SOURCE: Yale E360

DATE: June 26, 2018

SNIP: Two decades ago, the North Sea was one of the world’s largest sources of oil, pumping up 6 million barrels a day. That figure is now down to 1.5 million barrels, and the industry is turning to the task of decommissioning the estimated 600 production platforms in the North Sea. The British sector alone contains 470 of them, along with roughly as many other offshore installations, plus 10,000 kilometers of pipelines and 5,000 wells. The British industry expects to carry out more than 200 decommissions between now and 2025.

Many steel rigs will be cut off just below the seabed, and either dragged ashore in one piece or dismantled offshore. A handful of early giant concrete structures, which can weigh as much as 400,000 tons, may have to stay put because there is no way of moving them.

The British industry estimates the final bill at $51 billion, though some analysts say it will be double that. Whatever the price, since decommissioning is tax deductible, the cost will be largely born by taxpayers. Are they getting value for their cleanup cash? Will the expenditure even be good for the environment? Some ecologists say no on both counts.

[T]here has been a growing debate among marine scientists about whether the cleanup may sometimes do more harm than good. For during their lives of 30-40 years, many of the rigs have turned into valuable marine habitats, providing rare hard structures in a sea whose bed is mostly soft sand and mud. They are surrogate reefs, often occupied by rare species.

Linked by ocean currents and pipelines, they form a network of “stepping stones” between natural reefs for species such as cold-water corals made rare in the Atlantic by destructive trawling.

Oil platforms routinely use fluids to lubricate their drills. These fluids are either oil- or water-based and contain metal additives, such as barium sulphate, that increase the density of the fluid and so help prevent well blowouts. After use, the fluids are brought back to the surface, mixed with fragments of rocks from beneath the seabed. Platform operators today attempt to extract and reuse the fluid. But until 2001, much of the remainder was simply poured onto the seabed.

Independent assessments of their ecological impact are rare. A 1995 study by John Gray of the University of Oslo found that they were killing organisms over areas up to 100 square kilometers around platforms. He reported “severe reductions in organisms that are key components of the benthic communities” and that “could potentially have negative effects on fish.”

Some groups take the approach that big oil has a responsibility to leave behind habitat that is as near to pristine as possible. Lyndsey Dodds of WWF UK says: “Having made hundreds of millions of pounds in profits over the past few decades, oil and gas companies operating in the North Sea have a legal, as well as a moral, obligation to clean up their mess.”

But others concede that things are not so simple. “By removing rigs, we risk losing rich biodiversity hotspots that have come to form an integral part of the wider ecosystem.”

“Fishing is restricted up to 500 meters from oil platforms. These restricted zones make up approximately 1 percent of the North Sea area and could provide important refuges for fish,” says Collin. “Once the rig is removed, these marine communities disappear and fishing returns to the area.” For such reasons, a trust policy adopted in 2013 says that “the current presumption of complete removal of offshore infrastructure should be reconsidered.”