LAUSR

Multimode and multicomponent elastic Gaussian-beam migration is attractive for its efficiency, flexibility, and accuracy. However, when it is used for ocean-bottom seismic data, the incomplete boundary condition will yield some nonphysical artifacts in the final migrated images. To solve this problem, we extend the elastic Gaussian-beam migration method from 3C to 4C by introducing the pressure recording to represent the stress tensor on the ocean bottom. Based on the elastic wave equation and the complete boundary condition for the ocean-bottom model, we derive effective formulas of accurate multimode wave downward continuation. With our method, different wave modes are separated and the receiver ghost is removed simultaneously by applying a decomposition matrix to 4C data during the migration without prior data separation and deghosting, which eliminates the artifacts better and reduces the processing cost. Three synthetic experiments were provided to validate the method for 4C ocean-bottom data migration.