An accurate and efficient reservoir modeling process is essential for developing and producing hydrocarbon reserves, especially from unconventional resources. In this paper, we address some of the main challenges associated with modeling complex reservoir geometry and heterogeneous reservoir properties. We present recently developed techniques for adaptively constrained 2.5D Voronoi grid generation and for generic global flow-based scale-up. Our novel gridding approach is based on a new constrained Delaunay triangulation algorithm and a rigorous procedure of constructing a Voronoi grid that conforms to piecewise linear constraints. These gridding approaches allow us to generate 2.5D Voronoi grids that precisely honor small faults, intersections of multiple faults, and intersections of faults at sharp angles, as well as adapt the grid cell sizes to a specified density function. By precisely representing geologic structures in our simulation grid and by accurately scaling up fine-scale geologic properties, we improve the consistency between our geologic descriptions and reservoir simulation models, leading to more accurate simulation results.
Numerical examples are provided to demonstrate the techniques and the advantages (both in efficiency and accuracy) of using adaptive gridding with global scale-up.