4D synthetic time-lapse FWI experiments for CO₂ monitoring configured for the Snowflake dataset

Jinji Li, Kimberly Pike, Kristopher A. Innanen, Kevin W. Hall

Time-lapse full waveform inversion (FWI) is essential for energy transition efforts, particularly in monitoring CO₂ geo-storage. As part of the Containment and Monitoring Institute (CaMI) Field Research Station (FRS) project by Carbon Management Canada (CMC), this study aims to validate 4D seismic monitoring for Carbon Capture and Storage (CCS). In this study, we conduct synthetic tests for 4D acoustic FWI monitoring based on the Snowflake survey concepts, which include both walk-away and walk-around Vertical Seismic Profile (VSP) acquisitions. We begin by presenting a revisited well log from CaMI, followed by the synthetic models employed in our analysis. We carry out baseline FWI using a comprehensive source acquisition strategy. Subsequently, we conduct a series of monitoring tests utilizing different source acquisition methods, time-lapse inversion strategies, and varying sizes of P-wave velocity changes resulting from CO₂ injection. Our findings suggest that full source coverage may not be necessary for effectively tracking CO₂ plume migrations. Additionally, our comparison of sequential and parallel strategies in time-lapse FWI indicates that the parallel approach is likely more robust and effective. Finally, we note that due to the limited resolution of FWI, smaller-scale plume migrations may not be adequately detected. Overall, this study provides insights into optimizing source acquisitions to minimize environmental impact while ensuring efficient detection of CO₂ migration.