Oil and gas operators in the Gulf of Mexico braced Friday for Tropical Storm Isaac as the strengthening storm barreled toward Haiti on a northwest track that threatened US offshore operations.
BP said it was evacuating its Thunder Horse platform, the world's largest offshore production and drilling facility.
"With forecasts indicating the storm could develop into a hurricane and enter the eastern side of the Gulf in coming days, we are taking additional steps to respond," the British oil giant said.
The facility has a capacity of 250,000 barrels per day of oil and 200 million cubic feet per day of natural gas.
The Gulf of Mexico is the hub of US offshore energy production, accounting for 23 percent of US crude oil output and 7.0 percent of US natural gas production.
The Gulf coast's facilities have more than 40 percent of total US petroleum refining capacity and 30 percent of natural gas processing plant capacity.
BP said it was moving non-essential staff out of harm's way from offshore facilities in Mississippi Canyon.
"Depending on the storm's path, it may be necessary to take additional measures to secure workers and operations at those sites," the company said.
Chevron also said it was evacuating non-essential staff from some offshore facilities in the Gulf but did not identify them.
Apache Corporation, based in Houston, Texas, said it was closely monitoring Isaac and had evacuated non-essential personnel in the eastern Gulf of Mexico.
Royal Dutch Shell said it was preparing for evacuations of non-essential personnel from platforms and had suspended some drilling operations.
Both Chevron and Shell said no production had been impacted.