Geochemical characteristics of crude oil and oil-source correlation in Nanpu sag,Bohai Bay Basin

The types of crude oil formed in Nanpu sag were classified on the basis of delicate geochemical correlation.The correlation between crude oil and hydrocarbon source rocks was also researched by combined characteristics of biomarkers.It is shown that there are six types of the crude oils in Nanpu sag,which have different compositional characteristics.The type I oil occurs in the Nm and Ng in Liuzan,Gaoshangpu and Laoyemiao Oilfield.The type II oil occurs in Ed of Gaoshangpu,Laoyemiao and Beipu Oilfield.The type III oil occurs in Liuzan Oilfield and Gaoshangpu Oilfield in the north of Gaoliu fault.The type IV oil occurs in Ed reservoir.And the type V and VI oil occur in Ordovician reservoir.The results show that these three series of hydrocarbon source rocks have different contribution to different conformation.The oils of Liuzan Oilfield and part oil of Gaoshangpu Oilfield are mainly sourced from source rocks of Es3 in the north of Gaoliu fault,others are derived from Es1 and Ed3,partly from Es3.The oils of Laoyemiao and Beipu Oilfield are mainly formed from Es1 and Ed3,partly from Es3.The oils of beach area are mainly derived from Es1 and Es3.