Page 15: of Offshore Engineer Magazine (Sep/Oct 2016)

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FIELD OF VIEW

Beginning of the end

Putting the Brent ? eld online in 1976 was a feat.

Decommissioning the ? eld’s four massive platforms is equally challenging. Elaine Maslin sets out Shell’s latest plans and how it came to them. hen Shell’s 24,200-tonne Brent Delta topsides is lifted,

Photo from Shell.

End of an era at Brent.

W now scheduled for 2017, it will be the heaviest lift ever conducted offshore using the world’s largest ve ssel by one of the largest sets of infrastructure in the North Sea. Peak displacement. production from the four Brent platforms, of three different

It will be an immense feat, not unlike the original feat to designs (Bravo and Delta – Condeep, Charlie – Sea Tank, and install the four Brent mega-structures, three of which are Alpha – steel jacket), was 500,000 bbl in 1982. Production at ca.300,000-tonne gravity base structures (GBS), some 186km Brent Delta stopped in 2011, followed by Alpha and Bravo in northeast of Shetland, in the harsh northern North Sea back 2014. Charlie is still producing and will reach its 40th anni- in the 1970s. versary this November, despite the ? eld having initially been

While the record lift will hit the headlines and leave many expected to produce for just 25 years. in awe, there have been a string of other feats on this project,

The Brent decommissioning campaign started in 2006, some including exploration into inner space, with the help of NASA, 10 years ago. A large focus – “the big ticket item” – has been and creating a moon pool on a 40-year-old platform, not to men- on P&A work, with some 154 wells and around 400 wellbores tion the 400+ wellbore plug and abandonment (P&A) campaign. in total to abandon. P&A work on Delta is complete, with work

There has also been intense work to assess how to deal with now focused on down-manning. P&A work is ongoing on Bravo, the three massive GBSs and the 31,500-tonne steel jacket. Shell’s with work on Alpha also ramping up – the Saipem 7000 recent- conclusion is that they would be best left in place, at least in part. ly replaced a crane on Alpha to enable P&A work. Meanwhile, “If you think back to 1971, when the ? eld was discovered, on Charlie, an integrity program is being performed, with the with ? rst oil in 1976, which was really fast, they needed bril- support of Prosafe’s ? otel Regalia, ahead of P&A work there. liant engineering,” says Alistair Hope, Shell project director.

Heavy decisions “These are engineering marvels. Now we have to decommis- sion them, we need that same ingenuity However, what’s remarkable about this project is the immense and great engineers to allow us to do this.” amount of background work involved: some 300 reports have

Business opportunity manager Duncan been produced, all of which have been scrutinized by an inde-

Manning, a former Lieutenant Colonel in pendent review group. the Royal Marines, with three tours in Much of this work has been to inform the decision on how

Afghanistan under his belt, says the Brent to deal with the three GBS foundations, on Charlie, Delta and project is akin to the Olympic Games, on Bravo, and the 31,500-tonne (including marine growth) Alpha which he worked in 2014, in scale, com- steel jacket. This has meant understanding the impact on the

Duncan Manning plexity, dif? cult environment and the need environment and other users of the sea, the impact onshore, to work closely with a large number of stakeholders. technical feasibility, and cost, of all the various options,

Manning says. Alternative uses, from offshore wind to carbon

Discovery to COP capture and storage, have also been assessed – in detail.

Brent was discovered in 1971, in 140m cold rough water To remove the footings of the steel jacket would mean either depth. First production was achieved just ? ve years later, with boring down through the tops of the footings or excavating oedigital.com September 2016 | OE 17 017_OE0916_Field of View_jl1.indd 17 8/23/16 6:29 PM