[Description]
A finite volume-based arbitrary fracture propagation model is used to simulate fracture propagation and geomechanical stresses during hydraulic fracture treatments. Single-phase flow, Biot’s displacement, and in-situ stress tensor equations are coupled within a poroelastic reservoir domain, using a fixed-strain split assumption. The domain is idealized as two-dimensional and plain-strain, with heterogeneous elastic material, fluid flow, and fracture toughness properties. Modeled fracture propagation proceeds by failure along finite volume cells in excess of a threshold effective stress.

[Application/Development]
The model is used to simulate propagation of non-planar fractures in heterogeneous porous media under uniform, anisotropic stresses. In addition the model computes the stress contrast and the pore pressure in the rock matrix to account for stress interference effects. This allows us to estimate the simulated micro-seismic signature of the rock during fracturing. Results show that the presence of bedding planes or planes of weakness in the rock can lead to complex fracture trajectories. The growth of multiple, non-intersecting, competing fractures is also simulated.

[Results/Conclusions]
It is shown that the fracture geometry obtained using this model is highly dependent on the pattern of heterogeneity. For homogeneous reservoirs and a high in-situ stress contrast, planar fractures are obtained. As the stress contrast is decreased and the degree of heterogeneity is increased, fracture complexity increases. Results for different kinds and levels of formation heterogeneity, planes-of-weakness such as bedding planes, natural fracture networks, and layers with different mechanical properties are presented.

[Significance of Subject]
This model allows for first-of-kind simulation of propagation of fractures with arbitrary fracture geometry in a poroelastic solid domain using proven finite volume cohesive zone methods. The effect of fluid backpressure, mechanical stress shadow effects, and the presence of planes of weakness is accounted for. The effect of formation heterogeneity is explicitly accounted for and quantified for the first time. The implications of this more complex fracture geometry are discussed with respect to proppant transport and reservoir drainage.