Enabling riser pull-in on the Dunlin Alpha platform

Scope of works:

Operation of the Dunlin platform was dependent on electrical power supply from Shell’s Brent Charlie platform. To enable operation beyond 2012 and to cater for a planned increase in production on the Dunlin platform, there was a requirement to boost the platform's own capacity for generating electrical power.

A supply of fuel gas was identified; to access this supply a subsea tie-in was required.

The Dunlin gas export/import development comprised of the following:

• 4” rigid pipeline between the Dunlin SSIV and the Thistle tie-in structure
• 4” flexible or rigid riser from the Dunlin SSIV to the Dunlin platform topsides
• A new Thistle tie-in structure containing diver/ROV operated valves

Scope of supply:

Fisher Offshore were contracted by Technip to supply a 70Te hydraulic winch package for the riser pull-in scope on the Dunlin platform.

Our team was involved from the early stages of the project. We supplied a line monitoring system with data logging for a SIT in Aberdeenshire to assist the engineering of the scope at design stage.

Due to lifting constraints of the platform crane, the hydraulic winch and associated spooling gear (level wind) had to be broken down and supplied in parts, re-assembled and load tested on the platform in the lead up to the pulling scope. The winch wire rope was supplied by James Fisher Offshore (JFO) on a suitable storage drum along with a hydraulic spooler. Our personnel spooled the wire rope on the winch, on the Dunlin platform.

Our personnel operated the winch package throughout the pulling operations. After successful completion of the pull-in scope JFO personnel then spooled off the winch wire and broke down the winch ready for demobilisation back to Aberdeen.

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