Molecular insight into the oil displacement mechanism of CO_(2) flooding in the nanopores of shale oil reservoir

作     者：Xiao-Hu Dong Wen-Jing Xu Hui-Qing Liu Zhang-Xing Chen Ning Lu 

作者机构：State Key Laboratory of Petroleum Resources and EngineeringChina University of PetroleumBeijing102249China MOE Key Laboratory of Petroleum EngineeringChina University of PetroleumBeijing102249China Department of Chemical and Petroleum EngineeringUniversity of CalgaryCalgaryAlbertaT2N 1N4Canada 

出 版 物：《Petroleum Science》 (石油科学（英文版）)

年 卷 期：2023年第20卷第6期

页      面：3516-3529页

核心收录：

学科分类：0820[工学-石油与天然气工程] 08[工学] 0703[理学-化学] 082002[工学-油气田开发工程] 

基　　金：supported by the National Natural Science Foundation of China(No.52004303) Beijing Natural Science Foundation(No.3212020). 

主　　题：Displacement behavior Nanopores NEMD simulation Shale oil CO_(2) Kerogen 

摘      要：With the increasing demand for petroleum,shale oil with considerable reserves has become an important part of global oil resources.The shale oil reservoir has a large number of nanopores and a complicated mineral composition,and the effect of nanopore confinement and pore type usually makes the effective development of shale oil challenging.For a shale oil reservoir,CO_(2) flooding can effectively reduce the oil viscosity and improve the reservoir properties,which can thus improve the recovery performance.In this study,the method of non-equilibrium molecular dynamics(NEMD)simulation is used to simulate the CO_(2) flooding process in the nanoscale pores of shale oil reservoir.The performance difference between the organic kerogen slit nanopore and four types of inorganic nanopores is discussed.Thus,the effects of nanopore type and displacement velocity on the nanoscale displacement behavior of CO_(2) are analyzed.Results indicate that the CO_(2) flooding process of different inorganic pores is different.In comparison,the displacement efficiency of light oil components is higher,and the transport distance is longer.The intermolecular interaction can significantly affect the CO_(2) displacement behavior in nanopores.The CO_(2) displacement efficiency is shown as montmorillonite,feldsparquartzcalcitekerogen.On the other hand,it is found that a lower displacement velocity can benefit the miscibility process between alkane and CO_(2),which is conducive to the overall displacement process of CO_(2).The displacement efficiency can significantly decrease with the increase in displacement velocity.But once the displacement velocity is very high,the strong driving force can promote the alkane to move forward,and the displacement efficiency will recover slightly.This study further reveals the microscopic oil displacement mechanism of CO_(2) in shale nanopores,which is of great significance for the effective development of shale oil reservoirs by using the method of CO_(2) injection.