Rate-dependent polymer adsorption in porous media

• Rate-dependent polymer adsorption in porous media was investigated.
• The double-polymer bank dynamic method was used.
• Results showed that as flow rate increased, polymer adsorption increased.
• Adsorption was largely reversible with minimal incremental irreversible adsorption.
• Inaccessible pore volume decreased with increase in flow rate.

Laboratory core flood experiments were conducted at different flow rates with partially hydrolysed polyacrylamide (HPAM) oilfield Enhanced Oil Recovery (EOR) polymer and silica sand to investigate the polymer retention in porous media due to flow rate variation. Specifically, the double-polymer bank method was used in a new way to quantify and understand total incremental retention (both reversible and irreversible) induced by flow rate variation for HPAM polymers. Experimental results indicate that adsorption was the dominant retention mechanism. Further, the results obtained show that polymer adsorption was rate-dependent (i.e., as flow rate increased, adsorption increased), and that the adsorption was largely reversible with minimal incremental irreversible adsorption. It was also observed that flow rate impacted polymer inaccessible pore volume (IAPV) decreasing from 32% to 15% as flow rate increased from 0.8 ml/min to 6.0 ml/min. Finally, results from the study also give better insight into understanding HPAM flow-induced adsorption and their effect on permeability reduction processes.