The Alberta Energy Regulator has cited an energy company for causing a series of earthquakes, including the largest recorded tremblor in the province’s history.
The environmental protection order issued against Obsidian Energy Ltd. Thursday came the same day a scientific paper was published showing those earthquakes were caused by industry activity — not natural causes, as the regulator initially suggested.
In November, parts of Alberta near the northwestern town of Peace River were rocked by a series of quakes culminating in one that reached a 5.6 magnitude.
Residents reported being knocked to their knees. The earth was pushed upward by more than three centimetres — enough to register on satellites.
Then on March 16, more earthquakes were recorded in the same part of northern Alberta. The Alberta Energy Regulator said the seismic event was reported approximately 42 kilometres southeast of Peace River with a local magnitude of 5.09.
“This event was caused by wastewater disposal,” said Ryan Schultz, a Canadian seismologist who helped conduct the research while at Stanford University in California.
Oilpatch techniques, such as deep disposal wells that inject wastewater kilometres underground, can induce earthquakes.
One such well located near the earthquake site, used to dispose of water used in oilsands operations, has injected more thanone millioncubic metres of wastewater down about two kilometres.
After the record-breaking quake occurred, the Alberta Geological Survey, a branch of the province’s Alberta Energy Regulator, attributed it to natural causes.
The centre of the quake, then estimated to be six kilometres underground, was thought too deep and too far away from oilpatch activity in time and space to have been generated by industry.
Not so, said Schultz.
A closer and more thorough look at the data brought the centre of the quake up to about four kilometres beneath the surface. That figure is now reflected in the regulator’s catalogue of Alberta quakes.
Similarly, a look at previous research on so-called “induced seismicity” revealed long lag times between deep-well water injection and earthquakes.
A previous disposal site in Alberta started quaking three years after pumping began, Schultz said. A Dutch disposal well didn’t start causing earthquakes for decades.
As well, history shows deep water disposal can cause earthquakes up to 20 kilometres away. Alberta’s November earthquakes were nowhere near that distant.
“The clusters of earthquakes were right on top of a deep disposal well,” Schultz said.
His paper, co-authored by scientists at the University of Alberta as well as Natural Resources Canada and published in Geophysical Research Letters, suggests that the injected water forced itself between the two sides of a fault deep in the earth.
That water was enough to reduce the friction holding the two sides together and eventually resulted in a slippage that shook the surface.
Statistical analysis of correlation between the quakes and the underground pumping was conclusive, Schultz said.
“We had a confidence somewhere between 89 and 97 per cent just in the timing,” he said. “There is enough information to start making these kinds of links.”
AER issues environmental protection order to Obsidian Energy
On Thursday evening, the AER said earlier in the day it issued an environmental protection order under sections 113 and 241 of the Environmental Protection and Enhancement Act (EPEA) to Obsidian Energy Ltd.
The AER said it issued the order due to a “series of induced seismic events” that happened between November 29, 2022, and the quakes last week in the Peace River region.
The regulator said the AGS investigation, which at first chalked the quakes up to natural causes, has now concluded they were caused by Obsidian’s disposal operations.
“The disposal operation includes a well authorized for the disposal of water via injection into the Leduc Formation. The unique geological features of the area also contributed to the seismic events,” the AER said in a statement to Global News.
“While there is no evidence of damages or injuries from these events, this order and subsequent investigation reflects our commitment to Albertans to ensure safe, efficient, orderly, and environmentally responsible development,” the statement said.
“The order is intended to prevent future events and protect Albertans.”
Under the order, the AER said Obsidian must:
- Submit plans and take actions acceptable to the AER to reduce the frequency and magnitude of the events
- Establish seismic monitoring in the surrounding area that detects events above a local magnitude of 2.0
- Install accelerometers at strategic locations within a 10-kilometre radius of the disposal operation to measure vibration
The oil and gas producer pumps about 33,000 barrels of oil equivalent a day.
How will human-caused earthquakes affect carbon capture plans?
Schultz said the findings could have big implications for Canada’s and Alberta’s climate change plans.
Both jurisdictions favour reducing the climate impact of the province’s energy industry by pumping vast amounts of waste carbon dioxide deep underground, much as wastewater is injected.
So-called carbon capture and storage could have the same seismic effects as deep wastewater disposal, Schultz said.
“If carbon capture is going to be done at a scale that is going to combat climate change, then significant amounts of volume need to be put in the ground,” he said.
“You might expect then also getting these types of earthquakes the more volume that you store.”
That doesn’t necessarily mean carbon capture and storage is a bad idea, he said, but it means a lot more seismic monitoring needs to take place around the sites to keep track of what’s happening deep in the earth.
“This could be an issue,” Schultz said. “Monitoring will tell.
“You need to be able to see what is going on.”
— With files from Karen Bartko, Global News