Further Insights into the Mechanism of Disproportionate Permeability Reduction

Disproportionate permeability reduction (DPR) refers to the phenomenon where polymer solutions and gels reduce permeability to water more than to oil/gas. This study investigates DPR mechanisms via core- and micro-model-scale experiments using Cr(III)-acetate-HPAM gels. Core-scale NMR detected changes in trapped/free water during oil and water flooding, while micro-model tests recorded oil/gas invasion behavior visually. Results show that gel-displacement initiates oil flow paths, followed by gel dehydration under pressure gradients. During water flooding, gel rehydration blocks channels, significantly reducing water permeability. Mechanisms contributing to DPR include channel segregation, gel rehydration, residual oil effects, and gel’s intrinsic low permeability to water.