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When wells are decommissioned, cement plugs are installed and well casings are cut a couple of metres below the ground, but this does not stop buoyant methane gas from gradually working its way to the surface, both from within and outside the casing.

Jeff McIntosh/The Canadian Press

Richard Jackson is a fellow at Geofirma Engineering and an adjunct professor at the University of Waterloo. Maurice Dusseault is a professor of geological engineering at the University of Waterloo. Christopher Holly is an independent consultant and a former executive director of energy technical services at the Alberta Department of Energy.

Oil and gas development has benefited Canada’s economy – but has left a costly environmental legacy.

Across Canada, there are more than 550,000 wells – active, inactive and decommissioned. Some are slowly leaking, mainly methane emissions, into the atmosphere or into shallow groundwater.

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Inactive and decommissioned wells that no longer have fiscally viable owners are deemed “orphan wells.” Most inactive wells won’t return to production and will become orphan wells if their owners go bankrupt. Tougher regulations promote this trend. Then the cost of remediation falls to the provincial taxpayer.

An informed estimate indicates there are about 40,000 leaky wells in Alberta, of which about 40 per cent are orphan wells. Alberta has 90,000 inactive wells and added 2,000 to its orphan well inventory in 2019. There are orphan wells in Quebec, New Brunswick, Nova Scotia, southwestern Newfoundland, even Prince Edward Island.

In Southwestern Ontario, leaking methane generates hydrogen sulphide, or “rotten-egg gas,” so health and safety risks arise – particularly with orphan wells dating back more than 50 years, when decommissioning practices were rudimentary. In Norfolk and Haldimand counties, 87 per cent of the 8,600 gas wells are inactive and identified as “abandoned” or “unknown,” rather than as orphan wells, as they’re called in Alberta.

If Ontario is any guide, then Canada’s inventory of energy wells that will become inactive by 2050 will grow to 500,000 wells, many of them without owners. A program to address the remediation of these wells has numerous benefits – both economic and environmental. So where do we go from here to mitigate long-term costs and environmental impacts?

First, to fix a problem, a correct diagnosis is needed. Symptoms and processes depend on historical practices, local geology and the presence of subdivisions and water wells.

Second, risk analysis is vital because consequences guide decision-making. A leaky orphan well in a remote part of British Columbia has different societal and health effects than a leaky orphan well under a suburban residence near Calgary. A well emitting a cubic metre of methane a day, about that of two cows, is different than one emitting a hundred cubic metres a day.

Third, rational and effective solutions must be developed for specific conditions, then implemented.

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When wells are decommissioned, cement plugs are installed and well casings are cut a couple of metres below the ground, but this does not stop buoyant methane gas from gradually working its way to the surface, both from within and outside the casing.

Subsurface gas leakage can sour groundwater in water wells and cause domestic wells to become gassy. Leaking methane that enters the atmosphere contributes to the greenhouse effect. Urban sprawl moves people to build and purchase houses above old oil and gas fields and adjacent to leaky orphan wells.

In northeastern B.C. gas fields, about 10 per cent of all active and suspended gas wells leak methane; in Saskatchewan and Ontario, the number is closer to 20 per cent. These are likely to be underestimates for orphan wells because it takes years for buoyant gas to migrate up well bores to continually discharge at the surface; it takes years for well-bore-casing corrosion and cement-seal deterioration to develop; and it takes months to detect gas that seeps into vulnerable aquifers around leaky wells.

So true emission rates from orphan wells remain largely unknown and, with aging, these wells are more likely to leak methane and possibly hydrogen sulphide. By 2050, Canada can expect to have about 100,000 leaky orphan wells unless we act now.

The Alberta government recently asked Ottawa for assistance for its orphan well program. As costs for the oil and gas industry go up, there will be a corresponding increase in the number of orphan wells, as some producers will find the new economic and regulatory climate unsustainable. A nationwide federal-provincial orphan well program would help all provinces, especially Alberta and Ontario, address their particular emission problems. It could also sponsor research and technology development to accomplish meaningful reductions in well leakage.

The problem of orphan wells is ramping up, and provincial remediation programs need additional funding. Carbon tax receipts might appropriately be used for this purpose. Federal matching funds would help reduce atmospheric emissions and groundwater contamination, sustain a troubled sector of the economy and acknowledge the vast contribution Alberta has made to federal coffers – more than $6,000 per capita annually in recent years.

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The polluters who created orphan wells no longer exist and therefore cannot be expected to pay. Just as nuclear reactors need effective decommissioning, so do orphan energy wells.

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