Offshore installation and decommissioning contractor Allseas has shared a video of its removal of Repsol Norge's 30,000 tonne Gyda platform.
The video, featuring its Pioneering Spirit heavy lift vessel follows the removal and delivery of the platform's 11,000 tonne jacket to Aker Solutions’ disposal yard in Stord, Norway, less than 48 hours after removing it from the southern Norwegian Sea.
The latest job for the vessel’s new jacket lift technology was one of the heaviest, but well within the system’s 20,000-tonne lift capacity. The decommissioned drilling and production topsides were delivered to the yard at Stord by Pioneering Spirit in May this year. Aker Solutions expects to recycle around 98% of the facilities.
Split across two campaigns to allow for the vessel’s busy schedule, Pioneering Spirit completed the removal, transport and load-in to the disposal yard of the entire Gyda platform, its 32 conductors and template in 12 days.
Allseas says the jacket was vertically fabricated and installed back in the early nineties, which meant that the structure could not sustain loading in the horizontal position during transport. It said its jacket lift system offered a solution: transporting the jacket in a near-vertical position (60 degrees) and direct load-in to the quayside.
To facilitate removal of the jacket, the structure’s 24 foundation piles were cut below seabed level. Main hoist blocks suspended from the Jacket lift system (JLS) beams were connected to pre-installed rigging and the entire structure lifted and aligned with the lifting beams. As the jacket was vertically fabricated and installed, the structure could not sustain loading in the horizontal position during transport.
The solution of transporting the jacket in a near-vertical (60%) position, with interface supports and grillage made delivery of the complete jacket to the yard possible.
Unlike conventional lift vessels, Pioneering Spirit only requires days in the field to remove entire platforms and subsea facilities, eliminating the need for multiple trips and a support fleet. Saving time and reducing vessel operations to a minimum significantly reduces the vessel’s emissions footprint.
Gyda is a field in the southern part of the Norwegian sector in the North Sea, between the Ula and Ekofisk fields. The field was developed with combined drilling, accommodation, and processing facility supported by a steel jacket standing in 66 m water depth.
The platform started producing in 1990, and a decommissioning plan was submitted in 2016.