Research on rotary geosteering drilling technology and equipment in underground coal mine

In view of the limitations of directional drilling technology and equipment for underground gas drainage in coal mining areas, such as low degree of automation, low drilling ratio of target formation, slow drilling rate of rock formation, and small diameter, the research of rotary geosteering drilling technology and equipment underground coal mine has been carried out, with the core technical problems has overcame such as wireless remote control operation of directional drilling rigs, mechanically automatic drill pipe addition, real-time parameter monitoring and fault diagnosis, coal and rock identification while drilling, and trajectory rotation control, ZDY25000LDK electro-hydraulic controlled directional drilling rig, BLY800/12 mud pump truck with high-pressure and large-volume, YSG(A) Mine geosteering MWD system by dynamic azimuth gamma, ϕ133 mm hydraulic push type rotary steering drilling system and supporting drilling tools have developed, with the maximum torque was 25 000 N·m, the automatically add drill pipe time was less than 55s of the directional drilling rig, the rated flow was 800 L/min of the mud pump truck, the natural gamma measurement error was less than ±5% and the stratum exploration distance was ≥0.5 m of the geosteering MWD system, the applicable speed range was 80−200 r/min and the deflection force was 1.4 t of the rotary steerable drilling system; geosteering drilling technology and rotary steerable drilling technology for near horizontal hole has developed with the technical characteristics and process flow are introduced in detail. The field test was carried out in Tangjiahui Coal Mine in Inner Mongolia. 4 directional drillings were completed, with the maximum drilling depth was 820 m, the total footage was 2 419 m, the directional drilling diameter was 172 mm, the drilling efficiency was increased 25% in coal seam and 30% in rock, which realized the directional drilling from “geometric steering” to “rotary geosteering” underground coal mine, the intelligent level and drilling trajectory quality of underground directional drilling in coal mine has been improved, and provided technical equipment support for efficient underground gas drainage and intelligent mine construction.