Effect of petroleum chemical fraction and residual oil content in saline lacustrine organic-rich shale: A case study from the Paleogene Dongpu Depression of North China  

作　　者：Chen-Xi Zhu Fu-Jie Jiang Peng-Yuan Zhang Zhao Zhao Xin Chen Yu-Qi Wu Yuan-Yuan Chen Wei Wang Ze-Zhang Song Tao Hu Tian-Wu Xu Yong-Shui Zhou 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing,102249,China [2]China University of Petroleum(Beijing),Beijing,102249,China [3]Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,100191,China [4]Tianjin Branch of CNOOC Ltd,Tianjin,300459,China [5]Shenzhen Branch,CNOOC China Limited,Shenzhen,Guangdong,518000,China [6]Zhongyuan Oilfield Branch,SINOPEC,Henan,457001,China

出　　处：《Petroleum Science》2023年第2期649-669,共21页石油科学（英文版）

基　　金：funded by the National Natural Science Foundation of China (NSFC) (41872128);the Science Foundation of China University of Petroleum, Beijing (No. 2462020YXZZ021).

摘　　要：Halite and gypsum minerals in saline shale make the retention mechanism and chemical fractionation of residual oil unique. The Dongpu Depression in North China is a typically saline lacustrine basin with developing halite and gypsum. The effect of gypsum minerals on residual oil content and chemical fractionation remains unclear. In this study, shale samples with different gypsum contents were used in organic geochemical experiments, showing that the high total organic matter (TOC) content and type II kerogen leads to a high residual oil content, as shown by high values of volatile hydrocarbon (S1) and extractable organic matter (EOM). XRD and FE-SEM result indicate that the existence of gypsum in saline shale contributes to an enhanced pore space and a higher residual oil content in comparison to non-gypsum shale. Additionally, the increase in the gypsum mineral content leads to an increase in the saturated hydrocarbon percentage and a decrease in polar components percentage (resins and asphaltene). Furthermore, thermal simulation experiments on low-mature saline shale show that the percentage of saturated hydrocarbons in the residual oil is high and remains stable and that the storage space is mainly mesoporous (> 20 nm) in the oil expulsion stage. However, the saturated hydrocarbons percentage decreases rapidly, and oil exists in mesopores (> 20 nm and < 5 nm) in the gas expulsion stage. In general, gypsum is conducive to the development of pore space, the adsorption of hydrocarbons and the occurrence of saturated hydrocarbon, leading to large quantities of residual oil. The data in this paper should prove to be reliable for shale oil exploration in saline lacustrine basins.

关 键 词：Oil fractionation Residual oil Saline lacustrine shale The Dongpu Depression 

分 类 号：TE34[石油与天然气工程—油气田开发工程]