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

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.

Effect of Added Surfactants on the Dynamic Interfacial Tension Behaviour of Alkaline/Diluted Heavy Crude Oil System

“…This behaviour could be due to the role of micelles on the oil transfer. Similar observations were made by Chiwetelu et al [17] for mixed surfactant enhanced alkaline/heavy crude oil. However in their case, the initial IFT values were considerably higher than those exhibited by the surfactant free system.…”

Studies of Synergism/Antagonism for Lowering Dynamic Interfacial Tensions in Surfactant/Alkali/Acidic Oil Systems

“…Rudin et al (21) suggested that the dominant mechanism by which added surfactant aids in the reduction of IFT was the formation of mixed micelles with the ionized acid. Chiwetelu et al (22) reported that the addition of mixtures of surfactants to NaOH solutions successfully reversed the undesirable trend of increasing IFT with time. Chatterjee et al (23) found that there existed an optimal pH which produces ultralow IFT in alkali/acidic oil systems.…”

Studies of Synergism/Antagonism for Lowering Dynamic Interfacial Tensions in Surfactant/Alkali/Acidic Oil Systems, Part 2: Synergism/Antagonism in Binary Surfactant Mixtures

“…Surfactant mixtures have been used in enhanced oil recovery processes to produce ultra-low interfacial tension (1,2) or curb undesired behavior such as adsorption (3).…”