Natural gas producers have been ordered to review drilling plans for a liquids-rich corner of the Montney shale formation in northeastern British Columbia (BC) after an investigation blamed a Nov. 29 earthquake on hydraulic fracturing (fracking).

The order, from the BC Oil and Gas Commission (BCOGC), said a well by Canadian Natural Resources Ltd. triggered a magnitude 4.5 tremor and aftershocks of 4.0 and 3.4 near the industry''s operations base at Fort St. John.

No injuries, property or well damage resulted, but residents of the region reported shaking on the land surface. The tremor struck a sensitive, closely watched spot that the BCOGC calls the Kiskatinaw Seismic Monitoring and Mitigation Area (KSMMA).

After being suspended since the tremor, drilling is scheduled to resume on Jan. 5.  "Prior to commencing operations, all permit holders within KSMMA are required to submit revised induced seismicity assessments," said the BCOGC.

"Completions targeting the lower Montney formation within KSMMA appear to have increased susceptibility for induced seismic events and operators should be prepared to implement mitigation measures if seismic monitoring indicates an increase in the frequency or magnitude of events."

A BC government inquiry into shale drilling and production is scheduled to report by the time northern operations resume, following nine months of consultation with groups that have expert credentials in earth sciences and engineering.

The shale inquiry's mandate makes no reference to imposing a BC counterpart to bans against fracking in Quebec, New Brunswick and Nova Scotia.

BC Energy Minister Michelle Mungall described the study and potential regulatory refinements as contributions to "sustainably developing the province’s resources and creating jobs for British Columbians.

"We know British Columbians have questions about hydraulic fracturing. It’s our job to make sure that natural gas operations continue to meet world-class standards and best practices for environmental protection."

The inquiry announcement observed that fracking is a gas industry mainstay that has been used in nearly 12,000 BC wells to date. Forthcoming liquefied natural gas exports, supported by provincial government financial incentives, are projected to accelerate the practice.