Browsing by Author "Kolkman-Quinn, Brendan James"

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    Time-lapse VSP monitoring of CO2 sequestration at the CaMI Field Research Station
    (2022-04-07) Kolkman-Quinn, Brendan James; Lawton, Donald Caleb; Innanen, Kris; Dettmer, Jan
    The Containment and Monitoring Institute Field Research Station (CaMI.FRS) is a carbon sequestration field experiment near Brooks, Alberta. CO2 is injected into a saline aquifer in the 6 m thick, 10% porosity Basal Belly River Sandstone at 300 m depth. This CO2 plume simulates a shallow leak scenario from an industrial scale CO2 storage reservoir. Vertical Seismic Profiles (VSP) were collected between 2017 and 2021 to determine a detection threshold and delineate the plume. These data had high repeatability, with permanent borehole sensors and identical source coordinates. Seasonal variations in surface and near-surface conditions were the main source of dissimilarity between baseline and monitor data. A time-lapse compliant processing workflow was developed for the 10 Hz – 150 Hz shallow data. This workflow produced directly comparable amplitudes between baseline and monitor data, except at higher frequency bands affected by variable near-surface filtering. Spectral differences were eliminated with high-cut filters designed for each source location. Avoiding the use of shaping filters preserved the subtle amplitude response of the CO2 plume in the remaining bandwidth. After 33 t of injection, the CO2 plume produced an observable time-lapse amplitude anomaly on multiple geophone datasets on two monitoring lines. The interpreted CO2 plume matched forward modeling expectations of approximately 50 m lateral extent, but with an asymmetric distribution around the injection well. Equivalent DAS datasets possessed lower signal strength than geophone data, with instrument noise interfering with the CO2 amplitude response. A weak seismic anomaly was observed on only one DAS monitoring line. The high-confidence geophone results establish a leak detection threshold at 33 t of CO2 for this geological setting. The ability to detect a 33 t CO2 plume with VSP field data lends confidence to Measurement, Monitoring, and Verification capabilities at industrial operations with injection rates of kilotonnes or megatonnes per year. The time-lapse compliant VSP workflow will help inform shallow monitoring procedures, while the CO2 delineation will contribute to future multi-disciplinary studies at CaMI.FRS.