Oil And Gas Accumulation Simulation And Favorable Area Prediction In The Southern Sub-depression Of MXN Sag,Bohai Sea

The MXN depression,the South Sub-vault,is located in the eastern part of the Bohai Bay Basin and is a marginal area with a low level of exploration in the Bohai Sea.The degree of hydrocarbon formation research is low,and the complex and diverse tectonic patterns have an impact on the hydrocarbon reservoir state.Therefore,in this paper,based on the full utilization of previous research results,we adopt the equilibrium profile technique to simulate the typical profiles within the South Sub-Pit and analyze the influence of tectonic evolution on hydrocarbon source rock formation and trap formation.The formation simulation parameters were compiled,and the thermal evolution history of hydrocarbon source rocks and hydrocarbon transport and accumulation history of MXN South Sub-Pit were simulated to explore the differences of thermal evolution process in the study area.Finally,the production,geological and seismic data were combined to summarize the oil and gas formation conditions in the study area and to predict the favorable areas for oil and gas exploration comprehensively,laying the foundation for the next step of oil and gas exploration.The main understanding of the study:(1)The tectonic evolution of the South Subduction Zone is roughly divided into three stages,namely the Faulting Stage,the Faulting Stage and the Passing Stage.The extensional activity is strong during the fracture phase,and the depression is subsiding as a whole during the tectonic transition of the depression phase.The influence of tectonic movements on the deposition of strata and the transport and reservoir formation of oil and gas varies from era to era.(2)The thermal history of the study profile was simulated,indicating the beginning of the low maturation stage at the end of the Eocene(38 Ma)in the MXN South Subterranean.The organic matter maturity of hydrocarbon source rocks in the study area gradually increases from east to west during the same geological era,and the present-day hydrocarbon source rocks enter the maturity stage in the west as a whole and transition to the immature-low maturity stage in the east.The western part of the southern subpet possesses a higher degree of thermal evolution than the eastern part.(3)The tectonic evolution process,hydrocarbon source rock maturity evolution history and hydrocarbon formation conditions are comprehensively analyzed,the hydrocarbon distribution law is summarized,and it is concluded that the study area is mainly a near-source vertical penetration type hydrocarbon formation mode,and two formation favorable zones are summarized in South Subway,which are the western fracture zone type I favorable zone and western type II favorable zone.