Changes in the water cycle on the Tibetan Plateau(TP)have a significant impact on local agricultural production and livelihoods and its downstream regions.Against the background of widely reported warming and wetting,...Changes in the water cycle on the Tibetan Plateau(TP)have a significant impact on local agricultural production and livelihoods and its downstream regions.Against the background of widely reported warming and wetting,the hydrological cycle has accelerated and the likelihood of extreme weather events and natural disasters occurring(i.e.,snowstorms,floods,landslides,mudslides,and ice avalanches)has also intensified,especially in the highelevation mountainous regions.Thus,an accurate estimation of the intensity and variation of each component of the water cycle is an urgent scientific question for the assessment of plateau environmental changes.Following the transformation and movement of water between the atmosphere,biosphere and hydrosphere,the authors highlight the urgent need to strengthen the three-dimensional comprehensive observation system(including the eddy covariance system;planetary boundary layer tower;profile measurements of temperature,humidity,and wind by microwave radiometers,wind profiler,and radiosonde system;and cloud and precipitation radars)in the TP region and propose a practical implementation plan.The construction of such a three-dimensional observation system is expected to promote the study of environmental changes and natural hazards prevention.展开更多
Significant exploration progress has been made in ultra-deep clastic rocks in the Kuqa Depression,Tarim Basin,over recent years.A new round of comprehensive geological research has formed four new understandings:(1)Es...Significant exploration progress has been made in ultra-deep clastic rocks in the Kuqa Depression,Tarim Basin,over recent years.A new round of comprehensive geological research has formed four new understandings:(1)Establish structural model consisting of multi-detachment composite,multi-stage structural superposition and multi-layer deformation.Multi-stage structural traps are overlapped vertically,and a series of structural traps are discovered in underlying ultra-deep layers.(2)Five sets of high-quality large-scale source rocks of three types of organic phases are developed in the Triassic and Jurassic systems,and forming a good combination of source-reservoir-cap rocks in ultra-deep layers with three sets of large-scale regional reservoir and cap rocks.(3)The formation of large oil and gas fields is controlled by four factors which are source,reservoir,cap rocks and fault.Based on the spatial configuration relationship of these four factors,a new three-dimensional reservoir formation model for ultra-deep clastic rocks in the Kuqa Depression has been established.(4)The next key exploration fields for ultra-deep clastic rocks in the Kuqa Depression include conventional and unconventional oil and gas.The conventional oil and gas fields include the deep multi-layer oil-gas accumulation zone in Kelasu,tight sandstone gas of Jurassic Ahe Formation in the northern structural zone,multi-target layer lithological oil and gas reservoirs in Zhongqiu–Dina structural zone,lithologic-stratigraphic and buried hill composite reservoirs in south slope and other favorable areas.Unconventional oil and gas fields include deep coal rock gas of Jurassic Kezilenuer and Yangxia formations,Triassic Tariqike Formation and Middle-Lower Jurassic and Upper Triassic continental shale gas.The achievements have important reference significance for enriching the theory of ultra-deep clastic rock oil and gas exploration and guiding the future oil and gas exploration deployment.展开更多
To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets ...To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets of concealed ore bodies,three-dimensional Mineral Prospectivity Modeling(MPM)of the deposit has been conducted using the weights-of-evidence(WofE)method.Conditional independence between evidence layers was tested,and the outline results using the prediction-volume(P-V)and Student's t-statistic methods for delineating favorable mineralization areas from continuous posterior probability map were critically compared.Four exploration targets delineated ultimately by the Student's t-statistic method for the discovery of minable ore bodies in each of the target areas were discussed in detail.The main conclusions include:(1)three-dimensional modeling of a deposit using multi-source reconnaissance data is useful for MPM in interpreting their relationships with known ore bodies;(2)WofE modeling can be used as a straightforward tool for integrating deposit model and reconnaissance data in MPM;(3)the Student's t-statistic method is more applicable in binarizing the continuous prospectivity map for exploration targeting than the PV approach;and(4)two target areas within high potential to find undiscovered ore bodies were diagnosed to guide future near-mine exploration activities of the Jinshan deposit.展开更多
Three-dimensional(3 D)gravitational and magnetic exploration is performed using aerial measurement tools,however,this has difficulties with measuring-height design and the construction of a joint-interpretation scheme...Three-dimensional(3 D)gravitational and magnetic exploration is performed using aerial measurement tools,however,this has difficulties with measuring-height design and the construction of a joint-interpretation scheme.At present,the height in such experiments is set according to the measurement scale,and the distribution characteristics of anomalies are not fully considered.Here,we present the idea of using the attenuation characteristics of a singular-value spectrum to evaluate the contributions of various measurement heights and multi-height combinations for inversion to correctly and reasonably design appropriate measuring heights and the number of various measurement heights to be set.The jointgradient Euler-deconvolution method can accurately obtain the distribution of geological bodies from 3 D gravitational and magnetic data at an improved resolution,and experimental tests confirm these findings.Therefore,an actual 3 D aeromagnetic-data-acquisition and inversion test were carried out in the vicinity of the Zhurihe Iron Mine in Inner Mongolia.The fl ight-height diff erence was set to 60 m,and the specifi c distribution of lodes was obtained by the joint-gradient Euler-deconvolution method.This provides a reliable basis for future detailed exploration and proves that the methods presented in this paper have good practicalapplication eff ects and prospects.展开更多
Intermediate acid-complex rock masses with low-density characteristics are the most important prospecting sign in the Beiya area, of western Yunnan province, and provide a physical basis for good gravity exploration. ...Intermediate acid-complex rock masses with low-density characteristics are the most important prospecting sign in the Beiya area, of western Yunnan province, and provide a physical basis for good gravity exploration. It is usually difficult to obtaining solutions in connection with actual geological situations due to the ambiguity of the conventional gravity-processing results and lack of deep constraints. Thus, the three-dimensional (3D) inversion technology is considered as the main channel for reducing the number of solutions and improving the vertical resolution at the current stage. The current study starts from a model test and performs nonlinear 3D density-difference inversion called “model likelihood exploration”, which performs 3D inversion imaging and inversion of the known model while considering the topographic effects. The inversion results are highly consistent with those of the known models. Simultaneously, we consider the Beiya gold mine in Yunnan as an example. The nonlinear 3D densitydifference inversion technology, which is restricted by geological information, is explored to obtain the 3D density body structure below 5 km in the mine area, and the 3D structure of the deep and concealed rock masses are obtained using the density constraints of the intermediate-acid-complex rock masses. The results are well consistent with the surface geological masses and drilling-controlled deep geological masses. The model test and examples both show that the 3D density-difference nonlinear inversion technology can reduce inversion ambiguity, improve resolution, optimize the inversion results, and realize “transparency” in deeply concealed rock masses in ore-concentrated areas,which is useful in guiding the deep ore prospecting.展开更多
The Sichuan Basin represents the earliest area where natural gas is explored,developed and comprehensively utilized in China.After over 50 years of oil and gas exploration,oil and gas reservoirs have been discovered i...The Sichuan Basin represents the earliest area where natural gas is explored,developed and comprehensively utilized in China.After over 50 years of oil and gas exploration,oil and gas reservoirs have been discovered in 24 gas-dominant layers in this basin.For the purpose of predicting natural gas exploration direction and target of each layer in the Sichuan Basin,the sedimentary characteristics of marine and continental strata in this basin were summarized and the forms of multi-cycled tectonic movement and their controlling effect on sedimentation,diagenesis and hydrocarbon accumulation were analyzed.Based on the analysis,the following characteristics were identified.First,the Sichuan Basin has experienced the transformation from marine sedimentation to continental sedimentation since the Sinian with the former being dominant.Second,multiple sourceereservoir assemblages are formed based on multi-rhythmed deposition,and multi-layered reservoir hydrocarbon accumulation characteristics are vertically presented.And third,multi-cycled tectonic movement appears in many forms and has a significant controlling effect on sedimentation,diagenesis and hydrocarbon accumulation.Then,oil and gas reservoir characteristics and enrichment laws were investigated.It is indicated that the Sichuan Basin is characterized by coexistence of conventional and unconventional oil and gas reservoirs,multi-layered reservoir hydrocarbon supply,multiple reservoir types,multiple trap types,multi-staged hydrocarbon accumulation and multiple hydrocarbon accumulation models.Besides,its natural gas enrichment is affected by hydrocarbon source intensity,large paleo-uplift,favorable sedimentary facies belt,sedimentaryestructural discontinuity plane and structural fracture development.Finally,the natural gas exploration and research targets of each layer in the Sichuan Basin were predicted according to the basic petroleum geologic conditions,enrichment laws and exploration status.展开更多
At present,the increase in proved reserves and production of coalbed methane(CBM)in China depends mainly on several CBM bases in the southern Qinshui Basin and in the eastern margin of the Ordos Basin.Therefore,it is ...At present,the increase in proved reserves and production of coalbed methane(CBM)in China depends mainly on several CBM bases in the southern Qinshui Basin and in the eastern margin of the Ordos Basin.Therefore,it is urgent to find new batches of exploration and development strategic replacement areas.For this purpose,we investigated the resources,reservoir properties,preservation conditions,and development conditions of CBM in China,and put forward eight general factors and four critical factors that can be used in establishing selection criteria of strategic replacement areas for affecting the CBM exploration and development in China.The eight general factors are resource abundance,coalbed thickness,gas content,original permeability,burial depth,hydrogeological conditions,coalbed depositional environment,and landforms,and the four critical factors include genetic type,stability type,later reservoir reformation,and damage degree of coal structure.Comparison shows that the low-rank coal area in the northwestern area,the northeastern medium-low rank coal area,and the southwestern medium-high rank and structurally-complex coal area are the major replacement areas for CBM following the northern area of China.Key factors affecting CBM enrichment in each of the three key areas,respectively,are:a)genetic type and stability of coal seams,b)genetic type and reconstruction of the reservoir by volcanic intrusion,and c)stability of coal seams and damage degree of coal structure.Based on these factors,a system for selection and evaluation of strategic replacement areas for CBM development was established.Fifteen blocks in the above three areas were evaluated by using multi-layered fuzzy mathematics,selecting eight favorable areas and seven relatively favorable areas that contain 1.8 trillion m^(3) of predicted CBM geological resources.The eight favorable areas include the Wucaiwan-Dajing coal exploration area in the Zhundong coalfield(eastern Junggar Basin),the Hami-Dananhu mining area in the Turpan-Hami Basin,the Longdong coalfield(eastern Gansu Province),the Yilan and Hegang coalfields in eastern Heilongjiang Province,the Hunchun coalfield in Jilin Province,the southern Sichuan coalfield,and the Shuicheng coalfield in Guizhou Province.These favorable areas were recommended to be the CBM exploration and pilot development target areas in the near future.展开更多
The Transient Electromagnetic(TEM)method is a critical geophysical technique for subsurface exploration of metal ore bodies,primarily utilizing either loop or grounded transmitters.The Long Offset Transient Electromag...The Transient Electromagnetic(TEM)method is a critical geophysical technique for subsurface exploration of metal ore bodies,primarily utilizing either loop or grounded transmitters.The Long Offset Transient Electromagnetic(LOTEM)method employs a grounded-source transmitter,relying on a far-source observation mode and plane wave approximation for detection.However,LOTEM's far-source configuration weakens signal strength,and the plane wave approximation reduces precision,limiting effective detection depth to approximately 1000 m with a comprehensive error of about 15%.Recently,we have developed the grounded-source Short Offset Transient Electromagnetic(SOTEM)method,achieving greater detection depth and accuracy within the 500–2000 m depth range,a crucial interval for mineral resource exploration.This study explores the theoretical framework,instrumentation,data processing,and field applications of SOTEM.Based on a point charge element model,SOTEM accurately computes surface wave effects in EM field calculations,optimized for near-source observation.High-power,high-resolution,wide-bandwidth exploration equipment and an advanced three-dimensional hybrid inversion technique were also developed to enhance the method's effectiveness.Application of SOTEM to the deep exploration of the Zhou'an Ni-Cu-PGE deposit in Henan Province yielded high-resolution imaging of conductivity structures to about 2.5 km depth.These results,consistent with existing drill data,delineated mineralized ore bodies from surrounding formations,identified zones of mineralization potential,and suggested extensive resource prospects in the region.展开更多
The Keshen gas field is located in the central part of Kuqa foreland thrust belt in Tarim Basin,and is another large gas field discovered in Kuqa depression after Kela 2 gas field.Since the breakthrough in 2008,a numb...The Keshen gas field is located in the central part of Kuqa foreland thrust belt in Tarim Basin,and is another large gas field discovered in Kuqa depression after Kela 2 gas field.Since the breakthrough in 2008,a number of large and medium scale gas reservoirs including Keshen 2,Keshen 5 and Keshen 8 have been discovered,that are characterized by ultra depth,ultra-high pressure,ultra-low porosity,ultra-low permeability,high temperature and high pressure.With natural gas geological reserves of nearly trillion cubic meters and production capacity of nearly 5.5 billion cubic meters,the Keshen gas field is the main natural gas producing area in Tarim Oilfield.The Keshen gas field is located in a series of thrusting imbrication structures in the Kelasu structural belt of Kuqa foreland thrust belt.The salt roof structure,plastic rheology of salt beds and pre-salt faulted anticlinal structure constitute the large wedge-shaped thrust body.The thick delta sandstone of the Cretaceous Bashijike Formation is widely distributed,and it forms the superior reservoir-caprock combination with overlying Paleogene thick gypsum-salt bed.The deep Jurassic-Triassic oil and gas migrate vertically along fault system formed in Late Himalaya,break through the thick Cretaceous mudstone and move laterally along the fracture system of the pre-salt reservoirs,to form anticline and fault anticline high pressure reservoir groups.Through near ten years of studies,the three-dimensional seismic acquisition and processing technology for complex mountainous areas,extrusion salt-related structural modeling technology and fractured low-porosity sandstone reservoir evaluation technology have been established,which lay a foundation for realization of oil and gas exploration objectives.Logging acquisition and evaluation technology for high temperature,high pressure,ultra-deep and low-porosity sandstone gas reservoirs,and efficient development technology for fractured tight sandstone gas reservoirs have been developed,which provide a technical support for efficient exploration&development and rapid production of the Keshen gas field.展开更多
Based on an expressway project in Hangzhou, this paper analyzes and studies the cross construction of one section of three-dimensional multi-storey bridge across the river, optimizes the construction organization and ...Based on an expressway project in Hangzhou, this paper analyzes and studies the cross construction of one section of three-dimensional multi-storey bridge across the river, optimizes the construction organization and arrangement, and cross-constructs the ground road framing bridge and the upper elevated bridge, so as to reduce the mutual interference in the cross construction process through scientific construction techniques, guarantee the bridge engineering quality and reduce the impact on urban traffic. Through the discussion of cross-engineering construction technology in this paper, it is expected to provide experience for similar bridge construction in China.展开更多
基金This research was jointly funded by the Second Tibetan Plateau Scientific Expedition and Research Program(Grant Nos.2019QZKK0103 and 2019QZKK0105)the National Natural Science Foundation of China(Grant Nos.91837208 and 42075085).
文摘Changes in the water cycle on the Tibetan Plateau(TP)have a significant impact on local agricultural production and livelihoods and its downstream regions.Against the background of widely reported warming and wetting,the hydrological cycle has accelerated and the likelihood of extreme weather events and natural disasters occurring(i.e.,snowstorms,floods,landslides,mudslides,and ice avalanches)has also intensified,especially in the highelevation mountainous regions.Thus,an accurate estimation of the intensity and variation of each component of the water cycle is an urgent scientific question for the assessment of plateau environmental changes.Following the transformation and movement of water between the atmosphere,biosphere and hydrosphere,the authors highlight the urgent need to strengthen the three-dimensional comprehensive observation system(including the eddy covariance system;planetary boundary layer tower;profile measurements of temperature,humidity,and wind by microwave radiometers,wind profiler,and radiosonde system;and cloud and precipitation radars)in the TP region and propose a practical implementation plan.The construction of such a three-dimensional observation system is expected to promote the study of environmental changes and natural hazards prevention.
基金Supported by the National Natural Science Foundation of China(U22B6002)PetroChina Science and Technology Project(2023ZZ14).
文摘Significant exploration progress has been made in ultra-deep clastic rocks in the Kuqa Depression,Tarim Basin,over recent years.A new round of comprehensive geological research has formed four new understandings:(1)Establish structural model consisting of multi-detachment composite,multi-stage structural superposition and multi-layer deformation.Multi-stage structural traps are overlapped vertically,and a series of structural traps are discovered in underlying ultra-deep layers.(2)Five sets of high-quality large-scale source rocks of three types of organic phases are developed in the Triassic and Jurassic systems,and forming a good combination of source-reservoir-cap rocks in ultra-deep layers with three sets of large-scale regional reservoir and cap rocks.(3)The formation of large oil and gas fields is controlled by four factors which are source,reservoir,cap rocks and fault.Based on the spatial configuration relationship of these four factors,a new three-dimensional reservoir formation model for ultra-deep clastic rocks in the Kuqa Depression has been established.(4)The next key exploration fields for ultra-deep clastic rocks in the Kuqa Depression include conventional and unconventional oil and gas.The conventional oil and gas fields include the deep multi-layer oil-gas accumulation zone in Kelasu,tight sandstone gas of Jurassic Ahe Formation in the northern structural zone,multi-target layer lithological oil and gas reservoirs in Zhongqiu–Dina structural zone,lithologic-stratigraphic and buried hill composite reservoirs in south slope and other favorable areas.Unconventional oil and gas fields include deep coal rock gas of Jurassic Kezilenuer and Yangxia formations,Triassic Tariqike Formation and Middle-Lower Jurassic and Upper Triassic continental shale gas.The achievements have important reference significance for enriching the theory of ultra-deep clastic rock oil and gas exploration and guiding the future oil and gas exploration deployment.
基金financially supported by the Ministry of Science and Technology of China(Nos.2022YFF0801201,2021YFC2900300)the National Natural Science Foundation of China(Nos.41872245,U1911202)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010666)。
文摘To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets of concealed ore bodies,three-dimensional Mineral Prospectivity Modeling(MPM)of the deposit has been conducted using the weights-of-evidence(WofE)method.Conditional independence between evidence layers was tested,and the outline results using the prediction-volume(P-V)and Student's t-statistic methods for delineating favorable mineralization areas from continuous posterior probability map were critically compared.Four exploration targets delineated ultimately by the Student's t-statistic method for the discovery of minable ore bodies in each of the target areas were discussed in detail.The main conclusions include:(1)three-dimensional modeling of a deposit using multi-source reconnaissance data is useful for MPM in interpreting their relationships with known ore bodies;(2)WofE modeling can be used as a straightforward tool for integrating deposit model and reconnaissance data in MPM;(3)the Student's t-statistic method is more applicable in binarizing the continuous prospectivity map for exploration targeting than the PV approach;and(4)two target areas within high potential to find undiscovered ore bodies were diagnosed to guide future near-mine exploration activities of the Jinshan deposit.
基金supported by the National Key Research and Development Program of China (Nos. 2017YFC0602203,2017YFC0601606,2017YFC0601305 and 2017YFC0602000)National Science and Technology Major Project task (No.2016ZX05027-002-003)+1 种基金National Natural Science Foundation of China (No. 41604098)State Key Program of National Natural Science of China (No. 41430322)。
文摘Three-dimensional(3 D)gravitational and magnetic exploration is performed using aerial measurement tools,however,this has difficulties with measuring-height design and the construction of a joint-interpretation scheme.At present,the height in such experiments is set according to the measurement scale,and the distribution characteristics of anomalies are not fully considered.Here,we present the idea of using the attenuation characteristics of a singular-value spectrum to evaluate the contributions of various measurement heights and multi-height combinations for inversion to correctly and reasonably design appropriate measuring heights and the number of various measurement heights to be set.The jointgradient Euler-deconvolution method can accurately obtain the distribution of geological bodies from 3 D gravitational and magnetic data at an improved resolution,and experimental tests confirm these findings.Therefore,an actual 3 D aeromagnetic-data-acquisition and inversion test were carried out in the vicinity of the Zhurihe Iron Mine in Inner Mongolia.The fl ight-height diff erence was set to 60 m,and the specifi c distribution of lodes was obtained by the joint-gradient Euler-deconvolution method.This provides a reliable basis for future detailed exploration and proves that the methods presented in this paper have good practicalapplication eff ects and prospects.
基金The authors would like to thank the China Geological Survey (DD20190033)National Natural Science Foundation (41804144) for the financial support,Yunnan Gold and Mineral Group Co.,Ltd. for providing the original geological information,and the reviewers for providing valuable comments.
文摘Intermediate acid-complex rock masses with low-density characteristics are the most important prospecting sign in the Beiya area, of western Yunnan province, and provide a physical basis for good gravity exploration. It is usually difficult to obtaining solutions in connection with actual geological situations due to the ambiguity of the conventional gravity-processing results and lack of deep constraints. Thus, the three-dimensional (3D) inversion technology is considered as the main channel for reducing the number of solutions and improving the vertical resolution at the current stage. The current study starts from a model test and performs nonlinear 3D density-difference inversion called “model likelihood exploration”, which performs 3D inversion imaging and inversion of the known model while considering the topographic effects. The inversion results are highly consistent with those of the known models. Simultaneously, we consider the Beiya gold mine in Yunnan as an example. The nonlinear 3D densitydifference inversion technology, which is restricted by geological information, is explored to obtain the 3D density body structure below 5 km in the mine area, and the 3D structure of the deep and concealed rock masses are obtained using the density constraints of the intermediate-acid-complex rock masses. The results are well consistent with the surface geological masses and drilling-controlled deep geological masses. The model test and examples both show that the 3D density-difference nonlinear inversion technology can reduce inversion ambiguity, improve resolution, optimize the inversion results, and realize “transparency” in deeply concealed rock masses in ore-concentrated areas,which is useful in guiding the deep ore prospecting.
文摘The Sichuan Basin represents the earliest area where natural gas is explored,developed and comprehensively utilized in China.After over 50 years of oil and gas exploration,oil and gas reservoirs have been discovered in 24 gas-dominant layers in this basin.For the purpose of predicting natural gas exploration direction and target of each layer in the Sichuan Basin,the sedimentary characteristics of marine and continental strata in this basin were summarized and the forms of multi-cycled tectonic movement and their controlling effect on sedimentation,diagenesis and hydrocarbon accumulation were analyzed.Based on the analysis,the following characteristics were identified.First,the Sichuan Basin has experienced the transformation from marine sedimentation to continental sedimentation since the Sinian with the former being dominant.Second,multiple sourceereservoir assemblages are formed based on multi-rhythmed deposition,and multi-layered reservoir hydrocarbon accumulation characteristics are vertically presented.And third,multi-cycled tectonic movement appears in many forms and has a significant controlling effect on sedimentation,diagenesis and hydrocarbon accumulation.Then,oil and gas reservoir characteristics and enrichment laws were investigated.It is indicated that the Sichuan Basin is characterized by coexistence of conventional and unconventional oil and gas reservoirs,multi-layered reservoir hydrocarbon supply,multiple reservoir types,multiple trap types,multi-staged hydrocarbon accumulation and multiple hydrocarbon accumulation models.Besides,its natural gas enrichment is affected by hydrocarbon source intensity,large paleo-uplift,favorable sedimentary facies belt,sedimentaryestructural discontinuity plane and structural fracture development.Finally,the natural gas exploration and research targets of each layer in the Sichuan Basin were predicted according to the basic petroleum geologic conditions,enrichment laws and exploration status.
基金work has been supported by the China Geological Survey Scientific Research Project 1212011220794the National Science and Technology Major Project 2011ZX 05033-002.
文摘At present,the increase in proved reserves and production of coalbed methane(CBM)in China depends mainly on several CBM bases in the southern Qinshui Basin and in the eastern margin of the Ordos Basin.Therefore,it is urgent to find new batches of exploration and development strategic replacement areas.For this purpose,we investigated the resources,reservoir properties,preservation conditions,and development conditions of CBM in China,and put forward eight general factors and four critical factors that can be used in establishing selection criteria of strategic replacement areas for affecting the CBM exploration and development in China.The eight general factors are resource abundance,coalbed thickness,gas content,original permeability,burial depth,hydrogeological conditions,coalbed depositional environment,and landforms,and the four critical factors include genetic type,stability type,later reservoir reformation,and damage degree of coal structure.Comparison shows that the low-rank coal area in the northwestern area,the northeastern medium-low rank coal area,and the southwestern medium-high rank and structurally-complex coal area are the major replacement areas for CBM following the northern area of China.Key factors affecting CBM enrichment in each of the three key areas,respectively,are:a)genetic type and stability of coal seams,b)genetic type and reconstruction of the reservoir by volcanic intrusion,and c)stability of coal seams and damage degree of coal structure.Based on these factors,a system for selection and evaluation of strategic replacement areas for CBM development was established.Fifteen blocks in the above three areas were evaluated by using multi-layered fuzzy mathematics,selecting eight favorable areas and seven relatively favorable areas that contain 1.8 trillion m^(3) of predicted CBM geological resources.The eight favorable areas include the Wucaiwan-Dajing coal exploration area in the Zhundong coalfield(eastern Junggar Basin),the Hami-Dananhu mining area in the Turpan-Hami Basin,the Longdong coalfield(eastern Gansu Province),the Yilan and Hegang coalfields in eastern Heilongjiang Province,the Hunchun coalfield in Jilin Province,the southern Sichuan coalfield,and the Shuicheng coalfield in Guizhou Province.These favorable areas were recommended to be the CBM exploration and pilot development target areas in the near future.
基金supported by the National Natural Science Foundation of China(Grant Nos.42030106,42274192)the National Key Research and Development Program of China(Grant No.2022YFC2903505)。
文摘The Transient Electromagnetic(TEM)method is a critical geophysical technique for subsurface exploration of metal ore bodies,primarily utilizing either loop or grounded transmitters.The Long Offset Transient Electromagnetic(LOTEM)method employs a grounded-source transmitter,relying on a far-source observation mode and plane wave approximation for detection.However,LOTEM's far-source configuration weakens signal strength,and the plane wave approximation reduces precision,limiting effective detection depth to approximately 1000 m with a comprehensive error of about 15%.Recently,we have developed the grounded-source Short Offset Transient Electromagnetic(SOTEM)method,achieving greater detection depth and accuracy within the 500–2000 m depth range,a crucial interval for mineral resource exploration.This study explores the theoretical framework,instrumentation,data processing,and field applications of SOTEM.Based on a point charge element model,SOTEM accurately computes surface wave effects in EM field calculations,optimized for near-source observation.High-power,high-resolution,wide-bandwidth exploration equipment and an advanced three-dimensional hybrid inversion technique were also developed to enhance the method's effectiveness.Application of SOTEM to the deep exploration of the Zhou'an Ni-Cu-PGE deposit in Henan Province yielded high-resolution imaging of conductivity structures to about 2.5 km depth.These results,consistent with existing drill data,delineated mineralized ore bodies from surrounding formations,identified zones of mineralization potential,and suggested extensive resource prospects in the region.
基金The work was supported by the National Science and Technology Major Project of China(No.2016ZX05003-004).
文摘The Keshen gas field is located in the central part of Kuqa foreland thrust belt in Tarim Basin,and is another large gas field discovered in Kuqa depression after Kela 2 gas field.Since the breakthrough in 2008,a number of large and medium scale gas reservoirs including Keshen 2,Keshen 5 and Keshen 8 have been discovered,that are characterized by ultra depth,ultra-high pressure,ultra-low porosity,ultra-low permeability,high temperature and high pressure.With natural gas geological reserves of nearly trillion cubic meters and production capacity of nearly 5.5 billion cubic meters,the Keshen gas field is the main natural gas producing area in Tarim Oilfield.The Keshen gas field is located in a series of thrusting imbrication structures in the Kelasu structural belt of Kuqa foreland thrust belt.The salt roof structure,plastic rheology of salt beds and pre-salt faulted anticlinal structure constitute the large wedge-shaped thrust body.The thick delta sandstone of the Cretaceous Bashijike Formation is widely distributed,and it forms the superior reservoir-caprock combination with overlying Paleogene thick gypsum-salt bed.The deep Jurassic-Triassic oil and gas migrate vertically along fault system formed in Late Himalaya,break through the thick Cretaceous mudstone and move laterally along the fracture system of the pre-salt reservoirs,to form anticline and fault anticline high pressure reservoir groups.Through near ten years of studies,the three-dimensional seismic acquisition and processing technology for complex mountainous areas,extrusion salt-related structural modeling technology and fractured low-porosity sandstone reservoir evaluation technology have been established,which lay a foundation for realization of oil and gas exploration objectives.Logging acquisition and evaluation technology for high temperature,high pressure,ultra-deep and low-porosity sandstone gas reservoirs,and efficient development technology for fractured tight sandstone gas reservoirs have been developed,which provide a technical support for efficient exploration&development and rapid production of the Keshen gas field.
文摘Based on an expressway project in Hangzhou, this paper analyzes and studies the cross construction of one section of three-dimensional multi-storey bridge across the river, optimizes the construction organization and arrangement, and cross-constructs the ground road framing bridge and the upper elevated bridge, so as to reduce the mutual interference in the cross construction process through scientific construction techniques, guarantee the bridge engineering quality and reduce the impact on urban traffic. Through the discussion of cross-engineering construction technology in this paper, it is expected to provide experience for similar bridge construction in China.
