页岩水力压裂中多簇裂缝扩展的全耦合模拟

水平井和水力压裂是页岩气开发中的关键技术。对水力压裂中多簇裂缝同时扩展的物理过程进行了数值模拟。采用扩展有限元法(XFEM)模拟岩石中裂缝沿着任意路径扩展,采用有限体积法(FVM)模拟裂缝中流体的流动,并且考虑井筒中流体流动以及在各簇裂缝间的流量动态分配。通过牛顿迭代对全耦合物理过程进行数值求解,重点研究了初始长度不同的两条裂缝的扩展过程,证明较大的射孔摩阻能促进两条裂缝的同时扩展。并通过算例证明了本方法的精度和有效性。

Fully coupled modeling for multiple clusters growth of hydraulic fractures in shale

Hydraulic fracturing in the horizontal wellbore is an effective technique in the development of shale gas.In this paper,the growth of multiple hydraulic fractures clusters is simulated numerically.The extended finite element method (XFEM) is adopted to model arbitrary propagation of the fractures in shale rock and the finite volume method (FVM) is used to discretize fluid flow in the fractures.The flow in horizontal wellbore and the dynamic distribution of the flow into different fracture clusters are consi-dered.The fully coupled field equations are solved by Newton iteration.Numerical examples are pre-sented to validate the accuracy and efficiency of the method.The propagation paths of two hydraulic fractures are modeled to demonstrate that the larger perforation entry friction can promote simultaneous growth of multiple fracture clusters.