Finite Element Simulation of Multiphase Flow in Oil Reservoirs -Comsol Multiphysics as Fast Prototyping Tool in Reservoir Simulation

Abstract

Reservoir simulation is a powerful tool to mimic the formation behaviour during primary production and later on for planning enhanced oil recovery (EOR) pattern. However, all available commercial and developed scien-tific/academic software for this purpose is based on either finite difference method (FDM) or finite volume method (FVM). Recently finite element method started to gain more attention in the scientific and commercial practices due to its robust results and the ability to deal with complex boundaries. COMSOL Multiphysics is a finite element method (FEM)-based software, having very special features, which are different from standard reservoir engineering software packages like Eclipse or CMG, which are black box-type software. The most important feature of the COMSOL is that user can see equation and modify it - customize for specific conditions and objectives, as well as couple different physics together and apply different solvers, which are under user’s disposal. In this paper, short background of FEM will be illustrated and then the mathematical models of two-phase immiscible flow of water and heavy oil will be reviewed and simulated using COMSOL Multiphysics on the famous inverted five-spot model. The comparison between the results of Comsol Multiphysics and Eclipse shows good agreement. This study is the first step in applying Comsol Multiphysics to reservoir simulation. Further steps will involve simulating thermal enhanced oil recovery using steam flooding technique and coupling Comsol Multiphysics with CMG software package to enhance simulation inputs and outputs.

Keywords

• oil reservoir simulation
• enhanced oil recovery methods
• finite element method
• comsol multiphysics
• mathematical models of two-phase immiscible flow of water and heavy oil