Study on geochemical characteristics of crude oil from Bozhong sag in Bohai bay basin

There exist multi-types and abundant oil and gas resources in the basin of Bohai bay with.The system research of 19 oil samples from Bozhong sag reveals the difference of different crude oil,including physical propertied,chemical composition,distribution and composition of biomarkers,carbon isotope of normal-alkane.The research result shows that condensate oil,normal oil and biodegraded oil are contained in Bozhong sag.The condensate oil has low density,low viscosity,low wax-content,low nonhydrocarbon-content,low bitumen-content,low aromatic-hydrocarbon-content and high saturate-hydrocarbon-content;biodegraded oil has contrary characteristics.The abundance of dia-drimane of condensate oil and biodegraded oil is larger than that of 8β(H)-drimane.They has low-abundance of C24 tetracyclic terpane.The carbon isotope of normal alkane of crude oil is divided into two kinds: one has small value,which between-27.5‰ and-29.5‰;the other has big value,which between-24.0‰ and-27.5‰.