Methane leaks plague oil and gas wells in New Mexico

Startling amounts of methane are leaking from wells and pipelines in New Mexico, according to a new analysis of air data, suggesting the oil and gas industry may be contributing more to climate change than previously realized.

The study by Stanford University researchers estimates that oil and gas operations in New Mexico’s Permian Basin release 194 tons per hour of methane, a gas that warms the planet and is many times more potent than carbon dioxide. That’s more than six times the most recent estimate from the Environmental Protection Agency.

The number came as a surprise to Yuanlei Chen and Evan Sherwin, lead authors of the study, published Wednesday in the journal Environmental Science & Technology.

“We’ve really spent the last two-plus years going back and forth thinking about how we could be wrong and talking to other experts in the methane community,” said Dr. Sherwin, a postdoctoral researcher in energy resource engineering at Stanford. “And at the end of that process, we realized that that was our best estimate of methane emissions in that region and at that point in time, and we had to make it public.”

He and Ms. Chen, a Ph.D. Energy Resources Engineering student, said their results showed the need to survey a large number of sites to accurately measure the environmental impact of oil and gas exploration.

The largest previous assessment of methane emissions from oil and gas in the United States, released in 2018, reviewed studies covering about 1,000 wells, a tiny fraction of the more than 1 million active wells in the country. The new study, on the other hand, used aerial imagery to survey nearly 27,000 sites from above: more than 90 percent of all wells in the New Mexico portion of the Permian Basin, which also extends into Texas.

Researchers also took multiple measurements at each site to account for the fact that operations, and therefore emissions, change over time. Methane can be released from wells both intentionally in a process known as venting, and through accidental leaks from aging or failing equipment.

They found that a small number of wells and pipelines were responsible for “the vast majority” of the methane leaks, Ms. Chen said, adding, “Comprehensive investigations of point sources find more momentous emission events driving overall emissions.”

Robert Howarth, a professor of ecology and environmental biology at Cornell University, who was not involved in the study, called it “very carefully done.” dr Howarth has long argued that the EPA is grossly underestimating the methane problem. The new study calculated methane emissions as 9.4 percent of gross gas production, dwarfing the Environmental Protection Agency’s estimate of 1.4 percent.

Natural gas accounts for about a third of America’s energy use, and because it’s less costly than coal in terms of carbon emissions, many policymakers have touted it as a “bridge” that could do less harm to the climate while society works to make the longer-term transition renewable energies. But compared to coal, natural gas results in much higher emissions of methane, which is a more potent greenhouse gas than carbon dioxide but doesn’t stay in the atmosphere for as long.

Ramón Alvarez, an atmospheric chemist at the Environmental Defense Fund, estimated about a decade ago that the break-even point — the point above which natural gas would actually do more harm to the climate than coal — was at a 3.1 percent methane leak rate. Based on recent data from the Intergovernmental Panel on Climate Change, Dr. Howarth that the threshold is closer to 2.8 or 2.9 percent.

That makes the 9.4 percent leakage rate in the new study highly alarming, experts said, although they stressed the rate in the Permian Basin may not be comparable to rates elsewhere.

“If this result is similar in other basins — which we don’t know — it would negate the greenhouse gas emissions savings from the transition from coal to gas,” said Amy Townsend-Small, associate professor of environmental sciences at the University of Cincinnati.

If there was good news in the study, it was that a small number of oil and gas sites contributed disproportionately to emissions – suggesting it’s possible for the industry to operate cleaner if the worst offenders change their practices to change.

A rule passed by the New Mexico Oil Conservation Commission last year bans regular venting and flaring, referring to the practice of releasing or burning natural gas rather than containing it. Another regulation being considered by the state’s Environmental Improvement Board would require more frequent inspections and repairs to oil and gas infrastructure. (This measure is intended to reduce emissions of volatile organic compounds, a group of chemicals that can have adverse health effects, but oil and gas sites that leach VOCs also tend to leach methane.)

The Stanford researchers emphasized that the same methodology they used to quantify methane emissions could be used to identify problem spots and introduce regulations accordingly.

“Air engineering has identified high methane emissions,” Ms. Chen said, “but can also help fix them cost-effectively.”

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