At least 4.5 million oil and gas wells have been drilled in the United States since the 1850s. About 3.5 million of those wells are now abandoned according to the Environmental Protection Agency.1 Some wells were plugged before abandonment, meaning they were properly shut down through the application of filling and sealing materials. Some abandoned wells are unplugged. The difference is important because an unplugged well can:2
- Emit methane, a potent greenhouse gas, and other harmful gasses into the atmosphere at higher rates than an unplugged well.
- Leach contaminants, gas, and oil into surrounding soils and waters.
- Create safety hazards that prevent lands from being used for recreation or other productive purposes.
Orphaned wells are a subset of abandoned wells. They are unplugged, nonproducing, and have no responsible operator.4 Because they lack a financially responsible party, the financial burden associated with plugging orphan wells falls on the government, and thus, the tax-paying public.3 Orphaned wells are, in effect, wards of the state. Due to poor record keeping during much of the 150-year history of oil and gas development in the United States, the locations of most unplugged orphaned wells are unknown 4.
A recent analysis identified 123,318 documented orphaned wells in the United States as of April 2022.3 States with the highest number of documented orphaned wells are Ohio (17%), Pennsylvania (15%), Oklahoma (13%), and Kentucky (12%), which collectively account for 56% of the total number of documented orphaned wells in the U.S.
States have reported an increase in the number of documented orphan wells since 2021. Presumably, this was caused by the $4.7 billion through the Infrastructure Investment and Jobs Act (IIJA), also known as the Bipartisan Infrastructure Law (BIL), to plug documented orphaned oil and gas wells and remediate and restore well sites across the country.3
Abandoned oil and gas wells are one of the most uncertain sources of methane emissions into the atmosphere.5 Current understanding suggests that documented orphaned oil and gas wells represent 5–6% of the methane released by all abandoned oil and gas wells. Emissions from undocumented orphaned wells could raise that to as high as 36% of the total methane emissions from abandoned wells.3
Plugging orphaned wells creates benefits beyond emissions reductions. Plugged wells often overlie potentially valuable underground storage formations for carbon dioxide, natural gas, and hydrogen. The land occupied by plugged wells can be repurposed for wind and solar energy facilities. Well plugging creates jobs via surface clean-up, remediation, and site restoration.6
The considerable potential climate, health, and ecological legacy of the vast number of orphaned wells demands that they be documented and remediated in a sound manner. Doing so reduces health and environmental risks while simultaneously offering potential productive uses of the land.
1 1990-2020 Draft Inventory of Greenhouse Gas Sources and Sinks; US EPA (2022)).
2 U.S Department of the Interior, “Assessing Methane Emissions from Orphaned Wells to meet Reporting Requirements of the 2021 Infrastructure Investment and Jobs Act (BIL): Federal Program Guidelines,” April 11, 2022,https://www.doi.gov/sites/doi.gov/files/federal-orphaned-wells-methane-measurement-guidelines-final-for-posting-v2.pdf
3 Boutot, Jade, Adam S. Peltz, Renee McVay, and Mary Kang. “Documented Orphaned Oil and Gas Wells Across the United States.” Environmental Science & Technology 56, no. 20 (October 18, 2022): 14228–36. https://doi.org/10.1021/acs.est.2c03268.
4 Merrill, Matthew D., Claire A. Grove, Nicholas J. Gianoutsos, and Philip A. Freeman. “Analysis of the United States Documented Unplugged Orphaned Oil and Gas Well Dataset.” USGS Numbered Series. Analysis of the United States Documented Unplugged Orphaned Oil and Gas Well Dataset. Vol. 1167. Data Report. Reston, VA: U.S. Geological Survey, 2023.https://doi.org/10.3133/dr1167.
5 Williams, James P., Amara Regehr, and Mary Kang. “Correction to “Methane Emissions from Abandoned Oil and Gas Wells in Canada and the United States.” Environmental Science & Technology 55, no. 5 (March 2, 2021): 3449–3449. https://doi.org/10.1021/acs.est.1c00377.
6 Kang, Mary, Jade Boutot, Renee C. McVay, Katherine A. Roberts, Scott Jasechko, Debra Perrone, Tao Wen, et al. “Environmental Risks and Opportunities of Orphaned Oil and Gas Wells in the United States.” Environmental Research Letters 18, no. 7 (June 2023): 074012.https://doi.org/10.1088/1748-9326/acdae7.