合阳矿区煤体孔隙结构对瓦斯吸附-渗流特性影响的实验研究

Experimental Study on Influece of Coal Pore Structure on Gas Adsorption and Seepage Characteristics in Heyang Mining Area

为了研究合阳矿区煤体的孔隙结构对瓦斯吸附-渗流特性的影响,采用低温液氮吸附实验、压汞实验及扫描电镜实验相结合的方法测试了该矿区原生结构煤和软分层煤全孔径孔隙结构特征。结果表明:低温液氮吸附实验得出软分层煤样比原生结构煤样脱附曲线的拐点更加明显,软分层煤样含有更多的狭缝平板孔和墨水瓶孔孔隙。压汞实验测得软分层煤样总孔容是原生结构煤样总孔容的2倍多,应力破坏作用使得软分层煤样中孔、小孔及微孔孔容增大,而大孔孔容减小。扫描电镜实验显示软分层煤的储层物性发生了改变、惰质组破裂产生角砾且孔隙表面有多个气孔密集发育。通过分析得出,合阳矿区煤体孔隙结构中多以微孔和小孔为主,利于煤层瓦斯吸附而不利于渗流扩散。

In order to study the influence of pore structure on gas adsorption and seepage characteristics in Heyang Mining Area,this paper adopts the low-temperature liquid nitrogen adsorption, mercury injection and scanning electron microscope to investigate the full aperture of coal pore structure characteristics with the initial and soft coal samples in this mining area. The result indicates that the point of inflection around the isothermal adsorption curve of soft coal sample is more obvious than the raw coal sample, which revels that the soft coal sample contains more slit flat holes and ink bottle pore structures. The total pore volume of soft coal sample is 2 times than that of initial coal sample by using mercury intrusion method, furthermore, the stress failure makes the accumulative valume of micro-pores, transition pores and mecro-pores of soft stratified coal sample increase while the valume of large pore decreases. Scanning electron microscopy shows that the reservoir property of soft stratified coal has changed, the inertial formation breaks down to form keratites and a number of air holes densely developed on porous surface. Through analysis,it is concluded that the pore structure of the coal body in Heyang Mining Area is mainly composed of micropores and transition pores, which is beneficial to the gas adsorption of the coal seam and not conducive to the seepage diffusion.