Study On The Pool-forming Mechanism And Models Of Neogene Reservoirs In Baxian Depression

With the comprehensive research methods of petroleum geology, this paper gives a comprehensive research on the Forming Mechanism and Models of Neocene Reservoirs in Wenan slope, Baxian Depression. Through the research on the geologic reservoir characteristic, geochemical characteristics of source rock and oil-source correlation, passage system and migration direction, accumulation models and main controlling factors, has obtained the following results and recognitions:The results show that lower Es1, Es3 and Es4 are effective source rocks;the hydrocarbon generation of source rocks are simulated, and it is concluded that Es1 source rock generate low mature oil in the late of Ed epocd, Wenan slope zone does not have hydrocarbon generation capacity and it's Neocene hydrocarbon belonging to other sources. Neocene hydrocarbon distributes in Ng formation of outer belt, Wenan slope zone which mostly is fault nose reservoirs or fault-block reservoirs. The oil-source correlation indicates Neogene hydrocarbon froming lower Es1 source rock.The pathway system is consisted of three parts in the study area:permeable sand bodies, faults and unconformities. Effective passage system is identified through researching crude oil properties,nitrogen compounds,fluid properties, hydrocarbon show and effective migration space. Hydrocarbon migration in the manner of ladder stairs which layer becoming new gradually with the rising of migration distance, finally, accumulate in Neogene formation of Wenan slope. Based on this, one pool-forming model is established: tepladder-lateral migration model. At last, it is concluded that the main controlling factors of Neogene oil pool-forming in Baxian Sag are the regional tectonic background,the effective pathways and the preservation conditions.