Classification And Evaluation Of Petroleum System In The East Of Jinhu Depression

Based on the data of geology, geochemistry and geophysics, adopting the comprehensive research method, this paper gives classification and evaluation of petroleum system in the east of Jinhu depression. On the ground of dissecting the static elements of petroleum system(source rock, reservoir, seal and migration pathway), the paper puts emphasis on the dynamic process of hydrocarbon accumulation formation(trap formation and generation, migration, accumulation and preservation of hydrocarbon). Through the research on the major hydrocarbon generation and expulsion history of source rock, bubble point pressure of reservoirs, and the formation of entrapments, the major pool-forming periods in the east of Jinhu depression has been analyzed, it is deemed that the late Sanduo stage in Palaeogene is key moment of petroleum system. Based on detailed oil-source correlation, the relationship between source rock and oil and gas accumulation has been illustrated further. And the viewpoint that the study area has two groups of effective source rock(fu-4 and fu-2) and tow kinds of oil has been put forward. The study area has been divided into two petroleum systems, which forms a compound petroleum system. Taking the pod of source rock as center, the system can be divided into tow composite subsystems and four subsystems. According to the concept and division rules of petroleum migration-accumulation formation system, the study area can be divided into ten accumulation systems.Through the study of quantitative simulation of petroleum system and hierarchy evaluation of fuzzy method, quantitative evaluation system and index of petroleum system are established.The Longgang subsystem is considered as the best for oil and gas accumulation; the Bianminyang and circumference accumulation formation system has the best conditions for oil and gas accumulation. The paper systematically summarizes five accumulation formation modes in the east of jinhu depression, and analyzes the distribution rules and controlling factors of oil and gas.