| Summary: | The technology and advantages are introduced about drilling down screen pipe without lifting, and a kind of large-diameter plug-in type spiral drill pipe for the screen pipe without lifting is developed, then the field tests are carried out in Sijiazhuang Coal Mine and Xinjing Coal Mine of Yangquan Coal Industrial Group. The results show that the spiral drill pipe with large-diameter plug-in type can realize the functions of forward and reverse, and can effectively solve the accidents of sticking and holding drilling. Combined with the technology of drill down the screen pipe without lifting, the method improves the hole forming rate and depth of the gas drainage borehole in this coal seam, and significantly improves the success rate of drill down the screen pipe.
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