Abandoned wells can be 'super-emitters' of greenhouse gas (Update)

Abandoned wells can be 'super-emitters' of greenhouse gas
One of the wells the researchers tested; this one in the Allegheny National Forest. Credit: Princeton University

Princeton University researchers have uncovered a previously unknown, and possibly substantial, source of the greenhouse gas methane to the Earth's atmosphere.

After testing a sample of abandoned oil and natural gas wells in northwestern Pennsylvania, the researchers found that many of the old wells leaked substantial quantities of methane. Because there are so many abandoned wells nationwide (a recent study from Stanford University concluded there were roughly 3 million abandoned wells in the United States) the researchers believe the overall contribution of leaking wells could be significant.

The researchers said their findings identify a need to make measurements across a wide variety of regions in Pennsylvania but also in other states with a long history of oil and gas development such as California and Texas.

"The research indicates that this is a source of methane that should not be ignored," said Michael Celia, the Theodore Shelton Pitney Professor of Environmental Studies and professor of civil and environmental engineering at Princeton. "We need to determine how significant it is on a wider basis."

Methane is the unprocessed form of natural gas. Scientists say that after carbon dioxide, methane is the most important contributor to the greenhouse effect, in which gases in the atmosphere trap heat that would otherwise radiate from the Earth. Pound for pound, methane has about 20 times the heat-trapping effect as carbon dioxide. Methane is produced naturally, by processes including decomposition, and by human activity such as landfills and oil and gas production.

While oil and gas companies work to minimize the amount of methane emitted by their operations, almost no attention has been paid to wells that were drilled decades ago. These wells, some of which date back to the 19th century, are typically abandoned and not recorded on official records.

Mary Kang, then a doctoral candidate at Princeton, originally began looking into methane emissions from old wells after researching techniques to store carbon dioxide by injecting it deep underground. While examining ways that carbon dioxide could escape underground storage, Kang wondered about the effect of old wells on methane emissions.

"I was looking for data, but it didn't exist," said Kang, now a postdoctoral researcher at Stanford.

In a paper published Dec. 8 in the Proceedings of the National Academy of Sciences, the researchers describe how they chose 19 wells in the adjacent McKean and Potter counties in northwestern Pennsylvania. The wells chosen were all abandoned, and records about the origin of the wells and their conditions did not exist. Only one of the wells was on the state's list of abandoned wells. Some of the wells, which can look like a pipe emerging from the ground, are located in forests and others in people's yards. Kang said the lack of documentation made it hard to tell when the wells were originally drilled or whether any attempt had been made to plug them.

"What surprised me was that every well we measured had some methane coming out," said Celia.

To conduct the research, the team placed enclosures called flux chambers over the tops of the wells. They also placed flux chambers nearby to measure the background emissions from the terrain and make sure the methane was emitted from the wells and not the surrounding area.

Although all the wells registered some level of methane, about 15 percent emitted the gas at a markedly higher level—thousands of times greater than the lower-level wells. Denise Mauzerall, a Princeton professor and a member of the research team, said a critical task is to discover the characteristics of these super-emitting wells.

Mauzerall said the relatively low number of high-emitting wells could offer a workable solution: while trying to plug every abandoned well in the country might be too costly to be realistic, dealing with the smaller number of high emitters could be possible.

"The fact that most of the methane is coming out of a small number of wells should make it easier to address if we can identify the high-emitting wells," said Mauzerall, who has a joint appointment as a professor of civil and environmental engineering and as a professor of public and international affairs at the Woodrow Wilson School.

The researchers have used their results to extrapolate total methane emissions from abandoned wells in Pennsylvania, although they stress that the results are preliminary because of the relatively small sample. But based on that data, they estimate that emissions from abandoned wells represents as much as 10 percent of methane from human activities in Pennsylvania—about the same amount as caused by current oil and gas production. Also, unlike working wells, which have productive lifetimes of 10 to 15 years, abandoned wells can continue to leak methane for decades.

"This may be a significant source," Mauzerall said. "There is no single silver bullet but if it turns out that we can cap or capture the methane coming off these really big emitters, that would make a substantial difference."

Explore further

Early tests don't find tainted water from oil boom

More information: "Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania," by Mary Kang et al. PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1408315111
Provided by Princeton University
Citation: Abandoned wells can be 'super-emitters' of greenhouse gas (Update) (2014, December 8) retrieved 20 July 2019 from https://phys.org/news/2014-12-abandoned-oil-gas-wells-emit.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Dec 08, 2014
Not if properly plugged and abandoned.

Dec 08, 2014
Then, do it, Odin.

Dec 08, 2014
The oil industry saves money by cutting corners and cutting the lives of the people poisoned by them.

Dec 09, 2014
OdinsAcolyte is wrong and the study proves him wrong. Properly abandoned oil and gas wells WERE included in the study and even THEY leaked. I worked with the field guide team for this study and we made sure we included, as requested by Princeton, properly abandoned oil and gas wells.

And they were measured using the same process and the same equipment and they were also found to be leaking. Some of them, significantly.

tl/dnr is not a valid excuse, this is serious science and you should read the study and not make assumptions.

Dec 09, 2014
Excavators are used to build the 1 to 5 acre well pad. The picture shows a new well pad under construction. The photo is accurate, the legend used for the photo could be more accurate though.

Dec 09, 2014
The picture has now been changed to show, what is actually, a common abandoned well in PA.
Yes, abandoned wells that look like this, are all too common.

Dec 09, 2014
"Although all the wells registered some level of methane, about 15 percent emitted the gas at a markedly higher level"

In other news, Princeton researchers "completely blown away" to discover work of long dead Italian economist Vilfredo Pareto.

Dec 10, 2014
Actually...it's kind of the Pareto Principle in reverse....15% of these things are blowing their load because they're horribly poorly built and broken down.

Dec 13, 2014
And they were measured using the same process and the same equipment and they were also found to be leaking. Some of them, significantly.

Just curious, were any of them leaking enough to make it worthwhile to a homeowner with one on their property to collect it and compress it into a tank for use?

Dec 14, 2014
Makes plans for underground disposal of CO2 a bit shaky across a lot of the country; what happens if there's a blow-out from a full 'holding' ? One abandoned well pops ? Embarassing. Two ? Five ? A dozen ? Investigation. Dozens ? Hmm. I'm reminded of those volcanic African lakes where an 'overturn event' released a smothering cloud of CO2 onto folk down-hill from the crater...

Make a neat, low-budget shaky-cam disaster movie...

Jan 30, 2015
@24Volts - YES....Most of them were and yes, it was recommended at the end of the Princeton paper to do something to capture that energy.

Problem we have here, in PA, if you do anything to alter that well, or have benefited in any way from that well, you now own that well and are 100% responsible for that well. Now and into the future.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more