Fluid injection during hydraulic fracturing caused a 4.6 earthquake north of Fort St. John this summer, the B.C. Oil and Gas Commission (OGC) has found.
The regulator released a report on the Aug. 17 quake Tuesday afternoon. Alaska Highway News received reports of shaking from the epicentre north of Wonowon to Charlie Lake, just outside Fort St. John.
"The event was the largest seismic event in B.C. caused by hydraulic fracturing investigated by the commission," OGC spokesperson Alan Clay wrote in an email. "We can't speak for (quakes in) other jurisdictions."
The quake occurred on a well site where Progress Energy was fracking, the OGC said in an industry bulletin. The company completed the job using reduced pumping rates.
According to the commission, a 4.6 quake will cause "brief shaking felt at the surface," but does not pose a risk to people or the environment. There were no reports of damage or injuries at the surface.
An earlier OGC report tied 231 seismic events in the Montney shale formation between August 2013 and November 2014 to oil and gas activity. Only 11 of those could be felt at the surface, and only two events in the Upper Montney were greater than 3.5 magnitude.
Progress Energy, a downstream subsidiary of Petronas, is among the most active drillers in B.C. The company drilled 203 wells in 2014—roughly 30 per cent of all wells drilled that year. The company is proving resources ahead of a final investment decision on Petronas's Pacific NorthWest liquefied natural gas plant in Prince Rupert.
According to minutes of a community meeting in Pink Mountain, Progress's activity contributes to roughly 2,800 jobs in the region. They plan to run between 10 and 15 rigs "consistently over the next few years."
The commission says it stepped up monitoring of seismic events in recent years, and now requires any driller that causes an earthquake greater than 4.0 magnitude to stop operations.
The well did not leak, Clay said.
This summer, the OGC announced a 4.4 quake in August 2014 was also caused by Progress fracking operations. It was among the strongest fracking-induced quakes ever recorded at that time.
"The commission recognizes these events are a concern to the public and is working to ensure there is no risk to (the public), by implementing effective regulatory measures and mitigation procedures to reduce the frequency and magnitude of induced events," Clay wrote.
Progress spokesperson Stacie Dley said the company has 17 seismic monitoring stations in the area.
"We will continue to be diligent and monitor our activities and adjust our operations as needed, such as decreasing fluid volume and pressure," she wrote in an email.