Wax deposition from Middle East crudes

This paper reports measurements of wax content by acetone precipitation tec hniques as well as wax appearance temperature (WAT) by viscosity measuremen ts and differential scanning calorimetry (DSC) of eight different stock-tan k crude oils from the Middle East. Comparison of WAT measured by DSC and vi scosity indicates that the viscosity method overestimates the WAT. Crude oi l gravity measured, by digital density meter, and molecular weight, by vapo r pressure osmometer, were used to characterize the plus fraction and predi ct WAT and amount of wax formed at a given condition by the thermodynamic m odel. 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 a nd that predicted by the thermodynamic model are in good agreement. (C) 200 0 Elsevier Science Ltd. All rights reserved.