Lin, M., Xu, X., Lv, J. et al. Pet. Sci. (2011) 8: 93. doi:10.1007/s12182-011-0120-6
The oil/water interfacial properties of crude oil emulsions formed by alkaline/surfactant/polymer (ASP) flooding in the Daqing Oilfield were investigated in this paper by the measurement of interfacial tension, interfacial shear viscosity and Zeta potential of the oil/water system. The result showed that both NaOH and Na2CO3 could react with acid substances in the crude oil to produce interfacially active components, which are adsorbed on the interfaces between the aqueous phase and oil phase, resulting in a decrease of the interfacial tension, negatively charging the surface of oil droplets, but making little change in the interfacial shear viscosity. For the same ionic strength of NaOH and Na2CO3, the interfacial tension of NaOH solution-crude oil system is lower, but the interfacial shear viscosity of NaOH solution-crude oil system is higher, than that of Na2CO3 solution-crude oil system. The negative value of the Zeta potential on the surface of the oil droplets is large. Accordingly, the O/W emulsion of NaOH solution-crude oil system is more stable than that of Na2CO3 solution-crude oil system.