Research on pneumatic-hydraulic composite directional drilling and fixed point grouting technology
Zhang Zhigang 1，2
1. Chongqing Research Institute Co., Ltd., Chongqing 400037, China; 2. National Key Laboratory of Coal Mine Disaster Prevention and Control, Chongqing 400037, China
Aiming at the problems of complex geological conditions of coal seam, low efficiency of traditional drilling rig, difficult treatment of gas drainage borehole collapse area and low hole-forming rate, a precise detection and collapse treatment technology of coal seam based on pneumatic-hydrodynamic composite directional drilling technology is proposed. Through the pneumatic drilling tool to construct the coal hole section ( to avoid the expansion of mudstone in water ), the hydraulic drilling tool to construct the rock hole section ( to improve the drilling efficiency ), the borehole peeper is used to identify the characteristics of the coal-rock interface, and the DDZJ96 fixed-point grouting sealing device is used to accurately fix-point grouting in the hole collapse area to strengthen the stability of the hole wall. Based on Kriging interpolation method, a three-dimensional geological model of coal seam is constructed to guide the optimization of borehole trajectory. The field test shows that the drilling rate is increased to 87.5%, the gas extraction concentration is increased by 82.9%, and the effective extraction radius is 3.0 m ( pre-drainage for 90 d ). This technology provides an efficient and accurate solution for gas control in outburst coal seams.
