Heerema Marine Contractors’ offshore semi-submersible crane vessel Sleipnir keeps piling up records, the latest being the lift of Shell’s 10,100-tonne Brent Alpha jacket, according to the company
Netherlands-based Heerema Marine Contractors (HMC) reported Sleipnir’s previous record for lifting a single jacket was the 8,100-tonne Jotun-B jacket. Sleipnir has been a workhorse in the decommissioning market, removing and transporting 43,900 tonnes of offshore infrastructure to be recycled for four projects this summer. HMC said the LNG-powered semi-submersible crane vessel will continue to be busy in the North Sea with the installation of Dana Petroleum’s P11-Unity Platform.
For the Brent Alpha jacket removal, 220-m Sleipnir arrived at the Brent Field located 186 km northeast of Scotland’s Shetland Islands and completed the project by offloading the jacket onto the quayside at the AF Miljøbase decommissioning site in Vats, Norway.
HMC reported that the Brent Alpha jacket removal presented novel challenges, resulting in unique solutions. Heerema decommissioning director Jeroen van Oosten noted “There were technical challenges during this record-breaking lift, such as cutting off the three 7.3-m legs of the platform.”
Heerema cut the 7.3-m diameter jacket legs using a diamond wire cutting tool developed alongside CUT UK, especially for the Brent Alpha removal – reportedly the largest leg diameter to have been cut this way.
Also during this project, Heerema removed and transported the conductors with the jacket, an entirely new way of decommissioning. The conductors were suspended on a Heerema Fabrication Group-built conductor hang-off frame made for this project.
Now that the Brent Alpha jacket has been safely and sustainably transported to Vats, it will end its lifecycle by being over 97% recycled.
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