Abstract: To improve the borehole sealing technique of horizontal gas drainage for low permeability and high gassy single coal seam, the “strong-weak-strong” borehole pressurized sealing technology was developed in this paper, and the technology was practically applied in N1-3 Coal Face of Changcun Coal Mine. The practical results show that the technology has siginificant sealing effect, and the effect is increased by times against those of the common ways under the same conditions, namely, the gas extraction concentration increases from 26%~33% to 61%~64%, and the accumulated extraction time of single-hole with 470 m3 gas decreases form 10 d to 3 d. After its implementation in Changcun Coal Mine, the gas extraction concentration and gas accumulated quantity in tailentry of N1-3 Coal Face have been significantly improved. Thus, this technology has provided a new technical measure for borehole sealing in the condition of high gas contents, and has significant economic and social benefits.

Key words: low permeability coal seam, borehole sealing, strong-weak-strong, borehole pressurized sealing, gas extraction