Application of Medium Air Pressure Drilling Technology in Construction of Mining-coal Bed Gas Discharging Boreholes

Aiming at low air pressure and limited drilling depth of air drilling method of gas discharging boreholes in current outburst coal seam, based on basic principle and technological process of air drilling method, combining with field experiments of gas discharging boreholes using medium air pressure drilling technology in actual outburst coal seam, medium air pressure drilling system and drilling tools for outburst coal seam were deployed, and then medium air pressure drilling technology and technology process was proposed. The field experiments results show that medium air pressure drilling technology and process can effectively reduce construction time, increase borehole area and improve success rate and drilling depth of gas discharging boreholes, which provides a new approach to solve deep borehole drilling of mining-coal bed and coal seam gas treatment; besides, existing problems and its solutions of actual application of medium air pressure drilling technology were also indicated.