Elastic 3D PS converted-wave Gaussian beam migration

Elastic wave migration is a desirable technique because it can image the structure of the earth more accurately. We develop a new elastic Gaussian beam migration method with 3D three component (3D-3C) seismic data that focuses on a complex PS-converted wave. Based on the elastic wave equations and complete boundary conditions, we have derived effective work formulas for an accurate multimode wave downward continuation for the free-space, ocean-bottom and free-surface models. We separate PS wave into linear-polarized P-S1 and P-S2 waves to simplify the expression and derivation of the migration. To image vectorial wave directly and solve the reverse polarity issue, we use the cross-correlations of P wave divergence and PS wave curl operators as the 3D P and PS imaging conditions, and introduce a unit vector to define the rotation direction of PS wave. With our approach, the 3D-3C multimode waves are automatically decomposed to P and PS waves during the migration, and without the need for prior data separat...