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为了提高低渗透性煤层气的抽采效率,揭示高压电脉冲水力压裂技术对煤体产生裂缝的效果及裂缝的扩展演化规律,通过实验室试验,对煤样进行单纯静水压裂(3 MPa)和相同水压力(3 MPa)、不同放电电压(5,10 k V)条件下的高压电脉冲水力压裂试验,应用CT扫描技术分析了煤样内部裂纹的起裂、发展、分布情况;建立数值模拟分析水压电脉冲作用下裂隙的发展规律和裂缝周边的应力分布情况。研究结果表明:在相同静水压力作用下,高压电脉冲水力压裂煤层比单纯静水压力致裂效果明显;放电电压越高,在裂隙尖端产生的拉应力值越大,煤体易产生疲劳损伤破坏,裂隙易产生、易发展;放电电压越高,裂纹数量越多,裂纹的起裂时间更早,裂缝延伸长度更长,宽度更宽,致裂效果更好;可证明高压电脉冲水力压裂煤层方法有效,技术可行。
In order to improve the extraction efficiency of low permeability CBM, the effect of high pressure electrical pulse hydraulic fracturing on the cracking of coal and the evolution of cracks were revealed. Through laboratory tests, MPa) and the same water pressure (3 MPa) and different discharge voltages (5 and 10 kV), the crack initiation, development and distribution in coal samples were analyzed by using CT scanning technique The numerical simulation was carried out to analyze the development of fractures and the stress distribution around fractures. The results show that under the same hydrostatic pressure, the fracturing effect of high pressure electrical pulse hydraulic fracturing coal seam is better than pure hydrostatic fracturing. The higher the discharge voltage, the greater the tensile stress generated at the crack tip, Damage, crack easily produce, easy to develop; the higher the discharge voltage, the more the number of cracks, crack initiation time earlier crack extension longer, wider width, cracking better; can prove that high-voltage electrical pulse hydraulic The method of fracturing coal seam is effective and technically feasible.