Gas Drainage by High Position Directional Long Borehole in Close Distance Coal Seam Group

In order to effectively solve the problem of gas over limit in the upper corner of coal mining in 21602 working face in Qinglong Coal Mine, with the advantage of controllable trajectory and wide coverage area of directional drilling technology, the high directional long borehole was arranged in 21602 working face to extract the pressure relief gas. This paper introduced the technical principle of gas extraction by high directional long borehole, analyzed the layout and design scheme of the borehole. Through field practice, it was determined that the long directional borehole should be arranged preferentially in the range of 16 m to 28 m from roof to coal seam in 21602 working face. The drainage effect shows that the gas concentration in the upper corner of 21602 working face is reduced to the range from 0.20% to 0.40%, which is up to 0.72% before the extraction, the single-hole gas extraction is 1.58 m³/min. It effectively guarantees the efficient and safe mining of the working face, and provides experience for the gas control in the upper corner of close distance coal seam group.