Isaias shuts in more than 70% of US Gulf oil production

Hurricane Isaias has prompted operators to shut in about 1.46 million barrels of oil production per day in the US Gulf of Mexico. That represents 71.51% of the region's current daily output, according to the Marine Minerals Administration's October 9 update.

The estimate draws on reports from 12 companies as of 11 a.m. Central time. Workers were evacuated from 129 production platforms and eight drilling rigs. Natural gas production shut-ins reached 58.84%. A day earlier, oil shut-ins were estimated at about 1.3 million barrels per day.

The storm also poses refining risks. Lipow Oil Associates president Andy Lipow told CNBC that Chevron's potentially exposed Pascagoula, Mississippi, refinery and Vertex Energy's Saraland, Alabama, facility have combined capacity of 466,000 barrels per day, or 2.4% of US refining capacity. Those figures describe capacity at risk, rather than confirmed shutdowns at both plants.

Lipow identified power failures and flooding as the main threats. Restarting a refinery after a shutdown could take one to two weeks even without damage, he said. He estimated Gulf Coast refineries were operating at 95% capacity, leaving little spare capacity to replace lost output.

In a statement It was preparing to redeploy personnel and restore production. Operators must inspect facilities after the storm before restarting operations.

Lipow also warned of delays to tankers delivering crude and collecting gasoline, jet fuel and diesel. He said those disruptions could delay fuel deliveries to Florida. ClearView Energy Partners' Kevin Book told CNBC that refinery outages can raise fuel prices while reducing demand for crude oil.