The number of orphaned and abandoned wells varies greatly depending on their definition. According to the U.S. Environmental Protection Agency, there might be millions of old and improperly plugged oil and gas wells leaking methane or contaminating groundwater in the United States, and plugging them will cost billions.
The first U.S. oil well was drilled 1859 in Titusville, Penn., and the first commercial gas well was even earlier in 1825 in Fredonia, N.Y. There are two centuries of oil and gas drilling in the United States, and many of the wells in the first 150 years did not have the best plug-and-abandonment methods in place.
Some of these wells are in urban areas and can endanger the residents. In Los Angeles alone there might be a thousand orphaned wells. For Placerita Oil Field in Los Angeles County, the state of California will spend $3.3 million to plug 56 abandoned wells because of their proximity to residences and potential groundwater contamination.
The number of orphaned and abandoned wells varies greatly depending on their definition. According to the U.S. Environmental Protection Agency, there might be millions of old and improperly plugged oil and gas wells leaking methane or contaminating groundwater in the United States, and plugging them will cost billions. In 2020, the Interstate Oil and Gas Compact Commission estimated there were at that time 310,000-800,000 undocumented unplugged orphaned wells in 21 states.
These wells can also have a detrimental effect on climate and a negative public perception on the oil and gas industry. Some wells will continue to emit methane decades after being abandoned, and methane has 80 times the warming capacity of CO2 in the first 20 years after atmospheric release. A paper by Mary Kang in 2014 estimated that 4-7 percent of total anthropogenic methane emission in Pennsylvania come from abandoned wells.
With the advent of the carbon capture, utilization and storage industry, the identification of orphaned wells becomes of critical importance for safe storage of CO2. These wells could be potential leakage pathways for migration of CO2 to the groundwater or surface. U.S. Department of Energy projects include identifying all legacy wells in their funded projects to avoid these scenarios.
This year the Division of Environmental Geology of AAPG has sponsored two webinars on orphaned wells.
The continuing importance of orphan wells has led the AAPG to propose a two-day conference on orphaned, abandoned and idle wells on Feb. 21-22, 2023, in Oklahoma City. The conference will discuss how to find them, how to plug them, how geology can complicate their plugging, beneficial alternative uses of orphaned wells, newly available funding sources, historical practices as they relate to borehole integrity, emissions control, groundwater protection and future, emerging opportunities such as carbon credits and blockchain.