On the Modeling of Viscous Oil-Water Immiscible Displacements

ABSTRACT

It is well known that microscopic phenomena occurring during flow through porous media play an important role on macroscopic properties, such as residual oil saturation and relative permeability curves. Laboratory experiments involving micro-models and cores allow an evaluation of such microscopic phenomena, however these experiments are usually costly and time consuming. An effective alternative for the investigation of flow at the pore scale is through the use of numerical models, which allows sensitivity on several parameters in a timely and cost efficient manner.
Results from numerical experiments performed on a digitized porous media involving single and two-phase flow of heavy oil and water at the pore-scale are presented. Two and three dimensional porous media patterns are constructed from packing grains or spheres of a given particle size distribution, generating a flow domain of the order of microns. Single phase flow is performed in order to obtain absolute permeability by solving pore-scale equations using a finite volume numerical approach. Averaging of pressure and velocity fields allows the determination of absolute permeability in different directions, thus providing an indication of permeability anisotropy.
After the medium is fully saturated with water, viscous oil displaces following a drainage mechanism by using the Volume of Fluid method for interface capturing. Oil viscosity varies from 1 to 100 mPa.s. The typical drainage displacement mechanisms and the effects of viscosity on fluid distribution are observed. The irreducible water saturation and the initial oil saturation are mapped. The individual phase properties are calculated.

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