Production from naturally and hydraulically fractured reservoirs is highly dependent on the complex fracture geometry of the fracture network. It is computationally very expensive to model the mechanics, closure and flow of each individual fracture in a large domain with thousands of fractures. We propose a workflow to convert the discrete fracture network (DFN) of fractures into an effective permeability tensor that can be used to simulate flow in such complicated fracture networks.

A discrete fracture network (DFN) of natural fractures is stochastically generated and the displacement discontinuity method based hydraulic fracturing simulator (Multi-Frac-NF) is used to model the hydraulic fracture propagation. This created fracture network along with induced unpropped (IU) fractures are imported into a geomechanical reservoir simulator. During flowback, the permeability tensor for the stimulated reservoir volume (SRV) is calculated. The effect of fracture height and natural fracture orientation on effective permeability tensor of SRV is systematically investigated.

We show that the propagating hydraulic fracture can generate enough stress perturbations to allow hydraulically disconnected natural fractures to fail in its vicinity. These disconnected IU fractures can also increase the effective permeability of the reservoir close to the hydraulically connected fracture. Simulation results indicate that the effective permeability of the SRV is a strong function of the natural fracture orientation and hydraulic fracture height.

We propose a workflow which includes the coupled effect of geomechanics and reservoir flow on the estimation of the effective permeability tensor for the SRV. The workflow presented in this paper provides a novel method to generate the reactivated natural fracture network around propagating hydraulic fractures and to capture the behavior of complex fracture networks in simplified reservoir simulation models using an effective permeability tensor for the SRV.