Companies that frack less aggressively for oil can lessen the number of earthquakes but not necessarily their magnitude, a London researcher has found.
Low-volume fracking found still dangerous
Gail Atkinson, a professor in Western University’s faculty of science, has found oil companies that reduce the volume of liquids they use to displace oil lack the evidence needed to show they won’t trigger a major earthquake, a finding that regulators may need to consider when deciding whether to allow fracking closer to population centres - writes lfpress.com.
“This is an important finding because some previously held theories propose that there is a relationship between the largest magnitude of the earthquake and the injected volume, but what we have found is that the maximum magnitude isn’t what’s being controlled by the volume,” said Atkinson, the nanometrics industrial research chair in hazards from induced seismicity.
The use of fracking has grown in the past decade because it allows oil companies to drill a single vertical shaft until it reaches a bed of oil, then drill a horizontal shaft to extract that oil less expensively than the traditional method of drilling multiple vertical shafts, Atkinson said.
But when companies pump liquids through horizontal shafts, the pressure triggers earthquakes, previous research has found.
The newest research by Atkinson, published in a leading journal, Science, tapped into more detailed data on how liquids are used to frack near Fox Creek in central Alberta that holds Canada’s largest marketable reserves of oil.
“Industry needs to be aware that controlling the volume doesn’t provide a guarantee on the maximum magnitude,” says Atkinson, who teamed with researchers at the Alberta Geological Survey, the University of Alberta, the University of Calgary and Natural Resources Canada. “There is still a possibility for larger events, so industry still needs to be very careful where they conduct hydraulic fracturing operations. They have to stay away from critical infrastructure to prevent a damaging event.”
When the number of earthquakes increases because fracking, while the vast majority will be small in scope, the greater their number, the greater the chance that one could be substantial, she said.
“There is some indication that industry is getting better at limiting induced earthquakes as the number of induced events has gone down in a number of jurisdictions, like Alberta and Oklahoma, over the past year,” says Atkinson. “For a while, every year, the largest event that was induced was the largest to date and we haven’t seen anything bigger this year than we have before. That may be a sign that industry is figuring some of these things out.”
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