煤层注水对原煤孔隙及甲烷吸脱附性能的影响

煤层注水对防突具有显著效果,而煤层孔隙特性是影响瓦斯吸脱附及渗流的重要因素,为了从孔隙角度揭示不同注水压力对原煤体甲烷吸脱附性能的影响。选取首山矿己15-12070工作面进行煤层注水现场实验,使用氮吸附法得出各煤样孔隙特性并用分形理论计算孔隙粗糙度,使用静态容量法测出各煤样吸脱附参数。结果表明:注水后各孔径段孔隙量均有所增加,注水压力与比表面积、孔容及分形维数呈线性正相关关系;孔隙特征参数与甲烷吸脱附性能呈线性正相关关系;各煤样均出现甲烷吸脱附迟滞现象,且注水压力越高,甲烷吸附能力越强,脱附迟滞程度越大。煤层注水压力越大,煤的孔裂隙数量会增多且粗糙度增大,煤体倾向于保留更多的瓦斯。

Influence of coal water injection on pore and methane adsorption/desorption properties of raw coal

Coal seam water injection has a remarkable effect on outburst prevention.Pore characteristic of coal seam is an important factor affecting gas adsorption/desorption and seepage.In order to research the influence of coal seam water injection on methane adsorption/desorption characteristics from the pore point of view,the ji 15 12070 face in Shoushan mine was selected for coal seam water injection experiment.The nitrogen adsorption method was used to study the pore characteristics of each coal sample and the fractal theory was used to calculate pore roughness.Then the static volumetric method was used to measure the adsorption/desorption parameters.The results show that the pore volume of each pore section increases after water injection,and the injection pressure has a positive correlation with specific surface area,pore volume and fractal dimension.Methane absorption/desorption hysteresis appears in each coal sample,and the higher the injection pressure is,the stronger the methane adsorption capacity is,and the greater the desorption hysteresis is.The number of pores and the roughness will increase with the increase of coal seam water injection pressure,it tends to retain more gas.