Optimal design of gas injection development method for enhanced recovery in terrestrial shale oil reservoir

• Published in: Frontiers in energy research 2024-04, Vol.12
• Main Authors: Cui, Xiaoyu, Chen, Zhewei, Wang, Rui, Han, Yi, He, Xujiao, Lei, Zhengdong
• Format: Article
• Language: English
• Subjects: enhanced oil recovery; gas injection; nuclear magnetic resonance (NMR); numerical simulation; terrestrial shale oil
• ISSN: 2296-598X; 2296-598X
• DOI: 10.3389/fenrg.2024.1397417

This study investigates the shale oil drainage characteristics from the Gulong Sag, The objective is to clarify the development method for effective recovery enhancement of terrestrial shale oil. The investigation employs elastic depletion, CO 2 displacement, and CO 2 huff and puff coupled with nuclear magnetic resonance (NMR) measurements and numerical simulation methods. The study found that the elastic depletion, CO 2 displacement, and CO 2 huff and puff utilization efficiencies were 17.4%, 18.87%, and 21%, respectively. The study evaluated the oil drainage efficiency of different pore sizes in elastic depletion and CO 2 huff and puff modes. The results demonstrated a clear trend in the order of micropore, mesoporous and macropore, with micropores exhibiting the highest oil drainage efficiency due to gas channeling during CO 2 displacement. The use of CO 2 huff and puff has been shown to improve oil drainage efficiency by 6.02%∼9.2% for different pore sizes. The numerical simulation optimization results suggest an injection volume of 3,000 t per round per well, an injection rate of 100 t/d, and a soaking time of 20 d for optimal CO 2 huff and puff injection. This will increase oil production by 65,000 m³, resulting in an overall improvement of 24%. The study results provide a strong theoretical foundation for improving the recovery rates of terrestrial shale oil and gas through injection.