In the current brown field environment a lot of mature gas wells in the Southern North Sea (SNS) are liquid loading. Foamer can be injected in the wellbore as a gas well deliquification (GWD) measure to mitigate this liquid loading behavior. Foamer can be injected periodically in batch mode or continuously downhole by means of a small capillary string installed in the wellbore.

To date ONEgas* is producing 12 offshore gas wells located on 3 manned SNS platforms by means of continuous foamer (CF) injection. The first offshore CF installation came online in 2011 and dozens more installations are scheduled in the near future. CF has gone through a steep learning curve where the next step is to install CF on an unmanned SNS platform. After 4 years of gas production with CF a lot has been learned about designing, installing and operating capillary string CF installations.

This paper demonstrates the success of continuous foamer injection by showing increased production and recovery due to foamer but also presents the challenges that were experienced in terms of uptime i.e. poor reliability due to capillary blockages, sand erosion and surface facility upsets etc. The method of tackling these reliability issues to maximize uptime is presented, including an overview of the current and future subsurface and surface hardware components.

*ONEgas is a combined business unit of NAM and Shell UK

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