Zombie Wells: the idle oil wells in Central California regulators say were leaking

FRESNO, Calif. (KFSN) -- Central California is home to thousands of oil and gas wells. Some have operated for decades, while others sit idle.

Idle wells have not produced oil in at least two years, and many have not been properly plugged.

"One of the big problems is that idle wells can leak," energy finance analyst Clark Williams-Derry said. "They can leak gasses like methane and some other gasses that can cause health and safety hazards to people who live nearby."

Energy analyst Clark Williams-Derry says there are more than 40,000 idle wells in California.

Action News set out to find some as part of a months-long ABC News investigation.

We went to Tulare County, just south of Porterville, where state records show at least ten oil wells in a roadside field.

Seen from the road, at least three appeared to be actively pumping for oil. Records reveal several others have been idle for years.

State regulators say idle wells should be permanently closed and sealed with a cement plug deep underground.

Estimates show it can cost more than $180,000 per well, so Williams-Derry says some operators turn to a cheaper alternative.

"In California, companies can essentially avoid plugging their wells by paying fees, and those fees allow for delay and allow companies to sort of kick the can down the road," Williams-Derry said.

The option is entirely legal. The well is not plugged with concrete underground, and the operator agrees to routine testing. As we found, leaks can happen.

State regulators visited another cluster of wells down the road from the field in Porterville. They wrote five violations for two wells that were actively leaking oil.

"It's not surprising at all that you were able to find leaking idle wells," Williams-Derry said. "I mean, it's really fairly common."

In some places, leaking oil wells are called "zombie wells."

ABC News and affiliate stations conducted their own testing at 76 wells in five states. At the time, more than half were leaking oil or combustible gas.

Fresno State Earth and Environmental Sciences professor Christopher Pluhar says methane is one of the gases that often leak from idle wells, "Methane is 30 times more effective at trapping heat in Earth's atmosphere than carbon dioxide."

It is impossible to know if the oil wells we saw in Tulare County are causing environmental or health issues, but the state's website for idle wells lays out the possible risks in the first paragraph.

The website states, "If a well is not properly sealed and closed, it may provide a pathway for hydrocarbons or other contaminants to migrate into drinking water or to the surface.

"There are cases where people who live near idle oil and gas wells that are leaking, who experience headaches or other health problems that they attribute at least to the presence of leaking wells very near their homes," Williams-Derry said.

The American Petroleum Institute is a trade association representing oil and natural gas companies.

In a statement to ABC News, an API spokesperson said, in part, "The proper sealing of oil and natural gas wells is paramount to ensure safety, sustainability and environmental protection ... API has established strong industry standards to advance the permanent closure and remediation of historic wells in accordance with applicable federal and state laws."

With more wells left idle as California's oil production slows, Williams-Derry says there should be firm deadlines for plugging wells, mandates that companies save more money for cleanup, and reformed regulations.

"We need to have better funding for regulators to test wells," Williams-Derry said. "We need to have better funding for regulators to make sure that they're enforcing the law, and we also need to hold the feet to the fire and not let companies off the hook."

A new law recently signed by Governor Gavin Newsom increased the fees well operators must pay for their idle wells. The fees range from $1,000 to $60,000 per well per year.

Overall, paying the fees is still much cheaper than the average $180,000 cost to plug a well, leading experts and environmental groups to say there is still more work.

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