On Statoil’s Statfjord B platform, produced water was expanded from 60 to 6 bar (870 to 87 PSI) across a control valve. This pressure drop releases free gas into the system, which leads to a slug/plug flow regime in the downstream line, causing powerful pipe vibrations and unstable flare control – a problem for both safety and the environment.
Lack of deck space made a conventional separator impractical. Instead, a compact InLine separator was employed. Prior to installation, a full-scale 18” InLine DeGasser was extensively tested at an onshore facility. The InLine DeGasser has now been in continual operation since installation on the platform in September 2003. It’s been performing extremely well, with a stable flare system and no more vibration. The gas separated from the water is very dry and can easily be recompressed, delivering significant environmental tax savings.