Concentration profiles of reactant in a viscous finger formed during the interfacially reactive immiscible displacements in porous media

A simple unsteady-state convective-diffusion model was employed to simulate reactant concentration profiles in a viscous finger, which is created duri ng interfacially reactive displacement of two immiscible fluids in porous m edia. A two-dimensional system was considered. It was assumed that the fing er grew in one direction at a constant flow rate and that a fast chemical r eaction was taking place at the oil-water interface layer. Interaction with reservoir rock was also taken into account. Two types of convective flow w ere studied: steady-state laminar flow with a parabolic velocity profile an d plug flow with a flat velocity profile. The numerical method of lines was used to solve the model equation. A significant decrease of reactant conce ntration in the water phase, especially in the fingertip area was observed. This can cause important changes in interfacial behavior and influence the efficiency of fluid displacement. The model numerically confirmed previous visual observations of displacing patterns during the displacement of acid ified oil by alkaline solutions. (C) 2000 Elsevier Science B.V. All rights reserved.