Experimental study of enhanced oil recovery by CO_(2) huff-n-puff in shales and tight sandstones with fractures  

作　　者：Chao-Fan Zhu Wei Guo You-Ping Wang Ya-Jun Li Hou-Jian Gong Long Xu Ming-Zhe Dong 

机构地区：[1]College of Construction Engineering,Jilin University,Changchun 130026,Jilin,China [2]School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,China [3]Petroleum Exploration and Production Research Institute,Sinopec,Beijing 100083,China [4]Department of Chemical and Petroleum Engineering,University of Calgary,Calgary,AB T2N 1N4,Canada

出　　处：《Petroleum Science》2021年第3期852-869,共18页石油科学（英文版）

基　　金：We gratefully acknowledge the National Key R&D Program of China(Grant No.2019YFA0705502,Grant No.2019YFA0705501);the fnancial support from the Shandong Provincial Natural Science Foundation(ZR2019QEE037,ZR2019MEE058);the Fundamental Research Funds for the Central Universities(17CX05005,18CX02104A).

摘　　要：The fractures and kerogen,which generally exist in the shale,are signifcant to the CO_(2) huf-n-puf in the shale reservoir.It is important to study the efects of fractures and kerogen on oil recovery during CO_(2) huf-n-puf operations in the fracture-matrix system.In this study,a modifed CO_(2) huf-n-puf experiment method is developed to estimate the recovery factors and the CO_(2) injectivity in the fractured organic-rich shales and tight sandstones.The efects of rock properties,injection pressure,and injection time on the recovery factors and CO_(2) usage efciency in shales and sandstones are discussed,respectively.The results show that although the CO_(2) injectivity in the shale is higher than that in the sandstone with the same porosity;besides,the recovery factors of two shale samples are much lower than that of two sandstone samples.This demonstrates that compared with the tight sandstone,more cycles are needed for the shale to reach a higher recovery factor.Furthermore,there are optimal injection pressures(close to the minimum miscible pressure)and CO_(2) injection volumes for CO_(2) huf-npuf in the shale.Since the optimal CO_(2) injection volume in the shale is higher than that in the sandstone,more injection time is needed to enhance the oil recovery in the shale.There is a reference sense for CO_(2) huf-n-puf in the fractured shale oil reservoir for enhanced oil recovery(EOR)purposes.

关 键 词：Shale Tight sandstone CO_(2)huf-n-puf Fracture Injectivity of CO_(2) 

分 类 号：TE357.7[石油与天然气工程—油气田开发工程]