Impact of volcanism on the formation and hydrocarbon generation of organic-rich shale in the Jiyang Depression, Bohai Bay Basin, China  

作　　者：Jia-Hong Gao Xin-Ping Liang Zhi-Jun Jin Quan-You Liu Chang-Rong Li Xiao-Wei Huang Ju-Ye Shi Peng Li 

机构地区：[1]State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development,Institute of Energy,Peking University [2]Petroleum Exploration and Production Research Institute,SINOPEC,Beijing,100871 China [3]School of Energy Resources,China University of Geosciences Beijing,100083 China

出　　处：《Petroleum Science》2024年第3期1539-1551,共13页石油科学（英文版）

基　　金：the financial support from the National Natural Science Foundation of China(42172151,42090025,41811530094,and 41625009);the China Postdoctoral Science Foundation(2021M690204);the National Key Research and Development Program(2019YFA0708504&2023YFF0806200)。

摘　　要：Globally,most organic-rich shales are deposited with volcanic ash layers.Volcanic ash,a source for many sedimentary basins,can affect the sedimentary water environment,alter the primary productivity,and preserve the organic matter(OM)through physical,chemical,and biological reactions.With an increasing number of breakthroughs in shale oil exploration in the Bohai Bay Basin in recent years,less attention has been paid to the crucial role of volcanic impact especially its influence on the OM enrichment and hydrocarbon formation.Here,we studied the petrology,mineralogy,and geochemical characteristics of the organic-rich shale in the upper submember of the fourth member(Es_(4)^(1))and the lower submember of the third member(Es_(3)^(3))of the Shahejie Formation,aiming to better understand the volcanic impact on organic-rich shale formation.Our results show that total organic carbon is higher in the upper shale intervals rich in volcanic ash with enriched light rare earth elements and moderate Eu anomalies.This indicates that volcanism promoted OM formation before or after the eruption.The positive correlation between Eu/Eu*and Post-Archean Australian Shale indicates hydrothermal activity before the volcanic eruption.The plane graph of the hydrocarbon-generating intensity(S1+S2)suggests that the heat released by volcanism promoted hydrocarbon generation.Meanwhile,the nutrients carried by volcanic ash promoted biological blooms during Es_(4)^(1 )and Es_(3)^(3) deposition,yielding a high primary productivity.Biological blooms consume large amounts of oxygen and form anoxic environments conducive to the burial and preservation of OM.Therefore,this study helps to further understand the organic-inorganic interactions caused by typical geological events and provides a guide for the next step of shale oil exploration and development in other lacustrine basins in China.

关 键 词：Volcanic ash Hydrocarbon generation Organic-rich shale Shahejie Formation Jiyang Depression 

分 类 号：TE34[石油与天然气工程—油气田开发工程]