Decommissioning problems

Greenpeace and Shell is at it again:

To remove large concrete platforms is not an easy task, but should it be allowed to leave them full of sludge and oil residue?
Even concrete deteriorate over time and will probably disintegrate eventually.

As much as I dislike the action by Shell the temperature ensures that the oil will be in a mastic form which over time is consumed by microbial action.

It is not only oil sludge in the storage cells:

So, can anyone tell me the physical difference between Shell abandoning those waste oil tanks on the bottom of the North Sea and scuttling a ULCC full of waste oil, sludge, and oily water in the same place?

The difference is that the Brent Platforms are not being shuttled and will remain structurally intact.

Three of the Brent platforms are Condeep type made from pre-stressed concrete. Oil (and oily water) are stored in large cells below water.

The topsides will be removed by the Pioneering Spirit, while the concrete foundations, with residual sludge and oil water, will be left in place.
Because the cells are full there will be no pressure difference on the concrete structure of the cells.

Here is the decommissioning plan:

And what exactly is the difference between abandoning those waste oil storage tanks on the bottom of the North Sea and sinking a tanker or tank barge full full of waste oil to the bottom of the North Sea?

Shell collected and stored 11,000 tons of waste oil that they are now choosing to abandon on the seabed. That is just plain wrong, wrong, wrong and it makes a mockery of the incredible lengths anyone has to go through to “reef” a ship that no longer contains an ounce of oil.Shell should be forced to leave those concrete tanks as clean as those on a reefed ship.

Listen to the whining about scuttling the forward section of the Wakashio.

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The Condeep GBS on Brent field FYI:
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There is a 250 page study made in 2017 about the different methods of removal that was considered, including re-floating the GBSs with or without the topsides for cleaning and dismantling inshore. (Not an easy task)

Here is a short description of the Condeep GBS that is/was installed in the North Sea in the 1970s and early 1980s:

PS> The idea of GBS MAY get a new lease of lift in the Offshore Wind Industry.

So what?

It wasn’t an easy task to build it, float it out, or place it. Shell had no problem with those tasks and certainly no problem banking the profits from that enterprise. Shell still owns it and absolutely must be held responsible for removing it and its contents to leave the site as they found it.

Maybe the UK government can negotiate with Shell, remove the platform or forfeit all company assets (real estate, bank accounts, leases, cash, vehicles, office furniture, phones, pens, pencils, computers, the whole lot) located in the UK.

Why should the taxpayer have to pick up the trash or the environment suffer the insults left behind after Shell devours the profits from extraction of a national resource?

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The project of decommissioning and removing the platforms from the Brent Field is a 10-year project that also involve the pipelines and subsea infrastructure:

The Pioneering Spirit has just completed removal of the topsides on the Ninian Northern Field, also in nthe UK sector of the North Sea:
https://www.offshore-mag.com/rigs-vessels/article/14182579/pioneering-spirit-removes-north-sea-ninian-topsides

The steel jacket has been left behind for now. It is scheduled to be removed in 2022. No oil storage involved though.