When Princeton University researchers sampled old oil and natural has wells in northwestern Pennsylvania, they found all of them leaked methane, some in substantial quantities. A previous Stanford University study estimated there were roughly three million abandoned wells in the US alone, including in California and Texas.
Oil and gas companies attempt to keep methane emissions at working wells to a minimum, but up until now very little attention has been paid to wells drilled decades ago. Some of the Pennsylvania wells date back to the 19th century and are not recorded on official records.
In a paper published in the Proceedings of the National Academy of Sciences the researchers describe how they tested 19 abandoned wells in northwestern Pennsylvania. Records about the origins and condition of the wells did not exist and only one was on the state’s list of abandoned wells. Some of the wells were in forests or in people’s yards, and some had been reduced to a pipe in the ground.
All the wells emitted methane, but about 15% emitted the gas at a markedly higher level than the others. Researchers say finding and capping all the wells might be unworkable, but identifying the super-emitting wells and capping them would reduce the problem significantly. via