Exxon Mobil is making progress restarting the nation's second largest refinery in the wake of Hurricane Harvey and is preparing to keep Florida supplied with gasoline as Hurricane Irma takes aim, Exxon CEO and Chairman Darren Woods told CNBC.
Flooding and other damage caused by Harvey temporarily cut about 20 to 25 percent of U.S. refining capacity. That included Exxon's massive Baytown, Texas, refinery, which closed last week due to operational issues caused by flooding.
The oil giant began the restart process on Friday at the refinery, which processes 585,000 barrels a day. Refiners must gradually resume operations to avoid damaging equipment.
"It's very difficult to predict exactly when all those units will be back up and we'll be back on our full load. But we're making good progress. We're hoping to get some units started up later this week, and then it will be one unit after another," Woods said in an interview that aired Thursday on CNBC's "Squawk Box."
That process will continue over "the next several weeks," he said. Woods confirmed that there were "significant impacts" and "lots of flooding" at Baytown. Exxon's Beaumont, Texas, refinery, which processes 363,000 barrels a day, remained offline due to flooding, though the company restarted operations at its Beaumont chemical manufacturing complex by Sunday.
The Gulf Coast is the center of the U.S. petrochemicals and specialty chemicals industry. Harvey knocked out about 60 percent of base plastics manufacturing.
Exxon has not yet assessed Harvey's impact on third-quarter earnings, Woods said, but he sought to assure investors that the storm would not affect Exxon's capital spending plans.
"We're working through what the financial impacts of that will be, and as we get further along in this recovery process we'll have a better read of that," he said.
Part of Exxon's Harvey response team is now planning for Hurricane Irma, a rare Category 5 hurricane that could make landfall in Florida this weekend.
Exxon is focusing on its distribution system in Florida, making sure its fuel inventories are high enough throughout the state to supply motorists once the storm passes. The uncertain path of Irma led to a statewide run on gasoline that has made it difficult for distributors to restock gasoline stations.
"We're not trying to second guess where that storm will be. Instead we're trying to be prepared across the board so that irrespective of where it lands, we've got fuel where we're going to need it," Woods said.
Exxon Mobil does not expect Irma to affect its offshore Gulf of Mexico oil production operations, Woods said. Operations that Exxon temporarily shut down as Harvey blew through the gulf are restarting, he added.
The company has committed $9.5 million to Harvey relief efforts.