LEIDEN, the Netherlands – Heerema’s semisubmersible crane vessel Sleipnir has set a record for the largest single lift jacket removal.
The Sleipnir removed the 8,100-metric ton (8,929-ton) Jotun-B platform jacket in the Norwegian North Sea for Vår Energi. The platform was installed in 1998 by Heerema’s Thialf, who returned to the Jotun field last year to remove the topsides and conductors.
For the jacket removal, the Sleipnir arrived at the Jotun field 200 km (124 mi) west of Stavanger on Friday, July 11, and completed the project by offloading the jacket onto the quayside at the AF Miljøbase decommissioning site in Vats, Norway, on Thursday, July 16.
According to Heerema, the decommissioning work was completed one day ahead of schedule; and the entire removal scope in the Jotun field was completed in four days.
During this project, skirt piles with diameters 2.7 m (8.9 ft) and 80 mm (3.5-in.) wall thickness were cut subsea, the largest ever done in this way, the company said. Additionally, Heerema fabricated a 40-m (131-ft) long spreaderbar within 2 mm tolerance for a tight, but perfect fit.
In addition, the vessel performed the full removal operations while running on LNG fuel. By using LNG, the Sleipnir reduces CO2 emissions by 25%, NOx emissions by 92%, SOx emissions by 99%, and particulate materials by <99% compared to traditional marine gas oil crane vessels, the company said.
The Jotun-B jacket will end its lifecycle by being recycled up to 99%.