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The repetitive process of shut-in and production in geothermal wells promotes thermal stress on the wellbore components, including annular cement. A cement sheath at a relatively shallow depth undergoes the most significant stress change due to the high differential temperature between the geothermal gradient and the production fluid's temperature. Understanding the impact of cyclical thermal stresses on cement is critical for assessing the barrier integrity at a shallow depth that serves as aquifer protection. A novel large-scale setup simulating a 1.5 m-long casing-cement-casing well section was built to study the changes in cement's sealing performance of low-enthalpy geothermal wells during production. Using this setup, a cement sheath can be cured similarly to the in situ conditions, and the annular temperature can be cycled under realistic operating conditions. The change in flow rate through the cement sheath before and after cycling is quantified through leak tests. UV dye is injected at the end of the experiment to identify the location and type of damage in the cement sheath. A hydromechanically coupled finite element model was used to estimate the stress evolution in cement during the tests. The model incorporated the impact of cement hydration and strength development during curing. The numerical results were used as a guide to ensure the test design closely mimicked in situ conditions. The results show the presence of a small microannulus immediately after curing due to hydration shrinkage. Thermal cycles reduced the permeability of the microannulus. The size of the micro-annulus was observed to be sensitive to the backpressure applied to the cement sheath, indicating the need for pressure to maintain an open microannulus. Thirty-nine thermal cycles between 80 and 20 °C did not change the permeability of the cement sheath significantly. Tensile cracks in the cement sheath were not continuous and may not be a significant pathway. The new setup allows for measuring cement's effectiveness in withstanding in situ stress conditions when exposed to thermal cycles such as geothermal and CCS wells. [ABSTRACT FROM AUTHOR]

Low-enthalpy geothermal wells are considered a sustainable energy source, particularly for district heating in the Netherlands. The cement sheath in these wells experiences thermal cycles. The stability of cement recipes under such conditions is not well understood. In this work, thermal cycling experiments for intermediate- and low-temperature geothermal well cements have been conducted. The samples were cured either under ambient conditions or under realistic pressure and temperature for 7 days. The samples did not show any signs of failure after performing 10 cycles of thermal treatment between 100 °C and 18 °C. We also tested cement formulations under drying conditions. Drying shrinkage is caused by a reduction in the water content of cement, which leads to capillary forces that can damage cement. Such circumstances lead to tensile stresses causing radial cracks. Most samples exhibited cracks under low humidity conditions (drying). Fiber reinforcement, especially using short PP fibers, improved the cement's resilience to temperature and humidity changes. Such additives can improve the longevity of cement sheaths in geothermal wells. [ABSTRACT FROM AUTHOR]

There are numerous natural outflows, 3 thermal baths, 9 disused geothermal wells, and 3 private companies operating in the Seferihisar geothermal system, including a power plant generating electricity. The potential of these resources is suitable for nonelectrical use of geothermal energy, such as greenhouse heating and thermal tourism. SWOT analysis method has been used to assess the pros and cons of the geothermal resource in Seferihisar, aiding the identification of suitable applications and investments for both present and future projects. The region is rich in terms of geothermal resources and has convenient access to both public and ware transport, which are described as strengths of the resource. However, poor management and an excess of licensed geothermal fields weaken the effective consumption of the system. A huge number of projects have led to opposition from environmentalist groups. The proven technology of geothermal energy has resulted in an increase in incentives and investment consolidations with governmental support. In the light of SWOT analysis, considering SO, ST, WO, and WT strategies, the untapped geothermal resources present in the Seferihisar geothermal system, combined with the natural attractions and cultural richness of the county, will contribute significantly to non-electrical/direct uses of the geothermal energy in the near future. [ABSTRACT FROM AUTHOR]

Asal rift is an aerial rift segment resulting from the westward propagation of the Aden ridge into the Afar Depression. Geothermal manifestations such as hot springs and fumaroles, fault creep, conductivity anomaly, and high geothermal gradient were observed both at the surface and in the subsurface. Despite many scientific works conducted in Asal to understand the rifting mechanisms, the hydrothermal fluid circulation still needs to be evaluated since it is based on simplified conceptual models. To further contribute and progress toward a quantitative evaluation of fluid circulation, a 2D numerical model perpendicular to the rift axis was developed with the objective of better understanding the role of subsurface anisotropy in fluid flow and heat transfer in the Asal rift. Numerical modeling of multiphase flow and heat transfer was carried out with an equivalent porous medium intersected by fault zones having greater permeability. Horizontal anisotropic permeability and magmatic fluid release were taken into account with different simulation scenarios. The results indicate that fault zones act as recharge/discharge areas depending on their location, permeability, and number. Simulations considering horizontal anisotropic permeability allowed the reproduction of the thermal state observed in geothermal wells with the expected general pattern of fluid circulation in the Asal rift. Comparing our result with a recent study made with a 2D numerical modeling parallel to the rift axis, we suggest the presence of a saddle point where fluid flow is both to the northeast and to the southwest direction of the rift. Moreover, magmatic fluid release assumed in two simulation scenarios showed to have an impact on the hydrological behavior of fault zones and facilitate the development of super-critical flow at the center of the rift. [ABSTRACT FROM AUTHOR]

It is difficult for the commonly used Class G oil well cement to withstand the high-temperature environment of geothermal wells, and it is easy to deteriorate the mechanical properties and damage the integrity of the cement sheath. Industrial solid waste red mud can be used as supplementary cementing materials (SCMs) to improve its mechanical properties at high temperatures. In addition, compared to Class G oil well cement, high belite cement (HBC) has lower energy consumption and better mechanical properties at high temperatures. In this study, the mechanical properties of HBC as a gel material and quartz sand and red mud as SCMs were studied at high temperatures. The ratio of HBC to SCMs and the ratio of quartz sand to red mud in SCMs were optimized using the response surface method (RSM). The response surface was established using the three-level factorial design model, which fit well with the experimental data. The optimization results show that the best mass ratio of SCMs/HBC is 37.5% and that the best quality ratio of quartz sand/red mud is 9 under the curing conditions of 180 °C. However, the best mass ratio of SCMs/HBC is 49.3%, and the best quality ratio of quartz sand/red mud is 7 under 220 °C. With the addition of SCMs, the silicon-to-calcium ratio of HBC hydration products decreases, and high-temperature-stable xonotlite and tobermorite can be formed. After adding SCMs, the cement sample is denser without obvious cracks. [ABSTRACT FROM AUTHOR]

Today, due to the increase in environmental crises and the challenges facing fossil energies, it seems necessary to exploit and use renewables. Solar and geothermal energies can be integrated as a clean and promising energy production system to produce different forms of useful energy. The existing geothermal wells in Sabalan power plant provide different thermodynamic characteristics. In this regard, this paper develops the thermodynamic-conceptual design and optimization of a new energy cycle based on Sabalan geothermal wells. The considered energy process is based on two flash cycles (FCs), and two bottoming cycles (a Kalina cycle (KC) and a CO 2 -based Transcritical Rankine cycle (CTRC)). KC and CTRC can increase the level of power generation. Besides that, in the planned energy process, heat exchangers are employed in order to reduce energetic and exergetic losses to transfer thermal energy to a liquefied natural gas cycle (LNGC). LNGC can improve the electrical energy production level. Further, it can supply natural gas (NG) to consumers in the suburbs of the power plant. Additionally, a solar energy system based on parabolic trough solar collectors (PTSCs) has been embedded in order to produce a part of the thermal energy of the energy process. In order to achieve optimal results, the genetic algorithm has been applied to optimize the energetic and exergetic performance of the considered energy process. Based on the research outcomes, the total electricity output of the designed energy process is approximately equal to 26.1 MW. Energy efficiency of almost 24.9% and exergy efficiency of nearly 53.4% are calculated for the energy cycle. Furthermore, the total exergy destroyed through the energy process is approximately 29.5 MW. Under the optimization results, the rates of energy efficiency improvement and exergy destruction reduction for mode A (with NG production) are 17.9% and 3.53%, respectively. Besides, for mode B (without NG production) the rates of energy efficiency reduction and exergy efficiency improvement are 31.7% and 22.1%, respectively. Finally, it was found that, on average, almost 112 collectors are required to supply heat based on the assumption of using solar energy. [ABSTRACT FROM AUTHOR]

As a source of sustainable, renewable, and clean energy, deep geothermal systems increasingly gain importance for the energy transition. In Germany, the North Alpine Foreland Basin is the success story for hydrothermal systems. Besides successful projects in the Munich area, recent attempts to establish successfully operating geothermal wells southwards, e.g., in Geretsried, failed due to a lack of permeability of the rock mass. Subsequent research in Geretsried found that all existing discontinuities are low to non‐productive. The current project ZoKrateS, rethinking the Geretsried reservoir being a petrothermal play, bypasses these limitations by stimulating the existing fractures, and trying to keep them conductive by embedding proppants that prevent full closure. Four detached sections of the well GEN‐1ST‐A1 were subject to individual stages of stimulation. These four sections have been stimulated by placing proppants at injection pressures below the in‐situ least principal stress at no microseismic activity. After injection the communication between well and formation appeared to be increased. Although data processing is still ongoing, linear correlations between cumulative injected volume and quasi‐static pressure may be interpreted as channel flow within highly disturbed rock masses at intersections of faults. The high elasticity of these sections enables even low pressure to cause discontinuity opening below the least principal stress. [ABSTRACT FROM AUTHOR]

The objective of this study is to develop high-temperature resistant polymers for sealing geothermal wells by reinforcing inexpensive rubber with surface-treated graphite particles. We respectively treated two types of graphite particles, small-size lamellar graphite (SFG15) and graphite nanoplatelets (GNP), with a mixture of sulfuric and nitric acids. Through surface treatment, carboxylic groups are shown to be formed on graphite surfaces, and their oxygen contents are considerable. Polymer nanocomposites were made by compounding treated graphite particles with ethylene propylene diene monomer (EPDM). Uniform dispersion of treated graphite within developed polymer nanocomposites was achieved. Direct heating of prepared EPDM nanocomposites shows that treated SFG15 and GNP both enhance the temperature resistance of EPDM by over 80 °C. Also, the addition of treated graphite to EPDM remarkably enhances its storage modulus. Among all additive types and concentrations, 3.0 wt% of treated SFG15 performs the best in enhancing the storage modulus (by up to 215.83%) and reducing tan δ , namely the loss factor. Adding treated graphite significantly enhances the specific heat capacity of EPDM and remarkably increases the heat energy required to melt it. The onset degradation temperature of EPDM-SFG15 nanocomposites is 30 °C higher than that of plain EPDM. With these enhanced thermal and mechanical properties, the prepared nanocomposites are a promising candidate for the constituent polymer of seals applicable in geothermal wells. [ABSTRACT FROM AUTHOR]

This paper reports a comprehensive survey of well drilling time and cost. The models include both specific correlations on various well types and generalised correlations for rough estimation. The models are derived from robust multivariable regression to minimise the residuals. Africa has the highest construction cost component in well drilling and the United States has the lowest. Data in various regions are compared with European and World average drilling data. Drilling time in Italy is similar to Europe and world averages. The proposed model directly estimates both the drilling cost and time to be used in fundamental research and feasibility studies for geothermal power plants applicable worldwide. [ABSTRACT FROM AUTHOR]

To 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. Plain Language Summary: In this study, we present a joint modeling study of a rift‐hosted geothermal field with the goal of quantifying first‐order components of the hydrothermal system: the smectite clay cap, temperature distribution, and heat flux. Our modeling integrates electromagnetic, lithological, and temperature data using 1D models and a stochastic framework that allows uncertainty quantification. A multichannel approach helps avoid misinterpretation with single data streams. This study is significant because it quantifies key heat flows within a complex magmatic‐volcanic‐hydrothermal province. From a practical perspective, this work can help geothermal resource decision makers decide where to drill new wells or develop better models to optimize sustainable electricity generation. Key Points: Bayesian joint inversion of magnetotelluric and clay content data to infer the clay cap boundaryModeling of inferred clay cap and well temperature data to estimate clay formation temperatures and avoid misinterpretation of conductor natureModeling of well temperature data to inferred thermal gradients and heat fluxes through the geothermal system [ABSTRACT FROM AUTHOR]

This study investigates the geochemical characteristics and implications of soil gas and geothermal fluids in the fault zone of Xiongan New Area (XNA). Spatial distribution analysis reveals high soil gas concentrations along the fault zone, prompting the establishment of measurement lines along specific fault segments, such as Niudong fault, with a vertical burial trend. The measured average Rn flux ranges from 71.44 to 335.35 mBq m−2s−1, while CO 2 flux ranges from 25.96 to 78.23 g m−2d−1. Furthermore, the average Rn and CO 2 concentration intensities range from 0.91 to 2.30 and 1.13 to 2.61, respectively, indicating significant degassing in the fault zone. Geothermal well samples are collected from the deep reservoir in XNA, displaying a predominance of Cl–Na composition. Analysis of the Na–K–Mg equilibrium diagram suggests that the chemical characteristics of deep geothermal water are a result of interactions with rocks and mixing with shallow cold water in XNA. Isotopic analysis indicates the atmospheric precipitation origin of the deep geothermal water with extensive lateral recharge from underground runoff, emphasizing strong water-rock interactions. Comparison with other tectonic units in the region reveals that the Niudong Fault Zone serves as a regional geothermal control structure, facilitating deep fluid convection. In the eastern part of XNA, the geochemical analysis reveals concentrated degassing and a relatively high proportion of mantle-derived sources near the Niudong Fault Zone. This observation suggests the fault zone serves as a primary conduit for deep gases and geothermal fluids. The findings of this research provide valuable scientific references for future urban planning, energy utilization, and geologic hazard monitoring in XNA. Continued monitoring efforts are crucial for understanding the nature of fault activity and resource distribution in the region. • The fault zone of Xiongan New Area exhibits significant degassing, with concentrations of Rn and CO 2 in soil gas showing wide ranges and being most concentrated along buried faults. • Geothermal water in XNA has a Cl–Na composition and exhibits slow runoff characteristics, with an atmospheric precipitation origin and extensive lateral recharge from underground runoff. • The Niudong Fault Zone serves as a regional geothermal control structure, facilitating deep fluid convection and potentially inducing changes in permeability leading to fault movements and earthquakes. • The high values of gas concentration intensity and flux in the RCF in the western part of XNA may be attributed to the intersection of the RCF and the XDF. • The geochemical characteristics of geothermal fluid in XNA can provide valuable insights into the geological processes and fluid dynamics within geothermal systems. The distribution of the geothermal field in XNA is indeed influenced by fault activity. [ABSTRACT FROM AUTHOR]

The study presented in this paper examines the operation of an integrated system. The study aims to present a method for utilizing geothermal energy in a way that minimizes energy waste and delivers maximum efficiency. A high-temperature geothermal well with a temperature of 300 °C is used as its primary source of energy. The system produces space heating, space cooling, electric power, hot water, freshwater and hydrogen as its outputs. These outputs utilize the excess energy that is obtained from the geothermal well, and by doing so, reduces waste, and increases the overall efficiency of the system. Among these outputs, freshwater and hydrogen are considered the most valuable, as water is an essential life resource and hydrogen is a prized form of energy. The novelty of this system compared to other geothermal sources is that it does not rely on any other source of input energy. It produces both freshwater, hydrogen and considerable amounts of electric power for commercial, industrial and/or residential use. Electric power is produced by two power cycles; the first one is a double flash steam cycle in the geothermal system and the second one is an organic Rankine cycle. 40% of the total electric power produced is sent to an electrolyzer to produce hydrogen gas. Freshwater is produced by single flash desalination. The system produces 22.1 MW of power as net electricity output. The system is assessed energetically and exergetically; it is found that the energy efficiency is 49.1%, while the exergy efficiency is 67.9%. Further parametric studies are carried out using Engineering Equation Solver (EES) to investigate the influence of operating conditions on the energy and exergy of the system. Moreover, major exergy destruction areas in the system are also identified. • A geothermal based system for producing multiple outputs is suggested. • Energetic and exergetic performance of each sub-system is investigated. • The effects of changing operating conditions on outputs are observed. [ABSTRACT FROM AUTHOR]

Geothermal resources offer a stable low‐carbon energy source. However, geothermal sites can collocate with the hypocenters of large‐magnitude seismic events. Large seismic events pose a risk to public safety and are therefore a liability for efforts to develop geothermal resources. Here, we propose "fracture caging" to limit induced seismic event magnitudes and present evidence from numerical model predictions, laboratory experiments, and field observations. Fracture caging involves drilling tactical production wells around a geothermal injection zone to contain fluids in fracture‐dominated flow systems. Prior to our work, the effect of small wells on the growth of large fractures and on flow through fractures was subject to debate. Our work shows that production wells can impede fracture growth and contain high‐pressure fluids in fracture‐dominated rocks. This containment offers a mechanism to limit induced seismicity. Plain Language Summary: Below the ground's surface, fluid can lubricate rocks which enables them to more easily slip and generate earthquakes. This is a problem for developing geothermal energy resources that require long‐term injection of water. If water could be injected without risk of earthquakes, geothermal energy production could be expanded to supply more than 60 GW of electricity in the United States alone. To confront the earthquake risk, we propose that tactical arrangements of production wells around geothermal injection wells can be used to prevent large seismic events. We refer to this arrangement as "fracture caging" because it contains injected fluid in a limited volume of fractured rock in order to prevent uncontrolled stimulation of the larger fractures that generate earthquakes. Prior to this work, we incorrectly assumed that small wells (e.g., 0.3 m diameter) could not inhibit the growth of large fractures (e.g., greater than 100 m diameter). We also incorrectly assumed that these wells could not contain fluids in the dynamic and uncertain fracture networks that are common in natural rocks. However, our models, experiments, and field data now show that fracture caging can work to contain injected fluids and thereby also limit induced seismicity, even in complex natural rock. Key Points: A production well cage can enable high‐pressure fluid‐injection simultaneously with closed‐loop flow‐containment in fractured rockModel, laboratory, and field evidence indicate that fracture caging can reduce induced seismic magnitudes despite natural complexityA cage of production wells improves subsurface flow control and adaptability to transient and dynamic fracture networks [ABSTRACT FROM AUTHOR]

We describe the design and implementation of a traffic light system (TLS) created for the stimulation phase of a 6.1-km-deep geothermal well in the Helsinki area, Finland. Because of the lack of local seismic data to calibrate the TLS, the TLS thresholds have been proposed on the basis of two parameters: acceptable ground motion levels and probabilities to reach these levels, which were then used to establish TLS magnitudes. A peak ground velocity (PGV) of 1 mm/s associated with a ML ≥ 1 event, or a ML ≥ 1.2 event alone, triggered an Amber alert. A PGV of 7.5 mm/s associated with a ML ≥ 2.1 event triggered a Red alert, where ML was a local "Helsinki" magnitude. Specific thresholds based on PGV and peak ground acceleration were gathered for critical infrastructure sites and related to earthquake magnitudes in a probabilistic way. The implementation of the TLS during the stimulation showed that the selected thresholds were reasonably conservative. Some of the Amber events were reportedly felt or heard, but the public opinion remained very favourable to the project. Measured ground motions were too low to have any impact on the built environment and the stimulation was able to proceed without being impaired by the occurrence of a Red event. Seismic data acquired during the stimulation and lessons learnt are presented and used to revisit the TLS thresholds for potential future stimulations. [ABSTRACT FROM AUTHOR]

Development of an accurate reservoir model and prediction of reservoir behaviour associated with geothermal exploitation using that model are fundamentally important for sustainable geothermal utilisation. Gravity observation for a few tens of days after a field-wide shut-in of geothermal wells potentially provides valuable constraints to improve reservoir models. We investigated the applicability of superconducting gravimeters (SGs) to short-term observations after shut-ins, as a first step towards the development of a method for reservoir model improvement using short-term gravity data. Results from a reservoir simulation of a shut-in at a geothermal field in Japan showed that gravity change at 20 days after the shut-in was 10 nm/s2. To detect such changes with SGs, locations of SG stations should be chosen to minimise noise sufficient to resolve the signal. Considering that field operations and traffic in geothermal fields can make SG data noisy, laboratory gravity measurements were carried out with a SG to investigate the influence of noise level on signal detection. Test masses, which produced a gravity change (7.7–9.0 nm/s2) comparable to the simulation result, were repeatedly placed and removed above the SG during both day and night times with different ambient noise levels. Test results showed that noise level greatly affected signal detection. The signal was only detected twice, under low-noise conditions with the standard deviations of 1.1 and 5.3 nm/s2. In addition, tests in which the SG was operated without a cryogenic refrigerator revealed that the absence of the refrigerator did not increase the noise level. Enhancing the portability of a SG by reducing its weight can make multi-location noise surveys feasible. Our method, of combining reservoir simulations and preliminary noise surveys, would enable successful SG observations to be made in relatively short periods after shut-ins, which would possibly contribute to the development of a method to obtain additional constraints to be used for reservoir model calibration. [ABSTRACT FROM AUTHOR]

This paper deals with the design, acquisition and processing of vertical seismic profiling data collected in 2016 at the directional Thônex‐01 geothermal well, drilled in 1993 in the Geneva Canton (Switzerland). The aim of the study was to obtain additional information from existing‐abandoned well for downhole geophysical characterization of potential geothermal reservoirs in the Geneva area. The main results obtained by this study allowed an improved subsurface image by multi‐offset acquisitions near and around the deviated well. Specifically we were able to (1) improve the velocity model of the Geneva Basin, which, at present, is only constrained by one unique deep exploration well, located at the south‐west of the basin, far away from the study area; (2) image the transition between the Tertiary Molasse siliciclastic sediments and the Mesozoic carbonates; (3) define an acquisition strategy for future vertical seismic profiling surveys in support of the geothermal exploration campaigns in the area. This study has demonstrated the value of vertical seismic profiling method for the refinement of the subsurface geology at local scale, and its usefulness to assist the planning of second well associated with geothermal doublets. [ABSTRACT FROM AUTHOR]

Summary: In this study, parabolic trough collector with an integrated source of geothermal water is used with regenerative Rankine cycle with an open feedwater heater, an electrolyzer, and an absorption cooling system. The absorption fluids used in the solar collectors were Al2O3‐ and Fe2O3‐based nanofluids. Detailed energetic and exergetic analyses are done for the whole system including all the components. A comparative analysis of both the used working fluids is done and plotted against their different results. The parameters that are varied to change the output of the system are ambient temperature, solar irradiance, the percentage of nanofluids, the mass flow rate of the geothermal well, the temperature gradient of the geothermal well that had an effect on the net power produced, and the outlet temperature of the solar collector overall energetic and exergetic efficiencies. Other useful outputs by this domestic integrated multigeneration system are the heating of domestic water, space heating (maintaining the temperature at 40°C‐50°C), and desalination of seawater (flash distillation). The hydrogen production rate for both the fluids diverges with each other, both producing average from 0.00490 to 0.0567 g/s. [ABSTRACT FROM AUTHOR]

• A new binary geothermal energy production system for the synthesis of green methanol with electricity and freshwater is developed. • The system is modeled and analyzed in depth by using thermodynamic methods. • Energy and exergy efficiencies are evaluated as 36.96% and 39.31%, respectively. The development of an integrated binary geothermal energy production system for the synthesis of green methanol with electricity and freshwater is achieved in this study along with its thermodynamic analysis and assessment through the applications of energy and exergy methodologies. Further to being among the most promising solutions for the future, clean energy sources provide a wide range of energy carriers that may be utilized by communities as well as individuals. Among these energy carriers, hydrogen has attracted considerable attention as a realistic long-term carbon-free energy route. Moreover, methanol and ethanol are proposed as alternative energy carriers synthesized by clean hydrogen. In this regard, the developed system includes a double flash binary geothermal system, an organic Rankine cycle, a multi-effect desalination system, an alkaline electrolyzer, and a methanol synthesis system. In this system, an alkaline electrolyzer is utilized to perform hydrogen production, and then the produced hydrogen is employed for green (clean) methanol production. The performance-related parameters for the overall system and its subsystems are all thermodynamically evaluated with the Engineering Equation Solver software. The developed system utilizes geothermal energy as a renewable energy source and results confirm that the developed system produces a capacity of 0.019 kg/s of green methanol. The parametric studies are further performed to demonstrate the effects of various first flashing pressures on the qualities of steam, mass flow rates of high pressure turbine, and energy and exergy efficiencies. Moreover, the effects of geothermal well temperature on energy and exergy efficiencies are considered. The effects of electrolyzer power usage and general efficiency on the methanol production rate are also examined. The overall energy and exergy efficiencies of the system are determined as 36.96% and 39.31%, respectively. [ABSTRACT FROM AUTHOR]

• Kozaklı shallow cold spring waters are mostly of Ca-Na-HCO 3 and Ca-Mg-HCO 3 type, whereas deep geothermal fluid are Na-Ca-Cl-SO 4 type. • The δ18O and δ2H values of thermal waters indicate their deep-circulating and high-altitude meteoric origin. • REY anomalies are inheritance from geologic host materials and/or fractionation of these elements during water-rock interactions. • Kozaklı is suitable for geothermal system and geothermal potential reaches its maximum level at the intersections of volcanism and tectonism. Kozaklı is one of the most important areas of Central Anatolia in terms of geothermal potential and it is characterized by thrust and normal faults. These faults, accommodating deep circulation of hydrothermal fluids of meteoric origin, are the primary controls of the geothermal systems in this region. Chemical and isotopic composition of the hot springs and geothermal fluids was monitored throughout 2017. The surface temperature of the fluid ranges from 24.9 to 96 °C. The cold spring waters are mostly of the Ca-Mg−HCO 3 type in the study area. Major element chemistry of the water reveals that the deep geothermal fluids are mostly of the Na-Ca-Cl-SO 4 type while the shallow geothermal well waters are Ca-Na−HCO 3 waters. Silica geothermometers suggest that the reservoir temperature ranges from 103 to 173 °C. Based on the δ 18O– δ D relationship, water samples have a high-altitude meteoric origin. Stable isotopic data indicate that the geothermal fluids are formed by local recharge and deep circulation of meteoric waters. The Rare Earth Elements and Yttrium (REY) composition showed that Eu, Ce and Y anomalies are related both to inheritance from geological host materials and the fractionation of these elements during water-rock interactions. [ABSTRACT FROM AUTHOR]

Highlights • Supercritical fluids form around magmatic intrusions from conductive heating of surrounding subcritical geothermal fluids. • Supercritical fluid formation leads to a quartz-dominated contact aureole. • Supercritical fluids have similar volatile contents as surrounding subcritical geothermal fluids. • Condensation of liquid from ascending supercritical fluids above the intrusion generates acid thermal fluids. Abstract High-enthalpy supercritical geothermal fluids were obtained from the IDDP-1 well at Krafla, Iceland, which had a discharge temperature of ∼440 °C and specific enthalpy of ∼3200 kJ kg−1. Utilization of such fluids may multiply power production from geothermal well fields. However, the origin of supercritical fluids in the roots of volcanic geothermal systems is poorly understood. Here, we propose that an important mechanism of such supercritical fluid formation is conductive heating of surrounding subcritical geothermal fluids near a shallow intrusion. Predictions from hydrologic and chemical models of supercritical fluid formation and ascent are compared with measured fluid compositions from the Krafla geothermal system. Supercritical fluids formed by close to isobaric heating of liquid geothermal groundwater display similar volatile concentrations (C, S, B, Cl, F) as the initial fluid. In contrast, the low concentrations of non-volatile elements (Si, Na, K, Ca, Mg, Al, Fe) in the supercritical fluid result from intensive, quartz-dominated mineral deposition near the magmatic intrusion during boiling of liquid to dryness. Liquid condensed out of ascending supercritical fluid has a low pH (∼2) due to the dissociation of volatile components like HCl. Such 'acid' geothermal fluids have been encountered in wells in the Krafla system. However, the chemical signatures of supercritical fluid ascent are likely to be overprinted by mixing of the acid fluids with cooler subcritical fluids, fluid-rock interaction, depressurization boiling and phase segregation. [ABSTRACT FROM AUTHOR]

Highlights • Geochemical modeling of reservoir and wellbore fluid chemistry by using PHREEQC. • Geochemical assessment of mineral scaling. • Precise estimation of gas-breakout depth for inhibitor application. • Computation of total dissolved gas pressure in reservoir. Abstract In practice, geothermal fluids are sampled under surface conditions for geochemical interpretations. However, the physical and chemical properties of geothermal waters change as the waters flow from a reservoir to the surface along the well due to processes such as mineral scaling, degassing, cooling and boiling. The objective of this study is to estimate the geochemical characteristics of water-dominated geothermal reservoirs and to model the geochemical evolution of fluids in geothermal wellbores to provide information on the parameters that contribute to sustainable energy production. A workflow was developed for commonly used non-commercial software PHREEQC and geochemical modeling approach was demonstrated for fluid samples of four geothermal wells located in the Kizildere geothermal field (SW Turkey). According to the modeled reservoir chemistry, the reservoir type in the field is water-dominated, and the sum of partial pressures of dissolved CO 2 and steam in the reservoir varies from 135–160 atm. First gas bubble depths, where an inhibitor should be injected below, were calculated for relevant flow rates of the wells as 1597, 1751, 1884 and 1579 meters. The calculated initial total calcium concentrations in the reservoir are 3.67, 5.93, 5.04 and 6.01 mg/kg. Besides calcite, 16 minerals including silica polymorphs, amphibole, serpentine, pyroxene, carbonate and phyllosilicate groups, are gained precipitation tendency under the separator conditions. To provide sustainable energy production by preventing mineral scaling in reservoirs and wells, the required parameters such as; appropriate depth for inhibitor injection in wellbore, type and initial concentration of scaling minerals, total dissolved gas and steam pressures in reservoir to limit maximum flowrate can be determined for any water-dominated geothermal field by using the proposed workflow in the PHREEQC software. [ABSTRACT FROM AUTHOR]

• The surface tensional behaviour of CTAB were enhanced by addition of P-FV nanocomposites similarly to the CTAB-Pectin systems. • The temperature and period of aging didn't obviously affect the foaming properties (foam volume and drainage half time) for the P-FV-C nanocomposites unlike the pure CTAB. • The salt content didn't alter the foam volume however the foam drainage half time was drastically decreased for CTAB. The geothermal energy industry is exploring environmental friendly alternatives for the current foaming systems used in geothermal well drilling. In this study, Pectin/ Ferric vanadate/ Cetyltrimethylammonium Bromide nanocomposites (P-FV-C) were fabricated through two stages. The structure analysis and thermal stability of the nanomaterials in both stages were confirmed by Fourier Transfer Infra-Red (FT-IR), Dynamic Light Scattering (DLS), Scanning Electron Microscope (SEM), and Differential Scanning Calorimetry (DSC). The main objective is to decrease the cytotoxicity of CTAB without losing its foaming properties by incorporating the pectin heterogeneous vanadate oxide nanocomposite (P-FV) into the CTAB foaming system structure. The best results, in terms of foaming properties and cell viability, were exhibited for P-FV-C5 when the weight ratio of P-FV to CTAB was 1:1. The cytotoxicity results revealed that the cell viability increased from 4.47 to 79.58% for 1 µg/ml of pure CTAB and P-FV-C5 respectively. The temperature and period of aging didn't obviously affect the foaming properties (foam volume and drainage half time) for the P-FV-C nanocomposites unlike the pure CTAB, of which foaming properties were drastically decreased. For CTAB (1.0 wt.%), the foam volume decreased from 700 to 300 ml and the drainage half time decreased from 30 to 16 min when the temperature increased from 150 to 200 °C after dynamic aging for 16 h. At the same previous conditions and concentration, P-FV-C5 showed stable foaming properties (foam volume = 700 ml and drainage half time= 45 min). The foam volume was decreased from 761 to 695 ml and drainage half time was stable by increasing the aging period from 8 to 24 h at 200 °C for P-FV-C5 (1.0 wt.%) while the foam volume decreased from 789 to 253 ml and the drainage half time decreased from 30 to 14 min for pure CTAB at the same conditions and concentration. Also, the drainage half time was decreased from 40 to 15 min by increasing the calcium chloride content from 1 to 5 wt.% while it was stable for P-FV-C5 nanocomposite. These results were explained based on the surface and rheological properties of the nanocomposites. The above findings indicate that the P-FV-C5 nanocomposite could attain environmental and operational success while drilling high temperature and salinity geothermal wells. [Display omitted] [ABSTRACT FROM AUTHOR]

Geothermal exploration is a complex process that spans a number of disciplines. Before a decision is made to drill a geothermal well, there is need for an extensive exploration process to determine the most suitable location. The process of evaluating and analyzing data from individual scientific disciplines can be complex and tedious. Attempts have been made at solving this problem using GIS-based tools but the uptake of these tools is often hindered by the limited knowledge of GIS by decision makers. This paper presents an approach for solving the geothermal exploration question through a web-based spatial decision support system (SDSS) that incorporates the various geosciences through a multi-criteria spatial decision analysis model. The results reveal a decision-making gap that is to be filled using a novel, automated exploration SDSS. This approach hypothesizes an easier and faster decision-making process. The research focuses on Olkaria, an active geothermal area in Kenya, East Africa and highlights a pragmatic approach to identifying priority areas for drilling. It evaluates contributions made by many disciplines in identifying potential sites ideal for harnessing geothermal energy and the gaps that emerge in an effort to synergize the results from the different disciplines. [ABSTRACT FROM AUTHOR]

A new system integrating geothermal energy into post-combustion carbon capture is proposed in this paper. Geothermal energy at medium temperatures is used to provide the required thermal heat for solvent regeneration. The performance of this system is compared with solar assisted carbon capture plant via technical and economic evaluation. A 300 MWe coal-fired power plant is selected as the reference case, and two different locations based on the local climatic conditions and geothermal resources are chosen for the comparison. The results show that the geothermal assisted post-combustion carbon capture plant has better performances than the solar assisted one in term of the net power output and annual electricity generation. The net plant average efficiency based on lower heating value can be increased by 2.75% with a thermal load fraction of about 41%. Results of economic assessment show that the proposed geothermal assisted post-combustion carbon capture system has lower levelized costs of electricity and cost of carbon dioxide avoidance compared to the solar assisted post-combustion carbon capture plant. In order to achieve comparative advantages over the reference post-combustion carbon capture plant in both locations, the price of solar collector has to be lower than 70 USD/m 2 , and the drilling depth of the geothermal well shall be less than 2.1 km. [ABSTRACT FROM AUTHOR]

The thermal evolution of collisional orogens is largely controlled by their kinematic and burial/exhumation history, where sedimentation and erosion rates, as well as shear heating and deep heat flow supply conditions for the temperature distribution, fluid flow and the associated fluid-rock interactions. The aim of our research is to understand this coupled kinematic and thermal evolution to ultimately infer the conditions favourable for subsurface geo-resources. We achieve this aim by means of numerical modelling and its application to one of the best available orogenic indentation examples, which is the Dinarides Mountains chain in Central Europe. Based on the analysis and modelling of an integrated onshore and offshore geological cross-section, we quantified the shortening, erosion/exhumation and sedimentation/burial rates, maturity of potential petroleum source rocks and the gross potential for sustainable geothermal resources. The coupled kinematic/thermal modelling revealed a general pattern of heat flow variations associated with crustal deformations. The hanging-wall and upper parts of the footwalls show increased conductivity and heat flow during episodes of thrusting, whereas the deepest parts of footwalls have lower heat flow values. Fluids are observed to migrate towards the foreland during the latest Cretaceous – Early Oligocene thrusting. The largest amounts of post-Middle Miocene shortening took place in the SE external parts of the orogen, where deep-sourced fluid ascent took place towards the foreland. In this region, significant footwall burial enhanced the maturation of potential source rocks. Modelling results infer a considerable hydrocarbon potential for the Dalmatian unit and the South Adriatic basin. The kinematic and thermal model combined with geothermal well design and well performance calculations infer a viable geothermal energy potential for the Dalmatian and High-Karst units. Results of this novel workflow allowed to quantify the orogenic kinematic and thermal history, and its bearing on conventional and sustainable geo-resources. • Coupled kinematic and thermal processes in collisional orogens. • Geodynamic processes influence on thin- and thick-skinned tectonics. • Implications of heat evolution for subsurface geo-resources. • Shortening, exhumation, erosion and sedimentation during the Dinarides evolution. [ABSTRACT FROM AUTHOR]

High pressure and high temperature (HPHT) conditions in geothermal wells have necessitated the need to develop thermally stable geothermal drilling mud systems to combat potential drilling complications. This is because mud fluids degrade under HPHT conditions due to high temperature effects. This study therefore aims to establish the optimum concentration of a cationic surfactant that would successfully modify the surface of silica nanoparticles and thereafter, evaluate the performance of modified nano silica as a rheological and filtration property enhancer in water-based muds (WBMs). The surface of silica nanoparticle was successfully modified by adding Hexadecyltrimethylammonium bromide (CTAB) to silica solution. Different mud formulations containing modified nano silica with varying zeta potential values, SNP3 -S2, SNP3 -S4, SNP3 -S5, SNP3 -S6, and SNP3 -S7 with -17.7 mV, 20 mV, 28.2 mV, 35.4 mV, and 37.1 mV respectively were investigated. Results showed that modified nano silica with the highest absolute value of zeta potential enhanced drilling mud rheology as temperature increased from 149°C to 232 °C. The optimal amount of CTAB was found to be between 1.0 and 2.0 wt.%. Filtration loss was reduced by 11.4, 17.6, and 29.5% on average for mud samples SNP3-S5, SNP3-S6, and SNP3-S7, respectively, at all temperatures. Mud cake thickness was reduced by 19.9, 11.6, and 28.7% on average by mud samples SNP3-S5, SNP3-S6, and SNP3-S7 respectively at all temperatures. [ABSTRACT FROM AUTHOR]

Geothermal energy is the thermal energy stored within earth. In other words, geothermal energy is the only alternative source of energy independent of the climate. This makes geothermal energy a more reliable source of energy which will help the world meet the minimum level of power demand. Although geothermal energy is independent of the climate, it is highly dependent on the underlying local, global, and hydrological frameworks. It is utilized for power (electricity) generation and/or directly used for heating purposes. While geothermal energy has a lot of potentials and is being utilized for more than a century, it faces several challenges which need to be addressed to make it more economical. This paper compares Oil and Gas well construction with Geothermal well construction to highlight the key differences between them. Furthermore, Geothermal cementing challenges are discussed in detail from a well integrity perspective. The impact of high temperature (up to 1000 °C), geothermal fluids, and corrosive gases (CO 2 and H 2 S) on geothermal cement are examined. The research and development carried out to mitigate these cementing challenges are meticulously reviewed and future research recommendations are presented. This review paper will not only help the Oil and Gas cementing personnel have an in-depth understanding of Geothermal cementing but also motivate them to use their expertise to solve the existing geothermal cementing challenges and accelerate energy transition process. • Detailed guide for Oil & Gas cementing personnel to understand the geothermal well construction challenges and solve them. • Focuses on geothermal cementing challenges, existing solutions, and its effect on long-term well integrity. • Review highlights the use of alternative cement systems with lower carbon footprints than the Portland cements. [ABSTRACT FROM AUTHOR]

• Comprehensive review of conservation equations for geothermal wellbore models • Identification of models that incorrectly conserve momentum and energy • Investigation of the impact of approximating momentum and kinetic energy terms A wellbore simulator is an important tool for understanding flow in geothermal wells, however, the literature on the topic is confusing because previous wellbore simulators have been based on a variety of versions of the equations for conservation of mass, momentum and energy. This lack of consistency in describing the behaviour of flow in a geothermal well makes it unclear as to whether some models correctly conserve key quantities and presents difficulties when comparing models. This study aims to give clarity by providing a comprehensive review of conservation equations used in modelling both transient and steady multiphase flow in a geothermal wellbore. We present as a standard for comparison a complete, physically accurate three-equation model for transient flow in a geothermal wellbore. Two of the four previous transient geothermal wellbore simulators use this three-equation model, while the other two simulators are based on approximate equations that do not fully conserve all quantities. We also review previous steady-state geothermal wellbore simulators and find that some are based on mathematical models that do not correctly conserve key quantities. Some models approximate the momentum flux term using average variables, while others incorrectly account for the effect of changes in cross-sectional area on momentum flux. Our analysis shows that both assumptions can have a significant impact on simulation results under certain conditions, however, under normal operating conditions, these differences are relatively small. [ABSTRACT FROM AUTHOR]

There are numerous oil fields that are approaching the end of their lifetime and that have great geothermal potential considering temperature and water cut. On the other hand, the oil industry is facing challenges due to increasingly stringent environmental regulations. An example of this is the case of France where oil extraction will be forbidden starting from the year 2035. Therefore, some oil companies are considering switching from the oil business to investing in geothermal projects conducted on existing oil wells. The proposed methodology and developed conversions present the evaluation of existing geothermal potentials for each oil field in terms of water temperature and flow rate. An additional important aspect is also the spatial distribution of existing oil wells related to the specific oil field. This paper proposes a two-stage clustering approach for grouping similar wells in terms of their temperature properties. Once grouped on a temperature basis, these clusters should be clustered once more with respect to their spatial arrangement in order to optimize the location of production facilities. The outputs regarding production quantities and economic and environmental aspects will provide insight into the optimal scenario for oil-to-water conversion. The scenarios differ in terms of produced energy and technology used. A case study has been developed where the comparison of overall fields and clustered fields is shown, together with the formed scenarios that can further determine the possible conversion of petroleum assets to a geothermal assets. [ABSTRACT FROM AUTHOR]

• Fluid systems with high lubricity and plugging performance are investigated. • HTHP drilling fluid system is selected for the experiments. • Highest lubricity performance is observed in fluid compositions containing LUBE-1. • Lubricity performance of the fluids are decreased with addition of contaminants. Drilling in a lost circulation zone has long been a challenge in geothermal wells due to its strong potential for high torque and wellbore instability. Particularly in deviated, extended reach and horizontal wells, frictional forces between drill string and wellbore or casing may be high enough to interfere with running the pipe in and out of the hole. These forces may also increase the torque and the stress on drill string which may end up with severe problems like stuck pipe and lost in hole. High-temperature high-pressure (HTHP) drilling fluids design, which minimize loss rates and friction values, is critical for the success in the face of these challenging drilling practices. The goal of this research is to provide a solution-oriented approach to torque and lost circulation problems in potential seepage and partial loss zones in geothermal wells; by developing efficient water-based drilling fluid compositions. Non-aqueous fluids (NAFs) are known to have the highest lubricity performance. However, application of these drilling fluid systems is limited because of high cost and environmental constraints. Hence, water-based drilling fluids are good candidates for replacing conventional NAFs. This paper investigates water-based drilling fluid compositions with high lubricity performance, HTHP resistance and high loss zone plugging performance. The design and selection of HTHP drilling fluid system have been the focus of experimental studies and worldwide field experience. Several chemical commercial lubricants are added in this fluid system to find the compositions for the highest lubricity performance closest to NAF systems. Also, considering the formation characteristics, environmental constraints, reservoir contamination concern and drilling limitations; proper fluid compositions are formulated to plug the potential seepage and partial loss zones and reduce the differential-sticking tendency by using proper lost circulation materials and lubricants. This study aims to encourage the geothermal drilling industry worldwide, to utilize the developed drilling fluid compositions with enhanced lubricity and loss zone plugging performance together to overcome related major drilling problems. Results reveal that lubricity and pore plugging characteristics of the selected compositions are highly innovative and noteworthy to be used in field applications for geothermal drilling industry. [ABSTRACT FROM AUTHOR]

With the growing interest in geothermal energy as a renewable and sustainable energy source, nowadays engineers and researchers are facing technological and environmental challenges during geothermal wells' operation or energy recovery improvement by optimizing surface installations. One of the major problems encountered is the degassing of geothermal brines which are often loaded with dissolved gases, resulting in technical problems (scale formation, corrosion, reduced process efficiency, etc.) and environmental problems through the possible emission of greenhouse gases (CO2, CH4 and water vapor) into the atmosphere. In this work, a method to predict, from readily available information such as temperature and GLR, the bubble point pressure of geothermal fluids as well as the GHG emission rate depending on the surface conditions is presented. This method is based on an extended version of the Soreide and Whitson model with new parameters optimized on the solubility data of several gases (CO2, CH4, N2, O2 and H2) in brine (NaCl + CaCl2 + KCl). The developed approach has been successfully used for the prediction of water content of different gases and their solubilities in different types of brines over a wide temperature and pressure range, and has been applied for the prediction of bubble point pressure and GHG emissions by comparing the results with available industrial data of geothermal power plants including the Upper Rhine Graben sites. [ABSTRACT FROM AUTHOR]

• A novel tool Casinteg was developed for efficient geothermal well analyses. • Casing creep and plasticity behaviours are important for geothermal well designs. • Excellent agreement between Casinteg and Abaqus models was obtained. • Casinteg was used to analyse global structure behaviour of IDDP-1 well. • Efficiency and flexibility of Casinteg are assets for casing system design. In geothermal energy, a huge energy potential lies in hydrothermal reservoirs close to magma where ultra-high temperature fluids (>450 ° C) can be harnessed. Well casing system needs to be properly designed to ensure its integrity during its service lifetime. There currently exist neither any commonly accepted design tools nor standards regulating geothermal well design under such conditions. In this study a novel tool, Casinteg, was developed for structural analyses of geothermal wells. The tool is intended to bridge the gap between simplified analytic solutions and complex FE-based commercial software. The reliability and efficiency of the constitutive models implemented in Casinteg were verified in comparison with Abaqus. Casinteg's capability for structural analyses of full geothermal wells was preliminarily investigated, using IDDP-1 well as a case study. The calculated stress in the production casing was in a good agreement between Casinteg and Ansys models, while the computational time of Casinteg simulations was within minutes. Further developments are still needed. However, preliminary results were encouraging and have demonstrated the benefit of Casinteg for efficient structural analyses of full geothermal wells. [ABSTRACT FROM AUTHOR]

• Shallow and medium geothermal systems are underrepresented in life-cycle assessments. • The life-cycle environmental impacts of geothermal heating and cooling are analyzed. • Geothermal heating and cooling are fit for decarbonization of the building sector. • Most other impacts are lower than for fossil fuels, except for mineral resource scarcity. • Decentralized connected heat pumps have lower impacts than district heating. Geothermal heating and cooling from a depth of 10–3′500 meters have considerable decarbonization potential but understudied life-cycle environmental impacts. We quantified the life-cycle impacts of six heating and cooling configurations from shallow to medium-depth geothermal wells with connected, decentralized heat pumps and district heating and cooling in the State of Geneva. Shallower systems with connected heat pumps have better environmental performance than systems with district heating, whereas shallow systems with free cooling perform best for cooling. These environmental impacts are lower than those of fossil fuels, except for mineral resource scarcity, especially with decentralized heat pumps and free cooling. [ABSTRACT FROM AUTHOR]

• Drilling fluids experience of 267 deep geothermal wells in Turkey is summarized. • Six WBM types are selected and detailed information is presented. • Drilling fluid related risks and mitigation guidelines are summarized. • Polymers with higher temperature stability are vital for geothermal wells. • Use of WSM is required to drill through ophiolitic serpentine formation. Joined the 1 GW installed capacity club in 2017, Turkey has undeniable production and potential for geothermal energy, ranking top 5 worldwide. Harnessing geothermal energy has many challenges, from planning to commercial phases. This study features the challenges, experiences and latest advances in drilling fluids utilized in geothermal well construction process in Turkey; focusing to provide a comprehensive information about drilling fluids systems and their design principles in geothermal wells in Turkey. GEOS act as a major player in Turkish geothermal drilling industry; providing drilling and completion fluids, solids control equipment and waste management services; having drilled more than 250 deep geothermal wells in utmost challenging downhole environments of Turkish geothermal fields with major operators. Drilling geothermal wells comes along with several challenges. Most important of which could be high temperatures, relatively high pressures and some of the wells having tough lithologies to drill through. Providing wellbore stability across dispersive shales or pressurized ophiolitic formation requires special attention in planning and execution phases. Another special attention has been given to minimize formation damage in reservoir intervals of geothermal wells. Therefore, different options of reservoir drilling fluids are presented and discussed in detail. Drilling fluids systems used in geothermal wells have evolved over the last decade and tailored to suit the challenges to be faced, not only in top hole and intermediate intervals, but also in reservoir intervals. Main objective of this paper is to share the knowledge and experience gained during the learning curve over the years; extensive laboratory studies and field case studies for geothermal well drilling fluids in Turkey are presented. [ABSTRACT FROM AUTHOR]

• Thermal, hydraulic and geochemical properties are assessed in a geothermal system. • High thermal conductivity formations are analyzed for thermal anomalies. • Potential power production is calculated. • The potential for lithium production is considered. Low-temperature geothermal power plants have great potential to provide baseload electricity worldwide. However, the technology is new and untested, and the systems require a significant financial investment. Site-specific feasibility studies are required to draw together available data and inform developers of production potential and challenges. This study applies coupled thermal, hydraulic, and geochemical modeling to characterize a horizontal geothermal well system in the Williston Basin. This study targeted thermal anomalies overlying 370 m thick halite and dolomite formations from the Devonian period. The halite and dolomite produced a 6°C thermal anomaly, or 16°C km−1 increase in the thermal gradient. A >5.0 MW power plant was achieved when targeting the Dawson Bay formation. A fractured, horizontal well in the Bakken formation was re-entered for injection, providing a savings of up to 40% of drilling costs. The geochemical analysis allowed for the calculation of potential precipitates in the production casing, and consideration of mitigation methods. In addition, the co-production of lithium was identified as potentially profitable in the Dawson Bay Formation. Considering the available resources and assets provided unique data to inform the development of a geothermal system in the Williston Basin. [ABSTRACT FROM AUTHOR]