Use of mixed surfactants to improve the transient interfacial tension behaviour of heavy oil/alkaline systems

Abstract

Abstract The objective of this study was to identify suitable combinations of additives to aqueous alkaline formulations for the potential recovery of Saskatchewan heavy crude oil. A previously developed strategy was applied to screen various additive combinations consisting of three commercial petroleum sulfonate surfactants and two commercial lignosulfonate surfactants. The selection of the additives was based on a large number of physical and interfacial property measurements in conjunction with phase stability tests at different temperatures. The resulting ternary formulations, labelled here as Mixed‐Surfactant‐Enhanced Alkaline (MSEA) systems, were very successful in reversing the trend of increasing interfacial tension with time that characterizes additive‐free alkaline/crude oil systems. This success came at the expense of initial IFT values that were considerably higher than those exhibited by the corresponding additive‐free alkaline solutions. However, at higher temperatures (65 °C), these ternary MSEA formulations were capable of generating very low IFT values against the crude oil (in the range of 5 × 10 −2 to 10 −1 mN/m), which suggests that they could be suitable candidates for commercial exploitation of heavy oil recovery processes.