Experimental study on integrated drilling， punching and protection technology for permeability enhancement in Huaibei mining area

Abstract:

Hydraulic punching to enhance permeability is an effective means of strengthening gas governance in soft and low-permeability coal seams. In response to the problems of poor permeability of coal seams， low gas extraction rate of drill hole， and long extraction cycles in the Huaibei mining area， integrated drilling， hydraulic punching and protection technology for permeability enhancement has been proposed. Research on the integrated drilling， punching and protection device has been carried out. With the use of this device， matched with large hole triangular spiral drill rods and on-off type drill bit， the integrated construction process of drilling hole， hydraulic punching for permeability enhancement， and screen pipe completion is achieved. The entire process of this technology only requires one drilling， and experiments have been carried out in Yangliu mine， and successfully drilling 29 holes. The experimental results show that the integrated drilling， punching and protection technology can achieve the integrated construction of drilling， hydraulic drilling， and screen pipe protection， avoiding the need for secondary drill pipe run for screen pipe completion， effectively improving the overall construction efficiency. After hydraulic punching through the coal section， the average volume of coal flushing reached 1.1m³/m， and the average hole diameter reached 0.93~1.0m， greatly improving the permeability enhancement effect in fragmented soft coal seams.