Study of wax disappearance temperature using multi-solid thermodynamic model

• Main Authors: Mojtaba Mansourpoor, Reza Azin, Shahriar Osfouri, Amir Abbas Izadpanah
• Format: Article
• Language: English
• Published: SpringerOpen 2018-06-01
• Series: Journal of Petroleum Exploration and Production Technology
• Subjects: Wax deposition; Wax disappearance temperature; Multi-solid modeling; Viscometry method; Differential scanning calorimetry; PNA analysis
• Online Access: http://link.springer.com/article/10.1007/s13202-018-0480-1

Abstract Wax deposition inside pipeline and process equipment is a major problem in oil industry. In this study, a multi-solid thermodynamic model was developed to predict wax disappearance temperature (WDT). Paraffinic–naphthenic–aromatic (PNA) analysis was performed and two correlations were introduced for fusion properties of these species. In addition, WDT of 12 Iranian oil and condensate samples were measured using viscometry and differential scanning calorimetry (DSC) techniques. Experimental data of multi-component and ternary systems were utilized for validation of the model. It was observed that measured WDT by viscometry method is higher compared to DSC. Statistics analysis shows that DSC technique has lower average absolute relative error (AARE) and standard uncertainty compared to viscometry. Results show that the AARE of the model for ternary systems is 0.52% which is much lower among the previous developed thermodynamic models. In addition, AARE of the new model for 68 data was calculated about 0.23%, and R-square of model prediction was calculated about 0.97. The cumulative distribution function also indicates that P50 values are almost the same for model and experimental data. These results show that the model has a good accuracy. In addition, the accuracy of model increases as the average carbon number of oil mixtures increases. Finally, it was found that PNA analysis and distribution of each component in its sub-fractions have a considerable effect on the model accuracy.