Morphology of Wax Crystals Affects the Rheological Properties and Thermal Conductivity of Waxy Oils

The rheological properties and thermal conductivity of waxy crude oils are critical factors influencing calculations for pipeline shutdown and restart procedures. In this study, the influence of wax content and PPD on wax precipitation characteristics, rheology, and the thermal conductivity of waxy oils is explored. The intricate mechanism through which the microscopic morphology of wax crystals affects the rheology and thermal conductivity is unveiled. The results indicate a significant correlation between the rheology and the thermal conductivity of the waxy oil. Both wax content and PPD play pivotal roles in determining the thermal conductivity and rheology of waxy oils by modulating the overlap of wax crystals and the effective solid phase content. Specifically, smaller crystal sizes coupled with a larger aspect ratio augment the intersection points between wax crystals and expand the solvation layer volume fraction. Consequently, this enhances the gel structure and viscosity of the waxy oil on one hand while broadening thermal conduction pathways and boosting the effective solid phase content on the other, ultimately elevating thermal conductivity. The study clarifies the mechanism underlying the correlation between rheological properties and thermal conductivity in waxy oils, offering significant insights into developing models of rheology and thermal conductivity during gelation.