Dispersibility testing of artificial, blended oils - Gullfaks crude with different contents of wax and asphaltene added

The objectives of this activity in task 5 of the DIspersants on Weathered Oil-project (DIWO) were study how the content of asphaltenes and wax influenced on the chemical dispersibility of oil and on the droplet size of the dispersed oil. Oils with different content of wax and asphaltene were blended. Totally sixteen experiments were performed with oils with wax and asphaltene content of 0, 2.5, 5 and 10 wt%. A Gullfaks crude (150oC+) which has a low content of both wax and asphaltene was used as a basis oil. Wax and asphaltene were precipitated from Oseberg crude and added to the Gullfaks crude. The data were treated statistically by the Analysis of variance (ANOVA). The main conclusion from this project is that the wax content has a significant negative effect on the chemical dispersibility of the oil (increased wax content reduce the effectiveness). This is probably mainly caused by pour point problems which decrease dispersion. The asphaltene content seems to have no significant effect on the dispersion effectiveness. While the interaction effect between wax and asphaltene is significant and positive (a small addition of asphaltenes cancelled out the negative effect of high wax content). This is explained by the small addition of asphaltene probably prevents precipitation (crystal formation) of the waxes in the oil. The effect of the asphaltene contents on the droplet size of the dispersed oil is significant. The asphaltene content has a positive effect (increased asphaltene content caused larger droplets). This is probably caused by the increased density of the oil when asphaltene content is increased. 5 figs., 5 tabs., 6 refs