The Need
In the report Investigation of Observed Seismicity in the Horn River Basin, the BCOGC recommended augmenting the Canadian National Seismographic Network (CNSN) to improve knowledge of the effects of induced seismicity by monitoring seismic events created by oil and gas operations that are related to HF and wastewater disposal (WD). In addition, in 2019 the Province of BC released the Scientific Review of Hydraulic Fracturing in British Columbia report recommending that seismic monitoring be augmented in BC’s Northeast Region. While the first aforementioned report speaks to the Horn River Basin specifically, the hydraulic fracturing review report identified a need for additional seismic monitoring in the BC Montney play area.
Project Benefits
Data regarding seismic events in Northeast BC are being used by the BCOGC for ongoing review and development for responsible HF and WD operations. This information has also been used by the oil and gas sector to improve completion practices and is also used by local communities and First Nations. A fundamental goal of BCOGC is to understand and quantify the emerging seismic hazards from oil and gas activities.
The consortium produces an annual induced seismicity report that provides a detailed review of the previous year’s seismicity, including an Earthquake catalog. Research of specific geographic areas and/or of associated induced seismicity technical studies are also included in the report. See the Deliverables section below for links to all reports.
Location
Eight stations were installed in the first two years of the program, to support two existing stations. Since then, additional stations have been added, with the network scale fluctuating each year as other seismic monitoring partners come online or are removed. The majority of the stations lie in the area between Dawson Creek and Fort St. John. In addition to the consortium monitoring stations, the consortium researchers have access to seismicity data from stations operated by a number of other entities, including NRCan, the University of Calgary, and Symroc Business and Project Management Ltd.
What was found?
As the network has expanded across the Liard Basin, Horn River Basin and Montney play, the determination of earthquake epicentres and magnitude resolution in Northeast BC has greatly improved. The magnitude of completeness for the Northern Montney seismicity monitoring area (NM) was ~1.3 and was ~1.0 for the Kiskatinaw Seismic Monitoring and Mitigation Area (KSMMA). The majority of induced seismicity in northeast BC occurs within these two areas. All events registered by the network are published on the NRCan website here.
In 2021 the earthquake detection system was enhanced using the GrowClust program (Visser et al., 2021, Trugman et al., 2017) to improve earthquake location accuracy relative to each other, allowing for the identification of features of interest. This has revealed that many events in the region occur along NE-SW trending linear patterns. The mapping of these lineations may prove useful in helping to mitigate seismic risk of potential well completion or disposal operations associated with geological features along those trends.
Another 2021 enhancement was the ability to spatiotemporally attribute seismicity to nearby HF and WD operations. This has allowed the study of why some wells trigger events in greater numbers than others. One key observation from this analysis has shown that wells targeting the Lower Middle Montney induce more seismicity than those targeting other members of the Montney Formation. Additional analysis on influential factors also found that HF operations played a more significant role than WD operations in the monitored area.
The report used lineations which is not the most technical word in the world but I felt like this was a bit more lay-speak. Agree? Or should we just keep as lineations (which I have used in the next line)?