Tropical Storm Rita churned toward the Gulf and threatened to compound the damage left last month by Hurricane Katrina.
BP was removing workers from platforms near the Alabama coast and in the deep water central Gulf Monday and will decide in coming days whether to evacuate from the western Gulf.
Shell Oil has removed 195 non-essential employees and plans to remove about 350 more, beginning with easternmost platforms.
Chevron didn't disclose the number of employees and contractors it evacuated. It removed 2,100 workers ahead of Hurricane Katrina.
Marathon Oil is evacuating 40 people doing repair work on three platforms damaged by Katrina.
Other companies with operations in the Gulf are watching the storm's track.