Experimental Investigation of the Effect of Viscoelasticity on Enhanced Oil Recovery during Polymer Flooding

Polymer flooding, which is a promising chemical enhanced oil recovery (EOR) method, leads to more efficient extraction of oil from depleted reservoirs and has proven technical and economic success in various projects where oil recovery often increases considerably. During polymer flooding, viscosity helped to maintain a favorable mobility ratio. Through increased water phase viscosity and improved sweep efficiency, polymer solutions improved oil recovery. Viscoelastic polymers can improve oil recovery beyond that of inelastic polymers by mobilizing the residual oil and increasing the microscopic displacement efficiency. These polymers can mobilize oil entrapped in porous media due to high capillary forces, rock configuration, or rock attraction by stripping, dragging, and pulling oil molecules into pore channels. In the present study, the effect of the two polymers on oil recovery and breakthrough was determined by selecting polymer concentrations to maintain similar viscosities with different viscoelastic behaviors. A rheological approach for the determination of storage, loss modulus, and relaxation modulus was adopted to determine the difference in the elastic behavior of the HPAM-2625 and carboxymethyl cellulose (CMC) polymers. At the concentrations used for the investigation, it was discovered experimentally that the CMC polymer was more elastic than HPAM-2625. A higher oil recovery due to viscoelasticity was achieved in the flooding experiment. An approximately 4.9% higher recovery was observed for a higher viscoelastic candidate, the CMC polymer. This article focused on the impact of viscoelasticity on oil recovery during polymer flooding. The results of this study can be useful for guiding polymer screening, design, and optimization for flooding in oil fields.