Heerema’s semisubmersible crane vessel Sleipnir has taken aboard the 600-metric ton (661-ton) riser hang off module for Equinor’s Snorre Expansion project from the quayside at Aibel’s yard in Haugesund, Norway.
The Sleipnir entered the Karmsund Strait en route to Haugesund, Norway. In the Karmsund Strait, the narrowest point was 134 m (440 ft), leaving the vessel 15 m (49 ft) of clearance on each side. According to Heerema, this feat that was possible due to a multi-party collaboration with the Norwegian Hydrographic Services working on the S102 project and Kongsberg.
The S102 project is working to enhance safety at sea by making maritime geographical information available to all users of Norway’s coastal and marine areas with the technical support of Kongsberg.
The information shared between these parties enabled Heerema’s simulation center to demonstrate that this project was possible. The company said it enacted three simulations from its simulation center in Leiden to confirm that this project could go ahead. The simulation team considered factors such as currents, tidal shifts, and wind.
By picking up the module from the quayside, there was no requirement for a cargo barge, eliminating the need for loading the module out onto a barge or for barge grillage.
Heerema said this operation was particularly special due to the clearances of the Sleipnir with the seabed, which at times were down to 6 m (20 ft). The company used the S102 team’s demonstrator to see the clearances in real time.
According to Aibel, prefabrication of the riser hang off module began in January 2019 and assembly of the sections started in mid-July. During the following six months, the company assembled, equipped, and completed the module until mechanical completion Feb. 1, 2020. In early March, it was loaded out of the North Sea Hall and prepared for pick-up.
The module is now awaiting an optimal weather window for transport and installation on the Snorre A platform in the North Sea. It will connect the risers that will receive oil from the new wells on the Snorre field up to the platform. Production is expected to start at Snorre A in 1Q 2021.