摘要
Crude oils from Dongying and Shahejie Formations of BZ35/36 structures in Huanghekou sag,Bohai Bay Basin are characterized by high density,high viscosity and high sulfur,these physical properties and geochemical features are quite different from crude oils in other structures of Huanghekou sag.The comparison and analysis of biomarkers,including Pr/Ph,C24Te/C26TT,C2920S/(20S+20R) and C29ββ/(ββ+αα) ratios,and gammacerane,show that sulfur-rich oils in these two structures have an affinity with the high-sulfur oil in Miaoxi sag adjacent to the eastern Huanghekou sag.The high-sulfur low-maturity crude oil of Miaoxi sag was charging from northeast to southwest,while the low-sulfur mature crude oil of Huanghekou sag was charging in the opposite direction.Because these sags had comparatively high hydrocarbon generative potential,crude oils derived from them gathered in BZ35/36 structures that lie in the hydrocarbon charging path.By analogy with the same type of high-sulfur crude oils,a preliminary conclusion can be drawn that source rocks of the sulfur-rich crude oils are formed in a dry climate and strongly reducing saline lake with abundant living beings.