Effect of Emulsion Characteristics on Wax Deposition from Water-in-Waxy Crude Oil Emulsions under Static Cooling Conditions

Water-in-waxy crude oil emulsions with different water cuts were prepared with three different stirring speeds. The droplet size and distribution of the dispersed phase were determined by measuring the droplet diameter with trinocular biomicroscopy. The effects of the droplet size and distribution of the dispersed phase, water cut, and coldfinger temperature on wax deposition for water-in-waxy crude oil emulsions were studied experimentally using the coldfinger apparatus. The results show that the three influencial factors, including the coldfinger temperature, water cut, and droplet size and distribution, have a significant effect on wax deposition for the two-phase oil−water system. In addition, 24 test results referring to different test conditions have been analyzed statistically. The significance analyses of influencial factors have been accomplished by using the F-test method from the data obtained from variance analysis. The results show that, for water-in-waxy crude oil emulsion, the influence degree on wax deposition in order is the coldfinger temperature, water cut, and the droplet size and distribution. At the end of the experiments, the samples of wax deposits collected from the coldfinger experiments were analyzed using high-temperature gas chromatography (HTGC) to determine the percentage of iso-alkanes, n-alkanes, and total wax in the deposits. The results of this study provide a reference and an insight for the further study on the two-phase oil−water wax deposition in flow loop and actual pipelines and should be of significant interest to develop a reliable prediction model in the future.