Old, inactive oil and gas wells emitting almost 7 times more methane than official estimates

Inactive and abandoned oil and gas wells in Canada are a much bigger climate problem than previously thought, emitting almost seven times more methane than the official estimates, according to a new study from researchers at McGill University.

The potent greenhouse gas is responsible for a third of all global warming and traps 80 times more heat in the atmosphere than carbon dioxide. But Canada's efforts to curb methane emissions have focused on active oil and gas sites, rather than those that stopped operating decades ago.

The McGill study says methane emissions from these wells is about 230 kilotonnes yearly, as opposed to the government's current estimate of 34 kilotonnes.

"Bringing attention to this topic — hopefully that will lead to more emissions reductions, and more development of smart mitigation strategies," said Mary Kang, associate professor of civil engineering at McGill University, who led the research. 

There are about 470,000 non-producing wells across Canada, most in oil-rich Alberta but also in B.C., Alberta and Ontario. Regulators use varying terminology for these wells, like "inactive" or "abandoned," but they're generally wells that have ceased production and may require work to plug them and restore the area.  

About 68 per cent have been plugged in some way by their owners, while the rest are either unplugged or their status is unknown. The study estimated that about 50,000 wells in Canada are undocumented, most in Ontario.

The McGill researchers also found that a relatively small proportion of high-emitting wells were responsible for a large portion of the leaks. They suggest targeting those wells, along with repurposing wells for other uses, like producing geothermal energy, which would encourage monitoring them long-term and preventing methane leaks that pop up.

"For example, one well can emit as much as 100 wells combined," said Jade Boutot, a PhD student in civil engineering who was a co-author on the study.

"When we look at the characteristics of the wells, for example, their location or whether they're plugged or unplugged, we can identify the wells that are at a higher risk of emitting methane. And then we can prioritize them for remediation."

Environment and Climate Change Canada says it is reviewing the research and may include it while reviewing how it estimates methane emissions. The estimates are included in the government's annual greenhouse gas emissions report, which comes out around May.

Southwestern Ontario feels a long way from the centre of the oil industry in Western Canada, but it has a long history in oil and gas production. The first commercial oil well in North America started operating in 1858 in Oil Springs, Ont. The industry has left over 23,000 known legacy wells scattered throughout the region.

"A lot of the people that were exploiting those wells were actually small landowners and they drilled thousands and thousands of wells that were never recorded," said Stewart Hamilton, a geochemist and hydrogeologist who works for Montrose Environmental Group, a firm that works on well remediations.

He says he was not surprised at the McGill researchers' findings, given what he has seen with abandoned wells in Ontario that are leaking into groundwater and the surrounding environment, and causing headaches for local residents.

One such problematic well is in Norfolk County, Ont., about 15 kilometres from the shores of Lake Erie.