One-step Hole Forming Technology and Device Based on Large Aperture Casing Drilling

Through the analysis of the borehole collapse phenomenon after drilling under complex geological conditions of soft and low permeability coal seam, aiming at the problem that the gas extraction hole is blocked and the screen pipe cannot be lowered, a new hole forming technique based on large diameter casing drilling is proposed, and a supporting large diameter casing drilling device is developed. The validity and reliability of the process and device are proved by the industrial test in underground coal mine.