Genetic type of abnormal gas emission from coal seam floor in Huangling mining area

Coal and oil-gas exist in Huangling mining area together, abnormal gas emission from coal seam floor has occurred in multiple working faces. In order to ascertain the genetic type of abnormal gas emission, 44 gas samples were collected from seam floor and 12 samples from NO.2 coal seam, test of geochemical parameters for carbon isotope of methane and hydrogen isotope was conducted. Test and analysis result shows that the abnormal gas is not derived from NO.2 coal seam, the value of carbon isotope of methane(δ¹³C₁) is 52.20‰~42.80‰, and the value of carbon isotope of ethane (δ¹³C₂) is 37.20‰~29.01‰, the genetic type of abnormal gas emission from coal seam floor belongs to the oil-type gas. By analyzing the distribution of source rocks and the fracture system, it is suggested that abnormal gas emission comes from the sourcerock of Yanchang Formation.