Shell says it has closed leaking North Sea valve

By the Associated Press | August 19, 2011 | 11:35 AM EDT

In this image released by Scotland's government marine surveillance agency on Tuesday Aug 17 2011, a sheen of leaked oil can be seen off the east coast of the country. Royal Dutch Shell has shut down the main leak at one of its North Sea oil rigs but struggled Tuesday to repair a secondary spill in a hard to reach part of the ocean floor. The company estimated Monday that 54,600 gallons of oil had spilled into the North Sea, and the leak was continuing at 5 barrels a day. At its largest point the oil sheen, or oil on the surface of the water, covered an area 19 miles wide by 2.7 miles long (31 kilometers by 4.3 kilometers). Most of it has now been dispersed by strong waves. The Gannet Alpha oil rig, 112 miles (180 kilometers) east of the city of Aberdeen, is operated by Shell and co-owned by Shell and Esso, a subsidiary of the U.S. oil firm Exxon Mobil.The BP spill in the Gulf of Mexico last year dumped 206 million gallons of oil. (AP Photo/ Marine Scotland)

LONDON (AP) — Royal Dutch Shell PLC said Friday it has closed a valve from which oil was spilling into the North Sea.

The company said this was a "key step" in stopping the leak at its Gannet Alpha platform, the worst North Sea oil spill in more than a decade.

Shell said it will now monitor the flowline to make sure the valve remains sealed.

Glen Cayley, technical director of Shell's exploration and production activities in Europe, said divers sealed off the valve in a "careful and complex operation."

"But we will be watching the line closely over the next 24 hours and beyond," he said.

"Our next task is to remove the residual oil from inside the depressurized flowline, and that will take time."

About 1,300 barrels of oil has spewed into the sea since a pipeline was found to be leaking Aug. 12, the company said, although it claimed that after is shut the well, only one barrel a day had been leaking from the installation to control the build-up of pressure in the pipeline.

The Maritime and Coastguard Agency said the spill, 110 miles (180 kilometers) east of Aberdeen, Scotland, has caused a sheen covering an area of 6.7 square kilometers (2.5 square miles).