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基于三轴应力条件下,煤岩有效应力、吸附膨胀量和渗透率的一体测试,研究了晋城无烟煤吸附甲烷和二氧化碳后,渗透性随有效应力改变和煤岩吸附膨胀效应的变化规律.认为煤岩吸附膨胀量和孔隙压力的关系可用兰氏方程描述;煤岩渗透性同有效应力、吸附膨胀量均呈负指数函数关系,同时结果表明:甲烷和二氧化碳在晋城无烟煤中的扩散方式不同,煤岩对甲烷的吸附膨胀符合单孔气体扩散模型,而对二氧化碳的吸附膨胀符合双孔气体扩散模型,且甲烷的吸附膨胀速率小于二氧化碳的吸附膨胀速率;煤岩饱和吸附后,各孔隙压力条件下的初始渗透率与孔隙压力呈幂函数关系减小.针对晋城无烟煤,同等条件下煤岩吸附甲烷后的渗透率为吸附二氧化碳后渗透率的1.14～1.51倍,大部分在1.30倍左右.
Based on the three-axis stress test, an effective test of coal-rock effective stress, adsorption and expansion, and permeability was carried out to study the variation of permeability with the change of effective stress and the adsorption and expansion of coal and rock after the adsorption of methane and carbon dioxide into Jincheng anthracite. The relationship between the amount of rock adsorption and pore pressure and pore pressure can be described by Rankine’s equation. The permeability of coal rock shows a negative exponential function with the effective stress and the amount of adsorption and expansion. The results show that the diffusion modes of methane and carbon dioxide in Jincheng anthracite are different, The adsorption and expansion of methane on rocks are in accordance with the single-hole gas diffusion model, while the adsorption and expansion of carbon dioxide accords with the two-hole gas diffusion model, and the adsorption and expansion rate of methane is less than that of carbon dioxide. The initial permeability decreases with the pore pressure in a power function relationship.According to the Jincheng anthracite, under the same conditions, the permeability of coal after methane adsorption is 1.14 ~ 1.51 times of the permeability after carbon dioxide adsorption, most of which is about 1.30 times.