Can towed-streamer seismic data be used for elastic wave imaging? Synthetic and field data examples

In marine seismic exploration, towed-streamer seismic data acquisition stands out as a prevalent and economical approach. This data records scalar pressure and captures P waves including those that are converted from sub-seabed S waves. Theoretically, towed-streamer seismic data can be used to reconstruct S-wave fields for elastic wave imaging via backward extrapolation. Our research applies an acoustic-elastic coupled equation that includes a pressure term to perform elastic reverse time migration, using the pressure seismic data as the boundary condition for backward extrapolation. The feasibility of employing towed-streamer seismic data for elastic wave imaging of complex subsurface structures is confirmed through synthetic and field data examples. The investigation demonstrates how the smoothness of velocity and density models impacts the quality of elastic reverse time migration using towed-streamer seismic data. We find that using smooth velocity and density models for elastic wave imaging can enhance imaging quality by utilizing transmitted S waves. Furthermore, certain nonphysical S waves generated during backward extrapolation can contribute to PS images, as evidenced by a synthetic data example. Overall, the results indicate that the towed-streamer seismic data for elastic wave imaging has potential in marine seismic exploration. Moving forward, it is crucial to focus on refining the quality of PS images and reducing artifacts caused by the backward extrapolated nonphysical waves.