Mammoet completes Munin topside moves ahead of North Sea sailaway

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Mammoet has completed a series of heavy transport and marine operations for the Munin topside, preparing the offshore structure for sailaway from Haugesund, Norway, to the Yggdrasil development in the North Sea.

The work included moving a utility module from a fabrication facility in Thailand, loading it onto a marine transport vessel and transferring it to Aibel’s yard in Haugesund. Mammoet also handled the final site move and load out of the assembled topside onto its transportation barge.

Aibel is responsible for the engineering, procurement and construction delivery of the Munin topside for Aker BP’s Yggdrasil development. Construction was divided between Aibel’s facilities in Thailand and Norway, creating a transport chain that required coordinated heavy cargo operations across two locations.

Mammoet was contracted in late 2023 to support the project’s critical heavy transport and marine activities.

Its first major task involved moving the utility module from Aibel’s fabrication site in Thailand to a nearby quay. The module was then loaded onto a marine transport vessel for shipment to Haugesund.

Following its arrival in Norway, the module and other sections had to be discharged and moved into Aibel’s assembly facilities. The operation was complicated by shallow water at the Haugesund quayside, which prevented the transport vessel from completing a direct load in.

Mammoet addressed the restriction through a transshipment operation. The cargo was transferred from the marine transport vessel to a smaller barge that could approach the quay within the available water depth.

The module was subsequently loaded onto land and moved into Aibel’s assembly hall. This sequence added another interface to an operation that already depended on vessel positioning, tidal conditions and the controlled movement of large offshore components.

The utility module was positioned for mating with the Munin process module inside the assembly hall. Final installation required the module to be placed within demanding tolerances.

Winter weather in Haugesund created further operational constraints during the transport and positioning programme. Mammoet and Aibel coordinated the work around the conditions while maintaining the alignment requirements needed for the mating operation.

For project cargo teams, moving a large module into a covered assembly area can be compared with fitting a building sized component into a fixed frame. Available space is limited, while each movement affects the final position of the structure.

Specialized transport equipment and experienced personnel were mobilized in both Thailand and Norway. Parallel planning across the two sites allowed module fabrication, marine transport preparations and topside assembly activities to progress within the wider construction schedule.

The completed Munin topside was weighed in July to establish its final weight and centre of gravity. These measurements were required before the load out engineering and barge configuration could be confirmed.

After the results were verified, Mammoet moved the assembled topside from the Haugesund quayside and loaded it onto the transportation barge.

The load out was classified as a Class 1 operation and had to be completed within a narrow tidal window. Changes in water level can affect the relative height and stability of the barge during the transfer, making ballast control, timing and coordination central to the operation.

The topside crossed onto the barge after the transport and marine teams confirmed the required conditions. The transfer completed the main scope awarded to Mammoet under the Munin construction programme.

Aibel and Mammoet worked jointly on the planning and execution of the Thailand site move, the Haugesund transshipment, the utility module mating and the final topside load out.

The Munin topside is now positioned on its transportation barge and ready for offshore sailaway from Haugesund to the Yggdrasil development.