Surfactant development for enhanced oil recovery. Seventh quarterly report, July--September 1995

Aqueous dihexadecyldimethylammonium bromide (DHDAB) surfactant was used to form an emulsion with samples of crude oil (Burbank Crude Oil) supplied by Phillips Petroleum Company. Influence of the surfactant concentration in the uptake of the oil in the aqueous phase was studied. It was observed that as weight of the surfactant solubilized in the oil-water system increases the volume of oil solubilized in the aqueous phase increases. Viscosity of the emulsion was also observed to increase with an increase in the weight of surfactant added. A co-surfactant, n-butyl alcohol was added and its effect was to reverse the observation described above. The uptake of aqueous surfactant into the oil phase was very evident. Salinity scan of this system showed that the addition of sodium chloride, NaCl, produced a middle phase whose volume increased with an increase in the amount of salt added. Also there was observed, a remarkable high salinity tolerance. Rheology of the emulsion showed typical non-Newtonian behavior. The emulsion was observed to exhibit a pseudoplastic profile. The shear-thinning profile was evident from the observed viscosity-shear rate experiment