The continuous demand for oil and gas forces the petroleum industry to develop new and cost-efficient technologies in order to increase recovery and exploit existing fields. Subsea wet gas compression of the unprocessed well stream is a powerful tool in increasing production capacity and utilizing remote regions.
Wet gas compressors are particularly useful for handling gas-dominated multiphase flows. Although a limited amount of research has been done on the field, previous studies have revealed that the liquid phase has considerable impact on the compressor performance, from both a fluid mechanical and a thermodynamic perspective.
Being able to ensure stable and predictable compressor behavior in subsea installations is challenging. As the reservoir pressure drops during production, the compressor enters a region where it is far more susceptible to inlet slugging. Inlet slugging may lead to internal compressor damage, including damage to seals, bearings and compressor blades. It needs to be stressed that a slug in this context does not entail 100% liquid holdup upfront of the compressor, but a substantial increase of liquid content in a gas dominated multiphase flow.
An experimental investigation has been carried out on an advanced wet gas test rig, consisting of a shrouded centrifugal impeller, a vaneless diffuser and a circular volute. The paper explores the possibilities of creating realistic inlet slugging scenarios and documents its impact on the compressor system. Slugging was introduced either by collection of liquid in a negatively sloped inlet pipe (i.e. terrain slug simulation) or by sudden opening of an inlet liquid valve upstream of a symmetrical injection manifold, so to create a more “homogenous” slug. The compressor ability to handle such slugs is analyzed. Furthermore, the drive capability to respond to sudden changes in torque requirement is documented. The experimental results form a basis for future dynamic simulation.