Core (Oil and Gas) Ltd

Stability and Slug Mitigation and Suppression

Once adequate uptime has been achieved, Operations personnel generally rank stability of the process as the next objective.

Production declines from mature assets have been supplemented in many cases by third party production, usually from a subsea tie back. A combination of well, terrain and riser based slugging is usually a major challenge for most assets as this unstable feed is invariably a cause of topside instability.

The impact of slugging differs greatly from asset to asset and Core personnel have extensive experience of improving topsides stability thus ensuring production is maximised. The slugging encountered on most assets (and wave instability on FPSO's) is not a major problem and the effect can be handled within the surge volume of the separator or by minor adjustments to the compressor capacity. Improved produced water quality, zero flaring and stable oil/condensate export flowrates can usually be achieved.

However as the magnitude of the slugs increase, the impact on the topsides stability is more severe and further intervention is required. This requires a slug suppression technique to be adopted to regulate the flow through the riser. This type of system is complex to optimise and if not designed or setup correctly, dramatically increases instability in the multiphase pipeline, increases topside instability and therefore production deferral. Core personnel have significant experience of these systems and the costs versus benefits/risks of their use.