Envisat ASAR image analyzed by SkyTruth (http://www.skytruth.org) - data courtesy European Space Agency

The Bonga oil field, one of Shell’s largest offshore oil facilities was shut down on Tuesday 20 December after a massive oil spill. The cause? It appears to be a combination of human error and / or equipment failure. What the BBC describes as “leak during a transfer of oil to a tanker” led to a reported 40,000 barrels of crude oil spilling into Nigerian waters.Satellite images show a clearly identifiable slick that measures 356 square miles. Digital scientists Sky Truth have published the shocking images which show an enormous mass of crude oil afloat in the Gulf of Guinea. [UPDATE 22 Dec: The AP reports that the oil spill is “moving to the coast” where it could impact heavily on local fishing communities.]

Skytruth also provided detailed measurements of the visible oil slick:

it is about 70 km (45 miles) long, 17 km (10 miles) wide at it’s widest, and covers 923 square kilometers (356 square miles) of ocean

This is a major spill, even by Shell Nigeria’s shocking standards. In August 2011, Shell was heavily condemned by the UN for failing to comply with basic industry measures and covering up the extent of the pollution in the Niger Delta. Fifty years of oil pollution could take up to 30 years to clean up, according to UNEP.

This latest spill casts serious doubt over the viability of Shell’s offshore drilling programme. Shell has held up Bonga and other “ultra-deepwater” facilities in Nigeria as being safe and secure operations that use cutting edge, clean technology. That a spill of this magnitude could occur despite the technology deployed shows that Shell’s deepwater drilling poses severe risks to the environment.

Deepwater drillling activity has expanded aggressively across the West African rim and poses substantial threats to the coastal environment. In more remote and inhospitable regions like the Arctic, where Shell and other companies are planning to drill next summer, the consequences of a deepwater spill could be even more catastrophic.

North Sea Troubles:

Earlier in August 2011, Shell was responsible for causing the worst oil spill in the area in the UK North Sea for over a decade. A leak in a pipe between an oil well and the Gannet Alpha offshore platform spilled 1,300 barrels of oil into the sea. Shell has yet to clear the remaining oil trapped inside the 4 kilometre subsea pipeline. The company may face a criminal prosecution following an investigation by the Department for Energy and Climate Change. Gannet Alpha is 113 miles (180km) off Aberdeen.

A damning investigation into rusty, ageing rigs in the North Sea by the Express newspaper revealed an appalling level of risk on board Shell’s oil platforms. Bill Campbell, ex-group auditor for Shell International and safety campaigner said:

data showed there were 85 gas releases and 443 dangerous occurrences last year. “The probability of an undesirable event is extremely high,” he said.