The Alberta Energy Regulator said oil and gas companies working in the Duvernay zone near the Fox Creek area are to monitor for seismic events, and companies are to take certain outlined actions in case a seismic event registers greater than 2.0 on the Richter scale.
If a tremor above 4.0 is detected, companies are to immediately halt drilling and cannot resume without approval from regulators, AER said as it announced seismic monitoring and reporting requirements for hydraulic fracturing.
The monitoring and response requirements followed 18 seismic events with magnitudes in a range of 2.7-3.7 local magnitude near Fox Creek, Alta., during December 2014. In January, several events were recorded with magnitudes in a range of 2.4-4.4.
AER concluded some events possibly were related to hydraulic fracturing.
"While these seismic events have not impacted public safety, it is our job to take this precautionary step to ensure energy resources in this area are developed in a safe and responsible manner," said Jim Ellis, AER president and chief executive officer.
A subsurface order outlined a process that defined three specific stages at which operators are to take action in case seismic activity is detected, including that the AER be notified, that operators implement response plans, and at certain levels, cease operations.
On Feb. 3, AER released Bulletin 2015-03: Observed Seismicity and Oil and Gas Operations: Operators’ Responsibilities."
AER said the bulletin was to remind operators "of their responsibility to ensure well control and subsurface integrity at all stages of drilling, completion, and injection operations."
Fracturing has been used in Alberta since the 1950s, AER said, adding that it has been observed to induce subsurface seismic events since the 1960s although "most of these events have been too small to be felt or to cause surface impacts."
A subsurface order regarding monitoring and reporting of seismicity in the vicinity of fracturing operations requires:
- Before fracturing, licensees must assess the potential for induced seismicity caused by or resulting from fracturing operations and adopt, and be immediately prepared to implement, a response plan to address potential seismic events.
- Licensees will follow a process with staged thresholds. If no seismic events are observed, operators can proceed as per the AER’s usual requirements. The order requires licensees to immediately report to the AER seismic events of 2.0 magnitude or greater and invoke their response plan.
- The order requires operators cease fracturing altogether if a seismic event of 4.0 magnitude or greater is detected in the vicinity of their operations. In these circumstances, licensees will not be permitted to resume operations without AER consent.
Companies having assets in the Fox Creek area include Chevron Corp., Royal Dutch Shell, and Encana Corp.
