They have shown that fracking in the Duvernay field can be done safely without causing reportable earthquakes. When the initial project for the 2-21 pad was proposed in 2017 and presented to the residents of Fox Creek, Chevron representatives were met with an overwhelming response of concern from the public concerning the close proximity of the well paths to town limits and the fears of potentially damaging earthquakes during the fracking stages. After several adjustments and repositioning of the well paths, operations commenced successfully.
From 2015 to 2019, there have been 1,134 reports of induced seismicity or earthquakes in the Fox Creek region, according to the Alberta Energy Regulator (AER) website. In light of the numbers of earthquakes caused by fracking, the AER created area-specific seismic protocols that companies must follow for their fracturing operations. It’s only been in the last four years that the earthquakes have drawn the attention of the media, regulators, energy companies and the public after a Repsol Oil & Gas fracking operation triggered Canada’s potentially largest induced earthquake measuring 4.8 magnitude.
Since the January 2015 earthquake measuring 4.4 magnitude, seismic monitoring and reporting are part of the AER’s Subsurface Orders during fracks and works on the traffic light signal with reporting and operating protocols for yellow, green and red zones. To assist with monitoring for seismic activity during fracking, the AER uses the Regional Alberta Observatory for Earthquake Studies Network (RAVEN) monitoring stations in conjunction with other networks operated by research organizations. Within the monitoring station is a seismometer, which measures ground vibrations. The vibrations are digitally recorded and processed to determine location and magnitude. The AER suggests a magnitude reading of less than 3-4 could feel like vibrations of a passing truck, while the 4-5 magnitude range would be noticeable in terms of sound, vibration and overturning of unstable objects.
As Chevron takes the potential for harm to persons, the environment and safety very seriously, the company has taken AER’s seismic protocols to a higher level, which would allow for early mitigation and management of any seismicity during fracking. As part of the company’s mitigation, they’ve enhanced the AER requirements and lowered the threshold for magnitude numbers in which operations must alter or cease. In conjunction with AER’s RAVEN monitoring stations, the monitoring station in Fox Creek and the Regional array station, Chevron had eight additional micro-seismic array stations added to the 2-21 pad itself. In addition to adding extra monitoring stations, Chevron set its own traffic light protocol numbers which are 10 times more conservative than what’s required by AER standards.
Since completions began, the FOXCA and RAVEN systems have picked up zero induced seismic activity; however, the micro-seismic array did get readings. There were 31 in total, but as they were well below AER’s 2.0 magnitude threshold of what can be felt, they would have gone undetectable if it weren’t for using the new micro-seismic array. Despite the number of detections, this advanced technology to micro detect picked up magnitude ranges in the negatives and the largest event, which only reached 0.12 magnitude, which equates to the energy of a home run hit. By utilizing the micro-seismic array during operations, Chevron is well ahead of the game and can slow or stop the operation well before any activity is felt from the government systems, ultimately preventing an induced earthquake.
Vicki Winger, Local Journalism Initiative Reporter, Whitecourt Press