Aging Oil Wells Shift Cleanup Risk to Smaller Operators

As oil and gas wells become less productive, they are often sold on to new operators. That is a normal part of asset management in a mature energy market. But new research suggests these transfers may also be moving environmental and financial risk down the chain.

A working paper co-authored by Catherine Hausman of the University of Michigan’s Ford School of Public Policy examined oil and gas well transfers in California, Texas, Colorado and Pennsylvania between 1992 and 2023. Using regulatory data, the researchers tracked hundreds of thousands of transactions and found that well ownership changes are both frequent and repeatable.

Across the four states studied, around 20,000 to 30,000 well transfers take place each year. A typical well changes operators roughly every 13 years.

The pattern is clearest among older, lower-producing wells. As output falls, wells become more likely to be sold, often moving from larger, higher-value companies to smaller firms with fewer financial resources.

There can be commercial reasons for this. Smaller operators may be able to run marginal wells at lower cost. However, the study also points to a wider concern for regulators, investors and communities: transfers may allow larger companies to reduce exposure to future cleanup and compliance costs.

Plugging costs are becoming a bigger liability issue

At the end of a well’s productive life, operators are expected to plug it safely. This process helps seal pathways that could allow methane, oil, gas or other contaminants to escape.

When wells are not plugged, the risks can include groundwater contamination, air pollution, methane emissions and, in some cases, explosion hazards. These risks can become harder to manage when wells sit with operators that lack the balance sheet strength to cover long-term obligations.

The study found that recently transferred wells were 5 percentage points less likely to be plugged than wells that had not changed hands. That finding suggests a gap between formal responsibility and practical financial capacity.

Cost is central to the issue. Plugging a typical well can cost between $22,000 and $180,000, depending on the site and well characteristics. States often require operators to provide financial assurances, such as bonds, to help cover those costs. But the research suggests current bonding requirements may often be too low to create a strong incentive for timely plugging.

For regulators, this creates a difficult oversight challenge. If financially stronger companies can transfer aging wells to weaker operators, states could face a rising number of orphaned or abandoned wells. In that scenario, cleanup costs may eventually fall to taxpayers.

Hausman and her co-authors argue that reforms should apply broadly across ownership structures, rather than focusing only on individual companies or specific transactions. The core issue is making sure plugging obligations remain enforceable and financially realistic, regardless of who owns the well at the end of its life.

For oil and gas companies, the findings add weight to conversations around asset retirement planning, environmental risk disclosure and transaction due diligence. The sale of marginal wells is a governance, reputational and long-term liability issue, and should be so treated.