Thickness

among the structural parameters of source rocks

has relatively large influences on hydrocarbon expulsion efficiency.Source rocks can be divided into complete expulsion and incomplete expulsion types

according to the relative relation between the continuous thickness and the maximum effective expulsion thickness of source rocks.The development and spatial distribution features of abnormal pressures determine the spatial distribution of episodic expulsion.Based on the distribution of abnormal pressure and structural parameters of source rocks

the geologic models of effective source rocks can be divided into complete expulsion model

incomplete expulsion model and episodic expulsion model.The mathematical models of these 3 kinds of hydrocarbon-expulsion geologic models are derived from the concept of rhythmic layering and source rock heterogeneity.Actual calculation of the source rocks in Niu-38 well verifies that the new models improve the accuracy of calculation.