Exxon Mobil said it was assessing storm damage to offshore facilities that it can get to safely.
"We are beginning the process of restoring operations at those facilities that can be safely restarted," a statement read. "Exxon Mobil Baton Rouge facilities continue operating at reduced rates and we are working to return to normal operations as soon as safely possible."
More than 80 percent of the production platforms in U.S. waters of the Gulf of Mexico were evacuated ahead of the storm. The effects of Isaac on the U.S. energy sector caused crude oil and gasoline prices to jump. Motor group AAA reported the national average for a gallon of gasoline continued to rise ahead of the holiday weekend in the United States.
Cinnamon Odell, a rig analyst at consultant company IHS, said most regional operators planned to return to production platforms in a phased process starting Friday.
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