Nov. 9 (Bloomberg) -- Oil companies in the Gulf of Mexico are evacuating workers and halting some output as Hurricane Ida blows through the region, which accounts for more than a quarter of U.S. crude production.

BP Plc evacuated non-essential staff and shut some of its Gulf output. “Some precautionary curtailment of production has taken place,” BP said in a recorded statement on its hotline. Ida is the first storm to disrupt output in the Gulf this hurricane season, which runs from June to November.

Chevron Corp., the second-largest U.S. oil company, has also halted “some production” at its Gulf of Mexico platforms, according to its Web site. The company moved some non-essential workers out of the area, spokesman Mickey Driver said yesterday.

Crude oil for December delivery climbed for the first time in three days, gaining as much as $1.52, or 2 percent, to $78.95 a barrel on the New York Mercantile Exchange.

Ida’s maximum sustained winds slowed to about 80 miles (130 kilometers) per hour, from 105 mph earlier today, the U.S. National Hurricane Center said in its latest advisory. Ida’s center was located about 235 miles south-southeast of the mouth of the Mississippi River at 6 a.m. U.S. Central time, it said.

Storm’s Direction

The Category 1 storm was moving north-northwest at 16 mph and may still be at hurricane strength when it approaches the U.S. Gulf Coast near Alabama and the Florida Panhandle in the early hours of tomorrow morning.

Exxon Mobil Corp., the world’s biggest oil company, said its operations in the Gulf of Mexico are normal and it’s monitoring the weather, according to an e-mail from spokesman David Eglinton. Royal Dutch Shell Plc said it’s “securing” offshore facilities though drilling isn’t affected.

About 80 percent of Shell’s U.S. oil and gas production comes from the Gulf of Mexico, the company said on its Web site.

The Gulf accounts for about 27 percent of U.S. oil production and 15 percent of gas output, according to Energy Department figures. Fuel prices rose to a record in 2005 after Hurricane Katrina decimated platforms, pipelines and refineries on the Mississippi and Louisiana coasts.

A hurricane warning, meaning hurricane conditions are expected within 24 hours, is in effect from Pascagoula, Mississippi, to Indian Pass, Florida, the agency said. It doesn’t include the city of New Orleans.

Coastal Refineries

Chevron Corp. operates a 330,000 barrel-a-day oil refinery at Pascagoula. Refinery shutdowns sometimes occur when strong winds knock down power lines. Should the storm shift further west, several more refineries in Louisiana may be subject to heavy rain, winds or possible flooding.

Hurricane conditions are also “possible” within a broader “watch” area that stretches from Grand Isle, Louisiana, eastward to Pascagoula.

The Louisiana Offshore Oil Port stopped loadings from tankers at about noon local time yesterday because of rough seas as a result of the approach of the hurricane, Barb Hestermann, a spokeswoman, said in a phone interview.

“Customers are still getting deliveries,” she said, adding that supplies to refineries are being made from onshore storage tanks. “It seems that Monday and Tuesday will be pretty bad.”

Anadarko Petroleum Corp., the second-largest producer of natural gas in the U.S., evacuated workers and secured some facilities in the Eastern Gulf of Mexico, the company said on its Web site. No production has been shut, the company said in a statement yesterday.

To contact the reporters on this story: Christian Schmollinger in Singapore at christian.s@bloomberg.net; Ann Koh in Singapore at akoh15@bloomberg.net.

Last Updated: November 9, 2009 07:52 EST