Across New Mexico and the entire United States, hundreds of thousands of undocumented, orphaned oil-and-gas wells have the potential to pollute water and leak methane and other toxic gases into the atmosphere, contributing to rising global temperatures. The first challenge to plugging these wells is locating them.
A methane moment
Carbon dioxide gets the spotlight as a heat-trapping greenhouse gas that’s driving up average global temperatures, but methane is more than a bit player. While it doesn’t last as long in the atmosphere as carbon dioxide, in the short term, methane is 25 times more potent at trapping heat and accounts for a fifth of global warming. In 2021, the United States joined an international methane pledge to reduce methane emissions 30% by 2030, compared to 2020 levels.
A wide range of sources release methane into the atmosphere: agriculture, swamps, animals, coal and oil and gas operations, including orphaned wells. Methane emissions from abandoned oil-and-gas wells are the tenth-largest methane source. Methane-leaking wells also have the potential to leak other contaminants into groundwater, soil and air.
Orphaned wells’ owners have abandoned them, gone out of business, or disappeared. In any case, no one claims legal responsibility. Worse, many of the wells are not mapped or documented, so any information about their construction and location has been lost.
The Interstate Oil and Gas Compact Commission estimates between 310,000 and 800,000 undocumented orphaned wells, often more than 100 years old, dot the nation’s landscape. New Mexico has about 1,700, that we know of, while Pennsylvania has an astonishing 34,000. Abandoned before records were kept, they often hide under dense vegetation or—worse—under homes, driveways and schools.
Finding them typically means scanning the ground with magnetometers, which rely on the Earth’s weak magnetic field to spot steel in the ground. Unfortunately, the metal can evade detection like a needle in a haystack, and many well casings were ripped out of the ground in the quest for scrap steel during World War II — sometimes, there’s only a haystack, with no needle. So the wells have to be found using other methods.
Developing and refining new methods to find these wells is a big part of the mission of a new consortium funded with $40 million by the Department of Energy, Office of Fossil Energy and Carbon Management, under the Bipartisan Infrastructure Law. The DOE effort is designed to support the Department of Interior’s $4.7 billion investment to plug and remediate orphaned oil and gas wells. Los Alamos is providing technical guidance for the DOE effort. New Mexico received $25 million in DOI initial grants to find and fix its orphaned wells.
Led by Los Alamos National Laboratory, the Consortium Advancing Technology for Assessment of Lost Oil & Gas Wells includes representatives from four other national labs, stakeholders include the Interstate Oil and Gas Compact Commission and the DOI. Together we’re locating and characterizing undocumented orphaned wells and measuring their methane emissions, while developing best practices for well remediation.
This information will help federal and state agencies around the country prioritize which wells should be plugged and cleaned up. Not all wells are causing big environmental problems — many emit less methane than a single cow. From a cost-benefit perspective, less problematic wells should be identified and pushed down the priority list in a kind of triage so the worst offenders can be fixed first.
Tracking down the worst offenders
Our consortium is deploying a number of new technologies to track down these wells. Fixed-wing drones, for instance, can efficiently and cost-effectively carry magnetometers, methane detectors and lidar, over likely areas to detect the often-faint evidence of a well, whether it’s a whiff of methane or the blip caused by a steel well casing.
These different sensors often give different answers about potential leaky well locations since the signal is often weak and noisy, so we use state of the art machine learning to combine the varied, noisy data sets and extract a useful signal pinpointing a well’s location. We are also using large language models such as ChatGPT to scour the historical records to find these elusive wells.
Measuring methane leakage at a well is costly and cumbersome. Currently, when someone finds an orphaned well, they install equipment, at $10,000 to $30,000 per well, to measure the flow rate of leaking methane. By lowering costs, more wells can be plugged with the $4.7 billion. Currently, most plugging-and-abandonment companies cap wells without measuring methane emissions since methane mitigation had not been in their previous charge.
To address this multifaceted problem, DOE asked our consortium to develop a screening method to estimate the flow rate of a methane plume based on the much cheaper-to-measure metric of methane concentration at the wellhead. That’s hard to do reliably, but the consortium has drawn on our innovative research modeling methane plumes in other settings and our expertise in inverse modeling and uncertainty quantification to solve the problem.
Essentially, we run the plume model backward, incorporating wind speed and other factors. Then we apply a formula setting limits on the uncertainty of the model and come up with an estimated flow rate. If the rate is high enough to warrant mitigation, we’ll double-check by measuring methane flow at the source.
Using this new approach, we can accelerate locating and prioritizing the wells that need remediation and skipping those that don’t. With hundreds of thousands of orphan wells scattered across the country, we can save millions of dollars and crucial time in the race to rein-in methane pollution.
We’re currently working with other consortium researchers who are validating our models in the field on already-known wells. We hope our approach will become a best practice in mitigating the environmental damage done by orphaned wells and in slashing methane pollution in general, as part of our nation’s overall strategy to address climate change.
Hari Viswanathan is an environmental scientist at Los Alamos National Laboratory and the lead scientist on the CATALOG consortium. Funded under the Bipartisan Infrastructure Law, the consortium comprises Los Alamos, the Interstate Oil and Gas Compact Commission, the U.S. Department of Interior, Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, National Energy Technology Laboratory and Sandia National Laboratories.
