image: A global map visualizes over 4.5 million abandoned oil and gas wells, highlighting methane emission hotspots across North America, Europe, and Southeast Asia. High-emitting “super-emitter” wells—often located in offshore shallow waters—are marked as critical targets for early mitigation. Art by Tianyang Lei.
Credit: Art by Tianyang Lei.
This study is led by Professor Dabo Guan (Tsinghua University) and Dr. Tianyang Lei (University College London). It presents the first global-scale inventory of methane emissions from abandoned oil and gas (AOG) wells, covering 4.5 million abandoned wells across 127 countries. Among them, 420,000 wells with detailed records were used to develop a high-resolution emissions model based on geographic, geological, and management attributes.
“This is the first time the world has a comprehensive map of where these forgotten wells are, how much methane they release, and what we can do about it,” says Dr. Tianyang Lei, lead author of the study. “Many of these wells have been leaking unnoticed for decades.”
The team estimate that in 2022 alone, AOG wells released approximately 400,000 tonnes of methane, with more than 90% of these emissions originating from unplugged wells. Ten countries account for 98% of the global total, and the United States alone contributes nearly 70%. Particularly concerning are “super-emitter” wells—those emitting more than 1.6 tonnes of methane annually—found primarily in shallow offshore regions such as the North Sea, West Africa, and Southeast Asia, where emissions can be up to 11 times higher than onshore wells due to easier gas transfer from water to air.
“Methane in these nearshore regions doesn’t have much time to dissolve in water—it goes straight up into the air,” says Dr. Lei. “That makes even a small number of wells disproportionately important for short-term climate impacts.”
Beyond current emissions, the researchers also estimated the historica release of methane from abandoned wells, dating back decades. Using the detailed sample of 420,000 wells, they extrapolated global cumulative emissions to be in the range of 11.2 to 12.6 million tonnes of methane as of 2022. These emissions occurred gradually, often undetected and unrecorded in official greenhouse gas inventories.
“Methane is short-lived in the atmosphere—only about a decade—but its warming power is intense,” explains Prof. Dabo Guan. “That’s why sustained emissions from sources like abandoned wells matter: they can maintain a persistent near-term warming pressure that is often overlooked in official inventories and policy frameworks.”
The study also sheds light on the legacy responsibilities of former well operators. Researchers traced historical ownership data and found that just six international oil and gas companies are associated with approximately 10% of global cumulative emissions from abandoned wells. For instance, Shell’s legacy wells account for 28% of Indonesia’s and 22% of Nigeria’s estimated AOG well emissions. Chevron’s former assets contribute 42% of Thailand’s emissions from this category.
“It’s a powerful reminder that climate responsibility doesn’t end when production stops,” says Prof. Guan. “Many of these wells were drilled decades ago, but the emissions are still with us today—and they’re still avoidable.”
To assess mitigation opportunities, the team simulated three scenarios for well-plugging strategies: baseline closure schedules, delayed plugging (by 3 years), and accelerated plugging (3 years earlier). The results are striking: up to 61% of methane emissions from AOG wells between 2023 and 2050 could be avoided through early intervention, representing a savings of approximately 1.6 million tonnes of methane.
“Because methane is a short-lived climate forcer, reductions today translate almost immediately into climate benefit,” says Dr. Lei. “Few climate actions offer that kind of near-term return.”
A key insight from the study is the average 22-year delay between a well’s deactivation and its eventual plugging. During this window, methane continues to escape into the atmosphere. Given methane’s 80+ times greater warming potential than CO₂ over 20 years, these unmonitored emissions are disproportionately harmful to short-term climate goals.
“We’re in a decade that demands fast-acting mitigation,” Prof. Guan emphasizes. “If we want to slow warming quickly, methane is the lever—and abandoned wells are a place we can pull that lever right now.”
The study urges countries to prioritize high-risk wells—particularly those that are older, unplugged, offshore, or gas-bearing—and to urgently address the more than 2.5 million “orphan wells” worldwide that lack responsible operators or proper documentation. The authors also recommend deploying satellite remote sensing, drone inspections, and AI-assisted detection, alongside the development of high-integrity plugging standards to ensure emissions are fully and permanently sealed.
The CEADs-AOGI database created in this study offers an open-access foundation for integrating AOG well emissions into national climate plans, voluntary corporate disclosures, and global methane accountability mechanisms.
“Abandoned oil and gas wells are out of sight—but they don’t have to be out of control,” says Dr. Lei. “With the right data and fast action, we can turn these overlooked sources into fast wins for the climate.”
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See the article:
A global inventory of methane emissions from abandoned oil and gas wells and possible mitigation pathways
Journal
National Science Review