【作者】 冯启言； 周来； 陈中伟； 刘继山；

【Author】 FENG Qiyan~(1,2*) ZHOU Lai~(1,2) CHEN Zhongwei~(3,4) LIU Jishan~(3,4) (1.School of Environment Science and Spatial Informatics, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China; 2. Jiangsu Key Laboratory of Resources and Environmental Information Engineering, Xuzhou 221008; 3. State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China; 4. Center for Petroleum and Energy Research, University of Western Australia, Perth, WA 6009, Australia)

【机构】 中国矿业大学环境与测绘学院； 江苏省资源环境信息工程重点实验室； 中国矿业大学深部岩土力学与地下工程国家重点实验室； 澳大利亚西澳大利亚大学石油与能源研究中心；

【摘要】 二氧化碳注入煤层处置后引入的是个复杂的CH₄-CO₂二元气体与煤体的气固耦合问题,耦合了二元气体竞争吸附、竞争扩散,气体渗流以及煤体变形过程。基于COMSOL Multiphysics建立了二元气固耦合的有限元数值模型,并应用数值模拟实验对二元气固耦合进行了机理分析。模拟结果表明:CO₂注入煤层后不断驱替CH₄,CH₄组分明显减少;气体吸附引起的煤层膨胀量可以抵消部分有效应力引起的压缩变形,由于CH₄-CO₂二元气体较单一CH₄引起的煤层吸附膨胀量大,二氧化碳注入煤层后可以缓解煤层的压缩变形;吸附膨胀引起的变形与孔隙压力变化引起的变形耦合作用对煤层孔隙压力和渗流率的变化具有重要影响但又与孔隙压力的分布密切相关。更多还原

【Abstract】 Complicated coupled binary gas-solid interaction arises during carbon dioxide sequestration in a coal seam,which combines effects of CO₂-CH₄ counter adsorption,CO₂-CH₄ counter diffusion,binary gas flow and coal bed deformation.Through solving a set of coupled field governing equations,a novel full coupled Finite Element （FE） model was established by COMSOL Multiphysics.The new FE model was applied to the quantification of coal porous pressure,coal permeability,gas composition fraction and coal displacement when CO₂ was injected in a CH₄ saturated coal bed.Numerical results demonstrate that CH₄ is swept by the injected CO₂ accompanied by coal volumetric deformation.Compared to the single CH₄ in situ, CH₄-CO₂ counter-diffusion induced coal swelling can make more compensation for coal shrinkage due to effective stress.Competing influences between the effective stress and the CH₄-CO₂ counter-diffusion induced volume change governs the evolution of porous pressure and permeability,which is controlled by the porous pressure correspondingly.This achievement extends our ability to understand the coupled multi-physics of the CO₂ geological sequestration and CO₂ enhanced coal bed methane recovery under field conditions.更多还原