The Linnan subsag is a petroliferous, secondary tectonic unit of the Huimin sag that is located in the western part of the Jiyang depression in the Bohai Bay basin, eastern China. In this study, the authors calculated...The Linnan subsag is a petroliferous, secondary tectonic unit of the Huimin sag that is located in the western part of the Jiyang depression in the Bohai Bay basin, eastern China. In this study, the authors calculated basin extensional rate and slipping displacement of boundary faults in the dip and strike directions, using seismic and drilling data. The evolution of the Linnan transtensional basin from the Eogene through the Quaternary is quantitatively described, and a dynamic model is established. The Linshan and Xiakou boundary faults of the Linnan subsag are used as a case study to describe a method to calculate the strike and dip slipping displacements of active faults under oblique extension. The results quantitatively illustrate the behavior of the Linnan subsag boundary faults over time. The Linnan subsag transtensional basin experienced four stages of evolution: weak extension during the Kongdian Formation, rapid extension and fault depression during the fourth member of the Shahejie Formation,intensive transtension and fault depression during the third member of the Shahejie Formation-Dongying Formation, and weakening fault depression during the Guantao Formation-Pingyuan Formation.The results of this study provide further understanding of the processes of petroleum migration and accumulation in the region.展开更多
Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and ...Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and minerals were characterized microscopically,the measured trap sealing indexes were compared,the biomarker compounds of crude oil were extracted,the genesis of condensate gas was identified,and the reservoir-forming conditions were examined.On this basis,the Paleogene Enping Formation in the Huizhou 26 subsag was systematically analyzed for the potential of oil and gas resources,the development characteristics of large-scale high-quality conglomerate reservoirs,the trapping effectiveness of faults,the hydrocarbon migration and accumulation model,and the formation conditions and exploration targets of large-and medium-sized glutenite-rich oil and gas fields.The research results were obtained in four aspects.First,the Paleogene Wenchang Formation in the Huizhou 26 subsag develops extensive and thick high-quality source rocks of semi-deep to deep lacustrine subfacies,which have typical hydrocarbon expulsion characteristics of"great oil generation in the early stage and huge gas expulsion in the late stage",providing a sufficient material basis for hydrocarbon accumulation in the Enping Formation.Second,under the joint control of the steep slope zone and transition zone of the fault within the sag,the large-scale near-source glutenite reservoirs are highly heterogeneous,with the development scale dominated hierarchically by three factors(favorable facies zone,particle component,and microfracture).The(subaqueous)distributary channels near the fault system,with equal grains,a low mud content(<5%),and a high content of feldspar composition,are conducive to the development of sweet spot reservoirs.Third,the strike-slip pressurization trap covered by stable lake flooding mudstone is a necessary condition for oil and gas preservation,and the NE and nearly EW faults obliquely to the principal stress have the best control on traps.Fourth,the spatiotemporal configuration of high-quality source rocks,fault transport/sealing,and glutenite reservoirs controls the degree of hydrocarbon enrichment.From top to bottom,three hydrocarbon accumulation units,i.e.low-fill zone,transition zone,and high-fill zone,are recognized.The main area of the channel in the nearly pressurized source-connecting fault zone is favorable for large-scale hydrocarbon enrichment.The research results suggest a new direction for the exploration of large-scale glutenite-rich reservoirs in the Enping Formation of the Pearl River Mouth Basin,and present a major breakthrough in oil and gas exploration.展开更多
A transfer zone in rift basins preserves important information on regional tectonic evolution and plays significant roles in hydrocarbon accumulation.Based on the systematic analysis of 3D seismic data and hydrocarbon...A transfer zone in rift basins preserves important information on regional tectonic evolution and plays significant roles in hydrocarbon accumulation.Based on the systematic analysis of 3D seismic data and hydrocarbon accumulation conditions,the geometry,kinematics,and reservoir control of a large synthetic overlapping transfer zone in the south of the Wenchang A subsag in the Zhujiang(Pearl)River Mouth basin were investigated.Results indicate that the development and evolution of the transfer zone was controlled by the interaction between pre-existing faults and regional stress transformation.The intense rifting of the main faults of the transfer zone controlled the development of source rocks and faultcontrolled slope break paleogeomorphology.The strike-slip overprint since the Oligocene is conducive to the formation of a large-scale fault-anticline trap,and the secondary faults in the transfer zone contribute to the hydrocarbon transportation.The conjugate intersection area of the NE-and NW-trending faults offers more opportunity for hydrocarbon migration and accumulation.展开更多
Minfeng sub-sag in the Bohai Bay Basin was taken as an example.The Wells Yanxie 233,Yongxie 932 and Yan 22 were selected for on-site carbon isotope detection.Then,based on sufficient carbon isotope datawhich were acqu...Minfeng sub-sag in the Bohai Bay Basin was taken as an example.The Wells Yanxie 233,Yongxie 932 and Yan 22 were selected for on-site carbon isotope detection.Then,based on sufficient carbon isotope datawhich were acquired on the drilling site using the brand-new carbon isotopic measuring instrument,the carbon i sotope dataand composition data of natural gas produced in this areawerecompared.Andcombined with the evolution of source rocks,the geochemical characteristics of crude oil,the depositional environment of reservoirs and the physical properties,single-well charging characteristics and regional charging area ofnatural gas wereanalyzed.Finally,the feasibility of on-sitecarbon isotope detection method to discriminate hydrocarbon charging was discussed.And the following research results were obtained.First,deep hy drocarbon charging happened in thePurely Purely Lower Sha 4 Member in Well Yanxie 233,and its natural gas is the mixture of the oil cracking gas of deep layers and the thernal cracking gas of autochthonous source rocks.Second,the natural gas in the third and fourth Members ofShahejieFormation in Well Yongxie 932 is the thermale racking gas of autochthonous source rocks,but deep gas charging occurred in particularhole sections.Third,the carbon isotope of associated gas in Well block Yan 22 is high in the central area and low in both sides and high in the south and low in the north,which is accordant with the distributi on characteristics ofreservoir physicalproperties,indicating thatthe charging ofhigh-maturity natural gas is under the control of reservoir physical properties.Fourth,the oil in Well block Yan 22 is the product of autochthonous source rocks in the mature stage while the natural gas is the autochthonous oil-associated gas combined with the charging of deep high-maturity product.It is concluded that there is a high-maturity hydrocarbon charging area in the northwest of the northern slope of the Minfeng sub-sag,and it is a favorable hydrocarbon exploration target.What's more,the on-site carbon isotope rapid detection technology can provide a large number of continuous three-dimensional carbon isotope data,and it can be used to quickly analyze the characteristics of Studying hydrocarbon charging isquite important for searchingexploration targets and confirming well locations.In thispaper,the north slope of the hydrocarbon charging and determine the source and ori gin of hydrocarbon,so as to provide reference for hydrocarbon development deployment.展开更多
There are abundant hydrocarbon resources in the western subsag of Bozhong sag in the Bohai Bay Basin,where oilegas discoveries have been made in those shallow Neogene and Paleogene reservoirs and deep Mesozoic buried ...There are abundant hydrocarbon resources in the western subsag of Bozhong sag in the Bohai Bay Basin,where oilegas discoveries have been made in those shallow Neogene and Paleogene reservoirs and deep Mesozoic buried hill reservoirs,but no better understandings have yet been achieved in terms of the process of hydrocarbon accumulation and the relationship between deep buried hill reservoirs and the allocation of shallow reservoirs.Based on the organic geochemical analysis of source rocks and basin modeling of hydrocarbon generation evolution,distribution characteristics of fluid inclusion and homogeneous temperature measurement,combined with the characteristics of oil-source biomarkers,the process of hydrocarbon accumulation in this study area was resumed based upon the regional tectonic background.The following findings were obtained.(1)There are 3 sets of source rocks in the third and first members of Paleogene Shahejie Fm,and the second lower member of Paleogene Dongying Fm;the reservoirs in the peripheral uplift zones include Mesozoic volcanic rocks,Archean metamorphic rocks,and PaleogeneeNeogene deltaefluvial porous sandstones.Hydrocarbon generated in this sag migrated along the fault and the unconformity surface to the slope before accumulated in the peripheral tectonic zones,resulting in 3 sets of sourceereservoirecaprock assemblages formed with the characteristics of reservoir formation in compound oil and gas accumulation zones.(2)The stratum in the third member of Shahejie Fm is the main source rock.(3)The above three assemblages went through four periods of generating process during the geological time of 11e1 Ma.Vertically hydrocarbon sources first filled in the deep Mesozoic and Archean reservoirs,then migrated and accumulated in the shallow Neogene and Paleogene reservoirs,where multiple shore-term rapid filling of high-temperature fluids led to this typical oil and gas pooling mode.展开更多
Abundant aromatic fractions were detected in oils from the Linnan subsag, including aphthalenes, phenanthrenes, triaromatic steroids, biphenyl, fluorenes, dibenzothiophenes, dibenzofuranes, as well as some typical hig...Abundant aromatic fractions were detected in oils from the Linnan subsag, including aphthalenes, phenanthrenes, triaromatic steroids, biphenyl, fluorenes, dibenzothiophenes, dibenzofuranes, as well as some typical higher plant-sourced compounds, such as pyrene, benzopyrene, fluoranthene, chryaene, benzofluoranthrene, perylene and cadalene. Occurrences of biomarkers indicate that oils from the Linnan subsag are typical terrestrially genetic oils. Developed in the depositional environment is a strong reduction condition typical of brackish-saline lake. Thermal evolution has entered into the mature-high mature stage.展开更多
Based on the comprehensive analysis of data from petrology and mineralogy,well logging,seismic surveys,paleontology,and geochemistry,a detailed research was conducted on paleoenvironmental and paleoclimatic conditions...Based on the comprehensive analysis of data from petrology and mineralogy,well logging,seismic surveys,paleontology,and geochemistry,a detailed research was conducted on paleoenvironmental and paleoclimatic conditions,and modeling of the source rocks in the second member of the Eocene Wenchang Formation(Wen 2 Member)in the Northern Shunde Subsag at the southwestern margin of the Pearl River Mouth Basin.The Wen 2 Member hosts excellent,thick lacustrine source rocks with strong longitudinal heterogeneity and an average total organic carbon(TOC)content of over 4.9%.The Wen 2 Member can be divided into three units(I,II,III)from bottom to top.Unit I features excellent source rocks with Type I organic matters(average TOC of 5.9%)primarily sourced from lake organisms;Unit II hosts source rocks dominated by Type II2 organic matters(average TOC of 2.2%),which are originated from mixed sources dominated by terrestrial input.Unit III contains good to excellent source rocks dominated by Type II1 organic matters(average TOC of 4.9%),which are mainly contributed by lake organisms and partially by terrestrial input.Under the background of rapid subsidence and limited source supply during intense rifting period in the Eocene,excellent source rocks were developed in Wen 2 Member in the Northern Shunde Subsag under the coordinated control of warm and humid climate,volcanic activity,and deep-water reducing conditions.During the deposition of Unit I,the warm and humid climate and volcanic activity promoted the proliferation of lake algaes,primarily Granodiscus,resulting in high initial productivity,and deep-water reducing conditions enabled satisfactory preservation of organic matters.These factors jointly controlled the development and occurrence of excellent source rocks.During the deposition of Unit II,a transition from warm to cool and semi-arid paleoclimatic conditions led to a decrease in lake algaes and initial productivity.Additionally,enhanced terrestrial input and shallow-water,weakly oxidizing water conditions caused a significant dilution and decomposition of organic matters,degrading the quality of source rocks.During the deposition of Unit III,when the paleoclimatic conditions are cool and humid,Pediastrum and Botryococcus began to thrive,leading to an increase in productivity.Meanwhile,the reducing environment of semi-deep water facilitated the preservation of excellent source rocks,albeit slightly inferior to those in Unit I.The study results clarify the differential origins and development models of various source rocks in the Shunde Sag,offering valuable guidance for evaluating source rocks and selecting petroleum exploration targets in similar marginal sags.展开更多
基金financially supported by the National Science and Technology Major Project of China(No. 2016ZX05006)
文摘The Linnan subsag is a petroliferous, secondary tectonic unit of the Huimin sag that is located in the western part of the Jiyang depression in the Bohai Bay basin, eastern China. In this study, the authors calculated basin extensional rate and slipping displacement of boundary faults in the dip and strike directions, using seismic and drilling data. The evolution of the Linnan transtensional basin from the Eogene through the Quaternary is quantitatively described, and a dynamic model is established. The Linshan and Xiakou boundary faults of the Linnan subsag are used as a case study to describe a method to calculate the strike and dip slipping displacements of active faults under oblique extension. The results quantitatively illustrate the behavior of the Linnan subsag boundary faults over time. The Linnan subsag transtensional basin experienced four stages of evolution: weak extension during the Kongdian Formation, rapid extension and fault depression during the fourth member of the Shahejie Formation,intensive transtension and fault depression during the third member of the Shahejie Formation-Dongying Formation, and weakening fault depression during the Guantao Formation-Pingyuan Formation.The results of this study provide further understanding of the processes of petroleum migration and accumulation in the region.
基金Supported by the CNOOC Major Technology Project During the 14th FIVE-YEAR PLAN PERIOD(KJGG2022-0403)CNOOC Major Technology Project(KJZH-2021-0003-00).
文摘Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and minerals were characterized microscopically,the measured trap sealing indexes were compared,the biomarker compounds of crude oil were extracted,the genesis of condensate gas was identified,and the reservoir-forming conditions were examined.On this basis,the Paleogene Enping Formation in the Huizhou 26 subsag was systematically analyzed for the potential of oil and gas resources,the development characteristics of large-scale high-quality conglomerate reservoirs,the trapping effectiveness of faults,the hydrocarbon migration and accumulation model,and the formation conditions and exploration targets of large-and medium-sized glutenite-rich oil and gas fields.The research results were obtained in four aspects.First,the Paleogene Wenchang Formation in the Huizhou 26 subsag develops extensive and thick high-quality source rocks of semi-deep to deep lacustrine subfacies,which have typical hydrocarbon expulsion characteristics of"great oil generation in the early stage and huge gas expulsion in the late stage",providing a sufficient material basis for hydrocarbon accumulation in the Enping Formation.Second,under the joint control of the steep slope zone and transition zone of the fault within the sag,the large-scale near-source glutenite reservoirs are highly heterogeneous,with the development scale dominated hierarchically by three factors(favorable facies zone,particle component,and microfracture).The(subaqueous)distributary channels near the fault system,with equal grains,a low mud content(<5%),and a high content of feldspar composition,are conducive to the development of sweet spot reservoirs.Third,the strike-slip pressurization trap covered by stable lake flooding mudstone is a necessary condition for oil and gas preservation,and the NE and nearly EW faults obliquely to the principal stress have the best control on traps.Fourth,the spatiotemporal configuration of high-quality source rocks,fault transport/sealing,and glutenite reservoirs controls the degree of hydrocarbon enrichment.From top to bottom,three hydrocarbon accumulation units,i.e.low-fill zone,transition zone,and high-fill zone,are recognized.The main area of the channel in the nearly pressurized source-connecting fault zone is favorable for large-scale hydrocarbon enrichment.The research results suggest a new direction for the exploration of large-scale glutenite-rich reservoirs in the Enping Formation of the Pearl River Mouth Basin,and present a major breakthrough in oil and gas exploration.
基金Supported by the National Natural Science Foundation of China(Nos.42302155,42072169,42072235)the Natural Science Foundation of Shandong Province(No.ZR2023QD016)+2 种基金the China Postdoctoral Science Foundation(No.2022M713461)the Qingdao Postdoctoral Application Research Funds(No.QDBSH20220202067)the Fundamental Research Funds for the Central Universities(No.22CX06005A)。
文摘A transfer zone in rift basins preserves important information on regional tectonic evolution and plays significant roles in hydrocarbon accumulation.Based on the systematic analysis of 3D seismic data and hydrocarbon accumulation conditions,the geometry,kinematics,and reservoir control of a large synthetic overlapping transfer zone in the south of the Wenchang A subsag in the Zhujiang(Pearl)River Mouth basin were investigated.Results indicate that the development and evolution of the transfer zone was controlled by the interaction between pre-existing faults and regional stress transformation.The intense rifting of the main faults of the transfer zone controlled the development of source rocks and faultcontrolled slope break paleogeomorphology.The strike-slip overprint since the Oligocene is conducive to the formation of a large-scale fault-anticline trap,and the secondary faults in the transfer zone contribute to the hydrocarbon transportation.The conjugate intersection area of the NE-and NW-trending faults offers more opportunity for hydrocarbon migration and accumulation.
基金Project supported by the National Major Science and Technology Project"Key Technologies for Seismic and Wellbore Fine Exploration"(No.2016ZX05006-002)the RIPED Scientific Reseach and Technology Development Project"Real-time Carbon Isotope Detection and Gas-bearing Model"(No.2018ycq01).
文摘Minfeng sub-sag in the Bohai Bay Basin was taken as an example.The Wells Yanxie 233,Yongxie 932 and Yan 22 were selected for on-site carbon isotope detection.Then,based on sufficient carbon isotope datawhich were acquired on the drilling site using the brand-new carbon isotopic measuring instrument,the carbon i sotope dataand composition data of natural gas produced in this areawerecompared.Andcombined with the evolution of source rocks,the geochemical characteristics of crude oil,the depositional environment of reservoirs and the physical properties,single-well charging characteristics and regional charging area ofnatural gas wereanalyzed.Finally,the feasibility of on-sitecarbon isotope detection method to discriminate hydrocarbon charging was discussed.And the following research results were obtained.First,deep hy drocarbon charging happened in thePurely Purely Lower Sha 4 Member in Well Yanxie 233,and its natural gas is the mixture of the oil cracking gas of deep layers and the thernal cracking gas of autochthonous source rocks.Second,the natural gas in the third and fourth Members ofShahejieFormation in Well Yongxie 932 is the thermale racking gas of autochthonous source rocks,but deep gas charging occurred in particularhole sections.Third,the carbon isotope of associated gas in Well block Yan 22 is high in the central area and low in both sides and high in the south and low in the north,which is accordant with the distributi on characteristics ofreservoir physicalproperties,indicating thatthe charging ofhigh-maturity natural gas is under the control of reservoir physical properties.Fourth,the oil in Well block Yan 22 is the product of autochthonous source rocks in the mature stage while the natural gas is the autochthonous oil-associated gas combined with the charging of deep high-maturity product.It is concluded that there is a high-maturity hydrocarbon charging area in the northwest of the northern slope of the Minfeng sub-sag,and it is a favorable hydrocarbon exploration target.What's more,the on-site carbon isotope rapid detection technology can provide a large number of continuous three-dimensional carbon isotope data,and it can be used to quickly analyze the characteristics of Studying hydrocarbon charging isquite important for searchingexploration targets and confirming well locations.In thispaper,the north slope of the hydrocarbon charging and determine the source and ori gin of hydrocarbon,so as to provide reference for hydrocarbon development deployment.
基金supported by the National Major Science and Technology Project“Comprehensive study on hydrocarbon accumulation and favorable exploration targets in buried-hill reservoirs in the Bohai Bay Basin”(No.:2016ZX05024-003-010)CNOOC Research Project“Petroleum geology,typical hydrocarbon accumulation mechanisms and exploration prospects in buried-hill reservoirs in the Bohai Sea area”(No.:CCL2014TJXZSS0870).
文摘There are abundant hydrocarbon resources in the western subsag of Bozhong sag in the Bohai Bay Basin,where oilegas discoveries have been made in those shallow Neogene and Paleogene reservoirs and deep Mesozoic buried hill reservoirs,but no better understandings have yet been achieved in terms of the process of hydrocarbon accumulation and the relationship between deep buried hill reservoirs and the allocation of shallow reservoirs.Based on the organic geochemical analysis of source rocks and basin modeling of hydrocarbon generation evolution,distribution characteristics of fluid inclusion and homogeneous temperature measurement,combined with the characteristics of oil-source biomarkers,the process of hydrocarbon accumulation in this study area was resumed based upon the regional tectonic background.The following findings were obtained.(1)There are 3 sets of source rocks in the third and first members of Paleogene Shahejie Fm,and the second lower member of Paleogene Dongying Fm;the reservoirs in the peripheral uplift zones include Mesozoic volcanic rocks,Archean metamorphic rocks,and PaleogeneeNeogene deltaefluvial porous sandstones.Hydrocarbon generated in this sag migrated along the fault and the unconformity surface to the slope before accumulated in the peripheral tectonic zones,resulting in 3 sets of sourceereservoirecaprock assemblages formed with the characteristics of reservoir formation in compound oil and gas accumulation zones.(2)The stratum in the third member of Shahejie Fm is the main source rock.(3)The above three assemblages went through four periods of generating process during the geological time of 11e1 Ma.Vertically hydrocarbon sources first filled in the deep Mesozoic and Archean reservoirs,then migrated and accumulated in the shallow Neogene and Paleogene reservoirs,where multiple shore-term rapid filling of high-temperature fluids led to this typical oil and gas pooling mode.
基金supported by the University Research Program of Shandong Province (Grant No.J09LE08)the Open Found of Key Laboratory of Depositional Mineralization & Sedimentary Mineral, Shandong Province (Grant No.DMSM200807)
文摘Abundant aromatic fractions were detected in oils from the Linnan subsag, including aphthalenes, phenanthrenes, triaromatic steroids, biphenyl, fluorenes, dibenzothiophenes, dibenzofuranes, as well as some typical higher plant-sourced compounds, such as pyrene, benzopyrene, fluoranthene, chryaene, benzofluoranthrene, perylene and cadalene. Occurrences of biomarkers indicate that oils from the Linnan subsag are typical terrestrially genetic oils. Developed in the depositional environment is a strong reduction condition typical of brackish-saline lake. Thermal evolution has entered into the mature-high mature stage.
基金Supported by the Research Project of China National Offshore Oil Corporation(SCKY-2023-HN-3)。
文摘Based on the comprehensive analysis of data from petrology and mineralogy,well logging,seismic surveys,paleontology,and geochemistry,a detailed research was conducted on paleoenvironmental and paleoclimatic conditions,and modeling of the source rocks in the second member of the Eocene Wenchang Formation(Wen 2 Member)in the Northern Shunde Subsag at the southwestern margin of the Pearl River Mouth Basin.The Wen 2 Member hosts excellent,thick lacustrine source rocks with strong longitudinal heterogeneity and an average total organic carbon(TOC)content of over 4.9%.The Wen 2 Member can be divided into three units(I,II,III)from bottom to top.Unit I features excellent source rocks with Type I organic matters(average TOC of 5.9%)primarily sourced from lake organisms;Unit II hosts source rocks dominated by Type II2 organic matters(average TOC of 2.2%),which are originated from mixed sources dominated by terrestrial input.Unit III contains good to excellent source rocks dominated by Type II1 organic matters(average TOC of 4.9%),which are mainly contributed by lake organisms and partially by terrestrial input.Under the background of rapid subsidence and limited source supply during intense rifting period in the Eocene,excellent source rocks were developed in Wen 2 Member in the Northern Shunde Subsag under the coordinated control of warm and humid climate,volcanic activity,and deep-water reducing conditions.During the deposition of Unit I,the warm and humid climate and volcanic activity promoted the proliferation of lake algaes,primarily Granodiscus,resulting in high initial productivity,and deep-water reducing conditions enabled satisfactory preservation of organic matters.These factors jointly controlled the development and occurrence of excellent source rocks.During the deposition of Unit II,a transition from warm to cool and semi-arid paleoclimatic conditions led to a decrease in lake algaes and initial productivity.Additionally,enhanced terrestrial input and shallow-water,weakly oxidizing water conditions caused a significant dilution and decomposition of organic matters,degrading the quality of source rocks.During the deposition of Unit III,when the paleoclimatic conditions are cool and humid,Pediastrum and Botryococcus began to thrive,leading to an increase in productivity.Meanwhile,the reducing environment of semi-deep water facilitated the preservation of excellent source rocks,albeit slightly inferior to those in Unit I.The study results clarify the differential origins and development models of various source rocks in the Shunde Sag,offering valuable guidance for evaluating source rocks and selecting petroleum exploration targets in similar marginal sags.
