Geochemical Characteristics And Evaluation Of Hydrocarbon Generation Potential Of Chepaizi Source Rocks From Carboniferous

At the present stage,geochemical characteristics,hydrocarbon generation potential,hydrocarbon generation period and oil source contribution of Carboniferous source rocks in Chepaizi are not clear.In this paper,Carboniferous hydrocarbon source rocks in Chepaizi have been investigated in aspects of hydrocarbon generation potential and evolution characteristic.Combining with basin modeling,closed simulation has been taken on Carboniferous source rocks to analyze their hydrocarbon generation features at different evolution stages,and to rebuild their hydrocarbon generation and expulsion processes,which in turn,could help carry out oil source correlation based on detailed analysis of biomarker and isotope characteristics of hydrocarbon source rocks and crude oil.The effects of tuffaceous variations on the hydrocarbon generation potential have been evaluated additionallyThe result indicates that the Carboniferous hydrocarbon source rocks in Chepaizi are predominantly poor-good source rocks at mature-high mature stage,with low abundance of organic matter mainly in the types of III and II₂.Besides,the surrounding area,namely Sikeshu,has the possibility to regenerate hydrocarbon.It appears that tuff has certain influences on promoting the enrichment of algae and bacteria,enhancing the hydrocarbon generation ability of source rocks,and creating a reductive environment for preservation.Among western margin of Chepaizi block,Permian source rock is the major source of Carboniferous crude oil in eastern and central part,with Carboniferous and Jurassic synergizing the formation within central part.While for the western part,Jurassic source rocks account for the formation of crude oil,mostly light oil,with barely any contributions from other layers.