  This paper proposes a phase field model for fracture in poroelastic media.
The porous medium is modeled based on the classical Biot poroelasticity theory
and the fracture behavior is controlled by the phase field model. Moreover, the
fracture propagation is driven by the elastic energy where the phase field is
used as an interpolation function to transit fluid property from the intact
medium to the fully broken one. We use a segregated (staggered) scheme and
implement our approach in Comsol Multiphysics. The proposed model is verified
by a single-phase solid subjected to tension and a 2D specimen subjected to an
increasing internal pressure. We also compare our results with analytical
solutions. Finally, we show 2D and 3D examples of internal fluid injection to
illustrate the capability of the proposed approach.

Geophysics;Fluid Dynamics