We evaluate the risk formation of wax deposit along a transnational crude transport line, running for almost 500 km between the south of France and the Alps, feeding two refineries of Feyzin (Rhône area), and Cressier (Switzerland). As occurred in the recent past, the presence of even a thin deposit of wax along the pipe wall during a pig inspection, may hinder the acquisition of data and images concerning the integrity of the pipeline. As inspections are regularly carried out to ensure the safety of operations and integrity of the facilities, it is therefore particularly relevant to be able to minimize the potential formation of wax sediments, especially after cleaning the pipeline, e.g., through a scraping pig, and before the smart pig run.
In this paper we evaluate quantitatively the formation of wax deposit determined by different crudes and blends. Through a qualitative correlation between predicted deposit thickness with crudes’ physical properties, such as wax content, wax appearance temperature, viscosity etc., operators can elaborate a screening process to guide their choice of crudes to run in the period following the cleaning of the pipeline and before the inspection, therefore minimizing the risk of deposit formation.
Through a quantitative prediction of the wax deposit thickness, we also provide useful general information concerning the total wax expected to deposit over long periods of time, therefore reducing the risk that an excessive wax deposit may eventually obstruct the pig run, requiring the temporary shutdown of the pipeline for maintenance.