Inactive Oil and Gas Wells Leaking Microbial Methane at 1,000x Estimated Rates
A new study led by researchers at McGill University has uncovered a significant environmental blind spot, revealing that microbial methane leaking from non-producing oil and gas wells is being emitted at rates approximately 1,000 times higher than previous estimates. This discovery suggests that inactive wells may remain active sources of potent greenhouse gases long after their primary resources have been exhausted.
The research team analyzed 401 non-producing wells across Canada, with more than 90% of the sampled sites located in Western Canada. For the purposes of the study, “non-producing wells” included those that have ceased production, remained inactive, or never produced gas or oil in the first place.
“Methane is a powerful greenhouse gas when released into the atmosphere, regardless of its origin. In particular, this study implies that non-producing oil and gas wells could continue to emit microbial methane long after the targeted formation has been fully depleted,” said Mary Kang, study co-author and Associate Professor of Civil Engineering.
The findings highlight a widespread issue across the Canadian landscape, which hosts nearly 500,000 non-producing wells. While not every well is a source of leakage, the prevalence of microbial methane was far higher than expected. The team detected microbial methane in 23% of the sampled wells—roughly three times the previous estimates—and found traces of the gas in an additional 50% of the sites.
Identifying the exact origin of these emissions remains a technical challenge. According to Kang, the subsurface is a complex system featuring multiple gas-bearing formations, which often obscures the precise source of the methane.
The data also points to a “super-emitter” phenomenon. Referencing previous research by the same team, the study noted that a small fraction of wells—the top 12% of emitters—are responsible for a staggering 98% of the total emissions from this source. This concentration of leakage suggests that targeted mitigation strategies could have a disproportionately high impact on reducing overall methane output.
This discovery underscores the critical need for improved monitoring and management of legacy energy infrastructure to better combat climate change. Understanding the biological and geological drivers of these emissions is essential for developing more effective mitigation technologies.
