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Quitting the North Sea.

Dozens of North Sea oil and gas facilities will be decommissioned in the coming years. How are operators coping with the scale of the challenge, and what will be left when the platforms are gone?

Crowded around the table, the players loom over the North Sea like gargantuan creatures risen from the deep. Below, the oil and gas platforms dot the map in bright red, braced for the coming storm.

By the end, each of the rigs will be gone, leaving a twisting puff of mud in the rise and fall of the frigid water.

This is the decommissioning game: a monumental challenge in miniature, encouraging the industry delegates at the SPE Offshore Europe (OE17) conference to come together in a spirit of strategic collaboration.

In the next 10 years, over 100 platforms will be completely or partially removed, and more than 1,800 wells plugged and abandoned. The scale of the task is massive. But how are operators approaching the challenge, and what will follow when nothing remains in once-bountiful zones of the cold North Sea?

Boom to bust

In June 2014, a barrel of crude oil could set you back $115 (68 [pounds sterling]). Then, prices plummeted. By the end of the year, you might pay $55 (35 [pounds sterling]); in January 2016, less than $30 (21 [pounds sterling]).

The price collapse, which has since seen only mild recovery to about $50 (37 [pounds sterling]), killed investor confidence. Boom turned to bust and, rather than installing shiny new platforms, oil and gas operators were faced with the prospect of large-scale decommissioning and well abandonment.

Industry body Oil & Gas UK forecasts that 17.6bn [pounds sterling] will be spent on decommissioning on the UK Continental Shelf between 2016 and 2025. Nearly 7,500km of pipeline will stop transporting the fossil fuels that fed massive industrialisation and consumer shifts. "We're not going to run out of wells to abandon in the near future," says Paul Howlett, founder of Sudelac, a supplier creating well abandonment tools.

The feeling at OE17 in early September is of an industry awakening to the task at hand. It is the first iteration of the event since 2015, delegates only now assessing the full impact of the dramatic price drop. Perched on the low, rolling coastline north of Aberdeen city centre, the venue is just over the horizon from rigs condemned by the slump.

There is hardly time to catch breath between the decommissioning talks, workshops and roundtables filling a packed schedule of events dotted around the mammoth Aberdeen Exhibition and Conference Centre. You are sometimes forced to choose between key topics--new technology for abandonment, or the challenges of regulation?

For the first time, there is also a dedicated Decommissioning Zone, where suppliers hawk their latest kit and operators seek solutions to meet their three main goals: efficiency, safety and low costs.

"The industry could once be accused of sleepwalking into decommissioning but I don't think that is the case any more," says Bill Inglis from well-flow management company Expro. "A lot of companies are thinking about it ahead of time."

A holistic view

It is in the Decommissioning Zone that Dorothy Burke's strategic 'board game' plays out. A decommissioning consultant for advisers Xodus Group, Burke created the experience as much more than a temporary exhibit and hopes the format will be adopted by individual operators and groups as they plan their staggered retreats from the North Sea.

At OE17 volunteer players come from across the oil and gas spectrum, each taking an assigned role likely to be outside their day-to-day business, such as regulator, supply-chain representative or other sea users--fishermen and environmental groups.

The delegates are tasked with decommissioning an operator's entire North Sea portfolio within 10 years as strict new regulations roll in like a storm surge. As the demonstration begins, an initial flurry of questions quickly highlights the complex web of considerations required: differences in local regulations, the cost for operators and taxpayers, environmental impact, and the safety of workers feature on a seemingly endless list.

For the costly, complicated and hazardous process to be a success, industry players must take a "holistic view," says Burke.

The game is built to encourage collaboration and open discussion, things often in short supply in a secretive and competitive industry. Decommissioning is " a challenge we all have to face, and there is no real benefit to one of us doing it better than the others. We are all in this together," says Burke, while another exhibitor says it should be viewed as "a non-competitive sport".

Greater collaboration should help operators keep costs down--something of interest not just for the industry, but wider society. Public coffers are expected to cover about half of the 60bn [pounds sterling] likely to be spent on decommissioning.

"We have a shared goal in keeping the costs as low as possible ... with better skills and more innovation and more technological advances," says MP Andrew Jones at OE17's opening plenary session.

Despite a deep gloom around unprofitable spending bubbling just beneath the surface, the exchequer secretary to the Treasury attempts a positive spin on the situation.

With one eye surely on Brexit, he claims there is a "window of opportunity" for the UK to become world leader in decommissioning and refers to Aberdeen's new multi-million pound Decommissioning Solution Centre, set up to mix academic knowledge with industry clout and business efficiency.

Others also talk confidently about the UK leading the way. Testing, inspection and certification company Bureau Veritas (B V) is creating guidelines for the global oil and gas industry based on new UK legislation.

The laws will " set the benchmark for best practice for other regions, so if we can help our clients and the industry understand what's required of them to be compliant with the legislation in the UK, then they can take that to other regions," says BV's Paul Shrieve.

"There may be variations from the theme in different locations but at least if you've got a common structure to start with then you can work from there to have some sort of industry requirement."

That BV's assistance is required highlights another gratuitously complicated aspect of decommissioning--a regulatory landscape as lumpy as the sea floor being plumbed. "Rules and regulations are a shifting landscape," says Inglis.

A frequently mentioned example is the depth of cement plugs needed to seal abandoned wells, ranging from 100m in some areas to just 8m in others. Engineers reportedly bemoan an "unscientific" approach to the variations, although they can be down to environmental differences

Hurdles appear

As with the strategy game players, operators must consider the varying regulations as they begin planning decommissioning projects. The whole process takes about 10 years--of that, planning might last four years.

"You have got to make the right decision up front," says Steve Gilbert from Lloyd's Register.

Hurdles appear immediately. After operators assess their wells and platforms for profitability, they must take stock. Working with rigs built in the 1970s and 1980s, companies are often surprise by what they find.

"Sometimes people don't mow what they have got," says Gilbert. According to anecdotal evidence, one operator found five wells they did not know they owned. Alterations are constantly made, and might not have a solid basis to start with: "A lot of the older records are more aspirational than accurate," he adds.

Not just re-engineering

After that, the real challenge begins." Some things can't be deconstructed the way they were constructed," Gilbert says. "A cup of tea is a good example."

Decommissioning is "not just reengineering," says Shrieve. "People seem to think we just do stuff in reverse, taking the bits off. But it's a bit more sophisticated than that."

Operators are often keen to remove platform sections gradually as oil or gas continues to flow to the surface but, while this allows them to maximise profits, it creates complex and changing safety requirements for the remaining workers.

Floating platforms can be moved practically intact. Crews stop "dynamically positioning" them, allowing tugs to gently drag them away from their long-term homes.

As the sector grows, operators are also introducing more ambitious methods. In April, Allseas set a world record for the heaviest weight lifted in one go as it heaved the 24,000-tonne Shell Brent Delta topside on to the world's biggest construction vessel, the Pioneering Spirit. About 186km off the north-east coast of Shetland, engineers positioned the twin-hulled vessel around the three-legged rig. The supports were cut before the Pioneering Spirit lifted the structure in seconds with eight hydraulic lifting beams.

Journey to the scrapyard

The 382m-long ship then took the topside to a scrapping yard near Hartlepool, although other platforms face much longer voyages, often ending up at yards in Turkey, India or China, where workers risk their lives slicing the out-of-water structures apart with blowtorches.

Apart from elaborate jobs like Allseas' record-breaking lift, decommissioning above-sea structures is often unadventurous as companies strive to minimise costs. Beneath the waves, however, many believe there is more room for innovation.

" If there is one area we need a fresh look with technology, it's well abandonment," says Roger Esson from Decom North Sea, a non-profit-making organisation set up to help share decommissioning knowledge across the industry.

A different estimate is found at every OE17 conference stand, but companies expect to spend between 45% and 60% of their decommissioning budgets on well abandonment. The complex submarine process can vary from well to well, requiring significant planning from operators.

Cement fills of varying lengths are piped in on top of plugs, aiming to stop oil or gas escaping. The plugs are tested to withstand pressures of up to 500psi, and cameras check for bubbles in the cement as hydrocarbons try to force their way out from beneath the rock.

Some companies are experimenting with new technology, including ferromagnetic or electromagnetic cement to enable easy imaging of the plug. Others are exploring radical techniques, such as substances to cause accelerated corrosion of what is left behind, and autonomy and artificial intelligence are likely to play a bigger role in the years to come.

Recycle and reuse

After the wells are plugged and the platforms dragged away, leaving seemingly empty zones of North Sea above cement fissures and pipeline 'trees', do the rigs have any future?

"At the moment the majority is scrap," says Zero Waste Scotland's Scott Bryant. "Some 95% is technically recyclable, but most is cut up in Scotland, the rest of the UK or Norway and then typically sent abroad to be properly scrapped. At the moment it's not technically viable to do in the UK and the steel recycling routes are fairly full."

However, Bryant hopes the story may change in the coming years as decommissioning matures. Steel tubes from platforms are already often recycled into pylons, but Zero Waste Scotland believes the old structures might provide material for new homes and railways.

"When you're up close you really realise how big the structures are and how much opportunity there is," says Bryant. "If there is a will and people sit down and sort it out, there is a way to make it work."

Other options include 'rigs-to-reefs', a process popular in the Gulf of Mexico where old platforms are sunk to create habitats for marine organisms. Fishermen and oil companies often support the idea where possible, although other sea users claim it is little more than ocean dumping and could have a more negative than positive impact on wildlife.

Whatever happens to the North Sea's old platforms, it is vital that operators consider all possible options. With public money and the environment at stake, we are all players in the decommissioning game.

Decommissioning: the facts and figures


Decommissioning accounted for 2% of total industry expenditure in 2010--by 2015, that increased to 5%


More than 100 platforms will be completely or partially removed


end-of-production dates were brought forward in 2016
Norway   33
UK       153


186 projects are forecast for decommissioning within 10 years


Well plugging and abandonment is the largest category of expenditure on the UK and Norwegian Continental Shelves at around 50%


Close to 7,500km of pipelines are lined up for decommissioning

All figures from Oil & Gas UK

Caption: Pioneering Spirit, the largest construction vessel in the world, lifts the Brent Delta topside

Caption: Players start Xodus Group's decommissioning game at SPE Offshore Europe

Caption: The 17,000-tonne Transocean Winner drilling rig ran aground in north-west Scotland in August 2016, after storms
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Title Annotation:OFFSHORE
Author:Flaig, Joseph
Publication:Professional Engineering Magazine
Geographic Code:0NORT
Date:Oct 1, 2017
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