Optimization and Application of High-level Directional Borehole Technology in Tangkou Coal Mine

Based on the theory of goaf roof vertical “three zones” and “O” shape circle theory, and combined with the actual situation of Tangkou Coal Mine, the parameters of designed trajectory for high-level directional borehole in Tangkou Coal Mine are identified. Aiming at the drilling situation of opening coal seam and mudstone section, the high-level directional drilling process is optimized, and the scheme of putting the casing down into the roof and using the helical directional drill pipe for the mudstone section is proposed. By optimizing the design of the high-level directional drilling process, it is possible to ensure that the high-level directional drilling hole smoothly climbs to the designed height in the mudstone section and improves the gas extraction effect. The later gas extraction data show that the high drilling parameters are reasonable, and the optimized high-level directional drilling process has fully exploited the advantages of low cost drilling and low cost. For the existing situation, the paper proposes the influence of the diameter of the end hole on the extraction efficiency.