TORSIONAL PENDULUM DRAG REDUCTION TECHNOLOGY FOR DIRECTIONAL DRILLING OF ULTRA DEEP HOLE IN UNDERGROUND COAL MINE

Aiming at the problems such as low efficiency and depth limit of directional drilling caused by the support pressure of drilling tools in the directional drilling of ultra-deep hole in underground coal mine, learning from the twist drilling technology in oil drilling, this paper analyzes the technological dea eyewear principle, the adaptability and

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