Several thousand contractors will be on site in March and April to perform maintenance at Chevron's Pascagoula Refinery.
"These are scheduled maintenance turnarounds that we're doing and there are several units that will be involved," said Alan Sudduth, manager of public and governmental affairs at the refinery.
He declined to provide specific information about what maintenance work will be done on which units but said the work is expected to take 3 to 4 months.
"We should be completed with our turnarounds by the second quarter," he said.
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Employees will continue to work while the maintenance is under way, and Sudduth said if there is any adjustment to the schedule there's going to be more hours for the staff, not less.
The Pascagoula facility is Chevron's largest wholly-owned refinery. It processes 330,000 barrels, or 13.9 million gallons, of crude oil a day, which according to the company website is equivalent to the size of a football field covered 40 feet deep.
Even with the units being temporarily offline, Sudduth said the refinery will stay at the same production level over the course of the year.
"It doesn't impact our ability to provide product to the customer as scheduled," he said of the maintenance.
Refineries generally do maintenance turnarounds during fall and late winter when demand is weaker, said Patrick DeHaan, senior petroleum analyst with GasBuddy.com.
Sudduth said Chevron has many process units at the plant and all are under a scheduled maintenance program.
Last week Chevron reported a fourth quarter loss of $0.31 per share as oil continues to sell for about $30 a barrel.
The price of crude oil has more of a negative impact on the upstream side of the business, or exploration and getting the crude out of the ground, he said, than the downstream side of processing the product.
Sudduth said while the local refinery is sensitive to the market, "We are adding value to business by running as efficiently and safely as we can right now."