Reservoir Properties Influence on Gas Emission of 14211 Prepared Mining-Face, in Seam II 1 of Xin’an Coalmine, Henan Province

Abstract

Abstract 14211 was a prepared mining-face in Xin’ an Coalmine, Henan province, and it has not been done any work for mining so far. Geological parameters selected in this paper include seam thickness, burial depth, sandstone ratios in 20m and 40m coal seam roof, gas content and minor faults. With the calculating results of gas emission from 2007 to 2010 in other working faces, this paper interpreted the influence on gas emission of selected geological parameters. The gas emission was combined with characters of micro-cracks, permeability and isothermal adsorption. The results demonstrated that, in 14211 preparing face, there is a negative correlation between the absolute gas emission and 20m-sandstone ratio, while a significant positive correlation between the absolute gas emission and the 40m- sandstone ratio. There is gas conductivity in 20m-sandstone, adjacent to the coal seam roof. And this effect becomes so less indistinguishable in sandstone far away from coal seam that it transforms to the gas-storage effect, which is the same with tight sand and mud stone. Analysis concluded that this phenomenon is intimately associated with macroscopic type of coal and characteristic of micro-crack, isothermal adsorption and permeability.