The eastern Tarim Basin(Tadong Area)has gained wide attentions on large-scale marine carbonate reservoirs in Cambrian-Ordovician due to significant hydrocarbon discoveries.A systematic analysis combining thin sections...The eastern Tarim Basin(Tadong Area)has gained wide attentions on large-scale marine carbonate reservoirs in Cambrian-Ordovician due to significant hydrocarbon discoveries.A systematic analysis combining thin sections,cores,wireline logs,and seismic data is conducted on Cambrian-Ordovician carbonate platform in the whole eastern Tarim Basin,including Gucheng area,Majiaer area,and western Luobopo rise(Luoxi area).The results show that 8 sub-facies and more than 10 microfacies are developed including open platform,restricted/semi-restricted platform,reef-shoal around platform margin,drowned platform,foreslope,neritic platform,and deep-water basin.As both key areas for hosting petroleum reserves during the Cambrian and Ordovician,the Luoxi area is dominated by deep-water basin facies,while the Gucheng area is dominated by neritic platform facies and deep-water basin facies during the Lower Cambrian.The deposition evolution during the whole Cambrian is dominated by slope facies and deep-water facies,platform margin facies,and platform facies.In contrast,it is dominated by open platform facies during the whole Ordovician.The depositional evolution of carbonate platform is mainly controlled by paleo-geomorphology and sea-level changes.The distribution of paleo-geomorphologic units plays an important role in controlling types and distributions of carbonate platform facies.The transgression assists in growth of reef-shoal complex and lime mud mound in the Early Ordovician.However,with neritic platform and slope being to disappeared,in the Middle Ordovician,platform margin facies are well developed in Gucheng Area.Platform facies and deepwater basin facies are widely distributed.Finally,carbonate platform is drowned due to sea level rising in the Late Ordovician.The depositional evolution of carbonate platform coinciding falling and rising of sea-level changes can be beneficial for appropriate carbonate reservoirs identification and petroleum exploration.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
基金National Natural Science Foundation of China(Grant No.U19B6003-01-01).
文摘The eastern Tarim Basin(Tadong Area)has gained wide attentions on large-scale marine carbonate reservoirs in Cambrian-Ordovician due to significant hydrocarbon discoveries.A systematic analysis combining thin sections,cores,wireline logs,and seismic data is conducted on Cambrian-Ordovician carbonate platform in the whole eastern Tarim Basin,including Gucheng area,Majiaer area,and western Luobopo rise(Luoxi area).The results show that 8 sub-facies and more than 10 microfacies are developed including open platform,restricted/semi-restricted platform,reef-shoal around platform margin,drowned platform,foreslope,neritic platform,and deep-water basin.As both key areas for hosting petroleum reserves during the Cambrian and Ordovician,the Luoxi area is dominated by deep-water basin facies,while the Gucheng area is dominated by neritic platform facies and deep-water basin facies during the Lower Cambrian.The deposition evolution during the whole Cambrian is dominated by slope facies and deep-water facies,platform margin facies,and platform facies.In contrast,it is dominated by open platform facies during the whole Ordovician.The depositional evolution of carbonate platform is mainly controlled by paleo-geomorphology and sea-level changes.The distribution of paleo-geomorphologic units plays an important role in controlling types and distributions of carbonate platform facies.The transgression assists in growth of reef-shoal complex and lime mud mound in the Early Ordovician.However,with neritic platform and slope being to disappeared,in the Middle Ordovician,platform margin facies are well developed in Gucheng Area.Platform facies and deepwater basin facies are widely distributed.Finally,carbonate platform is drowned due to sea level rising in the Late Ordovician.The depositional evolution of carbonate platform coinciding falling and rising of sea-level changes can be beneficial for appropriate carbonate reservoirs identification and petroleum exploration.
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.
