Heerema Marine Contractors has filed a plan with Canada’s authorities to use its Thialf crane vessel to remove seven platforms at the Sable Offshore Energy Project off Nova Scotia and install new cranes on the Hibernia platform off Newfoundland.

The Dutch contractor has applied to deploy the vessel for about five months between 1 March and 15 October 2020 and hopes to gain clearance from the Canadian Transportation Agency by the start of next month.

At the ExxonMobil-operated Sable complex, Heerema has been charged with the removal and disposal of topsides and jackets that altogether weigh about 48,000 tonnes.

Individual platform weights range from 750 tonnes to more than 7000 tonnes.

The heaviest component is the Alma jacket, which weighs about 4725 tonnes.

The Thialf will remove the topsides and jackets at location and then move to a nearshore location where the structures will be offloaded onto cargo barges and prepared for transport to Able UK’s decommissioning yard in England.

Sable’s facilities comprise four satellite structures tied back to a hub at Thebaud comprising a wellhead platform, compression platform and processing/accommodation platform.

These facilities were installed between 1999 and 2006 and lie in water depths ranging from 22 metres at the Venture field to 75 metres at North Triumph.

Production at Sable was shut down last year.

Thialf’s second job is expected to last about a week and includes delivery and installation of two platform cranes to Hibernia.

The ExxonMobil-led Hibernia Management Development Company awarded Heerema a contract to engineer, prepare and remove Hibernia’s existing pedestal deck cranes as well as engineer, prepare, transport and install a pair of replacement cranes.

Hibernia’s diesel-electric cranes are being replaced by new fully electric cranes built in Germany, which should help extend the life of Hibernia’s production facilities by 20 years.

The existing cranes will be removed in two pieces — boom and slewing column — while the new cranes each weigh about 160 tonnes and will be installed in one piece.

The Hibernia workscope is set to be executed in summer 2020 in the midst of the Sable programme.

The new cranes will be loaded onto the Thialf’s deck at a nearshore location in Nova Scotia and the vessel will then depart for Newfoundland.

On completing the crane work, the Thialf will return to Nova Scotia to complete the Sable work.

Weekly

Heerema puts Thialf on Sable and Hibernia menu