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

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.