Abstract:
To address the issues of low gas extraction efficiency and poor sealing quality in low-permeability high-gas coal seams in Guizhou Region, especially the problems of drilling string leakage and water accumulation retention under water-rich geological conditions, and to support the prevention and utilization of coal mine gas disasters, a targeted gas control technology research is conducted based on the 110106 working face of Miluo Coal Mine(with a burial depth of 345 m and an original gas content of 10.91 m
3/t). A collaborative technical system of “drilling control-fracture filling-sealing optimization - water drainage” is constructed: the “five-step” process control during drilling construction is adopted to ensure the accuracy of drilling position, and grouting filling of fractures is used to solve the problem of drilling string leakage; the “three-seal and two-injection” sealing technology and the “cleaning-precise lowering-high-pressure” integrated sealing technology are developed to block the backflow of water and sand and the leakage of gas; the drainage control measures for water accumulation are implemented to eliminate the dilution effect of water accumulation on gas extraction. The results show that this technical system effectively solved the core problems of gas extraction in water-rich and high-stress conditions, and the gas extraction concentration of 60 out of 19 test drilling holes exceeded 50%; the 23 circulation areas of the 110106 transportation alley are verified, and the
K1 value of drill cuttings gas desorption indicators in all 23 areas is less than 0.36, and the gas concentration after blasting is reduced by 0.2%-0.3% compared to the optimized before, achieving the goal of “in-place, sealed, and water drained dry” for the drilling holes. The gas and water disaster collaborative control technology proposed in this study can significantly improve the gas extraction efficiency and outburst safety of low-permeability water-rich high-gas coal seams, providing reliable technical references for the efficient gas extraction and resource utilization of similar mines.