PREDICTION OF FLUID DISTRIBUTION IN POROUS-MEDIA TREATED WITH FOAMED GEL

A wide variety of materials used to plug porous media, such as cross-l inked polymer gels, bacterial biomass, and foamed polymer gels, breakd own when exposed to excessive stress. However, models typically used t o evaluate the effect of these plugging agents neglect the breakdown p henomena and may not accurately assess the effect of a given treatment . Foamed gel is a very efficient, low-cost plugging agent that is part icularly susceptible to stress-induced breakdown. This paper demonstra tes the effect of breakdown on the performance of foamed gel profile m odification using a foamed gel breakdown network model. It is shown th at a simple analysis can be made using Darcy's law and a relationship between the applied pressure and the foamed gel barrier's permeability when the porous medium is comprised of noncommunicating layers of dif ferent permeability. Two types of successful treatments are identified , and they are distinguished by whether the foamed gel barrier in the low permeability zone breaks down at lower pressures (type 1) or highe r pressures (type 2) than the high permeability zone barrier. The rela tive length of the barriers in high and low permeability zones as well as factors that influence the gelled lens aspect ratio (permeability and gel saturation) govern whether a treatment is type 1 (low permeabi lity zone breaks down at lower pressures) or not. Under low injection pressures, all radial profile modification treatments have a higher po st-treatment flow redistribution ratio than linear treatments; under h igh injection pressures, only type 2 radial treatments have a higher R ow redistribution.