Capping a busy year in decommissioning, Heerema Marine Contractors (HMC) reported in December its deepwater construction vessel Thialf completed an eight-month campaign supporting the removal of the Sable Project’s offshore facilities in eastern Canada
The decommissioning work, undertaken on behalf of ExxonMobil Canada, entailed the engineering, preparation, removal and disposal of seven platform topsides, seven jackets and 22 conductors off the coast of Nova Scotia. Five barge loads carrying Sable platform components, weighing approximately 48,000 tonnes, were towed across the Atlantic by the Heerema tugs Kolga and Bylgia, each of which has a bollard pull of about 200 tonnes.
HMC reported an onboard crew of approximately 300 international and domestic workers, aided by support vessels and helicopters, completed the work. While it faced challenges due to the global pandemic, HMC said the removals campaign involved multiple crew changes and was completed safely without a single case of Covid-19.
Components from the project were typically transported from the Sable Field to Chedabucto Bay to be sea-fastened before their transatlantic voyage to the decommissioning yard. After dismantling at the Able UK decommissioning yard in Hartlepool, England, 99% of the material will be recycled primarily into steel.
The Sable Project was one of six decommissioning and removal projects supported by HMC in Canada and the North Sea using its highly capable offshore heavy-lift and construction vessel fleet. In the North Sea, the world’s largest semi-submersible crane vessel Sleipnir was deployed for five projects: the Cat3 Ekofisk Ekoa topsides and jacket removals and Jotun-B jacket removal in the Norwegian sector, the Shell Brent Alpha jacket removal in the Scottish sector and Total Tyra Removal phase in the Danish sector. HMC reported the six projects resulted in about 90,000 tonnes of offshore facilities being removed.
While not as large as Sleipnir, the dynamic positioning class 3-capable Thialf can perform tandem lifts of 14,200 tonnes.
Developed in the late 1990s, the Sable Offshore Energy Project produced more than 2Tn ft3 of natural gas and liquids until it ceased operations on 31 December 2018.
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