservoirs. Communication of natural vugs can effectively improve reservoir stimulation, but the vug distribution affects its propagation pattern. In this work, large-size samples (500 × 500 × 500 mm) made of carbonate-like materials were prepared, and a series of true triaxial hydraulic fracturing tests were carried out to investigate the influence of the vug orientation and relative orientation between vugs on the propagation pattern. Moreover, the discrete element method (DEM) was used to further elucidate the effect of vug distribution on the cracking propagation mechanism. The results obtained that the increase in the vug orientation leads to an increase in peak pressure, and the relative orientation has less effect on peak pressure. In terms of propagation pattern, at low vug orientation and relative orientation (i.e. 0°, 30°), the induced crack will penetrate or deflect through the vugs, while at 45°, the induced cracks deflect but do not interpenetrate the vugs. Accordingly, numerical simulations demonstrate that the crack deflection induced by the vug is mainly due to microcracks generated by tensile stress concentration around the vugs under the pore pressure, but the high vug orientation suppresses the tensile stress domains, accompanied with an increase in the percentage of shear cracks with vug orientation. These results may improve the understanding of vuggy carbonate reservoir stimulation.

Geothermal Solutions for Urban Energy Challenges: A Focus on CO2 Plume Geothermal Systems

The utilization of geological formations, distinguished by natural porosity and permeability and protected by low-permeability caprock, has emerged as an effective strategy for carbon dioxide (CO2) storage. This method significantly contributes to mitigating anthropogenic greenhouse gas emissions and addressing the challenges of climate change. Recent research has unveiled the potential of CO2 to enhance geothermal heat energy extraction in geothermal reservoirs by acting as a subsurface heat exchange fluid. This review paper explores the viability of CO2 in augmenting geothermal heat energy extraction, comparing it to conventional water-based geothermal systems. Special emphasis is placed on CO2 plume geothermal (CPG) systems, characterized by rapid deployment and long-term utilization of geothermal energy resources. With the overarching objective of establishing net-zero energy communities, the analysis of such systems offers a comprehensive understanding of their features, providing a fresh perspective on extracted energy within the context of energy supply in integrated, sustainable energy in built systems. Notably, these systems demonstrate efficacy in meeting the power requirements of an energy community, spanning both distinct heating and electricity needs. However, the key challenge lies in selecting suitable locations. This scientific review aims to comprehend the characteristics of CPG under specific temperature and pressure conditions while optimizing subsurface permeability. This insight is pivotal for identifying future locations for CPG operations with the intent of powering small energy communities.

Experimental study and kinetic modeling of high temperature and pressure CO2 mineralization

The potential for in-situ CO2 sequestration was analyzed experimentally for one basaltic hyaloclastite sample from the Nesjavellir geothermal reservoir in Iceland and three metasedimentary rock samples from the Kızıldere geothermal field in Turkey. Based on batch reaction experiments, this paper demonstrates the interaction between a CO2 gas-charged fluid and rock samples from these reservoirs. The experiments were conducted at 260 °C and 0.8 MPa, and 105 °C and 17 MPa for the basaltic and metasedimentary rocks, respectively. The experimental results indicate that CO2 sequestration within the glassy basaltic rocks is hampered by zeolite, chlorite, and anhydrite, which compete with carbonate minerals to uptake divalent cations at the P-T conditions applied. In contrast, the carbonation process for the metasedimentary rocks is inhibited by their mineralogical composition. Generally, these rocks are less reactive and provide an insufficient supply of divalent cations. The batch reactor experiments were numerically simulated with the PHREEQC geochemical modeling program. The simulations indicate that CO2 sequestration is feasible at the tested P-T conditions, provided that silicate and SO4 mineralization is suppressed for the basaltic rocks and that there is an effective source of divalent cations for the metasedimentary rocks.

Heat extraction performance analysis of a multilateral wells exploitation system with super-long gravity heat pipe

Super-long gravity heat pipe (SLGHP) system has previously been proven as an environmental and efficient technology in exploiting hot dry rock. This study proposed a multilateral-well SLGHP system to achieve the purposes of improving heat extraction performance and fully utilizing fractured reservoirs. The heat extraction performance was investigated by establishing a 3D thermal–hydrologic (TH) coupling model. It is found that, compared to traditional single-well SLGHP system, after 30 years of operation, multilateral-well SLGHP system has improved the heat extraction rate by 38.1 kW and increased the heat compensation by 61×1012 J. The utilization ratio of geothermal reservoirs has been improved by 8.1%. In addition, the effects of different well layouts on heat extraction performance are also studied. Injection wells at the top of fractured reservoir increase the heat extraction rate by 6.4 kW compared to placing them in the bottom area. The relative changes of wellbore location in fractured reservoirs have slight effects on heat extraction performance. This study could provide good suggestions for the SLGHP system to obtain better heat extraction performance.

A numerical investigation into the propagation of acid-etched wormholes in geothermal wells

Carbonate geothermal reservoirs are widespread in the Beijing-Tianjin-Hebei region, and acidification stands out as the most effective method to enhance the heat recovery potential of these reservoirs. To understand the propagation patterns of acidized wormholes in geothermal reservoirs, a pore-Darcy scale mathematical model of acidizing reactions in geothermal reservoirs has been established. A normal random distribution function is introduced to depict the reservoir's heterogeneity. Using the finite element method, the study simulated the impact of injection rate, acid concentration, diffusion coefficient, and acid-rock reaction rate on wormhole morphology. The findings indicate that the reaction is uniform in the early stage of acidification, becoming non-uniform in the late stage, ultimately forming distinctive wormhole structures. The acidification radius is more extensive along a particular direction post-acidification. Increasing the acid injection rate, acid concentration, and initial specific surface area proves beneficial in enhancing the acidizing effect. The outcomes of this study hold theoretical and technical significance for optimizing the thermal recovery efficiency of geothermal reservoirs.

Prospects of geothermal field development in Gandhar, Gujarat, India

Field development is an important part of natural resource utilization and exploration because it involves a systematic evaluation and optimization of a specific area. This study examines the geothermal field development in the Gandhar region of Gujarat, India. Gandhar for the past several decades has been a flourishing field for hydrocarbon extraction. However, as the world is dealing with environmental issues and the need to shift to cleaner and more sustainable energy sources, geothermal energy has emerged as a feasible and ecologically sound option. This study aims to understand the potential of regions in and around Gandhar as a prospective geothermal field of the west coast continental margin of India. Three primary disciplines namely geological, geochemical, and geophysical surveys are employed on the surface to assess the potential of Gandhar's geothermal resources. Geological assessments provide information about underlying geological formations, which might help to locate possible geothermal resources. The Deccan basement is a prominent source of magmatic heat, with a thermal gradient ranging from 1.29 to 1.87 W/K. This enhances Gandhar's geothermal potential by heating the underlying water in conjunction with radionuclides found in the Earth's core. The temperatures range from 60 to 80 °C according to Giggenbach triangle method. Gandhar's geothermal potential is further highlighted by the fact that its water is bicarbonate-rich, which connects it to possible subterranean aquifers. These results are verified by geophysical studies. Prospective geothermal reserves and four way closures can be found by as anomalies. Gravity survey reveal a doubly plunging antiform, with gravity high value of 5.4 and 5.3 mGa l respectively, which is corroborated by magnetic peaks of 58 and 56.2 nT Areas with higher conductivity are identified by resistivity studies, which also indicate possible fluid paths and geothermal reservoirs. The paper outlines a conceptual field development plan for the identified prospect. The basic infrastructure and the cost associated with it for field development is worked out. The cost of production/MWe of energy generation is also highlighted.

Numerical study for effect of injection parameters on reservoir: A case study for Lahendong, Indonesia

A single-flash cycle of thermodynamic model coupled with a reservoir of numerical model has been developed through the COMSOL Livelink module to investigate the impact of the geofluid mass flow rate and injection temperature on production temperature and net output power of the power cycle. The geothermal reservoir model was established by using a thermal–hydraulic–mechanical (THM) module in COMSOL Multiphysics. Moreover, the single-flash cycle of the thermodynamics model was constructed in MATLAB. The geothermal reservoir conditions of Lahendong, North Sulawesi, Indonesia was adopted to simulate the geothermal power plants’ actual operation. The results revealed that the variation in geofluid mass flow rate and injection temperature impacted production temperature and net output power. The production temperature considerably decreased with an increase in the geofluid mass flow rate. However, the difference in production temperature between geofluid mass flow rates of 50 kg/s and 250 kg/s at 1st and 30th years were 0.23 K and 0.41 K, respectively. The net output power differences were also 16.204 MW and 15.349 MW, respectively. Finally, increasing the injection temperature correspondingly led to an increase in production temperature and net output power, even though the increment did not exceed 1 K and 0.002 MW, respectively.