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Bleed‐off and shut‐in of injection have been implemented in different Enhanced Geothermal Systems (EGS) in an attempt to mitigate the induced seismicity at and after the injection stop. This article tackles the controversial discussion on the mitigation of the post‐injection induced seismicity through ending fluid injection by either a bleed‐off or a shut‐in. Both scenarios failed to mitigate the occurrence of large magnitude earthquake after stopping injection in numerous EGS. The two protocols are compared by using a seismological forecasting methodology coupled with a hydro‐mechanical model reproducing flow, poroelastic stress and fault failure in a domain including a discrete fault network based on Basel EGS (Switzerland, 2006). Unlike bleed‐off, shut‐in mitigates early post‐injection seismicity by smoothly reducing pressure, and consequently poroelastic stress changes in the modelled Basel EGS. Although post‐injection pore pressure diffusion eventually reaches distant faults and destabilizes them, seismicity is not initiated according to our simulation forecasting. Plain Language Summary: Fluid injection induces seismicity in Enhanced Geothermal Systems (EGS), which continues to occur when injection stops and days after. Different protocols have been proposed to mitigate the frequency and magnitude of the post‐injection seismic events, particularly well bleed‐off (opening of the well with consequent backflow and pressure drop to initial levels) and shut‐in (suddenly stopping injection). However, applying one or the other methods did not efficiently mitigate the occurrence of the largest magnitude earthquake after the stop of injection. This study compares the effects of the two protocols on the stability of a fault network through the forecasting of the seismicity based on a numerical model reproducing the main involved physical processes. Bleeding‐off the well induces abrupt pressure drops, which reactivates the faults in the vicinity of the well. Shut‐in, on the other hand, mitigates this process but does not control the pore pressure diffusion that continues to propagate in the reservoir after the stop of injection. Simulation results show that a progressive continuous decrease of the injection pressure followed by a shut‐in better mitigates the early reactivation of the faults without inducing late seismicity, thus lowering the risks of cancellation of EGS projects due to post‐injection induced seismicity. Key Points: The largest magnitude earthquake may be induced after injection ends by pore pressure diffusion and poroelastic relaxation on large faultsAlthough well bleed‐off mitigates reservoir pressurization in the vicinity of the well, the abrupt pressure changes induce seismicityA progressive decrease of injection pressure followed by a definitive shut‐in mitigates post‐injection seismicity in the model of Basel [ABSTRACT FROM AUTHOR]

Emergency General Surgery (EGS) represent a wide spectrum of diseases with high complication and mortality rates. Race, insurance, and socioeconomic status have been associated with mortality in EGS patients. Acute care surgery (ACS) models have previously shown improved outcomes for EGS patients. We hypothesized that transition to an ACS model would increase access to care for underserved and higher risk EGS patients in a community hospital, without a change in mortality. This retrospective cohort study included adult EGS patients from 2017 to 2021 with current procedural terminology (CPT) codes of colectomy, small-bowel resection, peptic-ulcer surgery, appendectomy, or cholecystectomy. In July 2020, the hospital transitioned from a traditional model to an ACS model. Patients were analyzed for 42-month before (pre-ACS) and 18-month after (post-ACS) transition. Primary outcome was mortality; secondary outcomes were 30-day postoperative emergency department visits and readmission. We analyzed 467 pre-ACS and 238 post-ACS patients. After transition, patients were more likely to be Black, older, self-pay, and have higher Elixhauser Comorbidity Index (ECI) scores. Rates of cholecystectomies increased and appendectomies decreased after transition. Adjusting for age, race, and ECI, there were no changes in 30-day all-cause mortality (0.9% versus 2.1%, P = 0.63), length of stay (2.7-days versus 3-days, P = 0.91) and rate of postop emergency department visits (7.5% versus 11.3%, P = 0.16). There was a significant increase in hospital readmission after the ACS transition (5.1 versus 10.5%, P = 0.001, odds ratio 5.3). After implementation of an ACS model, we found an increase in EGS patients who were older, Black, underinsured, with higher ECI without change in mortality. Implementation of ACS models at community hospitals may increase access to quality care for underserved and higher risk patient populations. [ABSTRACT FROM AUTHOR]

The relative performance of H2O and sCO2 as geothermal working fluids (GWFs) in liquid-dominated enhanced geothermal systems (EGSs) was investigated in this study. Such systems rely on the injection of GWFs (geothermal working fluids) to sustain geothermal energy recovery, which is dominated by conduction-based heat exchange from the rock to the GWF in the hydraulic fracture. H2O is currently the only GWF considered for EGS operations, but supercritical CO2 has been proposed as a potential GWF because of its lower density and viscosity, which lead to the hypothesis of potentially significant thermal energy recovery. However, H2O appears to have an initial advantage because of its significantly higher thermal conductivity. We compared the performance of H2O and SCO2 as GWFs in a 3D stencil (minimum repeatable element) of an EGS involving a hydraulic fracture connecting the injection and the production wells, the main body of the EGS rock that provides the heat source, and boundaries that are sufficiently distant from the main body of the main body of the rock to maintain constant pressure and temperature conditions over a 30-year period of EGS operations In our studies we considered variations in the initial reservoir temperature, in the injection method (at a constant-rate and at a constant bottomhole pressure) and in the reservoir permeability, in an effort (a) not only to compare the EGS performance of H2O and sCO2 as GWFs but also (b) to determine the conditions (if any) under which sCO2 can be more effective than H2O. The results of the study indicated the overwhelming superiority of H2O as a GWF under any and all of the conditions covered by the study, producing fluids at dependably much higher temperatures and yielding invariably drastically higher energy recovery than sCO2 despite the consistently higher GWF injection and production rates attained with sCO2. [ABSTRACT FROM AUTHOR]

The projection-based embedded discrete fracture model (pEDFM) and its counterpart, the embedded discrete fracture model (EDFM), have become standard tools for the depiction of the fractures in reservoir simulations. Despite their widespread use, there are still some unclear areas in modeling the complex processes of mass and heat transfer within fractured reservoirs, particularly in both single-phase and multiphase flow scenarios. Our research introduces a numerical methodology for simulating the mass and heat transfer in fractured reservoirs which is developed by extending the framework of the pEDFM and EDFM. To gauge the effectiveness of these models, we devised two cases which were designed to evaluate the adaptability of the pEDFM and EDFM in scenarios involving an ultra-low permeability fracture or a high permeability fracture under single-phase and multiphase conditions. By using local grid refinement (LGR) as a reference, the results of the pEDFM were in reasonably good agreement with the LGR in terms of pressure, temperature, and saturation distributions. This comparison suggests that the pEDFM has a significant advantage in depicting the mass and heat transfer at the matrix–fracture interface compared to the EDFM. Furthermore, a comprehensive analysis of the flow trajectories in both the pEDFM and EDFM provided a reasonable explanation for their differences. Furthermore, the numerical applications involving the heat extraction of Enhanced Geothermal Systems (EGSs) and the water flooding in fractured reservoirs illustrate the adaptability of the pEDFM in the numerical simulation for complex geological conditions. The insights and conclusions obtained in this paper can enhance our understanding of the distinctions between the pEDFM and EDFM, aiding in the selection of the most suitable method for characterizing the fractures in numerical simulations. [ABSTRACT FROM AUTHOR]

Geothermal resources are a promising approach to clean renewable energy; 90% of them are deep reservoirs of hot dry rock that require hydraulic fracturing to create a network of connections among wells to enable efficient heat exchange, known as an Enhanced Geothermal System (EGS). The Pohang EGS project in south Korea led to a devasting Mw5.5 earthquake, triggered by the reservoir’s EGS stimulation, the largest earthquake known to have been induced by EGS development. Detailed investigations have been conducted to understand the cause of the Pohang earthquake; the conclusion has been that overpressurized injected fluids migrated into an unknown fault triggering this large earthquake. Detailed velocity images for the source zone of the 2017 Pohang earthquake, which could be helpful for further understanding its inducing mechanism, are unavailable. However, we have assembled detailed aftershock data recorded by 41 local stations installed within about three months after the Mw5.5 Pohang earthquake, and have then applied the Vp/Vs model’s consistency-constrained double-difference seismic tomography method to determine the high-resolution three-dimensional Vp (compressional wave velocity), Vs (shear wave velocity), and Vp/Vs models of the source region that we report here, as well as earthquake locations within the source region. The velocity images reveal that the deep source area of the 2017 Pohang earthquake is dominated by low Vp, high Vs, and low Vp/Vs anomalies, a pattern that can be caused by overpressurized vapors due to high temperatures at these depths. Based on aftershock locations and velocity features, our studies support the conclusion that the 2017 Pohang earthquake was triggered by injected EGS fluids that migrated into a blind fault.

Exploring the heat recovery performance of enhanced geothermal systems ( EGS) engineering is essential to improve system heat production efficiency and extend reservoir life. Based on the geological structure, lithology, geothermal geological data and laboratory data of Chang 27 well in the northern Yitong Basin, the hydro-thermal coupling numerical model of three horizontal wells and the prediction model of thermal reservoir capacity based on BP neural network were established with 4 054 ~ 4 168 m granite as the thermal reservoir, and the main factors affecting the performance and efficiency were studied. The results show that the relative errors of temperature, enthalpy difference and pressure difference predicted by BP neural network model and the numerical model are basically no more than ± 1. 0%, ± 2. 0% and ± 3. 0%, and the prediction accuracy is high. The factors that have a greater impact on the system production temperature are well spacing and injection rate, and the factors that have a greater impact on the system power generation efficiency are injection rate and fracture permeability. Considering the interaction of all influencing factors, the extraction scheme can be chosen for geothermal energy extraction using three horizontal wells with a well spacing of 600 m, injection temperature of 60 °C, injection rate of 23 kg / s, and fracture permeability of 1 × 10 -10 m 2 . The economic life of the system under this working condition can reach 32 years, and the cumulative power generation capacity is 605. 9 GW·h, which is 7. 4% higher than the base model. [ABSTRACT FROM AUTHOR]

While particularly during the 1970s and 1980s, socialist Yugoslavia maintained close contact with the neighbouring European Economic Community, its most important foreign trade partner at the time, this did not preclude Yugoslavia's non-aligned foreign policy. Based on newly accessible documents from the federal foreign affairs authorities, the first part of the paper analyses Belgrade's official position vis-à-vis Brussels in the late 1980s and early 1990s. Namely, with the fall of the Berlin Wall, which reduced Yugoslavia's geopolitical relevance, and the growing wariness of the European commissioners with regard to its complicated internal affairs situation, the prospect of Yugoslavia attaining associate or even full membership in the European Economic Community - aspirations particularly promoted by the reform government of Ante Marković - proved unrealistic. In the northernmost Yugoslav republic, which was also most actively engaged in an economic exchange with the European Economic Community, frustration over sluggish negotiations on the part of federal authorities with Brussels and especially the comprehensive integration process introduced in the European Economic Community by the Single European Act prompted an autonomous search for new paths to the emerging largest global economic bloc. The second part of the article draws on materials of republican provenance to provide an analysis of the imaginary of Europeanism, as well as of the technocratic strategies adopted to approximate the Slovenian/Yugoslav legislation and standards (the so-called 1990 White Paper), which was a major focus of the last Slovenian socialist government and the reforming League of Communists. Although the catchphrase of the time, "Europe Now!", was interpreted in some parts of Yugoslavia as a call for Slovenia to immediately and independently join the European Economic Community, the Slovenian late-socialist establishment still allowed for the possibility of Slovenia integrating into Europe within the framework of Yugoslavia. [ABSTRACT FROM AUTHOR]

High-energy beta-ray sources generate bremsstrahlung photons in the building materials, generated by the radioactive nuclides inside the nuclear reactor buildings emitted by the Fukushima Daiichi nuclear reactor accident. Therefore, evaluating the bremsstrahlung dose subjected to the workers in the building is crucial for radiation protection. The precision for assessing the bremsstrahlung dose was investigated by comparing the Particle and Heavy Ion Transport code System (PHITS) and the GEometry ANd Tracking (GEANT4) simulation code results. Behind various shielding plates (lead, copper, aluminum, glass, and polyethylene with multiple thicknesses), the water cylinder was set to obtain the absorbed dose and the deposited energy spectrum by the bremsstrahlung photons. In comparing the deposited energy spectrum, the spectral shapes have consistent trends. Below several tens of keV, a peak is observed in the PHITS spectrum for lead. While comparing the absorbed dose, most of the results from both codes correlate within an ~10% difference for 2.280 MeV beta-ray sources and an ~20% difference for 0.5459 MeV beta-ray sources, except for ~30% for 20 mm thick lead. Although some differences occurred, the evaluation results of both codes correlated well with the above precision. [ABSTRACT FROM AUTHOR]

Abstract Bleed‐off and shut‐in of injection have been implemented in different Enhanced Geothermal Systems (EGS) in an attempt to mitigate the induced seismicity at and after the injection stop. This article tackles the controversial discussion on the mitigation of the post‐injection induced seismicity through ending fluid injection by either a bleed‐off or a shut‐in. Both scenarios failed to mitigate the occurrence of large magnitude earthquake after stopping injection in numerous EGS. The two protocols are compared by using a seismological forecasting methodology coupled with a hydro‐mechanical model reproducing flow, poroelastic stress and fault failure in a domain including a discrete fault network based on Basel EGS (Switzerland, 2006). Unlike bleed‐off, shut‐in mitigates early post‐injection seismicity by smoothly reducing pressure, and consequently poroelastic stress changes in the modelled Basel EGS. Although post‐injection pore pressure diffusion eventually reaches distant faults and destabilizes them, seismicity is not initiated according to our simulation forecasting.

Abstract Stimulation techniques to enhance fluid pathways are an important tool to make geothermal projects economically feasible. So far, hydraulic stimulation is used almost exclusively for reservoir-wide improvement of the permeability, but induced seismicity poses a challenge. Chemical stimulation on the other hand has been limited to the close vicinity of the borehole and has barely been considered for the creation of enhanced geothermal reservoirs. However, retardation mechanisms reducing the chemical reaction rate can be used to increase the radius of the chemical stimulation thus enabling a reservoir-wide enhancement of fluid pathways. In this work, we review the technologies of retardation mechanisms for chemical stimulation in geothermal systems and identify five groups of retardation techniques: (i) causing impaired mobility of the acid, e.g., by gelling agents; (ii) causing an impaired dissociation, e.g., by the in-situ generation of the reactive compounds; (iii) blocking the mineral surface area, e.g., by alternating injections of pad fluids and acids; (iv) reducing the reaction rate constant, e.g., by cooling; and (v) changing the chemical equilibrium through chelating agents. We found that most applications are currently based on the use of impaired dissociation, but present research focuses on the development and application of chelating agents. Most of these retardation techniques are adopted from the hydrocarbon industry, but there are several techniques that have not been applied in the geothermal context so far for various reasons. We identify a distinctive lack of in-depth descriptions of the retardation techniques in various studies—mostly to protect intellectual property. However, in the light of public concern regarding fracking techniques and to independently assess potential environmental hazards, scientific examination of proposed techniques is indispensable.

The radioactive decay of isotopes is one of the most important sources of heat in the Earth's interior. The main radiogenic elements in the crust are U, Th, and K in granitoids. Radiogenic granites are becoming increasingly important as they support the development of the renewable energy sector. This study provides an in-depth review of the development of Enhanced Geothermal Systems (EGS) technology. Many countries, such as France and the UK, have initiated and contributed to energy production using EGS technology. In addition, this study calculates the potential production capacity of radiogenic granites in the Eastern Pontide Oraganic Belt (EPOB) and assesses their significant contribution to the Turkish economy in line with the Sustainable Development Goals (SDGs). The total area of radiogenic granites within the EBOP is 7116.35 km2 and these granites contain average concentrations of U 3.25 ppm, Th 16.44 ppm, and K 3.7%. The plutons studied can generally be classified as medium to low heat producing granitoids. Ayeser, Camiboğazı, and Ayder (3.36-6.98 µW/m3), which are close to the average heat production value of the continental crust (5 μW/m3), may be suitable areas for EGS. Currently, EBOP granites have the capacity to produce 61 x 109 kWh of electricity. In addition to electricity, heat from granites can be used for other applications such as space heating and greenhouse cultivation.

Stimulation techniques to enhance fluid pathways are an important tool to make geothermal projects economically feasible. So far, hydraulic stimulation is used almost exclusively for reservoir-wide improvement of the permeability, but induced seismicity poses a challenge. Chemical stimulation on the other hand has been limited to the close vicinity of the borehole and has barely been considered for the creation of enhanced geothermal reservoirs. However, retardation mechanisms reducing the chemical reaction rate can be used to increase the radius of the chemical stimulation thus enabling a reservoir-wide enhancement of fluid pathways. In this work, we review the technologies of retardation mechanisms for chemical stimulation in geothermal systems and identify five groups of retardation techniques: (i) causing impaired mobility of the acid, e.g., by gelling agents; (ii) causing an impaired dissociation, e.g., by the in-situ generation of the reactive compounds; (iii) blocking the mineral surface area, e.g., by alternating injections of pad fluids and acids; (iv) reducing the reaction rate constant, e.g., by cooling; and (v) changing the chemical equilibrium through chelating agents. We found that most applications are currently based on the use of impaired dissociation, but present research focuses on the development and application of chelating agents. Most of these retardation techniques are adopted from the hydrocarbon industry, but there are several techniques that have not been applied in the geothermal context so far for various reasons. We identify a distinctive lack of in-depth descriptions of the retardation techniques in various studies—mostly to protect intellectual property. However, in the light of public concern regarding fracking techniques and to independently assess potential environmental hazards, scientific examination of proposed techniques is indispensable. [ABSTRACT FROM AUTHOR]

How induced seismicity in deep geothermal project (enhanced geothermal systems, EGS) is controlled by fluid injection is of central importance for monitoring the related seismic risk. Here we analyze the relationship between the radiated seismic energy and the hydraulic energy related to the fluid injection during several hydraulic stimulations and circulation tests at Soultz‐sous‐Forêts geothermal site. Based on a harmonized database, we show that the ratio between these energies is at first order constant during stimulations and of the same magnitude independently of the stimulation protocol and injection depth. Re‐stimulations are characterized by a sharp evolution of this ratio during injection which ultimately converges to the characteristic value of the reservoir. This supports that the seismicity is caused by the relaxation of the pre‐existing strain energy in the stimulated volume, rather than by the deformation generated from fluid injection. The ratio appears as an intrinsic large‐scale property of the reservoir that can be assessed at the very beginning of the first stimulation. Based on this property, we suggest a way to predict the largest magnitude of the induced seismic events knowing the maximum targeted hydraulic energy of the injection. Plain Language Summary: Monitoring and predicting fluid‐injection‐induced seismicity is a major concern for the development of the geothermal energy. Several geothermal sites have shown a linear relationship between the radiated seismic energy and the hydraulic energy, suggesting that these two quantities are useful for seismic monitoring and prediction. Here we study the relationship between these two quantities for different fluid injections carried out in the Soultz‐sous‐Forêts enhanced geothermal systems reservoir to see if it remains similar despite the changes and setting in the injection strategy (flow‐rate, pressure of the injected fluid) and depths. Based on a harmonized database, we show that the ratio between the radiated seismic energy and hydraulic energy is at first order constant in time during stimulations and of the same magnitude independently of the stimulation strategy and depth. This ratio can then be seen as an intrinsic large‐scale reservoir property that can be estimated from the early stages of the first stimulation. Using this reservoir property, we propose a method for predicting the maximum magnitude of induced seismic events given the maximum hydraulic energy planned. Key Points: Homogenization over multiple stimulations at the Soultz‐sous‐Forêts enhanced geothermal system site of the seismic moment estimates of the induced seismicityThe ratio of the radiated seismic energy and the hydraulic energy is shown to be constant during stimulationsThis ratio can be seen as a reservoir property describing its seismic response to fluid injection and is used to predict the largest magnitude of induced earthquakes [ABSTRACT FROM AUTHOR]

Identifying distributed strain sensing (DSS) patterns (or signatures), particularly those arising from different hydraulic fracture geometries, has gained significant attention and research effort. Recent works have generated a catalogue of signatures for planar hydraulic fractures in an elastic rock formation. Yet, in numerous cases (e.g., fault motion and some geothermal reservoir stimulation), the main mode of deformation is a shear on a fracture or a network of natural fractures (particularly during low pressure injection/circulation). However, the specific fiber signatures that result from such shear deformation have not been studied. In this study, we use a three-dimensional poroelastic hydraulic fracture simulator to capture the strain signatures resulting from the shear deformation of fractures in various orientations with respect to the monitoring well. Five key cases are examined: one where the fracture strike is perpendicular to the fiber, another with the strike running parallel to the fiber, a third case where the fracture strike is at 45 degrees to the fiber, a fourth case with a strike slip fault perpendicular to the fiber, and a fifth case where fiber is intersecting the fracture. Theoretically and physically meaningful results were obtained in all five cases, which completely differ from the heart-shaped signature of tensile fracture propagation. It was discovered that the strain pattern changes with the shear deformation direction with respect to the fiber. The model is then used to simulate the response of a fracture network at Utah FORGE to injection to assess whether a signature might be expected in response to the planned injection and circulation rates, and, if so, what strain pattern might be expected. The simulation confirms that a strain response can indeed be observed. More importantly, the fiber response that would be detected in the monitoring well would be a combination of strain signatures from dilation and shear deformation of differently oriented natural fractures. The results in this study provide useful insights on the application of fiber to other stimulation and/or circulation scenarios where shear deformation of a fracture or fracture network plays a major role. [ABSTRACT FROM AUTHOR]

A comparative numerical analysis of the thermohydraulics of an enhanced geothermal system (EGS) project in Türkiye in Dikili area is presented. The fractured granodiorite is modelled as porous media, utilizing the numerically suggested data of other authors for the corresponding hydraulic characteristics. As the heat transmission fluid, two different mediums are alternatively considered. These are the more classical medium, water and the supercritical Carbon Dioxide (sCO2). Transient calculations are performed for a time period of twenty years, comparing the temporally developing results obtained for water and sCO2 with each other. Based on modeling parameters and assumptions, higher production temperatures are observed with sCO2, in comparison to water, implying an advantage for sCO2 usage as a working fluid in EGS. This is accompanied by the further advantage of a lower pressure drop for sCO2. On the other hand, the temperature advantage is relativized by the lower specific heat capacity of sCO2 causing a decrease in the production thermal power. In general, the present re found to be encouraging for a further and more detailed analysis of the employment of sCO2 as working fluid in EGS.

Abundant geothermal energy can be harvested from deep, low-permeability rocks using an enhanced geothermal system (EGS) that relies on an artificially created permeable fracture network through cold water injection. In this study, a two-way coupling technique for thermo-hydromechanical modeling was used to simulate hydraulic fracture propagation in an EGS. The transient heat and fluid flow in porous media were modeled using the finite volume method, while hydraulic fracture propagation and interaction with natural fractures were modeled using the variational phase-field method. Our findings underscore the importance of poroelastic and thermoelastic effects on fracture propagation in naturally fractured reservoirs. The results of this study demonstrate that thermo-hydromechanical processes are crucial elements in simulating and optimizing an enhanced geothermal reservoir system. [ABSTRACT FROM AUTHOR]

Türkiye is located in the Mediterranean sector of the Alpine--Himalayan tectonic belt and is among the foremost seven countries in the world having an abundance of geothermal resources. The Central Anatolian Crystalline Complex (CACC) is one of the most important geothermal regions in Türkiye. This study aims to evaluate the geothermal system of CACC using the geological, structural, and hydrogeochemical properties that were obtained from previous studies. The present study investigated and evaluated the hydrogeochemical and isotopic properties of 762 water samples belonging to 45 different localities from 41 scientific studies. The result shows that CACC has different heat sources and different hydrogeochemical processes. Major element chemistry of the water reveals that the geothermal fluids are mostly of the Ca - Mg - HCO3, Na - Cl - HCO3, and Ca-Cl water types. Silica geothermometers suggest that the reservoir temperature ranges from 48 to 180 °C. Based on the δ18O - δD 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. [ABSTRACT FROM AUTHOR]

Identifying distributed strain sensing (DSS) patterns (or signatures), particularly those arising from different hydraulic fracture geometries, has gained significant attention and research effort. Recent works have generated a catalogue of signatures for planar hydraulic fractures in an elastic rock formation. Yet, in numerous cases (e.g., fault motion and some geothermal reservoir stimulation), the main mode of deformation is a shear on a fracture or a network of natural fractures (particularly during low pressure injection/circulation). However, the specific fiber signatures that result from such shear deformation have not been studied. In this study, we use a three-dimensional poroelastic hydraulic fracture simulator to capture the strain signatures resulting from the shear deformation of fractures in various orientations with respect to the monitoring well. Five key cases are examined: one where the fracture strike is perpendicular to the fiber, another with the strike running parallel to the fiber, a third case where the fracture strike is at 45 degrees to the fiber, a fourth case with a strike slip fault perpendicular to the fiber, and a fifth case where fiber is intersecting the fracture. Theoretically and physically meaningful results were obtained in all five cases, which completely differ from the heart-shaped signature of tensile fracture propagation. It was discovered that the strain pattern changes with the shear deformation direction with respect to the fiber. The model is then used to simulate the response of a fracture network at Utah FORGE to injection to assess whether a signature might be expected in response to the planned injection and circulation rates, and, if so, what strain pattern might be expected. The simulation confirms that a strain response can indeed be observed. More importantly, the fiber response that would be detected in the monitoring well would be a combination of strain signatures from dilation and shear deformation of differently oriented natural fractures. The results in this study provide useful insights on the application of fiber to other stimulation and/or circulation scenarios where shear deformation of a fracture or fracture network plays a major role.

Forecasting microseismic cloud shape as a proxy of stimulated rock volume may improve the design of an energy extraction system. The microseismic cloud created during hydraulic stimulation of geothermal reservoirs is known empirically to extend in the general direction of the maximum principal stress. However, this empirical relationship is often inconsistent with reported results, and the cloud growth process remains poorly understood. This study investigates microseismic cloud growth using data obtained from a hydraulic stimulation project in Basel, Switzerland, and explores its correlation with measured in situ stress. We applied principal component analysis to a time series of microseismicity for macroscopic characterization of microseismic cloud growth in two‐ and three‐dimensional space. The microseismic cloud, in addition to extending in the general direction of maximum principal stress, expanded in the direction of intermediate principal stress. The orientation of the least microseismic cloud growth was stable and almost identical to the minimum principal stress direction. Further, microseismic cloud shape ratios showed good agreement when compared with in situ stress magnitude ratios. The permeability tensor estimated from microseismicity also provided a good correlation in terms of direction and magnitude with the microseismic cloud growth. We show that in situ stress plays a dominant role by controlling the permeability of each existing fracture in the reservoir fracture system. Consequently, microseismic cloud growth can be scaled by in situ stress as a first‐order approximation if there is sufficient variation in the orientation of existing faults. Plain Language Summary: In the next generation of geothermal development, massive volumes of fluid are injected underground to either create a potential geothermal reservoir or enhance fluid flow. In that process, water migration can be tracked by small earthquakes that are rarely felt by humans. The region of small earthquakes can be regarded as an active geothermal reservoir. Knowing the reservoir's shape may improve the assessment and design of the energy extraction system. However, it is difficult to forecast the shape of a possible geothermal reservoir prior to fluid injection. This study investigated the temporal variations in the shape of the region of small earthquakes caused by fluid injection using the data from the geothermal project at Basel, Switzerland. We found that the region's shape is correlated to the local stress when the reservoir hosted various existing fractures. Thus, the geothermal reservoir shape can be forecasted in advance using knowledge of the regional stress, which may allow for better assessment of geothermal development. Key Points: Microseismic cloud shape is correlated to in situ stress ratio and the permeability tensorMicroseismic cloud growth is mainly controlled by in situ stress if there is sufficient variation in existing fracture orientationMicroseismic cloud shape can be forecasted macroscopically with the in situ stress ratio, for use in designing an energy extraction system [ABSTRACT FROM AUTHOR]

The development of clean, stable, and renewable hot dry rock geothermal energy is significant for alleviating the energy crisis, reducing environmental pollution, and improving human health. Enhanced geothermal system (EGS) is an advanced technology for developing geothermal energy efficiently by stimulating hot dry rock reservoir. This technology involves a complex hydro-thermal coupling process. A numerical approach is usually applied for analyzing heat extraction. In this paper, taking the geothermal reservoir of the Cooper basin in Australia as the research object, two models–a 3D zonal homogeneous permeability model and a heterogenious permeability model – are established based on the measured microseismic data of hydraulic fracturing. The latter one is inversed from microseismic data. The temperature field, seepage field and thermal performance of the reservoir are numerically studied, and their differences are compared and analyzed. The results show that with the same injection-production flow rate, fluid flows more quickly from the injection well to the production well while the temperature drops relatively more rapidly in the inhomogeneous model due to the dominant channel revealed by dense microseismic events near the wellbore. In the homogeneous model, the dominant flow channel is not as pronounced as in the previous model, and the temperature decreases more slowly. During the operation of the geothermal reservoir model, the change in heat recovery of the zonal homogeneous model is relatively stable, with a decline of 3.74%, and that of the inhomogeneous model is rather obvious, with a decline of 12.72%. Compared with the inhomogeneous model, a smaller temperature drop and a higher heat recovery exist in the homogeneous model. However, the permeability in the actual reservoir is uneven, and the simulated heat recovery of the zonal homogenization model is higher than the actual recovery. Therefore, the simulation results of the inhomogeneous model have more reference significance for practical engineering.

The geothermal resource has some advantages in energy-saving and emission-reduction. They include enormous reserves, high energy utilization efficiency, and low-cost operation and have played an important role in achieving the targets of carbon peak and carbon neutrality as the only renewable-clean energy on the planet that is not affected by weather and seasons. A systematical analysis of the developing courses and new progress of foreign countries’ middle-deep high-temperature geothermal resources was carried out to analyze the occurrence characteristics and development status of high-temperature geothermal resources. Furthermore, in comparison to the development of high-temperature geothermal resources in China, several suggestions which may provide a reference for the utilization of middle-deep geothermal resources in China are put forward for the actual demands. Conventional hydrothermal geothermal resources in China generally have mature power technology and significant potential. However, in comparison to the total resources, geothermal resources in China have a low development degree and significant development potential. Significantly, a variety of rare mineral resources are associated with geothermal fluids in China, but some issues exist in the development of the associated mineral resources in high-temperature geothermal fluids, such as unclear trace element distribution and development potential, resulting in a low level of resource development. Consequently, based on the potential evaluation of the associated mineral resources, comprehensive utilization of the associated mineral resources in deep geothermal fluids should be strengthened. High-temperature heat harm has become a significant problem as engineering construction in the high-temperature geothermal area has advanced, and the mining depth of mineral resources has gradually increased. The high-temperature heat harm not only has a serious impact on the health of workers but also impedes the construction process and raises costs. However, the resource attribute of high-temperature heat harm, on the other hand, has received little attention. Hence, there is relatively little research on the “resource utilization of heat energy” in deep mines and engineering construction, resulting in the waste of geothermal resources. Based on the potential evaluation of “heat harm resources,” more attention should be paid to the utilization of “heat harm resources” in engineering construction and “ore-thermal co-mining” in deep mines, as well as actively developing high-temperature heat harm resource utilization technology. In general, more attention should be paid to the development of China’s middle-depth geothermal resources. The development of an enhanced geothermal system based on conventional hydrothermal geothermal resources could be more effective. Furthermore, geothermal resource utilization should not be limited to geothermal fluid; associated mineral resources and high-temperature heat-harm resources have enormous resource potential as well.

The Middle East economy and life depend on imports, be it food, water, or energy, despite each country in the region having enormous energy resources to exploit and reduce dependency on countries outside the region and develop a socioeconomic model of regional cooperation and synergy. An estimated 371 TWh of electricity available from geothermal energy resources can be utilized by these countries to support basic needs and be free from food-energy-water imports by sharing their energy resources. The total amount of CO2 emissions from these countries is currently 945 x 106 kg, so these countries can further earn about 92 million euros from carbon savings, by using geothermal energy along this corridor. This amount can be utilized for augmenting the energy supply from geothermal sources. In this work, the available geothermal resources are evaluated, and suggestions are made how this energy can be best utilized for peaceful existence and cooperation in the region. [ABSTRACT FROM AUTHOR]

A comparative numerical analysis of the thermohydraulics of an enhanced geothermal system (EGS) project in Türkiye in Dikili area is presented. The fractured granodiorite is modelled as porous media, utilizing the numerically suggested data of other authors for the corresponding hydraulic characteristics. As the heat transmission fluid, two different mediums are alternatively considered. These are the more classical medium, water and the supercritical carbon dioxide (sCO2). Transient calculations are performed for a time period of twenty years, comparing the temporally developing results obtained for water and sCO2 with each other. Based on modeling parameters and assumptions, higher production temperatures are observed with sCO2, in comparison to water, implying an advantage for sCO2 usage as a working fluid in EGS. This is accompanied by the further advantage of a lower pressure drop for sCO2. On the other hand, the temperature advantage is relativized by the lower specific heat capacity of sCO2 causing a decrease in the production thermal power. In general, the present results are found to be encouraging for a further and more detailed analysis of the employment of sCO2 as working fluid in EGS. [ABSTRACT FROM AUTHOR]

Emergency general surgery (EGS) patients often present with anemia, in which preoperative transfusions are performed to mitigate anemia-associated risks. However, transfusions have also been noted to cause worse postoperative outcomes. This study examined how transfusion-associated outcomes vary at different levels of anemia. The American College of Surgeons National Surgical Quality Improvement Program database from 2005 to 2019 was used to identify patients who had undergone any of 12 major EGS procedures using Current Procedural Terminology codes. Patients were divided into two cohorts based on receipt of preoperative transfusion. Cohorts were subdivided into anemia severity levels and propensity score–matched within each using patient demographic and comorbidity variables. We analyzed 30-day postoperative outcomes, including morbidity, mortality, and return to odds ratio (OR), using univariate Chi-squared tests, Wilcoxon signed-rank tests, and multivariate logistic regression analyses. 595,407 EGS cases were identified. Receiving preoperative transfusion were 44.45% (n = 3058) of severely anemic, 10.94% (n = 9076) of moderately anemic, 1.34% (n = 1370) of mildly anemic, and 0.174% (n = 704) of no anemia patients. Transfusion resulted in an increased overall morbidity in the severe (OR 1.54), moderate (OR 1.50), mild (OR 1.71), and no anemia (OR 1.85) groups. Mortality increased in the moderate (OR 1.27), mild (OR 1.61), and no anemia (OR 1.76) subgroups. In severe anemia, transfusion status and mortality were not significantly associated. Transfusion is associated with higher morbidity and mortality rates in those with higher hematocrit levels, even after controlling for pre-existing comorbidities. A restrictive transfusion strategy should be considered to avoid risks for those with a hematocrit level more than 24%. [ABSTRACT FROM AUTHOR]

As one of the components in the enhanced geothermal system (EGS), fractures have an important influence on thermal extraction efficiency. Based on the Voronoi theory, a Voronoi fracture network is introduced in the multi-well injection enhanced geothermal system (EGS). A fully coupled thermo-hydro-mechanical model is established to simulate the heat extraction performance, and the accuracy of the model is verified through comparative analysis of analytical and numerical solutions. Furthermore, the temperature, heat extraction rate, thermal power, and injection pressure under the spatial–temporal evolution of the research model are investigated. The results show that fracture is the main flow channel of working fluid, and the thermal power of the Voronoi fracture model always maintains a high level. In addition, the thermal extraction performance of the model is compared by changing the relevant parameters of the model, such as well spacing, injection mass flow rate, and rock matrix permeability. For the Voronoi fracture model, the relative distance between injection and production wells and the injection mass flow has a positive effect on production temperature; it shows that when the well spacing is 400 m, the final production temperature is 549.68 K, which is 1.4 times that of 200 m, and the fracture permeability has little effect on the heat extraction performance. And as the injection temperature increases, it has little effect on production temperature and heat extraction ratio, while thermal power and injection pressure decrease with the increase in injection temperature. Overall, this study provides some reasonable suggestions about fracture networks and investigates sensitivity parameters which affect heat extraction efficiency. [ABSTRACT FROM AUTHOR]

Objective: Surgical intensive care unit (SICU) optimization is a critical factor impacting patient outcomes and resource utilization. SICUs operate using an open or closed model, where the surgeon or intensivist, respectively, manages critically-ill patients. In 2017, we adopted a closed-collaborative model. This study aimed to compare patient outcomes in the closed-collaborative model vs. the previous open model in a cohort of emergency general surgery (EGS) patients. Methods: A retrospective review of EGS SICU patients from August 2015 to July 2019 was performed. Patients were divided into ''Open'' and ''Closed'' cohorts before or after closed-collaborative model implementation on August 1, 2017. Demographic variables and clinical outcomes were analyzed. Results: We identified 434 patients (O:191; C:243). While no significant demographic differences were observed, there was a higher proportion of patients with qSOFA scores greater than 2 in the closed cohort. There were no differences regarding sepsis, cerebrovascular accident, myocardial infarction, venous thromboembolism, anemia, SICU length of stay (LOS), SICU costs, ventilation requirements, or ventilator duration; mortality rate was higher, but hospital LOS was shorter in the closed cohort. Conclusion: Overall, outcomes were not statistically different between the two models, despite sicker patients in the closed group, which we suspect accounts for the higher mortality in this group. We expect the decreased hospital LOS observed in the closed cohort improved bed management, patient flow, and ultimately led to institutional cost savings. Further investigation is warranted to examine SICU modeling effects in other surgical specialties and to evaluate potential hospital-level administrative benefits.

Geothermal energy provides a dispatchable source of carbon-free electricity that can balance the output of variable resources. However, geothermal provides just 3.7 gigawatts (GW _e ) ( ${\lt}$ 1%) of electricity in the United States today, mostly from hydrothermal resources that are geographically constrained. Enhanced geothermal systems (EGS), which extract heat from deep rock, could be applicable in more locations. However, baseline levels and potential trends in EGS costs have been insufficiently characterized by previous studies. Here, we assess geothermal penetration potential by using as baseline the latest available data on drilling costs from three costing models to create updated estimates of costs and performance. We input those estimates along with various scenarios of cost trends, emissions policies, and electricity demand into the regional energy deployment system (ReEDS) capacity expansion model to simulate electricity generation in the United States through 2050. The scarcity of hydrothermal resources limits deployments to no more than 18 GW _e across our scenarios. EGS is more costly than hydrothermal for now, but it has greater potential to scale nationwide. Thus, future deployments of EGS depend strongly on projected cost reductions and emissions policies. In scenarios with moderate ( ${\lt}$ 50%) reductions in costs by 2050, very little EGS is likely to be built, since wind and solar with storage provide lower-cost electricity. However, over 70% cost reductions from our updated baseline would make geothermal the least-cost carbon-free dispatchable resource. Under those cost trends, we project that 3 GW _e of EGS would be built by 2050 under existing policies, 11 GW _e with a 95% decarbonization policy, and 152 GW _e if full decarbonization of electricity is mandated. Most geothermal would likely first be built in western states with the steepest subsurface temperature gradients, although mandates for full decarbonization could drive it to be deployed in other states.

In this study, we analyze a deep hydraulic stimulation of a fracture zone that was conducted as part of the classical Fenton Hill Hot Dry Rock Program in the 1970s. At the time, it was suggested that a pre-existing fracture or multiple fractures within the fracture zone were jacked open by injection-induced increase in pressure. In this study, we analyze the same stimulation experiment, but investigate the possibility of an alternative mechanism of shear reactivation of pre-existing fractures. We conduct modeling that accounts for both jacking (or elastic-fracture opening) and shear-slip dilation and demonstrate that injection-induced shear reactivation (or hydroshearing) could have occurred simultaneously with seismic events of magnitudes lower than what can be felt by humans. In fact, simulations considering shear reactivation seem to better match observed fluid recovery after multiple injection cycles. Shear reactivation and shear dilation results in locked-open fractures, especially near the injection well that provides permeability of higher flow recovery. We then investigate the sensitivity of the proposed model by varying some of the critical parameters such as maximum aperture, dilation angle, as well as fracture density. Interestingly, none of the simulated cases resulted in a large event that could have been felt by humans, but did result in a cumulative seismic magnitude of less than 1 for each given stimulation step. These results suggest that a permanent irreversible permeability increase of several orders of magnitude can be obtained by hydroshearing in a “seismically” safe manner.

In this study, we analyze a deep hydraulic stimulation of a fracture zone that was conducted as part of the classical Fenton Hill Hot Dry Rock Program in the 1970s. At the time, it was suggested that a pre-existing fracture or multiple fractures within the fracture zone were jacked open by injection-induced increase in pressure. In this study, we analyze the same stimulation experiment, but investigate the possibility of an alternative mechanism of shear reactivation of pre-existing fractures. We conduct modeling that accounts for both jacking (or elastic-fracture opening) and shear-slip dilation and demonstrate that injection-induced shear reactivation (or hydroshearing) could have occurred simultaneously with seismic events of magnitudes lower than what can be felt by humans. In fact, simulations considering shear reactivation seem to better match observed fluid recovery after multiple injection cycles. Shear reactivation and shear dilation results in locked-open fractures, especially near the injection well that provides permeability of higher flow recovery. We then investigate the sensitivity of the proposed model by varying some of the critical parameters such as maximum aperture, dilation angle, as well as fracture density. Interestingly, none of the simulated cases resulted in a large event that could have been felt by humans, but did result in a cumulative seismic magnitude of less than 1 for each given stimulation step. These results suggest that a permanent irreversible permeability increase of several orders of magnitude can be obtained by hydroshearing in a “seismically” safe manner.

Enhanced geothermal system (EGS) is considered to be the most effective way to mine hot dry rock. A conceptual model of rock mass-fracture-rock mass was established to study the limitation of temperature, insulation and heat transfer on the temperature field of enhanced geothermal system and supercritical carbon dioxide enhanced geothermal system. The temperature field of the rock mass under three boundaries for 30 years has been obtained. Effects of fluid velocity, specific heat capacity and thermal conductivity of rock mass on the temperature field were studied. The results show that boundary conditions have a great influence on temperature change of the reservoir. Under three boundary conditions, flow velocity of the fluid has a great influence on the temperature. But thermal conductivity and specific heat capacity of the rock mass have a little influence on the temperature. Under the same boundary conditions, heat exchange effect of the supercritical carbon dioxide enhanced geothermal system is significantly better than that of the traditional enhanced geothermal system.

The purpose of this study is to examine the impact of green tax incentives such as investment tax credit and taxable income deductions related to the environmental sustainability and climate change which are becoming more popular in developing countries, whereas introducing green tax incentives related to the environment and climate change helps and meets the sustainability objectives of growth and development. For this purpose, we selected the top 100 listed companies on the Swedish stock market (SSM), Nasdaq Stockholm (SN), in order to better understand the real facts and figures of green tax environment. This study uses a longitudinal research design because sample observations vary across firms and over a short time and conducts probit and logistic regression to identify the beneficiaries of the tax incentives. The findings show that different firm-level characteristics significantly impact the probability of being an ITC beneficiary. [ABSTRACT FROM AUTHOR]

The stress state is an important parameter in terms of both earthquake nucleation and rupture. Here, a new stimulation technique is proposed for Enhanced Geothermal Systems (EGSs), which have previously been burdened with a number of high‐profile incidences of induced seismicity. This stimulation technique pre‐emptively alters, or preconditions, the stress state before injection. This preconditioning is achieved through fluid production, such that the zone of reduced pore pressure around the well results in a stress‐ and fracture‐energy‐ barrier to potential nucleating and/or propagating ruptures near the point of injection. Using an existing 1‐D linear slip‐weakening model, it is shown how this methodology has the potential to either suppress the nucleation of dynamic events or halt their propagation. In particular, reducing the pore pressure around the region to be stimulated such that the residual shear stress rises above the in‐situ value of shear stress results in ultimately stable nucleation regimes. These results hold for injection times which are small compared to the required time of production, but this methodology results in nucleation lengths, or, analogously, stimulated areas, which are orders of magnitudes larger than those safely achievable without preconditioning. An example of how this approach may be applied in the field as well as other possible methods to achieve a preconditioned reservoir are provided. Both laboratory‐scale and meso‐scale testing of preconditioning are recommended to further constrain the applicability of this methodology for the creation of EGSs. Plain Language Summary: Enhanced Geothermal Systems (EGSs) are attractive due to their ability to provide potentially ubiquitous clean baseload power. However, they have been shown to be capable of inducing damaging and dangerous earthquakes, especially during and just after reservoir stimulation, a process enhancing the ease of fluid flow and required if these systems are to achieve sufficient energy fluxes. Interestingly, the state of stress is an important parameter for earthquake behavior. As previous studies have shown that engineers are able to influence the state of stress through their operations, a methodology is proposed that pre‐emptively alters, or preconditions, the stress field through the reduction of pressure before stimulation. The possible effects of this type of preconditioning are investigated by building upon a previously developed numerical model. The results indicate that pore pressure preconditioning may be able to delay the nucleation of an earthquake or stop an already‐nucleated earthquake from growing larger, meaning it may allow for reservoir stimulation at a reduced risk of induced seismicity. This methodology can be performed with a single well but requires large production times when compared to the time of injection. Laboratory‐scale and medium‐scale testing of this methodology are recommended before its application to a real EGS. Key Points: A stimulation strategy for Enhanced Geothermal System, called pore pressure preconditioning, is introducedPreconditioning results in early time dynamic rupture being contained or suppressed by the induced stress‐ and fracture‐energy‐ barrierWith sufficient preconditioning, the slipping patch must surpass the induced pressure barrier before nucleating runaway dynamic rupture [ABSTRACT FROM AUTHOR]

In this study, microstructural evolution and its effects on mechanical properties across the thickness of a 120 mm Ni-Cr-Mo industrial ultra-heavy steel plate were quantitatively investigated by means of optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and electron back-scatter diffraction (EBSD). The results show that the martensite fraction is 65% at 10 mm and disappears at 40 mm, while granular bainite appears at 35 mm and climbs up to as high as 32% at 60 mm, with M-A constituents significantly coarsened. The strength drops with the gradual coarsening of the laths as well as decreased martensite fraction from the surface to the centre. The toughness is mainly affected by the block size and the morphology and quantity of M-A constituents. This study established a multivariate function between the microstructure and toughness (50% fibre area transition temperature, FATT50) with careful consideration of the influence of effective grain size (EGS) and M-A constituent size distribution. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Enhanced geothermal system (EGS) has been widely used to improve the production performance of geothermal reservoirs. Extracting the heat energy from geothermal reservoirs involves complex multi-physical process, referred to as the thermal–hydro–mechanical (T–H–M) coupling. To optimize the production schedule, numerical simulator is an important tool for EGS development. However, the numerical solution method based on FVM is rare in the literature. To address this gap, in this study, we derive the mathematical equations of fully coupled T–H–M model. Then, the solution method based on FVM is established. Next, the its accuracy is verified against two cases. Last, the proposed method is applied to an EGS model to simulate the heat extraction process. The evolutions of pressure, temperature, and fracture aperture are analyzed. The effects of controlling parameters of the extraction efficiency are discussed. Results indicate that increasing the injection rate will reduce the lifespan of EGS but accelerate the energy extraction. Increasing the injection temperature can promote the heat extraction to limited extent. Increasing the matrix permeability can significantly improve the extraction efficiency. Enlarging the fracture spacing can enlarge the heat recovery rate. In addition, reducing the fracture permeability can avoid thermal shortcut and improve the production performance. [ABSTRACT FROM AUTHOR]

In this paper, a new three-dimensional numerical model of geothermal extraction is established. The model utilizes spatial frequency to describe the heterogeneity of multiple physical parameters of the reservoir, and rough discrete fractures are constructed based on the Weierstrass-Mandelbrot fractal function. Finally, the study examines the impact of geological-engineering parameters on the heat extraction performance. The results show that after the fracture number increases to 7–9, the influence of fracture number on the low-temperature area gradually diminishes. With the increase in fracture width, the thermal breakthrough phenomenon becomes more pronounced, leading to a reduction in the heat extraction performance. The increase in fracture roughness coefficient can delay thermal breakthrough and improve heat extraction performance. When the fracture roughness coefficient increases from 1.6 to 11.6, the effective electric power increases by 19.44 %. The increase in injection rate intensifies thermal breakthrough, but it also enhances the heat extraction performance. When the injection rate increases from 60 l/s to 160 l/s, the effective electric power increases by 55.7 %. Increasing the injection temperature can delay thermal breakthrough and reduce the heat extraction performance. Abnormal high temperature reservoir (>0.03 K/m) has better heat extraction performance. [ABSTRACT FROM AUTHOR]

Abundant geothermal energy can be harvested from deep, low-permeability rocks using an enhanced geothermal system (EGS) that relies on an artificially created permeable fracture network through cold water injection. In this study, a two-way coupling technique for thermo-hydromechanical modeling was used to simulate hydraulic fracture propagation in an EGS. The transient heat and fluid flow in porous media were modeled using the finite volume method, while hydraulic fracture propagation and interaction with natural fractures were modeled using the variational phase-field method. Our findings underscore the importance of poroelastic and thermoelastic effects on fracture propagation in naturally fractured reservoirs. The results of this study demonstrate that thermo-hydromechanical processes are crucial elements in simulating and optimizing an enhanced geothermal reservoir system.

Glaucoma is the second leading cause of blindness in India. Despite advances in diagnosing and managing glaucoma, there is a lack of India-specific clinical guidelines on glaucoma. Ophthalmologists often refer to the European Glaucoma Society (EGS) and Asia-Pacific Glaucoma Society (APGS) guidelines. A group of glaucoma experts was convened to review the recently released EGS guideline (fifth edition) and the APGS guideline and explore their relevance to the Indian context. This review provides the salient features of EGS and APGS guidelines and their utility in Indian scenario. Glaucoma diagnosis should be based on visual acuity and refractive errors, slit-lamp examination, gonioscopy, tonometry, visual field (VF) testing, and clinical assessment of optic nerve head, retinal nerve fiber layer (RNFL), and macula. The intraocular pressure target must be individualized to the eye and revised at every visit. Prostaglandin analogues are the most effective medications and are recommended as the first choice in open-angle glaucoma (OAG). In patients with cataract and primary angle-closure glaucoma (PACG), phacoemulsification alone or combined phacoemulsification and glaucoma surgery are recommended. Trabeculectomy augmented with antifibrotic agents is recommended as the initial surgical treatment for OAG. Laser peripheral iridotomy and surgery in combination with medical treatment should be considered in high-risk individuals aged

MC transport parameters used are common to all egs++ applications. The effect of each transport parameter need to understand to optimize the simulation process. Therefore, the purpose of this study was to investigate the efficiency of egs++ simulation for different transport parameters in water phantom. This water phantom has built using slab. Collimated source defined 100 cm above the phantom. The simulation parameters such as the efficiency, statistical uncertainty, and accuracy of selecting transport parameters such as electron and photon cut-off energies, spin effects, atomic relaxations, and bound Compton scattering was investigated. The selection of ECUT and PCUT greatly affects the simulation time. The simulation time, efficiency and energy fractions have same value for varied ECUT except for 0.521 MeV. The energy fraction have been shifted but the simulation time and efficiency were same. Turning on spin effects in this simulation increases simulation time by 25%. The simulation time increases by about 15% when relaxations are turned on. The more accurate result of deposited energy using EGSnrc algorithm is about 30% slower than the less accurate PRESTA-I algorithm. Therefore, The optimization of transport parameters is needed in the simulation of egs++ to provide the best efficiency.

Porosity and permeability alteration due to the thermo-poro-elastic stress field disturbance from the cold fluid injection is a deciding factor for longer, more economic, and safer heat extraction from an enhanced geothermal system (EGS). In the Soultz-sous-Forêts geothermal system, faulted zones are the main flow paths, and the resulting porosity–permeability development over time due to stress reorientation is more sensitive in comparison with the regions without faulted zones. Available operational and field data are combined through a validated numerical simulation model to examine the mechanical impact on the pressure and temperature evolution. Results shows that near the injection wellbore zones, permeability and porosity values are strongly affected by stress field changes, and that permeability changes will affect the overall temperature and pressure of the system, demonstrating a fully coupled phenomenon. In some regions inside the faulted zones and close to injection wellbores, porosity doubles, whereas permeability may be enhanced up to 30 times. A sensitivity analysis is performed using two parameters which are not well discussed in the literature the for mechanical aspect, but the results in this study show that one of them impacts significantly on the porosity–permeability changes. Further experimental and field works on this parameter will help to model the heat extraction more precisely than before. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Turkey's primary energy source is fossil fuels, with a contribution of 55%. According to the International Energy Agency forecast, fossil fuels will continue to be the primary energy source for the next decade. The current CO2 emissions from fossil fuel‐based energy are 400 Mt. If the present energy usage trend continues, then the emissions will cross 500 Mt by 2030. However, Turkey has large scope to mitigate climate‐related issues and follow sustainable development agenda by increasing the share of geothermal energy as a primary energy source mix. The country established a strong geothermal energy program in 1984 by installing a 17 MWe geothermal power plant in Kızıldere and made tremendous progress in this field. Currently, the power generation has crossed 1665 MWe. Turkey has drawn a new road map to enhance its primary energy source mix by developing its radiogenic granites (Enhanced Geothermal Systems) for power generation and carbon dioxide capture programs. This is an emerging technology that is being recommended for Turkey. Currently, France, Australia, and the United Kingdom are surging ahead in implementing Enhanced Geothermal Systems (EGS), and France has established a pilot power plant using EGS and generating 10 MWe. The United Kingdom will be starting its 3 MWe power plant. The hydrothermal source, in combination with Enhanced Geothermal Systems, can contain the annual CO2 emissions to 500 Mt and reduce the per‐capita CO2 emissions to 4.5 tons annually. One of the greatest contributions to climate mitigation and sustainable development made by the geothermal industry is the sequestration of CO2 from the Kızıldere geothermal power plant for the manufacturıng of dry ice and use CO2 from the Tuzla geothermal power plant for minimizing scaling. This dry ice technology can be extended to the cement industry to capture 18 billion CO2 being emitted annually from clinker manufacturıng units. The dry ice will be useful in combating forest fires that are common in Turkey. The article discusses the new technological developments that Turkey is adopting to mitigate climate change and achieve sustainable development goals. [ABSTRACT FROM AUTHOR]

The paper deals with sustainability risks and their measurement in the conditions of small and medium-sized enterprises. SMEs in the context of sustainability have to find solutions to many complex issues because, in the transformation of enterprises towards sustainability, significant changes are needed in all business processes from product development through operational execution, logistics, and marketing, not excluding their management. To implement sustainable development, SMEs need to identify and quantify the risks that may affect their path towards sustainability. [ABSTRACT FROM AUTHOR]

Alternative sources of energy are the need of the hour and numerous technological innovations have been explored in recent years to facilitate the demand for sustainable energy sources. However, premature deployment without completing a comprehensive risk assessment and formulating mitigative measures can lead to catastrophes that could, in addition to financial losses and human fatalities, tarnish the public perception of an alternative energy source and hinder its proliferation. The Pohang Earthquake aptly demonstrates this phenomenon where Enhanced Geothermal System (EGS), a relatively new technology, led to a large scale induced seismic event. This paper explores the risk posed by fluid injection in the EGS process considering the induced seismic event at Pohang and includes a Bow-tie analysis that proposes preventive and recovery controls to keep the impact of such events to a minimum. The paper also examines the change in Korean public perception to geothermal energy following the induced earthquake. [ABSTRACT FROM AUTHOR]