Development path and key technology analysis of intelligent directional drilling in underground coal mine

Intelligent directional drilling is the advanced stage of underground drilling development in underground coal mine, which is a system engineering involving multi-disciplinary fields, has significant particularity and independence, and serves the whole process of intelligent mining.It provides a technical and equipment support for the safe, efficient, green and intelligent mining of coal resources.First of all, the development process of directional drilling technology and equipment in underground coal mine is described, from the stable bottom hole assembly directional drilling to the wireline measurement while drilling(MWD)and to the wireless MWD with high-power.The realization of the depth of in-seam directional borehole from "1 000 m" to "3 000 m" is promoted by the innovation and development of underground drilling technology and the replacement of drilling equipment.At present, the development orientation of underground drilling is still in the transition from mechanization to automation in underground coal mine in China.In this paper, the outstanding problems faced by intelligent directional drilling are analyzed, the development path of intelligent directional drilling based on the realization of automatic directional drilling is put forward, and the technical connotation and attribute characteristics of automatic and intelligent directional drilling are summarized and analyzed.The automatic directional drilling emphasizes the automatic control and execution of drilling actions, including the integrated control of automatic directional drilling rig, the information fusion of MWD with multi parameters, high-precision steerable control, and the automatic control of flushing fluid circulation, etc.The intelligent directional drilling emphasizes the intelligent optimization control, including intelligent analysis and decision, data transmission with low delay and large capacity, intelligent drill pipe, and the intelligent detection and diagnosis of drilling equipment, etc.In view of the occurrence conditions of complex and diverse coal seams and the mining technical conditions of unbalanced development, it is suggested to promote the exploration and development of intelligent directional drilling in underground coal mine by stages, regions and levels, and the key technical problems to be solved urgently are put forward, including the development of automatic directional drilling rig, the technology of rotary steerable drilling, the technology of geological steerable drilling, the 3D dynamic modeling technology of geological information with MWD, the establishment of intelligent drilling database, and the prevention and treatment technology of drilling accidents.Also, the phased development achievements of intelligent directional drilling in underground coal mine during the 13th five year plan are introduced. © 2020, Editorial Office of Journal of China Coal Society. All right reserved.