The granitoids widely distributed in South China are characterized by multi-stage evolution via episodic intrusions,in a complex geodynamic setting.Since granites have high radioactive heat generation and excellent th...The granitoids widely distributed in South China are characterized by multi-stage evolution via episodic intrusions,in a complex geodynamic setting.Since granites have high radioactive heat generation and excellent thermal conductivity,a deep moderate-to high-temperature geothermal system can be formed in the presence of high-quality,fissured granite geothermal reservoirs and thermal insulation with appropriate cap rocks.The key to exploring deep geothermal resources is to identify high-quality fissured granite geothermal reservoirs of a certain scale in a thermal anomaly zone with high background heatflow values.To determine the controlling effects of the distribution and development characteristics of granite geothermal reservoirs on the generation and enrichment of deep geothermal resources,this study analyzed the characteristics of the geothermal reservoirs in the Huangshadong geothermal field in the Yuezhong Depression,Guangdong Province,and their controlling effects on the formation of geothermal resources.The results are as follows.The hydrothermal system in the Huangshadong geothermal field mainly distributed in the contact zones between magmatic plutons and surrounding rocks,is significantly controlled by faults,followed by neoid volcanic apparatus and magmatic activities.That is,the geothermal system therein is under joint control of structures and magmas.Moreover,fractured zones of neoid transtensional faults conduct the geothermal water in the hydrothermal system and control its shallow discharge.Therefore,the hydrothermal system in the study area is characterized by the control of transpressional tectonic zone and volcanic apparatus,and geothermal water conduction through fractured zones of transtensional faults.展开更多
We measure spatio-temporal variations of seismic velocity changes in Salton Sea Geothermal Field,California based on cross correlations of daily seismic traces recorded by a borehole seismic network from December 2007...We measure spatio-temporal variations of seismic velocity changes in Salton Sea Geothermal Field,California based on cross correlations of daily seismic traces recorded by a borehole seismic network from December 2007 to January 2014.We find clear co-seismic velocity reductions during the 2010 M 7.2 El Mayor–Cucapah,Mexico earthquake at~100 km further south,followed by long-term recoveries.The co-seismic reductions are larger with longer post-seismic recoveries in higher frequency bands,indicating that material damage and healing process mostly occurred in the shallow depth.In addition,the co-seismic velocity reductions are larger for ray paths outside the active fluid injection/extraction regions.The ray paths inside injection/extraction regions are associated with smaller co-seismic reductions,but subtle long-term velocity increases.We also build 3D transient water flow models based on monthly injection/extraction rates,and find correlations between several water flow parameters and co-seismic velocity reductions.We interpret the relative lack of co-seismic velocity changes within the geothermal region as unclogging of fracture network due to persistent fluid flows of geothermal production.The long-term velocity increase is likely associated with the ground water depletion and subsidence due to net production.展开更多
The Ganzi geothermal field is located in the Songpan-Ganzi orogenic belt in Sichuan Province.Many hot springs are exposed along the Yalahe valley in Ganzi geothermal field,which is a favorable area for hightemperature...The Ganzi geothermal field is located in the Songpan-Ganzi orogenic belt in Sichuan Province.Many hot springs are exposed along the Yalahe valley in Ganzi geothermal field,which is a favorable area for hightemperature geothermal resource exploration.However,the geological model of heat exchange,the regional structure controlling hydrothermal convection and the development model of geothermal reservoirs are still unclear.Therefore,further studies are necessary to meet the geothermal exploration requirements in the middle and deep strata of this geothermal field.In this study,a geological model of the geothermal system of Ganzi geothermal field is proposed.We are convinced that there exists a hydrothermal convection system in the Ganzi geothermal field,the heat transfer of which is accomplished through deep-rooted major faults.Therefore,the identification of deep-rooted major faults and the description of geothermal reservoirs are the research objects of the integrated geophysical methods.The main factors controlling the geothermal reservoirs in the deep-rooted Xianshuihe major fault and Yalahe fault zones are analyzed by using gravity,aeromagnetic,and electromagnetic methods and techniques.The analysis results of regional gravity and aeromagnetic anomalies show that the Xianshuihe major fault has produced obvious gravity and aeromagnetic anomalies on the surface,and thus the position and strike of this fault can be accurately predicted by inversion of the aeromagnetic anomalies.Geothermal reservoirs show low-resistivity anomalies in the electromagnetic profile.The inversion results of the controlled source audio-frequency magnetotelluric(CSAMT)data show that geothermal reservoirs are mainly developed along the Yalahe valley,and the west side of the valley is more favorable for geothermal exploration.This study is of guiding significance to the efficient exploitation and utilization of the Ganzi geothermal field.展开更多
The part of China,east of the Hu Huanyong Line,is commonly referred to as eastern China.It is characterized by a high population density and a well-developed economy;it also has huge energy demands.This study assesses...The part of China,east of the Hu Huanyong Line,is commonly referred to as eastern China.It is characterized by a high population density and a well-developed economy;it also has huge energy demands.This study assesses and promotes the large-scale development of geothermal resources in eastern China by analyzing deep geological structures,geothermal regimes,and typical geothermal systems.These analyses are based on data collected from geotectology,deep geophysics,geothermics,structural geology,and petrology.Determining the distribution patterns of intermediate-to-deep geothermal resources in the region helps develop prospects for their exploitation and utilization.Eastern China hosts superimposed layers of rocks from three major,global tectonic domainsd namely Paleo-Asian,Circum-Pacific,and Tethyan rocks.The structure of its crust and mantle exhibits a special flyover pattern,with basins and mountains as well as well-spaced uplifts and depressions alternatively on top.The lithosphere in Northeast China and North China is characterized by a thin,low density crust and mantle,whereas the lithosphere in South China has a thin,low density crust and a thick,high density mantle.The middle and upper crust contain geobodies with high conductivity and low velocity,with varying degrees of development that create favorable conditions for the formation and enrichment of geothermal resources.Moderate-to-high temperature geothermal resources are distributed in the MesozoiceCenozoic basins in eastern China,although moderate temperature geothermal resources with low abundance dominate.Porous sandstone reservoirs,karstified fractured-vuggy carbonate reservoirs,and fissured granite reservoirs are the main types of geothermal reservoirs in this region.Under the currently available technical conditions,the exploitation and utilization of geothermal resources in eastern China favor direct utilization over large-scale geothermal power generation.In Northeast China and North China,geothermal resources could be applied for large-scale geothermal heating purposes;geothermal heating could be applied during winter along parts of the Yangtze River while geothermal cooling would be more suitable for summer there;geothermal cooling could also be applied to much of South China.Geothermal resources can also be applied to high value-added industries,to aid agricultural practices,and for tourism.展开更多
The mechanism of magnetic nanoparticles(MNPs)affecting magnetic field uniformity is studied in this work.The spatial distribution of MNPs in liquid is simulated based on Monte Carlo method.The induced field of the sin...The mechanism of magnetic nanoparticles(MNPs)affecting magnetic field uniformity is studied in this work.The spatial distribution of MNPs in liquid is simulated based on Monte Carlo method.The induced field of the single MNP is combined with the magnetic field distribution of magnetofluid.In the simulation,magnetic field uniformity is described by a statistical distribution.As the chemical shift(CS)and full width at half maximum(FWHM)of magnetic resonance(MR)spectrum can reflect the uniformity of magnetic field,the simulation is verified by spectrum experiment.Simulation and measurement results prove that the CS and FWHM of the MR spectrum are basically positively correlated with the concentration of MNPs and negatively correlated with the temperature.The research results can explain how MNPs play a role in MR by affecting the uniform magnetic field,which is of great significance in improving the temperature measurement accuracy of magnetic nanothermometers and the spatial resolution of magnetic particle imaging.展开更多
The resource of the gas from coal and coal measures deep in Songliao Basin hasbeen drawing more and more attention to.It is necessary to find out the evolution regulari-ty of the geothermal field of the basin in addit...The resource of the gas from coal and coal measures deep in Songliao Basin hasbeen drawing more and more attention to.It is necessary to find out the evolution regulari-ty of the geothermal field of the basin in addition to a series of geological studies in orderto predict its resources because the ancient geothermal field of the basin is one of themain factors controlling the generation,evolution and disappearance of oil and gas.Inthe recent twenty years,it is generally believed that vitrinite reflectance is the best quanti-tative marker for the ancient geothermal field.In the present paper,a systematic studyof the vitrinite reflectance value of Songliao Basin and its influence factors is made by mul-tiple statistical analysis so as to reconstruct the evolutional process of the Moho and thecorresponding geothermal field.Then,an overall prediction is made of the vitrinitereflectance and the distribution of J<sub>3</sub>-K<sub>1</sub> fault basin group at the bottom of SongliaoBasin,which provides the evidence for the展开更多
The PPG PITT-CHAR XP flame retardant system has been used by COOEC to preventing the thermal softening of steel in the high temperature,whose degradation temperature is 80 ℃.To prevent damage to PPG PITT-CHAR XP fire...The PPG PITT-CHAR XP flame retardant system has been used by COOEC to preventing the thermal softening of steel in the high temperature,whose degradation temperature is 80 ℃.To prevent damage to PPG PITT-CHAR XP fire retardant paint from excessive heat during welding,it is necessary to get accurately reserved area near the welding joints prior to welding. For the foregoing reasons,the 80 ℃ temperature field distribution of thick plate multi-pass welding was analyzed with SYSWELD.The influence of welding groove form and time interval on welding temperature field was also analyzed. Results showed that the range of 80 ℃ welding temperature field increased with the increasing of weld layers at first and then it inclined to stable value. Interpass time setting was crucial to control the range of 80 ℃ welding temperature field. It was also found that double V groove had better thermal diffusivity than double-bevel groove.And double-bevel groove was better than single V groove.展开更多
There are many arguments on energy sources and main controlling factors of geothermal fields, so a systematic study on the distribution of ground temperature fields shall be necessary. In this paper the thermal conduc...There are many arguments on energy sources and main controlling factors of geothermal fields, so a systematic study on the distribution of ground temperature fields shall be necessary. In this paper the thermal conduction forward method of geothermal field is used to simulate cooling rate of abnormal heat sources and heat transfer of the paleo-uplift model. Combined with a large number of geothermal field exploration cases and oil exploration well temperature curves of domestic and foreign, the following conclusions are drawn:(1) According to the magmatic activity time, the magmatism activities are divided into two categories: Magma active areas(activity time < 500 000 years) and weak/magma inactive areas(activity time > 500 000 years). The latter has a fast cooling rate(the cooling time of the magma pocket buried around 10 km is less than 200 000 years) after it has intruded into the shallow layer and it has no direct contribution to modern geothermal fields;(2) China belongs to a weak/magma inactive area such as Tengchong region and Qinghai-Tibet region because the chronological data of these regions show that its magma activity time is more than 500 000 years;(3) The temperature of most geothermal fields can be obviously divided into three segments in the vertical direction: A high geothermal gradient segment(Segment H) at the surface, then a low geothermal gradient segment(Segment L) at a secondary depth, and finally a lower temperature segment(Segment D) at a deeper depth. The temperature isoline presents a mirror reflection relation on the temperature profile, indicating that geothermal field is dominated by heat conduction, rather than having an abnormally high temperature "heat source" to provide heat;(4) Near-surface(0-5 km) materials' lateral heterogeneity caused by tectonic movement shall probably be the main controlling factor of ground temperature fields.展开更多
Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the str...Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.展开更多
The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field dis...The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.展开更多
Fractures play a pivotal role in carbonate thermal storage systems,serving as primary hydraulic conductivity channels that significantly influence thermal breakthrough times and heat extraction efficiency in geotherma...Fractures play a pivotal role in carbonate thermal storage systems,serving as primary hydraulic conductivity channels that significantly influence thermal breakthrough times and heat extraction efficiency in geothermal-to-well systems.Their impact is critical for well placement and system life prediction.This paper focuses on a geothermal-to-well system within the carbonate reservoir of the Wumishan formation in the Rongcheng geothermal field,Xiong'an new area.It employs a combination of field tests and numerical simulations to determine the permeability of the reservoir and the evolution of fractures between wells.It also examines the influence of fracture width and roughness coefficient on the seepage and temperature fields under various injection scenarios and predicts thermal breakthrough times for production wells.The results show:Higher permeability is observed near well D16 compared to well D22 within the studied geothermal-to-well systems.Wider fractures between wells result in faster temperature decline in production wells.Lower injection flow rates lead to slower temperature reduction in injection wells.The use of roughness coefficients minimizes temperature variations in production wells.This study not only offers guidance for the development and utilization of the geothermal well system,but also contributes to a deeper understanding of the groundwater seepage and heat transfer process influenced by fractures.展开更多
Laboratory experiments have been conducted to study the flow field in a cyclone static micro-bubble flotation column. The method of Particle Image Velocimetry (PIV) was used. The flow field velocity distribution in bo...Laboratory experiments have been conducted to study the flow field in a cyclone static micro-bubble flotation column. The method of Particle Image Velocimetry (PIV) was used. The flow field velocity distribution in both cross section and longitudinal section within cyclonic zone was studied for different circulating volumes. The cross sectional vortex was also analyzed. The results show that in cross section as the circulating volume increases from 0.187 to 0.350 m 3 /h, the flow velocity ranges from 0 to 0.68 m/s. The flow field is mainly a non-vortex potential flow that forms a free vortex without outside energy input. In the cyclonic region the vortex deviates from the center of the flotation column because a single tangential opening introduces circulating fluid into the column. The tangential component of the velocity plays a defining role in the cross section. In the longitudinal section the velocity ranges from 0 to 0.08 m/s. The flow velocity increases as does the circulating volume. Advantageous mineral separation conditions arise from the combined effects of cyclonic flow in cross and longitudinal section.展开更多
An electron cyclotron resonance ion source model that uses a coaxial antenna to inject the RF power was simulated, and the corresponding hydrogen plasma densities of the ion source were calculated at different magneti...An electron cyclotron resonance ion source model that uses a coaxial antenna to inject the RF power was simulated, and the corresponding hydrogen plasma densities of the ion source were calculated at different magnetic field distributions via a fluid model. The results show that most of the microwave power is absorbed around the resonance surface near the antenna when the plasma density is below the cutoff density of 7.4 × 10^(16) m^(-3) for 2.45 GHz microwaves, and the simulation results also show that the plasma density is strongly influenced by the position and shape of the resonance surface, where a larger resonance surface would improve the plasma density.展开更多
Magnetic flux density around the weld area was used to reconstruct the current density distribution during resistance spot welding(RSW) of aluminum alloy according to inverse problem theory. A current-magnetic field m...Magnetic flux density around the weld area was used to reconstruct the current density distribution during resistance spot welding(RSW) of aluminum alloy according to inverse problem theory. A current-magnetic field model was established and the conjugate gradient method was used to solve this model. The results showed that the current density was low at the center of nugget while high on the edge of nugget. Moreover, the welding time of 30ms—60 ms is a key period for nucleation. The current density distribution can reflect whether the weld nugget is formed or splashed, therefore it has the potential to monitor the weld quality of RSW.展开更多
Under the dual influence of the mining disturbance of the previous working face and the advanced mining of the working face,the roadway is prone to large deformation,failure,and rockburst.Roadway stabilization has alw...Under the dual influence of the mining disturbance of the previous working face and the advanced mining of the working face,the roadway is prone to large deformation,failure,and rockburst.Roadway stabilization has always significantly influenced deep mining safety.In this article we used the research background of the large deformation failure roadway of Fa-er Coal Mine in Guizhou Province of China to propose two control methods:bolt-cable-mesh+concrete blocks+directional energy-gathering blasting(BCM-CBDE method)and 1st Generation-Negative Poisson’s Ratio(1G NPR)cable+directional energy-gathering blasting+dynamic pressure stage support(πgirder+single hydraulic prop+retractable U steel)(NPR-DEDP method).Meantime,we compared the validity of the large deformation failure control method in a deep gob-side roadway based on theoretical analysis,numerical simulations,and field experiments.The results show that directional energy-gathering blasting can weaken the pressure acting on the concrete blocks.However,the vertical stress of the surrounding rock of the roadway is still concentrated in the entity coal side and the concrete blocks,showing a’bimodal’distribution.BCM-CBDE method cannot effectively control the stability of the roadway.NPR-DEDP method removed the concrete blocks.It shows using the 1G NPR cable with periodic slipping-sticking characteristics can adapt to repeated mining disturbances.The peak value of the vertical stress of the roadway is reduced and transferred to the deep part of the surrounding rock mass,which promotes the collapse of the gangue in the goaf and fills the goaf.The pressure of the roadway roof is reduced,and the gob-side roadway is fundamentally protected.Meantime,the dynamic pressure stage support method withπgirder+single hydraulic prop+retractable U steel as the core effectively protects the roadway from dynamic pressure impact when the main roof is periodically broken.After the on-site implementation of NPR-DEDP method,the deformation of the roadway is reduced by more than 45%,and the deformation rate is reduced by more than 50%.展开更多
The dielectric barrier discharge(DBD)in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments.In this paper,the influence of the electric field dis...The dielectric barrier discharge(DBD)in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments.In this paper,the influence of the electric field distribution on the uniformity of DBD is theoretically analyzed and experimentally verified.It is found that a certain degree of uneven electric field distributions can control the development of electron avalanches and regulate their transition to streamers in the gap.The discharge phenomena and electrical characteristics prove that an enhanced Townsend discharge can be formed in atmospheric-pressure air with a curved-plate electrode.The spectral analysis further confirms that the gas temperature of the plasma produced by the curved-plate electrode is close to room temperature,which is beneficial for industrial applications.This paper presents the relationship between the electron avalanche transition and the formation of a uniform DBD,which can provide some references for the development and applications of the DBD in the future.展开更多
The Dongpu sag is located in the south of the Bohai Bay basin, China, and has abundant oil and gas reserves. To date, there has been no systematic documentation of its geothermal fields. This study measured the rock t...The Dongpu sag is located in the south of the Bohai Bay basin, China, and has abundant oil and gas reserves. To date, there has been no systematic documentation of its geothermal fields. This study measured the rock thermal conductivity of 324 cores from 47 wells, and calculated rock thermal conductivity for different formations. The geothermal gradient and terrestrial heat flow were calculated for 192 wells on basis of 892 formation-testing data from 523 wells. The results show that the Dongpu sag is characterized by a medium-temperature geothermal field between stable and active tectonic areas, with an average geothermal gradient of 32.0°C/km and terrestrial heat flow of 65.6 mW/m2. The geothermal fields in the Dongpu sag is significantly controlled by the Changyuan, Yellow River, and Lanliao basement faults. They developed in the Paleogene and the Dongying movement occurred at the Dongying Formation depositional period. The geothermal fields distribution has a similar characteristic to the tectonic framework of the Dongpu sag, namely two subsags, one uplift, one steep slope and one gentle slope. The oil and gas distribution is closely associated with the present geothermal fields. The work may provide constraints for reconstructing the thermal history and modeling source rock maturation evolution in the Dongpu sag.展开更多
Taking the Gaoshangpu-Liuzan geothermal field in the Nanpu sag of the Bohai Bay Basin as the research object, this paper discusses the geological conditions and potential of the geothermal resources of the Guantao For...Taking the Gaoshangpu-Liuzan geothermal field in the Nanpu sag of the Bohai Bay Basin as the research object, this paper discusses the geological conditions and potential of the geothermal resources of the Guantao Formation in the study area, and introduces the development practice of geothermal energy heating in Caofeidian. The average buried depth of the Guantao Formation is 1500–2500 m, the lithology is dominated by sandy conglomerate, and the average thickness of thermal reservoir is 120–300 m. The average porosity of thermal reservoir is 28%–35%, the permeability is(600–2000)×10^(-3) μm^(2), and the temperature of thermal reservoir is 70–110 ℃. The formation has total geothermal resources of 13.79×10^(18) J, equivalent to 4.70×10^(8) t of standard coal. Based on a large amount of seismic and drilling data from oil and gas exploration, this study carried out high quality target area selection, simulation of sandstone thermal reservoir, and production and injection in the same layer. The geothermal heating project with distributed production and injection well pattern covering an area of 230×10^(4) m^(2) was completed in the new district of Caofeidian in 2018. The project has been running steadily for two heating seasons, with an average annual saving of 6.06×10^(4) t of standard coal and a reduction of 15.87×10^(4) t of carbon dioxide, achieving good economic and social benefits. This project has proved that the Neogene sandstone geothermal reservoir in eastern China can achieve sustainable large-scale development by using the technology of "balanced production and injection in the same layer". It provides effective reference for the exploration and development of geothermal resource in oil and gas-bearing basins in eastern China.展开更多
The existence of thermal storage will correspondingly increase the temperature of surrounding strata and promote the continuous expansion,volatilization,upward migration,and loss of gas in the strata.As a result,a low...The existence of thermal storage will correspondingly increase the temperature of surrounding strata and promote the continuous expansion,volatilization,upward migration,and loss of gas in the strata.As a result,a low-concentration gas field will be formed in the strata above geothermal reservoirs.Geothermal reservoirs could in turn heat formation water and increase the solubility of soluble inorganic salts in the surrounding rocks and the total dissolved solids(TDS)content in the formation water.Since water can strongly wet and permeate strata,the dissolved inorganic salts migrate into upper strata along with water,giving rise to the formation of a high-concentration inorganic salt field in the strata above geothermal reservoirs.A higher geothermal reservoir temperature corresponds to more significant characteristics mentioned above.Therefore,a medium-to-high temperature geothermal system has a surface geochemical anomaly pattern of high inorganic salt concentrations and low gas concentrations(also referred to as the high-salt and low-gas pattern).This pattern is applied to the surface geochemical exploration of the two geothermal fields in Guangdong Province,i.e.,the Huangshadong geothermal field in Huizhou City and the Xinzhou geothermal field in Yangjiang City,revealing low-concentration gas fields above both.The application results also show that the exposed thermal spring water in both geological fields has higher concentration of dissolved inorganic salt than the surface water and nearby seawater,forming high-amplitude anomalies on the surface above geothermal reservoirs.These characteristics,as well as the measured temperature at known geothermal wells,verify the validity of the high-salt and low-gas pattern of medium-to-high temperature geothermal systems proposed in this study.Moreover,the high-salt and low-gas pattern proposed predicts three favorable medium-to-high temperature geothermal zones in the surface geochemical exploration of the Shiba Basin near the Huangshadong geothermal field.展开更多
Cap rocks with high thermal insulation are important for deep geothermal systems at a depth of 3000‒6000 m.Based on the deep geothermal geological conditions in the Fujian-Guangdong-Hainan area of South China,this stu...Cap rocks with high thermal insulation are important for deep geothermal systems at a depth of 3000‒6000 m.Based on the deep geothermal geological conditions in the Fujian-Guangdong-Hainan area of South China,this study established an ideal geological model of reservoir-cap rock assemblages and simulated the geothermal field distribution of cap rocks of different thicknesses and thermal conductivity.The simulation results show that the vertical geothermal temperature distribution in an uplifted area of a depression was present as inverted mirror reflections relative to the elevated area of the basement.Specifically,the isotherms above the elevated area are convex in shape,while those below the elevated area are concave.There is a temperature equilibrium line between the convex and concave isotherms.The heat flow moves from the depressed area to the uplifted area below the temperature equilibrium line and migrates in an opposite direction above the line.On this base,this study conducted the inversion of geothermal temperature fields in typical areas with thin,moderately thick,and thick cap rocks.The results indicate that,at the depth of 3000e6000 m,areas with thin cap rocks(igneous rock zone in the coastal area of Fujian)mainly host moderate-to low-temperature hydrothermal resources;areas with moderately thick cap rocks(Yuezhong Depression)have the geothermal temperature ranging between 100℃and 200℃and may develop moderate-to high-temperature hydrothermal resources and hot dry rocks(HDRs),with the former superimposing on the latter;and areas with thick cap rocks(onshore Beibuwan Basin)have a geothermal temperature of 120‒220℃,and contains mainly moderate-to high-temperature hydrothermal resources and HDRs.Therefore,it is recommended that the evaluation,exploitation,and utilization of deep geothermal resources be carried out according to the burial depth of the temperature equilibrium line and the specific demand for geothermal resources.展开更多
基金This work was funded by a number of scientific research programs,including subjects entitled Analysis and Geothermal Reservoir Stimulation Methods of Deep High-temperature Geothermal Systems in East China(No.:2021YFA0716004)Evaluation and Optimal Target Selection of Deep Geothermal Resources in the Igneous Province in South China(No.:2019YFC0604903)+1 种基金the National Key Research and Development Program of China,a project entitled Deep Geological Processes and Resource Effects of Basins(No.:U20B6001)the Joint Fund Program of the National Natural Science Foundation of China and Sinopec,and a project entitled Siting and Target Evaluation of Deep Geothermal Resources in Key Areas of Southeastern China(No.:P20041-1)of the Sinopec Science and Technology Research Program.
文摘The granitoids widely distributed in South China are characterized by multi-stage evolution via episodic intrusions,in a complex geodynamic setting.Since granites have high radioactive heat generation and excellent thermal conductivity,a deep moderate-to high-temperature geothermal system can be formed in the presence of high-quality,fissured granite geothermal reservoirs and thermal insulation with appropriate cap rocks.The key to exploring deep geothermal resources is to identify high-quality fissured granite geothermal reservoirs of a certain scale in a thermal anomaly zone with high background heatflow values.To determine the controlling effects of the distribution and development characteristics of granite geothermal reservoirs on the generation and enrichment of deep geothermal resources,this study analyzed the characteristics of the geothermal reservoirs in the Huangshadong geothermal field in the Yuezhong Depression,Guangdong Province,and their controlling effects on the formation of geothermal resources.The results are as follows.The hydrothermal system in the Huangshadong geothermal field mainly distributed in the contact zones between magmatic plutons and surrounding rocks,is significantly controlled by faults,followed by neoid volcanic apparatus and magmatic activities.That is,the geothermal system therein is under joint control of structures and magmas.Moreover,fractured zones of neoid transtensional faults conduct the geothermal water in the hydrothermal system and control its shallow discharge.Therefore,the hydrothermal system in the study area is characterized by the control of transpressional tectonic zone and volcanic apparatus,and geothermal water conduction through fractured zones of transtensional faults.
基金supported by the National Natural Science Foundation of China (project51478368,41272272)financial support from China Scholarship Council (CSC) for one-year research at Georgia Institute of Technology in 2016–2017+2 种基金supported by the Southern California Earthquake Center (SCEC Contribution No.12647Grant 17230)funded by NSF Cooperative Agreement EAR-1600087&USGS Cooperative Agreement G17AC00047
文摘We measure spatio-temporal variations of seismic velocity changes in Salton Sea Geothermal Field,California based on cross correlations of daily seismic traces recorded by a borehole seismic network from December 2007 to January 2014.We find clear co-seismic velocity reductions during the 2010 M 7.2 El Mayor–Cucapah,Mexico earthquake at~100 km further south,followed by long-term recoveries.The co-seismic reductions are larger with longer post-seismic recoveries in higher frequency bands,indicating that material damage and healing process mostly occurred in the shallow depth.In addition,the co-seismic velocity reductions are larger for ray paths outside the active fluid injection/extraction regions.The ray paths inside injection/extraction regions are associated with smaller co-seismic reductions,but subtle long-term velocity increases.We also build 3D transient water flow models based on monthly injection/extraction rates,and find correlations between several water flow parameters and co-seismic velocity reductions.We interpret the relative lack of co-seismic velocity changes within the geothermal region as unclogging of fracture network due to persistent fluid flows of geothermal production.The long-term velocity increase is likely associated with the ground water depletion and subsidence due to net production.
文摘The Ganzi geothermal field is located in the Songpan-Ganzi orogenic belt in Sichuan Province.Many hot springs are exposed along the Yalahe valley in Ganzi geothermal field,which is a favorable area for hightemperature geothermal resource exploration.However,the geological model of heat exchange,the regional structure controlling hydrothermal convection and the development model of geothermal reservoirs are still unclear.Therefore,further studies are necessary to meet the geothermal exploration requirements in the middle and deep strata of this geothermal field.In this study,a geological model of the geothermal system of Ganzi geothermal field is proposed.We are convinced that there exists a hydrothermal convection system in the Ganzi geothermal field,the heat transfer of which is accomplished through deep-rooted major faults.Therefore,the identification of deep-rooted major faults and the description of geothermal reservoirs are the research objects of the integrated geophysical methods.The main factors controlling the geothermal reservoirs in the deep-rooted Xianshuihe major fault and Yalahe fault zones are analyzed by using gravity,aeromagnetic,and electromagnetic methods and techniques.The analysis results of regional gravity and aeromagnetic anomalies show that the Xianshuihe major fault has produced obvious gravity and aeromagnetic anomalies on the surface,and thus the position and strike of this fault can be accurately predicted by inversion of the aeromagnetic anomalies.Geothermal reservoirs show low-resistivity anomalies in the electromagnetic profile.The inversion results of the controlled source audio-frequency magnetotelluric(CSAMT)data show that geothermal reservoirs are mainly developed along the Yalahe valley,and the west side of the valley is more favorable for geothermal exploration.This study is of guiding significance to the efficient exploitation and utilization of the Ganzi geothermal field.
基金This work was funded by a number of scientific research programs,including grants from the National Key Research and Development Program of China,titled‘Evaluation and Optimal Target Selection of Deep Geothermal Resources in the Igneous Province in South China’(Project No.2019YFC0604903)‘Analysis and Geothermal Reservoir Stimulation Methods of Deep High-temperature Geothermal Systems in East China’(Project No.2021YFA0716004)+2 种基金a grant from the Joint Fund Program of the National Natural Science Foundation of China and Sinopec,titled‘Deep Geological Processes and Resource Effects of Basins’(Project No.U20B6001)two grants from the Sinopec Science and Technology Research Program,titled'Single well evaluation of Well Fushenre 1 and study on the potential of deep geothermal resources in Hainan'(Project No.P23131)‘Siting and Target Evaluation of Deep Geothermal Resources in Key Areas of Southeastern China’(Project No.P20041-1).
文摘The part of China,east of the Hu Huanyong Line,is commonly referred to as eastern China.It is characterized by a high population density and a well-developed economy;it also has huge energy demands.This study assesses and promotes the large-scale development of geothermal resources in eastern China by analyzing deep geological structures,geothermal regimes,and typical geothermal systems.These analyses are based on data collected from geotectology,deep geophysics,geothermics,structural geology,and petrology.Determining the distribution patterns of intermediate-to-deep geothermal resources in the region helps develop prospects for their exploitation and utilization.Eastern China hosts superimposed layers of rocks from three major,global tectonic domainsd namely Paleo-Asian,Circum-Pacific,and Tethyan rocks.The structure of its crust and mantle exhibits a special flyover pattern,with basins and mountains as well as well-spaced uplifts and depressions alternatively on top.The lithosphere in Northeast China and North China is characterized by a thin,low density crust and mantle,whereas the lithosphere in South China has a thin,low density crust and a thick,high density mantle.The middle and upper crust contain geobodies with high conductivity and low velocity,with varying degrees of development that create favorable conditions for the formation and enrichment of geothermal resources.Moderate-to-high temperature geothermal resources are distributed in the MesozoiceCenozoic basins in eastern China,although moderate temperature geothermal resources with low abundance dominate.Porous sandstone reservoirs,karstified fractured-vuggy carbonate reservoirs,and fissured granite reservoirs are the main types of geothermal reservoirs in this region.Under the currently available technical conditions,the exploitation and utilization of geothermal resources in eastern China favor direct utilization over large-scale geothermal power generation.In Northeast China and North China,geothermal resources could be applied for large-scale geothermal heating purposes;geothermal heating could be applied during winter along parts of the Yangtze River while geothermal cooling would be more suitable for summer there;geothermal cooling could also be applied to much of South China.Geothermal resources can also be applied to high value-added industries,to aid agricultural practices,and for tourism.
文摘The mechanism of magnetic nanoparticles(MNPs)affecting magnetic field uniformity is studied in this work.The spatial distribution of MNPs in liquid is simulated based on Monte Carlo method.The induced field of the single MNP is combined with the magnetic field distribution of magnetofluid.In the simulation,magnetic field uniformity is described by a statistical distribution.As the chemical shift(CS)and full width at half maximum(FWHM)of magnetic resonance(MR)spectrum can reflect the uniformity of magnetic field,the simulation is verified by spectrum experiment.Simulation and measurement results prove that the CS and FWHM of the MR spectrum are basically positively correlated with the concentration of MNPs and negatively correlated with the temperature.The research results can explain how MNPs play a role in MR by affecting the uniform magnetic field,which is of great significance in improving the temperature measurement accuracy of magnetic nanothermometers and the spatial resolution of magnetic particle imaging.
文摘The resource of the gas from coal and coal measures deep in Songliao Basin hasbeen drawing more and more attention to.It is necessary to find out the evolution regulari-ty of the geothermal field of the basin in addition to a series of geological studies in orderto predict its resources because the ancient geothermal field of the basin is one of themain factors controlling the generation,evolution and disappearance of oil and gas.Inthe recent twenty years,it is generally believed that vitrinite reflectance is the best quanti-tative marker for the ancient geothermal field.In the present paper,a systematic studyof the vitrinite reflectance value of Songliao Basin and its influence factors is made by mul-tiple statistical analysis so as to reconstruct the evolutional process of the Moho and thecorresponding geothermal field.Then,an overall prediction is made of the vitrinitereflectance and the distribution of J<sub>3</sub>-K<sub>1</sub> fault basin group at the bottom of SongliaoBasin,which provides the evidence for the
基金Project(No.2016ZDJS05B03)supported by Shandong Key ResearchDevelopment Plan,Project(No.17CX06005&No.18CX06054A)supported by Department of Science&Technology of Shandong Province the Fundamental Research Funds for the Central Universities
文摘The PPG PITT-CHAR XP flame retardant system has been used by COOEC to preventing the thermal softening of steel in the high temperature,whose degradation temperature is 80 ℃.To prevent damage to PPG PITT-CHAR XP fire retardant paint from excessive heat during welding,it is necessary to get accurately reserved area near the welding joints prior to welding. For the foregoing reasons,the 80 ℃ temperature field distribution of thick plate multi-pass welding was analyzed with SYSWELD.The influence of welding groove form and time interval on welding temperature field was also analyzed. Results showed that the range of 80 ℃ welding temperature field increased with the increasing of weld layers at first and then it inclined to stable value. Interpass time setting was crucial to control the range of 80 ℃ welding temperature field. It was also found that double V groove had better thermal diffusivity than double-bevel groove.And double-bevel groove was better than single V groove.
基金jointly funded by the National Natural Science Foundation of China (41572314)the China Geological Survey Project "South Shale Gas Resource Potential Assessment" (No.20160181)
文摘There are many arguments on energy sources and main controlling factors of geothermal fields, so a systematic study on the distribution of ground temperature fields shall be necessary. In this paper the thermal conduction forward method of geothermal field is used to simulate cooling rate of abnormal heat sources and heat transfer of the paleo-uplift model. Combined with a large number of geothermal field exploration cases and oil exploration well temperature curves of domestic and foreign, the following conclusions are drawn:(1) According to the magmatic activity time, the magmatism activities are divided into two categories: Magma active areas(activity time < 500 000 years) and weak/magma inactive areas(activity time > 500 000 years). The latter has a fast cooling rate(the cooling time of the magma pocket buried around 10 km is less than 200 000 years) after it has intruded into the shallow layer and it has no direct contribution to modern geothermal fields;(2) China belongs to a weak/magma inactive area such as Tengchong region and Qinghai-Tibet region because the chronological data of these regions show that its magma activity time is more than 500 000 years;(3) The temperature of most geothermal fields can be obviously divided into three segments in the vertical direction: A high geothermal gradient segment(Segment H) at the surface, then a low geothermal gradient segment(Segment L) at a secondary depth, and finally a lower temperature segment(Segment D) at a deeper depth. The temperature isoline presents a mirror reflection relation on the temperature profile, indicating that geothermal field is dominated by heat conduction, rather than having an abnormally high temperature "heat source" to provide heat;(4) Near-surface(0-5 km) materials' lateral heterogeneity caused by tectonic movement shall probably be the main controlling factor of ground temperature fields.
基金supported by the Chongqing Natural Science Foundation(No.cstc2020jcyjmsxm X0904)the Chongqing Talent Plan(No.CQYC2020058263)+3 种基金the Chongqing Technology Innovation and Application Development Project(No.cstc2021ycjh-bgzxm0246)the China Postdoctoral Science Foundation(No.2021M693739)the Sichuan Science and Technology Program(No.2021YJ0539)the Natural Science foundation of Jiangsu higher education institutions of China(Grant No.19KJD170001)。
文摘Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.
基金Supported by National Key R&D Program of China(Grant No.2016YFF0203000)State Key Program of National Natural Science Foundation of China(Grant No.11834008)+5 种基金National Natural Science Foundation of China(Grant Nos.11774167,61571222)Fundamental research funds for the Central Universities(Grant No.020414380001)State Key Laboratory of Acoustics,Chinese Academy of Science(Grant No.SKLA201809)Key Laboratory of Underwater Acoustic Environment,Chinese Academy of Sciences(Grant No.SSHJ-KFKT-1701)AQSIQ technology R&D program(Grant No.2017QK125)Innovative Talents Program of Far East NDT New Technology&Application Forum
文摘The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.
基金supported by basic research project of Chinese Academy of Geological Sciences(No.YK202309).Special thanks are due to the reviewers and editors of this journal for their valuable suggestions and revisions of the manuscript.
文摘Fractures play a pivotal role in carbonate thermal storage systems,serving as primary hydraulic conductivity channels that significantly influence thermal breakthrough times and heat extraction efficiency in geothermal-to-well systems.Their impact is critical for well placement and system life prediction.This paper focuses on a geothermal-to-well system within the carbonate reservoir of the Wumishan formation in the Rongcheng geothermal field,Xiong'an new area.It employs a combination of field tests and numerical simulations to determine the permeability of the reservoir and the evolution of fractures between wells.It also examines the influence of fracture width and roughness coefficient on the seepage and temperature fields under various injection scenarios and predicts thermal breakthrough times for production wells.The results show:Higher permeability is observed near well D16 compared to well D22 within the studied geothermal-to-well systems.Wider fractures between wells result in faster temperature decline in production wells.Lower injection flow rates lead to slower temperature reduction in injection wells.The use of roughness coefficients minimizes temperature variations in production wells.This study not only offers guidance for the development and utilization of the geothermal well system,but also contributes to a deeper understanding of the groundwater seepage and heat transfer process influenced by fractures.
基金the State Key Basic Research Program of China (No. 2012CB214905)Key Program of National Natural Science Foundation of China (No. 500834006)the National Natural Science Foundation of China (No. 50974119) for financial support
文摘Laboratory experiments have been conducted to study the flow field in a cyclone static micro-bubble flotation column. The method of Particle Image Velocimetry (PIV) was used. The flow field velocity distribution in both cross section and longitudinal section within cyclonic zone was studied for different circulating volumes. The cross sectional vortex was also analyzed. The results show that in cross section as the circulating volume increases from 0.187 to 0.350 m 3 /h, the flow velocity ranges from 0 to 0.68 m/s. The flow field is mainly a non-vortex potential flow that forms a free vortex without outside energy input. In the cyclonic region the vortex deviates from the center of the flotation column because a single tangential opening introduces circulating fluid into the column. The tangential component of the velocity plays a defining role in the cross section. In the longitudinal section the velocity ranges from 0 to 0.08 m/s. The flow velocity increases as does the circulating volume. Advantageous mineral separation conditions arise from the combined effects of cyclonic flow in cross and longitudinal section.
文摘An electron cyclotron resonance ion source model that uses a coaxial antenna to inject the RF power was simulated, and the corresponding hydrogen plasma densities of the ion source were calculated at different magnetic field distributions via a fluid model. The results show that most of the microwave power is absorbed around the resonance surface near the antenna when the plasma density is below the cutoff density of 7.4 × 10^(16) m^(-3) for 2.45 GHz microwaves, and the simulation results also show that the plasma density is strongly influenced by the position and shape of the resonance surface, where a larger resonance surface would improve the plasma density.
基金Supported by the National Natural Science Foundation of China(No.51275342 and No.51275338)
文摘Magnetic flux density around the weld area was used to reconstruct the current density distribution during resistance spot welding(RSW) of aluminum alloy according to inverse problem theory. A current-magnetic field model was established and the conjugate gradient method was used to solve this model. The results showed that the current density was low at the center of nugget while high on the edge of nugget. Moreover, the welding time of 30ms—60 ms is a key period for nucleation. The current density distribution can reflect whether the weld nugget is formed or splashed, therefore it has the potential to monitor the weld quality of RSW.
基金funded by National Natural Science Foundation of China(52074300)Yueqi Young Scholars Project of China University of Mining and Technology Beijing(2602021RC84)+1 种基金China University of Mining and Technology(Beijing)fundamental scientific research funds—Doctoral students Top-notch Innovative Talents Fostering Funds(BBJ2023047)Guizhou Provincial Science and Technology Planning Project([2020]2Y030)。
文摘Under the dual influence of the mining disturbance of the previous working face and the advanced mining of the working face,the roadway is prone to large deformation,failure,and rockburst.Roadway stabilization has always significantly influenced deep mining safety.In this article we used the research background of the large deformation failure roadway of Fa-er Coal Mine in Guizhou Province of China to propose two control methods:bolt-cable-mesh+concrete blocks+directional energy-gathering blasting(BCM-CBDE method)and 1st Generation-Negative Poisson’s Ratio(1G NPR)cable+directional energy-gathering blasting+dynamic pressure stage support(πgirder+single hydraulic prop+retractable U steel)(NPR-DEDP method).Meantime,we compared the validity of the large deformation failure control method in a deep gob-side roadway based on theoretical analysis,numerical simulations,and field experiments.The results show that directional energy-gathering blasting can weaken the pressure acting on the concrete blocks.However,the vertical stress of the surrounding rock of the roadway is still concentrated in the entity coal side and the concrete blocks,showing a’bimodal’distribution.BCM-CBDE method cannot effectively control the stability of the roadway.NPR-DEDP method removed the concrete blocks.It shows using the 1G NPR cable with periodic slipping-sticking characteristics can adapt to repeated mining disturbances.The peak value of the vertical stress of the roadway is reduced and transferred to the deep part of the surrounding rock mass,which promotes the collapse of the gangue in the goaf and fills the goaf.The pressure of the roadway roof is reduced,and the gob-side roadway is fundamentally protected.Meantime,the dynamic pressure stage support method withπgirder+single hydraulic prop+retractable U steel as the core effectively protects the roadway from dynamic pressure impact when the main roof is periodically broken.After the on-site implementation of NPR-DEDP method,the deformation of the roadway is reduced by more than 45%,and the deformation rate is reduced by more than 50%.
基金supported by the Science and Technology Innovation Commission of Shenzhen(No.JCYJ20180507181858539)Shenzhen Science and Technology Program(No.KQTD20180412181422399)the National Key R&D Program of China(No.2019YFB2204500).
文摘The dielectric barrier discharge(DBD)in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments.In this paper,the influence of the electric field distribution on the uniformity of DBD is theoretically analyzed and experimentally verified.It is found that a certain degree of uneven electric field distributions can control the development of electron avalanches and regulate their transition to streamers in the gap.The discharge phenomena and electrical characteristics prove that an enhanced Townsend discharge can be formed in atmospheric-pressure air with a curved-plate electrode.The spectral analysis further confirms that the gas temperature of the plasma produced by the curved-plate electrode is close to room temperature,which is beneficial for industrial applications.This paper presents the relationship between the electron avalanche transition and the formation of a uniform DBD,which can provide some references for the development and applications of the DBD in the future.
基金granted by the Key Project of the National Natural Science Foundation of China (Grant Nos. 41125010, 91114202, 90914006)the key state science and technology projects (Grant No: 2011ZX05006-004)the National Basic Research Program of China (Grant No: 2011CB201100)
文摘The Dongpu sag is located in the south of the Bohai Bay basin, China, and has abundant oil and gas reserves. To date, there has been no systematic documentation of its geothermal fields. This study measured the rock thermal conductivity of 324 cores from 47 wells, and calculated rock thermal conductivity for different formations. The geothermal gradient and terrestrial heat flow were calculated for 192 wells on basis of 892 formation-testing data from 523 wells. The results show that the Dongpu sag is characterized by a medium-temperature geothermal field between stable and active tectonic areas, with an average geothermal gradient of 32.0°C/km and terrestrial heat flow of 65.6 mW/m2. The geothermal fields in the Dongpu sag is significantly controlled by the Changyuan, Yellow River, and Lanliao basement faults. They developed in the Paleogene and the Dongying movement occurred at the Dongying Formation depositional period. The geothermal fields distribution has a similar characteristic to the tectonic framework of the Dongpu sag, namely two subsags, one uplift, one steep slope and one gentle slope. The oil and gas distribution is closely associated with the present geothermal fields. The work may provide constraints for reconstructing the thermal history and modeling source rock maturation evolution in the Dongpu sag.
基金This study was supported and helped by Professor Yan Jiahong with China Petroleum Exploration and Development Research Institute,Yao Yanhua,Chief Geologist of the Hydrology Institute of PetroChina Liaohe Oilfield Company,and Dr.Kong Yanlong with the Institute of Geology and Geophysics,Chinese Academy of Sciences.
文摘Taking the Gaoshangpu-Liuzan geothermal field in the Nanpu sag of the Bohai Bay Basin as the research object, this paper discusses the geological conditions and potential of the geothermal resources of the Guantao Formation in the study area, and introduces the development practice of geothermal energy heating in Caofeidian. The average buried depth of the Guantao Formation is 1500–2500 m, the lithology is dominated by sandy conglomerate, and the average thickness of thermal reservoir is 120–300 m. The average porosity of thermal reservoir is 28%–35%, the permeability is(600–2000)×10^(-3) μm^(2), and the temperature of thermal reservoir is 70–110 ℃. The formation has total geothermal resources of 13.79×10^(18) J, equivalent to 4.70×10^(8) t of standard coal. Based on a large amount of seismic and drilling data from oil and gas exploration, this study carried out high quality target area selection, simulation of sandstone thermal reservoir, and production and injection in the same layer. The geothermal heating project with distributed production and injection well pattern covering an area of 230×10^(4) m^(2) was completed in the new district of Caofeidian in 2018. The project has been running steadily for two heating seasons, with an average annual saving of 6.06×10^(4) t of standard coal and a reduction of 15.87×10^(4) t of carbon dioxide, achieving good economic and social benefits. This project has proved that the Neogene sandstone geothermal reservoir in eastern China can achieve sustainable large-scale development by using the technology of "balanced production and injection in the same layer". It provides effective reference for the exploration and development of geothermal resource in oil and gas-bearing basins in eastern China.
基金This study was funded by the project entitled Exploration Technology for Deep Geothermal Resources in Igneous Rock Areas in South China(2019YFC0604902),Chinathe Ministry of Science and Technology of China,China+1 种基金the project entitled Research and Application of Key Technologies for Geophysical and Geochemical Exploration of Deep Geothermal Resources in Southeastern China(P20041-2),Chinathe Science and Technology Department of SINOPEC,China.
文摘The existence of thermal storage will correspondingly increase the temperature of surrounding strata and promote the continuous expansion,volatilization,upward migration,and loss of gas in the strata.As a result,a low-concentration gas field will be formed in the strata above geothermal reservoirs.Geothermal reservoirs could in turn heat formation water and increase the solubility of soluble inorganic salts in the surrounding rocks and the total dissolved solids(TDS)content in the formation water.Since water can strongly wet and permeate strata,the dissolved inorganic salts migrate into upper strata along with water,giving rise to the formation of a high-concentration inorganic salt field in the strata above geothermal reservoirs.A higher geothermal reservoir temperature corresponds to more significant characteristics mentioned above.Therefore,a medium-to-high temperature geothermal system has a surface geochemical anomaly pattern of high inorganic salt concentrations and low gas concentrations(also referred to as the high-salt and low-gas pattern).This pattern is applied to the surface geochemical exploration of the two geothermal fields in Guangdong Province,i.e.,the Huangshadong geothermal field in Huizhou City and the Xinzhou geothermal field in Yangjiang City,revealing low-concentration gas fields above both.The application results also show that the exposed thermal spring water in both geological fields has higher concentration of dissolved inorganic salt than the surface water and nearby seawater,forming high-amplitude anomalies on the surface above geothermal reservoirs.These characteristics,as well as the measured temperature at known geothermal wells,verify the validity of the high-salt and low-gas pattern of medium-to-high temperature geothermal systems proposed in this study.Moreover,the high-salt and low-gas pattern proposed predicts three favorable medium-to-high temperature geothermal zones in the surface geochemical exploration of the Shiba Basin near the Huangshadong geothermal field.
基金This work was funded by several scientific research programs including Evaluation and Optimal Target Selection of Deep Geothermal Resources in the Igneous Region of South China(No.:2019YFC0604903)Analysis and Geothermal Reservoir Stimulation Methods of Deep High-temperature Geothermal Systems in East China(No.:2021YFA0716004)+1 种基金the National Key Research and Development Program of China,Deep Geological Processes and Resource Effects of Basins(No.:U20B6001)the Joint Fund Program of the National Natural Science Foundation of China and Sinopec,and Siting and Target Evaluation of Deep Geothermal Resources in Key Areas of Southeastern China(No.:P20041-1)of the Sinopec Science and Technology Research Program.
文摘Cap rocks with high thermal insulation are important for deep geothermal systems at a depth of 3000‒6000 m.Based on the deep geothermal geological conditions in the Fujian-Guangdong-Hainan area of South China,this study established an ideal geological model of reservoir-cap rock assemblages and simulated the geothermal field distribution of cap rocks of different thicknesses and thermal conductivity.The simulation results show that the vertical geothermal temperature distribution in an uplifted area of a depression was present as inverted mirror reflections relative to the elevated area of the basement.Specifically,the isotherms above the elevated area are convex in shape,while those below the elevated area are concave.There is a temperature equilibrium line between the convex and concave isotherms.The heat flow moves from the depressed area to the uplifted area below the temperature equilibrium line and migrates in an opposite direction above the line.On this base,this study conducted the inversion of geothermal temperature fields in typical areas with thin,moderately thick,and thick cap rocks.The results indicate that,at the depth of 3000e6000 m,areas with thin cap rocks(igneous rock zone in the coastal area of Fujian)mainly host moderate-to low-temperature hydrothermal resources;areas with moderately thick cap rocks(Yuezhong Depression)have the geothermal temperature ranging between 100℃and 200℃and may develop moderate-to high-temperature hydrothermal resources and hot dry rocks(HDRs),with the former superimposing on the latter;and areas with thick cap rocks(onshore Beibuwan Basin)have a geothermal temperature of 120‒220℃,and contains mainly moderate-to high-temperature hydrothermal resources and HDRs.Therefore,it is recommended that the evaluation,exploitation,and utilization of deep geothermal resources be carried out according to the burial depth of the temperature equilibrium line and the specific demand for geothermal resources.
