The Causeway and Fionn field has been developed as a tie-back to TAQA’s North Cormorant (NC) platform comprising two ESP driven production wells (Causeway & Fionn) and a single water injection (WI) well.
During the initial installation campaign, the two production wells were tied-in to the NC platform via rigid pipelines and a flexible riser and EHC umbilicals were installed and commissioned for each well. The WI well was tied-in to a rigid subsea WI pipeline but could not initially be tied-in to NC. Attempts during previous campaigns at installing the WI flexible riser had been unsuccessful. Upon taking over ownership of the asset as part of the Valiant Petroleum plc acquisition, Ithaca Energy engaged Petrex to manage completion of the WI works on its behalf.
The project objective was to successfully install the 6” WI flexible riser into the J-tube on NC, tie-in the 8” WI pipeline to the riser and commission the WI control system.
Initial investigative surveys identified the cleanliness of the J-tube as the primary reason for previous failures to pull-in the 6” WI riser. Petrex under took a series of workshops with TAQA, Ithaca and various suppliers to ensure engagement from all stakeholders. In order to achieve the desired cleanliness a specially selected jetting system and a series of specifically designed progressive cleaning pigs were procured and deployed using platform services and a subsea winch. Following J-tube cleaning operations the flexible riser was successfully pulled-in by the DSV and NC. The flexible was then successfully tied into the subsea 8” WI pipeline and leak tested prior to completing the subsea control system tie-ins and commissioning the entire subsea WI control system.
James Lund Production Manager for Ithaca Energy commented saying “Operating in the Northern North Sea presents quite unique challenges particularly around weather and sea conditions. With careful planning for these conditions it has been possible to complete this phase of the project safely and efficiently. Petrex have delivered: their care and knowledge on this project has been exceptional. We have further engaged Petrex on our behalf in several more of our Subsea North Sea projects due to their exceptional success rate.”
Petrex, established in 2008 is a leading, trusted and independent Subsea Engineering Consultancy based in Aberdeen.