Large aperture milling and salvage techonlogy and technic parameters ofdirectional deep-hole in underground coal mine

In order to solve problem of directional deep hole stuck drilling in coal mine, the directional deep-hole large aperture milling and salvage technology is adopted. Through analysis and calculation of depth of hole where accident occurs, analysis of passing capacity of milling and drilling tool in curved hole, and study of process parameters of milling and drilling, the research could solved the directional drilling stuck accident when the hole depth exceeds 700 m. The application results show that large aperture milling and drilling tools have a strong ability to penetrate bending holes, which can effectively improve success rate of dealing with targeted deep-hole stuck accidents; high spinning speed and high drilling speed will not only cause increase of swing pressure, but also cause sleeve milling tool to break, and high speed will increase wear of accident drilling tool, and high drilling speed will easily cause drills to be stuck by sediment; it is recommended that drilling speed is controlled at 4～25 m/h and the spinning speed is controlled at 10～80 r/min.