Study on hole-forming technology of high-level directional borehole in complicated roof strata

The large diameter high-level directional borehole in the roof is the key technical measures for gas drainage and control of the goaf. Aiming at the difficulty of large-diameter high-level directional borehole in the complicated roof strata in Huainan mining area, the technical research of borehole in the complicated roof was carried out combining with industrial test in Guqiao mine of Huainan mining area, and the key technologies of borehole was formed, such as the detection technology of detailed information of complicated roof strata, directional drilling of climbing borehole interval and the complicated interval of target layer, the technology of borehole completion etc, and 10 large-diameter(Ф153 mm) high-level directional boreholes in the roof were drilled successfully. In the stage of drainage test, the average gas flow of the test borehole under standard conditions reached 11.07 m³/min with an average concentration of 31.39%, equivalent to the level of gas drainage of the adjacent gas drainage roadway, and the goal of "replacing the roadway with boreholes" was preliminarily realized. The results provide a new approach for gas control in Huainan mining area and mining areas with similar geological conditions, which has significant application value and promotion value.