Open AccessExperimental investigation on influencing factors of CO 2 huff and puff under fractured low‐permeability conditions
Author(s) -
Li Binfei,
Bai Hao,
Li Aishan,
Zhang Liaoyuan,
Zhang Qiliang
Publication year - 2019
Publication title -
energy science and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.638
H-Index - 29
ISSN - 2050-0505
DOI - 10.1002/ese3.376
Subject(s) - permeability (electromagnetism) , petroleum engineering , fracture (geology) , enhanced oil recovery , tight oil , geology , geotechnical engineering , materials science , chemistry , oil shale , paleontology , biochemistry , membrane
The fracture system is a vital component of fractured low‐permeability reservoirs. The presence of fractures can improve reservoir flow capacity and injected carbon dioxide ( CO 2 ) utilization, thus leading to higher oil recovery. In this study, the effects of the presence of fracture, fracture morphology, soaking time, and CO 2 injection volume on CO 2 huff and puff were investigated through 11 low‐permeability cores with different properties. The experimental results indicated that the presence of fractures enhanced cyclic oil recovery and increased the effective cycle numbers during CO 2 huff and puff in low‐permeability cores. Moreover, compared with low‐permeability cores without fractures, ultimate oil recovery of CO 2 huff and puff was risen up by ~11% in fractured cores. Longer soaking time was conducive to enhancing ultimate oil recovery of CO 2 huff and puff in fractured low‐permeability cores, but the excessive soaking time had little effect on ultimate oil recovery. Meanwhile, excessive CO 2 injection volume did not significantly improve the performance of CO 2 huff and puff, but it did reduce the CO 2 utilization. Moreover, gravity caused the produced oil to deposit on the bottom surface of the blowout end of the fracture, which made oil recovery of the core with a horizontal fracture slightly higher (~7%) than that of the core with a vertical fracture. In addition, variation in the intersection angle of fractures had little effect on ultimate oil recovery of CO 2 huff and puff in fractured low‐permeability cores. It, however, did change the conductivity of the entire core, thus affecting oil recovery during the first two cycles remarkably.