Accurately measuring methane emissions from the oil and gas sector is vital to mitigating climate change. However, most existing estimates are inaccurate or incomplete. A new study by researchers at Stanford University, Kairos Aerospace, NASA’s Jet Propulsion Laboratory, and Carbon Mapper is helping close the gap between estimated and actual emissions in key oil and gas producing regions — intelligence that is critical to stopping them.
Researchers looked at data from nearly 1M airborne observations across major U.S. oil and gas basins, completed using the AVIRIS-NG instrument.
The study provides a first-of-its-kind estimate of large-scale comprehensive emissions across major U.S. oil and gas basins that together encompass 52% of all oil production and 29% of all gas production. The team combined the results of approximately one million aerial observations with an empirically grounded statistical model (more commonly known as a bottom-up emissions model) of smaller emissions sources.
Specifically, researchers looked at data from 959,573 airborne observations — most of which are available on our data portal — covering well sites and pieces of midstream infrastructure including compressor stations, gas processing plants, and pipelines from the Permian (TX and NM), San Joaquin (CA), Denver-Julesburg (CO), Uinta (UT), and Fort Worth (TX) basins, plus the Appalachian region (PA).
“This work is exciting because of the sheer magnitude of data analyzed as compared to existing ground-based measurement literature,” said Dr. Daniel Cusworth, Carbon Mapper Project Scientist and co-author on the study. “This large scale allows us to accurately characterize the contributions of low-probability, high consequence emissions that are missing with other measurement systems and existing inventories.”
Key study findings
Surveyed basins emitted high and undercounted volumes of methane: The surveyed regions in this study contribute an estimated 6.3 million tons per year of methane emissions, equivalent to total greenhouse gas emissions from France. The weighted average of emissions from these six regions is roughly three-times the national government inventory estimate. The social cost of methane emissions from these measured regions is roughly $9.4 billion per year, in addition to roughly $1 billion in lost sales.
Methane loss rates vary widely across surveyed basins: Methane emissions vary widely across regions and over time. The New Mexico portion of the Permian Basin was by far the highest emitter, with nearly 10% of total methane volume produced in 2019 going straight to the atmosphere. Surveys of some other regions, however, revealed emission rates well below U.S. EPA Greenhouse Gas Inventory estimates based on national averages, suggesting that good practices can reduce emissions.
A select number of facilities have an outsized impact on total regional emissions: Across all campaigns aerially detectable emissions occur at a small fraction of sites, 1.66% or less, but make an outsized contribution to total regional emissions. This proportion is beyond what would be expected if total estimates were based solely on a bottom-up emissions simulation method. High methane emissions point sources have an outsized impact on the total emissions in nearly all surveyed basins, a trend that Carbon Mapper has seen substantiated in past studies.
Midstream infrastructure is a common culprit for leaks: Midstream emissions stemming from compressor stations, gas processing plants, and pipelines accounted for a significant fraction of the emissions total across all basins.
Filling a critical gap
The AVIRIS-NG instrument was flown during a field campaign.
Reconciling basin-level emission estimates derived from ground-based or aircraft systems has historically been a challenge. These systems may miss some emission sources due to instrument or geographic sampling limitations, and quantifying the missing amount is challenging. Ground-based surveys can reliably see most small emissions sources, but they may miss strong sources like leaks from tanks and unlit or malfunctioning flares. Plus, they are expensive and only used to sample a limited number of sites meaning they potentially miss large, more variable emissions. In contrast, airborne surveys, though not sensitive to the smallest emissions sources, can measure strong site-level emissions across large geographic areas efficiently, which is critical to understanding basin-level emission distributions. These two methods are complementary, but we’ve lacked a reliable way to combine data from these two detection methods to create more complete emissions inventories and assess intensity on a basin level.
By merging comprehensive aerial surveys and ground-based emissions in a unique way through- a measurement-based inventory, the team was able to generate insights on the quantity and location of oil and gas emissions that reveal consequential trends on both national and basin-scales.
These methods and insights provide powerful tools for a variety of key stakeholders. The study provides environmental regulators, companies, and agencies a firm scientific foundation upon which to assess how they can best use the expanding set of methane-sensing technologies across different regions and use cases. Operators and regulators can use these and a growing number of observations in their regions to target intervention approaches that yield significant methane reductions (like focusing on sites that contribute a large portion of overall emissions, and/or modifying equipment or operations at high priority facilities). National and international leaders can also see the value in incorporating comprehensive measurement campaigns to build more accurate emissions inventories to track progress and build strategies to survey emissions at regular intervals.
Looking ahead
This study is just the tip of the iceberg, and additional comprehensive measurement campaigns are needed to reveal the full extent of undercounting that may be occurring in official inventory estimates across the U.S. and internationally. This work also points out the need for better data fidelity underlying emission simulation methods.
With a growing ecosystem of methane detecting satellites helping to scale visibility into methane emissions, Carbon Mapper is proud to help play a key role in expanding the technologies, data, and insights available to make emissions more transparent and actionable. Carbon Mapper’s data portal already includes nearly 13,000 high emission methane point sources detected globally, and soon, the first two satellites being developed by the Carbon Mapper Coalition will scale up the data available on strong methane point sources globally.
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