Why a natural gas storage climate ‘disaster’ could happen again

This story was originally published by Diffuse lighta non-profit newsroom that investigates the powerful interests blocking climate action.

On a November afternoon in 2022, a 57 year old stuff tapped at an underground natural gas storage reservoir in western Pennsylvania began leaking, fast enough that people a few miles away heard a loud, jet engine-like noise.

By the time the leak was stopped nearly two weeks later, about 16,000 metric tons of methane had escaped into the atmosphere, the equivalent of more than the annual greenhouse gas emissions from 300,000 gas-powered cars.

The blowout of a well at the Rager Mountain gas storage field was the worst methane leak from underground storage since Aliso Canyon in California in 2015. The incident forced thousands of people from their homes and sickened many, taking four months to recover. restrict. In 2021, 35,000 plaintiffs in one class action was awarded up to $1.5 billion in damages.

Although not as large or imminently dangerous to residents, the Rager Mountain leak was a “disaster,” according to one Pennsylvania regulator. Bloomberg labeled it as the United States’ worst climate disaster that year.

The natural gas that leaked methane in Pennsylvania and California is not stored in tanks, but in giant underground geologic formations accessible through various wells. There are about 400 such storage fields in 32 states.

According to a new report, there are thousands more potential opportunities for a similar situation across the country. The new analysis of data collected by federal regulators indicates that there are as many as 11,446 storage wells in the country with the same key risk as the wells that failed at Rager Mountain and Aliso Canyon: They have only a single barrier to failure.

“That population is much larger than we estimated, or what other state researchers have estimated [data],” said Greg Lackey, an author on the study and researcher at the Department of Energy’s National Energy Technology Laboratory.

All but one of Pennsylvania’s 49 gas storage fields have at least one potential single point of failure well, researchers found.

Natural gas consists primarily of methane, a greenhouse gas that is 80 times more potent than carbon dioxide in the short term. Methane leaks from oil and gas infrastructure are increasingly being investigated in the United States and worldwide, as stopping them is a relatively inexpensive and effective way to prevent greenhouse gas emissions, the primary cause of global warming.

Gas storage leaks are only one part of the industry’s methane problem. Such facilities are also at risk of dramatic blowouts that are difficult to control because they are connected to large, pressurized gas reservoirs.

New rules, fees aim to reduce methane leaks

Regulations imposed on gas storage post-Aliso Canyon continue to be rolled out, including a requirement for baseline risk assessments on all wells by 2027. New EPA rules on methane leaks and recovery and a planned federal fee on “waste” methane will also affect gas storage.

The fee, which is still being finalized, will eventually force companies to pay up to $1,500 per metric ton of methane more than the equivalent of 25,000 metric tons of carbon dioxide, a threshold that the Rager Mountain leak reaches nearly 20 times. Industry groups pushed back against the fee, arguing that it would disadvantage smaller oil and gas companies and discourage oil and gas production in general.

Many of these pits are decades old and not originally designed for storage. They went through the stress of repeated cycles of injection and withdrawal of gas. Some, like Rager Mountain, are in relatively rural, sparsely populated areas, but others are nearby neighborhoods in Pennsylvania, Ohio and California.

The Rager Mountain leak was caused by an underground fracture in one well’s casing – the barrier between where pressurized gas flows and the geology around it. According to a third party, the well became severely corroded due to exposure to water, air and organic matter through an open valve analysis submitted to regulators and obtained through a public records request.

“They probably didn’t realize it, but they created an optimal case for corrosion,” said Dan Arthur, president of engineering and technical services firm ALL Consulting, which reviewed the analysis.

Arthur says older wells in storage fields are not given “as much importance” as they should be, and operators need to make sure they pay full attention to well integrity.

“Age is a risk factor you have to consider, but it also depends on how you take care of the well,” he says. Redundant barriers reduce the risk of methane escaping if the well casing fails, Arthur and Lackey say.

Minimum federal safety standards on underground storage fields were set less than a decade ago in the wake of the Aliso Canyon leak. One of the federal agencies responsible for regulating gas storage sites, the Pipeline and Hazardous Materials Safety Administration (PHMSA), only began collecting regular data on underground storage fields in 2017.

More data is needed to identify the most risky wells

The number of wells with potentially only one barrier was three times larger than previously estimated before the PHMSA data became available, Lackey says. This “single point of failure” design that blows out in both Rager Mountain and Aliso Canyon is present in as many as 64 percent of all gas storage wells in the United States, his research found.

But the data reported to PHMSA isn’t enough to confirm how many of these wells actually have a single point of failure that would flag wells at highest risk of another blowout, Lackey says. Researchers will need more information about each well’s design and construction, he says.

“What you don’t get insight into is how many other casings there are, or where the locations of cement are,” Lackey says, describing additional barriers that will lower the risk.

Rager Mountain’s owner and operator, Equitrans, had its own risk ranking of storage pits, according to the third party analysis. While Rager is the company’s largest field in Pennsylvania, its wells were not ranked highest in the company’s own risk management plan — others were higher on the list because of their proximity to residential areas.

Both Peoples Natural Gas, the previous owner of the field, and Equitrans “recognized that corrosion was a problem,” so the companies used probes, known as “logs,” to examine the integrity of the well casings. But, the analysis noted, “Such a strategy is dependent on the log being reasonably accurate.”

A 2016 test of the casing wall of the well that ultimately failed underestimated its corrosion, the report said. When Equitrans ran the test again after the blowout with an updated algorithm, it showed much more corrosion.

In the wake of the Rager Mountain eruption, Pennsylvania’s Department of Environmental Protection said it was considering a “top-to-bottom review” of the state’s gas storage industry. Pennsylvania is one of a handful of states that have their own regulations covering gas storage.

“Everything is on the table for consideration in terms of making sure that this industry is appropriately regulated and the public is protected and the environment is protected from possible incidents like this happening again,” said Kurt Klapkowski, acting deputy secretary for DEP’s oil and gas management office, a month after the incident.

‘A large battery system’

But after a successful effort by Equitrans to shift the bulk of the incident investigation to federal regulators, DEP appears unsure or unable to move forward with such a review. Klapkowski told the agency’s Oil and Gas Council in September that regulators are “trying to figure out where our jurisdiction ends or can potentially be preempted by the federal government.”

Pennsylvania DEP’s investigation into surface and groundwater pollution at Rager Mountain is ongoing, the agency said in an emailed statement, and it “remains committed to its goal of inspecting storage field wells on an annual basis, regardless of risk.”

Wells are assessed through surface inspections and information reported by operators, DEP added, using several factors to prioritize wells for inspection, including the potential environmental impact and likelihood of failure, as well as proximity to the population.

Equitrans has taken several steps to reduce risk in its storage fields, spokeswoman Natalie Cox said in an emailed statement. These include reprocessing older well tests, conducting additional tests on 100 more wells in 2023, and changing the requirements for when to add protective gel to reduce corrosion. The company did not answer questions about whether these tests resulted in any well replacements.

Lackey’s study also found that nationally, while most leaks from gas storage were related to accidents or well improvement projects known as workovers, leaks from corrosion released a much larger volume of methane.

“If it’s a valve or something that’s broken off on the wellbore, it might be easier to contain that, rather than something in the hole that will be exposed to higher pressures in the well,” he says. “During repairs you have systems in place to contain the pit … whereas with corrosion it’s something silent in the background.”

While a 2016 government task force recommended phasing out single point of failure from wells, ultimately the federal minimum standards only require operators to address them by submitting risk management plans to federal regulators—plans that are not public.

The release of gas from Rager Mountain in November 2022 represented about 15 percent of the field’s working storage volume. Underground storage fields act as “a huge battery system,” says Drew Michanowicz, a researcher who has studied their proximity to residential areas.

Large leaks from storage not only release large volumes of greenhouse gases, but also reduce reliability in areas where natural gas dominates home heating and electricity production, Michanowicz says.

The federal leak investigation at Rager Mountain remains open at least until regulators review work to fix three temporarily plugged wells in the field, likely in the spring. But Rager Mountain works differently. In October, with PHMSA’s approval, Equitrans began injecting gas into the field for the winter.

This story was produced with support from the Fund for Investigative Journalism.