Oil-Gas Source and Accumulation Characteristics of Paleogene in Bonan Sub-Sagin Shengli Oil Field

The distribution and characteristic of oil and gas in Bonan sub-sag in Shengli oil field are described.The oil-gas source is determined through the biomarker features of biomarkers,and the process of the oil-gas accumulation is analyzed.The research indicates that the oil-gas evolution stages between the step-fault zone and the deep zone in Bonan sub-sag are different,due to different buried depths of source rocks.The oil and gas in the 3rd and 4th members of the Shahejie formation in this sub-sag are of nature with both source and reservoir.In the step-fault zone oil-gas is accumulated in one phase,with low maturity;in the deep zone there exist two processes of petroleum accumulation,but mainly trapping the gas generated at wet gas period,with high dry coefficient and stepped trapping features.