Directional drilling technology and equipment for efficient and accurate gas drainage underground coal mine

Underground directional drilling can realize advanced, regional and precise gas drainage, which is an important technical means for coalbed methane (gas) development in coal mining area. In view of the needs for full-scale, efficient and precise gas drainage underground coal mine, and with the support of the major national science and technology projects in the 13th five year plan, three kinds of major equipment had been developed, such as underground rotary geosteering intelligent directional drilling technology and equipment, double power head and double pipe directional drilling technology and equipment for soft-fragmentized seam, underground large-diameter high-level long borehole directional drilling technology and equipment, which were suitable for different types gas drainage directional drilling construction in different coal bearing strata. The automatically add drill pipe time was less than 55 s of the underground rotary geosteering intelligent directional drilling technology and equipment, with the accuracy rate of typical fault diagnosis was 90%, the stratum exploration distance was ≥0.5 m, the deflection force of rotary guidance system reached 1.4 T, and the maximum drilling depth was 820 m, which improved the intelligent level of directional drilling equipment and realized the directional drilling from “geometric steering” to “rotary geosteering” underground coal mine. The rated torque of casing power head was 6000 Nm of the double power head and double pipe directional drilling technology and equipment for soft-fragmentized seam, with the rated torque of drill pipe power head was 3000 Nm, and the diameter of sieve pipe was Ф75 mm, the borehole forming rate in soft-fragmentized seam with the depth of more than 250 m reached 75%, which made the applicable stratum range of directional drilling from f ≥ 0.8 to f ≥ 0.3 and realized the progressive gas drainage. The rated torque was 23000 Nm of underground large-diameter high-level long borehole directional drilling technology and equipment, with the diameter of one-time borehole forming was 153 mm, the diameter of one-time reaming was 300 mm, and the maximum drilling depth was 1071 m, which improved the borehole forming diameter of high-level directional drilling and provided technical equipment support for “hole instead of roadway” for mining gas drainage. These technical equipment had significantly improved the borehole forming capacity and gas extraction effect of underground gas extraction directional drilling, promoted the progress of underground gas extraction technology, and ensured the safe, efficient and green mining of coal mine. © 2023 Coal Science and Technology. All rights reserved.