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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.

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SynopsisA commercial lignosulfonate was modified by the addition of propylene oxide. The products obtained had a degree of propoxylation ranging from 19% to 49%. The modified lignosulfonates retained high solubility in water and high salinity tolerance, while their interfacial activity increased dramatically in comparison with the original lignosulfonate. Aqueous solutions of propoxylated lignosulfonates exhibited very low interfacial tensions (down to 10-'-10-* m N / m ) against both a pure hydrocarbon (isooctane) and a crude oil ( Lloydminster crude).