Study on gas drainage technology by using large aperture high level borehole

In order to resolve the problem of slow progress on gas control engineering and long period of excavation replacement,this paper studied on gas drainage technology using large aperture high level borehole.The precondition of high level borehole layout within reason is acquisition with accuracy of fissured zone boundary,which influences gas drainage effect directly.Fissured zone boundary located on the top of coal bed from 6.59m to 46.24m by using distinguishing method based on key stratum theory,and then the conclusion was checked up by using numerical simulation.Field test results show that gas drainage using large aperture high level borehole achieves good effect,average drainage concentration is 37.3% and average drainage flow is 11.58m³/min in the course of high consistency,then the phenomenon of gas exceeding the limit usually occurs in working face is avoided.