基于热力学方法的煤岩吸附变形模型

摘要

基于吸附过程的热动力学和能量守恒原理,建立了计算煤岩吸附气体引起的煤岩膨胀应变的理论模型,在获取煤岩对气体的吸附等温曲线的基础上,可通过模型得到煤岩吸附气体引起的吸附应变;利用已有的实验数据对模型的有效性进行了验证.结果表明,实验结果与模型预测的结果吻合较好,模型能够很好地描述煤岩吸附不同气体时产生的差异性膨胀现象;另外,模型可为预测CO2注入煤层后煤基质收缩/膨胀效应对储层渗透率的影响提供指导.%Based on the thermodynamics of adsorption and principal of energy balance, a theoretical model was developed to describe gas adsorption-induced coal deformation.This model was used to calculate the adsorption induced strain of coal through the gas adsorption isotherm,some experiment datas were used to validate the model.The results suggest that the model agrees well with experimental data of coal deformation induced by the gas adsorption, the model can describe the differential swelling phenomenon of coal caused by adsorption of different gas such as carbon dioxide,methane and nitrogen.Furthermore,this model provides a sound basis for estimating the dynamic change of coalbed permeability in response to swelling/shrinkage of coal matrix and can be applied to CO2-enhanced coalbed methane recovery and CO2 sequestration in deep,unminable coalbeds.