The Zagros Basin in southwestern Iran is a significant source of coal,with numerous coal mines operating in the region.Ensuring the stability of coal mines is crucial for safe and efficient mining operations.This stud...The Zagros Basin in southwestern Iran is a significant source of coal,with numerous coal mines operating in the region.Ensuring the stability of coal mines is crucial for safe and efficient mining operations.This study investigates the time-varying response of rocks and roof resistance in coal mines in the Zagros Mountains using a novel approach that combines numerical simulation,relaxation testing,and rock displacement studies.The results show that rocks exhibit significant time-dependent behavior,with changes in rock mechanical properties over time.A comprehensive viscoelastic-plastic model is devel-oped to accurately describe the time-varying strain-softening response of rocks and simulate laboratory tests.The model integrates the Burgers and strain-softening models,simulating stress relaxation curves and rock displacement over time.The study reveals that the rock mass displays significant nonlinear behavior,with changes in rock mechanical properties over time.The findings of this study highlight the importance of considering the time-varying response of rocks and roof resistance in coal mine stability analysis.The results provide valuable insights into the time-dependent behavior of rock mass in coal mines in Iran,which can inform mining practices and mitigate potential hazards.Results in this study can contribute to developing strategies for improving roof stability and reducing the likelihood of roof collapses.展开更多
The Xialonggang Pb-Zn-Sb deposit is a newly discovered large-scale polymetallic deposit within the Tethyan Himalayan metallogenic belt.Although significant prospecting breakthroughs have been made at Xialonggang in re...The Xialonggang Pb-Zn-Sb deposit is a newly discovered large-scale polymetallic deposit within the Tethyan Himalayan metallogenic belt.Although significant prospecting breakthroughs have been made at Xialonggang in recent years,the geology and mineralization process are poorly understood.This study conducted monazite U-Pb geochronology,fluid inclusion,and O-H-S isotope of the Xialonggang Pb-Zn-Sb deposit.Analytical results indicate that the ore-forming fluids constituted a H_(2)O-NaCl-CO_(2)-CH_(4)-N_(2)system characterized by moderate temperatures(261-314℃)and moderate to low salinities(2.9-8.9 wt%NaCl eqv.).The early-stage fluids exhibited signatures close to magmatic fluids,while the late-stage fluids showed characteristics indicative of mixing between magmatic fluids and meteoric water.Sulfur isotope analysis(mainly range primarily from 1.2‰to 6.44‰,with one sphalerite up to 8.19‰)revealed that a predominantly deep-sourced sulfur composition with minor contribution from sedimentary strata.This study demonstrates that the Xialonggang Pb-Zn-Sb deposit is controlled by the NE-trending fault system.A hydrothermal circulation system driven by substantial deep-seated magmatic heat,leached materials from the surrounding strata.The hydrothermal fluids migrated upwards along the fault system,filling the NE-trending tensional fractures to form a hydrothermal vein-type Pb-Zn-Sb deposit.展开更多
＂Continuous＂ tight gas reservoirs are those reservoirs which develop in widespread tight sandstones with a continuous distribution of natural gas. In this paper, we summarize the geological features of the source ro...＂Continuous＂ tight gas reservoirs are those reservoirs which develop in widespread tight sandstones with a continuous distribution of natural gas. In this paper, we summarize the geological features of the source rocks and ＂＇continuous＂ tight gas reservoirs in the Xujiahe Formation of the middle- south transition region, Sichuan Basin. The source rocks of the Xul Member and reservoir rocks of the Xu2 Member are thick （Xul Member： 40 m, Xu2 Member： 120 m） and are distributed continuously in this study area. The results of drilled wells show that the widespread sandstone reservoirs of the Xu2 Member are charged with natural gas. Therefore, the natural gas reservoirs of the Xu2 Member in the middle-south transition region are ＂continuous＂ tight gas reservoirs. The accumulation of ＂continuous＂ tight gas reservoirs is controlled by an adequate driving force of the pressure differences between source rocks and reservoirs, which is demonstrated by a ＂one-dimensional＂ physical simulation experiment. In this simulation, the natural gas of＂continuous＂ tight gas reservoirs moves tbrward with no preferential petroleum migration pathways （PPMP）, and the natural gas saturation of＂continuous＂ tight gas reservoirs is higher than that of conventional reservoirs.展开更多
The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic–Paleozoic strata are widely distributed.The latest geophysical data were used to overcome the limitation of previous poor...The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic–Paleozoic strata are widely distributed.The latest geophysical data were used to overcome the limitation of previous poor-quality deep data.Meanwhile,the geological characteristics of hydrocarbon reservoirs in the marine Mesozoic–Paleozoic strata in the South Yellow Sea Basin were analyzed by comparing the source rocks and the reservoir and utilizing drilling and outcrop data.It is believed that the South Yellow Sea Basin roughly underwent six evolutionary stages:plate spreading,plate convergence,stable platform development,foreland basin development,faulted basin development,and depression basin development.The South Yellow Sea Basin has characteristics of a composite platform-fault depression geological structure,with a half-graben geological structure and with a ‘sandwich structure' in the vertical direction.Four sets of hydrocarbon source rocks developed – the upper Permian Longtan–Dalong formation,the lower Permian Qixia formation,the lower Silurian Gaojiabian formation,and the lower Cambrian Hetang formation/Mufushan formation,giving the South Yellow Sea Basin relatively good hydrocarbon potential.The carbonate is the main reservoir rock type in the South Yellow Sea area,and there are four carbonate reservoir types:porous dolomitic,reef-bank,weathered crust,and fractured.There are reservoir-forming horizons similar to the typical hydrocarbon reservoirs in the Yangtze land area developed in the South Yellow Sea,and there are three sets of complete source-reservoir-cap rock assemblages developed in the marine strata,with very good hydrocarbon potential.展开更多
This study presents a framework for predicting geological characteristics based on integrating a stacking classification algorithm(SCA) with a grid search(GS) and K-fold cross validation(K-CV). The SCA includes two le...This study presents a framework for predicting geological characteristics based on integrating a stacking classification algorithm(SCA) with a grid search(GS) and K-fold cross validation(K-CV). The SCA includes two learner layers: a primary learner’s layer and meta-classifier layer. The accuracy of the SCA can be improved by using the GS and K-CV. The GS was developed to match the hyper-parameters and optimise complicated problems. The K-CV is commonly applied to changing the validation set in a training set. In general, a GS is usually combined with K-CV to produce a corresponding evaluation index and select the best hyper-parameters. The torque penetration index(TPI) and field penetration index(FPI) are proposed based on shield parameters to express the geological characteristics. The elbow method(EM) and silhouette coefficient(Si) are employed to determine the types of geological characteristics(K) in a Kmeans++ algorithm. A case study on mixed ground in Guangzhou is adopted to validate the applicability of the developed model. The results show that with the developed framework, the four selected parameters, i.e. thrust, advance rate, cutterhead rotation speed and cutterhead torque, can be used to effectively predict the corresponding geological characteristics.展开更多
Based on the latest drilling, seismic and field outcrop data, the geological characteristics(e.g. strata, development and sedimentary evolution) of the southern segment of the Late Sinian–Early Cambrian Deyang–Anyue...Based on the latest drilling, seismic and field outcrop data, the geological characteristics(e.g. strata, development and sedimentary evolution) of the southern segment of the Late Sinian–Early Cambrian Deyang–Anyue rift trough in the Sichuan Basin are analyzed. First, the strata in the southern segment are complete. The first to second members of Dengying Formation(Deng 1 + Deng 2) are found with relatively stable thickness(400–550 m), and the third to fourth members(Deng 3+ Deng 4) show great thickness difference between the marginal trough and the inner trough, which is up to 250 m. The Cambrian Maidiping Formation and Qiongzhusi Formation in southern Sichuan Basin are relatively thin, with the thickness changing greatly and frequently. Second, the Deyang–Anyue rift trough extended southward during the Deng 4 period, affecting southern Sichuan Basin. Compared to the middle and northern segments of the rift trough, the southern segment is generally wide, gentle and shallow, with multiple steps, and alternating uplifts and sags, which are distributed in finger shape. Third, the Deng 1 + Deng 2 in southern Sichuan Basin records the dominance of carbonate platform and unobvious sedimentary differentiation, and the Deng 4 exhibits obvious sedimentary differentiation, namely, basin–slope–secondary slope–slope–secondary slope–platform margin–restricted platform, from the inner trough to the marginal trough. Fourth, the rift trough in southern Sichuan Basin has evolved in four stages: stabilization of Deng 1–Deng 2, initialization of Deng 3–Deng 4, filling of Maidiping–Qiongzhusi, and extinction of Canglangpu Formation.展开更多
Da Qaidam salt lake is known for its both liquid and solid boron resource.Data from previous investigation of the Da Qaidam salt lake provided a comparable framework for this study that focused on investigating the se...Da Qaidam salt lake is known for its both liquid and solid boron resource.Data from previous investigation of the Da Qaidam salt lake provided a comparable framework for this study that focused on investigating the section beneath the bottom of the perennial salt lake,including the timing,展开更多
"Golden triangle"area bordered on Yunnan-Guizhou-Guangxi was one of the most important Carlin-type gold deposits concentration areas.Deep understanding of Carlin-type gold deposits in Guizhou and Guangxi Pro..."Golden triangle"area bordered on Yunnan-Guizhou-Guangxi was one of the most important Carlin-type gold deposits concentration areas.Deep understanding of Carlin-type gold deposits in Guizhou and Guangxi Province had reached through several decades studies,but geological environment was very complex in the southeastern Yunnan,and Carlin-type gold deposits produced in the southeastern Yunnan were different from that of America,few studies were taken there.Based on a large number of field work,studies on the geological characteristics combining with geochemistry characteristics were taken,and analysis the genesis of Laozhaiwan gold deposit.The types of alteration in Laozhaiwan gold deposit were mainly silicification and pyritization,and Gold grade was high when silicification and pyritization were both occurred.It could be caculated that fluid density(g/cm3)varied from 0.7 to 4.9,salinity varied from 0.76%to 0.95%and ore-forming pressure(Pa)varied from 1.81×105 to 49.96×105 according to fluid inclusion test results,showed that Laozhaiwan gold deposit was hypabyssal hydrothermal deposit in low temperature and low salinity.According to composition of fluid inclusion analysis,combining with H-O isotope,made theδD-δ18O figure,showed that the fluid of the deposit rooted in formation water and mixed with meteoric waters later.展开更多
Potash is one of the long-term scare deposits in China,and potash prospecting has long been listed as a key brainstorm project for our nation and geological prospecting units.There have been considerable studies in se...Potash is one of the long-term scare deposits in China,and potash prospecting has long been listed as a key brainstorm project for our nation and geological prospecting units.There have been considerable studies in search for potash deposits in the Kuqa depression of the Tarim basin(Jackson et al.,1991;Gemmer et al.,2004;Vendeville,2005;Vendeville and Jackson,1992a,1992b),展开更多
To understand the shale gas reservoirs in the first member of the Permian Maokou Formation(Mao 1 Member)in Nanchuan area of the Sichuan Basin,we used outcrops,cores,mineralogical and geochemical datas,thin-section ana...To understand the shale gas reservoirs in the first member of the Permian Maokou Formation(Mao 1 Member)in Nanchuan area of the Sichuan Basin,we used outcrops,cores,mineralogical and geochemical datas,thin-section analysis,and argon-ion-polishing scanning electron microscopy results with logging and seismic attribute prediction techniques to study the sedimentary facies,source rocks,reservoir properties and types.The geological characteristics and enrichment model of shale gas reservoirs of the Mao 1 Member were revealed and are summarized as follows:(1)the Maokou Formation can be divided into four members from bottom to top.The Mao 1 Member is located in the relatively deep-water gentle slope of a carbonate platform,comprising well-developed dark-gray/grayish-black carbonaceous mudstone,calcareous mudstone,argillaceous limestone,and bioclastic limestone.Carbonaceous and calcareous mudstones,with a relatively high total organic carbon content(TOC0.5-5.1%)and moderate thermal maturity(Ro:2.0-2.3%),are potentially good hydrocarbon source rocks with possibly new type of atypical shale gas reservoir;(2)organic pores,dissolution pores,grain margin fractures,and shrinkage fractures are developed in the Mao 1 Member and may form a reservoir of a complex“poreefractureenetwork,”which is beneficial to gas storage and migration;(3)the shale gas in the Mao 1 Member has the accumulation and enrichment model of“integrated source and reservoir,continuous distribution,and structurefracture dual reservoir control”with a continuous distribution area exceeding 500 km^(2)and a geological resource volume exceeding 70 billion cubic meters;therefore,it has great exploration potential for shale gas.The research results are crucial in improving the understanding of new type of shale gas geology and guide shale gas exploration in southeastern Sichuan.展开更多
The three village Pb-Zn-Ag-Au polymetallic deposit is a newly discovered deposit in the Sanjiang area of the Ailaoshan tectonic belt. In this paper, the geological, geophysical and geochemical characteristics of the d...The three village Pb-Zn-Ag-Au polymetallic deposit is a newly discovered deposit in the Sanjiang area of the Ailaoshan tectonic belt. In this paper, the geological, geophysical and geochemical characteristics of the deposit in Sanjia village are summarized, and the ore-controlling factors and genesis of the deposit are discussed. It is preliminarily believed that the genesis type of the three village Manlong gold deposit is a mesothermal mixed metamorphic hydrothermal gold deposit controlled by the Dongsha fault. The genetic type of the lead-zinc-silver deposit in the wave section of three village mining area is the mid-low temperature hydrothermal lead-zinc-silver deposit controlled by the Gecun fault in the early Yanshanian period. It provides the prospecting direction and basis for future geological prospecting.展开更多
Chinas industrial field has developed remarkably with the steady improvement of social economy and the promotion of national science and technology level. Electrical, mechanical, military, metallurgy, chemistry and ot...Chinas industrial field has developed remarkably with the steady improvement of social economy and the promotion of national science and technology level. Electrical, mechanical, military, metallurgy, chemistry and other industrial production technologies have made great progress. With the continuous development of various industrial production activities, the demand for high-related mineral resources has also been greatly increased. It is known that lead and zinc are widely used in the above industrial production activities, so the prospecting and development of lead-zinc mines are paid more and more attention. Based on this, taking Meixian ore field in Youxi county, Fujian province as an example, this paper analyzes and sorts out the metallogenic geological characteristics and prospecting prospects of lead-zinc ore in detail, hoping to give some inspiration and reference to relevant departments.展开更多
According to the production plan of the coal mine, Nanliupan region is the lower connecting curve of the mine. The mine plans to construct two air shafts (one for the air inlet shaft and one for the air return shaft) ...According to the production plan of the coal mine, Nanliupan region is the lower connecting curve of the mine. The mine plans to construct two air shafts (one for the air inlet shaft and one for the air return shaft) in Nanliupan region. Before drilling the shaft, it is necessary to construct an air shaft inspection hole. Combining with the previous geological data, the engineering geological characteristics of the air shaft are checked in advance, and the stability of the surrounding rock of the shaft is evaluated to ensure the safety of the air shaft construction.展开更多
1 Geology Daolundaba copper polymetallic deposit occurs in West Ujimqin Banner,the Xilin Gol League of Inner Mongolia,along the west side of South part of Daxinganling ore belt,whose tectonic position just lies at the...1 Geology Daolundaba copper polymetallic deposit occurs in West Ujimqin Banner,the Xilin Gol League of Inner Mongolia,along the west side of South part of Daxinganling ore belt,whose tectonic position just lies at the junction of Siberian Block in the south part,North China Block in the north and Songliao block in the east.The Daolundaba copper polymetallic deposit is hosted by the Lower Proterozoic Baoyintu group of biotite-plagioclase gneiss(Pt1by),upper Permian Linxi formation of sandy slate(P2l),and the Hercynian Qianjinchang pluton of biotite granite.展开更多
Xiyu conglomerate is a significant and extensively distributed geological formation in western China.A clear understanding of its properties and the establishment of a classification system are essential for selecting...Xiyu conglomerate is a significant and extensively distributed geological formation in western China.A clear understanding of its properties and the establishment of a classification system are essential for selecting appropriate research methods to investigate its engineering mechanical behavior.Based on geological data from eight typical Xiyu conglomerate geological belts and seven hydropower projects,this study summarizes the main engineering geological characteristics,and analyzes the fabric characteristics of various components of the conglomerate through laboratory tests and statistical analysis.A comprehensive classification system is proposed for Xiyu conglomerate based on two key criteria:(1)grain size distribution,quantified by the d_(50)(median grain diameter),and(2)cementation type,identified via mineralogical and geochemical analysis.This system divides Xiyu conglomerate into nine distinct categories,each defined by specific engineering geological and petrofabric properties.The results reveal that,even within the same region,the grain size composition and distribution of Xiyu conglomerate are highly heterogeneous.While the chemical composition of the cementing materials is generally consistent,notable differences in cement properties arise primarily from variations in mineral content,particularly the proportion of calcareous material(dolomite,calcite,and quartz).Conglomerates with gray or grayish-blue matrices typically exhibit higher calcareous content,whereas those with earth-yellow or khaki matrices contain less calcareous material and are predominantly argillaceous-cemented.Additionally,Xiyu conglomerate shows higher porosity compared to conventional rocks.The proposed classification method based on engineering geological and fabric characteristics offers a geological basis for further determining the engineering mechanical properties of various Xiyu conglomerate types.This approach holds potential for addressing the challenges related to unclear classification and difficulty in accurately defining mechanical parameters for Xiyu conglomerate across different regions.展开更多
This work extensively investigated global tight sandstone gas,and geologically and geochemically analyzed the tight sandstone gas in China's Ordos,Sichuan,and Tarim basins.We compared typical tight sandstone gas i...This work extensively investigated global tight sandstone gas,and geologically and geochemically analyzed the tight sandstone gas in China's Ordos,Sichuan,and Tarim basins.We compared typical tight sandstone gas in China with that in North America.We proposed six conditions for the formation of China's tight sandstone gas,and illustrated the geological characteristics of tight sandstone gas.In China,gas-bearing tight sandstones were mainly deposited in continental lake deltas and marine-terrigenous facies basin environments,associated with coal-measure strata,and were mostly buried deeper than 2000 in under a formation pressure of 20-30 MPa,with pressure coefficients varying from overpressure to negative pressure.In other countries,tight gas bearing sandstones were dominantly deposited in marine to marine-terrigenous facies environments,occurred in coal-measure strata,and were mostly buried shallower than 2000 m in low-pressure systems.We systematically analyzed tight sandstone gas in the Ordos,Sichuan,and Tarim basins in terms of chemical compositions,geochemical characteristics of carbon isotopes,origins,and sources.Tight sandstone gas in China usually has a hydrocarbon content of〉95%,with CH4 content〉90%,and a generally higher dry coefficient.In the three above-mentioned large tight sandstone gas regions,δ13C1 andδJ3C2 mainly ranges from-42%o to-28%o and from-28%o to-21%o,respectively.Type III coal-measure source rocks that closely coexist with tight reservoirs are developed extensively in these gas regions.The organic petrology of source rocks and the carbon isotope compositions of gas indicate that tight sandstone gas in China is dominantly coal-derived gas generated by coal-measure strata.Our analysis of carbon isotope series shows that local isotope reversals are mainly caused by the mixing of gases of different maturities and that were generated at different stages.With increasing maturity,the reversal tendency becomes more apparent.Moreover,natural gas with medium-low maturity(e.g.,Xujiahe Formation natural gas in the Sichuan Basin)presents an apparent reversal at a low-maturity stage,a normal series at a medium-maturity stage,and a reversal tendency again at a high-maturity stage.Finally,we proposed four conditions for preferred tight sandstone gas"sweep spots,"and illustrated the recoverable reserves,proven reserves,production,and exploration prospects of tight sandstone gas.The geological and geochemical characteristics,origins,sources,and exploration potential of tight sandstone gas in China from our research will be instructive for the future evaluation,prediction,and exploration of tight sandstone gas in China and abroad.展开更多
The Shaxi porphyry copper (gold) deposits are a typical example of porphyry copper deposits associated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9 ± ...The Shaxi porphyry copper (gold) deposits are a typical example of porphyry copper deposits associated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9 ± 1.6 Ma. Geochemically, the rock is rich in alkalis (especially sodium), light rare earth elements (LREE) and large-ion lithophile elements (LILE), and has a relatively low initial strontium isotopic ratio (Isr=0.7058); thus it is the product of differentiation of crust-mantle mixing source magma. The model of alteration and mineralization zoning is similar to the Hollister (1974) diorite model. The ore fluids have a relatively high salinity and contain significant amounts of CO2, Ca2+, Na+ and ***CI?. The homogenization temperatures of fluid inclusions for the main mineralization stage range from 280 to 420°C, the δ18O values of the ore fluids vary from 3.51 to 5.52 %, the δD values are in the range between ?82.4 and ?59.8 %, the δ34S values of sulphides vary from ?0.3 to 2.49 %, and the δ13C values of CO2 in inclusions range between ?2.66 and ?6.53 %. Isotope data indicate that the hydrothermal ore fluids and ore substances of the Shaxi porphyry copper (gold) deposits were mainly derived from magmatic systems.展开更多
1 Introduction The early formation and evolution of the North China craton has been widely concerned by scientists.The Bengbu uplift belt is located in the southeast of the craton,theresearch degree of the belt is rel...1 Introduction The early formation and evolution of the North China craton has been widely concerned by scientists.The Bengbu uplift belt is located in the southeast of the craton,theresearch degree of the belt is relatively low and received increasing attention from many scholars in recent years.Through the author’s practical work and combined with展开更多
文摘The Zagros Basin in southwestern Iran is a significant source of coal,with numerous coal mines operating in the region.Ensuring the stability of coal mines is crucial for safe and efficient mining operations.This study investigates the time-varying response of rocks and roof resistance in coal mines in the Zagros Mountains using a novel approach that combines numerical simulation,relaxation testing,and rock displacement studies.The results show that rocks exhibit significant time-dependent behavior,with changes in rock mechanical properties over time.A comprehensive viscoelastic-plastic model is devel-oped to accurately describe the time-varying strain-softening response of rocks and simulate laboratory tests.The model integrates the Burgers and strain-softening models,simulating stress relaxation curves and rock displacement over time.The study reveals that the rock mass displays significant nonlinear behavior,with changes in rock mechanical properties over time.The findings of this study highlight the importance of considering the time-varying response of rocks and roof resistance in coal mine stability analysis.The results provide valuable insights into the time-dependent behavior of rock mass in coal mines in Iran,which can inform mining practices and mitigate potential hazards.Results in this study can contribute to developing strategies for improving roof stability and reducing the likelihood of roof collapses.
基金financially supported by the China Geological Survey(Grant Nos.DD20240014 and DD20243090)Central governmentguided local scientific and technological development fund project(Grant No.XZ202401YD0006-07)Ministry of Natural Resources of China(Grant No.ZKKJ202427)。
文摘The Xialonggang Pb-Zn-Sb deposit is a newly discovered large-scale polymetallic deposit within the Tethyan Himalayan metallogenic belt.Although significant prospecting breakthroughs have been made at Xialonggang in recent years,the geology and mineralization process are poorly understood.This study conducted monazite U-Pb geochronology,fluid inclusion,and O-H-S isotope of the Xialonggang Pb-Zn-Sb deposit.Analytical results indicate that the ore-forming fluids constituted a H_(2)O-NaCl-CO_(2)-CH_(4)-N_(2)system characterized by moderate temperatures(261-314℃)and moderate to low salinities(2.9-8.9 wt%NaCl eqv.).The early-stage fluids exhibited signatures close to magmatic fluids,while the late-stage fluids showed characteristics indicative of mixing between magmatic fluids and meteoric water.Sulfur isotope analysis(mainly range primarily from 1.2‰to 6.44‰,with one sphalerite up to 8.19‰)revealed that a predominantly deep-sourced sulfur composition with minor contribution from sedimentary strata.This study demonstrates that the Xialonggang Pb-Zn-Sb deposit is controlled by the NE-trending fault system.A hydrothermal circulation system driven by substantial deep-seated magmatic heat,leached materials from the surrounding strata.The hydrothermal fluids migrated upwards along the fault system,filling the NE-trending tensional fractures to form a hydrothermal vein-type Pb-Zn-Sb deposit.
基金supported by the National Major Grant of"Accumulation Law,Key Technologies and Evaluations of the Stratigraphic Reservoirs"(No.2008ZX05000-001) from the Research Institute of Petroleum Exploration & Development,PetroChina
文摘＂Continuous＂ tight gas reservoirs are those reservoirs which develop in widespread tight sandstones with a continuous distribution of natural gas. In this paper, we summarize the geological features of the source rocks and ＂＇continuous＂ tight gas reservoirs in the Xujiahe Formation of the middle- south transition region, Sichuan Basin. The source rocks of the Xul Member and reservoir rocks of the Xu2 Member are thick （Xul Member： 40 m, Xu2 Member： 120 m） and are distributed continuously in this study area. The results of drilled wells show that the widespread sandstone reservoirs of the Xu2 Member are charged with natural gas. Therefore, the natural gas reservoirs of the Xu2 Member in the middle-south transition region are ＂continuous＂ tight gas reservoirs. The accumulation of ＂continuous＂ tight gas reservoirs is controlled by an adequate driving force of the pressure differences between source rocks and reservoirs, which is demonstrated by a ＂one-dimensional＂ physical simulation experiment. In this simulation, the natural gas of＂continuous＂ tight gas reservoirs moves tbrward with no preferential petroleum migration pathways （PPMP）, and the natural gas saturation of＂continuous＂ tight gas reservoirs is higher than that of conventional reservoirs.
基金supported by the National Natural Science Foundation of China(No.41506080)the Project of China Geological Survey(Nos.DD20160152,DD20160147,and GZH200800503)+1 种基金the Project of China Ministry of Land and Resources(Nos.XQ-2005-01,and 2009GYXQ10)the Postdoctoral Innovation Fund Project of Shandong Province(No.201602004)
文摘The South Yellow Sea Basin is the main body of the lower Yangtze area in which marine Mesozoic–Paleozoic strata are widely distributed.The latest geophysical data were used to overcome the limitation of previous poor-quality deep data.Meanwhile,the geological characteristics of hydrocarbon reservoirs in the marine Mesozoic–Paleozoic strata in the South Yellow Sea Basin were analyzed by comparing the source rocks and the reservoir and utilizing drilling and outcrop data.It is believed that the South Yellow Sea Basin roughly underwent six evolutionary stages:plate spreading,plate convergence,stable platform development,foreland basin development,faulted basin development,and depression basin development.The South Yellow Sea Basin has characteristics of a composite platform-fault depression geological structure,with a half-graben geological structure and with a ‘sandwich structure' in the vertical direction.Four sets of hydrocarbon source rocks developed – the upper Permian Longtan–Dalong formation,the lower Permian Qixia formation,the lower Silurian Gaojiabian formation,and the lower Cambrian Hetang formation/Mufushan formation,giving the South Yellow Sea Basin relatively good hydrocarbon potential.The carbonate is the main reservoir rock type in the South Yellow Sea area,and there are four carbonate reservoir types:porous dolomitic,reef-bank,weathered crust,and fractured.There are reservoir-forming horizons similar to the typical hydrocarbon reservoirs in the Yangtze land area developed in the South Yellow Sea,and there are three sets of complete source-reservoir-cap rock assemblages developed in the marine strata,with very good hydrocarbon potential.
基金funded by“The Pearl River Talent Recruitment Program”of Guangdong Province in 2019(Grant No.2019CX01G338)the Research Funding of Shantou University for New Faculty Member(Grant No.NTF19024-2019).
文摘This study presents a framework for predicting geological characteristics based on integrating a stacking classification algorithm(SCA) with a grid search(GS) and K-fold cross validation(K-CV). The SCA includes two learner layers: a primary learner’s layer and meta-classifier layer. The accuracy of the SCA can be improved by using the GS and K-CV. The GS was developed to match the hyper-parameters and optimise complicated problems. The K-CV is commonly applied to changing the validation set in a training set. In general, a GS is usually combined with K-CV to produce a corresponding evaluation index and select the best hyper-parameters. The torque penetration index(TPI) and field penetration index(FPI) are proposed based on shield parameters to express the geological characteristics. The elbow method(EM) and silhouette coefficient(Si) are employed to determine the types of geological characteristics(K) in a Kmeans++ algorithm. A case study on mixed ground in Guangzhou is adopted to validate the applicability of the developed model. The results show that with the developed framework, the four selected parameters, i.e. thrust, advance rate, cutterhead rotation speed and cutterhead torque, can be used to effectively predict the corresponding geological characteristics.
基金Supported by the PetroChina Science and Technology Project (2021DJ0605,2022KT0101)the CNPC Major Science and Technology Project (2021DJ0501)。
文摘Based on the latest drilling, seismic and field outcrop data, the geological characteristics(e.g. strata, development and sedimentary evolution) of the southern segment of the Late Sinian–Early Cambrian Deyang–Anyue rift trough in the Sichuan Basin are analyzed. First, the strata in the southern segment are complete. The first to second members of Dengying Formation(Deng 1 + Deng 2) are found with relatively stable thickness(400–550 m), and the third to fourth members(Deng 3+ Deng 4) show great thickness difference between the marginal trough and the inner trough, which is up to 250 m. The Cambrian Maidiping Formation and Qiongzhusi Formation in southern Sichuan Basin are relatively thin, with the thickness changing greatly and frequently. Second, the Deyang–Anyue rift trough extended southward during the Deng 4 period, affecting southern Sichuan Basin. Compared to the middle and northern segments of the rift trough, the southern segment is generally wide, gentle and shallow, with multiple steps, and alternating uplifts and sags, which are distributed in finger shape. Third, the Deng 1 + Deng 2 in southern Sichuan Basin records the dominance of carbonate platform and unobvious sedimentary differentiation, and the Deng 4 exhibits obvious sedimentary differentiation, namely, basin–slope–secondary slope–slope–secondary slope–platform margin–restricted platform, from the inner trough to the marginal trough. Fourth, the rift trough in southern Sichuan Basin has evolved in four stages: stabilization of Deng 1–Deng 2, initialization of Deng 3–Deng 4, filling of Maidiping–Qiongzhusi, and extinction of Canglangpu Formation.
文摘Da Qaidam salt lake is known for its both liquid and solid boron resource.Data from previous investigation of the Da Qaidam salt lake provided a comparable framework for this study that focused on investigating the section beneath the bottom of the perennial salt lake,including the timing,
基金financially supported by the Program of National Natural Science Foundation of China(No.41372093No.40930423+2 种基金No.41171302)the work item of China Geological Survey(No.12120113036200)higher education quality engineering project of chalcography excellent textbook Construction(No.XJC1105)
文摘"Golden triangle"area bordered on Yunnan-Guizhou-Guangxi was one of the most important Carlin-type gold deposits concentration areas.Deep understanding of Carlin-type gold deposits in Guizhou and Guangxi Province had reached through several decades studies,but geological environment was very complex in the southeastern Yunnan,and Carlin-type gold deposits produced in the southeastern Yunnan were different from that of America,few studies were taken there.Based on a large number of field work,studies on the geological characteristics combining with geochemistry characteristics were taken,and analysis the genesis of Laozhaiwan gold deposit.The types of alteration in Laozhaiwan gold deposit were mainly silicification and pyritization,and Gold grade was high when silicification and pyritization were both occurred.It could be caculated that fluid density(g/cm3)varied from 0.7 to 4.9,salinity varied from 0.76%to 0.95%and ore-forming pressure(Pa)varied from 1.81×105 to 49.96×105 according to fluid inclusion test results,showed that Laozhaiwan gold deposit was hypabyssal hydrothermal deposit in low temperature and low salinity.According to composition of fluid inclusion analysis,combining with H-O isotope,made theδD-δ18O figure,showed that the fluid of the deposit rooted in formation water and mixed with meteoric waters later.
基金financially supported by the project of investigation and evaluation of potash deposits in the Cretaceous-Tertiary salt basin of the Tarim basin frompotash investigation project of China Geological Survey
文摘Potash is one of the long-term scare deposits in China,and potash prospecting has long been listed as a key brainstorm project for our nation and geological prospecting units.There have been considerable studies in search for potash deposits in the Kuqa depression of the Tarim basin(Jackson et al.,1991;Gemmer et al.,2004;Vendeville,2005;Vendeville and Jackson,1992a,1992b),
基金Supported by the National Major Science and Technology Project(No.2016ZX05061)the Project of Sinopec Science&Technology Department.
文摘To understand the shale gas reservoirs in the first member of the Permian Maokou Formation(Mao 1 Member)in Nanchuan area of the Sichuan Basin,we used outcrops,cores,mineralogical and geochemical datas,thin-section analysis,and argon-ion-polishing scanning electron microscopy results with logging and seismic attribute prediction techniques to study the sedimentary facies,source rocks,reservoir properties and types.The geological characteristics and enrichment model of shale gas reservoirs of the Mao 1 Member were revealed and are summarized as follows:(1)the Maokou Formation can be divided into four members from bottom to top.The Mao 1 Member is located in the relatively deep-water gentle slope of a carbonate platform,comprising well-developed dark-gray/grayish-black carbonaceous mudstone,calcareous mudstone,argillaceous limestone,and bioclastic limestone.Carbonaceous and calcareous mudstones,with a relatively high total organic carbon content(TOC0.5-5.1%)and moderate thermal maturity(Ro:2.0-2.3%),are potentially good hydrocarbon source rocks with possibly new type of atypical shale gas reservoir;(2)organic pores,dissolution pores,grain margin fractures,and shrinkage fractures are developed in the Mao 1 Member and may form a reservoir of a complex“poreefractureenetwork,”which is beneficial to gas storage and migration;(3)the shale gas in the Mao 1 Member has the accumulation and enrichment model of“integrated source and reservoir,continuous distribution,and structurefracture dual reservoir control”with a continuous distribution area exceeding 500 km^(2)and a geological resource volume exceeding 70 billion cubic meters;therefore,it has great exploration potential for shale gas.The research results are crucial in improving the understanding of new type of shale gas geology and guide shale gas exploration in southeastern Sichuan.
文摘The three village Pb-Zn-Ag-Au polymetallic deposit is a newly discovered deposit in the Sanjiang area of the Ailaoshan tectonic belt. In this paper, the geological, geophysical and geochemical characteristics of the deposit in Sanjia village are summarized, and the ore-controlling factors and genesis of the deposit are discussed. It is preliminarily believed that the genesis type of the three village Manlong gold deposit is a mesothermal mixed metamorphic hydrothermal gold deposit controlled by the Dongsha fault. The genetic type of the lead-zinc-silver deposit in the wave section of three village mining area is the mid-low temperature hydrothermal lead-zinc-silver deposit controlled by the Gecun fault in the early Yanshanian period. It provides the prospecting direction and basis for future geological prospecting.
文摘Chinas industrial field has developed remarkably with the steady improvement of social economy and the promotion of national science and technology level. Electrical, mechanical, military, metallurgy, chemistry and other industrial production technologies have made great progress. With the continuous development of various industrial production activities, the demand for high-related mineral resources has also been greatly increased. It is known that lead and zinc are widely used in the above industrial production activities, so the prospecting and development of lead-zinc mines are paid more and more attention. Based on this, taking Meixian ore field in Youxi county, Fujian province as an example, this paper analyzes and sorts out the metallogenic geological characteristics and prospecting prospects of lead-zinc ore in detail, hoping to give some inspiration and reference to relevant departments.
文摘According to the production plan of the coal mine, Nanliupan region is the lower connecting curve of the mine. The mine plans to construct two air shafts (one for the air inlet shaft and one for the air return shaft) in Nanliupan region. Before drilling the shaft, it is necessary to construct an air shaft inspection hole. Combining with the previous geological data, the engineering geological characteristics of the air shaft are checked in advance, and the stability of the surrounding rock of the shaft is evaluated to ensure the safety of the air shaft construction.
文摘1 Geology Daolundaba copper polymetallic deposit occurs in West Ujimqin Banner,the Xilin Gol League of Inner Mongolia,along the west side of South part of Daxinganling ore belt,whose tectonic position just lies at the junction of Siberian Block in the south part,North China Block in the north and Songliao block in the east.The Daolundaba copper polymetallic deposit is hosted by the Lower Proterozoic Baoyintu group of biotite-plagioclase gneiss(Pt1by),upper Permian Linxi formation of sandy slate(P2l),and the Hercynian Qianjinchang pluton of biotite granite.
基金Xinjiang Water Science and Technology Special Project,Grant/Award Numbers:XSKJ-2022-05,XSKJ-2023-30State Grid Co.,LTD.Technology Project,Grant/Award Number:5108-202218280A-2-301-XG。
文摘Xiyu conglomerate is a significant and extensively distributed geological formation in western China.A clear understanding of its properties and the establishment of a classification system are essential for selecting appropriate research methods to investigate its engineering mechanical behavior.Based on geological data from eight typical Xiyu conglomerate geological belts and seven hydropower projects,this study summarizes the main engineering geological characteristics,and analyzes the fabric characteristics of various components of the conglomerate through laboratory tests and statistical analysis.A comprehensive classification system is proposed for Xiyu conglomerate based on two key criteria:(1)grain size distribution,quantified by the d_(50)(median grain diameter),and(2)cementation type,identified via mineralogical and geochemical analysis.This system divides Xiyu conglomerate into nine distinct categories,each defined by specific engineering geological and petrofabric properties.The results reveal that,even within the same region,the grain size composition and distribution of Xiyu conglomerate are highly heterogeneous.While the chemical composition of the cementing materials is generally consistent,notable differences in cement properties arise primarily from variations in mineral content,particularly the proportion of calcareous material(dolomite,calcite,and quartz).Conglomerates with gray or grayish-blue matrices typically exhibit higher calcareous content,whereas those with earth-yellow or khaki matrices contain less calcareous material and are predominantly argillaceous-cemented.Additionally,Xiyu conglomerate shows higher porosity compared to conventional rocks.The proposed classification method based on engineering geological and fabric characteristics offers a geological basis for further determining the engineering mechanical properties of various Xiyu conglomerate types.This approach holds potential for addressing the challenges related to unclear classification and difficulty in accurately defining mechanical parameters for Xiyu conglomerate across different regions.
基金supported by the Petro China Major Scientific and Technical Project(No.:2014B-0608)the National Science and Technology Major Project of China(NO.:2011ZX5001-001)
文摘This work extensively investigated global tight sandstone gas,and geologically and geochemically analyzed the tight sandstone gas in China's Ordos,Sichuan,and Tarim basins.We compared typical tight sandstone gas in China with that in North America.We proposed six conditions for the formation of China's tight sandstone gas,and illustrated the geological characteristics of tight sandstone gas.In China,gas-bearing tight sandstones were mainly deposited in continental lake deltas and marine-terrigenous facies basin environments,associated with coal-measure strata,and were mostly buried deeper than 2000 in under a formation pressure of 20-30 MPa,with pressure coefficients varying from overpressure to negative pressure.In other countries,tight gas bearing sandstones were dominantly deposited in marine to marine-terrigenous facies environments,occurred in coal-measure strata,and were mostly buried shallower than 2000 m in low-pressure systems.We systematically analyzed tight sandstone gas in the Ordos,Sichuan,and Tarim basins in terms of chemical compositions,geochemical characteristics of carbon isotopes,origins,and sources.Tight sandstone gas in China usually has a hydrocarbon content of〉95%,with CH4 content〉90%,and a generally higher dry coefficient.In the three above-mentioned large tight sandstone gas regions,δ13C1 andδJ3C2 mainly ranges from-42%o to-28%o and from-28%o to-21%o,respectively.Type III coal-measure source rocks that closely coexist with tight reservoirs are developed extensively in these gas regions.The organic petrology of source rocks and the carbon isotope compositions of gas indicate that tight sandstone gas in China is dominantly coal-derived gas generated by coal-measure strata.Our analysis of carbon isotope series shows that local isotope reversals are mainly caused by the mixing of gases of different maturities and that were generated at different stages.With increasing maturity,the reversal tendency becomes more apparent.Moreover,natural gas with medium-low maturity(e.g.,Xujiahe Formation natural gas in the Sichuan Basin)presents an apparent reversal at a low-maturity stage,a normal series at a medium-maturity stage,and a reversal tendency again at a high-maturity stage.Finally,we proposed four conditions for preferred tight sandstone gas"sweep spots,"and illustrated the recoverable reserves,proven reserves,production,and exploration prospects of tight sandstone gas.The geological and geochemical characteristics,origins,sources,and exploration potential of tight sandstone gas in China from our research will be instructive for the future evaluation,prediction,and exploration of tight sandstone gas in China and abroad.
文摘The Shaxi porphyry copper (gold) deposits are a typical example of porphyry copper deposits associated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9 ± 1.6 Ma. Geochemically, the rock is rich in alkalis (especially sodium), light rare earth elements (LREE) and large-ion lithophile elements (LILE), and has a relatively low initial strontium isotopic ratio (Isr=0.7058); thus it is the product of differentiation of crust-mantle mixing source magma. The model of alteration and mineralization zoning is similar to the Hollister (1974) diorite model. The ore fluids have a relatively high salinity and contain significant amounts of CO2, Ca2+, Na+ and ***CI?. The homogenization temperatures of fluid inclusions for the main mineralization stage range from 280 to 420°C, the δ18O values of the ore fluids vary from 3.51 to 5.52 %, the δD values are in the range between ?82.4 and ?59.8 %, the δ34S values of sulphides vary from ?0.3 to 2.49 %, and the δ13C values of CO2 in inclusions range between ?2.66 and ?6.53 %. Isotope data indicate that the hydrothermal ore fluids and ore substances of the Shaxi porphyry copper (gold) deposits were mainly derived from magmatic systems.
基金the project "A study on gold mineralization and prospecting direction in east Anhui province" (item code: 2014-K-5)
文摘1 Introduction The early formation and evolution of the North China craton has been widely concerned by scientists.The Bengbu uplift belt is located in the southeast of the craton,theresearch degree of the belt is relatively low and received increasing attention from many scholars in recent years.Through the author’s practical work and combined with
