Heerema Marine Contractors' giant semi-submersible crane vessel Sleipnir has broken its recently set heavy lifting record with the removal of Shell's 10100 mT Brent Alpha jacket in the UK North Sea.
"This single jacket lift breaks Sleipnir’s recent record for lifting the 8100 mT Jotun-B jacket," Heerema Marine Contractors said Wednesday.
The removal of Brent Alpha jacket is Sleipnir’s fourth decommissioning job for this summer.
For the Brent Alpha jacket removal, Sleipnir arrived at the Brent Field located 186 km northeast of Scotland’s Shetland Islands on July 23, 2020, and completed the project by offloading the jacket onto the quayside at the AF Miljøbase decommissioning site in Vats, Norway on August 11, 2020. The jacket will end its lifecycle by being over 97% recycled.
"The Brent Alpha jacket removal presented novel challenges for Heerema, resulting in unique solutions. During the project, Heerema cut jacket legs at 7.3m diameter using a 288” Diamond Wire Cutting Tool developed alongside CUT UK, especially for the Brent Alpha removal - the largest leg diameter to have been cut this way," the company said.
Also, during the Brent Alpha Heerema removed and transported the conductors with the jacket, which, Heerema says, is an entirely new way of decommissioning. The conductors were suspended on a Heerema Fabrication Group built Conductor Hang-off Frame made for this project.
The semi-submersible behemoth will continue to be busy in the North Sea before swapping the largest lifts for one of the smallest with the installation of Dana Petroleum’s P11-Unity Platform later this year.
According to Hereema, the Sleipnir, delivered last year, has so far removed and transported more than 43900 mT of decommissioned offshore infrastructure for recycling over this summer campaign.
Heerema’s Decommissioning Director, Jeroen van Oosten noted that ‘there were quite some technical challenges during this record-breaking lift. Such as the cutting of the 3 x 288" legs of the platform. However, due to the excellent preparation and perseverance during execution, we successfully delivered this jacket safely and sustainably to Vats for disposal. An outstanding achievement for all involved.’
Worth noting, Heerema's jack-up removal was preceded by Allseas' removal of the Brent Alpha topside's using the Pioneerin Spirit vessel. More on that here.