Study on geochemistry discriminate method of gas emission in goaf

Abstract

In order to effectively distinguish the source of gas gush in the goaf of the coal mine, Sihe coal mine was chosen as the studied object. Carbon isotope of methane, ethane, carbon dioxide and hydrogen isotope of methane in gas from the desorbed gas of the working coal seam and the near coal seam, and gas in the goaf were tested, by systemic sampling coal samples and gas samples of the goaf. Combined with gas component from the goaf, the working coal seam and the near coal seam, the proportion of gas gush in the goaf were determined by the numerical calculation on separate source of isotopes. The results show that the difference of gas component, stable carbon and hydrogen isotopes of gas from the different coal seams is obvious. And the methane concentration in gas increase along with the increase of coal seam depth, carbon and hydrogen isotopes in gas become heavier along with the deepen of burial depth of coal seam depth. The results of the numerical calculation on separate source indicate that the proportion of the gushed gas in the lagged traverse No.1 from the desorbed gas of coal seam No.3∼No.8-2 is 38%, 37%, 12%, 8%, 5%, the proportion of the gushed gas in the lagged traverse No.2 from the desorbed gas of coal seam No.3∼No.8-2 is 22%, 36%, 24%, 12%, 6%.