Safe Drilling Technique for Boreholes with Both Gas and Water Inrush in Coal Mine

The mining of coal formation A in the Permian system in Huainan Coal Mining Area is faced with the threat of high pressure limestone water in the floor strata, the high pressure water and gas inrush in the drilling process seriously threatens the safety of mine production. For this purpose, a new gas drainage device against high pressure water and gas inrush was designed, its principle, structure and operation method were described, and the drilling process and protection measures were expounded. The site application results showed that the use of this device and its supporting drilling technique could realize the safe mining of coal formation under the control of high pressure water and gas inrush.