为了揭示不同宏观煤岩组分CH₄-煤吸附/解吸过程中煤体视电阻率的变化规律,以彬长矿区大佛寺煤矿侏罗系延安组4号煤层为研究对象,通过工业分析及不同煤样（暗煤、镜煤和原煤样）、含水率（空气干燥基样、自然吸水样和通风干燥箱温度为378.15 K的干燥样）视电阻率测试实验,分析了煤体视电阻率、甲烷吸附量和平衡压力之间的关系。研究发现,暗煤的固定碳含量高于镜煤,灰分、水分低于镜煤,暗煤干燥样（通风干燥箱温度为378.15 K）初始视电阻率最大。甲烷的吸附对煤体视电阻率的影响表现为随着甲烷吸附量增加,煤体视电阻率明显降低,升压（吸附）过程,煤体视电阻率与压力、吸附量呈二次函数关系,其主要原因是甲烷吸附放热、煤体膨胀以及水在孔喉内壁的铺展导致视电阻率降低。由于甲烷吸附导致煤基质表面发生气-水置换,游离水使得可溶矿物质溶解,离子浓度提高,煤体导电由电子导电变为离子导电为主辅以电子导电的混合导电,因此升压（吸附）过程,煤体视电阻率降低,但由于可溶矿物质的有限性以及煤的疏水性,使得吸附后期煤体视电阻率趋于稳定。降压（解吸）过程,由于煤基质膨胀后的收缩是不可逆（形变）,煤体视电阻率不能恢复到初始值。相较暗煤,镜煤孔隙连通性差,但孔喉曲率较大,此时双电层带电粒子数量多,成堆聚集,最终导致相同条件下镜煤的导电性能好于暗煤,即镜煤的煤体视电阻率小于暗煤的煤体视电阻率。

In order to reveal the change law of apparent resistivity in the process of CH₄-coal adsorption/desorption of different macroscopic coal petrology compositions, the No.4 coal seam of the Jurassic Yan'an Formation in Dafosi coal mine is taken as the experimental object. By the proximate analysis and apparent resistivity measurement experiments of different coal samples （the durain, vitrain and mixed samples） with different water content （air dry basis sample, natural water absorption sample and samples dried at 378.15 K） of coal, the relationship between the apparent resistivity, methane adsorption and pressures is studied. The experimental results found that when compared to the vitrain, the durain has higher fixed carbon content, but lower ash content and moisture. The initial resistivity of the samples dried at 378.15 K of the durain is the largest. The influence of the adsorption of methane on the resistivity of the coal body is manifested in that with the adsorption of methane, the apparent resistivity of coal is significantly reduced. During the pressure increasing process that is the process of adsorption, the coal resistivity has a quadratic function relationship with the pressure and the amount of adsorption. The reason is that methane adsorption heat release, coal body expansion, and the spread of water on the inner wall of the pore throat causes the apparent resistivity to decrease. Due to methane adsorption, gas-water replacement occurs on the surface of the coal matrix, free water dissolves soluble minerals, and the ion concentration increases. In the process of adsorption, the apparent resistivity of coal decreases, but due to the limited soluble minerals and the hydrophobicity of coal, the resistivity of coal tends to be stable in the later stage of adsorption. During the depressurization process, that is the process of desorption, since the shrinkage of the coal matrix after expansion is irreversible （deformation）, the apparent resistivity of the coal body cannot be restored to its initial value. Compared to the durain, the pore connectivity of vitrain is poor, but the pore throat curvature is larger, when the number of charged particles in the double electric layer is high and aggregated in piles. This eventually leads to better electrical conductivity of vitrain than durain under the same conditions, i.e., the apparent resistivity of vitrain is smaller than that of durain.