| Based on the research of structure, depositional and heating power condition to formation of petroleum system in the north of Songliao Basin, petroleum system of middle and shallow strata are divided by oil sources contrast and using source rock and caprock.It was considered that K1qn～F.Y～K1qn,K1qn+K1n1+2～S.P.G～K1n1+2,and K1n3+4～H～K1n5 are three petroleum system in the vertical direction of middle and shallow strata in north of Songliao Basin. The reservoir types of the K1qn～F.Y～K1q oil-bearing system are mainly fault-lithologic hydrocarbon reservoir, The four factors that control oil accumulation and distribution are the distribution of effective source rock ,good caprock, overpressure sandbody in low water level and development of fault. The key period of oil accumulation are the end of K2m.The main oil accumulation are the oil that flow backward into fault-lithologic or fault-trap .The two types of oil reservoir in the K1qn+K1n1+2～S.P.G～K1n1+2 petroleum system are anticline and fault, where there are abundant oil and gas.The oil accumulation and distribution are mainly controlled by source rock,palaeostructrue,sandbody and structure.The key period for oil accumulation is the end of K2m sediment.The oil accumulation are oil that migrate into structural trap and oil in source rock migrate into fault-barrier trap.The petroleum system of K1n3+4～H～K1n5 is mainly fault nose , mainly develop in the west of Daqing placanticline.Oil accumulation and distribution are mainly controlled by effective source rock,fault and control action that among sandbody,fault and structure.The oil and gas accumulation are oil from oil-generating strata below and reservoir above that migrate along fault into trap sealed by fault. K1qn F.Y K1qn petroleum system are divided into eight subsystem field in terms of fluid potential field partition gutter, while K1qn+K1n1+2～S.P.G～K1n1+2 eight and K1n3+4～K1n5 is five.it's considered thatâ… ,â…¡,â…¢,â…£oil gas-bearing subsystem of K1qn～F.Y～K1qn and K1qn+K1n1+2～S.P.G～K1n1+2 K1n3+4～H～K1n5 are best .Based on the research of formation and evolution of source rock,fault and caprock, it considerd that the petroleum system in the middle and shallow strata of in the north of Songliao Basin , the fault of long term active and middle later period are open at the end of K1n and K2m and N which leads to the formation of K1sh+K1yc+K1qn～F.Y～K1qn petroleum system caused by the extension of K1qn～F.Y～K1qn and"mixture source"in K1qn～F.Y～K1qn.K1qn+K1n1+2-S.P.G～K1n1+2 and K1n3+4～H～K1n5 petroleum system formed K1qn+K1n1+2+K1n3+4～H～K1n5 petroleum system, which leads to one strata with multiple oil accumulation in Heidimiao reservoir. The main reason are caused by petroleum system that control the source of oil and gas, migration stratigraphic position,accumulation period .it's considered that the favorable place for oil accumulation and distribution of K1qn～F.Y～K1qn petroleum system mainly distributed Qijia～Gulong depression,Daqing placanticline and west slope.,and Sanzhao depression and Chaochang place. While for K1qn+K1n1+2～S.P.G～K1n1+2 the favorable place for oil accumulation and distribution are Sanzhao depression,Daqing placanticline ,Qijia～Gulong depression, while for K1n3+4～H～K1n5 favorable place are Qijia～Gulong depression and middle and south of Daqing placanticline.
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