厚硬顶板垂直井压裂矿震防治实践与应用

Practice and application of mine tremor prevention and control for vertical well fracturing in hard thick roof

  • 摘要:
    目的 为探索地面垂直井压裂技术在深部高矿压回采工作面防治矿震效果,
    方法 以大海则煤矿20103工作面为例,通过分析压裂过程压力曲线变化和裂缝发育范围以及工作面回采至压裂区域前后周期来压强度、地表沉降速率、微震数据演化规律等验证地面垂直井防治矿震效果。
    结果 研究结果表明,足够的压裂压力可起到破岩效果,使岩体持续产生裂缝。地面垂直井压裂过程形成了规模适中、空间展布稳定的人工裂缝,有效弱化了工作面上覆厚硬顶板整体性。工作面进入压裂区后,顶板来压步距、来压强度及来压持续时间均明显减小;地表沉降速率显著提升,较工作面未进入沿空前提高2.67倍、工作面进入沿空未压裂区提高2.18倍,覆岩沉降变形得以提前充分运动。压裂区微震日均与延米能量有所增加,但未发生104 J及以上大能量事件,顶板破断高度降低,微震活动向远离煤壁方向转移,实现了厚硬顶板弱冲击、低能级、分散化的破断卸压效果。
    结论 地面垂直井压裂可预裂弱化厚硬顶板、分散释放集中应力、降低矿压显现、抑制高位强破断,有效降低深部高矿压厚硬顶板快速回采工作面发生矿震的风险。

     

    Abstract: To investigate the effectiveness of surface vertical well fracturing technology in preventing and controlling mine tremors at deep, high mine pressure working faces, a case study was conducted at the 20103 working face of Dahaize Coal Mine. The control effect was verified by analyzing the pressure curve variations and fracture development extent during fracturing, as well as the periodic weighting intensity, surface subsidence rate, and microseismic data evolution before and after the working face entered the fractured zone. The results show that: Sufficient fracturing pressure can break the rock and cause continuous fractures in the rock mass. The surface vertical well fracturing process created artificial fractures of moderate scale and stable spatial distribution, effectively weakening the integrity of the thick and hard roof overlying the working face. After the working face entered the fractured zone, the roof weighting interval, weighting intensity, and weighting duration all decreased significantly. The surface subsidence rate increased markedly—2.67 times higher than before the working face entered the gob-side area and 2.18 times higher than when it entered the unfractured gob-side area—allowing the overburden subsidence deformation to develop fully in advance. In the fractured zone, the daily average and per-linear-meter microseismic energy increased somewhat, but no large energy events of 104 J or above occurred. The roof break height decreased, and microseismic activity shifted away from the coal wall, achieving a pressure-relief effect characterized by weak impact, low energy levels, and decentralized breaking of the thick, hard roof. Surface vertical well fracturing can pre-fracture and weaken the thick, hard roof, disperse and release concentrated stress, reduce mine pressure manifestation, suppress high-level violent fracturing, and effectively lower the risk of mine tremors in rapidly advancing deep working faces with high mine pressure and thick, hard roof.

     

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