Modeling of Failure Along Predefined Planes in Fractured Reservoirs

Abstract

A numerical approach to model stress and failure in fractured reservoirs, including slip along predefined planes, is presented. The model is based on linear elasticity theory and uses the static/dynamic friction law. The displacement vector is computed by a finite volume method, and in addition to the discretization of the whole domain, the fractures are discretized by lower dimensional segments. After every time step it is decided individually for each of these fracture segments, whether the specified slip criterion based on the static/dynamic friction law is reached. A numerical scheme coupling irreversible slip along the segments with the elastic displacement in the domain is developed. The irreversible slip information, which also matters for the stress calculation, is stored and used in a mathematically consistent way at each adjacent finite volume interface, i.e. the actual grid geometry remains unal-tered. The coupled system for elastic displacement and irreversible slip is solved by an implicit solver. The method is implemented in two dimensions for multiple fractures, and a number of numerical simulation studies have been performed to analyze the stress distribution adjacent to single fracture and fracture networks.