Downward directional drilling and hole protection technology for coal roadways strip outburst prevention in soft thin coal seams
In view of the problems of difficult hole formation,easy to drill into the coal seam roof and floor,and water blocking the gas extraction channel,the technology of downward oblique directional drilling and hole protection was proposed,using high-pressure nitrogen slag discharge,high-power pneumatic screw drilling tool orientation,"wave-type"trajectory control and three-layer pipe hole protection and drainage technology,which was tested in Pingmei No.1 Mine,and 8 holes with a depth of more than 300 m were completed,and the coal seam drilling rate was more than 90%.The average depth of the three layers of drainage pipes in the whole hole section was 302 m,the average pure pumping volume of the branch pipe was 1.66 m3/min,and the average gas concentration was 17.5%.The test results show that this technology can effectively solve the technical problems of long-distance directional hole formation and full-hole screen hole protection and drainage in the downwardoblique borehole of the soft and thin coal seam,improve the drilling depth and coal seam drilling rate,realize the hole protection and drainage of the whole hole section of the downward oblique hole,ensure the gas extraction effect,provide technical support for the long-distance outburst elimination of the coal roadway strip in the soft and thin coal seam,and have a wide application range of and promotion value in similar formation conditions.
万方数据
维普
