Orphaned wells remain a problem

Nathan Meehan, PhD, P.E., Professor, Harold Vance Department of Petroleum Engineering, Texas A&M University

Orphaned and idled wells remain stubbornly on the to-do list for U.S. oil and gas regulators, even with new money and momentum behind cleanup efforts. An orphaned well is a well that no longer has a financially responsible operator. This is usually because the company went bankrupt or walked away, and the state or federal government has determined there’s no viable party left to pay.  

An idled (often called inactive) well is different: it’s shut-in and not producing, but it still has a responsible operator on the hook. Idled wells are a practical concern because, left unmanaged, they’re the main feeder pipeline into the orphaned category. A few states publish the additions to the orphaned well counts monthly, and it is clear their numbers are increasing.  

While we used to use the term “plug and abandon,” and “abandoned wells” to refer to wells that had been appropriately abandoned, these are just part of decommissioning, Fig. 1. In addition to installing permanent downhole barriers to isolate formations, cutting and capping the well at or below grade, we remove equipment and flowlines, clean up any spills, and restore the site to something close to its predrill condition. Spilled oil may degrade over time, but spilled salt water often requires removal and replacement of soil. Decommissioning is the only proven, durable way to stop leaks and eliminate ongoing risk from these wells. Often the term “abandoned well” is used to refer to a well with no responsible operator. 

Fig. 1. Abandoned wells are really just part of decommissioning. Image: USGS.

The scale is large and still shifting.  There are more than 117,000 orphaned wells, with location accuracy for most of them, but the count continues to grow as agencies inventory old fields and digitize records. The Interstate Oil and Gas Compact Commission estimates there are many more undocumented orphaned wells (in the range of 310,000 to more than 800,000) that were drilled and never recorded or were plugged with now-inadequate methods. That long tail exists, because the U.S. drilled wells for more than a century before modern rules were in place, bonds were often too small to cover true decommissioning costs, and enforcement ebbed and flowed with commodity cycles.  

Orphaned wells can emit methane, hydrogen sulfide, and volatile organic compounds, and they can act as conduits for brine, hydrocarbons, and other fluids to move vertically, if barriers have degraded. Methane is a particularly efficient climate forcer in the near term, and emissions are highly skewed: a minority of wells account for most of the leak load, which is why locating and fixing the high emitters pays off.  

Many early wells were never cemented to modern standards; most modern wells should not leak but there are exceptions. The public-facing side of this is proximity. National datasets show millions of people live within a mile of a documented orphaned well, including disproportionate numbers of minority residents, older adults, and people with disabilities.¹ Thousands of schools and hundreds of hospitals fall within plausible exposure buffers, and there are documented overlaps with domestic water wells, surface waters, parks, and critical habitats. Beyond environmental risk, unplugged wells can dent nearby property values and complicate underground energy storage and future CO₂ sequestration by providing leakage pathways. 

It is uncertain how many previously plugged wells have failed. Relatively few that have been plugged begin leaking in significant quantities to the surface, but many more may not contain reservoir fluids and brines downhole. If these leaks do not pose risks to human health, they are irrelevant, but some will impact subsequent development activities including subsurface storage.  

With that context, what are states doing? Most oil and gas agencies now run riskbased priority lists to decide which wells to decommission first. The better programs publish scoring criteria and keep them updated, so the public and landowners can understand the queue. Typical factors include signs of gas seepage; proximity to homes, schools, or water wells; risks to drinking water aquifers; surface impacts, such as brine-kill areas; and site access.  

Increasingly, agencies fold in environmental justice screens and methane measurements. Because mobilization and rig time are expensive, many states bundle wells by geography, so crews can move efficiently, mixing a few lower-priority wells into high-priority projects when they’re in the same vicinity. 

There’s also a quiet but important buildout of the basics: finding wells in the first place. Crews pull old lease maps and drilling reports, talk to landowners, run magnetometers and drones to spot casings or cellar hardware, and use methane or soil-gas sniffers to locate unknown leaks.  

The mechanics of decommissioning are improving, but practices still vary widely. Some states require tagging or testing of cement plugs to confirm placement; others recommend it but don’t mandate it. Witnessing the key aspects of P&A activities is also implemented in a variety of ways, and most states have a shortage of qualified individuals to perform such inspections. A recent survey suggests only a minority of states requires agencies to witness critical steps during plugging. Post-plug verification—pressure tests, tagging of plugs, logging to confirm cement—is not universal. The lack of standardized data on post-plug failures makes it hard to know how often plugs degrade and why. Few states have follow-on measurements or inspections after plugging operations are completed. 

Role of federal funding. Against this backdrop, the big change over the last few years is federal funding. The Bipartisan Infrastructure Law (BIL) set aside $4.7 billion for orphaned wells through DOI. The program has a few grant buckets—initial grants to jumpstart work, formula grants based on need, and performance grants tied to outcomes—and a parallel track for Tribes. States used the early money to inventory wells, hire staff, stand up contracting, and get rigs and cement on location. Since 2022, states report decommissioning thousands of orphaned wells with DOI funds, with many more under contract. Tribes have begun similar programs on their lands, some of which face particularly tough logistics and legacy well records. 

The new money is a major addition to state- and Tribal-funded activities and is: paying for field work, clearing backlogs of identified P&A candidates, and building a workforce. It’s also helping agencies pilot methane monitoring and surface remediation approaches and incorporate EJoriented prioritization. No one thinks $4.7 billion closes the gap. Costs per well range from tens of thousands of dollars for straightforward wells to several hundred thousand dollars or more when there are collapsed casings, lost tools, hydrogen sulfide, or sensitive surface conditions. Add in site restoration and, where needed, soil and groundwater cleanup, and the tab climbs. As inventories improve, counts go up. Taken together, the national bill to decommission documented and yet-to-be-found orphans likely runs to the tens of billions. 

So where does that leave idled wells? State efforts vary.  Some have raised blanket bond amounts and required wellspecific financial assurance, once a well sits idle past a defined period. Others require updated (increased) bonds when a property is sold. Others have set timelines and mechanical integrity checks that force a decision: return to service, temporarily abandon to a modern standard, or decommission. Transfers of older, low-producing wells to thinly capitalized operators are getting more scrutiny in several jurisdictions. These steps matter, because the cheapest orphaned well to decommission is the one that never enters the orphan pool. 

There’s occasional talk of repurposing old wells. There may be niche cases where a former oil well can serve as a geothermal test well, a monitoring well for CO₂ storage, or a site for smallscale surface renewables. Those uses may theoretically exist, but orphaned and idled wells rarely have the diameter, completion type, casing, and cement integrity suitable for reuse. Integrity is uncertain, liabilities are open-ended, and economics rarely exceed purpose-built infrastructure. Monitoring wells for ongoing activities is possible, but reuse isn’t a substitute for decommissioning at scale. The best thing to do with orphaned wells is almost always to plug them. 

What works? Decommission wells to current standards, verify the barriers, and remediate the surface. Manage idled wells, so they don’t become tomorrow’s orphans, and make sure bonds and transfer rules match real costs. While federal funds remain available, use that capacity to gather better data on emissions before and after decommissioning, on plug performance, and on failure modes, so the learning curve continues to steepen. 

The country has finally put real money and attention on a problem that built up over 160 years. It won’t be solved in a single funding cycle, and it won’t be solved by cleverness alone. It will be solved by steady, risk-based decommissioning, better idle-well discipline, and a long-term commitment to finishing the job. 

REFERENCE 

1. Meehan, D. N., Liu, M., Kang, M., & Peltz, A. S. (2025, October 20–22). Environmental issues with orphaned wells (Paper No. SPE-227933-MS). SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers. https://doi.org/10.2118/227933-MS

NATHAN MEEHAN is a Professor in the Harold Vance Department of Petroleum Engineering at Texas A&M University, conducting research in carbon capture, utilization, and storage (CCUS); blue hydrogen; quantifying and decreasing emissions from oil and gas operations, and monitoring and reporting; verification of GHG emissions; and enhanced recovery in unconventional wells using CO₂. He is a Senior Technology Advisor for oilfield data analytics firm Petro.ai, and a non-executive Director of Ignis H2, a geothermal energy startup. He was formerly President of CMG Petroleum Consulting, an energy advisory firm founded in 2001, President of Gaffney, Cline & Associates, and a senior executive at Baker Hughes. He served as the 2016 President of SPE. Previously he was Vice President of Engineering for Occidental Oil & Gas and General Manager, Exploration & Production Services, for Union Pacific Resources. He is a member of the National Academy of Engineering.  

Dr. Meehan holds a BSc degree in physics from the Georgia Institute of Technology, an MSc degree in petroleum engineering from the University of Oklahoma, and a Ph.D. in petroleum engineering from Stanford University. With more than 45 years of industry experience, he served as Chairman of the Board of the CMG Reservoir Simulation Foundation, as well as a director at several companies/organizations.   

Dr. Meehan’s awards and recognition include SPE Distinguished Member; SPE’s Lester C. Uren Award for Distinguished Achievement in Petroleum Engineering; the Degolyer Distinguished Service Medal; the SPE Public Service Award; SPE Honorary Member (the society’s highest award); the World Oil Lifetime Achievement Award; and Petroleum Economist’s Legacy Award. He was named 2023 Distinguished Alumni of the University of Oklahoma College of Earth and Energy.  

He serves, or has served on various academic advisory boards at University of Oklahoma, the Georgia Institute of Technology,  The University of Texas-Austin, University of Houston, Penn State, and St. Frances University. He has served on the National Petroleum Council and the Interstate Oil & Gas Compact Commission. Dr. Meehan is a widely published author and a licensed professional engineer in four states.