Seismic depth processing using the CRS technique - a 3D land data example from Mexico

A case study for 3D land data from Mexico shows that high-resolution image and attribute volumes from CRS time processing directly add to a fast and accurate depth model building and imaging. A superior initial depth model that reproduces the subsurface dip without require continuous horizons is provided by CRS tomographic inversion. In alternative model building approaches, however, the lack of horizon continuity in low-fold areas is the major draw-back for layer-based model building, whereas the structural dip is not honoured by vertical Dix inversion of stacking velocities. The smooth CRS tomography model is well suited for an initial PostSDM of the CRS stack, which exhibits an excellent subsurface resolution in comparison to prestack time migration. The first phase of CRS-based depth processing comprising CRS Tomography and CRS PostSDM, thus provides an increase of subsurface resolution from time processing results at little additional effort. The second phase gains additional accuracy by the costly steps of model update, and PreSDM. In order to improve the image in areas with salt intrusions, the salt bodies are interpreted in the CRS PostSDM result, and inserted into the CRS tomography model. Further runs of PreSDM and model updates complete this depth imaging phase.