Experimental and Mathematical Modeling of Wax Deposition and Propagation in Pipes Transporting Crude Oil

Abstract

One of the problems faced by the petroleum industry is the wax deposition in pipelines during transportation of waxy crude oil. Oil companies dealing with waxy crude often spend millions of dollars in remedial procedures. An ideal design should use an accurate mathematical model that would include all salient features of wax deposition and waxy crude transport to predict wax deposition during crude oil transportation. In this article, a comprehensive mathematical model, both in laminar and turbulent flow regimes, is developed. The model couples energy equation with deposition and removal kinetics model and thermodynamic model.

The k − ϵ turbulent flow model and energy equation were used to predict velocity and temperature distributions in the turbulent flow regime. Molecular diffusion of wax, as a mechanism of deposition and sloughing effect due to the hydrodynamic forces of fluid on deposited wax, have been considered. Parametric studies on the variation of the amount of wax deposition were performed for a mixture of toluene and oil wax cut in an experimental setup. Overall predictive ability of the proposed model is excellent for the laminar flow. For the turbulent flow regime, no necessary complete experimental data for model were available. Consequently, qualitative results were presented and discussed.

Keywords:

• numerical modeling
• pipeline
• turbulent and laminar flow
• wax deposition