Fracking caused 11 earthquakes in the Montney basin area surrounding Fort St. John and Dawson Creek between August 2013 and October 2014 that could be felt on the surface, a new B.C. Oil and Gas Commission report states.
However, no person or property was injured as a result of those earthquakes, according to the report.
The number of earthquakes is associated with development, according to an oil and gas industry executive.
“I would think that the percentage of induced events will be definitely scaled back or forward with activity counts,” said Brad Herald, vice-president of Western Canada Operations for the Canadian Association of Petroleum Producers (CAPP).
The amount of seismic events caused by oil and gas operations that could not be felt on the surface was much higher. There were about 220 seismic events in the Montney in those circumstances.
The earthquakes ranged from 1 to 4.4 on the Mercalli scale. The Mercalli scale, which is used in place of the Richter scale, measures earthquake magnitude.
According to the U.S. Geological Service, 1 to 3 magnitude quakes can rarely be felt on the surface. The majority of the earthquakes were in this category. A 3 to 3.9 magnitude quake can be “felt only by a few persons at best, especially on upper floors of buildings.” Less than 10 of these events were in this category. A 4 to 4.9 earthquake can be felt indoors by many, and outdoors by few. It could also wake some people up. Only one or two events were in this category.
The majority of the seismic events — about 84 per cent — came as a result of regular fracking well operations. The other 16 per cent were caused by disposal wells.
But the report stated that two disposal wells created 38 seismic events.
B.C. has 104 disposal wells within its borders.
Hydraulic fracturing — the process used to extract natural gas from deep underground — has long been linked to earthquakes.
“I don’t think it’s a surprise to us,” said Herald. “We monitor those active areas globally in terms of induced seismicity to hydraulic fracturing … we do understand that in some instances there’s induced seismicity related to hydraulic fracturing.”
Last year, his group came forward with a list of operating guidelines to help operators deal with the possibility of earthquakes.
“Industry takes this very seriously and we understand the public has concerns about the issue,” Herald added. “There has been no injuries and no damage to property, but it’s still a felt event, they can be unsettling for people at the surface.”
He further explained that the likelihood of fracking-caused earthquakes would depend on where activities were taking place. In 2012, fracking was linked to earthquakes in the Horn River basin — the area around Northern Rockies Regional Municipality.
But the Montney basin area has seen more development. By August 2014, close to 90 per cent of fracking operations occurred in the Montney area, the OGC report stated.
“We want to understand where the events are occurring,” said Herald.
Questions sent to the OGC about whether or not they expected these events to increase either in strength or numbers were not returned as of press time.
Report recommendations supported by CAPP
The report also made some recommendations about seismic events caused by fracking.
Three included identifying pre-existing faults, a dense array deploment requested in certain areas where more information is needed, fault zone avoidance for fracking operations, and early flow back of fluids used in fracking.
Herald said that his group was supportive of the recommendations.