Lab simulation of profile modification and enhanced oil recovery with a quaternary ammonium cationic polymer

Long-term water flooding in oilfield exploitation generally results in a marked increase of interlayer and/or inner-layer heterogeneity of oil reservoirs and premature polymer production in large quantities from flooding reservoirs. This paper presents a novel quaternary ammonium cationic polymer (NCP), which was prepared by using maize starch and (2,3-epoxypropyl)trimethylammonium chloride as raw materials. The effect of NCP on water plugging and profile modificaton after polymer HPAM (partially hydrolyzed polyacrylamide) flooding was evaluated by laboratory simulation tests of enhanced oil recovery. The experimental results indicate that crosslinking gel system formed after HPAM-NCP alternate injection could effectively seal off the high permeability zone to force the successive liquid to flow to mid-low permeability zones and get profile control in depth. In addition, the contact angle measurements reveal that the adsorption of NCP on the montmorillonite changed its surface wettability and enhanced its hydrophilicity, which promoted enhance oil recovery significantly.