Deep Hole Directional Drilling Technology for Regional Gas Drainage in Xishan Coalfield

Geological characteristics of Xishan Calfield and theory of gas drainage were analyzed systematically. Based on deep hole directional drilling technolog y, methods for holes drilling along seam and high-roof fractured zone of regional gas drainage were proposed and applied in Xishan Coalfield, and drilling parameters d esign of five high gassy mines in Xishan Coalfield were adopted. By using holes drilling along Seam of regional gas drainage in three mines, the gas drainage mean val ue was about 1. 0 m3/ min to 1. 5 m3/ min, and gas remainder quantity was less than 7 m3/ t within the required pre-drainage time, using high-roof fractured zone of re gional gas drainage in2 mines, the average concentration of gas drainage of high-roof holes were about 30% to 50%, and the gas concentration of return airway were le ss than critical value 0. 5%, as the impelling quantity of working face was more than the limit of caving span.