Methane emissions from abandoned oil and gas wells underestimated

January 19, 2021

A recent McGill study published in Environmental Science and Technology finds that annual methane emissions from abandoned oil and gas (AOG) wells in Canada and the US have been greatly underestimated - by as much as 150% in Canada, and by 20% in the US. Indeed, the research suggests that methane gas emissions from AOG wells are currently the 10th and 11th largest sources of anthropogenic methane emission in the US and Canada, respectively. Since methane gas is a more important contributor to global warming than carbon dioxide, especially over the short term, the researchers believe that it is essential to gain a clearer understanding of methane emissions from AOG wells to understand their broader environmental impacts and move towards mitigating the problem.

Multiple sources of uncertainty

The researchers show that the difficulties in estimating overall methane emissions from AOG wells in both countries are due to a lack of information about both the quantities of methane gas being emitted annually from AOG wells (depending on whether and how well they have been capped), and about the number of AOG wells themselves.

"Oil and gas development started in the late 1850s both in Canada and the US," explains Mary Kang, the senior author on the paper and an assistant professor in the Department of Civil Engineering at McGill. "Many companies that dug wells have come and gone since then, so it can be hard to find records of the wells that once existed."

Thousands of undocumented AOG wells

To determine the number of AOG wells, the researchers analyzed information from 47 state, provincial or territorial databases as well as from research articles and national repositories of drilled and active wells in the US and Canada.

They found that, of the over 4,000,000 AOG wells they estimate to exist in the US, more than 500,000 are undocumented by the relevant state agencies. A similar picture emerges in Canada. The Canadian Association of Petroleum Producers (CAPP) only has records going back to 1955 although historical documents confirm that oil and gas activity in Canada began in the 1850s. Based on the various sources they examined, the researchers estimate that there are over 370,000 AOG wells in Canada. Over 60,000 of are not included in databases of provincial or territorial agencies.

More methane gas emitted by AOG wells than shown by government records

To gain a better sense of exactly how much methane was being emitted from the wells, the researchers analyzed close to 600 direct measurements of methane emissions drawn from existing studies covering the AOG wells in the states of Ohio, Wyoming, Utah, Colorado, Oklahoma, West Virginia and Pennsylvania in the US and from British Columbia and New Brunswick in Canada. They developed different scenarios to attribute different levels of annual methane emissions to the wells, depending on what is known of the plugging status of the wells as well as whether they were oil or gas wells.

"We see that methane emissions from abandoned wells can vary regionally, highlighting the importance of gathering measurements from Texas and Alberta which have the highest percentage of wells in the U.S. and Canada and no prior measurements," adds James P. Williams, the first author on the study and a Ph.D. student in the Department of Civil Engineering at McGill.

All five scenarios show annual emissions of methane gas from AOG wells in the US that are approximately 1/5th higher than the amount that the US EPA's estimates for 2018. In Canada, the study findings suggest that methane emissions from AOG wells in 2018 were nearly three times higher than estimated by Environment and Climate Change Canada.

"As society transitions away from fossil fuels, the millions of oil and gas wells around the world will be abandoned," says Kang. "It is critical to determine the climate, air, water and other environmental impacts of these wells quickly."
To read: "Methane Emissions from abandoned oil and gas wells in Canada and the US" by James P. Williams, Amara Regehr and Mary Kang in Environmental Science and Technology
DOI: 10.1021/acs.est.0c04265

The research was funded by Fonds de Recherche du Quebec Nature et Technologie, the McGill Engineering Doctoral Award and the McGill Graduate Mobility Award.

About McGill University

Founded in Montreal, Quebec, in 1821, McGill University is Canada's top ranked medical doctoral university. McGill is consistently ranked as one of the top universities, both nationally and internationally. It is a world-renowned institution of higher learning with research activities spanning two campuses, 11 faculties, 13 professional schools, 300 programs of study and over 40,000 students, including more than 10,200 graduate students. McGill attracts students from over 150 countries around the world, its 12,800 international students making up 31% of the student body. Over half of McGill students claim a first language other than English, including approximately 19% of our students who say French is their mother tongue.


Katherine Gombay
McGill Media Relations Office

McGill University

Related Methane Articles from Brightsurf:

When methane-eating microbes eat ammonia instead
As a side effect of their metabolism, microorganisms living on methane can also convert ammonia.

Making more of methane
Looking closely at the chemical process that transforms methane into useful products could help unveil more efficient ways to use natural gas.

Methane: emissions increase and it's not a good news
It is the second greenhouse gas with even a global warming potential larger than CO2.

Measuring methane from space
A group of researchers from Alaska and Germany is reporting for the first time on remote sensing methods that can observe thousands of lakes and thus allow more precise estimates of methane emissions.

New 3D view of methane tracks sources
NASA's new 3-dimensional portrait of methane concentrations shows the world's second largest contributor to greenhouse warming.

Show me the methane
Though not as prevalent in the atmosphere as carbon dioxide, methane is a far more potent greenhouse gas.

Containing methane and its contribution to global warming
Methane is a gas that deserves more attention in the climate debate as it contributes to almost half of human-made global warming in the short-term.

Microorganisms reduce methane release from the ocean
Bacteria in the Pacific Ocean remove large amounts of the greenhouse gas methane.

Origin of massive methane reservoir identified
New research provides evidence of the formation and abundance of abiotic methane -- methane formed by chemical reactions that don't involve organic matter -- on Earth and shows how the gases could have a similar origin on other planets and moons, even those no longer home to liquid water.

Unexpected culprit -- wetlands as source of methane
Knowing how emissions are created can help reduce them.

Read More: Methane News and Methane Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to