Application of acoustic anisotropic time-lapse full-waveform inversion at the Sleipner field

The Sleipner project is the first commercial-scale offshore carbon capture and storage (CCS) project in which time-lapse seismic surveys were successfully applied to monitor the injected CO2 plume. Because seismic anisotropy in the sedimentary basins can influence the multi-channel seismic data, a proper anisotropic time-lapse seismic imaging technique is required to consider anisotropy to precisely estimate the injected CO2 plume. In this study, we perform acoustic multi-parameter full-waveform inversion (FWI) based on the elliptical anisotropy to increase the accuracy of time-lapse seismic monitoring results at the Sleipner field. We first build an initial anisotropic velocity model using the Backus averaging. Then, we compare the accuracy of velocity models from the anisotropic FWI with those from the isotropic FWI. As a result, we confirm that anisotropic time-lapse FWI improves the monitoring result, in which the anisotropic parameter corrects kinematic information and acts as a garbage collector in multi-parameter FWI.