HARRISBURG — Pennsylvania has an estimated 200,000 abandoned oil and gas wells, but knows the location of only a tiny fraction of them — a potential problem for Marcellus Shale drillers trying to avoid the old wells, according to a published report.
Though it's rare for a modern drilling operation to intersect with an abandoned well, it does happen. A subsidiary of Shell Oil Co. was drilling in Tioga County last summer when a 30-foot geyser of methane gas and water erupted from the ground, prompting the evacuation of several homes until the leak was brought under control.
The gas most likely came from a shallow formation and made its way into an abandoned well drilled in 1932, according to StateImpact Pennsylvania, a collaboration of public radio stations WITF in Harrisburg and WHYY in Philadelphia.
Gene Pine, who runs a division of the state Department of Environmental Protection that is charged with finding and plugging abandoned wells, estimated that about 325,000 wells have been drilled in Pennsylvania since Edwin Drake sank the first commercial oil well in Titusville in 1959. Of those, only 120,000 have state permits on file.
"There's probably close to 200,000 wells that are largely or relatively unaccounted for in the commonwealth," Pine said. Of those, the state knows the location of only 8,257. Until 1955, the state did not require operators to report the locations of their wells.
Pine's division has plugged 2,871 wells since the 1980s, but a lack of funding has long slowed the pace. Instead, DEP focuses on wells that pose the greatest threat. Many other states with large numbers of abandoned wells also spend little money to plug them.
"We can't plug every well. We don't have the resources to do that, nor do we have the contractors to do that," Pine told StateImpact. "If there's no evidence a well is leaking oil or gas, and it's not near a home or body of water, then that would be given a lower priority than a well that clearly is leaking into a stream, or is near a backyard."
The drillers themselves have incentive to identify and plug abandoned wells because they are legally and financially responsible for any damage that results when their drilling sites intersect with old wells.