Hybrid Mesh Generation for Reservoir Flow Simulation in CPG Grids

In this paper, we introduce a new method to generate a hybrid mesh from a CPG (Corner Point Geometry) reservoir grid and a radial mesh around a well. The method is an extension of the approach proposed in [1] to the case of CPG grids with high level of deformation. This ensures a fully functional mesh generation for realistic cases. The main idea is first to construct a mapping between the real space containing the CPG grid along with the radial mesh of the well and a virtual space where the CPG reservoir grid becomes a Cartesian grid. Then, because this mapping damages the circular property of the radial mesh, an appropriate radial mesh is built in the virtual space and the initial mapping is modified by taking into account the new radial mesh in the virtual space. To this end, an optimization technique using mesh refinement procedures is applied. The mapping combined with the mentioned deformation allows us to generate an unstructured polyhedral transition mesh (between the reservoir grid and the radial mesh) in the virtual space using the algorithm proposed in [1]. Finally, coming back to the real space, the obtained hybrid mesh may require a post processing step to recover the requested finite volume properties.