This text is part of the special Research section: climate issues
Abandoned oil and gas wells number in the millions in countries that have practiced oil and gas exploitation. In Canada, there are at least 400,000. “And it’s probably more,” explains Mary Wang, assistant professor in the Department of Engineering at McGill University, “because these abandoned wells are very poorly documented. Some are even orphans, in the sense that we have no idea who could have owned them. »
Why were these wells left abandoned? “There are two main reasons,” continues M.me Wang: Either the well went dry or the company went bankrupt. Also, there is a practice adopted by large oil and gas producers of disposing of wells whose reserves are considered insufficient for profitable marketing for them. The buyers, smaller players, simply shut down once the reserve has been exploited. »
The problem, and it is a big one, is that these abandoned wells are not sealed; We basically just close the valve. In the absence of sealing, they allow harmful fumes to escape, such as methane, a powerful greenhouse gas, and hydrogen sulphide, a flammable gas, harmful to humans. And since there is no law requiring the owners of these wells to seal them, the task falls to governments. In the United States, under President Biden, Congress passed a bipartisan infrastructure bill in 2021 that provides $4.7 billion for plugging abandoned wells. “It may seem like a huge amount,” says Mary Wang, “but it’s a drop in the ocean given the number of abandoned wells in the United States. »
Seal, certainly, but list before
Mary Wang is part of a research team that looked into the case of abandoned wells in the United States. Why in the United States and not Canada? “It’s because in Canada, if we have a lot of data on active wells,” replies M.me Wang, we don’t have any on inactive wells. On the other hand, in certain American states, such as Pennsylvania and Oklahoma, there is public data on abandoned wells. »
The research team therefore examined 80,000 abandoned wells according to their location and the socioeconomic data of the region where they are located. “The study found that 40% of these 80,000 wells are located within 1 kilometer of a community inhabited, often by Indigenous or Latin Americans. In addition, a third of these wells are located less than 1 kilometer from a private groundwater well. In total, this represents 4.6 million Americans, or 13% of the population, who live within 1 kilometer of one of these 80,000 abandoned wells. » It’s hard to imagine the number of Americans who are in a similar situation when we consider all the abandoned wells across the country.
An innovative solution
The simplest solution to the problem of abandoned and orphaned oil and gas wells is to plug them. We dismantle the infrastructure left behind, seal the well and let nature take back its rights.
Mary Wang believes that it is also possible to use these wells for useful purposes. “This does not apply to all abandoned wells, some date from the end of the 19th centurye century and are in too poor condition. But there are some, newer and in better condition, which could, if they can be sealed, be converted for carbon storage. »
In addition, since they are already dug, these wells could be used as a source of geothermal energy if their location is near an industry or an inhabited community and connection to the well is thus possible. “Also, these wells are often located in an open and windy location, which makes them an ideal location for a wind farm,” says Mary Wang.
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