Giant oil firms have spent more than four decades pumping billions of pounds worth of oil from the seabed. But now decommissioned rigs in the North Sea are at the centre of an environmental storm with an oil giant under intense pressure to rethink plans to leave some of the platforms in the sea.
Several hundred oil drilling platforms in the waters off Scotland are due to be decommissioned over the next three decades as they approach the end of their operational lifetime. Due to the cost and difficulty of dismantling the structures – each of which can be as tall as the Eiffel Tower – Shell proposed removing only the topside of its four Brent platforms, leaving the huge concrete legs in place.
That resulted in the controversial suggestion that oil mixed with sediment in 42 out of 64 concrete storage cells – each up to 66 feet in diameter and 200 feet high, around the height of the Scott Monument in Edinburgh – should remain on the seabed. These could remain for up to 500 years after the platforms have been decommissioned.
The plans have raised alarm in some quarters over the impact of leaks from the estimated 11,000 tonnes of raw oil and toxins remaining in the base of the four Brent installations – Alpha, Bravo, Charlie and Delta, all put up in the East Shetland basin in the 1970s. It has emerged that a report of an expert evaluation group commissioned by the Dutch government has provided a critical analysis of the position and recommends a clean-up be carried out as agreed more than 20 years ago in international treaties. See Brent Decommissioning Derogation: An evaluation. The special treaty known as Ospar, which was adopted in 1992, states that rigs, including their contents and pipelines, must be removed from the sea after decommissioning.
The experts said that removing all contaminated materials “presents the most certain solution”. They say staying true to Ospar “not only avoids passing on potential problems to future generations” but also prevents “large amounts of negative public attention as was the case in the decommissioning of Brent Spar in the 1990s”. When Shell proposed sinking the Spar oil storage buoy in 1995, it prompted protests by Greenpeace, petrol boycotts in Germany and a falling share price. The company was eventually forced to back down and find a more environmentally friendly plan.
In October 2019, Greenpeace activists from the Netherlands, Germany and Denmark boarded two oil platforms in Shell’s Brent field in a protest against the plans. They scaled Brent Bravo and hung banners saying “Shell, clean up your mess!” and “Stop Ocean Pollution”.
The 2019 report revealed that an earlier independent review group(that took place in 2017)said that a “leave in place” solution with appropriate navigational markers and safety zones gave “a risk in relation to shipping impact that Shell regarded as acceptable”. The report added: “However, although the estimated probabilities of a collision may be low on a per annum basis, the consequences could be catastrophic and result in major injury and loss of life or serious marine pollution.”
Excerpts from North Sea oil decommissioning: pressure grows on Shell to back down, the Herald, Oct. 20, 2019