Roof high directional long borehole is an effective technical means for mining relief gas treatment, which has been popularized and applied in Huainan, Huaibei, Jincheng and other coal mine areas. However, there are several problems in the trial in Binchang Mining area: the efficiency of the formation breaking into holes in the hole section of coal-rock penetration is low, and there are many accidents in holes such as stuck and broken drilling. The diameter of a reaming hole is generally within 153mm, and the hole diameter is small, so the gas extraction effect needs to be improved. After opening the hole, the gas extraction channel is easy to be blocked, and the effective utilization period of drilling is short.
Aiming at the technical problems existing in the construction of the high directional length hole in the roof, the technology of large-diameter casing hole protection in the broken hole section through the layer, the double-stage and double-speed one-time large-diameter hole reaming process and the method of steel screen hole completion are developed, and the "driller, expander-completion" integration technology with the diameter of 200mm complex high large-diameter directional hole in the roof is studied.
A demonstration application was carried out in a mine in Changwu, Shaanxi province. With the integration technology of drilling, enlarging and finishing with the diameter of high directional hole with 200mm complex roof, it successfully solved the technical problems encountered by the mine in the construction of high directional hole with roof, such as low porosity of broken hole section through layer, small diameter of single reaming hole and easy blockage of open hole completion gas extraction channel. At present, the construction task of one demonstration hole has been successfully completed, with a hole depth of 511m and a diameter of 200mm, with a diameter of 89mm steel screen pipe inserted into the whole hole, meeting the technical requirements of the high directional long drilling of the roof of the mine construction. The successful application of this technology expands the application range of high directional long hole in roof, and contributes to better promoting the development of "using hole to replace roadway" technology.
