Temperature Profile and Its Effects on the Location of Lower Denser Substance in Waxy Crude Oil: A Numerical Study

When waxy crude oil is undergoing cooling and becomes a gel predicting an accurate restart pressure is a challenge. For simplicity, waxy crude oil was assumed as a single phase incompressible fluid in the conventional restart pressure equation, which was found to result in over-predicted restart pressure and subsequently overdesigned pipeline systems. Previous research found that there is formation of void in waxy crude oil under dynamic and static cooling, and this has an impact on the gelled crude oil structure and in the magnitude of restart pressure. It was also reported that the voids volume near the pipe wall was higher than that formed around core of the pipeline. This study is, therefore, aimed at analysing profiles of temperature across the pipeline and its effects on the location of lower denser substances in waxy crude oil. ANSYS-CFX workbench was used to develop the model and analyse the profiles of temperature in different location of the pipeline. Methane of 10% (average) in waxy crude oil was included in the model to replicate multiphase and observe the temperature effects on the gas locations across the pipeline. This study observed a decreased temperature gradient towards wall of the pipeline. It can be concluded that the higher voids volume at the wall than core in the previous study is mainly due to the lower temperature at the wall of the pipeline, and this can also be referred from the results presented.