THE OIL SOURCE AND ITS SIGNIFICANCE FOR PETROLEUM EXPLORATION IN STRUCTURAL BELTⅠIN THE HUANGHUA DEPRESSION, THE BOHAI BAY BASIN

Some stripped oil stream has been found in Dongying Formation in the Well Baidong 2×1 lying in the structural belt Ⅰ of the Huanghua Depression,the Bohai Bay Basin.The structural belt Ⅰ is large in scale with lower degree of exploration.The geochemical characters of the crude oil showed that the oil was a light and mature crude oil with middle-high content of wax.The primary gonane components are cholane and isocholestane,and the distribution of the C₂₇,C₂₈ and C₂₉ gonane is just like of an appreciably anisomerous "V".And the secondary gonane components are some diasteranes and 4-methyl gonane.The content of tricyclic terpane is appreiably lower than that of pentacyclic terpane.The content of gammacerane is high.And the content of Ts,C₂₉Ts and C₃₀ rearrangement hopanoid is higher.The distribution character of biomarkers shows that oil source is a mixture of homoneneae and terrigenous plants in brackish-saline water.This indicates that the crude oil was originated from the saline lake source rock in the lower Es1,or Es3 in the Qikou Sag.Structural belt Ⅰ is close to the petroleum generative sag,and the reservoirs conditions are good,so it's favorable for petroleum exploration.