Role of resins on wax deposition of waxy oils and its mechanism

Both resins and asphaltenes are major polar components in crude oils, with the resins less polar but much more in content. Previously, the influences of asphaltene concentration and polarity on wax deposition have been studied. However, the influences of resins on the wax deposition of waxy oils have received little attention. In this paper, we discuss the influences of resins on wax deposition based on experiments with waxy model oils containing 0.5–3.0 wt. % of resins, performed in a cold finger device. It was found that the addition of resins lowers the mass but increases the wax content of the deposits. N-alkane distributions of the deposits shift toward higher carbon numbers, and the critical carbon numbers slightly increase as the resin content in the oil increases. In addition, the resins are enriched into the deposits, which can be several times higher than those in the original bulk solution. Furthermore, resins can reduce the mechanical strength of the deposits, with the yield stress and gelation temperature of the wax deposits decreasing as the resin content increases. The change of waxy oil rheology caused by the existence of asphaltenes or resins is found to play an important role in the formation, aging of the deposits, and the enrichment of polar components in the wax deposition process.