Significant benefits could be realised through increased production from pipeline riser systems that currently exhibit severe slugging. This paper describes the dynamic modelling of severe slug flow and also mitigation methods for severe slug flow in pipeline systems.

A simulation of a pipeline riser system with a choke valve at the top of the riser was developed using the OLGA multiphase simulator. The working fluid for the system was a gas condensate. The mass flow into the system and the pressure were adjusted to induce severe slugging.

A choke valve was manually adjusted to determine the maximum opening it could have whilst stabilising the severe slugging regime. Once this critical opening was determined, the goal was to implement control which stabilised the severe slugging in the riser at a valve opening larger than this critical opening.

Feedback was applied to the system to attempt to mitigate severe slugging by controlling the pressure at a specific point in the pipeline. To achieve this, a pressure controller adjusted a control valve located at the top of the riser. It was found that a feedback loop which used the pressure at the base of the riser as the controlled variable could stabilise the severe slugging in the riser system at a maximum valve opening larger than the critical opening. It was also found that having the controlled variable as the riser base pressure resulted in the system stabilising four times faster than using the pipeline inlet pressure as the controlled variable.