Analysis of abnormal gas in gas weathered zone of Ningdong mining area

During mining in gas weathered zone, the gas is not a major threat to production. But in this research, the high concentration of methane gas is found from the geological inspection drilling in the gas weathered zone for colliery construction. Through regional geological analysis and the geology exploration, it is found that in the initial district in arched structure zone, there is free gas accumulation in sandstone in roof due to the influence of geological structure. Through targeted gas drainage by boreholes, nearly 200 million m³ of pure gas were drained during 3 months. The study results indicated that there may exist an area with high gas concentration in gas weathered zone with closure conditions.