May Date for Brent Delta's Big Lift
Friday 14 April 2017
Officials at Anglo-Dutch supermajor Shell and offshore contractor Allseas have confirmed that the removal of the Brent Delta platform topsides in the UK sector of the North Sea will likely take place during the first week of May, weather permitting.
Brent Delta is the first of four platforms to be decommissioned at the 40-year-old, Shell-operated field.
The 24,500-tonne topsides will be removed in a single lift by Allseas’ massive twin-hulled Pioneering Spirit vessel, which is undergoing final preparations in Rotterdam.
“We expect to do this in the beginning of May. It’s only weeks away,” Allseas president Edward Heerema told a gathering aboard the vessel on Tuesday.
The vessel will leave The Netherlands around 25 April with a test platform on board, stopping en route to install that unit in the Dutch sector K 17 area before continuing the day-and-a-half-long journey to the Brent field, said Alistair Hope, Brent decommissioning project director at Shell.
“The plan will be to leave Rotterdam, then they’ll go and drop off the test platform back onto its jacket,” Hope stated.
“That’s not really part of our project, but it’s a useful exercise for the crew.”
Pioneering Spirit’s twin bows are divided by a 59-metre wide gap equipped with 16 lift beams. Once on site, the vessel will surround the Brent Delta platform and hoist the platform, which has been reinforced with 300 tonnes of steel to prepare for the job.
The vessel will carry the topsides to the mouth of the River Tees in northern England, where it will be transferred to a custom-built Allseas barge.
The barge will then be towed to Able UK’s Seaton yard near Teesside.
The entire operation could be completed in a week, Hope said.
Able Group business development director Neil Etherington said the company has invested £28 million to prepare the quayside yard for the Brent Delta project, which is expected to last 12 months. “Over the whole project, we could be recycling as much as 100,000 tonnes of steel,” Etherington said.
The platform lift and transfer schedule could be prolonged by adverse weather conditions, Heerema noted.
Although the Pioneering Spirit’s motion compensation systems allow operation in wave heights of 2.5 to 3.5 metres, lowering the topsides onto the barge requires relatively calm seas, he said.
In addition to practice lifts using the test platform, Pioneering Spirit performed its first commercial lift — and set a single-lift record — last year with the removal of Repsol’s 13,500-tonne Yme platform offshore Norway.
“Yme was a relatively large project,” Heerema said. “It was a record lift. But the Brent Delta project is a much heavier and a much bigger platform. It is much more of a test.
“This is the kind of work we had in mind when we built the vessel, and this is one of the key projects that we designed for.”
Bringing the topsides ashore in one piece reduces offshore safety risks and allows the platform to be dismantled “in a very controlled way”, Hope said.
Shell operates Brent with a 50% interest in partnership with US supermajor ExxonMobil.
The field is located 186 kilometres east of the Shetlands in the northern North Sea.