The federal government says oil and gas operators continue to evacuate offshore platforms and rigs in Tropical Storm Isaac's likely path through the Gulf of Mexico.
Isaac is expected to become a Category 2 hurricane before making landfall Wednesday.
The Bureau of Safety and Environmental Enforcement says 39 production platforms and eight drilling rigs have been evacuated. 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.
The bureau says operators estimate that about 24 percent of the current daily oil production and 8 percent of natural gas production has been cut off.
Rig evacuations began Friday.