Shell defended its public handling of the UK's worst oil spill in more than a decade Tuesday as the oil major said it is still tackling a second leak site in the damaged flow line beneath its North Sea Gannet Alpha platform.
In an update on its efforts to stem its biggest UK spill, Shell said it believes flow has now slowed to less than 1 b/d but which is coming from a valve adjacent to the original leak which was plugged last week.
Shell said it had informed authorities of the incident immediately after it was spotted August 10 and claimed it has taken longer than expected to pinpoint the second leak site due to its location while "technical challenges" have hampered its closure.
Shell has come under fire from environmental groups for being slow to acknowledge and release details of the major North Sea leak which had caused a slick over 31 km long and 4 km wide last week.
The oil major acknowledged the spill for the first time August 12, two days after the incident, when the company initially sought to play down the spill, telling press it was "under control."
On Monday, five days after the initial leak, Shell admitted that the spill was "significant" and had already spewed some 1,300 barrels of crude into the North Sea.
The Gannet spill is already the biggest in UK waters since a 450 mt leak from Kerr-McGee's decommissioned Hutton oil field in 2000, according to UK government figures.
Gannet's light, low-wax crude will not reach land due to wave and wind action, Shell has said it believes.
Estimating that less than 70 barrels of oil is visible on the sea surface covering a 26 sq km area Tuesday, Shell said it does not expect to use dispersant to break up the sheen.
Some 180 km east of Aberdeen, Shell operates the Gannet field on behalf of itself and ExxonMobil. Gannet Alpha platform was producing some 5,509 b/d of oil and 24,000 Mcf/d of gas in April, UK government figures show.
Shell shut the subsea production well connected to the flowline last week and began depressurizing the line, but the remaining oil in the isolated connector is still leaking into the sea.
"We have been working to find the source of the much smaller flow of hydrocarbons. It had proved difficult to find because we are dealing with a complex subsea infrastructure and the position of the small leak is in an awkward place surrounded by marine growth," Shell's technical director of exploration and production activities in Europe Glen Cayley said in statement.
Expressing "regret" over the spill Monday, Shell said it was taking the incident "very seriously" and had responded promptly to the leak.
The Gannet Alpha platform remains operational and continues to produce oil, Shell said.
Earlier Tuesday, Cayley defended Shell's response to the spill, telling the BBC's Today radio program that Shell had informed the authorities --the Department of Energy and Climate Change, the Health and Safety Executive, the Coastguard and Marine Scotland -- immediately on finding oil in the water last week.
The company had not gone public because "it took really some time to understand what we were dealing with, principally because the leak location is among some very complex sub-sea infrastructure which was covered in grating so we couldn't access the leak point until we had on station one of these remote operated vehicles and the support ship... that controls it to provide access," he said.
"Only when we had confident information, really, did we want to share that," he said.
"Even at its largest extent, no modeling would have suggested it [the spill] got within 60 km of the shoreline," he added.
Shell said it still does not know what caused the spill, adding the incident will be the subject of both an internal and government-led investigation.
