Numerous factors influence the potential for the HF and wastewater disposal activities used for natural gas development to cause seismicity, a phenomenon known as injection induced seismicity.
Geoscience BC has been funding research projects since 2012 to better understand when, where and why induced seismicity occurs. The results and ongoing research are informing decision-makers in industry, government, and communities so that the likelihood of future induced seismicity events can be reduced.
Arrays (networks) of seismographs – highly sensitive instruments that record the motion of the ground during an earthquake – are installed in BC’s Northeast Region to monitor seismicity. The McGill Array is a network of nine seismographs installed in the Fort St. John and Dawson Creek area. It is a critical piece of infrastructure for studying seismicity in the Montney Play, a gas-prone area within the Western Canadian Sedimentary Basin that contains some of North America’s most significant natural gas deposits. The McGill Array was installed in 2015 however the funding to manage its operation was due to expire in 2020. This project used funding from Geoscience BC and in-kind contributions from partners Natural Resources Canada, McGill University, Ruhr University Bochum and the BC Oil and Gas Commission, to maintain and operate the seismographs of the McGill Array and to provide real-time public seismicity data to operators, regulators, and the general public.
This Energy project fits under Geoscience BC’s Strategic Objective of ‘Facilitating Responsible Natural Resource Development’ and our goal to:
- Maintain joint research with partners examining seismicity induced by HF in northeastern BC to provide new science to better understand induced seismicity, mitigate risks and further improve regulation and industry practices.
Specifically, this project:
- Improved the availability of real-time seismicity data in BC’s Northeast Region;
- Researched source characteristics of significant events;
- Used artificial intelligence (AI) to analyze geological, tectonic, hydrological, geomechanical and operational parameters to better predict seismicity; and
- Improved the determination of earthquake locations.
Benefits of this research include:
- Public data about earthquakes in BC’s Northeast Region to inform regulator and others;
- Increased volume of peer-reviewed literature to build understanding of seismicity;
- Trained subject matter experts/highly qualified persons; and
- Information to help mitigate injection induced seismicity.
The McGill Array is in the Fort St. John – Dawson Creek area in BC’s Northeast Region.
What was Found
The project was divided into four work plans:
- Efficiently take over and manage the McGill Array and establish data sharing.
Two service programs were conducted in July and October 2021 to maintain system instrumentation. The monitoring stations are sending data to Natural Resources Canada for processing as well as the Incorporated Research Institutions for Seismology (IRIS) for public distribution.
- Establish the most comprehensive and accurate IIE catalogue for the region
During the project, 23,753 earthquakes were detected and located in the area which is defined as the Kiskatinaw Seismic Monitoring and Mitigation Area, with a magnitude of completeness of ~0.8. The catalogues containing this data have been published as Geological Survey of Canada Open File reports, and the data is available on IRIS. The research team also developed an AI-based earthquake location system that is capable of real-time monitoring of IIE without human intervention. Two reports (see Final Deliverables Appendix A and B) have been published on this technique.
- Delineate source characteristics of significant events in the region
The research team investigated the source characteristics of significant IIE in northeast BC and their relationship to injection parameters at nearby wells. Among the research published (see Final Deliverables Appendices C to I) it was found that ground motion intensity from shallow induced events can be higher than for deeper events, but the ground motion intensity decreases rapidly with distance and becomes less intense at distance than for deeper induced seismic events. The researchers also reported a new type of injection induced seismicity, named “earthquakes characterised by hybrid-frequency waveforms’, that have broader P- and S-wave pulses and lower frequency content.
- Delineate significant factors controlling the seismogenesis of IIE
This project phase aimed to establish a model that determined susceptibility for IIE in the region based on its geological, tectonic, geomechanical and hydrological conditions. This work conforms to that recommended by the BC Scientific Hydraulic Fracturing Review Panel report of 2019. The research demonstrated that the three top factors in order of importance are:
- Injection type: approximately 80% of all IIE recorded during the project were related to HF
- Regional structural geology: the number of seismic events per HF stage is greatest within the Fort St. John Graben filled with subvertical faults (structural feature)
- Stratigraphy: the number of seismic events per HF stage is highest in the Lower-Middle Montney, versus stratigraphically higher in the Montney Formation. The results for this research are published in Final Deliverables Appendices J to L.