Rock damage significantly affects coupled thermo-hydro-mechanical(THM)behavior in deep geothermal exploitation through changing thermal and hydrological properties of rocks.For this,a thermo-hydro-mechanical-damage(TH...Rock damage significantly affects coupled thermo-hydro-mechanical(THM)behavior in deep geothermal exploitation through changing thermal and hydrological properties of rocks.For this,a thermo-hydro-mechanical-damage(THMD)coupled model was developed to describe the coupling between rock damage and mechanical,fluid flow and heat transfer fields.The model considers rock heterogeneity,and incorporates the Mohr-Coulomb failure criterion and the maximum tensile stress criterion to evaluate shear and tensile damage.This numerical modeling methodology was first verified against analytical solutions and experimental results,and was then used to simulate the THMD coupling behavior in deep geothermal exploitation.A coupled numerical model was set up to simulate the geothermal fluids extraction and re-injection process in a reservoir at 1 km depth over a 7-year period.Rock damage was found to accelerate the propagation of cold fronts away from the injection well,and have a distinct effect on the performance of geothermal exploitation.When the rock damage was considered,the field injectivity increases by 8.4 times,the range of cooled regions increases by 18.6 times,and the vertical deformation changes by 1.2 times after 7 years of geothermal operations,compared to the scenario where it was not considered.Parametric studies have suggested that thermal contraction dominates the rock damage evolution,and that thermal-induced rock damage only occurs at a sufficiently large temperature difference between fluids injected and the reservoir.This work underscores the importance of accurately accounting for the damage effect on reservoir response during fluid injection activities that cause significant cooling of reservoir rocks.展开更多
The Yuncheng Basin,located in the southern part of the Fenwei Rift,North China,exhibits obvious crust thinning(Moho uplift of 6-8 km)and shallow Curie point depth(less than 18 km)and hence holds great potential for ge...The Yuncheng Basin,located in the southern part of the Fenwei Rift,North China,exhibits obvious crust thinning(Moho uplift of 6-8 km)and shallow Curie point depth(less than 18 km)and hence holds great potential for geothermal resources.However,geothermal exploration within the Yuncheng Basin typically faces significant challenges due to civil and industrial noise from dense populations and industrial activities.To address these challenges,both Controlled-Source Audio-frequency Magnetotellurics(CSAMT)and radon measurements were employed in Baozigou village to investigate the geothermal structures and identify potential geothermal targets.The CSAMT method effectively delineated the structure of the subsurface hydrothermal system,identifying the reservoir as Paleogene sandstones and Ordovician and Cambrian limestones at elevations ranging from−800 m to−2500 m.In particular,two concealed normal faults(F_(a)and F_(b))were newly revealed by the combination of CSAMT and radon profiling;these previously undetected faults,which exhibit different scales and opposing dips,are likely to be responsible for controlling the convection of thermal water within the Basin’s subsurface hydrothermal system.Moreover,this study developed a preliminary conceptual geothermal model for the Fen River Depression within the Yuncheng Basin,which encompasses geothermal heat sources,cap rocks,reservoirs,and fluid pathways,providing valuable insights for future geothermal exploration.In conjunction with the 3D geological model constructed from CSAMT resistivity structures beneath Baozigou village,test drilling is recommended in the northwestern region of the Baozigou area to intersect the potentially deep fractured carbonates that may contain temperature-elevated geothermal water.This study establishes a good set of guidelines for future geothermal exploration in this region,indicating that high-permeability faults in the central segments of the Fen River Depression are promising targets.展开更多
The geothermal resources in China are primarily found in its sedimentary basins,particularly in the large basins located in eastern China,which hold significant potential for geothermal energy development.The Songliao...The geothermal resources in China are primarily found in its sedimentary basins,particularly in the large basins located in eastern China,which hold significant potential for geothermal energy development.The Songliao,North China,and Zhangzhou basins are of special interest due to their considerable exploration depths,extensive development history,and high levels of research activity.This study focuses on the three basins to analyze their thermal reservoir characteristics in eastern China.Between 2017 and 2023,the research team carried out a comprehensive analysis involving deep boreholes that exceeded 4000 m in depth within these three basins.They meticulously created detailed physical profiles that captured essential characteristics such as porosity,permeability,and thermal properties,reaching down to the basement of each basin.The findings indicated that variations in thermal conductivity within shallow geotechnical layers significantly influence the redistribution of deep thermal energy in the upper layers of the earth.Furthermore,differences in physical properties notably affect heat transport processes.The research proposes distinct heat models tailored for each basin:For the Songliao Basin,a low-permeability model with homogeneous thermal properties is constructed;for the North China Basin,high permeability and thermal conductivity layers are highlighted;and a fracture network controlling water and heat is presented in the Zhangzhou Basin.To elucidate the thermal structure of these basins,the Curie surface and Moho surface were analyzed.The shallow Curie surface indicates ongoing intense thermal activity stemming from crustal heat sources,while a shallow Moho surface signifies historical vigorous mantle thermal activity associated with mantle source heat production.Furthermore,the research evaluates the geothermal resources and the potential for carbon emission reduction in these basins.Total volume of exploitable geothermal fluid is estimated to be 76.9×10^(9) m^(3)/a,corresponding to an annual renewable geothermal energy 1.47×10^(16)k J.The implementation of geothermal energy could lead to a reduction in annual CO_(2)emissions by nearly 2×10^(9) t,which constitutes about 17.4%of China’s national carbon emissions in 2022.This estimation provides invaluable theoretical insights and data support for geothermal exploration and sustainable development in eastern China.展开更多
Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer ...Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer potential of the fracture system in the target reservoir under mining activities remains in suspense.Hence,a coupled thermal-hydraulic-mechanical model was developed for the karst reservoir of Anju coal mine in China,considering non-isothermal convective heat transfer in fractures.This model examined the influence of stress redistribution due to different mining distances(MD)on the effective flow channel length/density and the high/low-aperture fracture distribution.The dynamic heat generation characteristics of the geothermal reservoir were evaluated.Key findings include:Mining-induced stress creates interlaced high-aperture and low-aperture fracture zones below the goaf.Within these interlaced zones,the combined effect of high-and low-aperture fractures restricts the effective flow channel length/density of the fracture network.This contraction of the flow field leads to a significant decline in production flow rate,which consequently reduces both the production flow rate and power as MD increases.This work represents the study of mining disturbances on geothermal production,providing a theoretical foundation for the co-development of coal and geothermal resources.展开更多
As mining depth increases,the temperature of the surrounding rock rises,drawing global attention to the potential for geothermal energy extraction from high-temperature water stored in collapsed rock masses-a prospect...As mining depth increases,the temperature of the surrounding rock rises,drawing global attention to the potential for geothermal energy extraction from high-temperature water stored in collapsed rock masses-a prospect that offers both promise and challenges.In response,this study proposes a functional backfilling method using mining solid waste to construct a high-porosity heat extraction space.The research integrates experiments,theoretical analysis,and simulations to examine the mechanical and permeability properties of solid waste backfill materials.It further aims to elucidate how flow velocity and initial temperature influence the evolution of the temperature field and the thermal performance.Results indicate that the backfill material achieves optimal mechanical strength with a glass fiber content of 10‰ and a length of 6 mm.Furthermore,the permeability of the solid waste backfill demonstrates a quadratic relationship with both axial and confining pressure.During the recovery stage,the temperature in the heat extraction space remains lower than that of the surrounding rock,with geothermal energy being extracted via convective heat transfer between the water medium and the rock.The amount of heat extracted shows a positive correlation with the flow velocity of the water medium and a negative correlation with its initial temperature.展开更多
Understanding the levels,causes,and sources of fluoride in groundwater is critical for public health,effective water resource management,and sustainable utilization.This study employs multivariate statistical methods,...Understanding the levels,causes,and sources of fluoride in groundwater is critical for public health,effective water resource management,and sustainable utilization.This study employs multivariate statistical methods,hazard quotient assessment,and geochemical analyses,such as mineral saturation index,ionic activities,and Gibbs diagrams,to investigate the hydrochemical characteristics,causes,and noncarcinogenic risks of fluoride in Red bed groundwater and geothermal water in the Guang'an area and neighboring regions.Approximately 9%of the Red bed groundwater samples contain fluoride concentrations exceeding 1 mg·L^(-1).The predominant water types identified are Cl-Na and HCO_(3)-Na,primarily influenced by evapotranspiration.Low-fluoride groundwater and high-fluoride geothermal water exhibit distinct hydrochemical types HCO_(3)-Ca and SO_(4)-Ca,respectively,which are mainly related to the weathering of carbonate,sulfate,and fluorite-containing rocks.Correlation analysis reveals that fluoride content in Red bed groundwater is positively associated with Na^(+),Cl^(-),SO_(4)^(2-),and TDS(r^(2)=0.45-0.64,p<0.01),while in geothermal water,it correlates strongly with pH,K^(+),Ca^(2+),and Mg^(2+)(r^(2)=0.52-0.80,p<0.05).Mineral saturation indices and ionic activities indicate that ion exchange processes and the dissolution of minerals such as carbonatite and fluorite are important sources of fluoride in groundwater.The enrichment of fluorine in the Red bed groundwater is linked to evaporation,cation exchange and dissolution of fluorite,caused by the lithologic characteristics of the red bed in this area.However,it exhibits minimal correlation with the geothermal water in the adjacent area.The noncarcinogenic health risk assessment indicates that 7%(n=5)of Red bed groundwater points exceed the fluoride safety limit for adults,while 12%(n=8)exceed the limit for children.These findings underscore the importance of avoiding highly fluoridated red bed groundwater as a direct drinking source and enhancing groundwater monitoring to mitigate health risks associated with elevated fluoride levels.展开更多
As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during min...As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during mining to decrease the min-ing workface temperature while also developing geothermal energy.This method is called the co-exploitation of mine and geothermal energy(CMGE).The geothermal development may precipitate the large-scale failure of the nearby fault zone during the mining process.However,the evolution of shear slide and shear failure of fault under geothermal production/rein-jection during mining is missing.Therefore,a fully-coupled hydraulic mechanism(HM)double-medium model for CMGE was developed based on the measured data of the Chensilou mine.A comparative analysis of the mechanical response of fault between CMGE and single mining was conducted.The disturbance of geothermal production pressure and reinjection pressure under mining on fault stability were respectively expounded.The results indicate that:(1)The disturbance of geo-thermal reinjection amplifies the disturbance of mining on fault stability.The amplified effect resulted in a normal stress drop of the fault,further leading to a substantial increase in shear slide distance,failure area,and cumulative seismic moment of fault compared with the single mining process.(2)As the distance of reinjection well to the fault decreases,the fault failure intensity increases.Setting the production well within the fault is advantageous for controlling fault stability under CMGE.(3)The essence of the combined disturbance of CMGE on the nearby fault is the overlay of tensile stress disturbance on the fault rock mass of the mining and geothermal reinjection.Though the geothermal reinjection causes a minor normal stress drop of fault,it can result in a more serious fault failure under CMGE.This paper supplies a significant gap in understanding thenearby faults failure under CMGE.展开更多
As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and ...As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and geothermal mining in mines to establish a thermos-hydraulic coupling numerical model for fractured formation.The study investigates the formation heat transfer behaviour,heat recovery performance and thermal economic benefits influenced during the life cycle.The results show that the accumulation of cold energy during the cold storage phase induces a decline in formation temperature.The heat recovery phase is determined by the extent of the initial cold domain,which contracts inward from the edge and decelerates the heat recovery rate gradually.With groundwater velocity increases,the thermal regulation efficiency gradually increases,the production temperature decreases,while the effective radius and thermal power increase first and then decrease.The injected volume and temperature significantly affect,with higher injection temperatures slowing thermal recovery,and the thermal regulation efficiency is more sensitive to changes in formation permeability and thermal conductivity.The heat extraction performance is positively correlated with all factors.The levelized cost of electricity is estimated at 0.1203$/(kW·h)during the cold storage.During the heat recovery,annual profit is primarily driven by cooling benefits.展开更多
Under the national"Dual Carbon"strategy,the development and utilization of stable and efficient renewable energy has become pivotal for energy structure transformation.Shandong Province hosts abundant geothe...Under the national"Dual Carbon"strategy,the development and utilization of stable and efficient renewable energy has become pivotal for energy structure transformation.Shandong Province hosts abundant geothermal resources with significant potential for large-scale exploitation.This paper systematically reviews the technological framework and application prospects of geothermal energy development in Shandong.First,the geological model of the geothermal system,centered on the"source-reservoir-caprock-conduit"framework,is elucidated.The characteristics of major thermal reservoirs,including the Neogene Guantao Formation,Paleogene Dongying Formation,and Cambrian-Ordovician strata,are analyzed in the context of Shandong’s geologic setting.Subsequently,advanced geophysical exploration methodologies—such as Magnetotelluric(MT),Controlled-Source Audio-Frequency Magnetotellurics(CSAMT),and Wide-Field Electromagnetic Method(WFEM)—are highlighted for their critical roles in precisely delineating thermal reservoirs and identifying heat-controlling structures,significantly improving exploration efficiency.In terms of utilization,this study examines diversified application models guided by the"cascade utilization"principle,emphasizing high-efficiency geothermal heating technologies(e.g.,geothermal heat pump systems)and power generation technologies(dry steam,fl ash steam,and binary cycle systems)tailored to resources of varying temperatures.The review demonstrates that technological innovations and mature application frameworks are driving the geothermal industry in Shandong toward high-quality development,providing robust support for regional energy security and low-carbon transition.展开更多
Xiong'an New Area boasts abundant geothermal resources,with widespread Jixianian geother-mal reservoirs serving as key targets for exploration and development.Zoning geothermal resources helps characterize their d...Xiong'an New Area boasts abundant geothermal resources,with widespread Jixianian geother-mal reservoirs serving as key targets for exploration and development.Zoning geothermal resources helps characterize their distribution and attributes,offering critical guidance for their sustainable exploitation and utilization.This study integrates data from drilling and production tests across 21 geothermal wells to analyze the Jixianian strata,including depth,thickness,temperature,single-well water yield,Groundwater Level Depth(GWD),and Total Dissolved Solids(TDS).Employing fuzzy mathematics,a zoning analysis was performed,yielding quantitative evaluation scores and delineating favorable zones for development.Key findings include:(1)Geothermal reservoirs in the Rongcheng and Niutuozhen uplifts exhibit shallow burial depths,substantial thicknesses,high productivity,and relatively low temperatures,making them highly suitable for large-scale geothermal exploitation;(2)Zones with high resource potential but uncertain conditions require further exploration to mitigate development risks;(3)Areas near the Rongcheng fault or Jixianian strata buried deeper than 4,000 m are recommended for deferred exploitation;(4)Comprehensive evaluation reveals that the Jixianian carbonate geothermal reservoirs in Xiong'an New Area manifest 168 geothermal resources of 5,370.31×10 J,geothermal fluid reserves of 101.17×10 m3,and recoverable fluid 4 reserves of 93.41×10 m3/d under balanced extraction and reinjection.Recoverable geothermal heat 164 amounts to 9.36×10 J/a,equivalent to 319.4×10 t/a of standard coal.This study provides valuable insights into the exploration and sustainable exploitation of deep geothermal reservoirs in Xiong'an New Area,enhancing resource utilization and contributing to the development of a green and sustainable Xiong'an New Area.展开更多
Geothermal exploration and development in North Africa have advanced significantly,driven by the region's rich geothermal resources and rising energy demand.The countries of Mauritania,Morocco,Algeria,Tunisia,Liby...Geothermal exploration and development in North Africa have advanced significantly,driven by the region's rich geothermal resources and rising energy demand.The countries of Mauritania,Morocco,Algeria,Tunisia,Libya,and Egypt are located near tectonic plate boundaries(African and Eurasian plates),giving them substantial geothermal potential.Various exploration activities,including geological surveys and geophysical studies,have been conducted to assess geothermal reservoirs and identify suitable development sites.This article reviews the progress made in geothermal exploration across the region,highlighting the key activities undertaken to evaluate geothermal resources.It also explores how government policies have played a critical role either in fostering or in freezing geothermal development.The different conducted assessments such as analyzing geological structures,hydrothermal systems,and subsurface temperatures lead to identify suitable sites for geothermal development and improve the understanding of subsurface conditions and ongoing projects.Today,some countries in North Africa are positioning themselves to become important players in the global geothermal energy landscape,and with continued investment and concerted efforts,the region has the potential to emerge as a prominent player in the global geothermal energy landscape.展开更多
To understand the applicability of high-temperature preformed particle gel(HT-PPG)for control of short-circuiting in enhanced geothermal systems(EGSs),core flooding experiments were conducted on fractured granite core...To understand the applicability of high-temperature preformed particle gel(HT-PPG)for control of short-circuiting in enhanced geothermal systems(EGSs),core flooding experiments were conducted on fractured granite cores under varying fracture widths,gel particle sizes and swelling ratios.Key parameters such as injection pressure,water breakthrough pressure,and residual resistance factor were measured to evaluate HT-PPG performance.The gel exhibited strong injectability,entering granite fractures at pressure gradients as low as 0.656 MPa/m;HT-PPG yields a superior sealing performance by significantly reducing the permeability;and dehydration occurs during HT-PPG propagation,with a dehydration ratio ranging from 4.71%to 11.36%.This study reveals that HT-PPG can be injected into geothermal formations with minimal pressure yet provides strong resistance to breakthrough once in place.This balance of injectability and sealing strength makes HT-PPG effective for addressing thermal short-circuiting in EGS reservoirs.展开更多
The development of machine learning and deep learning algorithms as well as the improvement ofhardware arithmetic power provide a rare opportunity for logging big data private cloud.With the deepeningof exploration an...The development of machine learning and deep learning algorithms as well as the improvement ofhardware arithmetic power provide a rare opportunity for logging big data private cloud.With the deepeningof exploration and development and the requirements of low-carbon development,the focus of exploration anddevelopment in the oil and gas industry is gradually shifting to the exploration and development of renewableenergy sources such as deep sea,deep earth and geothermal energy.The traditional petrophysical evaluation andinterpretation model has encountered great challenges in the face of new evaluation objects.To establish a distributedlogging big data private cloud platform with a unified learning model as the key,which realizes the distributed storageand processing of logging big data,and enables the learning of brand-new knowledge patterns from multi-attributedata in the large function space in the unified logging learning model integrating the expert knowledge and the datamodel,so as to solve the problem of geoengineering evaluation of geothermal fields.Based on the research ideaof“logging big data cloud platform---unified logging learning model---large function space---knowledge learning&discovery---application”,the theoretical foundation of unified learning model,cloud platform architecture,datastorage and learning algorithm,arithmetic power allocation and platform monitoring,platform stability,data security,etc.have been carried on analysis.The designed logging big data cloud platform realizes parallel distributed storageand processing of data and learning algorithms.New knowledge of geothermal evaluation is found in a large functionspace and applied to Geo-engineering evaluation of geothermal fields.The examples show its good application in theselection of logging series in geothermal fields,quality control of logging data,identification of complex lithologyin geothermal fields,evaluation of reservoir fluids,checking of associated helium,evaluation of cementing quality,evaluation of well-side fractures,and evaluation of geothermal water recharge under the remote logging module ofthe cloud platform.The first and second cementing surfaces of cemented wells in geothermal fields were evaluated,as well as the development of well-side distal fractures,fracture extension orientation.According to the well-sidefracture communication to form a good fluid pathway and large flow rate and long flow diameter of the thermalstorage fi ssure system,the design is conducive to the design of the recharge program of geothermal water.展开更多
Tai'an city,located in Shandong Province,China,is rich in geothermal resources,characterized by shallow burial,high water temperature,and abundant water supply,making them high value for exploitation.However,corro...Tai'an city,located in Shandong Province,China,is rich in geothermal resources,characterized by shallow burial,high water temperature,and abundant water supply,making them high value for exploitation.However,corrosion and scaling are main challenges that hinder the widespread application and effective utilization of geothermal energy.This study focuses on the typical geothermal fields in Tai'an,employing qualitative evaluations of the geochemical saturation index with temperature,combined with the corrosion coefficient,Ryznar index,boiler scale,and hard scale assessment,to predict corrosion and scaling trends in the geothermal water of the study area.The results show that the hydrochemical types of geothermal water in the study area are predominantly Na-Ca-SO^(4)and Ca-Na-SO_(4)-HCO_(3),with the water being weakly alkaline.Simulations of saturation index changes with temperature reveal that calcium carbonate scaling is dominant scaling type in the area,with no evidence of calcium sulfate scaling.In the Daiyue Qiaogou geothermal field,the water exhibited corrosive bubble water properties,moderate calcium carbonate scaling,and abundant boiler scaling.Feicheng Anjiazhuang geothermal field showed non-corrosive bubble water,moderate calcium carbonate scaling,and significant boiler scaling.The Daidao'an geothermal field presented corrosive semi-bubble water,moderate calcium carbonate scaling,and abundant boiler scaling.The findings provide a foundation for the efficient exploitation of geothermal resources in the region.Implementing anti-corrosion and scale prevention measures can significantly enhance the utilization of geothermal energy.展开更多
The karst geothermal reservoir in Xiong'an New Area is a representative example of an ancient buried hill geothermal system.However,published heat flow data are predominantly derived from the Cenozoic sedimentary ...The karst geothermal reservoir in Xiong'an New Area is a representative example of an ancient buried hill geothermal system.However,published heat flow data are predominantly derived from the Cenozoic sedimentary cap.Due to the limited depth of borehole exploration,heat flow measurements and analyses of the Archean crystalline base-ment in the study area are rare.Further investigation of the heat flow and temperature field characteristics within the Archean crystalline basement beneath the karst geothermal reservoir is necessary to understand the vertical distribution of heat flow and improve the geothermal genetic mechanism in the area.The D01 deep geothermal scientific drilling param-eter well was implemented in the Niutuozhen geothermal field of Xiong'an New Area.The well exposed the entire Gaoyuzhaung Formation karst geotheremal reservoir of the Jixian system and drilled 1,723.67 m into the Archean crys-talline basement,providing the necessary conditions for determining its heat flow.This study involved borehole tempera-ture measurements and thermophysical property testing of core samples from the D01 well to analyze the vertical distri-bution of heat flow.The findings revealed distinct segmentation in the geothermal gradient and rock thermophysical prop-erties.The geothermal reservoir of Gaoyuzhuang Formation is dominated by convection,with significant temperature inversions corresponding to karst fracture developments.In contrast,the Archean crystalline basement exhibits conduc-tive heat transfer.After 233 days of static equilibrium,the average geothermal gradients of the Gaoyuzhuang Formation and the Archean crystalline basement were determined to be 1.5°C/km and 18.3°C/km,respectively.These values adjusted to-0.8°C/km and 18.2°C/km after 551 days,with the longer static time curve approaching steady-state condi-tions.The average thermal conductivity of dolomite in Gaoyuzhuang Formation was measured as 4.37±0.82 W/(K·m),3 and that of Archean gneiss as 2.41±0.40 W/(K·m).The average radioactive heat generation rate were 0.30±0.32μW/m 3 for dolomite and 1.32±0.69μW/m for gneiss.Using the temperature curve after 551 days and thermal conductivity data,the Archean heat flow at the D01 well was calculated as(43.9±7.0)mW/m2,While the heat flow for the Neogene sedi-mentary cap was estimated at 88.6mW/m2.The heat flow of Neogene sedimentary caprock is significantly higher than 2 that of Archean crystalline basement at the D01 well,with an excess of 44.7 mW/m accounting for approximately 50%of the total heat flow in the Neogene sedimentary caprock.This is primarily attributed to lateral thermal convection within the high-porosity and high-permeability karst dolomite layer,and vertical thermal convection facilitated by the Niudong fault,which collectively contribute to the heat supply of the Neogene sedimentary caprock.Thermal convection in karst fissure and fault zone contribute approximately 50%of the heat flow in the Neogene sedimentary caprock.This study quantitatively revealed the vertical distribution of heat flow,providing empirical evidence for the genetic mechanism of the convection-conduction geothermal system in sedimentary basins.展开更多
This study investigates the feasibility and efficiency of geothermal energy for heating applications in Azerbaijan,with a specific focus on the Khachmaz region.Despite the country’s growing interest in sustainable en...This study investigates the feasibility and efficiency of geothermal energy for heating applications in Azerbaijan,with a specific focus on the Khachmaz region.Despite the country’s growing interest in sustainable energy,limited research has addressed the potential of ground-source heat pump(GSHP)systems under local climatic and soil conditions.To address this gap,the study employs GeoT*SOL simulation to evaluate systemperformance,incorporating site-specific parameters such as soil thermal conductivity,heating demand profiles,and regional weather data.The results show that the GSHP system achieves a maximum seasonal performance factor(SPF)of 5.62 and an average SPF of 4.86,indicating high operational efficiency.Additionally,the system provides an estimated annual CO_(2) emissions reduction of 1956 kg per household,highlighting its environmental benefits.Comparative analysis with conventional heating systems demonstrates considerable energy savings and emissions mitigation.The study identifies technical(e.g.,initial installation complexity)and economic(e.g.,high upfront costs)challenges to widespread implementation.Based on these insights,practical recommendations are proposed:policymakers are encouraged to support financial incentives and policy frameworks;urban planners should consider GSHP integration in regional heating plans;and engineers may adopt the simulation-based approach presented here for feasibility studies.This research contributes to the strategic advancement of renewable heating technologies in Azerbaijan.展开更多
Renewable energy resources,including geothermal,are crucial for sustainable environmental management and climate change mitigation,offering clean,reliable,and low-emission alternatives to fossil fuels that reduce gree...Renewable energy resources,including geothermal,are crucial for sustainable environmental management and climate change mitigation,offering clean,reliable,and low-emission alternatives to fossil fuels that reduce greenhouse gases and support ecological balance.In this study,geographic information system(GIS)predictive analysis was employed to explore geothermal prospects,promoting environmental sustainability by reducing the dependence on fossil energy resources.Spatial and statistical analysis including the attribute correlation analysis was used to evaluate the relationship between exploration data and geothermal energy resources represented by hot springs.The weighted sum model was then used to develop geothermal predictive maps while the accuracy of prediction was determined using the receiver operating characteristic/area under curve(ROC/AUC)analysis.Based on the attribute correlation analysis,exploration data relating to geological structures,host rock(Asu River Group)and sedimentary contacts were the most critical parameters for mapping geothermal resources.These parameters were characterized by a statistical association of 0.52,0.48,and 0.46 with the known geothermal occurrences.Spatial data integration reveals the central part of the study location as the most prospective zone for geothermal occurrences.This zone occupies 14.76%of the study location.Accuracy assessment using the ROC/AUC analysis suggests an efficiency of 81.5%for the weight sum model.GIS-based multi-criteria analysis improves the identification and evaluation of geothermal resources,leading to better decision-making.展开更多
Large basins are currently the global focus for geothermal development,with their hydrothermal system being controlled by a variety of factors,such as basement relief and fracture development.Donglihu is located at th...Large basins are currently the global focus for geothermal development,with their hydrothermal system being controlled by a variety of factors,such as basement relief and fracture development.Donglihu is located at the north of the Cangxian uplift in the North China Basin,the concentrated geothermal resource development zone in North China.This study systematically collects temperature logging data and long-term dynamic monitoring of water level and water quality as well as group well tracer test data carried out in this area in recent years,on the basis of which the hydrothermal controlling role of the deep hidden faults is systematically analyzed.The results show that the Cangdong fault communicates with different geothermal reservoirs in the shallow part and plays a specific role in the water-heat channel of the local area.As a result,the high-value area of the geothermal temperature gradient in the sedimentary layer of the Donglihu area is distributed around the Cangdong fault.The geothermal reservoir temperature of the Minghuazhen Formation within the influence of the fault is also significantly higher than the regional average,the hydraulic head of different geothermal reservoirs showing a consistent and synergistic trend.However,the water quality has been stable for many years without any apparent changes.This understanding has a particular significance for further deepening understanding of the geothermal genesis mechanism in sedimentary basins and guiding future geothermal exploration and development in the Donglihu area.展开更多
Purpose–This study is dedicated to systematically collating the distribution and utilization circumstances of geothermal resources in China.Moreover,it endeavors to formulate a comprehensive utilization scheme for ge...Purpose–This study is dedicated to systematically collating the distribution and utilization circumstances of geothermal resources in China.Moreover,it endeavors to formulate a comprehensive utilization scheme for geothermal resources during the construction and operation phases of the railway,thereby furnishing robust support and valuable reference for the holistic utilization of geothermal resources along the railway corridor.Design/methodology/approach–Through an in-depth analysis of the extant utilization of geothermal resources in China,it is discerned that the current utilization modalities are relatively rudimentary,bereft of rational planning and characterized by a low utilization rate.Concurrently,by integrating the practical requisites of railway construction and operation and conducting theoretical dissections,a comprehensive utilization plan for the construction and operation periods of railway is proffered.Findings–In light of the railway’s construction and operation characteristics,geothermal utilization models are categorized.During construction,comprehensive modalities include tunnel illumination power generation,construction area heating,tunnel antifreeze using shallow geothermal energy,tunnel pavement antifreeze and construction concrete maintenance.During operation,they comprise operation tunnel antifreeze,railway roadbed antifreeze,railway switch snow melting and deicing,geothermal power station establishment and railway hot spring health tourism planning.Originality/value–According to the characteristics and actual needs of railway construction and operation,it is of great significance to rationally utilize geothermal resources to promote the construction and operation of green railways.展开更多
The Xihu Depression,situated in the northeastern East China Sea Basin,represents the most significant natural gas-producing region in Eastern China.An insufficient understanding of reservoir heterogeneity in petroleum...The Xihu Depression,situated in the northeastern East China Sea Basin,represents the most significant natural gas-producing region in Eastern China.An insufficient understanding of reservoir heterogeneity in petroleum geological conditions―particularly within structural zones beyond the well-explored Pinghu Slope and Ningbo Anticline Belt―has hindered comprehensive hydrocarbon exploration across the sag.Critical knowledge gaps persist in characterizing the geothermal field,reconstructing thermal evolution histories,and constraining hydrocarbon generation phases.These limitations directly impede systematic evaluations of basin selection criteria,reservoir delineation,and their dynamic relationships within petroleum systems.This study analyzes the present geothermal gradient at a unified depth(4000-5000 m),the geothermal heat flow,the geothermal temperature at a unified depth(3000-6000 m),and the plan distribution characteristics of the geothermal temperatures of the exploration strata in the key study area in the Xihu Depression―the Western Slope and the Central Anticlinal Belt.The research in this study is based on present bottom-hole temperature measurements and temperature data for testing for oil,using a one-dimensional steady-state heat conduction equation and the Bullard method.The results indicate that the present geothermal gradient in the Xihu Depression,between a unified depth of 4000 m and 5000 m,ranges from 16.7◦C/km to 44.6℃/km,with an average of 30.6℃/km.The present geothermal heat flow is between 32.23 mW/m^(2)and 90.13 mW/m^(2),with an average of 52.03 mW/m^(2),indicating a typical cold basin.The formation temperature gradually increases with burial depth,from 3000 m to 6000 m.In the plane,the formation temperature gradually increases from the south to the north and from the edge of the depression to the center of the depression.The burial history and thermal evolution of the key plays of the Xihu Depression were reconstructed using apatite fission tracks and zircon U-Th/He data,combined with vitrinite reflectance,which revealed that the tectonic uplift that occurred during the Late Miocene Longjing Movement was a critical event in trap formation and hydrocarbon filling.The thermal-hydrocarbon generation history indicates that the Xihu Depression has mostly entered a high maturity stage,with gas condensate and condensate charging occurring between 16.4 Ma and 13 Ma and natural gas filling occurring at 5.3 Ma up to now.Hydrocarbon generation and expulsion in the Xihu Depression occurred early in the north and late in the south,with two stages in the north and one stage in the south.A study of the burial history-thermal history-hydrocarbon generation history based on the reconstruction of geothermal fields demonstrates the matching relationship between hydrocarbon generation,distribution,and accumulation in the Xihu Depression―an understanding that is vital for oil and gas exploration in the Xihu Depression.展开更多
基金funded by the Major National Science and Technology Project for Deep Earth of China(Grant No.2024ZD1003805)the National Natural Science Foundation of China(Grant Nos.52311530070 and 52004015).
文摘Rock damage significantly affects coupled thermo-hydro-mechanical(THM)behavior in deep geothermal exploitation through changing thermal and hydrological properties of rocks.For this,a thermo-hydro-mechanical-damage(THMD)coupled model was developed to describe the coupling between rock damage and mechanical,fluid flow and heat transfer fields.The model considers rock heterogeneity,and incorporates the Mohr-Coulomb failure criterion and the maximum tensile stress criterion to evaluate shear and tensile damage.This numerical modeling methodology was first verified against analytical solutions and experimental results,and was then used to simulate the THMD coupling behavior in deep geothermal exploitation.A coupled numerical model was set up to simulate the geothermal fluids extraction and re-injection process in a reservoir at 1 km depth over a 7-year period.Rock damage was found to accelerate the propagation of cold fronts away from the injection well,and have a distinct effect on the performance of geothermal exploitation.When the rock damage was considered,the field injectivity increases by 8.4 times,the range of cooled regions increases by 18.6 times,and the vertical deformation changes by 1.2 times after 7 years of geothermal operations,compared to the scenario where it was not considered.Parametric studies have suggested that thermal contraction dominates the rock damage evolution,and that thermal-induced rock damage only occurs at a sufficiently large temperature difference between fluids injected and the reservoir.This work underscores the importance of accurately accounting for the damage effect on reservoir response during fluid injection activities that cause significant cooling of reservoir rocks.
基金supported by the Shanxi Province Basic Research Program(No.20210302123374)Yuncheng University Doctoral Research Initiation Fund(No.YQ-2021008)+3 种基金Excellent doctors come to Shanxi to reward scientific research projects(No.QZX-2023020)Open Fund of State Key Laboratory of Precision Geodesy(No.SKLPG2025-1-1)Joint Open Fund of the Research Platforms of School of Computer Science,China University of Geosciences,Wuhan(No.PTLH2024-B-03)Hubei Provincial Natural Science Foundation Project(No.2025AFC095).
文摘The Yuncheng Basin,located in the southern part of the Fenwei Rift,North China,exhibits obvious crust thinning(Moho uplift of 6-8 km)and shallow Curie point depth(less than 18 km)and hence holds great potential for geothermal resources.However,geothermal exploration within the Yuncheng Basin typically faces significant challenges due to civil and industrial noise from dense populations and industrial activities.To address these challenges,both Controlled-Source Audio-frequency Magnetotellurics(CSAMT)and radon measurements were employed in Baozigou village to investigate the geothermal structures and identify potential geothermal targets.The CSAMT method effectively delineated the structure of the subsurface hydrothermal system,identifying the reservoir as Paleogene sandstones and Ordovician and Cambrian limestones at elevations ranging from−800 m to−2500 m.In particular,two concealed normal faults(F_(a)and F_(b))were newly revealed by the combination of CSAMT and radon profiling;these previously undetected faults,which exhibit different scales and opposing dips,are likely to be responsible for controlling the convection of thermal water within the Basin’s subsurface hydrothermal system.Moreover,this study developed a preliminary conceptual geothermal model for the Fen River Depression within the Yuncheng Basin,which encompasses geothermal heat sources,cap rocks,reservoirs,and fluid pathways,providing valuable insights for future geothermal exploration.In conjunction with the 3D geological model constructed from CSAMT resistivity structures beneath Baozigou village,test drilling is recommended in the northwestern region of the Baozigou area to intersect the potentially deep fractured carbonates that may contain temperature-elevated geothermal water.This study establishes a good set of guidelines for future geothermal exploration in this region,indicating that high-permeability faults in the central segments of the Fen River Depression are promising targets.
基金funded by the Basic Scientific Research of China Geological Academy(YK202305)National Key R&D Program of China(2019YFB1504101)+1 种基金National Natural Science Foundation of China(41602271)China Geological Survey(DD20160207 and DD20189112)。
文摘The geothermal resources in China are primarily found in its sedimentary basins,particularly in the large basins located in eastern China,which hold significant potential for geothermal energy development.The Songliao,North China,and Zhangzhou basins are of special interest due to their considerable exploration depths,extensive development history,and high levels of research activity.This study focuses on the three basins to analyze their thermal reservoir characteristics in eastern China.Between 2017 and 2023,the research team carried out a comprehensive analysis involving deep boreholes that exceeded 4000 m in depth within these three basins.They meticulously created detailed physical profiles that captured essential characteristics such as porosity,permeability,and thermal properties,reaching down to the basement of each basin.The findings indicated that variations in thermal conductivity within shallow geotechnical layers significantly influence the redistribution of deep thermal energy in the upper layers of the earth.Furthermore,differences in physical properties notably affect heat transport processes.The research proposes distinct heat models tailored for each basin:For the Songliao Basin,a low-permeability model with homogeneous thermal properties is constructed;for the North China Basin,high permeability and thermal conductivity layers are highlighted;and a fracture network controlling water and heat is presented in the Zhangzhou Basin.To elucidate the thermal structure of these basins,the Curie surface and Moho surface were analyzed.The shallow Curie surface indicates ongoing intense thermal activity stemming from crustal heat sources,while a shallow Moho surface signifies historical vigorous mantle thermal activity associated with mantle source heat production.Furthermore,the research evaluates the geothermal resources and the potential for carbon emission reduction in these basins.Total volume of exploitable geothermal fluid is estimated to be 76.9×10^(9) m^(3)/a,corresponding to an annual renewable geothermal energy 1.47×10^(16)k J.The implementation of geothermal energy could lead to a reduction in annual CO_(2)emissions by nearly 2×10^(9) t,which constitutes about 17.4%of China’s national carbon emissions in 2022.This estimation provides invaluable theoretical insights and data support for geothermal exploration and sustainable development in eastern China.
基金supported by the National Natural Science Foundation of China(Nos.U23B2091,52304104,and 52404157)the National Key R&D Program of China(No.2022YFC2905600)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(No.GZB20240825).
文摘Developing hydrothermal resources in highly conductive karst aquifers at deep mine floors is regarded as a potential approach to achieving the co-development of coal and geothermal resources.However,the heat transfer potential of the fracture system in the target reservoir under mining activities remains in suspense.Hence,a coupled thermal-hydraulic-mechanical model was developed for the karst reservoir of Anju coal mine in China,considering non-isothermal convective heat transfer in fractures.This model examined the influence of stress redistribution due to different mining distances(MD)on the effective flow channel length/density and the high/low-aperture fracture distribution.The dynamic heat generation characteristics of the geothermal reservoir were evaluated.Key findings include:Mining-induced stress creates interlaced high-aperture and low-aperture fracture zones below the goaf.Within these interlaced zones,the combined effect of high-and low-aperture fractures restricts the effective flow channel length/density of the fracture network.This contraction of the flow field leads to a significant decline in production flow rate,which consequently reduces both the production flow rate and power as MD increases.This work represents the study of mining disturbances on geothermal production,providing a theoretical foundation for the co-development of coal and geothermal resources.
基金funded by the Fundamental Research Funds for the Central Universities(No.XJ2025001701)。
文摘As mining depth increases,the temperature of the surrounding rock rises,drawing global attention to the potential for geothermal energy extraction from high-temperature water stored in collapsed rock masses-a prospect that offers both promise and challenges.In response,this study proposes a functional backfilling method using mining solid waste to construct a high-porosity heat extraction space.The research integrates experiments,theoretical analysis,and simulations to examine the mechanical and permeability properties of solid waste backfill materials.It further aims to elucidate how flow velocity and initial temperature influence the evolution of the temperature field and the thermal performance.Results indicate that the backfill material achieves optimal mechanical strength with a glass fiber content of 10‰ and a length of 6 mm.Furthermore,the permeability of the solid waste backfill demonstrates a quadratic relationship with both axial and confining pressure.During the recovery stage,the temperature in the heat extraction space remains lower than that of the surrounding rock,with geothermal energy being extracted via convective heat transfer between the water medium and the rock.The amount of heat extracted shows a positive correlation with the flow velocity of the water medium and a negative correlation with its initial temperature.
基金supported by the China Geological Survey Project(Nos.DD20220864 and DD20243077).
文摘Understanding the levels,causes,and sources of fluoride in groundwater is critical for public health,effective water resource management,and sustainable utilization.This study employs multivariate statistical methods,hazard quotient assessment,and geochemical analyses,such as mineral saturation index,ionic activities,and Gibbs diagrams,to investigate the hydrochemical characteristics,causes,and noncarcinogenic risks of fluoride in Red bed groundwater and geothermal water in the Guang'an area and neighboring regions.Approximately 9%of the Red bed groundwater samples contain fluoride concentrations exceeding 1 mg·L^(-1).The predominant water types identified are Cl-Na and HCO_(3)-Na,primarily influenced by evapotranspiration.Low-fluoride groundwater and high-fluoride geothermal water exhibit distinct hydrochemical types HCO_(3)-Ca and SO_(4)-Ca,respectively,which are mainly related to the weathering of carbonate,sulfate,and fluorite-containing rocks.Correlation analysis reveals that fluoride content in Red bed groundwater is positively associated with Na^(+),Cl^(-),SO_(4)^(2-),and TDS(r^(2)=0.45-0.64,p<0.01),while in geothermal water,it correlates strongly with pH,K^(+),Ca^(2+),and Mg^(2+)(r^(2)=0.52-0.80,p<0.05).Mineral saturation indices and ionic activities indicate that ion exchange processes and the dissolution of minerals such as carbonatite and fluorite are important sources of fluoride in groundwater.The enrichment of fluorine in the Red bed groundwater is linked to evaporation,cation exchange and dissolution of fluorite,caused by the lithologic characteristics of the red bed in this area.However,it exhibits minimal correlation with the geothermal water in the adjacent area.The noncarcinogenic health risk assessment indicates that 7%(n=5)of Red bed groundwater points exceed the fluoride safety limit for adults,while 12%(n=8)exceed the limit for children.These findings underscore the importance of avoiding highly fluoridated red bed groundwater as a direct drinking source and enhancing groundwater monitoring to mitigate health risks associated with elevated fluoride levels.
基金supported by the Key Project of the National Natural Science Foundation of China(U23B2091)the National Key R&D Program of China(2022YFC2905600)+1 种基金the Youth Project of the National Natural Science Foundation of China(52304104 and 52404157)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20240825).
文摘As the mine depth around the world increases,the temperature of the surrounding rock of the mining workface increases significantly.To control the heat hazards,the hot water in the mining floor is developed during mining to decrease the min-ing workface temperature while also developing geothermal energy.This method is called the co-exploitation of mine and geothermal energy(CMGE).The geothermal development may precipitate the large-scale failure of the nearby fault zone during the mining process.However,the evolution of shear slide and shear failure of fault under geothermal production/rein-jection during mining is missing.Therefore,a fully-coupled hydraulic mechanism(HM)double-medium model for CMGE was developed based on the measured data of the Chensilou mine.A comparative analysis of the mechanical response of fault between CMGE and single mining was conducted.The disturbance of geothermal production pressure and reinjection pressure under mining on fault stability were respectively expounded.The results indicate that:(1)The disturbance of geo-thermal reinjection amplifies the disturbance of mining on fault stability.The amplified effect resulted in a normal stress drop of the fault,further leading to a substantial increase in shear slide distance,failure area,and cumulative seismic moment of fault compared with the single mining process.(2)As the distance of reinjection well to the fault decreases,the fault failure intensity increases.Setting the production well within the fault is advantageous for controlling fault stability under CMGE.(3)The essence of the combined disturbance of CMGE on the nearby fault is the overlay of tensile stress disturbance on the fault rock mass of the mining and geothermal reinjection.Though the geothermal reinjection causes a minor normal stress drop of fault,it can result in a more serious fault failure under CMGE.This paper supplies a significant gap in understanding thenearby faults failure under CMGE.
基金financial support from the National Natural Science Foundation of China(Nos.52434006,52374151,and 51927808)。
文摘As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and geothermal mining in mines to establish a thermos-hydraulic coupling numerical model for fractured formation.The study investigates the formation heat transfer behaviour,heat recovery performance and thermal economic benefits influenced during the life cycle.The results show that the accumulation of cold energy during the cold storage phase induces a decline in formation temperature.The heat recovery phase is determined by the extent of the initial cold domain,which contracts inward from the edge and decelerates the heat recovery rate gradually.With groundwater velocity increases,the thermal regulation efficiency gradually increases,the production temperature decreases,while the effective radius and thermal power increase first and then decrease.The injected volume and temperature significantly affect,with higher injection temperatures slowing thermal recovery,and the thermal regulation efficiency is more sensitive to changes in formation permeability and thermal conductivity.The heat extraction performance is positively correlated with all factors.The levelized cost of electricity is estimated at 0.1203$/(kW·h)during the cold storage.During the heat recovery,annual profit is primarily driven by cooling benefits.
基金support from the foundation"Research on Key Technologies for Multi-source Energy Integration and Full-scenario Utilization of Zero-carbon Expressways under the Dual-Carbon Strategy"(NO.JS2024B004).
文摘Under the national"Dual Carbon"strategy,the development and utilization of stable and efficient renewable energy has become pivotal for energy structure transformation.Shandong Province hosts abundant geothermal resources with significant potential for large-scale exploitation.This paper systematically reviews the technological framework and application prospects of geothermal energy development in Shandong.First,the geological model of the geothermal system,centered on the"source-reservoir-caprock-conduit"framework,is elucidated.The characteristics of major thermal reservoirs,including the Neogene Guantao Formation,Paleogene Dongying Formation,and Cambrian-Ordovician strata,are analyzed in the context of Shandong’s geologic setting.Subsequently,advanced geophysical exploration methodologies—such as Magnetotelluric(MT),Controlled-Source Audio-Frequency Magnetotellurics(CSAMT),and Wide-Field Electromagnetic Method(WFEM)—are highlighted for their critical roles in precisely delineating thermal reservoirs and identifying heat-controlling structures,significantly improving exploration efficiency.In terms of utilization,this study examines diversified application models guided by the"cascade utilization"principle,emphasizing high-efficiency geothermal heating technologies(e.g.,geothermal heat pump systems)and power generation technologies(dry steam,fl ash steam,and binary cycle systems)tailored to resources of varying temperatures.The review demonstrates that technological innovations and mature application frameworks are driving the geothermal industry in Shandong toward high-quality development,providing robust support for regional energy security and low-carbon transition.
基金funded by the Study on enhanced heat transfer mechanism of low-permeability carbonate rocks under in-situ conditions under Grant number YK202305the National Natural Science Foundation of China under Grant number 42272350the Geothermal Survey Project of the China Geological Survey under Grant number DD20221676.
文摘Xiong'an New Area boasts abundant geothermal resources,with widespread Jixianian geother-mal reservoirs serving as key targets for exploration and development.Zoning geothermal resources helps characterize their distribution and attributes,offering critical guidance for their sustainable exploitation and utilization.This study integrates data from drilling and production tests across 21 geothermal wells to analyze the Jixianian strata,including depth,thickness,temperature,single-well water yield,Groundwater Level Depth(GWD),and Total Dissolved Solids(TDS).Employing fuzzy mathematics,a zoning analysis was performed,yielding quantitative evaluation scores and delineating favorable zones for development.Key findings include:(1)Geothermal reservoirs in the Rongcheng and Niutuozhen uplifts exhibit shallow burial depths,substantial thicknesses,high productivity,and relatively low temperatures,making them highly suitable for large-scale geothermal exploitation;(2)Zones with high resource potential but uncertain conditions require further exploration to mitigate development risks;(3)Areas near the Rongcheng fault or Jixianian strata buried deeper than 4,000 m are recommended for deferred exploitation;(4)Comprehensive evaluation reveals that the Jixianian carbonate geothermal reservoirs in Xiong'an New Area manifest 168 geothermal resources of 5,370.31×10 J,geothermal fluid reserves of 101.17×10 m3,and recoverable fluid 4 reserves of 93.41×10 m3/d under balanced extraction and reinjection.Recoverable geothermal heat 164 amounts to 9.36×10 J/a,equivalent to 319.4×10 t/a of standard coal.This study provides valuable insights into the exploration and sustainable exploitation of deep geothermal reservoirs in Xiong'an New Area,enhancing resource utilization and contributing to the development of a green and sustainable Xiong'an New Area.
文摘Geothermal exploration and development in North Africa have advanced significantly,driven by the region's rich geothermal resources and rising energy demand.The countries of Mauritania,Morocco,Algeria,Tunisia,Libya,and Egypt are located near tectonic plate boundaries(African and Eurasian plates),giving them substantial geothermal potential.Various exploration activities,including geological surveys and geophysical studies,have been conducted to assess geothermal reservoirs and identify suitable development sites.This article reviews the progress made in geothermal exploration across the region,highlighting the key activities undertaken to evaluate geothermal resources.It also explores how government policies have played a critical role either in fostering or in freezing geothermal development.The different conducted assessments such as analyzing geological structures,hydrothermal systems,and subsurface temperatures lead to identify suitable sites for geothermal development and improve the understanding of subsurface conditions and ongoing projects.Today,some countries in North Africa are positioning themselves to become important players in the global geothermal energy landscape,and with continued investment and concerted efforts,the region has the potential to emerge as a prominent player in the global geothermal energy landscape.
基金Supported by the U.S.Department of Energy’s Office of Energy Efficiency and Renewable Energy(EERE)under the Geothermal Technologies Office(GTO)“Innovative Methods to Control Hydraulic Properties of Enhanced Geothermal Systems”(DE-EE0009790).
文摘To understand the applicability of high-temperature preformed particle gel(HT-PPG)for control of short-circuiting in enhanced geothermal systems(EGSs),core flooding experiments were conducted on fractured granite cores under varying fracture widths,gel particle sizes and swelling ratios.Key parameters such as injection pressure,water breakthrough pressure,and residual resistance factor were measured to evaluate HT-PPG performance.The gel exhibited strong injectability,entering granite fractures at pressure gradients as low as 0.656 MPa/m;HT-PPG yields a superior sealing performance by significantly reducing the permeability;and dehydration occurs during HT-PPG propagation,with a dehydration ratio ranging from 4.71%to 11.36%.This study reveals that HT-PPG can be injected into geothermal formations with minimal pressure yet provides strong resistance to breakthrough once in place.This balance of injectability and sealing strength makes HT-PPG effective for addressing thermal short-circuiting in EGS reservoirs.
文摘The development of machine learning and deep learning algorithms as well as the improvement ofhardware arithmetic power provide a rare opportunity for logging big data private cloud.With the deepeningof exploration and development and the requirements of low-carbon development,the focus of exploration anddevelopment in the oil and gas industry is gradually shifting to the exploration and development of renewableenergy sources such as deep sea,deep earth and geothermal energy.The traditional petrophysical evaluation andinterpretation model has encountered great challenges in the face of new evaluation objects.To establish a distributedlogging big data private cloud platform with a unified learning model as the key,which realizes the distributed storageand processing of logging big data,and enables the learning of brand-new knowledge patterns from multi-attributedata in the large function space in the unified logging learning model integrating the expert knowledge and the datamodel,so as to solve the problem of geoengineering evaluation of geothermal fields.Based on the research ideaof“logging big data cloud platform---unified logging learning model---large function space---knowledge learning&discovery---application”,the theoretical foundation of unified learning model,cloud platform architecture,datastorage and learning algorithm,arithmetic power allocation and platform monitoring,platform stability,data security,etc.have been carried on analysis.The designed logging big data cloud platform realizes parallel distributed storageand processing of data and learning algorithms.New knowledge of geothermal evaluation is found in a large functionspace and applied to Geo-engineering evaluation of geothermal fields.The examples show its good application in theselection of logging series in geothermal fields,quality control of logging data,identification of complex lithologyin geothermal fields,evaluation of reservoir fluids,checking of associated helium,evaluation of cementing quality,evaluation of well-side fractures,and evaluation of geothermal water recharge under the remote logging module ofthe cloud platform.The first and second cementing surfaces of cemented wells in geothermal fields were evaluated,as well as the development of well-side distal fractures,fracture extension orientation.According to the well-sidefracture communication to form a good fluid pathway and large flow rate and long flow diameter of the thermalstorage fi ssure system,the design is conducive to the design of the recharge program of geothermal water.
基金funded by the Key R&D Program of Henan,China(No.241111321000)China Geological Survey Program(DD20221676).
文摘Tai'an city,located in Shandong Province,China,is rich in geothermal resources,characterized by shallow burial,high water temperature,and abundant water supply,making them high value for exploitation.However,corrosion and scaling are main challenges that hinder the widespread application and effective utilization of geothermal energy.This study focuses on the typical geothermal fields in Tai'an,employing qualitative evaluations of the geochemical saturation index with temperature,combined with the corrosion coefficient,Ryznar index,boiler scale,and hard scale assessment,to predict corrosion and scaling trends in the geothermal water of the study area.The results show that the hydrochemical types of geothermal water in the study area are predominantly Na-Ca-SO^(4)and Ca-Na-SO_(4)-HCO_(3),with the water being weakly alkaline.Simulations of saturation index changes with temperature reveal that calcium carbonate scaling is dominant scaling type in the area,with no evidence of calcium sulfate scaling.In the Daiyue Qiaogou geothermal field,the water exhibited corrosive bubble water properties,moderate calcium carbonate scaling,and abundant boiler scaling.Feicheng Anjiazhuang geothermal field showed non-corrosive bubble water,moderate calcium carbonate scaling,and significant boiler scaling.The Daidao'an geothermal field presented corrosive semi-bubble water,moderate calcium carbonate scaling,and abundant boiler scaling.The findings provide a foundation for the efficient exploitation of geothermal resources in the region.Implementing anti-corrosion and scale prevention measures can significantly enhance the utilization of geothermal energy.
基金funded by the National Key Research and Development Program(Grant Nos.2021YFB1507404 and 2018YFC0604305)the Project of China Geological Survey(Grant Nos.DD20221680,DD20189113,and DD20190127).
文摘The karst geothermal reservoir in Xiong'an New Area is a representative example of an ancient buried hill geothermal system.However,published heat flow data are predominantly derived from the Cenozoic sedimentary cap.Due to the limited depth of borehole exploration,heat flow measurements and analyses of the Archean crystalline base-ment in the study area are rare.Further investigation of the heat flow and temperature field characteristics within the Archean crystalline basement beneath the karst geothermal reservoir is necessary to understand the vertical distribution of heat flow and improve the geothermal genetic mechanism in the area.The D01 deep geothermal scientific drilling param-eter well was implemented in the Niutuozhen geothermal field of Xiong'an New Area.The well exposed the entire Gaoyuzhaung Formation karst geotheremal reservoir of the Jixian system and drilled 1,723.67 m into the Archean crys-talline basement,providing the necessary conditions for determining its heat flow.This study involved borehole tempera-ture measurements and thermophysical property testing of core samples from the D01 well to analyze the vertical distri-bution of heat flow.The findings revealed distinct segmentation in the geothermal gradient and rock thermophysical prop-erties.The geothermal reservoir of Gaoyuzhuang Formation is dominated by convection,with significant temperature inversions corresponding to karst fracture developments.In contrast,the Archean crystalline basement exhibits conduc-tive heat transfer.After 233 days of static equilibrium,the average geothermal gradients of the Gaoyuzhuang Formation and the Archean crystalline basement were determined to be 1.5°C/km and 18.3°C/km,respectively.These values adjusted to-0.8°C/km and 18.2°C/km after 551 days,with the longer static time curve approaching steady-state condi-tions.The average thermal conductivity of dolomite in Gaoyuzhuang Formation was measured as 4.37±0.82 W/(K·m),3 and that of Archean gneiss as 2.41±0.40 W/(K·m).The average radioactive heat generation rate were 0.30±0.32μW/m 3 for dolomite and 1.32±0.69μW/m for gneiss.Using the temperature curve after 551 days and thermal conductivity data,the Archean heat flow at the D01 well was calculated as(43.9±7.0)mW/m2,While the heat flow for the Neogene sedi-mentary cap was estimated at 88.6mW/m2.The heat flow of Neogene sedimentary caprock is significantly higher than 2 that of Archean crystalline basement at the D01 well,with an excess of 44.7 mW/m accounting for approximately 50%of the total heat flow in the Neogene sedimentary caprock.This is primarily attributed to lateral thermal convection within the high-porosity and high-permeability karst dolomite layer,and vertical thermal convection facilitated by the Niudong fault,which collectively contribute to the heat supply of the Neogene sedimentary caprock.Thermal convection in karst fissure and fault zone contribute approximately 50%of the heat flow in the Neogene sedimentary caprock.This study quantitatively revealed the vertical distribution of heat flow,providing empirical evidence for the genetic mechanism of the convection-conduction geothermal system in sedimentary basins.
文摘This study investigates the feasibility and efficiency of geothermal energy for heating applications in Azerbaijan,with a specific focus on the Khachmaz region.Despite the country’s growing interest in sustainable energy,limited research has addressed the potential of ground-source heat pump(GSHP)systems under local climatic and soil conditions.To address this gap,the study employs GeoT*SOL simulation to evaluate systemperformance,incorporating site-specific parameters such as soil thermal conductivity,heating demand profiles,and regional weather data.The results show that the GSHP system achieves a maximum seasonal performance factor(SPF)of 5.62 and an average SPF of 4.86,indicating high operational efficiency.Additionally,the system provides an estimated annual CO_(2) emissions reduction of 1956 kg per household,highlighting its environmental benefits.Comparative analysis with conventional heating systems demonstrates considerable energy savings and emissions mitigation.The study identifies technical(e.g.,initial installation complexity)and economic(e.g.,high upfront costs)challenges to widespread implementation.Based on these insights,practical recommendations are proposed:policymakers are encouraged to support financial incentives and policy frameworks;urban planners should consider GSHP integration in regional heating plans;and engineers may adopt the simulation-based approach presented here for feasibility studies.This research contributes to the strategic advancement of renewable heating technologies in Azerbaijan.
文摘Renewable energy resources,including geothermal,are crucial for sustainable environmental management and climate change mitigation,offering clean,reliable,and low-emission alternatives to fossil fuels that reduce greenhouse gases and support ecological balance.In this study,geographic information system(GIS)predictive analysis was employed to explore geothermal prospects,promoting environmental sustainability by reducing the dependence on fossil energy resources.Spatial and statistical analysis including the attribute correlation analysis was used to evaluate the relationship between exploration data and geothermal energy resources represented by hot springs.The weighted sum model was then used to develop geothermal predictive maps while the accuracy of prediction was determined using the receiver operating characteristic/area under curve(ROC/AUC)analysis.Based on the attribute correlation analysis,exploration data relating to geological structures,host rock(Asu River Group)and sedimentary contacts were the most critical parameters for mapping geothermal resources.These parameters were characterized by a statistical association of 0.52,0.48,and 0.46 with the known geothermal occurrences.Spatial data integration reveals the central part of the study location as the most prospective zone for geothermal occurrences.This zone occupies 14.76%of the study location.Accuracy assessment using the ROC/AUC analysis suggests an efficiency of 81.5%for the weight sum model.GIS-based multi-criteria analysis improves the identification and evaluation of geothermal resources,leading to better decision-making.
基金funded by Public Interest Monitoring Project(No.XCSD-2024-317)of the Tianjin Municipal Bureau of Planning and Natural Resources。
文摘Large basins are currently the global focus for geothermal development,with their hydrothermal system being controlled by a variety of factors,such as basement relief and fracture development.Donglihu is located at the north of the Cangxian uplift in the North China Basin,the concentrated geothermal resource development zone in North China.This study systematically collects temperature logging data and long-term dynamic monitoring of water level and water quality as well as group well tracer test data carried out in this area in recent years,on the basis of which the hydrothermal controlling role of the deep hidden faults is systematically analyzed.The results show that the Cangdong fault communicates with different geothermal reservoirs in the shallow part and plays a specific role in the water-heat channel of the local area.As a result,the high-value area of the geothermal temperature gradient in the sedimentary layer of the Donglihu area is distributed around the Cangdong fault.The geothermal reservoir temperature of the Minghuazhen Formation within the influence of the fault is also significantly higher than the regional average,the hydraulic head of different geothermal reservoirs showing a consistent and synergistic trend.However,the water quality has been stable for many years without any apparent changes.This understanding has a particular significance for further deepening understanding of the geothermal genesis mechanism in sedimentary basins and guiding future geothermal exploration and development in the Donglihu area.
文摘Purpose–This study is dedicated to systematically collating the distribution and utilization circumstances of geothermal resources in China.Moreover,it endeavors to formulate a comprehensive utilization scheme for geothermal resources during the construction and operation phases of the railway,thereby furnishing robust support and valuable reference for the holistic utilization of geothermal resources along the railway corridor.Design/methodology/approach–Through an in-depth analysis of the extant utilization of geothermal resources in China,it is discerned that the current utilization modalities are relatively rudimentary,bereft of rational planning and characterized by a low utilization rate.Concurrently,by integrating the practical requisites of railway construction and operation and conducting theoretical dissections,a comprehensive utilization plan for the construction and operation periods of railway is proffered.Findings–In light of the railway’s construction and operation characteristics,geothermal utilization models are categorized.During construction,comprehensive modalities include tunnel illumination power generation,construction area heating,tunnel antifreeze using shallow geothermal energy,tunnel pavement antifreeze and construction concrete maintenance.During operation,they comprise operation tunnel antifreeze,railway roadbed antifreeze,railway switch snow melting and deicing,geothermal power station establishment and railway hot spring health tourism planning.Originality/value–According to the characteristics and actual needs of railway construction and operation,it is of great significance to rationally utilize geothermal resources to promote the construction and operation of green railways.
基金the National Natural Science Foundation of China(No.42430806)CNOOC(China)Co.,Ltd+1 种基金‘14th Five-Year'science and technology major project offshore deep/ultra-deep oil and gas exploration technology(KJGG2022-0402)‘14th Five-Year'national oil and gas resources evaluation CNOOC mining rights area and surrounding blank area oil and gas resources evaluation project(QGYQZYPJ2022-3).
文摘The Xihu Depression,situated in the northeastern East China Sea Basin,represents the most significant natural gas-producing region in Eastern China.An insufficient understanding of reservoir heterogeneity in petroleum geological conditions―particularly within structural zones beyond the well-explored Pinghu Slope and Ningbo Anticline Belt―has hindered comprehensive hydrocarbon exploration across the sag.Critical knowledge gaps persist in characterizing the geothermal field,reconstructing thermal evolution histories,and constraining hydrocarbon generation phases.These limitations directly impede systematic evaluations of basin selection criteria,reservoir delineation,and their dynamic relationships within petroleum systems.This study analyzes the present geothermal gradient at a unified depth(4000-5000 m),the geothermal heat flow,the geothermal temperature at a unified depth(3000-6000 m),and the plan distribution characteristics of the geothermal temperatures of the exploration strata in the key study area in the Xihu Depression―the Western Slope and the Central Anticlinal Belt.The research in this study is based on present bottom-hole temperature measurements and temperature data for testing for oil,using a one-dimensional steady-state heat conduction equation and the Bullard method.The results indicate that the present geothermal gradient in the Xihu Depression,between a unified depth of 4000 m and 5000 m,ranges from 16.7◦C/km to 44.6℃/km,with an average of 30.6℃/km.The present geothermal heat flow is between 32.23 mW/m^(2)and 90.13 mW/m^(2),with an average of 52.03 mW/m^(2),indicating a typical cold basin.The formation temperature gradually increases with burial depth,from 3000 m to 6000 m.In the plane,the formation temperature gradually increases from the south to the north and from the edge of the depression to the center of the depression.The burial history and thermal evolution of the key plays of the Xihu Depression were reconstructed using apatite fission tracks and zircon U-Th/He data,combined with vitrinite reflectance,which revealed that the tectonic uplift that occurred during the Late Miocene Longjing Movement was a critical event in trap formation and hydrocarbon filling.The thermal-hydrocarbon generation history indicates that the Xihu Depression has mostly entered a high maturity stage,with gas condensate and condensate charging occurring between 16.4 Ma and 13 Ma and natural gas filling occurring at 5.3 Ma up to now.Hydrocarbon generation and expulsion in the Xihu Depression occurred early in the north and late in the south,with two stages in the north and one stage in the south.A study of the burial history-thermal history-hydrocarbon generation history based on the reconstruction of geothermal fields demonstrates the matching relationship between hydrocarbon generation,distribution,and accumulation in the Xihu Depression―an understanding that is vital for oil and gas exploration in the Xihu Depression.
