Wang Xing, Feng Zengchao, Zhou Dong, Zhang Bichuan
Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, People's Republic of China.
College of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, People's Republic of China.
ACS Omega. 2024 Apr 12;9(16):18099-18112. doi: 10.1021/acsomega.3c10059. eCollection 2024 Apr 23.
Permeability rebound and recovery are pivotal in determining the efficacy of coalbed methane (CBM) extraction and the impact of superheated water injection during thermally enhanced CBM extraction. Existing research predominantly focuses on the roles of effective stress and methane desorption shrinkage, often neglecting the critical influence of the temperature. Therefore, our study introduces a mathematical model incorporating heat-fluid-solid coupling and a permeability evolution model considering temperature variations. The model was used to analyze the phenomenon of permeability rebound and recovery during CBM extraction and the effects of various factors on it. The results show that the permeability rebound and recovery time increase with initial gas pressure but decrease with initial diffusion coefficient and permeability. Initial coal seam temperature has little effect on the permeability rebound time, which increases the recovery time. The permeability rebound value rises with the initial diffusion coefficient but falls with the initial gas pressure and permeability, and the coal seam temperature has little impact on it. In addition, whether to consider the temperature on the permeability evolution is compared. The results reveal that temperature impact causes an elevation in permeability rebound, prolongs rebound and recovery time, and reduces postrecovery permeability ratio compared to the scenario without temperature influence. Inspired by the law of permeability evolution, this paper discusses the impact of injection pressure and temperature on the effectiveness of superheated water injection in the initial stage of enhanced CBM recovery engineering practice. The findings offer valuable insights into selecting optimal injection parameters tailored to various coal seams.
渗透率回弹与恢复对于确定煤层气（CBM）开采效率以及热强化煤层气开采过程中注过热蒸汽的影响至关重要。现有研究主要关注有效应力和甲烷解吸收缩的作用，常常忽视温度的关键影响。因此，我们的研究引入了一个包含热 - 流 - 固耦合的数学模型以及一个考虑温度变化的渗透率演化模型。该模型用于分析煤层气开采过程中的渗透率回弹与恢复现象以及各种因素对其的影响。结果表明，渗透率回弹和恢复时间随初始气体压力增加而增加，但随初始扩散系数和渗透率降低。初始煤层温度对渗透率回弹时间影响较小，但会增加恢复时间。渗透率回弹值随初始扩散系数升高，但随初始气体压力和渗透率降低，且煤层温度对其影响较小。此外，比较了是否考虑温度对渗透率演化的影响。结果表明，与无温度影响的情况相比，温度影响会导致渗透率回弹升高，延长回弹和恢复时间，并降低恢复后的渗透率比值。受渗透率演化规律的启发，本文讨论了注汽压力和温度对强化煤层气开采工程实践初始阶段注过热蒸汽效果的影响。研究结果为针对不同煤层选择最佳注汽参数提供了有价值的见解。
