An experimental study of the in situ gelation of a polyacrylamide-chromium acetate system in a polymer-treated porous medium

The application of polymer-metal ion gel systems has been effective in improving sweep efficiency and increasing crude oil production. The use of a polyacrylamide-chromium acetate gel system involves the injection of a gelant solution that contains a high molecular weight polymer and a crosslinker which is a multivalent metal ion. The performance of this system is limited by short gel times that make in-depth gel treatment impossible. In previous studies it was found that an important mechanism responsible for in situ gelation, which is indicated by a rapid flow resistance build up, is filtration of pre-gel aggregates. It was hypothesized that the interaction between previously adsorbed polymer and flowing aggregates partly contributes to the filtration of pre-gel aggregates.; The objective of this research was to test the reactivity of previously adsorbed polymer and its effect on the build up of flow resistance when a gel solution flows thorough a porous medium which is pre-treated with a less reactive polymer. By this pretreatment the adsorption sites of the porous medium would be satisfied and the interaction between adsorbed polymer and flowing gel solution would be reduced. (Abstract shortened by UMI.)...