Oil companies scrambled out of the path of Tropical Storm Isaac, withdrawing offshore workers and cutting oil and gas production in the Gulf of Mexico.
By mid-day Sunday, the U.S. government said that daily oil production in the Gulf was down 24 percent and natural gas production was off 8 percent.
Isaac, already carrying winds of more than 60 miles an hour, was expected to cross the Florida Keys by late afternoon. The storm will likely pick up strength and strike as a dangerous Category 2 hurricane somewhere between New Orleans and the Florida Panhandle on Wednesday.
Noting that the storm was moving west and threatening to grow more powerful, energy giant BP evacuated all its installations and temporarily halted production in the Gulf Sunday.
The Bureau of Safety and Environmental Enforcement says 39 production platforms and eight drilling rigs have been evacuated as of Sunday. That's about 6.5 percent of the 596 manned platforms and 10.5 percent of the 76 rigs operating in the Gulf of Mexico.
Evacuation procedures include closing safety valves under the ocean floor to avoid pollution in case a rig or platform is damaged.