How can passive seismic imaging techniques be used to monitor temporal variations in structures at CO2 sequestration sites?

Meeting the global challenge of reducing greenhouse gases requires safe and effective CO2 sequestration. A critical component of CO2 sequestration, and its containment, is timely monitoring structural changes that result from stresses introduced by CO2 injection to prevent or mitigate failures. Established monitoring strategies utilize detailed controlled source 3D seismic surveys to image small-scale structures around injection sites. However, a drawback of this approach is its need for signals produced by man-made seismic sources, such that subsurface structures are only periodically captured when sources are generated. The temporal development of structural changes and a broader geologic context surrounding the injection sites are often left unresolved. An alternative to controlled source seismic surveys is passive seismic (PS) imaging, which utilizes signals from earthquakes or other cultural or industrial sources. PS imaging is ideally suited for continuous monitoring, as demonstrated by its successes understanding induced earthquakes near dams (e.g., Brazeau River, Alberta) and wastewater (near Rocky Mountain House, Alberta) or hydraulic fracturing (Fox Creek, Alberta) operations. PS imaging has also successfully monitored CO2 injection sites (e.g., near Weyburn, Saskatchewan), but its scope (and application) in Alberta remains in its infancy. The collaborative project outlined here will overcome this limitation and aims to answer the Big Question: How can passive seismic imaging techniques be used to monitor temporal variations in structures at CO2 sequestration sites? Expected outcomes from this study address the Grand Challenge #6 of capturing CO2, within GRI Theme #3 of CO2 conversion. And UA Theme #2 of Future energy systems related to carbon capture, utilization and storage.