Industry takes human-triggered earthquakes seriously
Regulations for earthquake activity triggered by natural gas development
Canada’s natural gas industry and provincial regulators take the issue of induced seismicity, or human-triggered earthquakes, very seriously and understand that Canadians have concerns.
During hydraulic fracturing operations, rock layers kilometres below the earth’s surface are cracked or fractured to enhance well productivity. The energy released through this process routinely generates microseismic events too small to be felt by people at the surface (ML<0), but that can be detected using sensitive seismic monitoring equipment. Occasionally, larger events occur (0<ML<3) which may be felt by some at the surface in relatively close proximity to the operations (a few kilometres). In very rare instances, ML>3 seismic events are induced and may be felt by more people over a larger area, but are still unlikely to cause damage to structures that meet Canada’s area based National Building Code requirements.
In B.C., the Oil and Gas Commission (BCOGC), oversees regulations related to hydraulic fracturing and responds to seismic events as soon and they are detected. Regulations require the operator to immediately report seismic events with ML>4 or unusual ground motion experienced by people within three km of their operations. If the operator’s well is determined to be the likely cause of the event (or ground motion), then the operator must suspend hydraulic fracturing operations immediately. Operations can only be resumed with the implementation of a mitigation plan. This plan and the ability to resume operations must be approved by the regulator – the OGC.
In Alberta, the Alberta Energy Regulator (AER) uses a compliance dashboard for seismic monitoring and reporting requirements for hydraulic fracturing operators in the Duvernay near Fox Creek. The AER uses a ‘traffic light’ system that requires operations to report seismic events if they are greater than magnitude 2.0 or greater and operations must cease if the event measures magnitude 4 or greater. The AER will allow operations to resume once they are satisfied with the actions taken by the operator to reduce the likelihood of further seismicity.
Monitoring ground movement
To ensure safe operations and responsible development of natural gas, the Alberta Energy Regulator monitor ground movement with an extensive network of more than 40 seismic monitoring stations. The British Columbia regulator, the OGC, monitors the Canadian National Seismograph Network (CNSN) for seismicity and the network in B.C. has been recently upgraded to add nine additional seismograph stations in northeast B.C. bringing the total to 11 in the area. Independent data collected by natural gas producers in the region is also shared with the regulator.
In B.C., the OGC has new requirements for ground motion monitoring that require adequate monitoring during hydraulic fracturing activities and the submission of a ground motion monitoring report within 30 days of completing fracturing activities.