People try to get a look at the high surf along Beach Blvd as Hurricane Isaac passes through Gulfport, Mississippi, August 29, 2012. [Photo/Agencies]

Before moving to the Gulf Coast, Isaac killed at least 23 people and caused significant flooding and damage in Haiti and the Dominican Republic before skirting the southern tip of Florida on Sunday.

More than 700,000Louisianacustomers of Entergy Corp and other local utilities were without power as of late afternoon. Entergy warned that it would be unable to begin restoring power until winds drop below 30 mph (48 kph).

Oil production in the US Gulf of Mexico nearly ground to a halt as Isaac closed in on Louisiana on Tuesday and ports and coastal refineries curtailed operations.

But by Wednesday, big oil companies including Royal Dutch Shell and Exxon Mobil Corp began making plans to assess or restart operations.

Perceptions that the area's oil facilities would not sustain major damage left benchmark Brent crude settled on Wednesday down slightly, at $112.54 a barrel.