Abstract: A fully coupled fluid flow and geomechanics model is proposed for ECBM and CO2 underground storage with consideration of multi⁃component multi⁃process transportation in porous media to investigate the complicated geomechanical effects, and the corresponding numerical solver is developed. The effect of geomechanical effects and injection gas components on permeability and injection/production index were also investigated. The results indicate that both effective stress effect and matrix swelling/shrinkage can significantly affect porosity and permeability, but in opposite direction. Matrix swelling induced by CO2 injection can lead to about 90% loss in permeability around injector. The increasing of Young's modulus or decreasing of matrix Langmuir strain, will induce earlier CO2 breakthrough time and lower coalbed methane recovery and CO2 sequestration amount. These results can provide better methane production prediction and support high⁃efficient productivity improvement.

Key words: Coalbed methane, Enhanced recovery, Coupling effects of fluid flow and geomechanics, Matrix swelling/shrinkage, CO2 sequestration

摘要： 为准确表征煤层气藏强化开采过程中的复杂地质力学效应，同时考虑多孔介质全组份多过程物质运移特征，构建了煤层气藏强化开采全流固耦合数学模型，开发了相应的数值模拟算法，并据此进一步剖析了地质力学效应以及注入气组成对孔渗参数及注采指标的影响。结果表明，有效应力效应与基质膨胀/收缩作用均可显著地影响孔隙度与渗透率，但两者作用方向相反，注入CO2诱发的基质膨胀可使注入井附近渗透率损失近90%。随着杨氏模量的增大或者基质形变强度的降低，CO2突破时间提前，导致煤层气产量及CO2埋存量降低。研究成果可为煤层气产能准确预测及高效开发提供技术支持。

关键词: 煤层气, 强化开采, 流固耦合作用, 基质膨胀/收缩, CO₂埋存