Modeling hydraulic fracture propagation in a saturated porous rock media based on EPHF method

Hydraulic fracture propagation in a porous rock media is complex. This paper presents an extended permeability-based hydraulic fracture (EPHF) modeling method for porous rock media. The EPHF model is a smeared crack model that is based on a fully-coupled, fluid-solid formulation. The pre-failure deformation of the solid phase is modeled by poroelasticity and the Drucker-Prager plasticity model is used for the post-fracture process. The flow liquid phase is described by Darcy's law. An extra material parameter that characterizes the onset of cracking for the brittle material is integrated into the smeared equation. Three models are integrated into the EPHF method for calculating the relative permeability when considering the mixture feature of the in-situ fluid and injected fluid. In addition to simulating fracture propagation in a homogeneous porous rock media, the EPHF model is good for simulating the fracture propagation in various heterogeneous rocks when incorporating static level set functions to describe material interfaces. An approximate method is discussed for estimating the effective hydro-fracture features; i.e., the equivalent fracture zone, fracture path and fracture aperture. Influence factors, e.g., the material properties and effective stress ratio for breakdown pressure and propagation pressure, are studied in a homogeneous fully saturated porous rock. Comparison with analytical results indicates that the EPHF method is capable of being used to model these characteristics and the hydraulic fracture propagation in a porous rock media with or without heterogeneity included.