Numerical Analysis of Polymer Micro-model Flooding Experiments

Abstract

Adding polymers to the injection water leads to an increase in water viscosity together with a reduction in water permeability. As a result, the mobility ratio improves leading to a more efficient displacement process and a higher oil recovery factor. Different physical and chemical processes accompany the flow of aqueous polymer solutions in porous media resulting in the loss of polymer solution viscosity. The numerical simulation of polymer EOR in porous media relies on mathematical models that have already been proposed in literature. However, direct comparison between numerical simulations and experimental data from flood experiments is limited. Although important parameters can be obtained from core experiments, the local distribution of static and dynamic fluid transport parameters remains largely unknown. 2D micromodels such as silicon edged pore networks are an alternative as they provide visual access to the flooding process and enable a detailed quantification of the local distribution of relevant transport parameters. In this paper, a micromodel simulator that considers polymer related physical and chemical effects such as non-Newtonian rheology of the displacing phase, permeability reduction, retention and salinity effects is presented using comprehensive mathematical models. For the solution of transport system equations the software Matlab^® by MathWorks, Inc. is used as it provides a flexible framework for implementing the underlying transport and auxiliary equations. A pattern generator code is used to define the 2D micromodel structure, generating predefined porosity and permeability averages with local heterogeneities. These generated patterns lead to the micromodels used in this work.

Results obtained from micromodel flooding experiments will be compared to results from numerical simulation in order to test the ability of existing mathematical models to reproduce dominating physico-chemical effects.

The work aims to provide and support selection criteria for optimizing polymer EOR by predicting polymer performance for a variety of critical input parameters such as polymer selection, polymer concentration, salinity and target viscosity for various average reservoir qualities (k, φ).