Viscosity of Surfactant-Polymer Solutions

Abstract

Viscosity effects occurring in aqueous solutions containing a combination of surfactants, polymers and salts are of considerable interest in enhanced oil recovery operations. High molecular weight polymers, which are normally employed to improve sweep efficiency, lose much of their viscosity because of mechanical degradation and other adverse conditions in the reservoir. The mixing of the surfactant slug with the polymer slug in micellar flooding may lead to phase instability and low recovery efficiency. The formation of surfactant-polymer aggregates on the other hand, might have a positive effect on recovery. Such association complexes do not lose their viscosity permanently due to shear as they are quickly rebuilt upon cessation of shear forces. The present work shows that significant viscosity increases can be obtained by combining a petroleum sulfonate surfactant with a low molecular weight polyethylene oxide. For example, an addition of Carbowax®−20M to 4% Petrostep®−420 at 1.5% NaCl salinity first results in a viscosity increase with a maximum at about 0.2% of polymer. After this, the viscosity drops sharply reaching a minimum at 0.5% of polymer. Beyond this point, the viscosity begins to rise again at a rate which is somewhat higher than that observed for the polymer solution alone. The behavior observed with Carbowax®−6000 was similar although the increase in viscosity was smaller. No discernible effects were observed with Carbowax®−600. The magnitude of the viscosity increase observed at 0.2% of polymer was found to be strongly dependent on salinity.

Prominent processing techniques to manipulate semiconducting polymer microstructures

“…Instead, adding surfactants to such systems can cause an increase in the solubilization of polymer chains and thus, can lead to higher demixing temperatures. 450 Nonetheless, changes in polymer solubility are not surprising, as the use of surfactants was shown to affect the viscosity of polymer solutions 452,453 and to even induce solution-gel transitions. 454 Due to the existence of a plethora of surfactants, the spectrum of their interactions with various polymer chains in solutions is very broad.…”

Integrated Evaluation of Surfactant-Polymer Floods

“…The specific reservoir properties of salinity, temperature and crude oil composition are the major variables that affect the surfactant-polymer design (DeBons, et al, 2004). Viscosity effects occurring in aqueous solutions containing a combination of surfactants, polymers and salts are of considerable interest in enhanced oil recovery operations (Hornof, et al, 1983). High molecular weight polymers, which are normally employed to improve sweep efficiency, lose much of their viscosity because of mechanical degradation and other adverse conditions in the reservoir.…”

“…Polymer functions work by adding certain concentrations of water-soluble polymers to injection water to increase the injectant viscosity; surfactant functions work by adding certain concentrations of surfactants to injection water to reduce the interfacial tension (IFT) between the displacing and displaced phases. The polymer makes the displacing phase more closely match the viscosity of the in situ oil and thus achieves a more favorable mobility ratio (Hornof, et al 1983;Needham and Doe 1987;Maitin, 1992;Melo, et al, 2005). Surfactant-polymer flooding reduces the interfacial tension between the trapped crude oil and its associated brine.…”

A New Surfactant Flooding Model for Low Permeability Reservoirs

“…In China, the use of polymer in Daqing has already obtained a great success. Surfactant functions work by adding certain concentrations of surfactants to injection water to reduce the interfacial tension (IFT) between displacing and displaced phases [2,3]. Flow of the surfactant formulation through the reservoir allows the trapped oil droplets to deform and become mobile oil.…”