Recently, borehole sidetrack flying pipe deploy technology developed by CCTEG Xi'an Research Institute (Group) Co., Ltd., achieved breakthrough successfully in the application of soft coal directional drilling in Zhangji Coal Mine. on the basis of comb hole technology of coal mine with independent intellectual property rights. The hydraulic directional drilling technology is used to complete the main hole construction of floor strata, and the pneumatic directional drilling technology is used to complete multiple holes of soft coal to realize long distance distribution. After the holes are formed, the screen pipe of hole protection is placed into the coal hole branch. The problems such as the depth and difficulty of hole protection in the branch of comb borehole in soft coal seam are solved successfully. At present, three comb holes of soft coal have been completed, with a maximum hole depth of 468m and a maximum fly pipe depth of 202m, which has improved the gas extraction effect.
