Chongqing Research Institute,China Coal Technology and Engineering Group National Key Laboratory of Gas Disaster Detecting,Preventing and Emergency Controlling

in order to efiectively drainage gas from the neighboring seams and the goa .high level directional ong borehole was proposed to be appied to replace he roof high level gas drainage gatewvay for gas drainage.Aceording to a high res stance of the driling and other problems inthearling constution in Hongyang No.3Mine ,a rlling techrical experiment combined with the directional iling and borehole rotary reaming and ad iling technical experiment on th different camber dowohole motor and dfferent diameter ling bit was conducted.The experiments showed tht a 1.25' bending down hole motor with a gp96 mn drling bit was applied to N0.3- 5 borehole driling.a high pushing res stance problem occured at the 350 m of thedrlling .a g153 mm driling bit vas appied to the reaning of the borehole to 32m,which could dil an acittonal lngth of 120 m.A 1.25 bending down hole maotor with a o104 m rllig bt was applied to No.3-2 borehole driing and the boreholedepth was 610 m.A 1'bending down hole motor with a p100 mm d lling bit was applied to No.3-3 borehole drlling and the borehole depth was 616 m.The bending angle reduced down hole motor and the drling bit dameter increased could eff ctively reduc.e the pushing resistance and could obwiously increase the d iing depth

国家科技重大专项资助项目(2011ZX05041-001-002)；