Study on the difference of petroleum accumulation between Paleogene and Neogene in the western Bozhong Sag,Bohai Bay Basin
Through the simulation of hydrocarbon generation and expulsion history of source rocks,oil-source correlation,petroleum filling history,and fault analysis of the western Bozhong Sag,Bohai Bay Basin,combined with the structural evolution history and controlling fault activity history,the petroleum origins,accumulation time,and the fault migration pathway system in the Paleogene and Neogene reservoirs in western Bozhong Sag were analyzed.The results shows that:(1)The Paleogene petroleum in the western Bozhong Sag is mainly concentrated in the reservoirs of the Oligocene Dongying Formation Mbrs 2 and 3(E3d2 and E3d3)of the northern steep slope zone,while the Neogene petroleum in the western Bozhong Sag is distributed in the shallow Guantao Formation and Minghuazhen Formation reservoirs of the northern steep slope zone,western gentle slope zone,and central structural zone.The petroleum reserves of the Neogene in the central structural zone and western gentle slope zone are signifi-cantly higher than those in the northern steep slope zone.(2)The significant source rocks of the western Bozhong Sag are the Shahejie Formation Mbrs 1 and 3(E2s,and E2s3),while the source rocks of the E3d3 also contribute to the petroleum reservoirs in the northern steep slope zone.The accumulation of petroleum in the western Bozhong Sag can be divided into three stages.The discovered petroleum reservoirs mainly formed in two stages.The discovered petroleum reservoirs are mainly formed in the second stage(10-5 Ma)and the third stage(since 5 Ma).The petro-leum generated by the source rock of Shahejie Formation in the first large amount of hydrocarbon generation and expulsion period,between 30 and 20 Ma ago,remains undiscovered.The fault crossing layer and formation time of the fault have a significant controlling effect on the differential enrichment of petroleum in the deep and shallow layers.(3)The shallow Neogene oil and gas reservoirs in the research area are mainly controlled by the communi-cation of shallow,medium,and deep through-source faults formed by neotectonic movements.Mature oil and gas generated by the Shahejie Formation source rocks are transported through multiple long-term active faults and other transport systems;The oil reservoirs of the Paleogene Dongying Formation are mainly controlled by a fault system that only extends to the Dongying Formation,and their oil and gas mainly come from the underlying source rocks of the Shahejie Formation and the third member of the Dongying Formation;The deep Shahejie Formation may develop self generating and self storing oil and gas reservoirs,but no exploration discoveries have been made yet.
through-source faultsbasin simulationaccumulation periodfluid inclusionsoil-source correla-tionbiomarkerssource rock of Shahejie FormationNeogenePaleogenewestern Bozhong Sag
万方数据
维普
