Ambient noise correlation study at the CaMI Field Research Station, Newell County, Alberta, Canada

Marie Macquet, Donald C. Lawton

We recorded passive continuous seismic data at the CaMI Field Research Station to study the feasibility of using ambient noise correlation method as an additional tool to monitor and verify secure storage of the injected CO₂ . In this paper, we focus on two aspects: (1) the near surface tomography, using 112 stations along the 1.1 km trench and (2) the long-term monitoring of the velocity change using continuous recording since October 2014 on 7 broadband stations. Due to the frequency range of the geophones used for the tomography part, the investigation depth remains shallow (up to 50 m depth). Nevertheless, a good near-surface velocity model remains important for active seismic processing. The VS model obtained with ambient noise correlation method is similar to the one obtained from an active shear seismic source study (bedrock depth and VS range).

Concerning the monitoring using the ambient noise correlation method, the daily correlations between 2 broadband stations show good coherency. The velocity variation between the daily correlations and the reference are obtained using Moving Window Cross Spectrum analysis on the daily correlations. The effect of the seasonal temperature is clearly visible on the velocity variation curves. We also suspect an effect of the CO₂ injection. Further analysis is required to confirm the first observations.