Production at the Prudhoe Bay oil field was reduced by another 90,000 barrels when a problem was discovered in a compressor, according to a spokesman for BP PLC, operator of the oil field.
The mechanical problem cut oil production on Wednesday at Prudhoe Bay from an already reduced 200,000 barrels to 110,000 barrels, said BP Alaska spokesman Daren Beaudo. It likely would take several days to complete the repairs, he said.
The compressor that failed handles natural gas that is produced with the oil and water during the processing of crude. Only the western side of the field is producing oil following the shutdown of the eastern half earlier this month.
In a separate event, work to remove insulation from a transit line on the western side of the field was temporarily halted on Wednesday. BP wants time to evaluate the potential for workers to be exposed to materials that contain between 5 percent and 10 percent asbestos before continuing the work, Beaudo said.
The insulating material was applied when the line was originally installed in the late 1970s.
Beaudo said that the line would continue to operate while BP assesses how to safely handle the material.
The Prudhoe Bay field had been producing about 400,000 barrels a day of oil when workers Aug. 6 discovered a leak in a transit line on the eastern side of the field.
The leak, which spilled about 757 liters of oil, was found while workers stripped off insulation to get a better look at the line after a test indicated numerous areas where the pipe wall was exceptionally thin. The problem has since been blamed on bacterial corrosion that created pitting in the pipe.
The company plans to replace 26km of corroded transit pipes.
It was the second leak found in a transit line which transport oil to the trans-Alaska pipeline. In March, a leak in a corroded transit line pipe resulted in the spill of more than 757,000 liters of crude -- the largest spill ever on the North Slope. A bypass was put on that line to keep it operating.