Application Study on Wall Protection Technology with PVC Pipe in Gas Drainage Hole in Soft Seams

Abstract:

Geological structure is complex with soft seams and poor permeability in Zhaozhuang coal mine of Shanxi. Wall collapse of gas drainage hole caused by unstability leads to gas drainage channel blocking, low extraction rate and poor drainage effect. By the technology that drill pipe is kept at the completion of drilling construction and in which gas extraction screen liner is lowered to protect the wall, gas drainage channel can be formed after drill pipe is lifted. The application results show that the pipe lowering efficiency is largely improved comparing with that of traditional drill casing technology. The pipe length is up to more than 98% of the hole depth, which is helpful to improve the efficiency of gas drainage and has great significance for coal mine safety.

Key words:soft seams; gas drainage hole; wall protection technology; PVC pipe