Air-driven directional drilling technology and equipment in soft coal seam of Huainan mining area
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Abstract
Aiming at Huainan mining area using bedding directional drilling to eliminate gas outburst in strip coal seams of working face and adjacent roadways, we put forward a technical idea of using pneumatic long directional drilling hole to eliminate gas outburst by one hole. On the basis of the previous pneumatic screw directional drilling technology test, we developed a narrow-body full-section remote directional drilling rig with a width of only 1.1 m, the spindle angle can be stepless adjusted from −90° to 90°, and maximum remote distance of 50 m. The ø73/82 mm screw pneumatic screw drill was optimized, with maximum torque up to 256 N·m. A multi-functional dust collector is developed, which integrates the pressure air monitoring system and oil mist lubrication system. The electromagnetic wave while drilling system power battery was improved, then the system usage time and stability were improved. The technology of double dynamic composite strong slagging and directional drilling for long distance screen completion of crushed soft coal seam were developed. The test of soft gas dynamic directional drilling technology and equipment were carried out at 1682(1) transportion lane of Huainan Pansan Coal Mine. There were 16 drilling holes with depth of more than 240 m have been completed successively, with a total test footage of 4 548 m, and the penetration rate of coal seam reaches 93.1%. All directional holes run through the screen, with a maximum drilling depth of 423 m, which created the maximum drilling depth record of dynamic directional drilling for crushed soft coalbed methane in China. The continuous pumping has began during the test process, and the average extraction concentration is 60% and the maximum reaches 81%. The extraction mixture is basically maintained at 1.5 m3/min, the average extraction yield is 0.9 m3/min, the maximum extraction purity is 1.56 m3/min, and the total pure extraction was 174 000 square meters. The test results prove that the complete set of equipment is featured with stable performance, easy to use, remote control operation and safe construction, which meets the drilling needs of soft coal seam dynamic directional drilling. It has formed a set of soft coal seam directional drilling construction technology and equipment in Huainan mining area, providing necessary technology and equipment support for safe and efficient extraction in mining area.
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