CRS Tutorial
Introduction
The CRS workflow is a powerful tool for a stable and quick processing chain from time to depth imaging. It relies on a hyperbolic second order approximation of the reflection response. Currently it consists of the CRS stack, the NIP-wave tomography, prestack data enhancement tools and initial approaches to address surface related multiples. We combine all these tools to a complete workflow to obtain an integrated processing approach based on CRS stacking parameters. Exemplary results from the processing of real data sets are presented.
Illustration of the CRS wokflow
CMP vs. CRS stack
2D stack results. Left: conventional CMP stack, Right: CRS stack for low-fold land data from Northern Germany.
Prestack data enhancement: Partial CRS stack
Low-fold land data from Northern Germany. Left: CMP gather with about 20 traces distributed irregularly. No coherent reflection events can be observed. Right: Partially stacked CRS supergather provides regularised traces with increased S/N ratio and enhanced continuity of reflections.
Multiple suppression technique
Marine data. Top: Stack section with multiples. Multiples masking primary events, especially between 1.0 s and 1.2 s at CMP location 1200. Buttom: Stacked section after applying the proposed approach. Multiple energy could be successfully removed and previously hidden primary energy becomes visible.
PreSDM
CIGs of low-fold land data from Northern Germany. Migration velocity model was obtained using NIP-wave tomography. Left: Conventional CIG. Right: CIG obtained from depth migrated CRS supergathers.
Prestack depth migrated sections
PreSDM of low-fold land data from Northern Germany. Migration velocity model was obtained using NIP-wave tomography. Top: Conventional PreSDM. Buttom: PreSDM section of CRS supergathers. The areas of improvement are shown with the black arrows.