Mammoet was contracted by Damen Shiprepair to assist with a jack-up leg repair for the Noble Regina Allen drill rig.
The project was performed by jacking-up the 22,000-tonne drilling rig, with Mammoet opting for this method instead of the initial plan of using one of its platform twin-ring containerised (PTC) large ring cranes.
Mammoet was invited by Damen Shiprepair to visit Noble’s Houston offices, where it presented three different approaches for the work at hand.
The first option would be to use a Mammoet PTC210 crane, which would be positioned on the quayside and would lift and lower the leg onto the vessel from above. The second would be to bring a small crawler crane onto the vessel’s deck, also carrying out the repair from above. The final approach would be to lift the vessel using the Mega Jack 5200 system and carry out the repair from underneath.
With easy mobilisation and assembly, the Mega Jack 5200 has been used for topside jack-ups of 42,000 tonnes. “We had to act quickly, especially as the drydock was only available for a relatively short period of time. Whereas normally we assemble the Mega Jack system in 15 days, we realised that we would have to do it in seven days,” said Mammoet project manager, René van Lint. “To achieve this, we scaled up and accelerated the schedule. This was possible due to our large fleet of equipment and by having a team of experts working in two shifts,” he added.
Support blocks were installed onto the rig at the drydock before the rig was floated inside. The dock was then drained, and the rig lowered onto the block, before a configuration of six towers of the Mega Jack 5200 – each with a capacity of 5,200 tonnes – were used. Small mobile cranes and forklift trucks were used to assemble the equipment.
Once all the jacks were in place, the rig was lifted to a height of 35 m, with the leg section – measuring 70 m tall – cut into two parts to fit underneath the rig. The sections were moved into position using SPMTs and the first section was driven into position under the rig and then lifted by the rig’s jacking mechanism.
The process was repeated for the second section, which was welded to the first by Damen Shiprepair, forming the complete jacking leg.
