Chevron Corp CVX.N extinguished a fire early on Wednesday at its 245,000 barrel-per-day (bpd) refinery in Richmond, California, the company said in a statement.
"While preparing a non-operational area for maintenance work using a specialized hose and steam, a leak and small fire occurred which was extinguished at 2:59 a.m.," Chevron said in an e-mailed statement. "While our investigation into the incident is continuing, there is no indication that the leak occurred from a pipe or a processing line."
The impact on operations is still being assessed, according to a person familiar with the plant's operations. The person also said the fire occurred in the area of the fluid catalytic cracker, a main gasoline-producing unit, but was not inside the unit.
The discount for wholesale gasoline in the Los Angeles area narrowed 5 cents to 5 cents below the August NYMEX contract for RBOB gasoline futures. Market participants attributed the move to the fire at Richmond, and said the fire might have been on a pipeline carrying heavy cycle oil from the plant's fluid catalytic cracking unit.
The prices rose despite a small build in inventories on the West Coast as reported by EIA earlier on Wednesday.
There were no injuries due to the fire.
A massive fire at the refinery in August 2012 sent a plume of smoke over Richmond, a densely populated industrial suburb of San Francisco, leading to thousands of people being sent to hospital emergency rooms. It also caused a prolonged outage which affected local gasoline prices.
Any lengthy disruption in production at the third-largest refinery in California could affect the supply of fuel on the U.S. West Coast, particularly gasoline, due to the difficulty in meeting California's super-clean specifications. The region also has few immediate sources of alternative supply.
Chevron's proposal to upgrade the refinery to broaden its fuel slate is currently under review by the Richmond City Council.
(Reporting by Ratul Ray Chaudhuri and Koustav Samanta in Bangalore and by Erwin Seba in Houston; editing by Jessica Resnick-Ault, G Crosse, Bernadette Baum and Diane Craft)