--Shell divers close relief valve to stop affected pipe leaking
--Removal of remaining crude in pipeline will "take time"
--"Extensive" monitoring phase to begin
--No impact so far on sea, bird life
LONDON -(Dow Jones)- Royal Dutch Shell PLC (RDSA.LN) has stopped a leak from an underwater pipe at its Gannet Alpha platform that had been spilling crude oil into the North Sea for more than a week, the Anglo-Dutch major said Friday.
"Today, Shell divers closed the relief valve from which oil had been seeping at a rate of less than one barrel a day," said Shell. "Now there will be a phase of monitoring the flowline [the pipe] to check that it remains sealed," it added.
Shell has been battling a leak at the 18-year-old installation since last Wednesday. It estimates some 218 tons of crude oil have already spilled into the sea since then, though this isn't expected to reach land. Shell and U.K. environmental authorities say they expect the oil to be naturally dispersed through wave action.
"It is clearly good news that Shell has managed to close the valves," said Scottish Environment Secretary Richard Lochhead.
Meanwhile, Glen Cayley, technical director of Shell's exploration and production activities in Europe, said: "Closing the valve is a key step. It was a careful and complex operation conducted by skilled divers, with support from our technical teams onshore [but] we will be watching the line closely over the next 24 hours and beyond."
However, some 660 tons of residual oil remain in the depressurized pipe, which has been secured on the seabed with concrete mats. The next phase of the operation will be to remove this remaining oil from the pipe, though Cayley cautioned this will take time.
The U.K. Department of Energy and Climate Change official tasked with overseeing the operation, Hugh Shaw, said the closure of the valves didn't mean the end of the operation.
"There will now be a period of extensive monitoring to determine whether the operation has been successful and whether the leak has been stemmed. This will be done through subsea surveillance as well as by aerial surveillance by government aircraft," said Shaw.
Shell said it has three vessels standing by the affected site with dispersants and specialized oil spill response equipment if needed.
The Marine Coastguard's latest estimate is that the sheen currently covers an area of 6.7 square kilometers and is 3.62 metric tons by volume. Initial environmental impact studies by Marine Scotland have showed no impact from the spill on local marine and bird life.
Shaw said the relevant U.K. authorities will be conducting an investigation. "A full report will, if appropriate, be sent to the Procurator Fiscal [public prosecutor]," said Shaw.
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