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- Title
Enhancing shale gas recovery by carbon dioxide injection: A method of carbon capture, utilization and storage (CCUS).
- Authors
Sun, Ying; Zuo, Luo; Li, Xiaolong; Liu, Xiaoqiang
- Abstract
CO 2 injection in shale gas reservoir can not only increase the production of shale gas, but also realize carbon dioxide capture, utilization and storage. At present, most experimental studies of CO 2 injection in shale are carried out by conventional core experiments. However, it is difficult to analyze the process of CO 2 replacing shale gas and adsorption in shale pores on microscopic scale. In this study, nuclear magnetic resonance (NMR) technology is used to analyze the migration and conversion of CH 4 in process of CO 2 injection and depressurization production. Based on above experiments, microscopic mechanism of competitive adsorption of CH 4 and CO 2 during CO 2 injection is clarified, and the stimulation mechanism of CO 2 injection to improve shale gas recovery is further proposed. The results show that CH 4 preferentially exists in form of adsorption state in shale. When CH 4 adsorption amount reaches a certain degree, CH 4 gas in form of free state gradually appears. During depressurization stage, further depressurization failed to promote the desorption of adsorbed gas when pressure reduced to 3 MPa. Therefore, adsorbed CH 4 gas still exists after depressurization production. Shale has stronger adsorption capacity for CO 2 than CH 4. CO 2 can replace CH 4 adsorbed on the pore surface, and promote the desorption of adsorbed CH 4 gas to free state. CO 2 has the best displacement effect on adsorbed CH 4 in pores with diameter of 15.04–21.62 nm, but it fails to replace CH 4 in pores with diameter less than 1.08 nm. The competitive adsorption of CO 2 and CH 4 can effectively promote the further desorption of residual adsorbed CH 4 gas after depressurization, and significantly improve the cumulative shale gas production.
- Subjects
CARBON dioxide injection; OIL shales; SHALE gas reservoirs; CARBON sequestration; SHALE gas; NUCLEAR magnetic resonance
- Publication
Process Safety & Environmental Protection: Transactions of the Institution of Chemical Engineers Part B, 2023, Vol 179, p484
- ISSN
0957-5820
- Publication type
Article
- DOI
10.1016/j.psep.2023.09.049