Application of pneumatic directional and efficient pore-forming technology for crushed soft coalbed methane in Wangpo Coal Mine

According to the demand of regional gas control in Wangpo Coal Mine crushed soft coal seam area, the pneumatic directional drilling technology was introduced to optimize the existing pneumatic directional drilling process and equipment. Through upgrading the pneumatic screw drilling tool, the rated torque was increased to more than 450 N·m. The 89 mm spiral cable drilling pipe with low wind resistance was developed to realize the construction hole depth of the connected cable measuring system of pneumatic directional drilling to more than 300 m. Based on the tecnique of the “wave type” accurate detection of coal seam top and bottom trajectory, from the principle of directional drilling and branching, the technology of rapid branching is realized by improving the strength of drilling tool. We systematically analyzed pneumatic directional drilling in different strata trajectory variation characteristics, summed up the precise trajectory control technology, and the pneumatic directional drilling process construction efficiency is greatly improved. During the field test, a total of 34 main holes and 49 branch holes were constructed, with a total footage of 17 287 m, an average hole depth of 305 m, an average daily footage of 103 m/d and a maximum of 154 m/d. The average extraction concentration of the borehole was above 60%, and the pure extraction volume of the 100-meter borehole was 2.7 times that of the ordinary borehole in the adjacent area.