Frequency-domain elastic full waveform inversion of synthetic time-lapse geophysical monitoring data for Korean offshore CCS project

Abstract

For successful commercial CCS (Carbon Capture and Storage) projects, monitoring the migration of subsurface CO2 plume is important. Among the various geophysical monitoring methods, the time-lapse seismic monitoring is one of the most promising methods due to the high resolution of seismic survey. To monitor the injected CO2 plume accurately, it is needed to interpret the monitoring data using the full waveform inversion, because subsurface material properties can be estimated through the inversion. In addition, unlike the imaging technique, we can estimate the amount of CO2 plume underground using the full waveform inversion. Although the time-lapse seismic monitoring has been widely studied in the CO2 storage sites abroad, the interpretation of monitoring data is mainly based on the imaging technique such as the reverse time migration. In this study, for the near-future commercial CCS projects in Korea, we perform the frequency- domain elastic full waveform inversion for a synthetic geological model made after Ulleung Basin, which is one of the CO2 storage site in prospect in Korea. We suppose that the target of the CO2 injection is located in the structurally-undeformed area of the southwestern continental margin of Ulleung Basin (see the potential siteⅡ in Shinn et al. [2012]). We also suppose that the CO2 plume migrates through the injection layer and is confined by the stratimising methods due to the high resolution of seismic survey. To monitor the injected CO2 plume accurately, it is needed to interpret the monitoring data using the full waveform inversion, because subsurface material properties can be estimated through the inversion. In addition, unlike the imaging technique, we can estimate the amount of CO2 plume underground using the full waveform inversion. Although the time-lapse seismic monitoring has been widely studied in the CO2 storage sites abroad, the interpretation of monitoring data is mainly