I am very lucky to have been able to continue my collaboration with the Containment and Monitoring Institute (CaMI), a business unit of CMC Research Institutes in Calgary thanks to the UKCCSRC ECR Collaboration Fund. I have had broadband seismometers deployed at CaMI’s Field Research Station (FRS) near Brooks, Alberta since 2015, thanks to ECR grants from the UKCCSRC. The project aims to simulate a leak from a CO2 storage site to allow the full range of monitoring technologies to be tested for their ability to detect CO2 in the shallow subsurface. The injection of CO2 at a depth of 300m began in 2018 and to date 17 tonnes have been injected. Geophysical, geochemical, geomechanical and geodetic monitoring research at the site will be used to study the subsurface gas plume to improve understanding of shallow groundwater systems, fluid flow and the behaviour of CO2 in an aquifer.
The aim of my project to deploy broadband seismometers at the FRS is to determine whether small seismic events with magnitudes < 0, termed microseismicity, are caused by shallow CO2 injection in subsurface. Additionally, the sparse array of seismometers continuously record the ambient noise field and cross-correlation of these recordings can be used to estimate seismic velocities between the stations. An assessment of the change in velocities over time can be used to indicate the presence of CO2.
My visit to Canada in May began with a visit to the FRS to download the data from the seismometers that had been recorded in the preceding 6 months. This time in the field I was accompanied by Ophelia George, University of Bristol Geophysics Group’s geophysics technician (see photo). As you can see from the photo we were accompanied by Brunel Duck, the Geophysics Group mascot. He’s become quite attached to his visits to Brooks. If you’re ever in town he recommends Montana’s for food and beer. Also, after 8 visits to the FRS site, I can confirm it is always sunny and warm when you want to work! (Although, one day we were chased out of the field by a thunder storm).
The second part of my visit I spent at CaMI’s office on the University of Calgary campus working with Marie Macquet, a postdoc with Don Lawton, Director of CaMI. The aim of the visit was to combine our datasets to produce an assessment of the stability of the seismic velocities we can measure using ambient noise recording. Her data comes from >90 geophones deployed at the site. In addition to our work I also learnt about the work being done by the CREWES group, an industry funded applied geophysical research group at the University of Calgary, walked by the beautiful Bow River and gratefully ate home cooked food at Marie’s house. By the end of my visit we had made good progress by ironing out the difficulties with combining different datasets and obtained preliminary results.
In August, my second visit coincided with the CMC Research Institutes Subscriber Workshop and the IEAGHG Monitoring and Environmental Research Combined Networks Meeting. At these meetings Marie and I presented our initial results from our joint work on ambient noise interferometry (see photo). CaMI also organised a field trip to the FRS site for meeting attendees where Marie and I showed our seismic monitoring equipment and described our work to other academics and industry representatives. It was an excellent opportunity to meet a wide range of people with a broad range of expertise in environmental and geosciences monitoring.
Our broadband seismometers remain at the FRS where further CO2 injection is planned for the autumn in larger quantities. Our collaboration with CaMI and the University of Calgary is ongoing – look out for publication of the results!