Abstract

The fractures and kerogen, which generally exist in the shale, are significant to the CO2 huff-n-puff in the shale reservoir. It is important to study the effects of fractures and kerogen on oil recovery during CO2 huff-n-puff operations in the fracture–matrix system. In this study, a modified CO2 huff-n-puff experiment method is developed to estimate the recovery factors and the CO2 injectivity in the fractured organic-rich shales and tight sandstones. The effects of rock properties, injection pressure, and injection time on the recovery factors and CO2 usage efficiency in shales and sandstones are discussed, respectively. The results show that although the CO2 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 CO2 injection volumes for CO2 huff-n-puff in the shale. Since the optimal CO2 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 CO2 huff-n-puff in the fractured shale oil reservoir for enhanced oil recovery (EOR) purposes.

Details

Title
Experimental study of enhanced oil recovery by CO2 huff-n-puff in shales and tight sandstones with fractures
Author
Chao-Fan, Zhu 1 ; Guo, Wei 2 ; You-Ping, Wang 3 ; Ya-Jun, Li 4 ; Hou-Jian, Gong 4 ; Long, Xu 4 ; Ming-Zhe, Dong 5 

 Jilin University, College of Construction Engineering, Changchun, China (GRID:grid.64924.3d) (ISNI:0000 0004 1760 5735); China University of Petroleum (East China), School of Petroleum Engineering, Qingdao, China (GRID:grid.497420.c) (ISNI:0000 0004 1798 1132) 
 Jilin University, College of Construction Engineering, Changchun, China (GRID:grid.64924.3d) (ISNI:0000 0004 1760 5735) 
 Sinopec, Petroleum Exploration and Production Research Institute, Beijing, China (GRID:grid.418531.a) (ISNI:0000 0004 1793 5814) 
 China University of Petroleum (East China), School of Petroleum Engineering, Qingdao, China (GRID:grid.497420.c) (ISNI:0000 0004 1798 1132) 
 China University of Petroleum (East China), School of Petroleum Engineering, Qingdao, China (GRID:grid.497420.c) (ISNI:0000 0004 1798 1132); University of Calgary, Department of Chemical and Petroleum Engineering, Calgary, Canada (GRID:grid.22072.35) (ISNI:0000 0004 1936 7697) 
Pages
852-869
Publication year
2021
Publication date
Jun 2021
Publisher
KeAi Publishing Communications Ltd
ISSN
16725107
e-ISSN
19958226
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2544321172
Copyright
© The Author(s) 2020. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.