Hydrocarbon Generation And Expulsion Characteristics Of Source Rocks In The 3^rd Member Dongying Formation And The 1^st Member Shahejie Formation Of Nanpu Sag

There are three sets of hydrocarbon source rocks in Nanpu sag of Bohai Bay basin.At present,the research and understanding of source rocks in the 3^rd member of Shahejie Formation is relatively clear,but the understanding of hydrocarbon generation and expulsion capacity and effectiveness of source rocks in the 1^st member of Shahejie Formation and the 3^rd member of Dongying Formation is insufficient,which leads to the inaccurate prediction of hydrocarbon resource potential in Nanpu sag and restricts the exploration decision.In order to judge the effectiveness of hydrocarbon source rocks in the 1^st member of Shahejie Formation and the 3^rd member of Dongying Formation of Nanpu sag,the organic geochemical indexes of single well hydrocarbon source rocks were calculated and evaluated by collecting core samples of exploration Wells and using the weighted average method.Base on this,by means of the combination and verification of single well analytical test data with seismic inversion,sedimentary facies,tectonic burial depth and other data"point-surface",plane prediction and evaluation of hydrocarbon source rock thickness,organic matter abundance,organic matter type and thermal evolution degree of source rocks were carried out.Based on the above results,the hydrocarbon expulsion characteristics of source rocks and the lower limit of TOC in the 3^rd member of Donging formation and the 1^st member of Shahejie Formation are analyzed by using the method of hydrocarbon generation potential.The hydrocarbon expulsion threshold of source rocks was determined,and the existence of effective source rocks in the 3^rd member of Donging formation and the 1^st member of Shahejie Formation was determined.Based on the investigation of strata age and geological and thermodynamic parameters in Nanpu sag.Combined with single well geological stratification data,the Basin Mod basin simulation software was used to simulate the burial history and thermal history of single well,and the hydrocarbon generation potential method was also applied to the 3^rd member of Donging formation and the 1^stmember of Shahejie Formation In order to analyze the hydrocarbon generation and expulsion characteristics of source rocks.The results show that the main hydrocarbon expulsion period of source rocks in the 3^rd member of Dongying formation is the sedimentary period of Minghuazhen formation,with the vitrinite reflectance corresponding to the hydrocarbon expulsion threshold is 0.82%and the depth is 3620m.The vitrinite reflectance corresponding to the hydrocarbon expulsion threshold of the 1^stmember of Shahejie Formation is 0.83%and the corresponding depth is 3690m.The hydrocarbon generation and expulsion in the 3^rd member of Dongying formation source rocks are 13.79×10⁸t and 5.52×10⁸t respectively.The hydrocarbon generation and and 11.18×10⁸t respectively.Generally speaking,the source rocks of the 3^rd member of Dongying formation and the 1^st member of Shahejie formation can discharge hydrocarbon,and have a certain amount of hydrocarbon expulsion,which has a preferable resource prospect.