When a well is no longer in use, it must be properly closed and sealed to prevent impacts to water and air quality. Done correctly, wells are sealed with cement and multiple metal barriers to prevent fluid or gas from escaping and to keep people or animals from falling into the well. Once a well has been closed according to safety standards, it is considered abandoned and continues to be monitored to ensure it remains sealed.
According to the U.S. Environmental Protection Agency, as of 2016 there were an estimated 3.2 million inactive oil and gas wells in the United States, of these 69 percent – more than 2 million – are considered unplugged or remain improperly closed .
Wells that are not properly closed and sealed are referred to as “orphan” wells. Operators may leave wells unsealed, fail to create an impenetrable cement seal when closing a well, or the cement and casing may erode over time. Older wells once considered closed may still present a risk as historical practices do not meet today’s industry standards. Orphaned or improperly closed wells can emit large volumes of oil, other fluids or natural gas, including methane, that pose a risk to the environment and the health of neighboring communities and contribute to climate change.
Recent volatility in the oil and gas industry and bankruptcies have brought increased attention to the issue of orphaned wells. When wells are orphaned by their operators, state regulatory agencies assume responsibility for the cost of locating these wells and properly plugging and monitoring them. Sharing best practices and scientific evidence regarding orphaned wells can help states more efficiently manage this process to prevent costly, dangerous incidents.