An experimental design approach investigating the effects of operating variables on the viscosity of heavy crude oil-in-water emulsions using lecithin as a natural surfactant

This work investigates the effects of the addition of biosurfactant (lecithin) for the reduction of heavy crude-oil viscosity. Response surface methodology was employed to study the effect of three experimental factors: temperature, water to oil ratio (WOR) and emulsifier concentration (EC). All factors were found to have a high significant effect on the viscosity of the heavy crude oil. The interaction between temperature and WOR had more impact compared to that between WOR and EC. Yet the interaction between temperature and EC was not significant. Moreover, lecithin concentration seemed to have more effect on the viscosity reduction at low WOR. A model was developed for the viscosity with respect to the investigated factors and proved its goodness of fit with R-2 of 96.03% at 95% confidence level. A good agreement between predicted and experimental values was achieved. The optimum conditions for achieving a targeted viscosity value based on industrial recommendations were determined and experimentally verified.