贵州盘县某矿区孔裂隙发育及煤变质程度对煤储层渗透性影响初探

Discussion on how the pore fissure development and coal metamorphic degree affected the coal reservoir permeability in a mining area in Pan County Guizhou Province

基于煤储层渗透性是煤层气资源开发成败的关键因素,结合贵州盘县某矿区的煤层裂隙发育程度,从研究区的部分煤层孔隙率、多组煤样的液氮吸附和压汞实验、煤样矩形网状裂隙发育形态、孔隙发育状况及煤岩裂隙形态等方面剖析了孔裂隙发育程度对研究区煤储层渗透性的影响。煤变质程度对贵州矿区煤储层渗透性影响研究表明:渗透率和孔隙度总体趋势随着镜质组最大反射率逐渐升高,有先减小后增大的明显趋势;煤阶较低煤层的煤岩孔隙度大,渗透率较高;随着埋深的逐渐增加,煤变质程度逐渐加大,其渗透率随之降低;但镜质组最大反射率大于2.5%时,煤层孔隙度和渗透率也随之变大。

Based on that the coal reservoir permeability is the important factor to discuss whether a coal bed gas can be successful, combining with coal seam pore fissure development of mining area in Pan County of Guizhou, and from aspects such as partial coal seam porosity of research area, liquid nitrogen adsorption of multiple groups of coal samples and mercury injection experiment, morphology of rectangular mesh fracture of coal sample, pore development and coal petrography fracture morphology, how the pore fissure development degree affects the coal reservoir permeability rate was discussed. The effect of coal metamorphic degree on the coal reservoir permeability in Guizhou mining area showed that： along with the increase of vitrinite maximum reflectivity, the permeability and porosity reduced firstly and then increased obviously; coal petrography porosity of tow rank coal seam was large, the permeability was high; with the increase of depth, the coal metamorphic degree would increase gradually, the permeability reduced; when the vitrinite maximum reflectivity was more than 2. 5 %, the coal seam porosity increased gradually, the permeability increased as well.