Current machine learning models for predicting geological conditions during earth pressure balance(EPB)shield tunneling predominantly rely on accurate geological conditions as model label inputs.This study introduces ...Current machine learning models for predicting geological conditions during earth pressure balance(EPB)shield tunneling predominantly rely on accurate geological conditions as model label inputs.This study introduces an innovative approach for the real-time prediction of geological conditions in EPB shield tunneling by utilizing an unsupervised incremental learning model that integrates deep temporal clustering(DTC)with elastic weight consolidation(EWC).The model was trained and tested using data from an EPB shield tunneling project in Nanjing,China.Results demonstrate that the DTC model outperforms nine comparison models by clustering the entire dataset into four distinct groups representing various geological conditions without requiring labeled data.Additionally,integrating EWC into the DTC model significantly enhances its continuous learning capabilities,enabling automatic parameter updates with incoming data and facilitating the real-time recognition of geological conditions.Feature importance was evaluated using the feature elimination method and the Shapley additive explanations(SHAP)method,underscoring the critical roles of earth chamber pressure and cutterhead rotation speed in predicting geological conditions.The proposed EWC-DTC model demonstrates practical utility for EPB shield tunneling in complex environments.展开更多
China is home to shales of three facies:Marine shale,continental shale,and marine-continental transitional shale.Different types of shale gas are associated with significantly different formation conditions and major ...China is home to shales of three facies:Marine shale,continental shale,and marine-continental transitional shale.Different types of shale gas are associated with significantly different formation conditions and major controlling factors.This study compared the geological characteristics of various shales and analyzed the influences of different parameters on the formation and accumulation of shale gas.In general,shales in China’s several regions exhibit high total organic carbon(TOC)contents,which lays a sound material basis for shale gas generation.Marine strata generally show high degrees of thermal evolution.In contrast,continental shales manifest low degrees of thermal evolution,necessitating focusing on areas with relatively high degrees of thermal evolution in the process of shale gas surveys for these shales.The shales of the Wufeng and Silurian formations constitute the most favorable shale gas reservoirs since they exhibit the highest porosity among the three types of shales.These shales are followed by those in the Niutitang and Longtan formations.In contrast,the shales of the Doushantuo,Yanchang,and Qingshankou formations manifest low porosities.Furthermore,the shales of the Wufeng and Longmaxi formations exhibit high brittle mineral contents.Despite a low siliceous mineral content,the shales of the Doushantuo Formation feature a high carbonate mineral content,which can increase the shales’brittleness to some extent.For marine-continental transitional shales,where thin interbeds of tight sandstone with unequal thicknesses are generally found,it is recommended that fracturing combined with drainage of multiple sets of lithologic strata should be employed to enhance their shale gas production.展开更多
Almost all the coal is produced from open cut mines in Indonesia. As a consequence of open cut mine application, a great deal of coal is left out in the highwalls of the mined-out pits. Highwall mining systems can be ...Almost all the coal is produced from open cut mines in Indonesia. As a consequence of open cut mine application, a great deal of coal is left out in the highwalls of the mined-out pits. Highwall mining systems can be used to recover this coal. The use of highwall mining systems has increasingly come into play in the US and Australia. However, it is not common in Indonesia. Moreover, Indonesia coal measure is categorized as weak geological condition. Some problems are likely to arise during the application of the highwall mining system for example instability of openings and highwalls due to the roof and pillar failures. Therefore, study of highwall mining system application in Indonesia is needed in order to increase the recovery rate of coal mining in Indonesia. This paper described the characteristics of the highwa!l mining system and discussed the appropriate highwall mining system application in weak geological condition, Indonesia. From the results of a series of laboratory tests and numerical analyses, it can be concluded that the stability of pillars and mine openings in auger mining systems is much higher than that in CHM and an auger mining system is suitable for such as very weak/poor strata conditions. Moreover, the application of backfilling system is very effective for improvement of the stability of pillar and openings.展开更多
The South Yellow Sea Basin(SYSB) has multiple sets of proven source rocks and good hydrocarbon prospects,but no industrial oil and gas has been explored at present.To solve this puzzle for petroleum geologists,we syst...The South Yellow Sea Basin(SYSB) has multiple sets of proven source rocks and good hydrocarbon prospects,but no industrial oil and gas has been explored at present.To solve this puzzle for petroleum geologists,we systematically investigated the marine hydrocarbon geological conditions based on cores and testing data from borehole CSDP-2,the first exploration well with continuous coring in SYSB.The qualities of source rocks are evaluated in detail according to organic matter abundance,type,and maturity.The reservoir characterization mainly includes porosity,permeability,and reservoir space.Displacement pressure test and stratum thickness are the main foundations for defining the caprocks.Then,the oil-source rock correlation in the Permian and stratum model are analyzed to determine the favorable source-reservoir-caprock assemblages.The results show that three sets of effective source rocks(the Lower Triassic,Upper Permian,and Lower Permian),two sets of tight sandstone re servoirs(the Upper Permian and Lower Silurian-Upper Devonian),and two sets of caprocks(the Lower Triassic and Carboniferous) combine to constitute the hydrocarbon reservoir-forming as se mblages of "lower-ge neration and upper-accumlation" and "self-generation and self-accumlation",thus laying a solid foundation for promising petroleum prospects.The three sets of marine source rocks are characterized by successive generation and expulsion stages,which guarantees multistage hydrocarbon accumulation.Another three sets of continental source rocks distributed across the Middle Jurassic,Upper Cretaceous,and Paleogene depression areas,especially in the Northern Depression,may supplement some hydrocarbons for the Central Uplift through faults and the Indosinian unconformity.The favorable Permian exploration strata have been identified in the Central Uplift of SYSB.First,the Lower Permian and Upper Permian source rocks with high organic matter abundance and high thermal maturity supply sufficient hydrocarbons.Secondly,the interbedding relationship between the source rocks and sandstones in the Upper Permian strata ensures that hydrocarbons have been migrated into the nearby Upper Permian sandstones,reflecting near-source hydrocarbon accumulation.Finally,the good sealing property of the Lower Triassic Qinglong Formation caprocks plays an indispensable role in hydrocarbon preservation of the Permian reservoirs.This conclusion is supported by direct oil shows,gas logging anomalous layers,and hydrocarbon-bearing fluid inclusions.展开更多
The presence of shale gas has been confirmed in almost every marine shale distribution area in North America.Formation conditions of shale gas in China are the most favorable for marine,organic-rich shale as well.But ...The presence of shale gas has been confirmed in almost every marine shale distribution area in North America.Formation conditions of shale gas in China are the most favorable for marine,organic-rich shale as well.But there has been little research focusing on shale gas in Qiangtang Basin,Qinghai-Tibet Plateau,where a lot of Mesozoic marine shale formations developed.Based on the survey results of petroleum geology and comprehensive test analysis data for Qinghai-Tibet Plateau,for the first time,this paper discusses characteristics of sedimentary development,thickness distribution,geochemistry,reservoir and burial depth of organic-rich shale,and geological conditions for shale gas formation in Qiangtang Basin.There are four sets of marine shale strata in Qiangtang Basin including Upper Triassic Xiaochaka Formation （T3x）,Middle Jurassic Buqu Formation （J2b）,Xiali Formation （J2x） and Upper Jurassic Suowa Formation （J3s）,the sedimentary types of which are mainly bathyal-basin facies,open platform-platform margin slope facies,lagoon and tidal-fiat facies,as well as delta facies.By comparing it with the indicators of gas shale in the main U.S.basins,it was found that the four marine shale formations in Qiangtang Basin constitute a multi-layer distribution of organic-rich shale,featuring a high degree of thickness and low abundance of organic matter,high thermal evolution maturity,many kinds of brittle minerals,an equivalent content of quartz and clay minerals,a high content of feldspar and low porosity,which provide basic conditions for an accumulation of shale gas resources.Xiaochaka Formation shale is widely distributed,with big thickness and the best gas generating indicators.It is the main gas source layer.Xiali Formation shale is of intermediate thickness and coverage area,with relatively good gas generating indicators and moderate gas formation potential.Buqu Formation shale and Suowa Formation shale are of relatively large thickness,and covering a small area,with poor gas generating indicators,and limited gas formation potential.The shale gas geological resources and technically recoverable resources were estimated by using geologic analogy method,and the prospective areas and potentially favorable areas for Mesozoic marine shale gas in Qiangtang Basin are forecast and analyzed.It is relatively favorable in a tectonic setting and indication of oil and gas,shale maturity,sedimentary thickness and gypsum-salt beds,and in terms of mineral association for shale gas accumulation.But the challenge lies in overcoming the harsh natural conditions which contributes to great difficulties in ground engineering and exploration,and high exploration costs.展开更多
Coal roadway support is the foundation and strong guarantee of safe coal production. With the FLAC3D numerical simulation, the roadway fulllength anchor support mechanism was studied, and the full-length anchor forcet...Coal roadway support is the foundation and strong guarantee of safe coal production. With the FLAC3D numerical simulation, the roadway fulllength anchor support mechanism was studied, and the full-length anchor forcetransferring mechanism and stressfield distribution formed by roadway surrounding rocks were analyzed, which will provide a scientific basis for a support technology in large-section roadways under complicated geological conditions and lay a foundation for the popularization and application of a full-length anchor support system under special geological conditions.展开更多
The goal of this study is to determine the geometrical and geotechnical characteristics of landslides under various geological conditions using detailed field surveys, laboratory soil tests and precipitation records. ...The goal of this study is to determine the geometrical and geotechnical characteristics of landslides under various geological conditions using detailed field surveys, laboratory soil tests and precipitation records. Three study areas are selected to consider different rocks, including gneiss in Jangheung, granite in Sangju and sedimentary rocks in Pohang, South Korea. Many landslides have occurred in these three areas during the rainy season.Precipitation records indicate that landslides occurring in the gneiss area of Jangheung and granite area of Sangju may be influenced by the hourly rainfall intensity rather than cumulative rainfall.However, landslides occurring in the sedimentary rock area of Pohang may be influenced by hourly rainfall intensity and cumulative rainfall. To investigate the factors that influence these types of landslides, a detailed landslide survey was performed and a series of laboratory soil tests were conducted.According to the detailed field survey, most landslides occurred on the flanks of mountain slopes, and the slope inclination where they occurred mostly ranged from 26 to 30 degrees, regardless of the geological conditions. The landslide in the gneiss area of Jangheung is larger than the landslides in the granite area of Sangju and sedimentary rock area of Pohang.Particularly, the landslide in the sedimentary rock area is shorter and shallower than the landslides in the gneiss and granite areas. Thus, the shape and size of the landslide are clearly related to the geological conditions. According to the integrated soil property and landslide occurrence analyses results, the average dry unit weight of the soils from the landslide sites is smaller than that of the soils obtained from the nonlandslide site. The average coefficient of permeability of soils obtained from the landslide sites is greater than that of soils obtained from the non-landslide sites with the same geology. These results indicate that the soils from the landslide sites are more poorly graded or looser than the soils from the non-landslide sites.展开更多
By combining the practices of deep mine mining in Changguang Mine field and using the Universal Distinct Element Code 3 0(UDEC3 0) numerical computing method, the distribution characteristics of deformation field and ...By combining the practices of deep mine mining in Changguang Mine field and using the Universal Distinct Element Code 3 0(UDEC3 0) numerical computing method, the distribution characteristics of deformation field and stress field as well as the surrounding rock deformation regularity of soft rock roadway are analyzed under extremely complicated geological conditions, a technical principle of bolting to control the surrounding rock of roadway is put forward. And also using a dynamic control for surrounding rocks designing method, the supporting parameters and implement plan are rationally determined. The experimental tests have obtained a good controlling result of surrounding rock.展开更多
There is a great difference between the distribution and evolvement characteristics of slope geological hazard in the same geographical location and climatic conditions,taking the similar structural-genetic connection...There is a great difference between the distribution and evolvement characteristics of slope geological hazard in the same geographical location and climatic conditions,taking the similar structural-genetic connection in Wudongde reservoir area of Jinshajiang River valley for example. In all engineering geological conditions,the chronologic age and attitude of strata,and the lithologic association factors control the distributions and evolvement characteristics of slope geological hazard in the studied area. The study shows that the slopes in geological evolution are in different stages. The conclusion helps to understand the types and the intensity of geological disasters.展开更多
Many researchers worked a lot on geologic conditions for lateral sealing of faults,but none of their studies took the effect of internal structures of fault zones on the lateral sealing capacity of faults.Therefore,th...Many researchers worked a lot on geologic conditions for lateral sealing of faults,but none of their studies took the effect of internal structures of fault zones on the lateral sealing capacity of faults.Therefore,the lateral sealing of active faults has rarely been discussed.In this paper,based on the analysis of the composition and structure characteristics of fault fillings,the geological conditions for lateral sealing of active faults and relevant research method were discussed in reference to the lateral sealing mechanisms of inactive fault rocks.It is shown that,in order to satisfy geologically the lateral sealing of active faults,the faults should be antithetic and the faulted strata should be mainly composed of mudstone,so that the displacement pressure of fault fillings is higher than or equal to that of reservoir rocks in oil and gas migration block.Then,a research method for the lateral sealing of active faults was established by comparing the displacement pressure of fillings in the fault with that of reservoir rocks in oil and gas migration block.This method was applied to three antithetic faults(F1,F2 and F3)in No.1 structure of the Nanpu Sag,Bohai Bay Basin.As revealed,the fillings of these three active faults were mostly argillaceous at the stage of natural gas accu-mulation(the late stage of Neogene Minghuazhen Fm sedimentation),and their displacement pressures were higher than that of reservoir rocks in the first member of Paleogene Dongying Fm(F1 and F3)and the Neogene Guantao Fm(F2).Accordingly,they are laterally sealed for natural gas,which is conducive to the accumulation and preservation of natural gas.Industrial gas flow has been produced from the first member of Paleogene Dongying Fm in Well Np101,the Guantao Fm in Well Np1-2 and the first member of Paleogene Dongying Fm in Well Np1,which is in agreement with the analysis result.It is verified that this method is feasible for investigating the lateral sealing of active faults.展开更多
This foundation pit project is located in the flood plain area of the Yangtze River in Hexi, Nanjing, with complicated geological conditions, high underground water level, ultra-thick sand layer and rock entry. The fo...This foundation pit project is located in the flood plain area of the Yangtze River in Hexi, Nanjing, with complicated geological conditions, high underground water level, ultra-thick sand layer and rock entry. The foundation pit adopts a 50m-deep TRD underground water soil mixing wall and a 15m-deep MJS construction pile as the waterproof curtain outside the foundation pit. This paper discusses the construction technology of TRD combined with MJS waterproof curtain and the technical measures such as design optimization, equipment configuration, main process parameters, construction points, construction difficulties and treatment measures in the construction process, which largely solves the difficult problems of crossing ultra-deep fine sand layer, gravel layer and eventually entering rock, and the construction is difficult, and achieves good construction effect.展开更多
The further development of society depends on the support of energy. Based on China's economic construction system, the importance of coal mines can not be ignored. With the increasing demand for coal, the demand ...The further development of society depends on the support of energy. Based on China's economic construction system, the importance of coal mines can not be ignored. With the increasing demand for coal, the demand for mining is also increasing. Therefore, it is necessary to maintain the safety and stability of coal mining with the help of tunneling support technology, and complete the core goal of coal mining under complex geological conditions. Based on this, this paper explores the efficient coal mine excavation support technology in complex terrain, hoping to provide some feasible reference opinions for the majority of colleagues.展开更多
EPB TBMs(Earth pressure balance Tunneling Boring Machines) are extensively used in tunneling constructions because of its high efficiency and low disturbance on structures above ground. It is critically significant to...EPB TBMs(Earth pressure balance Tunneling Boring Machines) are extensively used in tunneling constructions because of its high efficiency and low disturbance on structures above ground. It is critically significant to predict the thrust acting on TBMs under different geological conditions for both the design of power system and the control of tunneling process. The interaction between the cutterhead and the ground is the core of excavation, through which geological conditions determine the thrust re-quirement combined with operating status and structural characteristics. This paper conducted a mechanical decoupling analysis to obtain a basic expression of the cutterhead-ground interactive stress. Then more engineering factors(such as cutterhead topological structure, underground overburden, thrusts on other parts, etc.) were further considered to establish a predicting model for the total thrust acting on a machine during tunneling. Combined with three subway projects under different geological conditions in China, the model was verified and used to analyze how geological, operating and structural parameters influence the acting thrust.展开更多
The Meso-Neoproterozoic strata are wildly distributed in North China Craton(NCC),of which Changchengian strata are most widely developed.Taking Changchengian strata in south margin of NCC as the study object,and combi...The Meso-Neoproterozoic strata are wildly distributed in North China Craton(NCC),of which Changchengian strata are most widely developed.Taking Changchengian strata in south margin of NCC as the study object,and combined with comprehensive analysis of isotopic chronology and petrology,it can be concluded that the Xiong'er rift is a plume rift which responds to breakup of Columbia supercontinent.Seismic data shows that Changchengian rifts are developed in the Qinshui Basin and the southern part of Ordos Basin covered by Phanerozoic strata,respectively are large-scale graben rifts and half-graben rifts.Aero magnetic data indicates that a NE-trending rift is developed in the west of the Xiong'er rift,and the Qinshui Basin rift is the extension of the north branch of the Xiong'er rift.The filling process of Changchengian rifts can be divided into four stages:the early rifting stage developing thick andesitic volcanic rocks,the late rifting stage developing large suite of coarse clastic sedimentary rocks,the depression stage developing fine clastic rocks,and the epeiric sea stage developing carbonate rocks.The dark argillaceous rocks are developed in Cuizhuang Formation and Chenjiajian Formation during the depression stage,and the black shale in Cuizhuang Formation is the effective source rocks.The bitume is filled in fractures of dolomite in Luoyukou Formation,as well as dissolution pores and large caves in Longjiayuan Formation.The argillaceous sandstone and muddy limestone of Lower Cambrian is the effective cap rocks,which can form an potential accumulation assemblage of Changchengian strata with underlying source rocks of Cuizhuang Formation and reservoirs of Luoyu Group,and this assemblage may be still effective at present.展开更多
Rock fracture toughness is a critical parameter for optimizing reservoir stimulation during deep resource extraction.This index characterizes the in situ resistance of rocks to fracture and is affected by high tempera...Rock fracture toughness is a critical parameter for optimizing reservoir stimulation during deep resource extraction.This index characterizes the in situ resistance of rocks to fracture and is affected by high temperature,in situ stress,thermal shock,and chemical corrosion,etc.This review comprehensively examines research on rock fracture properties in situ environments over the past 20 years,analyses the influences of various environmental factors on rock fracture,and draws the following conclusions:(i)Environmental factors can significantly affect rock fracture toughness through changing the internal microstructure and grain composition of rocks;(ii)While high temperature is believed to reduce the rock strength,several studies have observed an increase in rock fracture toughness with increasing temperature,particularly in the range between room temperature and 200℃;(iii)In addition to a synergistic increase in fracture toughness induced by both high temperature and high in situ stress,there is still a competing effect between the increase induced by high in situ stress and the decrease induced by high temperature;(iv)Thermal shock from liquid nitrogen cooling,producing high temperature gradients,can surprisingly increase the fracture toughness of some rocks,especially at initial temperatures between room temperature and 200℃;and(v)Deterioration of rock fracture toughness occurs more rapidly in acidic environments than that in alkaline environments.In addition,this review identified current research trends and suggested some potential directions to provide suggestions for deep subsurface resource extraction.展开更多
The water depth in Nansha（南沙） waters,which is located in the southern South China Sea,varies from 200 to 2 500 m,with a deep-water（500 m） area of 500 000 km2.In this region,there are many depositional basins wit...The water depth in Nansha（南沙） waters,which is located in the southern South China Sea,varies from 200 to 2 500 m,with a deep-water（500 m） area of 500 000 km2.In this region,there are many depositional basins with various structural features,prone to the accumulation of organic material.The temperature and pressure conditions in the deep-water environment are suitable for the preservation of gas hydrate.At several sites,we have recognized bottom-simulating reflectors（BSRs） from seismic data.Regional geology analyses show that the Nansha waters may have abundant gas hy-drate prospects,especially in localities such as the Nansha trough and other deep-water basins of the central Nansha waters.展开更多
Deep Underground Science and Engineering(DUSE)is pleased to present this special issue on Groundwater and Stability in Deep Mining.As mining operations progress to greater depths to meet the growing global demand for ...Deep Underground Science and Engineering(DUSE)is pleased to present this special issue on Groundwater and Stability in Deep Mining.As mining operations progress to greater depths to meet the growing global demand for mineral resources and energy,the challenges associated with groundwater control and rock mass stability have grown increasingly critical.These challenges are exacerbated by complex geological conditions,structural heterogeneity,and intense mining-induced disturbances.This special issue seeks to address these challenges by showcasing cutting-edge research and technological advancements in the field.展开更多
China’s energy resource endowment is characterized by being“poor in oil,scarce in gas,and rich in coal”,a fundamental national condition that determines the uniqueness of China’s energy strategy.At the beginning o...China’s energy resource endowment is characterized by being“poor in oil,scarce in gas,and rich in coal”,a fundamental national condition that determines the uniqueness of China’s energy strategy.At the beginning of the 20th century,foreign experts and scholars generally concluded and claimed that China was an“oil-poor country”lacking the geological conditions for hydrocarbon formation.展开更多
In recent years,digital twin technology has gained significant attention and application in the engineering construction field in China.Its real-time feedback function has brought more standardized construction operat...In recent years,digital twin technology has gained significant attention and application in the engineering construction field in China.Its real-time feedback function has brought more standardized construction operations to various engineering construction and maintenance processes.In this context,this paper analyzes the specific application of digital twin technology in hydraulic engineering based on its foundations.Taking the reinforcement and anti-seepage digital twin application of a certain embankment section as an example,it explores the reinforcement and anti-seepage construction effects of embankment engineering with the involvement of digital twin technology under complex hydrogeological conditions.The research shows that this technology can significantly improve the control accuracy of slurry diffusion,the identification ability of seepage risks,and the adaptability of engineering construction.Its application provides a replicable digital solution for the governance model of hydraulic engineering.展开更多
The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass ...The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass was established to discuss the reasonable supporting time. Resuhs show that supporting after suitable stress and displacement release can benefit for the long-term stability of surrounding rock.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52378392,52408356)Foal Eagle Program Youth Top-notch Talent Project of Fujian Province,China(Grant No.00387088).
文摘Current machine learning models for predicting geological conditions during earth pressure balance(EPB)shield tunneling predominantly rely on accurate geological conditions as model label inputs.This study introduces an innovative approach for the real-time prediction of geological conditions in EPB shield tunneling by utilizing an unsupervised incremental learning model that integrates deep temporal clustering(DTC)with elastic weight consolidation(EWC).The model was trained and tested using data from an EPB shield tunneling project in Nanjing,China.Results demonstrate that the DTC model outperforms nine comparison models by clustering the entire dataset into four distinct groups representing various geological conditions without requiring labeled data.Additionally,integrating EWC into the DTC model significantly enhances its continuous learning capabilities,enabling automatic parameter updates with incoming data and facilitating the real-time recognition of geological conditions.Feature importance was evaluated using the feature elimination method and the Shapley additive explanations(SHAP)method,underscoring the critical roles of earth chamber pressure and cutterhead rotation speed in predicting geological conditions.The proposed EWC-DTC model demonstrates practical utility for EPB shield tunneling in complex environments.
基金supported by the project of the China Geological Survey for shale gas in Southern China(DD20221852)the National Natural Science Foundation of China(42242010,U2244208)。
文摘China is home to shales of three facies:Marine shale,continental shale,and marine-continental transitional shale.Different types of shale gas are associated with significantly different formation conditions and major controlling factors.This study compared the geological characteristics of various shales and analyzed the influences of different parameters on the formation and accumulation of shale gas.In general,shales in China’s several regions exhibit high total organic carbon(TOC)contents,which lays a sound material basis for shale gas generation.Marine strata generally show high degrees of thermal evolution.In contrast,continental shales manifest low degrees of thermal evolution,necessitating focusing on areas with relatively high degrees of thermal evolution in the process of shale gas surveys for these shales.The shales of the Wufeng and Silurian formations constitute the most favorable shale gas reservoirs since they exhibit the highest porosity among the three types of shales.These shales are followed by those in the Niutitang and Longtan formations.In contrast,the shales of the Doushantuo,Yanchang,and Qingshankou formations manifest low porosities.Furthermore,the shales of the Wufeng and Longmaxi formations exhibit high brittle mineral contents.Despite a low siliceous mineral content,the shales of the Doushantuo Formation feature a high carbonate mineral content,which can increase the shales’brittleness to some extent.For marine-continental transitional shales,where thin interbeds of tight sandstone with unequal thicknesses are generally found,it is recommended that fracturing combined with drainage of multiple sets of lithologic strata should be employed to enhance their shale gas production.
文摘Almost all the coal is produced from open cut mines in Indonesia. As a consequence of open cut mine application, a great deal of coal is left out in the highwalls of the mined-out pits. Highwall mining systems can be used to recover this coal. The use of highwall mining systems has increasingly come into play in the US and Australia. However, it is not common in Indonesia. Moreover, Indonesia coal measure is categorized as weak geological condition. Some problems are likely to arise during the application of the highwall mining system for example instability of openings and highwalls due to the roof and pillar failures. Therefore, study of highwall mining system application in Indonesia is needed in order to increase the recovery rate of coal mining in Indonesia. This paper described the characteristics of the highwa!l mining system and discussed the appropriate highwall mining system application in weak geological condition, Indonesia. From the results of a series of laboratory tests and numerical analyses, it can be concluded that the stability of pillars and mine openings in auger mining systems is much higher than that in CHM and an auger mining system is suitable for such as very weak/poor strata conditions. Moreover, the application of backfilling system is very effective for improvement of the stability of pillar and openings.
基金the National Natural Science Foundation of China(Nos.41906188,41806057,41776081)the National Marine Geology Project of China(Nos.DD20160147,DD20190365)+1 种基金the National Program on Global Change and Air-Sea Interaction(No.GASI-GEOGE-02)the Special Fund for the Taishan Scholar Program of Shandong Province(No.ts201511061)。
文摘The South Yellow Sea Basin(SYSB) has multiple sets of proven source rocks and good hydrocarbon prospects,but no industrial oil and gas has been explored at present.To solve this puzzle for petroleum geologists,we systematically investigated the marine hydrocarbon geological conditions based on cores and testing data from borehole CSDP-2,the first exploration well with continuous coring in SYSB.The qualities of source rocks are evaluated in detail according to organic matter abundance,type,and maturity.The reservoir characterization mainly includes porosity,permeability,and reservoir space.Displacement pressure test and stratum thickness are the main foundations for defining the caprocks.Then,the oil-source rock correlation in the Permian and stratum model are analyzed to determine the favorable source-reservoir-caprock assemblages.The results show that three sets of effective source rocks(the Lower Triassic,Upper Permian,and Lower Permian),two sets of tight sandstone re servoirs(the Upper Permian and Lower Silurian-Upper Devonian),and two sets of caprocks(the Lower Triassic and Carboniferous) combine to constitute the hydrocarbon reservoir-forming as se mblages of "lower-ge neration and upper-accumlation" and "self-generation and self-accumlation",thus laying a solid foundation for promising petroleum prospects.The three sets of marine source rocks are characterized by successive generation and expulsion stages,which guarantees multistage hydrocarbon accumulation.Another three sets of continental source rocks distributed across the Middle Jurassic,Upper Cretaceous,and Paleogene depression areas,especially in the Northern Depression,may supplement some hydrocarbons for the Central Uplift through faults and the Indosinian unconformity.The favorable Permian exploration strata have been identified in the Central Uplift of SYSB.First,the Lower Permian and Upper Permian source rocks with high organic matter abundance and high thermal maturity supply sufficient hydrocarbons.Secondly,the interbedding relationship between the source rocks and sandstones in the Upper Permian strata ensures that hydrocarbons have been migrated into the nearby Upper Permian sandstones,reflecting near-source hydrocarbon accumulation.Finally,the good sealing property of the Lower Triassic Qinglong Formation caprocks plays an indispensable role in hydrocarbon preservation of the Permian reservoirs.This conclusion is supported by direct oil shows,gas logging anomalous layers,and hydrocarbon-bearing fluid inclusions.
基金co-funded by National Science and Technology Major Special Project (Grant No.2011ZX05018-001 and 2011ZX05028-002)PetroChina Co. Ltd. Project (Grant No.2011D-5002-02, 2014E-050202)
文摘The presence of shale gas has been confirmed in almost every marine shale distribution area in North America.Formation conditions of shale gas in China are the most favorable for marine,organic-rich shale as well.But there has been little research focusing on shale gas in Qiangtang Basin,Qinghai-Tibet Plateau,where a lot of Mesozoic marine shale formations developed.Based on the survey results of petroleum geology and comprehensive test analysis data for Qinghai-Tibet Plateau,for the first time,this paper discusses characteristics of sedimentary development,thickness distribution,geochemistry,reservoir and burial depth of organic-rich shale,and geological conditions for shale gas formation in Qiangtang Basin.There are four sets of marine shale strata in Qiangtang Basin including Upper Triassic Xiaochaka Formation （T3x）,Middle Jurassic Buqu Formation （J2b）,Xiali Formation （J2x） and Upper Jurassic Suowa Formation （J3s）,the sedimentary types of which are mainly bathyal-basin facies,open platform-platform margin slope facies,lagoon and tidal-fiat facies,as well as delta facies.By comparing it with the indicators of gas shale in the main U.S.basins,it was found that the four marine shale formations in Qiangtang Basin constitute a multi-layer distribution of organic-rich shale,featuring a high degree of thickness and low abundance of organic matter,high thermal evolution maturity,many kinds of brittle minerals,an equivalent content of quartz and clay minerals,a high content of feldspar and low porosity,which provide basic conditions for an accumulation of shale gas resources.Xiaochaka Formation shale is widely distributed,with big thickness and the best gas generating indicators.It is the main gas source layer.Xiali Formation shale is of intermediate thickness and coverage area,with relatively good gas generating indicators and moderate gas formation potential.Buqu Formation shale and Suowa Formation shale are of relatively large thickness,and covering a small area,with poor gas generating indicators,and limited gas formation potential.The shale gas geological resources and technically recoverable resources were estimated by using geologic analogy method,and the prospective areas and potentially favorable areas for Mesozoic marine shale gas in Qiangtang Basin are forecast and analyzed.It is relatively favorable in a tectonic setting and indication of oil and gas,shale maturity,sedimentary thickness and gypsum-salt beds,and in terms of mineral association for shale gas accumulation.But the challenge lies in overcoming the harsh natural conditions which contributes to great difficulties in ground engineering and exploration,and high exploration costs.
基金Supported bythe National Natural Science Foundation of China （50904024） the State Key Laboratory Research Fund of Coal Resources and Mine Safety of China University of Mining ＆ Technology （10KF02） the Doctoral Fund of Henan Polytechnic University （B2009-66）
文摘Coal roadway support is the foundation and strong guarantee of safe coal production. With the FLAC3D numerical simulation, the roadway fulllength anchor support mechanism was studied, and the full-length anchor forcetransferring mechanism and stressfield distribution formed by roadway surrounding rocks were analyzed, which will provide a scientific basis for a support technology in large-section roadways under complicated geological conditions and lay a foundation for the popularization and application of a full-length anchor support system under special geological conditions.
基金supported by the Basic Research Project (Grant No. 15-3413) of the Korea Institute of Geoscience and Mineral Resources (KIGAM)funded by the Ministry of Science, ICT and Future Planning of Korea
文摘The goal of this study is to determine the geometrical and geotechnical characteristics of landslides under various geological conditions using detailed field surveys, laboratory soil tests and precipitation records. Three study areas are selected to consider different rocks, including gneiss in Jangheung, granite in Sangju and sedimentary rocks in Pohang, South Korea. Many landslides have occurred in these three areas during the rainy season.Precipitation records indicate that landslides occurring in the gneiss area of Jangheung and granite area of Sangju may be influenced by the hourly rainfall intensity rather than cumulative rainfall.However, landslides occurring in the sedimentary rock area of Pohang may be influenced by hourly rainfall intensity and cumulative rainfall. To investigate the factors that influence these types of landslides, a detailed landslide survey was performed and a series of laboratory soil tests were conducted.According to the detailed field survey, most landslides occurred on the flanks of mountain slopes, and the slope inclination where they occurred mostly ranged from 26 to 30 degrees, regardless of the geological conditions. The landslide in the gneiss area of Jangheung is larger than the landslides in the granite area of Sangju and sedimentary rock area of Pohang.Particularly, the landslide in the sedimentary rock area is shorter and shallower than the landslides in the gneiss and granite areas. Thus, the shape and size of the landslide are clearly related to the geological conditions. According to the integrated soil property and landslide occurrence analyses results, the average dry unit weight of the soils from the landslide sites is smaller than that of the soils obtained from the nonlandslide site. The average coefficient of permeability of soils obtained from the landslide sites is greater than that of soils obtained from the non-landslide sites with the same geology. These results indicate that the soils from the landslide sites are more poorly graded or looser than the soils from the non-landslide sites.
文摘By combining the practices of deep mine mining in Changguang Mine field and using the Universal Distinct Element Code 3 0(UDEC3 0) numerical computing method, the distribution characteristics of deformation field and stress field as well as the surrounding rock deformation regularity of soft rock roadway are analyzed under extremely complicated geological conditions, a technical principle of bolting to control the surrounding rock of roadway is put forward. And also using a dynamic control for surrounding rocks designing method, the supporting parameters and implement plan are rationally determined. The experimental tests have obtained a good controlling result of surrounding rock.
文摘There is a great difference between the distribution and evolvement characteristics of slope geological hazard in the same geographical location and climatic conditions,taking the similar structural-genetic connection in Wudongde reservoir area of Jinshajiang River valley for example. In all engineering geological conditions,the chronologic age and attitude of strata,and the lithologic association factors control the distributions and evolvement characteristics of slope geological hazard in the studied area. The study shows that the slopes in geological evolution are in different stages. The conclusion helps to understand the types and the intensity of geological disasters.
基金Project of National Natural Science Foundation of China“Main controlling factors of oil seeping in hydraulic fracturing of fault rock and prediction of tensile fracture pressure”(No:41372154).
文摘Many researchers worked a lot on geologic conditions for lateral sealing of faults,but none of their studies took the effect of internal structures of fault zones on the lateral sealing capacity of faults.Therefore,the lateral sealing of active faults has rarely been discussed.In this paper,based on the analysis of the composition and structure characteristics of fault fillings,the geological conditions for lateral sealing of active faults and relevant research method were discussed in reference to the lateral sealing mechanisms of inactive fault rocks.It is shown that,in order to satisfy geologically the lateral sealing of active faults,the faults should be antithetic and the faulted strata should be mainly composed of mudstone,so that the displacement pressure of fault fillings is higher than or equal to that of reservoir rocks in oil and gas migration block.Then,a research method for the lateral sealing of active faults was established by comparing the displacement pressure of fillings in the fault with that of reservoir rocks in oil and gas migration block.This method was applied to three antithetic faults(F1,F2 and F3)in No.1 structure of the Nanpu Sag,Bohai Bay Basin.As revealed,the fillings of these three active faults were mostly argillaceous at the stage of natural gas accu-mulation(the late stage of Neogene Minghuazhen Fm sedimentation),and their displacement pressures were higher than that of reservoir rocks in the first member of Paleogene Dongying Fm(F1 and F3)and the Neogene Guantao Fm(F2).Accordingly,they are laterally sealed for natural gas,which is conducive to the accumulation and preservation of natural gas.Industrial gas flow has been produced from the first member of Paleogene Dongying Fm in Well Np101,the Guantao Fm in Well Np1-2 and the first member of Paleogene Dongying Fm in Well Np1,which is in agreement with the analysis result.It is verified that this method is feasible for investigating the lateral sealing of active faults.
文摘This foundation pit project is located in the flood plain area of the Yangtze River in Hexi, Nanjing, with complicated geological conditions, high underground water level, ultra-thick sand layer and rock entry. The foundation pit adopts a 50m-deep TRD underground water soil mixing wall and a 15m-deep MJS construction pile as the waterproof curtain outside the foundation pit. This paper discusses the construction technology of TRD combined with MJS waterproof curtain and the technical measures such as design optimization, equipment configuration, main process parameters, construction points, construction difficulties and treatment measures in the construction process, which largely solves the difficult problems of crossing ultra-deep fine sand layer, gravel layer and eventually entering rock, and the construction is difficult, and achieves good construction effect.
文摘The further development of society depends on the support of energy. Based on China's economic construction system, the importance of coal mines can not be ignored. With the increasing demand for coal, the demand for mining is also increasing. Therefore, it is necessary to maintain the safety and stability of coal mining with the help of tunneling support technology, and complete the core goal of coal mining under complex geological conditions. Based on this, this paper explores the efficient coal mine excavation support technology in complex terrain, hoping to provide some feasible reference opinions for the majority of colleagues.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11127202 & 11302146)
文摘EPB TBMs(Earth pressure balance Tunneling Boring Machines) are extensively used in tunneling constructions because of its high efficiency and low disturbance on structures above ground. It is critically significant to predict the thrust acting on TBMs under different geological conditions for both the design of power system and the control of tunneling process. The interaction between the cutterhead and the ground is the core of excavation, through which geological conditions determine the thrust re-quirement combined with operating status and structural characteristics. This paper conducted a mechanical decoupling analysis to obtain a basic expression of the cutterhead-ground interactive stress. Then more engineering factors(such as cutterhead topological structure, underground overburden, thrusts on other parts, etc.) were further considered to establish a predicting model for the total thrust acting on a machine during tunneling. Combined with three subway projects under different geological conditions in China, the model was verified and used to analyze how geological, operating and structural parameters influence the acting thrust.
基金The work was supported by the National Key Research and Development Program of China(No.2016YFC0601002)Frontier Basic Research Program of PetroChina Research Institute of Petroleum Exploration and Development(No.2015yj-09).
文摘The Meso-Neoproterozoic strata are wildly distributed in North China Craton(NCC),of which Changchengian strata are most widely developed.Taking Changchengian strata in south margin of NCC as the study object,and combined with comprehensive analysis of isotopic chronology and petrology,it can be concluded that the Xiong'er rift is a plume rift which responds to breakup of Columbia supercontinent.Seismic data shows that Changchengian rifts are developed in the Qinshui Basin and the southern part of Ordos Basin covered by Phanerozoic strata,respectively are large-scale graben rifts and half-graben rifts.Aero magnetic data indicates that a NE-trending rift is developed in the west of the Xiong'er rift,and the Qinshui Basin rift is the extension of the north branch of the Xiong'er rift.The filling process of Changchengian rifts can be divided into four stages:the early rifting stage developing thick andesitic volcanic rocks,the late rifting stage developing large suite of coarse clastic sedimentary rocks,the depression stage developing fine clastic rocks,and the epeiric sea stage developing carbonate rocks.The dark argillaceous rocks are developed in Cuizhuang Formation and Chenjiajian Formation during the depression stage,and the black shale in Cuizhuang Formation is the effective source rocks.The bitume is filled in fractures of dolomite in Luoyukou Formation,as well as dissolution pores and large caves in Longjiayuan Formation.The argillaceous sandstone and muddy limestone of Lower Cambrian is the effective cap rocks,which can form an potential accumulation assemblage of Changchengian strata with underlying source rocks of Cuizhuang Formation and reservoirs of Luoyu Group,and this assemblage may be still effective at present.
基金supported by the National Natural Science Foundation of China(Grant No.12172240).
文摘Rock fracture toughness is a critical parameter for optimizing reservoir stimulation during deep resource extraction.This index characterizes the in situ resistance of rocks to fracture and is affected by high temperature,in situ stress,thermal shock,and chemical corrosion,etc.This review comprehensively examines research on rock fracture properties in situ environments over the past 20 years,analyses the influences of various environmental factors on rock fracture,and draws the following conclusions:(i)Environmental factors can significantly affect rock fracture toughness through changing the internal microstructure and grain composition of rocks;(ii)While high temperature is believed to reduce the rock strength,several studies have observed an increase in rock fracture toughness with increasing temperature,particularly in the range between room temperature and 200℃;(iii)In addition to a synergistic increase in fracture toughness induced by both high temperature and high in situ stress,there is still a competing effect between the increase induced by high in situ stress and the decrease induced by high temperature;(iv)Thermal shock from liquid nitrogen cooling,producing high temperature gradients,can surprisingly increase the fracture toughness of some rocks,especially at initial temperatures between room temperature and 200℃;and(v)Deterioration of rock fracture toughness occurs more rapidly in acidic environments than that in alkaline environments.In addition,this review identified current research trends and suggested some potential directions to provide suggestions for deep subsurface resource extraction.
基金supported by the National Basic Research Programs of China (973 Programs) (Nos. 2009CB2194 and 2007CB411700)the National Natural Science Fundation of China (Nos. 40976029 and 40676039)+2 种基金the Major Knowledge Innovation Program of Chinese Academy of Sciences (No. kzcx2-yw-203-01)the National Program of Sustaining Science and Technology (No. 2006BAB19B00)the Ministry of Land and Resources, China (Nos. GT-YQ-QQ-2008-1-02 and 2009GYXQ06)
文摘The water depth in Nansha（南沙） waters,which is located in the southern South China Sea,varies from 200 to 2 500 m,with a deep-water（500 m） area of 500 000 km2.In this region,there are many depositional basins with various structural features,prone to the accumulation of organic material.The temperature and pressure conditions in the deep-water environment are suitable for the preservation of gas hydrate.At several sites,we have recognized bottom-simulating reflectors（BSRs） from seismic data.Regional geology analyses show that the Nansha waters may have abundant gas hy-drate prospects,especially in localities such as the Nansha trough and other deep-water basins of the central Nansha waters.
文摘Deep Underground Science and Engineering(DUSE)is pleased to present this special issue on Groundwater and Stability in Deep Mining.As mining operations progress to greater depths to meet the growing global demand for mineral resources and energy,the challenges associated with groundwater control and rock mass stability have grown increasingly critical.These challenges are exacerbated by complex geological conditions,structural heterogeneity,and intense mining-induced disturbances.This special issue seeks to address these challenges by showcasing cutting-edge research and technological advancements in the field.
文摘China’s energy resource endowment is characterized by being“poor in oil,scarce in gas,and rich in coal”,a fundamental national condition that determines the uniqueness of China’s energy strategy.At the beginning of the 20th century,foreign experts and scholars generally concluded and claimed that China was an“oil-poor country”lacking the geological conditions for hydrocarbon formation.
文摘In recent years,digital twin technology has gained significant attention and application in the engineering construction field in China.Its real-time feedback function has brought more standardized construction operations to various engineering construction and maintenance processes.In this context,this paper analyzes the specific application of digital twin technology in hydraulic engineering based on its foundations.Taking the reinforcement and anti-seepage digital twin application of a certain embankment section as an example,it explores the reinforcement and anti-seepage construction effects of embankment engineering with the involvement of digital twin technology under complex hydrogeological conditions.The research shows that this technology can significantly improve the control accuracy of slurry diffusion,the identification ability of seepage risks,and the adaptability of engineering construction.Its application provides a replicable digital solution for the governance model of hydraulic engineering.
文摘The methods combined by test, field monitoring and theoretical analysis were adopted to do the systemic research on the rock mass from micro-structure to macro-deformation, and rheological model of Jinchuan rock mass was established to discuss the reasonable supporting time. Resuhs show that supporting after suitable stress and displacement release can benefit for the long-term stability of surrounding rock.
