| The 3rd member of Shahejie Formation is the main hydrocarbon source rock of Dongpu sag,it is crucial to evaluate it deeply,determine the effective hydrocarbon source rock and analyse the hydrocarbon generation and expulsion characteristics of this member to improve the oil and gas exploration success rate and the discovery rate of Dongpu sag.This study fully absorb all aspects of the forefathers'research results,based on different color,different sedimentary environment of mudstone geochemical indicators,to determine that the main hydrocarbon source rocks is darker black,dark gray,gray mudstone and shale.Through comprehensive evaluating organic matter abundance,type and maturity of hydrocarbon source rock from three different depositional environment,found quality of the overall 3rd member hydrocarbon source rocks is good,and salt district of the lower section within the 3rd member of Shahejie Formation belongs to high-quality hydrocarbon source rocks.By applying the theory of hydrocarbon expulsion threshold to analyse the distribution of effective hydrocarbon source rock,it develops widely overall the study area,especially in salt district of the lower section.Through the analysis of different sedimentary environment including salt area,transition area and salt-free area source rocks hydrocarbon generation and expulsion characteristics by using modules?1D?BasinMod of PRA basin simulation software,it is found that the hydrocarbon expulsion threshold Ro of 0.85%,0.78%and 0.7%.There are three sections including the upper,middle and lower with the corresponding historically accumulative hydrocarbon generation amounts of 33.2×108t,124.8×108t,and 134.7×108t,and accumulative hydrocarbon expulsion amounts of 15.3×108t,69×108t and 79×108t. |
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