By Ernest Scheyder and Marianna Parraga
HOUSTON (Reuters) - Oil and natural gas producers began evacuating staff at U.S. Gulf of Mexico platforms on Thursday ahead of Tropical Storm Nate, the second storm in as many months to threaten Gulf Coast oil and refining facilities.
Nate, which has already killed three people in Costa Rica, according to local authorities, is forecast to scrape past Honduras and Mexico, enter the Gulf and strengthen into a hurricane before making landfall early on Sunday in Louisiana, near several major refineries.
That path takes it through an area populated by offshore oil and natural gas platforms, which pumps more than 1.6 million barrels of crude per day, about 17 percent of U.S. output, according to government data.
Forecasts for Nate have shifted in the past 24 hours. The National Hurricane Center (NHC) had forecast on Wednesday that the storm would make landfall in the Florida panhandle.
Chevron Corp, Exxon Mobil Corp, Royal Dutch Shell Plc and others have begun withdrawing personnel from Gulf platforms.
Marathon Oil Corp and ConocoPhillips said they were monitoring Nate's path but have taken no action yet.
Nate, the 14th named storm of the Atlantic hurricane season, comes less than two months after Hurricane Harvey tore through the Gulf, denting more than a quarter of oil production there, according to government data.
Several Texas ports have been unable to allow large tankers to return after Harvey as they wait for dredging of channels. Some large tankers have been re-routed to Louisiana ports, some of which are now in Nate's projected path.
The Louisiana Offshore Oil Port (LOOP), an offshore gathering hub for production platforms and crude imports from tankers, has not suspended operations and vessel activity around it continues as normal, officials said.
All Louisiana ports were open and fully working on Thursday as authorities and the U.S. Coast Guard monitor the storm, according to the Port Association of Louisiana.
"We are used to these type of things, so we have a hurricane plan we have put in place as we continue to monitor the storm," said Bill Rase, director of the Lake Charles port, which operated with restrictions after Harvey until Tuesday.
Refiners in Louisiana also have been scrambling ahead of Nate. At least three Louisiana refineries were preparing to continue operation through Nate, sources familiar with plant operations said on Thursday.
PBF Energy's Chalmette, Louisiana, refinery and Shell's refineries in Convent and Norco, Louisiana, were preparing for the storm, but planned to remain in operation, the sources said.
A PBF spokesman declined to discuss operations at the Chalmette refinery. A Shell spokesman was not available to comment.
Chevron said its Pascagoula, Mississippi, refinery was monitoring the storm's progress. Exxon said the same about its refinery and chemical plant in Baton Rouge, Louisiana.
A Marathon Petroleum Corp spokesman declined to discuss operations at the company’s Garyville, Louisiana, refinery.
(Reporting by Ernest Scheyder and Marianna Parraga; Additional reporting by Erwin Seba and Bryan Sims in Houston and Enrique Andres Pretel in San Jose, Costa Rica; Editing by Susan Thomas)