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* BP evacuating some workers ahead of low-pressure system inUS Gulf
* Other oil producers monitoring weather
HOUSTON, Oct 2 (Reuters) - A looming low-pressure stormsystem prompted BP Plc to evacuate workers not essentialfor production from its four oil and gas platforms in the Gulfof Mexico but output was unaffected, the company said onWednesday.
Other operators, including Royal Dutch Shell, thebiggest oil producer in the Gulf, Anadarko Petroleum Corp and Hess Corp, said they were monitoring thestorm but had not begun evacuations.
A Pemex spokesperson said the company was closelymonitoring the forming storm, but it had not ordered anyoffshore or onshore evacuations at any installations.
The Mexican government said late on Wednesday it expectedbetween 3 to 6 inches (7.5 to 15 cm) of rain along its Yucatanpeninsula in addition to heavy rain in Gulf coast Veracruz andCampeche states, closer to the country's major oilinstallations.
The unnamed system had a 70 percent chance of becoming atropical cyclone in the next 48 hours and was expected to crossthe Yucatan and move into the southern Gulf by Thursday,according to the U.S. National Hurricane Center.
About 80 percent of Mexico's oil and gas production comesfrom mostly shallow-water offshore fields in the potential pathof the low pressure system, along the southern rim of the Gulf.
BP, the second-largest oil producer in the Gulf, saidworkers not essential to production, such as cooks and maids,were being evacuated from its four platforms in the mostenergy-infrastructure-heavy areas of the Gulf.
"With forecasts indicating the disturbance could possiblystrengthen into a tropical storm and move across the centralGulf of Mexico, we are now taking additional steps to respond,"the company said.
The four BP platforms have a total capacity of 640,000barrels per day of oil and 840 million cubic feet per day ofnatural gas. They include Thunder Horse, the largest oil and gasplatform in the world, as well as Atlantis, Na Kika and Mad Dog.
Mexico's government said the death toll from last month'stwin storms that pummeled both the Pacific and Gulf coasts nowstood at 157, with 8,000 people still housed in shelters.
