Hydraulically driven branching fracture

This problem contains basic test cases for one or more Abaqus elements and features.

The test in this section verifies the hydraulically driven branching fracture propagation using the pore pressure cohesive elements with the fluid transition from Darcy flow to Poiseuille flow.

This page discusses:

ProductsAbaqus/Standard

Elements tested

  • COD2D4P

Problem description

The test verifies the crack branching functionality by using the pore pressure cohesive elements with the fluid transition from Darcy flow to Poiseuille flow. The model simulates the hydraulic fracture growth with existing cracks. There are three branches of cohesive zones: a vertical branch and two horizontal branches. The two horizontal branches represent preexisting cracks, and the vertical branch simulates progressive fracture by hydraulic injection. The material strength is weakened for the horizontal branches to simulate the preexisting cracks. Confining pressure is prescribed around the whole domain. Contact with friction is prescribed to the cohesive zone top and bottom surfaces to study the role of friction on the crack propagation into preexisting fracture.

Results and discussion

The results match the results presented in Zhang and Jeffrey (2006). When the fracture propagates into the horizontal branches, the crack changes mode from tension into shearing, the injection pressure increases, and the crack width decreases. The friction coefficient value between the top and bottom surfaces of the cohesive zones plays an important role in how the fluid gets into the preexisting fractures and how the horizontal fracture propagates.

Input files

ac-nogap5c.inp

Plane strain model using COD2D4P and CPE4 elements.

References

  1. Zhang,  X.,  and R. G. Jeffrey, “The Role of Friction and Secondary Flaws on Deflection and Re-initiation of Hydraulic Fractures at Orthogonal Pre-existing Fractures,” Geophysical Journal International, no. 166, pp. 1454–1465, 2006.