A Leaky Mystery Beneath Montana’s Orphan Wells

USGS monitoring shows methane from orphaned wells can shift fourfold within hours, complicating federal efforts to rank which sites to plug first

13 Mar 2026

Methane leaking from orphaned oil and gas wells may be far less predictable than regulators hoped. New research from the U.S. Geological Survey found emissions can rise or fall sharply within just a few hours, a wrinkle that could scramble how the government decides which wells pose the biggest climate risk.

The study, published in 2026 in Science of the Total Environment, tracked 15 leaking orphaned wells in northern Montana’s Kevin-Sunburst Dome. Instead of relying on the one-off measurements common in field surveys, researchers monitored wells continuously for as long as 452 hours.

What they found was hard to ignore. Changes in wind and daily temperature pushed methane emissions up or down by as much as fourfold in a matter of hours. Across the 15 wells, emissions ranged from undetectable to 2.7 kilograms per hour, while the average leaking well released 211 grams per hour.

Some wells spiked at the same time, suggesting weather was driving a shared response. Others acted like they were on their own schedule, even though they tapped the same reservoir and sat only a few hundred meters apart. That kind of uneven behavior makes a quick snapshot look a lot less reliable.

The policy stakes are high. The Department of the Interior is spending $4.7 billion from the Bipartisan Infrastructure Law to plug orphaned wells across 27 states, with methane measurements helping shape the priority list.

That system works only if the measurements capture reality. A well checked on a breezy afternoon might look tame, while the same well on a calm morning could rank as a much bigger emitter. In practice, that means some of the worst wells could slip down the list while lower-risk sites move ahead.

Earlier USGS work showed that roughly 10 percent of orphaned wells produce most detectable methane emissions nationwide. This new study adds an uncomfortable twist: finding that top tier may be harder than anyone thought.

As plugging efforts grow and carbon markets demand credible emissions data, the case for better monitoring is getting stronger. The Montana study makes one point clear: when weather can reshape the numbers by the hour, a single reading may tell only part of the story.