The Discussion About Gas Drainage From The Work Face by Surface L-borehole

, the CMM drainage technologies with the displacement and depressurization of mining coal rock, involving coal seam roof, depressurization and enhanced permeability of protective coal seam, and mining influence zone of surface drilling drainage, and the intensified CMM drainage technologi.

Currently, in order to control gas and enhance CMM recovery, various methods are adopted in Jixi Coal Mining Area such as upper roadway CMM drainage of low-permeability coal seams, upper near-horizontal hole drilling, coal seam plus-angle hole drilling, and roof large-diameter horizontal hole drilling, with satisfactory drainage results.

Authors of the paper have introduced the basic principle of in-seam gas release and movement, set forth the distribution of stress and fractures in longwall face, analyzed factors affecting gas extraction efficiency and drawn a comparison of gas extraction between two different mining methods in UK coal mines.

Hence,strata control theory can be used in gas extraction and control of coal and gas outburst.

Test results of surface gas extraction technology from boreholes in the goaf in Zhangbei Coal Mine, Huainan Mining Group are introduced in the paper.

Based on gas storage characteristic of coal seams,a gas extraction method used in coal mines is discussed.

Secondly, according to the occurrence condition of far distance coal seams in this area, numerical model was set up to simulate rock stratum displacement law, pressure relief’s characteristics and deformation rule of protected coal seam, which provided a theoretical foundation to realise the harmonic mining of gas extraction and coal.