Wheatley explosion could be 'tip of the iceberg' in Ontario given number of abandoned wells: expert

An expert on oil and gas wells in southwestern Ontario who presented at a national conference outlines the issues with abandoned wells in the wake of an explosion in Wheatley, Ont., that sent seven people to hospital.

Explosion sent 7 people to hospital, reduced buildings to rubble

Two buildings in Wheatley, Ont., were reduced to rubble after an explosion on Aug. 26. Seven people were also sent to hospital. (Jacob Barker/CBC)

An explosion in Wheatley, Ont., believed to be caused by an abandoned gas well is the extreme example of what can happen if such wells are not properly plugged, according to an expert hydrogeologist who has researched oil and gas wells in southwestern Ontario.

"It can happen anywhere in southwestern Ontario," said Dick Jackson, an adjunct professor at the University of Waterloo, who last year gave a presentation at a national geological convention about the dangers of the province's abandoned wells.

Seven people were sent to hospital and two buildings were destroyed in Wheatley when an explosion rocked the downtown core last Thursday, just over an hour after high readings of hydrogen sulphide were recorded.

The town of 3,000, located about 65 kilometres southeast of Windsor, Ont., had experienced three previous gas leaks in the area in recent months.

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CBC News spoke with Jackson to get a sense of how many abandoned wells there are in the province and what kind of risk they might pose for other communities. 

How many abandoned gas and oil wells are in Ontario?

"In Ontario, the province knows within 200 metres where 27,000 of these oil and gas wells are. About 3,000 are active, the other 24,000 are abandoned," said Jackson. "There are about 3,000 where we probably don't know where they are."

He found three recorded wells in Wheatley through the Oil, Gas and Salt Resources Library, which collects and publicly posts details of wells in Ontario using provincial records. 

"But their location wasn't known within an area of 200 metres. Very uncertain. Clearly the town got built after these wells got built," he said. 

The recorded wells include:

  • An abandoned private gas well marked at Talbot Road East and Erie Street North, which records show was drilled in 1896 and plugged in 1965.
  • An abandoned private gas well marked between Chestnut Street and Moor Street, which records show was drilled in 1897 and plugged in 1965.
  • A private gas well marked near Little Street North and Elm Street, which does not include any details about its operating status or when it was drilled. 

A fourth well sits just outside Wheatley's core:

  • An abandoned natural gas well marked near Julian Street and Eastman Avenue, which records show was plugged in 2015 but there were no details on when it was drilled.

How are these wells plugged?

Anyone can access information on known wells through the Ontario Oil, Gas and Salt Resource Library.

The well that records estimate is closest to the Wheatley blast site, at Talbot Road East and Erie Street North, was plugged with cement and gravel, according to records.

Jackson said plugging practices were "very primitive" before the 1970s.

"It was a poorly understood technology. They would put tree trunks down them. Cement. Gravel. And they would pound lead in," said Jackson.

"Once we plug and abandon these wells, we figure they're not going to leak. But some of them will. No question about that."

Why are leaks so hard to find?

Jackson said the issue is twofold: eroding well casings and cement plugs create opportunities for the sites to leak, and the removal of those casings for other projects makes the sites hard to find.

"You're getting breakthrough of this deep gas coming from these depleted oil fields," said Jackson.

He said even though an oil reservoir might have been depleted through decades of pumping, it will slowly re-pressurize over time.

Finding these wells has become difficult, he said, because it was popular practice to remove the top sections of the casings in order to repurpose them for ships during the Second World War.

Dick Jackson, a hydrogeologist and adjunct professor at the University of Waterloo, said that abandoned oil and gas wells are a provincial responsibility. (Chris Ensing/CBC)

Removing the surface casing makes it extremely difficult to detect the abandoned wells. 

"There's no magnetic signal that your geophysicist can hit. Then trying to re-plug them becomes horrendously expensive," said Jackson. 

"The problem in a town like Wheatley is you got so much steel around the town in piping that the geophysicist isn't going to be able to figure out what's an old abandoned oil well and what's a new piece of steel piping going to a gas station."

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Where does the toxic gas come from?

The deterioration of the well casings open up pathways for methane gas trapped below the surface to mix with gypsum rock, creating the toxic and sometimes-deadly hydrogen sulphide gas. 

"If you drilled 100 years ago, by now, those casings are rotted out. You're getting gas moving up from the basin," said Jackson.

Methane dissolves the gypsum, releasing sulphate, which the methane then reduces into hydrogen sulphide. 

"It's like a big chemical reactor," said Jackson.

Who is responsible for these abandoned wells?

The Ministry of Natural Resources is responsible for Ontario's abandoned wells, but according to Jackson, the province is in no position to do the plugging work with speed. 

"Under something called the abandoned works program, if you can satisfy the criteria of the abandoned works program and you float to the top of their hazardous criteria list, you will get your well plugged," said Jackson. 

"But don't hold your breath."

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Professor Dick Jackson said that the ministry of natural resources in Ontario is responsible for abandoned gas wells.

He said the ministry has a duty of care when it comes to abandoned wells in Ontario.

"They are depleted in expertise and they are depleted in funding, I believe," said Jackson, noting the most experienced people have retired in the last decade. 

"I don't think the Ford government has really put a lot of money in the abandoned works program." 

Jackson added, however, that funding is important because what happened in Wheatley could be the "tip of the iceberg" when it comes to issues with abandoned wells.

Costs of plugging up a well difficult to predict 

Plugging abandoned wells is difficult, Jackson said, because of the toxic chemicals that can be found after years of neglect. 

He recently asked a group that works in the industry for an estimate to plug an abandoned well for a project he's consulting on. "I got numbers from $30,000 to $200,000 per well.… We just don't know [the scale]," said Jackson.

Jackson said the work in Wheatley is "not going to be cheap." 

"They're going to spend a million or two by the time they've found that well and essentially plugged it and figured out what they're going to do to prevent any of these other wells around Wheatley from leaking," he said.

"It's an enormous job. It's a legacy problem."