桑树坪二号井3号煤层底板穿层钻孔水力扩孔技术应用

Application of hydraulic reaming technology of No.3 coal seam floor layer-crossing borehole in Sangshuping No.2 Mine

桑树坪二号井深部四采区3号煤层瓦斯含量高、瓦斯压力大、地应力高、透气性差、煤体松软、突出危险性严重、常规穿层钻孔抽采煤层瓦斯难度大,效率低等技术痛点亟待解决。通过高压水射流钻扩一体化卸压增透工艺技术对比试验得出,扩出煤屑率分别为0.75%、2.35%时,钻孔直径扩大了3倍、8倍,百米钻孔瓦斯流量提高了1.3倍、3倍,瓦斯浓度提高了1.5倍、1.8倍,抽采效率提高了28%以上。排出大量煤屑后,煤层暴露面积和煤层卸压范围增加,可抽采性显著改善,瓦斯抽采效果明显提高,是实现矿井瓦斯高效抽采,纾缓采掘抽紧张关系的重要技术路径。

The 3#coal seam of deep fourth mining area of Sangshuping No.2 Mine is of high gas content,high gas pressure,high geo-stress,poor permeability,soft coal,and serious outburst hazard.It is urgent to solve the technical issues of difficult layer-crossing drilling gas extraction of coal seam with low efficiency.Through comparative experiments on the drilling-enlarging integrated technology for pressure relief permeability-enhancing with high pressure water jet,we find that when the discharged coal debris was 0.75%and 2.35%,respectively,the borehole diameter is enlarged 3 times and 8 times,hectometer borehole gas flow is increased 1.3 times and 3 times,gas concentration boosted 1.5 times and 1.8 times,and extraction efficiency improved more than 28%.After discharging mass coal debris,the exposed area and pressure-relief range of coal seam are enlarged,and the extraction is significantly improved with obviously better effect to relieve the strained relations of wining-driving-extraction and achieve high efficiency extraction of mine gas.