UPDATE 1-Hurricane Ida threatens Gulf of Mexico oil output

(Updates with Chevron shutting some output)

Nov 8 (Reuters) - Hurricane Ida Sunday posed the first real storm threat of the 2009 hurricane season to Gulf of Mexico oil and natural gas production.

The Gulf is the source of 25 percent of U.S. domestically produced oil and 15 percent of natural gas. About 40 percent of U.S. refining capacity is located on the Gulf Coast.

On Sunday night, the storm was located in the southern Gulf and expected to strike land by Tuesday somewhere between the states of Louisiana and Florida after roaring through the eastern Gulf oilfields over the next two days. here

-- IMPACTS OF IDA --

The Louisiana Offshore Oil Port (LOOP) said it was suspending offloading tankers in advance of the storm. [nN08202278]

BP Plc (BP.L), one of the Gulf's largest producers, said it had shut undisclosed amounts of production as a precaution and was evacuating some personnel. [nN08207106]

Marathon Oil Corp (MRO.N) said it had shut in Ewing Bank platform, which produces 11,700 barrels of oil per day and 10.5 million cubic feet of gas. [nN08196994]

Chevron Corp (CVX.N), another big producer, said it had shut some production while evacuating personnel.

Exxon Mobil Corp (XOM.N) said it was preparing to evacuate personnel, take other measures as necessary. [nN08202278]

Anadarko Petroleum Corp (APC.N) said it was evacuating personnel but had not shut production.

The U.S. Coast Guard said it was preparing for storm conditions and alerting mariners that the Port of Mobile, Alabama, could face gale force winds within 32 hours. (Reporting by Bruce Nichols)