Rheological behavior of heavy crude oil and its emulsions

The rheological behavior and start-up characteristic of heavy oil emulsions for shutdown pipeline have been studied. To illustrate the properties, we examined the relationship between start-up stress and apparent viscosity. The oil-water ratio, surfactant concentration, start-up temperature and constant shear rates on start-up maximum stress were investigated and a new start-up pressure model was established. The results indicate that start-up stress and apparent viscosity have a consistent change with time. Equilibrium shear stress could be used to predict start-up pressures. The calculated values were in good agreement with experiment ones, which the absolute relative error is less than 10.0%.