(Re)Exploration: CATALOG
There may be as many as 800,000 orphan wells across the United States: Until recently, well mapping was irregular and records were often lost as properties changed ownership. Many of these forgotten wells are over 100 years old, and have simply become part of the landscape – covered by vegetation, in pastures, under housing developments, and even near schools.
These wells can be silent sources of ground, air, or water contamination due to leaks and unchecked greenhouse gas emissions, particularly methane. Plugging these wells to stop methane emissions is key to protecting the environment – abandoned oil and gas wells are the 10th largest source of US methane emissions. The challenge is finding the wells. Standard detection methods rely on locating the steel well structures using magnetometers, but many well casings and parts were removed as scrap metal, leaving no way to find the well.
Modern technologies are being developed and deployed to locate these orphaned wells. The CATALOG Wells (Consortium Advancing Technology for Assessment of Lost Oil & Gas Wells) is a project led by the Los Alamos National Laboratory and in collaboration with DOE, DOI, and the Interstate Oil and Gas Compact Commission. It is made up of researchers and scientists from Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, National Energy Technology Laboratory and Sandia National Laboratories, supported by Bipartisan Infrastructure Law funding. This consortium has brought together technical expertise, digital tools, and existing records to locate orphan wells and to measure their methane emissions, while also developing well remediation best practices.
Locating Wells
Fixed-wing drones carrying magnetometers, methane detectors, and lidar are used to detect methane or steel well casing remnants, and machine learning helps refine and sort signals to pinpoint probable old well sites. Cross referencing the data collected with large language models (like ChatGPT) containing historical land ownership records also provides location precision.
Measuring Methane
Methane emissions are estimated based on methane concentration at the wellhead. New screening techniques use methane plume analysis and mathematical modeling to estimate methane flow at a well site, rather than traveling to the site to install measurement equipment (which can cost $10,000 to $30,000 per site). Sites determined to be high methane emitters can then be scouted to confirm emissions and prioritized for remediation.
Plugging Economics
The consortium goal is to collect data to allow prioritization of orphan well plugging, based on realistic and real-time cost-benefit analysis of well characteristics. Plugging costs per well vary widely, and are location, type, and depth-dependent – costs range from $20,000 to $1 million dollars. Federal and state funding can then be allocated to mitigate the most problematic orphan wells first – maximizing the funding and minimizing methane impact on the environment by plugging these derelict orphaned wells.
