为了研究煤层渗透率在煤层注入CO₂以驱替CH₄（CO₂-ECBM）过程中的时空演化规律，以离柳矿区地质条件为工程背景，采用COMSOL Multiphysics数值模拟手段，建立了CO₂-ECBM流-固-热多场耦合数值模型，采用五点布井法对CO₂-ECBM过程进行了数值模拟，对煤层渗透率随CO₂注入的时空演化规律进行了讨论。研究表明：瓦斯压力、CO₂注入以及煤基质的收缩/膨胀变形是影响渗透率演化的关键因素；煤基质吸附CO₂之后，其膨胀变形起主导作用，占据孔隙空间，导致渗透率下降，CO₂影响范围内的渗透率平均值降低了40%；沿CO₂注入井至抽采井，渗透率受CO₂影响越来越小，呈单调上升趋势；CO₂影响范围外，渗透率平均值增加14%。

In order to study the spatio-temporal evolution law of coal seam permeability in the process of CO₂-ECBM, a CO₂-ECBM fluid-solid-thermal multi-field coupling numerical model is established by using COMSOL Multiphysics numerical simulation method based on the geological conditions of Liliu Mining Area as the engineering background. The CO₂-ECBM process is numerically simulated by five-point well layout method, and the spatio-temporal evolution of coal permeability with CO₂ injection is discussed. The results show that gas pressure, CO₂ injection and shrinkage/expansion deformation of coal matrix are the key factors affecting permeability evolution. After the adsorption of CO₂, the expansion deformation of coal matrix plays a leading role, occupying the pore space, resulting in the decrease of permeability, the mean permeability in the range affected by CO₂ decreased by 40%. Along the CO₂ injection well to the extraction well, the permeability is less and less affected by CO₂, it shows a monotonic upward trend. The mean permeability increased by 14% outside the influence range of CO₂.