BP (www.bp.com) has begun a phased shutdown of its Prudhoe Bay oilfield following the discovery of unexpectedly severe corrosion and a small spill from a Prudhoe Bay oil transit line. Shutting down the field will take several days to complete, according to BP, and it will reduce Alaska North Slope oil production by an estimated 400,000 barrels per day.

The decision follows the receipt on Friday of data from a smart pig run completed in late July. Analysis of the data revealed 16 anomalies in 12 locations in an oil transit line on the eastern side of the oil field.

In response to the inspection data, BP conducted follow-up inspections of anomalies where corrosion-related wall thinning appeared to exceed BP criteria for continued operation. It was during these follow-up inspections that BP personnel discovered a leak and small spill estimated at four to five barrels.

The spill has been contained and a clean-up effort is underway, according to BP. The pipeline was shutdown at 6:30 am Sunday morning. BP has notified state and federal officials of the decision to shut down the oil field.

“We regret that it is necessary to take this action and we apologize to the nation and the State of Alaska for the adverse impacts it will cause,” said BP America Chairman and President, Bob Malone, in a prepared statement. “However, the discovery of this leak and the unexpected results of this most recent smart pig run have called into question the condition of the oil transit lines at Prudhoe Bay. We will not resume operation of the field until we and government regulators are satisfied that they can be operated safely and pose no threat to the environment.”

BP is identifying and mobilizing additional resources from across Alaska and North America in order to speed inspection of remaining Prudhoe Bay oil transit lines. BP operates 22 miles of oil transit pipeline at Prudhoe Bay. Smart pigging inspection has been completed over about 40 percent of that length.

BP previously announced plans to replace a three-mile segment of pipeline following inspections conducted after a large spill discovered on March 2, 2006.