Water-in-crude oil emulsions in the Burgan oilfield: Effects of oil aromaticity, resins to asphaltenes content (R/(R+A)), and water pH

Asphaltenes and resins separated from emulsion samples collected from Burgan oil field were used with heptane-toluene mixtures as model oil to study the effect of oil aromaticity, resin content, and pH of the aqueous phase on the stability of water in model emulsions. It was confirmed that, as long as the asphaltenes are completely solubilized, increasing aromaticity leads to less stable emulsions. A consistent correlation between emulsion stability and relative resin mass content (R/(R+A)) was observed for all three of the field samples. There was a sharp decrease in stability when the R/(R+A) value exceeded 0.75. Emulsion stability was enhanced at high pH and possibly at very low pH (<2).