Research and application progress of key technologies of drilling method for deep and thick water-bearing weakly cemented bedrock in western China

The drilling method has been successfully applied in the shaft construction of deep water-bearing weak cemented bedrock in the west, which shows the development direction of less people, safety, green and intelligent well construction technology. In order to solve the engineering problems of shaft construction by this method, the drilling method sinking technology is continuously iteratively developed. The key technical problems are analyzed from many aspects, such as drilling rig, cutter cutterhead, rock breaking drilling, shaft wall structure and construction technology. The recent domestic research and application progress are introduced, and the key research direction in the future is put forward. Key technical problems: China’s existing shaft drilling rigs are difficult to meet the characteristics of the strata in western China and the construction requirements of deep and large shafts. It is urgent to develop a new generation of large shaft drilling rigs with large drilling torque, sufficient power and high automation level. When crossing the Jurassic argillaceous sandstone in the west, the effect of slag discharge is poor, the tool wear is serious, the drilling efficiency is low, and it is easy to make slurry. Borehole wall structure and design calculation method suitable for western formation characteristics; stability calculation of floating and sinking process of deep and large shaft wall. Research progress of key technologies: ZMD120/1200 new drilling rig suitable for shaft construction in deep water-bearing bedrock in western China was developed. Taking rock breaking specific energy and rock drillability as characteristic parameter classification indexes, the classification standard of Jurassic rock drillability is proposed. The distribution law and main influencing factors of slag discharge flow field are clarified, and the evaluation index and method of optimizing the structure form of bit slag suction port are put forward, and the mechanical mechanism of rock breaking by milling cutter is revealed. Developed a new type of low solid mud and control technology; a new type of high-strength drilling wellbore structure adapted to the conditions of the western region is proposed, and the corresponding design and calculation methods are improved. The large specific gravity backfill material was prepared, and the floating sinking and backfill technology of deep and large wellbore was developed. The key research directions in the future are as follows: optimization and upgrading of drilling rigs and intelligent monitoring, global optimization of high-efficiency drilling of cutterhead and cutter-ballast discharge parameters, drilling method and shaft sinking technology in western Permo-Carboniferous strata, drilling method and shaft sinking technology system and related standards and specifications in western China.