Flow of oil drops through straight and constricted microchannels

Abstract

A dominant mechanism for oil trapping in porous media is the snap-off, defined as the disconnection of a continuous flow of fluid as it passes through canyons and pore constrictions satisfying a criterion based on capillary pressure imbalance. In this paper is investigated the dynamic of an oil drop immersed in water flowing through a microchannel formed by two parallel plates. To understand the effect of the geometry on microflow, a second configuration formed by two parallel plates with a throttling, is also used. The twodimensional, transient, incompressible, Newtonian, two-phase flow considered here, represents in simplified form, which occurs in the oil reservoir on the microscopic scale during mobilization of the oil droplets formed
by the snap-off mechanism. The numerical solution of the problem with liquid-liquid interface is obtained by Volume of Fluid (VOF) approach. The results, although qualitative, are extremely encouraging and show that the dynamics of the motion of the oil drop in the geometries is controlled by capillarity number, viscosity ratio and geometrical parameters. The oil drop deforms to a greater or lesser degree in response to the dominant forces. The presence of the constriction significantly increases the pressure field as also the flow velocity of the droplet in the throat.