REVERSE-TIME MIGRATION

Elastic prestack, reverse-time depth migration is applied to both synthetic data and four-component eld data from the Valhall area. Reverse-time extrapolation of the recorded multi-component data is by 2-D elastic nite di erence solution to the full wave equation. An eikonal solver is used to compute the acoustic traveltime from the source to the image points. By using horizontal inline and vertical particle velocity components, the converted P-to-S re ections are imaged simultaneously with the primary P-wave re ections, shot by shot. Synthetic results showed that the elastic reverse-time migration gave better images of the subsurface structure than traditional Kirchho -like migration. Preliminary eld data results show the feasibility to image the earth structure using the reverse-time migration.