为揭示水力压裂对煤体复电阻率的影响规律进而达到以复电阻率法评价水力压裂效果的目的，以焦作赵固煤矿无烟煤为研究对象，制作柱形煤样，建立了水力压裂复电阻率测量系统，开展了实验室水力压裂试验。采用恒定的交变电流，在0～200 kHz频率范围内，测量了水力压裂前-后煤样的电容、复电阻率模值和相位。通过分析压裂前后煤体复电阻率频散特征给出了水力压裂复电阻率响应原理，分析得到了水力压裂对煤体复电阻率的影响规律，提出了复电阻率法水力压裂效果评判指标。研究结果表明：在0～100 Hz频率范围内，煤样激发极化受频率的影响很小，可用区间内任意频率的电流来监测水力压裂;模值大小受煤中水含量的影响较大，由于水填充至压裂产生的新生裂隙，致使压裂后模值较压裂前减小，且模值曲线整体向下偏移，偏移量越大，压裂效果越好;相位的峰值点受电流频率和煤样电容容量的影响，水力压裂增加了煤样内部的裂隙，煤样电容容量发生变化，导致相位峰值点发生偏移，偏移量越大，压裂效果越好。

In order to evaluate the hydraulic fracturing effect with complex resistivity,the principle of hydraulic fracturing complex resistivity response is introduced,and a hydraulic fracturing complex resistivity measurement system is established.The capacitance,complex resistivity modulus and phase of the coal before and after hydraulic fracturing were measured in a frequency range from 0 to 200 kHz using a constant alternating current.By comparing the pre-fracturing and post-fracturing resistivity modulus and phase dispersion characteristics,the dispersion mechanism is analyzed. The results show that in the frequency range from  0 to 100 Hz,the induced polarization of coal sample is little affected by frequency,and the current with arbitrary frequency can be used to monitor hydraulic fracturing. Because of the water filling to the new fracture,the modulus value decreases after fracturing,and the modulus value curve shifts downward as a whole compared with the curve before fracturing. The larger the difference is,the better the fracturing effect is.The peak point of the phase is affected by the current frequency and the capacitance of the coal sample. The hydraulic fracturing increases the crack inside the coal sample,and the capacitance of the coal sample changes,causing the phase peak point to shift. The larger the offset is,the better fracturing effect is.

0 引言

1 煤样制备与水力压裂试验

   1.1 取样与试验过程

   1.2 水力压裂复电阻率测量

2 试验结果与讨论

   2.1 结果

   2.2 讨论

3 结论