Characterization of Restart Pressure in Production Pipeline for Waxy Crude Oil as A Result of Injection of Non-Reacting Gas

Wax deposition within the walls of production pipeline of crude oil causes flow assurance issue due to reduction in flow rate. In the event of planned maintenance or an emergency shutdown due to bad weather condition, the crude oil will stop flowing in the pipeline, in which the temperature of the crude oil may drop below the Pour Point Temperature (PPT). As the crude oil is under a quiescent condition, wax crude oil may precipitate out of its liquid phase and becomes a wax-gel oil like substance, which may cause blockage in the pipeline. A high pumping pressure is needed in order to restart the pipeline and disintegrate the wax-oil gel. A recent study on gas voids in cured oil showed that the presence of gas voids within the pipeline could reduce the restart pressure needed to restart a crude oil production pipeline. It was anticipated that the volume of the gas voids could be increased through the injection of non-reacting gas in order to reduce the restart pressure needed. However, there was no previous attempt to study if the proposal would be practical in practice. The present study is aimed at studying the effects and effectiveness of gas bubbles intrusion through injection of external gas with respect to the restart pressure. A waxy crude oil flow loop was used in order to simulate the condition of a gelled waxy crude oil within the crude oil production line.