Geochemical studies of crude oil and source rock play an important role in future exploration in Zhanhua Depression.In this study,thirty-one oil samples collected from Shahejie Formation in Zhanhua Depression,Bohai Ba...Geochemical studies of crude oil and source rock play an important role in future exploration in Zhanhua Depression.In this study,thirty-one oil samples collected from Shahejie Formation in Zhanhua Depression,Bohai Bay Basin,NE China have been geochemically analyzed and their organic geochemical characteristics have been applied to differentiate groups of oils.These oil samples can be classified into two families based on multiple biomarker proxies and stable carbon isotopic values.FamilyⅠis characterized by a low ratio of pristane over phytane(Pr/Ph<0.7),a relatively high ratio of phytane over n-C18(Ph/n-C18),varying ratios of gammacerane over C30 hopane(Ga/C30H)and C22/C21 tricyclic terpane,and a low ratio of C19/C23 tricyclic terpane.FamilyⅡis marked by a relatively high Pr/Ph ratio(0.7-1.6),relative low ratios of Ph/n-C18 and C22/C21 tricyclic terpane,and avarying ratio of C19/C23 tricyclic terpane.Both familiesⅠandⅡwithin these crude oils can be subdivided into two families based on different values of stable carbon isotopic composition of individual n-alkanes.Moreover,the potential source rocks of oil samples in FamilyⅠand FamilyⅡwere likely derived from the upper Es4 member and Es3 member,respectively,based on the correlation of organic geochemical characteristics of the oils and source rocks.The results of oil-source rock correlation provide insight into the process from oil generation to migration and to final accumulation,providing a better understanding of factors controlling oil-gas distribution for prediction of sweet spots.展开更多
Two sequences can be identified in the sedimentary strata of the lower Tertiary ShahejieFormation in the Zhanhua hollow. The lowstand, lake-transgressive and highstand systemstracts were formed under the control of an...Two sequences can be identified in the sedimentary strata of the lower Tertiary ShahejieFormation in the Zhanhua hollow. The lowstand, lake-transgressive and highstand systemstracts were formed under the control of ancient structure, palaeotopography, palaeoclimate, sed-iment supply, marine-transgression, and so on. In the paper the authors present a composite se-quence stratigraphical section of the Shahejie Formation in this area, and expound the bounda-ries of parasequences, parasequences set and systems tracts and evolutions of lake sequencestratigraphy and sedimentology and discuss various factors controlling the lake level fluctuation.The differences between lake and marine sequence stratigraphy are also indicated in the paper.The lake sequence stratigraphical study should be based on a synthetic analysis of structural evo-lution, palaeomagnetism, palaeoclimatic changes, geological Well logs, seismic and logging data,palaeontological data, global sea level changes, and so on. The sequence stratigraphical evolutionis closely related to the formation, development and elimination of the whole basin and thesedimentary process.展开更多
Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100...Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100~300-m-thick dark shale,mudstone and limestone encountered in the lower third member of the Eocene Shahejie Formation(Es3l member)in Zhanhua Sag,Bohai Bay Basin,eastern China,routine core analysis,thin sectioning,scanning electron microscopy(SEM),mineralogical and geochemical measurements were used to understand detailed facies characterization and paleoclimate in the member.This Es3l shale sediment includes three sedimentary cycles(C3,C2 and C1),from bottom to top,with complex sedimentary characters and spatial distribution.In terms of the composition,texture,bedding and thickness,six lithofacies are recognized in this succession.Some geochemical parameters,such as trace elements(Sr/Ba,Na/Al,V/Ni,V/(V+Ni),U/Th),carbon and oxygen isotopes(δ^(18)O,δ^(13)C),and total organic carbon content(TOC)indicate that the shales were deposited in a deep to semi-deep lake,with the water column being salty,stratified,enclosed and reductive.During cycles C3 and C2 of the middle-lower sections,the climate was arid,and the water was salty and stratified.Laminated and laminar mudstone-limestone was deposited with moderate organic matter(average TOC 1.8%)and good reservoir quality(average porosity 6.5%),which can be regarded as favorable reservoir.During the C1 cycle,a large amount of organic matter was input from outside the basin and this led to high productivity with a more humid climate.Massive calcareous mudstone was deposited,and this is characterized by high TOC(average 3.6%)and moderate porosity(average 4%),and provides favorable source rocks.展开更多
The residual oil in the fluvial reservoir of Gudong Oilfield is still widely developed even after decades of development.In order to explore the remaining oil in the subsurface fluvial reservoir,we need to have a bett...The residual oil in the fluvial reservoir of Gudong Oilfield is still widely developed even after decades of development.In order to explore the remaining oil in the subsurface fluvial reservoir,we need to have a better understanding on fluvial sandbody characteristics.This paper aims to demonstrate how to quantify anatomy on meandering fluvial architecture.Sedimentologic data from core descriptions of Guantao Formation in Gudong Oilfield were used to identify architectural elements.The upper Guantao Formation consists of ten lithofacies composing five different types of architectural elements.By integrating the available core,well logs,and seismic data,the fluvial sandbody distribution was analyzed.To characterize the fluvial channel geomorphology,we used seismic inversion to explore the stratigraphic correlation and stacking patterns of different channels,and the sandbody isopach map was obtained by the sandbody thickness in each layer.The architectural elements distribution in the plane was mapped by the sandbody isopach map and its profile characteristics.According to the investigation of meandering fluvial outcrops,subsurface meandering fluvial seismic geomorphology,and modern river morphology,the upstream-bar portions are always eroded because of the downstream channel migration.Statistics on the morphometric parameters(bar width/looplength,upstream deflection angle,downstream deflection angle,etc.)of modern meandering river(Ob River)were obtained from the Google Earth.It is found that the bar width/looplength and upstream deflection angle,upstream deflection angle and downstream deflection angle in modern meandering river have a good relationship,and we can have a quantitative architectural characterization on the point bar.This study quantified lithofacies thickness and proportion in different architectural elements of Guantao Formation,which ensures a high resolution anatomy on the small scale architecture.By using this method,the lithofacies proportion in each architectural element was computed,and through the statistics of architectural elements proportion in the Gudong Oilfield,the different lithofacies proportions in the block 6 can be computed.展开更多
基金financially supported by the Chinese NSF Grants[41903064]to Hong Lu。
文摘Geochemical studies of crude oil and source rock play an important role in future exploration in Zhanhua Depression.In this study,thirty-one oil samples collected from Shahejie Formation in Zhanhua Depression,Bohai Bay Basin,NE China have been geochemically analyzed and their organic geochemical characteristics have been applied to differentiate groups of oils.These oil samples can be classified into two families based on multiple biomarker proxies and stable carbon isotopic values.FamilyⅠis characterized by a low ratio of pristane over phytane(Pr/Ph<0.7),a relatively high ratio of phytane over n-C18(Ph/n-C18),varying ratios of gammacerane over C30 hopane(Ga/C30H)and C22/C21 tricyclic terpane,and a low ratio of C19/C23 tricyclic terpane.FamilyⅡis marked by a relatively high Pr/Ph ratio(0.7-1.6),relative low ratios of Ph/n-C18 and C22/C21 tricyclic terpane,and avarying ratio of C19/C23 tricyclic terpane.Both familiesⅠandⅡwithin these crude oils can be subdivided into two families based on different values of stable carbon isotopic composition of individual n-alkanes.Moreover,the potential source rocks of oil samples in FamilyⅠand FamilyⅡwere likely derived from the upper Es4 member and Es3 member,respectively,based on the correlation of organic geochemical characteristics of the oils and source rocks.The results of oil-source rock correlation provide insight into the process from oil generation to migration and to final accumulation,providing a better understanding of factors controlling oil-gas distribution for prediction of sweet spots.
文摘Two sequences can be identified in the sedimentary strata of the lower Tertiary ShahejieFormation in the Zhanhua hollow. The lowstand, lake-transgressive and highstand systemstracts were formed under the control of ancient structure, palaeotopography, palaeoclimate, sed-iment supply, marine-transgression, and so on. In the paper the authors present a composite se-quence stratigraphical section of the Shahejie Formation in this area, and expound the bounda-ries of parasequences, parasequences set and systems tracts and evolutions of lake sequencestratigraphy and sedimentology and discuss various factors controlling the lake level fluctuation.The differences between lake and marine sequence stratigraphy are also indicated in the paper.The lake sequence stratigraphical study should be based on a synthetic analysis of structural evo-lution, palaeomagnetism, palaeoclimatic changes, geological Well logs, seismic and logging data,palaeontological data, global sea level changes, and so on. The sequence stratigraphical evolutionis closely related to the formation, development and elimination of the whole basin and thesedimentary process.
基金This work is granted by the China State Lithologic Key Program(grant no.2017ZX05001-002-002).
文摘Researches into shale lithofacies,their sedimentary environments and relationship benefit understanding both of sedimentary cycle division and unconventional hydrocarbon exploration in lacustrine basins.Based on a 100~300-m-thick dark shale,mudstone and limestone encountered in the lower third member of the Eocene Shahejie Formation(Es3l member)in Zhanhua Sag,Bohai Bay Basin,eastern China,routine core analysis,thin sectioning,scanning electron microscopy(SEM),mineralogical and geochemical measurements were used to understand detailed facies characterization and paleoclimate in the member.This Es3l shale sediment includes three sedimentary cycles(C3,C2 and C1),from bottom to top,with complex sedimentary characters and spatial distribution.In terms of the composition,texture,bedding and thickness,six lithofacies are recognized in this succession.Some geochemical parameters,such as trace elements(Sr/Ba,Na/Al,V/Ni,V/(V+Ni),U/Th),carbon and oxygen isotopes(δ^(18)O,δ^(13)C),and total organic carbon content(TOC)indicate that the shales were deposited in a deep to semi-deep lake,with the water column being salty,stratified,enclosed and reductive.During cycles C3 and C2 of the middle-lower sections,the climate was arid,and the water was salty and stratified.Laminated and laminar mudstone-limestone was deposited with moderate organic matter(average TOC 1.8%)and good reservoir quality(average porosity 6.5%),which can be regarded as favorable reservoir.During the C1 cycle,a large amount of organic matter was input from outside the basin and this led to high productivity with a more humid climate.Massive calcareous mudstone was deposited,and this is characterized by high TOC(average 3.6%)and moderate porosity(average 4%),and provides favorable source rocks.
基金Research Institute of Exploration and Development of Shengli Oilfield for their support in completing the research and their permission to publish the resultsco-funded by the National Key Oil&Gas Project of China (No. 2011ZX05009-002)+2 种基金the National Science and Technology Major Program of China (No2017ZX05009-002)the Youth Project of Education Department of Liaoning Province (No. LJKQZ20222320)the talent scientific research fund of Liaoning Petrochemical University (No. 2021XJJL-028).
文摘The residual oil in the fluvial reservoir of Gudong Oilfield is still widely developed even after decades of development.In order to explore the remaining oil in the subsurface fluvial reservoir,we need to have a better understanding on fluvial sandbody characteristics.This paper aims to demonstrate how to quantify anatomy on meandering fluvial architecture.Sedimentologic data from core descriptions of Guantao Formation in Gudong Oilfield were used to identify architectural elements.The upper Guantao Formation consists of ten lithofacies composing five different types of architectural elements.By integrating the available core,well logs,and seismic data,the fluvial sandbody distribution was analyzed.To characterize the fluvial channel geomorphology,we used seismic inversion to explore the stratigraphic correlation and stacking patterns of different channels,and the sandbody isopach map was obtained by the sandbody thickness in each layer.The architectural elements distribution in the plane was mapped by the sandbody isopach map and its profile characteristics.According to the investigation of meandering fluvial outcrops,subsurface meandering fluvial seismic geomorphology,and modern river morphology,the upstream-bar portions are always eroded because of the downstream channel migration.Statistics on the morphometric parameters(bar width/looplength,upstream deflection angle,downstream deflection angle,etc.)of modern meandering river(Ob River)were obtained from the Google Earth.It is found that the bar width/looplength and upstream deflection angle,upstream deflection angle and downstream deflection angle in modern meandering river have a good relationship,and we can have a quantitative architectural characterization on the point bar.This study quantified lithofacies thickness and proportion in different architectural elements of Guantao Formation,which ensures a high resolution anatomy on the small scale architecture.By using this method,the lithofacies proportion in each architectural element was computed,and through the statistics of architectural elements proportion in the Gudong Oilfield,the different lithofacies proportions in the block 6 can be computed.
