Plugged Wells Still Leaking Methane
“When a state sees a well is plugged, they typically put a checkmark by that well in a database, or in a file somewhere, and they don’t do anything [else],” said Rob Jackson, a scientist at Stanford University.
Unless a well starts leaking fluids or a house blows up, the assumption is that everything is fine. But recent work by Jackson’s research group challenges that idea.
Methane is the main component of natural gas, and it is present in every oil and gas well. It’s also a potent greenhouse gas that’s potentially explosive when it accumulates in confined spaces. In Pennsylvania and California, Jackson and his colleagues have tested abandoned wells, both plugged and unplugged, for methane leaks. The results are surprising; in most cases, the wells were leaking extremely small quantities of methane, but a few wells were leaking several orders of magnitude more. It wasn’t just the unplugged wells. Some of those ‘super emitters’ had been plugged.
The Canadian province of Alberta, the energy center of that country, requires companies to monitor some abandoned wells. They’ve found that on average, 7.7 percent of wells end up leaking.
But whether those results translate to Wyoming and Colorado is hard to say, since no one is looking for leaks. Stanford’s Rob Jackson thinks it’s partly an issue of states not having the resources to monitor.
Then again, even if authorities were interested, they’d probably have a hard time tracking down old wells. Once a well is plugged with cement, it is cut off below-ground, covered up with dirt and then, more often than not, never thought of again. Sometimes, a dead well is marked with a tombstone of sorts, a marker listing its unique identifying number, but often there’s no indication whatsoever on the surface.