煤矿定向长钻孔水力压裂防冲技术研究

Hydraulic fracturing technology for preventing rock burst with directional long boreholes in coal mines

  • 摘要: 【目的】针对煤矿坚硬顶板垮落难、易引发动力及瓦斯灾害的问题,以蒋家河煤矿ZF1412工作面为背景,研究顶板定向长钻孔水力压裂防冲技术,弱化坚硬顶板、降低应力集中,为同类矿井安全开采提供技术支撑。【方法】分析工作面地质条件确定5~29 m砂岩为压裂目标层位,设计高位定向长钻孔分段压裂方案,采用封隔器管柱系统实施倒退式分段压裂;以微震监测为主,结合泵压流量、巷道应力变形监测,从微震能量、高能事件、巷道变形速率维度分析压裂卸压效果。【结果】压裂后工作面压裂区域微震总能量下降55.8%,104 J以上高能微震事件减少60%,回风顺槽巷道变形速率降幅58.3%,顶板应力集中显著降低,巷道稳定性大幅提升。【结论】该技术可有效弱化坚硬顶板、形成裂隙网络实现卸压,防冲效果显著,可为彬长矿区同类矿井提供参考;后续可增加压裂孔数、加大压裂强度,进一步提升治理效果。

     

    Abstract: Aiming at the problems of difficult caving of hard roof and frequent occurrence of dynamic disasters and gas disasters in coal mines,takes the ZF1412 working face of Jiangjiahe Coal Mine as the engineering background, and studies the roof directional long borehole hydraulic fracturing technology for rock burst prevention. The technology is applied to weaken the hard roof and reduce stress concentration, so as to provide technical support for the safe mining of similar mines.By analyzing the geological conditions of the working face, the sandstone formation at 5~29 m is determined as the target fracturing layer. A staged fracturing scheme for high-level directional long boreholes is designed, and the retrogressive staged fracturing is implemented by adopting a packer string system. With microseismic monitoring as the core method, combined with pump pressure and flow monitoring as well as roadway stress and deformation monitoring, the fracturing and pressure relief effect is analyzed from the dimensions of microseismic energy, high-energy events and roadway deformation rate.After fracturing, the total microseismic energy in the fracturing area of the working face decreases by 55.8%, the number of high-energy microseismic events above 104 J is reduced by 60%, and the deformation rate of the air return gateway drops by 58.3%. The stress concentration of the roof is significantly alleviated, and the roadway stability is greatly improved.This technology can effectively weaken the hard roof and form a fracture network to realize pressure relief, with remarkable rock burst prevention effect, which can provide a reference for similar mines in the Binchang mining area. In the follow-up, the number of fracturing boreholes can be increased and the fracturing intensity can be enhanced to further improve the governance effect.

     

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