Abandoned Well Study in Pennsylvania Not Airtight
The Guardian reported last week on a new study out of Princeton University that looked at the leakage of methane from abandoned wells in Pennsylvania. Now, aside from the somewhat comical title—“Thousands of Fracking Wells in Pennsylvania ‘may be leaking methane’”—the article does bring up an issue that is far from new for the Commonwealth.
Generally these days when someone refers to a well as a “fracking well” in Pennsylvania, they tend to be describing an unconventional Marcellus Shale well drilled in the last decade. That’s not the case with the Guardian article or the Princeton study that looks at legacy orphan wells dating back to the 1800s, which may or may not have been hydraulically fractured.
According to the Pennsylvania Department of Environmental Protection (DEP),
“Since the first commercial oil well was drilled in Pennsylvania in 1859, it is estimated that 300,000 oil and gas wells have been drilled in the state. Only since 1956 has Pennsylvania been permitting new drilling operations, and not until 1985 were oil and gas operators required to register old wells.”
What was the study’s focus?
Mary Kang, a doctoral candidate at Princeton, studied 19 wells in McKean and Potter Counties. Out of those wells, only one is listed in the DEP’s abandoned and orphaned wells database and only five were classified as plugged. Dr. Terry Engleder from Penn State University said in the Guardian article,
“(The) flaw in the Kang study is that she tells the reader nothing about the wells she is sampling,” such as the well depth and the formation into which the well was drilled to produce oil or gas.
Aside from depth or formation, she also doesn’t describe when the well was developed, although she does include a section in Chapter 5 detailing Pennsylvania’s history of legacy wells, many of which are from the 1880s when Pennsylvania’s Bradford Oil Field produced 83 percent of America’s oil (p 80).
Kang herself estimates the number of orphaned wells to be “from 300,000 to 500,000 but may be up to 970,000” (p. 6). So by Kang’s own estimates of potential abandoned wells in Pennsylvania, 19 wells would not be a significant sample size to then make the jump that all abandoned wells are leaking, as Engleder pointed out in the Guardian article.
“…while methane is clearly leaking from abandoned wells, it’s unlikely that all of the state’s abandoned and plugged wells are leaking.
Leakage may depend on the specific geologic formation a well taps because wells in some formations would release much gas early in the drilling process and much less, if any, later on, he said.”
Kang also estimates that the total leakage “translates to 4 to 13% of total estimated state-wide anthropogenic methane emissions in Pennsylvania” (p 100). She does not mention, however, that production from wells tends to diminish over time, even with active wells, so estimates of methane contribution may be exaggerated as well, depending on not only if a well is in fact leaking, but the age of the well. As Lawrence Cathles from Cornell University says in the Guardian article,
“I don’t think presently leaking wells will change our perspective on greenhouse warming because their leakage has already been accommodated by the climate system and methane is only 20 to 30 percent the total greenhouse forcing at present,” Cathles said via email. “What matters is how methane leakage changes in the future. If the well leakage is significant, reducing it in historic wells might reduce greenhouse forcing somewhat (and thus present a remedial opportunity).”
He said it might be beneficial to minimize future methane leakage from abandoned oil and gas wells if Kang’s research holds up to scientific scrutiny.
What is being done?
The DEP currently has a registry that includes 12,149 abandoned and orphaned wells located predominantly in the western part of the state where much of the historic oil and gas development occurred. Of those, 3,467 have been plugged.
Anyone who has found an abandoned legacy well on their property may call their local DEP office to report it and get the well added to the registry. The DEP then uses money from the Well Plugging Program to plug these wells free of cost to the landowner based on risk assessment, with higher priority wells being plugged first.
For local governments, universities or other organizations, part of Act 13 of 2012 also sets aside money for the Orphan or Abandoned Well Plugging Program (OAWP). OAWP provides funds of up to $250,000 to assist in the plugging of abandoned wells, as well as the installation of methane venting systems for the remediation process.
Kang’s study only looks at a fraction of the wells known to be abandoned—hopefully the 18 others she studied have been reported and registered—and is not nearly a large enough sampling to make the jump that all wells are leaking or even that the leakage rates are significant contributors to the states emissions levels. What it does help to do, though, is bring further awareness to an issue the state has faced since the 1800s and one that continues to be re-evaluated as better means of identification and remediation become available.