煤吸附解吸甲烷细观结构变形试验研究

利用扫描电镜与CT扫描相结合的方法,通过对直径为8.5 mm的细观煤样进行不同压力下的吸附解吸甲烷试验,研究其内部细观结构的变形规律。研究表明,煤样是煤基质中含有少量黏土矿物质的天然非均质岩体;吸附解吸甲烷过程中,煤的细观结构变形分为膨胀变形(密度减小)与挤压变形(密度增大)。低吸附压力下,含黏土矿物质区域急剧膨胀,对邻近煤基质形成局部挤压,细观变形程度明显,压力升高后膨胀变形增强,挤压变形减弱;不含黏土矿物质的煤基质区域变形程度较低,近似于均匀变形。解吸后,煤不同区域的变形恢复能力与其非均匀程度有关,非均匀性越强,其变形恢复能力越差。

Experiment on the deformation of the meso-structure of coal during the methane adsorption and desorption

The changes of microstructure of coal sample with a diameter of 8.5 mm are observed by SEM and CT scanning during methane adsorption and desorption under different pressures.The study shows that coal is a kind of natural non-homogeneous rock consisting of coal matrix and a small amount of clay minerals.In the process of methane adsorption and desorption，the structure deformation of coal can be divided into expansion deformation (density decrease) and extrusion deformation (density increase).Under a low adsorption pressure，the regions containing clay minerals expend rapidly，which has a strong extrusion effect on the adjacent matrix of coal，and leads to significant deformation.With pressure increase，expansion deformation is enhanced and extrusion deformation is weakened.The coal matrix regions without clay mineral have a low degree of deformation，which can be approximated to homogeneous deformation.After desorption，the recovery abilities of different coal regions are related to the degree of non-uniform.The stronger the non-homogeneity，the worse the ability of deformation recovery.