Key techniques for directional drilling & construction for control of coal floorOrdovician limestone karst water disaster

Based on the directional drilling project for the prevention and control of ordorician limestone karst water disaster in a mine of Weibei, the key technology of hole forming was studied. The results show that the deep hole exploration can be realized in the 46 m layer below the coal seam floor; the method of air drilling can successfully solve the problem of poor slag discharge and difficulty of hole formation. Drilling tools can ensure the casing pipe travels down to the design depth; deep-hole casing can be realized by using a rotary drill process by using a pilot drill; The internal high-pressure grouting and the annulus static pressure filling can ensure the sealing quality of the casting; the combination of slide directional drilling and rotary drilling can greatly improve the drilling efficiency; the branch hole can be successfully drilled in the section of increasing inclination angle with a drilling pressure of less than 0.5 MPa; different drilling methods are used to judge the properties of water-bearing geological anomalies; the rotary drilling method can be used for a fast and multi-passing through holes, or taking directional drilling of large angles to pass through the collapsible section. The research results provide technical support and theoretical basis for the prevention and control of the ordorician limestone karst water disaster in the Weibei coal field.