REDWATER, Alberta — William Romaniuk stopped his tractor at the edge of his field and sniffed. A breeze came off the Saskatchewan River, rippling across rows of ripe wheat, but a caustic scent flooded his nose. An oil well between his crops and the river was leaking, and enough gas was flowing out of a pipe below the rusty pump jack that the farmer could smell gas and see it swirling in the air.
The site had been drilled in 1950 but hadn’t run since 2015. It was now spewing a blend of toxic, egg-smelling hydrogen sulfide and, quite likely, a much larger dose of odorless, flammable methane.
“They said, ‘don’t get too close to it,’” Mr. Romaniuk said, referring to the owners of the well. He put the tractor in gear and skirted the edge of the site, hoping he wouldn’t spark an explosion as he hurried to harvest.
Canada has committed to reducing its planet-warming carbon emissions and has singled out the oil and gas industry as the source of almost half of the country’s annual emissions of methane, a greenhouse gas that can have 80 times the heat-trapping power of carbon dioxide over 20 years. Alberta, the heart of Canadian hydrocarbon extraction, has set a goal of a 45 percent drop in the industry’s methane footprint from active infrastructure by 2025. But the inactive wells — the ones no longer producing oil or natural gas but many still lingering in suspension like zombies — may be as big a threat to the planet.
After decades of booms and busts, an enormous backlog of these inactive wells has built up, and it grows about 6 percent each year. There are now 97,920 wells, like the one on Mr. Romaniuk’s land, that are licensed as temporarily suspended, compared to the province’s 160,000 active wells. The inactive wells are unlikely to be switched on ever again but have not yet been decommissioned. No one knows how many are leaking methane and other pollutants.
“This is a problem that’s been festering for decades,” said Sonya Savage, Alberta’s energy minister.
In Alberta, the amount of methane and other potent greenhouses gases seeping from suspended wells has not been comprehensively studied. But research in British Columbia, another province with a long history of oil and gas development, revealed that more than a quarter of inactive wells in that province were leaking.
The normal life cycle of an oil or gas well is a little like that of a human: It is brought into life with expectation, produces vibrantly for a time, steadily declines and then is buried under clean soil.
Alberta’s oil boom started in earnest in the 1940s. The province was dotted with wells in the following decades, generating billions of dollars and hundreds of thousands of jobs.
When the price of oil crashed in the 1980s, thousands of wells quickly became unprofitable, and even though Alberta law places responsibility for closing those wells on the industry, many companies stopped taking care of the inactive wells. By 1990, there were more than 29,000 inactive wells in Alberta.
The Alberta Energy Regulator, part of the Ministry of Energy, reacted in 1997 with a rule that required companies to close a well after ten years of inactivity. But the industry pushed back and, in 2000, the agency allowed wells to be indefinitely suspended instead.
Depending on a well’s concentration of hydrogen sulfide, its condition and its proximity to homes, suspension can be as simple as putting a chain on the valve handles or as complicated as installing a cast iron and rubber bridge plug deep in the ground. Once a well is suspended for longer than 10 years, the plug becomes mandatory.
In Alberta, unlike in other oil fields including British Columbia and North Dakota, there is no time limit on how long a well can be suspended.
There are nearly 30,000 wells in Alberta that have been suspended for longer than ten years. According to the Alberta Energy Regulator, these wells are reactivated less than 0.2 percent of the time. One well near Calgary has been suspended since 1928.
William Morin, chief of the Enoch Cree Nation, drove past a grove where medicine men sometimes harvest sweetgrass, berries and buffalo sage on his way to survey an empty oil tank.
“When oil and gas was produced in the 40s, 50s, 60s, 70s, that’s how this nation grew in capacity and off of government funding,” Mr. Morin said, referring to the Enoch Cree Nation. “But then the oil and gas ran out.”
Out of 274 wells on Enoch Cree land, only 34 are currently pumping. The others are inactive: 43 are suspended and the rest have been decommissioned with a plug and a cement cap, but in many cases, equipment and waste has been left behind. The Enoch Cree Nation is in the process of measuring gas emissions from inactive sites and plans to use an infrared camera to detect…