为了提高煤矿井下单一低渗煤层瓦斯抽采效果，基于普通中、短钻孔水力压裂技术在瓦斯治理方面存在的弊端，结合煤储层地质条件和定向钻进技术特点，提出了井下定向长钻孔水力压裂瓦斯高效抽采技术，总结了长钻孔整体压裂和围岩梳状孔分段压裂2种水力压裂模式，分析了施工工艺和关键技术，以阳泉矿区为例，进行了定向长钻孔水力压裂试验，并考察了其效果。结果表明：长钻孔整体压裂采用基于扩张式封隔器原理的快速封孔技术，可在10 min内实现封孔工具组合快速坐封。梳状孔分段压裂施工采用裸眼封隔器滑套分段压裂工艺，利用孔口投球方式依次打开各级投球滑套，完成各个分支钻孔注水压裂作业。水力压裂影响范围内煤体全水分随着与钻孔距离的增大呈现先增大、后减小的现象，煤层瓦斯含量与煤体全水分呈现相反的分布特征。压裂过程中巷道受力变形现象明显，放喷初期水流大量携粉，排粉量达到6.5 t。长钻孔整体压裂和梳状孔分段压裂的最大影响半径分别达到58 m和60 m，比常规压裂钻孔增大2.32倍和3.53倍，平均瓦斯抽采纯量达1.51m³/min和0.25m³/min，比常规压裂钻孔提高24.40倍和13.89倍。分析认为压裂过程存在水驱气效应，且压裂对煤储层改造效果在空间上存在不均衡性。煤岩体吸水后发生体积膨胀和软化现象，改变了钻孔周围应力场的分布，导致了巷道受到挤压破坏发生变形。梳状孔分段压裂过程中围岩中裂缝通过牵引作用与煤层中压裂裂缝沟通，进而形成新的煤储层裂隙网络系统，有利于提高瓦斯抽采效果。指出下一步应在地质选区、压裂参数和压裂工艺优化设计、压裂效果监测技术等方面展开深入研究，构建完善的井下定向长钻孔水力压裂瓦斯高效抽采技术体系。

In order to improve the gas drainage effect of a single coal seam with low permeability in underground coal mines, based on the shortcomings of the gas fracturing technology of ordinary medium and short borehole hydraulic fracturing, combined with the geological conditions of coal reservoirs and the characteristics of directional drilling technology, a high-efficiency gas drainage technology of directional long borehole hydraulic fracturing is put forward, and the overall pressure of long borehole is summarized.Two hydraulic fracturing modes-integral fracturing and comb-shape borehole fracturing in surrounding rock are introduced.The construction technologies and key technologies are analyzed.Taking Yangquan mining area as an example, the directional long borehole hydraulic fracturing test was carried out and its effect was investigated.The results show that the fast fracturing technology based on the principle of expandable packer can be used for integral fracturing of long boreholes, and the fast setting of combination of sealing tools can be realized within 10 minutes.The slip sleeve fracturing technology of bare-hole packer was adopted in the section fracturing of comb hole, and the slip sleeve of all levels was opened in turn by the way of hole opening shot, thus the water injection fracturing operation of each branch of comb-shape borehole was completed.With the increase of the distance from the borehole, the total water content of the coal in the influence range of hydraulic fracturing first increases and then decreases, and the gas content of the coal seam has the opposite distribution characteristics to the total water content of the coal body.During the fracturing process, the stress and deformation of the roadway were obvious.In the initial stage of the ejection, the water flow carried a large amount of powder, and the powder discharge amount reached 6.5 t.The maximum influence radius of integral fracturing with long boreholes and sectional fracturing with comb-shape boreholes are 58 m and 60 m respectively, which are 2.32 times and 3.53 times larger than that of conventional fracturing boreholes.The average gas drainage volume is 1.51 m3/min and 0.25 m3/min, which are 24.40 times and 13.89 times higher than that of conventional fracturing boreholes.The analysis shows that there was a water flooding effect in the fracturing process, and there was a spatial imbalance in the effect of fracturing on the coal reservoir transformation..The phenomenon of volume expansion and softening occurs after water absorption of coal and rock mass, which changes the distribution of stress field around boreholes, and leads to the deformation of roadway under compression damage.During the staged fracturing of comb holes, the fractures in the surrounding rock communicate with the fractures in the coal seam through traction, thereby forming a new coal reservoir fracture network system, which is conducive to improving the gas drainage effect.