Stability of oil-in-water emulsions by SDS compound

Abstract

Surfactants are often required to reduce emulsion viscosity and heavy-oil flow resistance in pipelines, thereby forming a stable oil-in-water emulsion under shear stress. This study aimed to quantitatively discuss and analyze the stability of oil-in-water emulsions and characterize them through the initial viscosity change rate K. The value of K was obtained based on the oil-rich-phase viscosity curves of oil-in-water emulsions comprising sodium dodecyl sulfate (SDS), heavy oil, and water at different time points. Results showed that a smaller K corresponded to a more stable emulsion according to analysis of the effect of the compound system on emulsion stability and the synergistic mechanism. We then combined with 1-pentanol and octyldecyl glucoside (APG0810) with SDS. Results showed that the K values of the emulsions decreased from 19.457 to 6.284, and 19.457 to 5.834, respectively, after mixing 6% 1-pentanol and 0.4% APG, respectively, with 0.14% SDS. Then, 0.14% SDS was compared with 1.2% a mass fraction of each of the three additives to form a compound system, and the K values were found to follow the trend K_{1-pentanol/SDS} > K_APG/SDS. Thus, the stability of APG/SDS oil-in-water emulsion was better than that of 1-pentanol/SDS emulsion.