Understanding the desorption and seepage behaviors of CO₂ gas and CO₂–CH₄ gas mixture in coal is important for CO₂ geological sequestration and enhanced coalbed methane recovery. An experimental study of desorption and seepage in coal under the action of a single gas (CO₂) and a gas mixture (50% CH₄, 50% CO₂) was conducted under the influence of the pore pressure and stress environment. The results indicated that the CO₂ permeability of coal increased with increasing pore pressure and decreased with increasing σ₁ and σ₃. CO₂ desorption increased with increasing pore pressure, and the Dubinin–Astakhov model suitably captured the CO₂ desorption behavior. Under the same hydrostatic and pore pressure conditions, the seepage volume of CO₂ was significantly larger than the desorption volume. Regarding the considered CO₂–CH₄ gas mixture, the seepage volume decreased exponentially as a function of time and the desorption volume increased exponentially over time. Regardless of seepage or desorption in the tests, the CH₄ concentration in the CO₂–CH₄ gas mixture at the outlet was always higher than that of CO₂, which is closely related to the gas pressure, microscopic composition of coal, and coal rank. An increase in coal rank could increase vitrinite reflectance, due to the higher affinity of CH₄ for vitrinite, and due to the relatively low solubility of CO₂ under low pressures, preferential CH₄ desorption occurred. As the test proceeded, the concentration of desorbed or seeped CH₄ decreased gradually, the concentration of CO₂ continued to increase, and finally, the relative concentrations of these two gases equalized eventually.

了解CO ₂ 气体和CO ₂ -CH ₄气体混合物在煤中的解吸和渗流行为对于CO ₂ 地质封存和提高煤层气采收率具有重要意义。在孔隙压力和应力环境的影响下，进行了单一气体（CO ₂）和混合气体（50% CH ₄、50% CO _{2 ）作用下煤的解吸和渗流实验研究。}结果表明，煤的CO ₂ 渗透率随着孔隙压力的增加而增加，随着 σ ₁ 和 σ ₃的增加而降低。二氧化碳₂ 解吸随着孔隙压力的增加而增加，并且 Dubinin-Astakhov 模型适当地捕获了 CO ₂ 解吸行为。在相同静水压力和孔隙压力条件下，CO ₂的渗出量 明显大于解吸量。对于所考虑的CO ₂ -CH ₄气体混合物，渗流体积随时间呈指数下降，而解吸体积随时间呈指数增加。试验中无论渗漏还是解吸，出口处CO ₂ -CH _{4混合气中CH 4} 浓度始终高于CO _{2 。}，这与瓦斯压力、煤的微观组成和煤阶密切相关。_{由于CH 4} 对镜质体的亲和力更高，并且由于CO ₂ 在低压下溶解度相对较低，因此煤阶的增加可以增加镜质体的反射率，从而发生优先的CH ₄解吸。随着试验的进行，解吸或渗出的CH ₄浓度逐渐降低，CO ₂浓度 继续升高，最终这两种气体的相对浓度最终趋于平衡。