(383a) Modelling Ice and Wax Deposition in a Pipeline in the Arctic Environment

In the cold regions, such as Arctic environment, fluid temperature in pipeline can drop below the freezing point of water. Water even in trace amounts may form ice and lead to pipeline blockages and associated risks. The restart of the Poplar pipeline system which gathers crude oil from Montana and North Dakota was delayed due to a pipeline blockage that was caused by ice plug. The concern of ice formation in the Trans-Alyeska Pipeline System also leads the company to evaluate the ice risks to the pipeline. Ice can deposit on pipe wall In addition to wax deposition. . Solid formation on pipeline surface can lead to flow assurance and process safety issues, such as blockage of pipeline, pipeline component failure, and the release of hazardous liquid. The blockage of pipeline can cause additional burden or failure to pumping system. Remediating the plugging requires shutdown of pipeline operation, which cause tremendous cost and delay to the entire production system. Ice and wax deposition in pipeline is a slow process. Pigging operation can be used to remove the deposits on pipeline surface. However, if deposition is too thick, pipeline blockage can still occur. In order to prevent pipeline blockage, ice and wax deposition rates are required to be estimated.

This paper investigates ice and wax deposition rates in a 1.5 km pipeline under various operating conditions, such as inlet temperature, ambient temperature, and fluid properties. A fundamental model for both ice and wax deposition is proposed using first principles of heat and mass transfer. The interaction between water droplets (or ice particles) and wax is analysed and compared with experimental data.