Stability of water-in-crude oil emulsions: Effect of cocamide diethanolamine (DEA) and Span83

Abstract

Water-in-oil emulsions are important in the petroleum industry in production operations, where the water content of the emulsion can be as high as 60% in volume. An environmentally friendly, nonionic emulsifying agent for crude oil emulsions Cocamide diethanolamine (Cocamide DEA) is introduced in the present work. The emulsion formation, rheology, stability and water separation performance of the DEA emulsifier was tested and compared with the commercially known Span83 non-ionic emulsifier. Water content (30, 40 and 50 vol.%), emulsifier molecular weight, emulsifier concentration (0.5, 1.0 and 1.5 vol.%) were the major variables investigated. The formulated emulsions viscosities and shear stress were measured at different operating temperatures (28 to 90°C) and different spindle rotation speeds (50 to 200). The experimental results showed that, for all the emulsion formed, the viscosity of the emulsion increases by increasing the water content and emulsifier concentration and decreases by increasing the rotation speed. The viscosity measurements were not constant with the spindle speed which confirms the non-Newtonian nature of the formulated emulsions. Finally, the experimental results showed that the emulsions formulated using the DEA emulsifier were more stable than the Span83 emulsions where the water separation time was longer and the water separation percentage was lower. Key words: Water in oil (w/o) emulsions, stability, surfactants, crude oil, diethanolamine (DEA).