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    坚硬顶板定向长钻孔水力压裂卸压机理研究与工程实践

    Mechanism and engineering practice of pressure relief by hydraulic fracturing with directional long boreholes in hard roof strata

    • 摘要: 针对深部矿井坚硬顶板易形成大面积悬顶并诱发强矿压显现的问题,以园子沟煤矿1012006工作面为工程背景,开展了水力压裂卸压技术研究。通过地质勘察与关键层理论分析,确定了距巷道顶板23 m的低位关键层为压裂目标层位。采用真三轴水力压裂声发射实验,揭示了注水压力突降与声发射计数跃增的同步响应规律,建立了岩体破裂与声发射特征的定量对应关系,为现场微震监测提供理论依据。基于“双孔协同”布孔原则,设计了由6个钻场、12个定向长钻孔组成的压裂网络,总进尺5 727 m,规划压裂120段,并配套选用专用装备。监测结果表明:压裂影响半径最大达27.8 m;微震事件日均频次与总能量分别降低50.65%和27.73%;巷道深部应力降幅达17.69%。

       

      Abstract: To address the technical challenge of large-area roof hanging and induced strong strata behaviors in deep mines with hard roof strata, a study on pressure relief using hydraulic fracturing technology was conducted by taking the 1012006 working face in Yuanzigou Coal Mine as the engineering background. Through geological survey and key stratum theory analysis, a low-position key stratum located 23 m above the roadway roof was identified as the target layer for fracturing. True triaxial hydraulic fracturing experiments coupled with acoustic emission (AE) monitoring revealed a synchronous response characterized by a sudden drop in injection pressure and a rapid increase in AE counts, which established a quantitative correlation between rock mass fracturing and AE characteristics, providing a theoretical basis for field microseismic monitoring. Based on the “one-hole-two-track” borehole layout principle, a fracturing network comprising 6 drilling fields and 12 directional long boreholes was designed, with a total drilling length of 5727 m and 120 planned fracturing stages. Specialized equipment was selected for implementation. Field monitoring results demonstrated that the maximum fracturing influence radius was 27.8 m; the average daily frequency and total energy of microseismic events decreased by 50.65% and 27.73%, respectively; the stress in the deep part of the roadway decreased by 17.69%.

       

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