The source rocks of the lower part of Member 3, Shahejie Formation from the Well Niu-38 in the Dongying Depression, with a deep water lake facies, was deposited in a highstand system tract. Up to the middle part of Member 3 of the Shahejie Formation, the sedimentary facies changed to be a prodelta facies in a lowstand system tract. In such a sedimentary environment, different kerogen types in the source rocks were formed from the lower part to the middle part of the member. The source rocks in the lower part were rich in high contents of organic matter and type Ⅰ of kerogen, which were believed as effective source rocks (high generation and expulsion of hydrocarbons) in the depression. The source rocks in the middle part were in low contents of organic matter and type Ⅱ2 or type Ⅲ kerogen, regarded as ineffective ones. Although the source rocks in the lower part were highly heterogeneous in their organic matter contents and kerogen types, their capacities of hydrocarbon generation and expulsion might be quite different: the higher TOC and the better type of kerogen, the more quantity of hydrocarbons generated and expulted from the source rocks. A new method for predicting the quantities of the hydrocarbon generation and expulsion was presented in this paper. The prediction results showed that the quantities of hydrocarbon generation were differentiated in three decimal scales, which were corresponding to strong heterogeneity in the source rocks. The heterogeneity was believed as a result of the lacustrine cyclothemic sedimentation and the lake level fluctuation.
Chen Zhonghong,Zha Ming,Jin Qiang. AN INVESTIGATION ON GENERATION AND EXPULSION OF HYDROCARBON FROM SOURCE ROCKS OF THE SHAHEJIE FORMATION IN THE WELL NIU-38, DONGYING DEPRESSION[J]. Chinese Journal of Geology, 2004, (3): 356-366.