Modelling of Paraffin Wax in Oil Pipelines

Abstract

As warm oil or condensate from the reservoir flow through a pipeline on the cold sea bottom, wax often precipitate and deposit on the wall. To predict the rate of the deposition, wax modeling is important. The main mechanism contributing to deposition, molecular diffusion, is driven by a radial concentration gradient. The concentration gradient is driven by the radial temperature gradient. When precipitation of wax crystallites occurs in the bulk of the flow, it affects the concentration gradient, which again affects the rate of deposition. The current thesis gives an elucidation of this particularity. Fundamental heat and mass transport equations are solved numerically in Matlab and the result shows that the concentration profiles become slighter as the precipitation become larger. This decreases the mass flux due to molecular diffusion. A term “shear dispersion” was introduced in 1980’s to describe particle deposition of wax. The term has been used in several wax deposition models, but the mechanisms behind are not well explained in the literature. An elucidation of both a shear induced lift force and shear induced diffusion are investigated.