A "low rate" flow of oil and water resumed Wednesday at Chevron's months-old Cymric Oil Field leak near McKittrick, the company said Thursday.
A company spokesman said by email he was unable to estimate how much black fluid is coming out of the ground at the site, which has already released hundreds of thousands of gallons since it was first reported in May.
"We are working to determine the source of the flow, but believe it could be residual fluid from the previous seep occurrence," spokesman Jonathan Harshman wrote. "We are taking actions to stop the flow and are working with the appropriate regulatory agencies."
Resumption of the flow came five days after the California Division of Oil, Gas and Geothermal Resources ordered Chevron to "take all measures" to prevent the leak from starting again.
The company has provided DOGGR with a report on what appears to have caused the leak, but the agency rejected the document as inadequate.
On state orders, Chevron stopped steam injection within 1,000 feet of the abandoned well believed to be at fault. About 20 injection wells in the area have been shut down, while nine idle production wells have been reactivated as a way of reducing underground pressure.
Steam is used in the Cymric field to heat oil in the area as part of the production process called cyclic steaming.
Surface expression, as the leaking phenomenon is called, can result when high-pressure steam escapes beyond target pathways. When the steam escapes, it comes up with a mix of oil and water.