Upscaling of Water-Flooding Scenarios and Modeling of Polymer Flow

Abstract

This thesis considers simulations of the fluid flow in petroleum reservoirs, and includes work on upscaling methods and on modeling of polymer flood- ing, which is a particular method of enhanced oil recovery. The details of a small-scale model can have large impact on the flow on larger scales, and upscaling is therefore an essential part of reservoir modeling. We consider upscaling on the field-scale, investigate the balance of forces during the water-ooding of a reservoir, and use this to asses the applicability of different upscaling methods, and in particular steady- state methods. Two novel upscaling methods based on the steady-state assumption are suggested, and a comparison study is performed between different methods through realistic field-scale simulations. Established two-phase upscaling techniques are also extended to include polymer properties. As an alternative to upscaling, we also consider the application of a multiscale method to run polymer flooding simulations more efficiently. Using the developed solver, we demonstrate that we are able to obtain fast and accurate solutions on complex grids, using realistic and highly non-linear ow physics. Considering another aspect of polymer modeling, we address a known issue with the mathematical model of an import physical effect of polymer flooding, the velocity enhancement due to inaccessible pore volume. The conventional model may lead to ill-posed equations, and we propose alternative formulations to obtain numerically more stable simulations.