Distribution Of Effective Hydrocarbon Source Rocks And Hydrocarbon Generation And Expulsion Characteristics Of 3rd Member Shahejie Formation Of Linnan Subsag

The structure of Linnan subsag is complex,the distribution range of oil and gas is wide,the formation process of oil and gas reservoirs is complex.With the increased level of exploration,the concealment reservoirs are becoming increasingly difficult to be dicovered.Es₃ is the most principle hydrocarbon source bed system in Linnan subsag.So far,the evaluation of hydrocarbon source rocks is not precise enough,also the study of hydrocarbon source rock characteristics and hydrocarbon generation is insufficient.So it is significant to further evaluate the geochemical characteristics,determine the distribution of effective source bed,and analyze the hydrocarbon generation and expulsion features to improve the success rate of oil and gas discovery in Linnan subsag.In this article,the lithological characteristics of the main hydrocarbon source rocks are analyzed by means of different lithology data and corresponding organic matter abundance.Through comprehensive evaluating organic geochemical index of source bed from different depositional environment,It is concluded that the quality of the whole source rocks of Es₃ is high,and the hydrocarbon source bed of Es₃³ in Depression center belongs to high-quality source rocks.Inversion of TOC by multivariate linear regression method,etc.,comprehensive determination of TOC lower limit of hydrocarbon expulsion threshold by hydrocarbon generation potential method,etc.,it is clear that the effective source rocks are widely distributed in the study area,especially in the Es₃³,with the thickest deposition in the depression center.Analysis the typical single well Burial history,hydrocarbon generation and expulsion characteristics by using Basin Mod1D.Study on hydrocarbon generation and expulsion characteristics of source rocks in the Es₃formation by using hydrocarbon potential method method to establish hydrocarbon generation and expulsion profile.it is found that the maximum hydrocarbon expulsion and generation intensity is in sediment centers of the lower section.The historical accumulative hydrocarbon expulsion amounts of the upper,middle and lower sub-member of ES₃ with 5.8×10⁸t,6.2×10⁸t and10.8×10⁸t is calculated by the hydrocarbon expulsion intensity map and the corresponding formula.