Study On Reservoir-forming Dynamics And Migration Pathway Of Yanchang-9 Reservoir In Dingbian Area

The study area of this paper is Dingbian area,northwest of Ordos Basin.The target section is Chang-9 formation of Yanchang formation of Triassic,based on the data of drilling,core,logging,laboratory analysis and so on in the study area.By using a series of analysis techniques related to the comprehensive analysis of reservoir-forming models,the reservoir-forming dynamics and migration paths of Chang-9 reservoir in Dingbian area are comprehensively analyzed and studied.The comprehensive conditions of reservoir formation,the source of oil and gas and the types of oil and gas reservoirs are analyzed firstly,and then the reservoir forming period,the identification of reservoir forming dynamics,the origin of abnormal high pressure,the migration mode,the characteristics of migration path and the division of migration and accumulation system are studied in detail.Through the research,it can be concluded that: research The oil source of Chang-9 formation is Chang-7 source rock,which belongs to the model of upper generation and lower reservoir,and the main reservoir types are lithologic-structural reservoir,structural-lithologic reservoir and lithologic reservoir.The filling time of oil in the reservoir is middle-late stage of early Cretaceous,and the main reservoir-forming period is 130 Ma ±;The abnormal high pressure in Chang-9 reservoir is hydrocarbon-generating overpressure,and the reservoir-forming power is mainly the residual pressure between Chang-7 source rock and Chang-9 reservoir.The pressure difference is above 5-10 MPa,which is the downward migration power.The vertical migration path of oil and gas is mainly fractures,and a large number of high angle fractures are the efficient system of petroleum migration,while the oil reservoirs from Chang-7 to Chang-9 are longitudinally developed.The superimposed pore-type connected sand body is also an effective channel for oil and gas migration.