Abstract
Computing well performance accurately is very important for reservoir management and optimization. Standard large-scale reservoir simulators, however, are not able to resolve detailed near-well physics such as the interaction between the local pressure gradient, reservoir heterogeneity, and well completion. This is because these effects occur on scales that are very small compared to typical simulation grid blocks. In this work, we describe a modeling procedure for representing the well and near-well region that is able to resolve flow down to the scale of the completion and perforations. Our computations involve single-phase flow simulations on unstructured 3D tetrahedral grids. The Darcy-Forchheimer equation is solved in order to include non-Darcy effects, which can be important in the near-well region where fluid velocities are high. The new modeling capability is applied to quantify the impact of completion type – open hole or perforated cased hole – on well productivity. Next, in order to capture these detailed effects in large-scale simulation models, a new upscaling procedure is developed and applied. The approach can be categorized as a local-global upscaling method which uses global coarse-scale simulations to provide key parameters for the local upscaling computations. An example for a case with significant non-Darcy effects demonstrates the high degree of accuracy achievable using this technique.
