Title: Shell How to Decommission Brent
Duration: 17:58 minutes
Description:
The Brent oil and gas field, operated by Shell, lies off the north-east coast of Scotland, midway between the Shetland Islands and Norway. It is one of the largest fields in the North Sea and is served by four large platforms. It has been a cornerstone of the UK's hugely successful oil and gas industry for 40 years. Now the Brent field is reaching the stage where almost all the available reserves of oil and gas have been retrieved. The next step in the lifecycle is to decommission Brent’s four platforms and their related infrastructure.
As the operator, Shell is required to submit a decommissioning programme to the Department for Business, Energy and Industrial Strategy with detailed recommendations for closing down and making safe the four platforms and subsea infrastructure of the Brent field. Ten years of research, engineering studies, expert input, consultations and scientific assessments have gone into this process.
Shell How To Decomission Brent Transcript
[Background music plays]
Bright, uplifting music
[Video footage]
A Shell employee overlooking the Brent field. Various shots of Shell employees at work.
[Voiceover]
The Brent oil and gas field has provided energy for the UK for 40 years. A joint venture between Shell and Exxon Mobil, it has created and sustained tens of thousands of jobs and delivered a number of technology firsts. At its peak, it produced enough energy to power half the UK’s homes. But with reserves now depleted, Brent will follow in the footsteps of dozens of other North Sea platforms and be decommissioned. As the operator, Shell has to recommend the best methods of doing that.
[Text displays]
How To Decommission Brent
[Animated sequence]
Zoom through clouds to an aerial view of the North Sea. A map shows the location of the Brent oil field and the four platforms; Delta, Charlie, Bravo and Alpha. Yellow dots denote the location of the 154 wells. The 103 kilometres of pipeline spanning from each platform are illustrated by red lines.
[Voiceover]
The Brent Field is made up of 4 platforms, 154 wells and 103 kilometres of pipeline.
Interview with Alistair Hope
[Text displays]
Alistair Hope
Brent Decommissioning Project Director
[Title]
Brent Decommissioning Project Director
[Alistair Hope]
It’s an enormous task. The platforms are interconnected and interdependent so that adds to the complexity.
[Video footage]
Shot of a vessel at sea towing one of the platforms behind it. Shot of the vessel being battered by high waves.
[Voiceover]
These megastructures were built to withstand 200 mile per hour winds and waves 25 metres high. Their robust design raises challenges for today’s engineers.
[Video footage]
Shot of several engineers at work in a meeting room. One engineer is pointing something out on a diagram.
[Voiceover]
This will be Shell’s biggest decommissioning project, and one of the largest undertaken in the North Sea.
Interview with Duncan Manning
[Text displays]
Duncan Manning
Brent Decommissioning Asset Manager
[Title]
Brent Decommissioning Asset Manager
[Duncan Manning]
What often surprises people is that these platforms weren't designed with decommissioning in mind. They were designed at the height of an energy crisis to extract the oil and gas from the reservoir.
[Animated sequence]
View of the four Brent platforms in the ocean. View of the base structures on the sea bed. Illustrated in yellow is debris.
[Voiceover]
Shell has collaborated in the development of a bespoke solution to remove oil trapped in sub-sea storage cells. It is also collecting debris that has been washed off platforms during storms.
Interview with Alistair Hope
[Alistair Hope]
We have 154 wells, and that is actually where a lot of the effort in decommissioning goes into plugging and making safe those wells so that the reservoir doesn’t leak in the future.
[Video footage]
Close-up shot of machinery and an engineer peering into the sea, watching the machinery lower a long pipe into it.
[Voiceover]
Over 1.7 million litres of concrete has been used so far to permanently seal wells. Plans are also in place to remove the four topsides.
[Video footage]
Close-up shot of one of the platform topsides with the other platforms visible in the distance.
[Voiceover]
Together the topsides weigh a colossal 93,000 tonnes. They will be cut from their legs, and in the world’s largest ever off-shore lift, they will be transferred onto a barge and sailed to shore.
[Animated sequence]
View of one of the platforms. CGI animation of a heavy lift vessel removing one of the topsides and sailing away. Three of the heavy legs can be seen left standing in the ocean.
[Video footage]
Aerial view time-lapse footage of a platform being deconstructed.
[Animated sequence]
Underwater animation showing light shining down into the water to the seabed followed by the below mentioned titles.
[Text displays]
Gravity Base Structures
Cell Contents
Drill Cuttings
Alpha Jacket Footings
Pipelines
[Voiceover]
For the other parts of the field Shell has completed a “comparative assessment”.
[Video footage]
Aerial views of a platform with cranes on.
[Voiceover]
This weighs up the pros and cons of each decommissioning option under five main criteria. Safety, environmental, societal, economic, and technical.
[Animated sequence]
Shot of five cylindrical tanks displaying the below mentioned titles on each one.
[Text displays]
Safety
Environmental
Societal
Economic
Technical
[Video footage]
Shot of a man at work in a lab with many pipes and gages. He is running several tests.
[Voiceover]
Hundreds of expert studies have been commissioned and the results analysed and verified by a group of independent scientists.
[Video footage]
Shot of several scientists in a meeting room, discussing and watching a presentation.
Interview with Professor John Shepherd FRS
[Text displays]
Professor John Shepherd FRS
Ocean and Earth Sciences, University of Southampton
[Title]
Ocean and Earth Sciences, University of Southampton
[Professor John Shepherd FRS]
I really feel very strongly indeed that having truly independent review is a vital part of this process.
[Voiceover]
Shell has shared its findings widely with interested parties. Their feedback, the results of the comparative assessment, and the independently verified research has informed Shell’s recommendations for decommissioning the Brent field.
[Video footage]
Outside shot of a building with three flag posts. One is a flag with the Shell logo, another the Union Jack. Shot of one of the topsides with another in the distance.
[Animated sequence]
Underwater animation showing light shining down into the water to the seabed. Gravity Base Structures is written in white caps.
[Text displays]
Gravity Base Structures
Interview with Katy Lin
[Text displays]
Katy Lin
Decommissioning Project Engineer
[Title]
Decommissioning Project Engineer
[Katy Lin]
Gravity base structure, or GBS as we call it, is made up of a steel skirt which anchors the structure to the bottom of the seabed. It’s made up of some cells for storage and legs.
[Animated sequence]
View of one of the platforms in the ocean. Underwater footage of steel skirt. The cells are highlighted in orange and the legs in yellow.
Interview with Alistair Hope
[Text displays]
Alistair Hope
Brent Decommissioning Project Director
[Title]
Brent Decommissioning Project Director
[Alistair Hope]
These gravity base structures are made of heavily reinforced concrete. Each GBS weighs around 300,000 tons.
[Voiceover]
Shell has investigated completely removing the structures from the sea.
[Animated sequence]
Underwater footage of a GBS right down to the seabed.
Interview with Katy Lin
[Title]
Decommissioning Project Engineer
[Katy Lin]
When these GBSs were positioned out offshore in the 1970s, they would’ve been towed out, filled with ballast to ensure that they were grounded on the seabed.
[Video footage]
Archival footage of a GBS.
[Voiceover]
To refloat the gravity base structures, this installation would need to be reversed.
[Animated sequence]
Aerial view of a GBS. Underwater view of one of the legs highlighting the cells. The emptying, sealing and filling process is illustrated. Finally, the whole structure is lifted up off the sea bed.
[Voiceover]
Cells would need to be emptied, sealed and filled with air to induce buoyancy. The base would need to be excavated and hydraulics used to prise it from the sea-floor, and a method of altering the buoyancy would need to be found for its journey to the surface.
Independent studies suggest that successfully refloating the GBS could prove extremely difficult.
[Video footage]
Katy and James discussing at a table filled with papers and a laptop.
[Katy Lin]
Nobody’s ever done this before. You can have a scenario called pop-up where you would lose control of the GBS structure.
[Voiceover]
Attempting to lift the structures from the seabed could also collapse them.
Interview with Alistair Hope
[Alistair Hope]
There is technically an extremely high risk of failure and also a very high safety risk, far higher than we would accept in any other part of our operations.
[Video footage]
Shot from a helmet-cam from a Shell employee inside one of the structures. Another Shell worker can be seen holding a very large chain. The employees are lowering themselves with the use of ropes from a GBS towards the sea surface.
Interview with Duncan Manning
[Text displays]
Duncan Manning
Brent Decommissioning Asset Manager
[Title]
Brent Decommissioning Asset Manager
Duncan Manning
Based on 30 years of data gathered on North Sea operations, that would indicate that we’d have at least one fatality per gravity base structure being refloated, and that is a risk which I am not prepared to entertain.
[Video footage]
Shot of several people at a board table with laptops looking up at a screen.
Interview with James Blackburn
[Title]
Brent Decommissioning HSE Manager
[James Blackburn]
So having done some deep technical studies and also dialogue with our independent review group, we’ve come to the conclusion that we won’t carry that option forward.
[Animated sequence]
CGI animation of three concrete legs sticking out above the sea surface. A red flashing beacon can be seen atop one of the legs. Underwater shot of the GBS illustrating the legs being cut down below sea level.
[Voiceover]
Shell has also considered leaving the GBS in place and adding navigation aids, or cutting the legs 55 metres below sea level in line with international maritime organisation guidelines.
Interview with James Blackburn
[Title]
Brent Decommissioning HSE Manager
[James Blackburn]
To better understand the complexity around cutting concrete, we have actually done some trials on shore where we’ve formed reinforced concrete, and we’ve also compressed it to try and replicate the conditions that are out there actually on the GBSs.
[Video footage]
Shot of an employee drilling into concrete. Shot of John Gillies and another man discussing and looking at a diagram on a screen.
[Voiceover]
While they’ve achieved the cut in a test on land, there’s concern it may not work in practice.
Interview with John Gillies
[Text displays]
John Gillies
Brent Decommissioning Execution Manager
[Title]
Brent Decommissioning Execution Manager
[John Gillies]
As you may appreciate, making a cut without trapping that wire with 6,000 tons of dead weight bearing down on that cut surface in a marine environment where you're dealing with the effects of waves, wind, a dynamic situation, is certainly extremely challenging.
[Video footage]
Footage of a vessel rising and dipping in rough seas.
[Voiceover]
The cost of this partial removal would be very high, which is something Shell is required to consider.
Interview with Roger Esson
[Text displays]
Roger Esson
Chief Executive, Decom North Sea
[Title]
Chief Executive, Decom North Sea
[Roger Esson]
The UK tax payer will be funding part of the cost of decommissioning, so it’s really important that the operators are looking to carry out the work in the most cost-effective manner.
[Video footage]
Shell employees at work. A helicopter can be seen in the distance. Shot of the helicopter landing. Aerial shot of one of the platforms. Shell employees examining equipment and moving a shipping container.
[Voiceover]
Brent’s profits were taxed in excess of 70%. It paid £20 billion in today’s money in taxes. Shell can now claim a 70% reimbursement on the cost of decommissioning from the taxes it previously paid. And while the final costs of decommissioning are not yet known, Brent will remain an overwhelmingly positive contributor to the UK Treasury.
[Video footage]
Shot of men at a table with various laptops showing pie charts. Shot of Alistair pointing to an image of a cross-section of one of the platforms whilst explaining to the man beside him.
[Voiceover]
Having weighed up all the options, Shell is not recommending the partial removal of the legs.
Interview with Alistair Hope
[Title]
Brent Decommissioning Project Director
[Alistair Hope]
Our recommendation based on 10 years of study and independent review and analysis by our independent review group is to leave the concrete gravity base structures with the legs up in place.
[Animated sequence]
360° animation of three concrete legs sticking out above the sea surface. One of the legs has a flashing beacon atop it.
[Voiceover]
This would involve capping the legs with concrete and installing navigation aids. The structures would be marked on maritime charts, and in FishSafe, the fishermen’s GPS warning system.
[Animated sequence]
Animation showing the three concrete legs being capped with concrete. Animation of a maritime chart denoting the location of the structures.
Interview with Duncan Manning
[Title]
Brent Decommissioning Asset Manager
[Duncan Manning]
One of our key contractors came to the conclusion that actually the collision hazard was about one in every 10,000 years, so well under any accepted standard.
[Video footage]
View of a harbour with several vessels. Close-up of a computer screen.
[Voiceover]
Experts estimate that the GBS legs will degrade to below sea level in around 250 years. Then their position would be marked with buoys.
[Animated sequence]
Underwater view of the GBS legs.
[Video footage]
Aerial view of one of the platforms.
Interview with Roger Esson
[Title]
Chief Executive, Decom North Sea
[Roger Esson]
The option to leave the gravity base structure in place really mirrors what’s already happened in the Norwegian sector where the structures have been left in place with navigation aids on there to aid shipping and fishing.