Effects of Gelant Composition and Pressure Gradients of Water and Oil on Disproportionate Permeability Reduction of Sandpacks Treated With Polyacrylamide-Chromium Acetate Gels

Abstract

Summary For some polymer gels applied in reservoirs to control water flow, a favorable disproportionate permeability reduction (DPR) occurs in which permeability to water is reduced to a much greater extent than it is to oil. Permeability reduction in sandpacks by partially hydrolyzed polyacrylamide-chromium acetate gels was studied as a function of gel composition and the pressure gradients imposed on the gels. For the range of parameters studied, increased gel composition increased the factors by which the permeabilities to water and oil were reduced. Increased gel composition also increased selectivity, a measure of the water-permeability reduction with respect to oil-permeability reduction. Applied pressure gradients during steady-state flows had little effect on oil permeability and a moderate effect on water permeability. Material balances on phases and components in the sandpacks provided insights into mechanisms responsible for the development of flow channels through gelled sandpacks and mechanisms contributing to favorable DPR. Increased pressure gradient during channel development decreased the selectivity of the treatment.