B.C. survey of abandoned gas wells released to mixed reviews

A landmark government study of abandoned natural gas wells in B.C. has found less than one per cent are leaking planet-warming methane into the atmosphere but some experts in the fieldsay they're not convinced the provincialenergy regulator's surveyis representative of the actual situation on the ground.

The regulator commissioneda helicopter to fly 90 to 150 metres above 1,221 wells across the province between 2017 and 2023, with a laser directed toward each site.

A laser passing through methane gas would reflect a weaker signal to a detector in the helicopter indicating a leak.

Results published at the end of May indicated that 25 of the wells surveyed showed possible signs of a leak.Of those, the regulator confirmed six were leaking methane. It is still investigating nine.

Aaron Cahill, a geoscientist at Heriot-Watt University in the U.K.who has previously worked with the regulator, says the initiative can find the largest leaks but might miss what's actually happening on the ground.

"I'm healthily skeptical of these types of surveys," Cahillsaid. "I know what I see on the ground, and I find it challenging to believe you would definitely see that from a helicopter."

The report from the B.C. Energy Regulator indicates B.C. hasabout7,700 wells that have already been plugged and abandoned.Another 7,500 are suspended or otherwise inactive. About 16,000 more wells, many of which are fracking, will need to be decommissioned in the coming decades.

To decommission oil and gas wells, the regulatorrequires site owners to seal wells with concrete plugs, clean up contaminants and restore local ecosystems.

However, Mary Kang, a civil engineering researcher at McGill University, said even if an operator properly seals a well, earthquakes, land disruptions, and other factors can cause plugs to fail years after they are decommissioned.

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The survey included wells that had yet to be plugged.

In an email to CBC News, Lannea Parfitt, a spokesperson for the B.C. Energy Regulator,said it studied primarily natural gas wells, while oil wells made up a "small proportion" of the survey.

"The findings from this program support the assertion that well decommissioning requirements are robust and effective," Parfitt said. She added the flyover helps the regulator monitor wells in hard-to-reach or remote places.

But oil and gas well researchers say the number of leaks could be much higher. In a separate study, Kang and researchers compared the regulator's flyover data to an on-the-ground assessment.

They found the regulator's airborne survey method likely misses methane emission rates of up to 450,000 milligrams of methane per hour. roughly equivalent to the emissions from driving 52 kilometres in a gas-powered car, according to the United States Environmental Protection Agency.

On some occasions, Kang and co-researchers say they found the survey missed wells leaking methane at 10 times that rate.

Cahill said weather, temperature and even the downdraft from the helicopter can affect how methane flows from the well, skewing the data.

Nonetheless, he said the flyover survey is important. While an inspector may only be able to attend one or two wells per day, Cahill said a flyover survey can monitor hundreds of wells in the same period.

"They're going to see the big leaks," Cahill said. "But I wouldn't hang my hat on that being the definitive answer to what's going on in B.C."

Parfitt said the regulator conducts 4,500 on-the-ground inspections of oil and gas infrastructure each year, including some decommissioned wells. She said the office is committed to monitoring decommissioned wells and plans to continue its flyover survey in the coming years.

Kang noted there are no legal requirements for the regulator to monitor decommissioned oil and gas wells.

"Everybody can always do more," Kang said. "But I will say that [B.C.] is doing more than what other provinces are doing."