针对现有松软煤层瓦斯抽采孔成孔性差、抽采距离短、抽采区域小等难题,采用梳状定向孔方法在松软煤层顶底板岩层施工长距离梳状钻孔,实现对松软煤层瓦斯远距离与区域抽采。根据梳状孔在松软煤层施工特点,合理选择梳状孔布孔形式,分析出在松软煤层顶底板岩层中施工梳状定向孔面临开分支、降低钻具摩擦阻力等技术难点。现场试验表明:采用控时连续滑钻实现梳状孔在岩层开分支,通过优化钻孔设计与高精度控制钻孔轨迹可有效降低钻具摩擦阻力,提高梳状孔施工安全性,可满足最大孔深大于500 m和岩层开分支施工要求。

According to the present poor borehole complement of the gas drainage borehole in the soft seam, short gas drainage distance, small drainage area and other difficulties, the comb type directional borehole method was applied to the comb type borehole drilling with a long distance in the roof and floor strata of the soft se am and thus a longdistance and regional gas drainage in the soft seam could be conducted.According to the construction features of the comb type borehole drilling in t he soft seam and to the rational selection of the comb type borehole pattern, the emergent branching operation of the comb type directional drilling in the roof and floor strata of the soft seam, the reduction of the drilling tools friction resistance and other technical difficulty were analyzed.The site trial showed that the time control contin ued sliding drilling was applied to make the branching of the comb type drilling in the rock strata.With the optimized design of the borehole and the high accuracy contro lled borehole tracing, the friction resistance of the drilling tools could be effectively reduced, the safety of the comb type drilling operation could be improved and the re quirements of the max borehole depth over 500 m and the branching operation in the rock strata could be met.

“十一五”国家科技重大专项基金资助项目(2008ZX05041-003)；