(CNN) – About a quarter of the oil produced in the Gulf of Mexico was shut down as of Saturday, according to the Interior Department’s Bureau of Safety and Environmental Enforcement. That amounts to nearly 430,000 barrels of oil per day.

The bureau also estimated that about 26% of natural gas production in the Gulf has been shut in. Federal officials are expected to have an update around 2 p.m. ET Sunday.
Harvey made landfall as a Category 4 hurricane late Friday, but was downgraded to a tropical storm by mid-Saturday. But it continued to dump huge amounts of rain on Houston and cause dangerous flooding that could get worse.
The area is home to nearly one-third of the nation’s capacity to turn oil into gas, diesel and other products. Federal officials said Saturday that workers from 112 oil and gas production platforms had been evacuated. All told, 737 platforms in the Gulf are staffed with workers.

Related: Harvey could hit the Texas economy

Harvey is the first major storm to seriously threaten the Gulf Coast energy sector in awhile.

Hurricanes Gustav and Ike in 2008, as well as Hurricane Isaac in 2012, all knocked more than 1 million barrels of Gulf oil production offline, according to the EIA. Those hurricanes also temporarily disrupted refining capacity.

Hurricanes that land in Texas tend to have little impact on oil production, but more significant consequences for refining, according to Tom Kloza, chief oil analyst at the Oil Price Information Service.

Earlier forecasts showed Harvey staying clear of refineries in the Houston area, but the storm still threatened plants in the Corpus Christi region.

Harvey forced about 900,000 barrels per day of the state’s refining capacity to shut down, mostly around Corpus Christi, according to S&P Global Platts.

That included a Valero Energy (VLO) plant that produced 293,000 barrels per day, as well as a Citgo refinery that produced 157,500 barrels.

Valero Energy reported Sunday that there were no “substantial refinery impacts” because of the storm. The company said it is working with government officials to figure out what it needs to do to resume operations.

Exxon Mobil (XOM) on Sunday said it was in the process of shutting down its Baytown campus, one of the largest refining complexes in the U.S. The refinery can produce up to 584,000 barrels of crude oil per day.Related: Impact Your World – How you can help Harvey’s victims

Houston also marks the beginning of the Colonial Pipeline, which transports more than 100 million gallons of gasoline, heating oil and aviation fuel each day to as far as the New York harbor. Power outages during Hurricanes Katrina and Rita in 2005 forced the shutdown of parts of the Colonial Pipeline for several days.

Kloza said that normally refining is knocked offline for just a brief time, making the impact on prices fleeting. But that depends on the severity of the storm.

“Katrina was the exception,” Kloza said, referring to the 2005 storm that badly damaged Gulf Coast operations.

He predicted on Thursday that Harvey is likely to cause only a short-term jump in gas prices of 5 to 10 cents per gallon, though he said a 25-cent spike in a worst-case scenario was also possible.

The average price of a gallon of regular gasoline nationwide has ticked up a few cents in recent days, according to AAA.

“You’re talking about a situation where a month from now gas prices will probably be lower. But a week from now they’ll be higher,” said Kloza.