A giant fault-controlled oilfield has been found in the ultra-deep(greater than 6000 m) Ordovician carbonate strata in the northern Tarim Basin. It is of great significance for hydrocarbon accumulation study and oil e...A giant fault-controlled oilfield has been found in the ultra-deep(greater than 6000 m) Ordovician carbonate strata in the northern Tarim Basin. It is of great significance for hydrocarbon accumulation study and oil exploitation to determine the key oil accumulation periods. Based on detailed petrographic analysis, fluid inclusion association(FIA) in calcite samples filling in fractures from 12 wells were analyzed, and key accumulation periods of the strike-slip fault-controlled oilfield was studied by combining oil generation periods of the source rocks, formation periods of the fault and traps, and the fluid inclusion data.(1) There are multiple types of FIA, among them, two types of oil inclusions, the type with yellow fluorescence from the depression area and the type with yellow-green fluorescence from the uplift area with different maturities indicate two oil charging stages.(2) The homogenization temperature of the brine inclusions in FIA is mostly affected by temperature rises, and the minimum temperature of brine inclusions symbiotic with oil inclusions is closer to the reservoir temperature during its forming period.(3) FIA with yellow fluorescence all have homogenization temperatures below 50 ℃, while the FIA with yellow-green fluorescence have homogenization temperatures of 70–90 ℃ tested, suggesting two oil accumulation stages in Middle-Late Caledonian and Late Hercynian.(4) The Middle-Late Ordovician is the key formation period of the strike-slip fault, fracture-cave reservoir and trap there.(5) The oil generation peak of the main source rock of the Lower Cambrian is in the Late Ordovician, and the oil accumulation stage is mainly the Late Ordovician in the depression area, but is mainly the Early Permian in the uplift area. The key oil accumulation period of the strike-slip fault-controlled reservoirs is the Late Caledonian, the depression area has preserved the primary oil reservoirs formed in the Caledonian, while the uplift area has secondary oil reservoirs adjusted from the depression area during the Late Hercynian. Oil reservoir preservation conditions are the key factor for oil enrichment in the strike-slip fault zone of northern Tarim, and the Aman transition zone in the depression is richer in oil and gas and has greater potential for exploration and development.展开更多
To reveal the law of oiliness of the Upper Cretaceous carbonate reservoirs in the Middle East and factors controlling the oiliness, the Mishrif Formation of the H oilfield in Iraq was examined comprehensively. Based o...To reveal the law of oiliness of the Upper Cretaceous carbonate reservoirs in the Middle East and factors controlling the oiliness, the Mishrif Formation of the H oilfield in Iraq was examined comprehensively. Based on core observation and description, casting thin section analysis, and statistics of physical property and pore-throat structure parameter, etc., in combination with previous achievements and understanding, it is pointed out that the coring interval of Mishrif Formation has strong oiliness heterogeneity, and can be divided into 4 grades, oil rich, oil immersed, oil spot, and oil trace; the oil-bearing grade has obvious facies-controlled characteristic in macroscopic view; and in different oil-bearing grades, relatively oil-rich sections present higher karst development intensity, better physical properties and pore-throat structure characteristics. It is concluded through the study that the sedimentary microenvironment and eogenetic karstification determine the macroscopic oiliness of the reservoir in Mishrif Formation of H Oilfield, and the improvement of pore-throat structure caused by eogenetic karstification is the decisive factor of the micro oil-bearing difference of the reservoir. Finally,the genetic model of reservoir development and oil-bearing difference was established.展开更多
Through fault structure analysis and chronology study, we discuss the origin and growth mechanisms of strike-slip faults in the Tarim Basin.(1) Multiple stages strike-slip faults with inherited growth were developed i...Through fault structure analysis and chronology study, we discuss the origin and growth mechanisms of strike-slip faults in the Tarim Basin.(1) Multiple stages strike-slip faults with inherited growth were developed in the central Tarim cratonic basin. The faults initiation time is constrained at the end of Middle Ordovician of about 460 Ma according to U-Pb dating of the fault cements and seismic interpretation.(2) The formation of the strike-slip faults was controlled by the near N-S direction stress field caused by far-field compression of the closing of the Proto-Tethys Ocean.(3) The faults localization and characteristics were influenced by the pre-existing structures of the NE trending weakening zones in the basement and lithofacies change from south to north.(4) Following the fault initiation under the Andersonian mechanism, the strike-slip fault growth was dominantly fault linkage, associated with fault tip propagation and interaction of non-Andersonian mechanisms.(5) Sequential slip accommodated deformation in the conjugate strike-slip fault interaction zones, strong localization of the main displacement and deformation occurred in the overlap zones in the northern Tarim, while the fault tips, particularly of narrow-deep grabens, and strike-slip segments in thrust zones accumulated more deformation and strain in the Central uplift. In conclusion, non-Andersonian mechanisms, dominantly fault linkage and interaction, resulted in the small displacement but long intraplate strike-slip fault development in the central Tarim Basin. The regional and localized field stress, and pre-existing structures and lithofacies difference had strong impacts on the diversity of the strike-slip faults in the Tarim cratonic basin.展开更多
Fault attributes generally display a consistent power–law-scaling relationship.Based on new 3 D seismic data,however,we found some exceptional fault attribute relationships of lengths(L)–throw(T)(vertical component ...Fault attributes generally display a consistent power–law-scaling relationship.Based on new 3 D seismic data,however,we found some exceptional fault attribute relationships of lengths(L)–throw(T)(vertical component of displacement),overlap zone length(Lo)–width(Wo)from a strike-slip fault system of the Ordovician carbonates in the Tarim Basin.The L–T relationship shows two linear segments with breakup at^40 km in fault length.This presents an exceptional throw increase in the second stage,which is attributed to a localization of vertical displacement and deformation in overlapping zones other than the different fault scales in a mature fault zone.The Lo–Wo relationship in the overlapping zones shows multiply stepped-shape patterns,suggesting multiple fault differential growth and periodic increase in fault size.Therefore,we propose a new alternative growth model of fault attributes in strike-slip fault zones,in which the overlapping zones accumulated localized displacement and deformation in the intracratonic strike-slip fault zone.展开更多
Early Cambrian shale is an important petroleum source rock around the world.Because of little drilling data and poor seismic data,until recently,organic matter enrichment of the Lower Cambrian Yuertusi and Xishanbulak...Early Cambrian shale is an important petroleum source rock around the world.Because of little drilling data and poor seismic data,until recently,organic matter enrichment of the Lower Cambrian Yuertusi and Xishanbulake formations shale is still an enigma in the Tarim Basin,northwestern China.Total organic carbon(TOC),major and trace element data of Cambrian shale samples from five boreholes have been analyzed to decipher the mechanism of the organic matter enrichment.The results show that the shales deposited in the western restricted intraplatform have much higher TOC contents(3.2%-19.8%,on average 11.0%)than those from the eastern basin(2.2%-10.2%,on average 4.5%).The paleoproductivity proxies(Ba,Ba/Al,P/Al)in the western restricted platform are much higher than those in the eastern basin.The trace element indicators such as V/Cr,Ni/Co,Mo-TOC and Mo_(EF)-U_(EF)suggest an anoxic environment across the basin,but a more restricted environment in the western intraplatform.The paleoproductivity rather than anoxic condition and hydrothermal activity are concluded to have resulted in the differentiation of the organic matter enrichment from the western intraplatform to eastern basin in the early Cambrian shales;the restricted environment was favorable for paleoproductivity and preservation of organic matter.展开更多
Combined with the regional strata filling characteristics of Middle-Upper Cambrian,the present paper conducts a systematic research on sedimentary facies in the basin and its peripheral area by utilizing 164 field out...Combined with the regional strata filling characteristics of Middle-Upper Cambrian,the present paper conducts a systematic research on sedimentary facies in the basin and its peripheral area by utilizing 164 field outcrops and drilling and coring data.Further,the method of“multi-factor comprehensive synthesis based on single-factor analysis”was employed to investigate the sedimentary facies and palaeogeography of the study area and establish the sedimentary facies model.Stratigraphic reveals that the study area represents the pattern of thin-northwest and thicksoutheast by stretching northeast-southwest.Within the present basin,the pattern of“one thin and two thick”predominates,while outside the basin“four thin and three thick”filling feature was found.Sedimentary facies shows that the study area was featured by rimmed carbonate platform.Specifically,carbonate platform,slope and northeastern corner Qinling paleooceanic Basin and southeastern corner Jiangnan Bain was identified from the west to the east.The carbonate platform contains restricted platform,evaporation-restricted platform,semi-restricted platform and the platform margin.Single factor analysis and lithofacies palaeogeographic characteristics manifests that during Middle-Late Cambrian,the western Old land evolved into peneplain stage,and that the eastern and southwestern sub-sags remained connected to the open-sea to some extent.At the time,the shllow seawater circulation was relatively restricted,while the ancient seabed tended to be flat and evaporation characteristics significantly diminished.Secondary sea-level fluctuation intensively influenced the development of scaled grain beach.It is suggested that tide marginal beach,intraplatform shoal subfacies zone,along with Shiqian-SangZhi in southeast and Zhenba-Xinshan in northeast platform-margin beach subfacies zone to be preferable targets for the favorable reservoir facies zone and potential oil and gas reservoir area.展开更多
Fabric of carbonate rock is the important foundation and one of main research contents for study on carbonate sedimentology,and has always been the attention of the academic circles.Botryoidal structures from the Sini...Fabric of carbonate rock is the important foundation and one of main research contents for study on carbonate sedimentology,and has always been the attention of the academic circles.Botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin is a kind of special carbonate fabric,the fabric is named after the shape of a grape.In this paper,from four aspects of the research status,the definition of the botryoidal structures and the related terms,the construction characteristics of the botryoidal structures,the component of the botryoidal structures,geochemical characteristics and the genesis of the botryoidal structures are reviewed.It points out the current research issues of botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin,and put forward that future research should focus on the accurate analysis of its internal construction,precipitation mechanism of the major components,and the construction mechanism of botryoidal structures.展开更多
基金Supported by the National Natural Science Foundation of China (91955204)PetroChina-Southwest Petroleum University Innovation Consortium Science and Technology Cooperation Project (2020CX010101)。
文摘A giant fault-controlled oilfield has been found in the ultra-deep(greater than 6000 m) Ordovician carbonate strata in the northern Tarim Basin. It is of great significance for hydrocarbon accumulation study and oil exploitation to determine the key oil accumulation periods. Based on detailed petrographic analysis, fluid inclusion association(FIA) in calcite samples filling in fractures from 12 wells were analyzed, and key accumulation periods of the strike-slip fault-controlled oilfield was studied by combining oil generation periods of the source rocks, formation periods of the fault and traps, and the fluid inclusion data.(1) There are multiple types of FIA, among them, two types of oil inclusions, the type with yellow fluorescence from the depression area and the type with yellow-green fluorescence from the uplift area with different maturities indicate two oil charging stages.(2) The homogenization temperature of the brine inclusions in FIA is mostly affected by temperature rises, and the minimum temperature of brine inclusions symbiotic with oil inclusions is closer to the reservoir temperature during its forming period.(3) FIA with yellow fluorescence all have homogenization temperatures below 50 ℃, while the FIA with yellow-green fluorescence have homogenization temperatures of 70–90 ℃ tested, suggesting two oil accumulation stages in Middle-Late Caledonian and Late Hercynian.(4) The Middle-Late Ordovician is the key formation period of the strike-slip fault, fracture-cave reservoir and trap there.(5) The oil generation peak of the main source rock of the Lower Cambrian is in the Late Ordovician, and the oil accumulation stage is mainly the Late Ordovician in the depression area, but is mainly the Early Permian in the uplift area. The key oil accumulation period of the strike-slip fault-controlled reservoirs is the Late Caledonian, the depression area has preserved the primary oil reservoirs formed in the Caledonian, while the uplift area has secondary oil reservoirs adjusted from the depression area during the Late Hercynian. Oil reservoir preservation conditions are the key factor for oil enrichment in the strike-slip fault zone of northern Tarim, and the Aman transition zone in the depression is richer in oil and gas and has greater potential for exploration and development.
基金Supported by the China National Science and Technology Major Project(2017ZX05032004-001)
文摘To reveal the law of oiliness of the Upper Cretaceous carbonate reservoirs in the Middle East and factors controlling the oiliness, the Mishrif Formation of the H oilfield in Iraq was examined comprehensively. Based on core observation and description, casting thin section analysis, and statistics of physical property and pore-throat structure parameter, etc., in combination with previous achievements and understanding, it is pointed out that the coring interval of Mishrif Formation has strong oiliness heterogeneity, and can be divided into 4 grades, oil rich, oil immersed, oil spot, and oil trace; the oil-bearing grade has obvious facies-controlled characteristic in macroscopic view; and in different oil-bearing grades, relatively oil-rich sections present higher karst development intensity, better physical properties and pore-throat structure characteristics. It is concluded through the study that the sedimentary microenvironment and eogenetic karstification determine the macroscopic oiliness of the reservoir in Mishrif Formation of H Oilfield, and the improvement of pore-throat structure caused by eogenetic karstification is the decisive factor of the micro oil-bearing difference of the reservoir. Finally,the genetic model of reservoir development and oil-bearing difference was established.
基金Supported by the National Natural Science Foundation of China(91955204)PetroChina-Southwest Petroleum University Innovation Consortium Science and Technology Cooperation Project(2020CX010101)。
文摘Through fault structure analysis and chronology study, we discuss the origin and growth mechanisms of strike-slip faults in the Tarim Basin.(1) Multiple stages strike-slip faults with inherited growth were developed in the central Tarim cratonic basin. The faults initiation time is constrained at the end of Middle Ordovician of about 460 Ma according to U-Pb dating of the fault cements and seismic interpretation.(2) The formation of the strike-slip faults was controlled by the near N-S direction stress field caused by far-field compression of the closing of the Proto-Tethys Ocean.(3) The faults localization and characteristics were influenced by the pre-existing structures of the NE trending weakening zones in the basement and lithofacies change from south to north.(4) Following the fault initiation under the Andersonian mechanism, the strike-slip fault growth was dominantly fault linkage, associated with fault tip propagation and interaction of non-Andersonian mechanisms.(5) Sequential slip accommodated deformation in the conjugate strike-slip fault interaction zones, strong localization of the main displacement and deformation occurred in the overlap zones in the northern Tarim, while the fault tips, particularly of narrow-deep grabens, and strike-slip segments in thrust zones accumulated more deformation and strain in the Central uplift. In conclusion, non-Andersonian mechanisms, dominantly fault linkage and interaction, resulted in the small displacement but long intraplate strike-slip fault development in the central Tarim Basin. The regional and localized field stress, and pre-existing structures and lithofacies difference had strong impacts on the diversity of the strike-slip faults in the Tarim cratonic basin.
基金partly supported by the National Natural Science Foundation of China(Grant No.91955204)Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(Grant No.2020CX010300)。
文摘Fault attributes generally display a consistent power–law-scaling relationship.Based on new 3 D seismic data,however,we found some exceptional fault attribute relationships of lengths(L)–throw(T)(vertical component of displacement),overlap zone length(Lo)–width(Wo)from a strike-slip fault system of the Ordovician carbonates in the Tarim Basin.The L–T relationship shows two linear segments with breakup at^40 km in fault length.This presents an exceptional throw increase in the second stage,which is attributed to a localization of vertical displacement and deformation in overlapping zones other than the different fault scales in a mature fault zone.The Lo–Wo relationship in the overlapping zones shows multiply stepped-shape patterns,suggesting multiple fault differential growth and periodic increase in fault size.Therefore,we propose a new alternative growth model of fault attributes in strike-slip fault zones,in which the overlapping zones accumulated localized displacement and deformation in the intracratonic strike-slip fault zone.
基金partly supported by the National Natural Science Foundation of China(Grant No.42241206,91955204)the Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(Grant No.4224100017,2020CX010101)。
文摘Early Cambrian shale is an important petroleum source rock around the world.Because of little drilling data and poor seismic data,until recently,organic matter enrichment of the Lower Cambrian Yuertusi and Xishanbulake formations shale is still an enigma in the Tarim Basin,northwestern China.Total organic carbon(TOC),major and trace element data of Cambrian shale samples from five boreholes have been analyzed to decipher the mechanism of the organic matter enrichment.The results show that the shales deposited in the western restricted intraplatform have much higher TOC contents(3.2%-19.8%,on average 11.0%)than those from the eastern basin(2.2%-10.2%,on average 4.5%).The paleoproductivity proxies(Ba,Ba/Al,P/Al)in the western restricted platform are much higher than those in the eastern basin.The trace element indicators such as V/Cr,Ni/Co,Mo-TOC and Mo_(EF)-U_(EF)suggest an anoxic environment across the basin,but a more restricted environment in the western intraplatform.The paleoproductivity rather than anoxic condition and hydrothermal activity are concluded to have resulted in the differentiation of the organic matter enrichment from the western intraplatform to eastern basin in the early Cambrian shales;the restricted environment was favorable for paleoproductivity and preservation of organic matter.
基金This research is from the projects for National Natural Science Foundation of China(41402126)major special projects for national science-technology of“twelfth five-year plan”(2011ZX05004-005-03)+1 种基金projects of CNPC science and innovation fund(2011D-5006-0105)joint funding results for scientific research innovation team construction plan of Sichuan provincial universities and colleges“natural gas geology”.
文摘Combined with the regional strata filling characteristics of Middle-Upper Cambrian,the present paper conducts a systematic research on sedimentary facies in the basin and its peripheral area by utilizing 164 field outcrops and drilling and coring data.Further,the method of“multi-factor comprehensive synthesis based on single-factor analysis”was employed to investigate the sedimentary facies and palaeogeography of the study area and establish the sedimentary facies model.Stratigraphic reveals that the study area represents the pattern of thin-northwest and thicksoutheast by stretching northeast-southwest.Within the present basin,the pattern of“one thin and two thick”predominates,while outside the basin“four thin and three thick”filling feature was found.Sedimentary facies shows that the study area was featured by rimmed carbonate platform.Specifically,carbonate platform,slope and northeastern corner Qinling paleooceanic Basin and southeastern corner Jiangnan Bain was identified from the west to the east.The carbonate platform contains restricted platform,evaporation-restricted platform,semi-restricted platform and the platform margin.Single factor analysis and lithofacies palaeogeographic characteristics manifests that during Middle-Late Cambrian,the western Old land evolved into peneplain stage,and that the eastern and southwestern sub-sags remained connected to the open-sea to some extent.At the time,the shllow seawater circulation was relatively restricted,while the ancient seabed tended to be flat and evaporation characteristics significantly diminished.Secondary sea-level fluctuation intensively influenced the development of scaled grain beach.It is suggested that tide marginal beach,intraplatform shoal subfacies zone,along with Shiqian-SangZhi in southeast and Zhenba-Xinshan in northeast platform-margin beach subfacies zone to be preferable targets for the favorable reservoir facies zone and potential oil and gas reservoir area.
基金This study was supported by the National Natural Science Foundation of China(Grant No.41402126)the National Science and Technology Major Project(Grant No.2016ZX05004002-001).
文摘Fabric of carbonate rock is the important foundation and one of main research contents for study on carbonate sedimentology,and has always been the attention of the academic circles.Botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin is a kind of special carbonate fabric,the fabric is named after the shape of a grape.In this paper,from four aspects of the research status,the definition of the botryoidal structures and the related terms,the construction characteristics of the botryoidal structures,the component of the botryoidal structures,geochemical characteristics and the genesis of the botryoidal structures are reviewed.It points out the current research issues of botryoidal structures from the Sinian Dengying Formation in the Sichuan Basin,and put forward that future research should focus on the accurate analysis of its internal construction,precipitation mechanism of the major components,and the construction mechanism of botryoidal structures.
