The explosion at a Chevron facility in Lost Hills Thursday afternoon destroyed a 5,000 bbl. tank and damaged two others.
Chevron officials say they have no immediate estimate of the damage.
"Chevron is still in the process of assessing the property damage and this will not be determined right away," Chevron Public Affairs Manager Carla Musser said.
She said a $10 million estimate from the Kern County Fire Department was premature.
There were no injuries.
The force of the explosion blew the lid from the large tank 150 feet, the Kern County Fire Department reported.
The explosion rocked the Chevron processing plant west of Lost Hills Road just south of the two of Lost Hills about 2 p.m.
Firefighters said it occurred in a large-diameter "wash tank" used to process oil.
The fire initially sent up a large column of black smoke but it was quickly extinguished.
Two other tanks were threatened for a time until the fire was knocked down.
About 40 firefighters responded to the incident in six engines, two ladder trucks and foam equipment.
No cause for the blast has been determined.