Direct measurement of frequency dependent phase velocity and seismic attenuation from the Snowflake dataset

Chioma Chineke

Carbon Capture and Storage (CCS) stands out as an effective technique for mitigating the CO₂ footprint in the atmosphere. Ensuring the containment of sequestrated CO2 within geological storage is crucial, necessitating continuous monitoring. The research presented here leverages data from the Newell County facility, a shallow CO₂ injection project actively promoting advancements in measurement, monitoring, and verification technologies related to CCS. The seismic method proves valuable for estimating frequency-dependent phase velocities of seismic waves. The concept of dispersion reveals that seismic waves of varying frequencies travel with distinct velocities, primarily due to non-uniform elastic properties in the subsurface, leading to frequency-dependent attenuation. As a preliminary step in estimating frequencydependent seismic attenuation, this study aims to estimate the frequency-dependent phase velocities of the seismic waves as they propagate through the earth. The chosen method involves the analysis of uncorrelated vibroseis data, with a specific emphasis on the frequency dependence of seismic velocities. The estimated phase velocities were further utilized in predicting Q using the Kolsky dispersion model. The lateral and VSP azimuth changes in the phase velocity and seismic attenuation reflect the spatial heterogeneity in the near surface.