In this paper, we present a new computational framework to simulate reservoirs containing complicated geological and engineering features (for example, faults, induced or natural fractures, and perforations). Unlike traditional computational methods, the new approach does not require the mesh to honor the geometrical shapes of subsurface features. The effects of these features on the solution are captured by enriching the finite element approximation based on the Partition of Unity theory.
This new simulation capability eliminates the laborious meshing work traditionally required for modeling complicated subsurface features without compromising solution accuracy. It is especially useful in the detailed analysis of near-well physics where subsurface features at this scale need to be modeled both accurately and efficiently. In cases where the subsurface features are evolving, the computational mesh does not have to know a priori the shape of the evolving subsurface features. This method is particularly useful in the study of curvature changes of hydraulic fractures due to evolving stress fields away from the well.
A number of examples are given to demonstrate the effectiveness of the proposed approach. The examples are grouped into three broader application areas: (1) well performance analysis of fractured completions, (2) deformation characteristics of reservoirs containing fracture networks, and (3) simulation of fracture interference and re-orientation.