Earlier this month, Heerema Marine Contractors’ giant semi-submersible crane vessel (SSCV) Sleipnir completed its first decommissioning campaign of the season.
It was a unique project, as Heerema’s Champion installed the same modules for ConocoPhillips at the Greater Ekofisk Field in the 1970s, Heerema said in a statement on Tuesday.
Now, almost fifty years later, Sleipnir has returned to complete the journey.
The decommissioning of the Ekofisk 2/4A platform is the final stage of an important story in Norway’s energy history. The permanent production platform was the oldest on the Norwegian shelf when oil production ended in September 2013.
Now, the Ekofisk 2/4A platform will be recycled up to 99% at the AFEBV decommissioning site in Vats, Norway.
This topsides campaign entailed Engineering, Preparation, Removal, and Disposal/Recycling of five modules, a crane boom, and a burner boom within the Greater Ekofisk Field.
Heerema also developed a dedicated subsea excavator to prepare the jacket for removal later this season by Sleipnir.
According to Heerema, it was particularly appropriate that Sleipnir would perform the decommissioning work as it is the world’s most sustainable SSCV.
Using Sleipnir made an already environmentally friendly process of removing retired platforms from our seas as sustainable as possible, the company explained.
During the project, Sleipnir ran on LNG when next to the platform.
Heerema will also be working on the removal of the platform’s jackets later this year.
Nova module installation
Earlier this month Sleipnir transported and installed the Nova topside module on the Gjøa platform in the North Sea.
The giant vessel picked up the 740mT module from a barge outside Stavanger, Norway, and transported it to Neptune Energy’s operated Gjøa platform. Installation was completed within three hours.
The Nova module will be used for the tie-back of the Wintershall Dea operated Nova field, located about 120 kilometres northwest of Bergen, with a water depth of 370 meters.
As was the case with the ConocoPhillips decom project, Sleipnir ran on LNG during Nova module installation to reduce carbon emissions.