Numerical investigation of fluid injection into poorly consolidated geomaterial considering shear dilation and compaction

We present a fully coupled poroelastoplastic finite element model to simulate micro-fracture evolution, compaction failure and tensile fracture propagation during fluid injection into poorly consolidated geomaterial. The model includes shear dilation, strain hardening and fracture process zone with permeability evolution. We investigated the effects of geomechanics (stress anisotropy) and fluid injection (fluid rheology) on rock deformation and fracture behavior. Results indicate that fluid rheology dominate the rock failure. Pore pressure increase and water wedge effect can cause two kinds of shear dilation which are prior to tensile failure. The effect of compaction is significant to tensile fracture geometries, which differ from those under elastic and poroelastic conditions. The difference between shear band and compaction zone is the transition of fracture regime from the leak-off dominated to the storage dominated governed by fluid injection.