Demulsification Kinetics of Water-in-Oil Emulsions of Ecuadorian Crude Oil: Influence of Temperature and Salinity

This work focuses on the stability analysis of water-in-oil macroemulsions with a crude oil from Sacha Field in Ecuador. This field is an important hydrocarbon resource in Ecuador with typical bottom water drive. The comprehensive stability analysis includes coalescence, water resolution or phase separation, water-oil interfacial tension and interfacial dilatational viscoelastic modulus measurements over time. Two main parameters were controlled in these experiments: water salinity and temperature. This analysis, reported here for the first time for this important resource in Ecuador, sheds light on which mechanisms are likely to control the stability of these macroemulsions. Our results indicate that regardless of temperature, lower salinity favors emulsion stability, likely due to the tendency of a stiffer interface to form at low ionic strength, as interfacial viscoelasticity results show. On the other hand, higher temperatures favor water resolution, possibly due to higher sedimentation rates, which is further favored at higher salinity. Finally, analysis of the interface buildup rates could explain the observed increased in emulsion stability over time.