Wax deposition from Middle East crudes

This paper reports measurements of wax content by acetone precipitation techniques as well as wax appearance temperature (WAT) by viscosity measurements and differential scanning calorimetry (DSC) of eight different stock-tank crude oils from the Middle East. Comparison of WAT measured by DSC and viscosity indicates that the viscosity method overestimates the WAT. Crude oil gravity measured, by digital density meter, and molecular weight, by vapor pressure osmometer, were used to characterize the plus fraction and predict WAT and amount of wax formed at a given condition by the thermodynamic model. Comparison between predicted and measured results shows that measured WAT by DSC compares very well with that predicted from the model for most crudes. Generally, wax contents measured by the modified UOP method 46-64 and that predicted by the thermodynamic model are in good agreement.