The Effect Of Resin And Asphaltene Interactions On The Rheological Behaviors Of Waxy Oils

Wax crystals start to precipitate due to supersaturation when the temperature of waxy oil is lower than the wax appearance point.When the precipitated wax crystals reach a certain amount,a three-dimensional mesh structure will be formed to wrap the liquid oil,and the waxy oil system will change from liquid state to gelatinous state and show complex rheological behavior.In addition to wax,resins and asphaltenes are also major components of the waxy oils,which have an important influence on the rheological behavior of the waxy oils because they can interact with wax molecules and change the wax-precipitation properties.The influence of resin and asphaltene on the rheology of the waxy oil is usually investigated by formulating a simulated oil containing only resin or only asphaltene,and the influence of the interaction between resin and asphaltene on the rheology of the waxy oil cannot be investigated.This paper first investigates the effect of the interaction between resins and asphaltenes on the rheology of waxy oils when they are co-present in the waxy oils.The analysis of the experimental results of the gelling properties and viscosity of the six waxy oils showed that the waxy oils containing both resin and asphaltene had lower gelling temperatures and smaller yield stresses than those containing only resin or only asphaltene,indicating that the interaction between resin and asphaltene would result in a weaker gelling structure and lower viscosity of the waxy oils.By formulating waxy oils with different concentrations of asphaltenes(0%,0.02%,0.05%,0.1%,0.12%,0.12%)at a certain resin content(0.2%,0.5%,1%,3%,5%),it is clear that the stronger the interaction between resins and asphaltenes,the weaker the gelling structure of the waxy oil.It shows that the waxy oil has lower gelling temperature and smaller yield stress with increasing asphaltene concentration at a certain resin content in the waxy oil.The viscosity of the waxy oil also decreases with the enhancement of the interaction between resin and asphaltene.The effects of resin and asphaltene on the microstructure of wax crystals were analyzed by microscopic observation and XRD tests.It was found that when the waxy oil contains both resin and asphaltene,the interaction of the two will cause the wax crystals in the waxy oil to agglomerate into clusters and the crystalline surface spacing of the wax crystals is larger.The interaction between resins and asphaltenes causes changes in the wax crystal morphology and crystal structure of the waxy oil,resulting in differences in the rheology of the waxy oil.