Liu Jiawei, Xie Mengke, Liu Dongchen, Cao Lieyan, Xie Shengyang, Chang Ying, Zhang Jian, Yang Xuefeng
Shale Gas Research Institute, PetroChina Southwest Oil & Gas Field Company, Chengdu 610051, China.
Sichuan Key Laboratory of Shale Gas Evaluation and Exploitation, Chengdu 610059, China.
ACS Omega. 2024 Jul 17;9(30):33111-33118. doi: 10.1021/acsomega.4c04464. eCollection 2024 Jul 30.
The technology of CO-enhanced gas recovery (CO-EGR) plays a pivotal role in the CCUS (Carbon Capture, Utilization, and Storage) industry, which helps to achieve a win-win situation of economic benefit and environmental benefit for gas fields. Shale gas reservoirs, with their unique geological and surface engineering advantages, are one of the most promising options for CCUS implementation. Focusing on shale formations within the mid-deep blocks of the Sichuan Basin, this study conducted competitive adsorption experiments using multicomponent gases. Through physical simulations and single-well numerical modeling, factors such as injection volume, timing, shut-in time, and huff-n-puff rounds were examined for their impact on recovery. The results show that the higher the CO content in the injected medium, the more pronounced advantage in gas adsorption on shale surfaces. Optimal performance was achieved with a CO content in the injection medium of 80% to 100%, an injection volume of 0.2-0.3 PV, a shut-in time exceeding 6 h, and a relatively delayed injection timing. The recovery in the first round of huff-n-puff was increased by 24.2% to 47.8%, which gave a full play to the role of huff-n-puff and achieved favorable benefits. Based on the middle-deep geological parameters, a single-well numerical simulation was established, which demonstrates that single-well EUR (estimated ultimate recovery) can be increased by 14.2% to 19.8% compared to gas wells without CO injection. This study provides essential guidance for the enhanced recovery in shale gas reservoirs through CO huff-n-puff.
CO 强化气藏采收率（CO-EGR）技术在碳捕集、利用与封存（CCUS）行业中发挥着关键作用，有助于气田实现经济效益与环境效益的双赢。页岩气藏因其独特的地质和地面工程优势，是实施 CCUS 最具潜力的选择之一。本研究聚焦于四川盆地中深层区块的页岩地层，开展了多组分气体的竞争吸附实验。通过物理模拟和单井数值模拟，考察了注入量、注入时机、关井时间和吞吐轮次等因素对采收率的影响。结果表明，注入介质中 CO 含量越高，在页岩表面的气体吸附优势越明显。注入介质中 CO 含量为 80%至 100%、注入量为 0.2-0.3PV、关井时间超过 6 小时且注入时机相对滞后时，可实现最佳性能。第一轮吞吐采收率提高了 24.2%至 47.8%，充分发挥了吞吐作用，取得了良好效益。基于中深层地质参数建立了单井数值模拟，结果表明，与未注入 CO 的气井相比，单井估计最终采收率（EUR）可提高 14.2%至 19.8%。本研究为通过 CO 吞吐提高页岩气藏采收率提供了重要指导。
