非均匀孔隙压力下水压致裂的数值试验

Numerical Simulation of Hydrofracturing in Anisotropic Pore Pressure Fields

运用数值试验方法研究了非对称分布的孔隙压力梯度下水力压裂裂缝的扩展行为 ,数值试验再现了孔隙水压作用下岩石微破裂诱致宏观破坏的演化过程·数值试验结果表明 ,水力压裂裂纹的扩展不仅受到裂纹尖端局部孔隙水压力大小的影响 ,同时也受控于宏观上孔隙水压梯度分布 ,在扩展方向上致裂裂纹往往偏向于高孔隙压力的区域 ,并且其压裂压力随着局部孔隙压力的增大而降低 。

By using numerically testing method, hydrofracturing in anisotropic pore pressure fields was studied. The simulated results indicate the macroscopic failure evolution process induced by microscopic fracture under pore pressure, which agrees well with the experimental results. It is found that the fracture is influenced by both pore pressure magnitudes on a local scale around the crack tip and by the orientation and distribution of pore pressure gradients on a global scale. The fractures always propagate towards the regions of higher local pore pressure and fracture pressure decreases with the increasing of local pore pressure. The research may be applied to control the hydraulic fracture orientation in the field.