Chevron Canada has confirmed that "a magnitude 4.4 seismic event was recorded by seismic monitoring arrays operated by Chevron Canada and Natural Resources Canada" in the Duvernay shale near Fox Creek, Alberta on Saturday.
It's the second record-breaking industry-reported tremor to hit the region in a year. In January, industry triggered a 4.4 magnitude earthquake in the Duvernay shale.
That event forced the Alberta Energy Regulator to adopt a "traffic light system" to regulate seismic events in the region. The system requires companies to report events greater than a magnitude of 2.0, and to shut down operations once a 4.0 magnitude event is observed nearby.
As a result of the new regulations, Chevron reported the earthquake to the regulator and shut down operations at a natural gas well pad located approximately 27 kilometres south of Fox Creek.
However, the regulator has given the company permission to finish securing the well before it temporarily suspends operations at the site.
A spokesman for Chevron Canada, Lief Sollid, said the company "was installing production tubing in a well on the pad at the time of the event. Multi-stage hydraulic fracturing operations were completed on the eight-well pad on June 5."
Hydraulic fracturing, the cracking of rock with highly pressurized fluids, can trigger an earthquake days after the event.
Sollid added in an email that "no injuries, property damage or environmental impacts have been reported as a result of the event."
Since 2013, when companies started to fracture the deep shale with one to two-kilometre-long horizontal wells, the region has experienced a wave of tremors.
The Duvernay shale, or what stock promoters have dubbed the "new millennium gold," covers a 56,000 square mile region and contains natural gas liquids. An average horizontal well may cost $15 million to drill.
Chevron is part-owner of the Kitimat LNG project, which will operate as an export facility for unconventional natural gas that has been fracked and extracted from British Columbia's Liard and Horn River basins.
'Prolific' events: study
According to a study published in Geophysical Research Letters, industry drilling in the Duvernay triggered more than 160 earthquakes ("a new sequence of events") near Crooked Lake between 2013 and January 2015, about 30 kilometres west of Fox Creek.
The researchers found that the tremors were related to activities at "multiple horizontal wells instead of just one," and that industry had authored the "most prolific and largest magnitude fracking events to date."
The scientists reported that an "unwanted flow of hydraulic fracturing fluid into a preexisting fault system" most likely triggered the events: "Overall, we find that seismicity in the Crooked Lake Sequences is consistent with first-order observations of hydraulic fracturing induced seismicity."
According to a presentation by Dan Walker, a geologist with the BC Oil and Gas Commission, hydraulic fracturing and waste water disposal have triggered more than 1,000 earthquakes in northeastern B.C. ranging in magnitude from 1.0 to 4.3 since 2004. More than 20 events were reported "felt" at the surface.
Industry-made earthquakes are a concern, says Walker, because they can cause property damage, pose a hazard to the public, contaminate groundwater and damage oil and gas wells.
In a 2014 presentation to the Yukon government, the Fort Nelson First Nation, whose land has been heavily fracked by industry, complained that the technology was poorly regulated and can have "significant adverse impacts on land, water and treaty rights."
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