压裂钻孔孔壁破坏行为与注水流量相关性试验研究

为分析流量对水力压裂钻孔起裂特征的影响，开展了不同注水流量水力压裂实验，得到了煤体起裂过程的孔壁压缩应变-水压曲线。结果表明，流量的增大使破裂形态趋于复杂，表现在裂缝的数目及宽度会变多增大，而原煤则更易于沟通原生裂隙；对于无明显节理的配比型煤，随着注水流量增大，孔壁应变速率和起裂压力均增高；对于含明显节理的原煤，孔壁应变速率及起裂压力变化具有一致性，但与流量变化不一致，原煤内部的节理会影响试块起裂行为，降低钻孔内能量积聚速率和煤体破裂强度。研究成果对于揭示钻孔起裂行为具有重要理论意义，为水力压裂实验研究提供了一种新思路。

Experimental study on correlation between water injection flow rate and hole wall failure behavior of hydraulic fracture borehole

In order to analyze the influence of flow rate on fracturing initiation characteristics of hydraulic fracture borehole, the hydraulic fracturing experiments under different water injection flow rates were carried out, and the curves of hole wall compressive strain against water pressure in the fracturing initiation process of coal were obtained. The results showed that the fracture morphology of coal samples tended to be complicated with the increase of flow rate, with the representation of larger number and width of cracks, and the initial fissures became easily to link up for raw coal samples. For proportioning briquette without obvious joints, the hole wall strain rate and the fracturing initiation pressure increased with the increase of water injection flow rate. For raw coal with obvious joints, the hole wall strain rate and the fracturing initiation pressure variation had the consistence, while did not show consistence with flow rate variation. The internal joints of raw coal would influence the fracturing initiation behavior of coal samples in aspects of decreasing the energy accumulation velocity in borehole and the fracture strength of coal samples. It has important theoretical significance to reveal the fracturing initiation behavior of borehole, and provides a new idea for experimental research on hydraulic fracturing.