From: Associated Press
Published October 2, 2006 12:00 AM

BP Starts 'Pigging' Alaska Line

ANCHORAGE, Alaska — The shutdown of a satellite field on Alaska's North Slope will not stop BP PLC from beginning the process of cleaning out a corroded transit line in the nation's largest oil field.


"We're going to start a series of maintenance pigs this weekend," spokesman Steve Rinehart said Friday.


On Thursday, BP shut down a satellite Prudhoe Bay oil field after workers detected natural gas leaking into a manifold building, a key control facility. BP closed the Lisburne production center that processes crude oil and gas coming from the Lisburne field and the neighboring Point MacIntyre oil field.


The shutdown of Lisburne, a satellite field that feeds into the Prudhoe production stream, sent production down by 25,000 to 30,000 barrels per day, about 4 percent of North Slope output.


Methane gas from a high-pressure 14-inch pipeline somehow filled the unoccupied manifold building Thursday morning at Drill Site L2 along the shore of Prudhoe Bay, Rinehart said.


The gas had dissipated by late Thursday night.


"There's no estimate at this point of when production will return," Rinehart said. "We're kind of moving on two priority fronts: to complete the investigation and safely return to production."


The shutdown was a setback in what had been a gradually improving oil production picture since the eastern side of Prudhoe Bay ceased production Aug. 10, a few days after a leak was discovered in a corroded transit line.


The western side of the field kept producing after the company determined it could be operated safely. Its output is about 200,000 barrels a day.


For the last several days, BP had been restarting wells on the eastern side. And starting this weekend, the company will send a pig "that doesn't fit too tight" down a five-mile segment of the eastern transit line, Rinehart said.


In the following days, the size of the maintenance -- or cleaning -- pigs will become sequentially larger to clean out any deposits, allowing the smart pig to obtain good information about the condition of the inside of the pipe, Rinehart said.


The so-called smart pig uses ultrasound to check for thin spots in the pipeline.


Rinehart said the company anticipates it could take two weeks to complete the maintenance pigging process before the smart pig could be sent down the line.


Then it will take more time to analyze the data, he said. Meanwhile, the company continues to build a bypass line that could be used as a backup system.


Steve Marshall, the president of BP Exploration Alaska Inc., told a congressional hearing in early September that full Prudhoe Bay production could be restored by late October, but Rinehart on Friday declined to discuss a timetable.


BP eventually plans to replace two of three Prudhoe Bay transit lines because of corrosion, or about 16 of 22 miles of pipelines. BP expects to get replacement pipe by the end of the year with construction beginning early next year.


Prudhoe Bay and its satellites normally produce a combined 450,000 barrels per day. On Thursday, output stood at about 350,000 barrels.


BP runs Prudhoe, Lisburne and Point McIntyre on behalf of itself and other owners, including Exxon Mobil and Conoco Phillips.


Source: Associated Press


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