Present situation and prospect of directional drilling technology and equipmentwhile drilling measurement in underground coal mine

Near-horizontal directional drilling in coal mine can realize advanced, regional and accurate disaster prevention and gas extraction and utilization, and plays an important role in coal mine geological guarantee. This paper systematically introduces the development course and application status of directional drilling technology with measurement while drilling in underground coal mines at home and abroad.For drilling rigs, mud pump vehicles, explosion-proof while drilling measurement systems in domestic directional drilling equipment, supporting drilling tools, including central cable drill pipes, screw motors and drill bits,the key technologies and equipment, including sliding directional drilling and compound directional drilling, and sleeve milling and salvage technology, are briefly analyzed and summarized. The functional characteristics and applicability of wired while drilling measurement system, mud pulse wireless while drilling measurement system, electromagnetic wave wireless while drilling measurement system and geological guidance while drilling measurement system in small volume explosion-proof while drilling measurement system are described.In order to improve directional drilling hole formation rate, ultra-deep hole drilling construction ability and formation adaptability in complex roof,the paper introduces the typical field application cases of ultra-deep directional drilling and high directional drilling of complex roof in Baode Mine, Longwanggou Mine and Guqiao Mine. Based on development status and field application of complete set of technology and equipment, the development direction and trend of directional drilling technology and equipment with measurement while drilling in underground coal mine are prospected. The automation, information and intelligence of the equipment will become the direction of technical research and key requirements of the field.The rotary guided drilling system and large diameter directional drilling system with high efficiency and fast drilling will be verified by the field practice.