Simulating wax deposition in pipelines for flow assurance

A method is presented for simulating wax deposition in pipelines in which the wax phase is represented as a continuous distribution of n-paraffin components. The thermodynamic properties of the wax are predicted using a previously developed thermodynamic model. We have adopted a mass transfer model to predict the likely rate of wax deposition. Predictions from the model are compared with observations of flow-loop experiments, and predictions for full-scale pipelines are presented. The impact of the removal of deposited wax by shearing is also investigated. We demonstrate the effect of assuming molecular diffusion to be the dominant mechanism of wax deposition, and we also show that not representing the wax with its full n-paraffin distribution leads to serious distortions of the pipeline simulations. Practical software development issues in the implementation of the model are outlined.