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水力压裂计算对页岩气开采至关重要,将岩体等效为均匀多孔介质,以动力达西–毕奥流描述岩体内的渗流过程,以相场方法追踪裂缝扩展,将压裂裂缝内流体近似为泊肃叶流,并通过修正渗流方程予以实现,从而提出了动力水力压裂的相场模拟方法,并基于显式有限元框架进行数值求解。通过与一维解析解对比说明所提方法计算位移和动水压的准确性。一系列数值算例表明,提出的压裂相场模拟方法能够模拟动力水力压裂作用下裂缝动态扩展的典型特征,且能够计算水力压裂裂缝的相交、分叉和三维扩展等复杂裂缝扩展形态,为动力水力压裂设计提供了强有力的数值计算工具。
Hydraulic fracturing calculation is very important for shale gas exploitation. The rock mass is equivalent to a uniform porous medium. The dynamic Darcy-Biot flow is used to describe the seepage process in the rock mass. The phase propagation method is used to track the fracture propagation. The fracturing The fluid in the fracture is approximated as Poiseuille flow, which is achieved through the modified seepage equation. The phase field simulation method of dynamic hydraulic fracturing is proposed and the numerical solution is carried out based on the explicit finite element framework. The proposed method is compared with the one-dimensional analytical solution to calculate the displacement and hydrodynamic accuracy. A series of numerical examples show that the proposed fracturing phase field simulation method can simulate the typical characteristics of dynamic fracture propagation under dynamic hydraulic fracturing and can calculate complex crack propagation modes such as intersection, bifurcation and three-dimensional expansion of hydraulic fractures , Which provides a powerful numerical calculation tool for dynamic hydraulic fracturing design.