Permeability Reduction Mechanisms Involved in In-Situ Gelation of a Polyacrylamide/ Chromium (VI)/Thiourea System

In this paper an investigation of the in-situ gelation of a polyacrylamide/chromium(VI)/thiourea system under flow conditions in unconsolidated sandpacks is presented. High flow resistance was observed in a localized section of the sandpacks that was consistent with deep-bed filtration mechanisms. A method to measure the size of aggregates in gel solution is also presented. Results from this method showed that the gel aggregates grow with reaction time and distance traveled through the sandpack, supporting the conclusion that filtration is a dominant factor in the in-situ gelation process under flow conditions.