Progress of drilling technologies and equipments for complicated geological conditions in underground coal mines in China

According to the drilling technology requirements and problems under complicated geological conditions, such as broken soft coal seam, hard rock, rockburst strata, fractured zone, water-sensitive strata, etc, the research and application of drilling technology and screen pipe protection in broken soft coal seam, comb-like directional drilling technology in broken soft coal seam, high-level directional drilling technology in complicated roof strata, full-section across-layer drilling technology of hard rock, and drilling technology for pressure relief in rockburst strata were summed. This paper puts forward the research approaches of the technology and equipment of double-pipes directional drilling and rotary directional drilling in broken soft coal seam, which are helpful to improve the drilling depth, the diameter of the screen and the drilling efficiency, and the improvement of directional drilling technology and support equipment will also promote the change of gas extraction mode of broken soft coal seam. The research of drilling robots for gas outburst prevention and coal bump prevention are the development trend of drilling technology and equipment under complicated geological conditions in underground coal mines, which can promote the construction of unmanned coal mines. In addition, the influence of local complex strata on drilling should be solved to better promote the progress of intelligent drilling technology and equipment, so as to ensure the safe and efficient production of coal mines.