顶板多层位定向割缝高压致裂防冲技术

    Technology of High Pressure Hydraulic Fracturing and Rock Burst Prevention by Multi-layer Directional Slotting in Roof

    • 摘要: 为了实现坚硬顶板型冲击地压防治的安全高效可控,研究了多层位定向割缝高压致裂技术。采用UDEC数值模拟研究了顶板定向致裂前后的运动与能量释放规律。结果表明:坚硬顶板经倾斜与分层定向致裂后,来压步距分别降低了7.7%与17%;系统动能释放降低了47.8%与50%,系统总能量释放降低了28%与41%,从而减弱了对煤体的冲击效应。顶板分层以及多层位定向致裂防冲效果优于倾斜切顶。通过改进供液与送管工艺,实现此技术的自动化与孔深限制,拓展了技术的效率与安全性,最大孔深达到20 m,致裂半径10 m以上。现场钻屑法与微震监测结果表明,致裂顶板区域,钻屑量较致裂前明显减少,并均低于临界值,致裂期间与区域内震动频次与震动能量降低,尤其是大能量震动信号显著减少,表明冲击危险性显著降低,证明此技术防治顶板冲击地压的有效性。

       

      Abstract: In order to promote the controllable safety and efficiency of the hard roof in coal mines, this paper studies the multi-layer directional high pressure fracturing technology. The UDEC numerical simulation was used to study the kinetic and total energy release of the roof before and after directional hydraulic fracturing. The results show that the weighting interval is reduced by 7.7% and 17% respectively after the hard roof is inclined and layered fracturing. The maximum kinetic energy release is reduced by 47.8% and 50%; the system total energy release is reduced by 28% and 41%, which reduces the risk of rock burst caused by hard roof. By improving the liquid supply process, the depth limitation of the technology is realized, and the efficiency and safety of the technology are greatly expanded. The maximum hole depth is 20 m and the cracking radius is more than 10 m. The results of drill cutting and micro-seismic monitoring results show that the amount of cuttings in the fractured roof area is significantly lower than that before the fracturing, and both are lower than the critical value. The frequency and energy of seismicity during the hydraulic fracturing period are reduced, especially the large energy seismic signal, which indicates a significant reduction in rock bust risk and also demonstrates the effectiveness of this technology in the controlling of hard thick roof in coal mines.

       

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