The influence of the Goos–Hänchen effect on seismic data processing and AVO in attenuating media

Abstract

The Goos–Hänchen (GH) effect induced by the total reflection of an incident beam of P-wave from a low-impedance medium to a high-impedance medium at near- and post-critical angles was theoretically simulated and discussed. For both PP- and PSV-waves, there may be large GH shifts (GHS) and penetration depths (PD) for both lossless and attenuating media. As the Q-factor increases, or the frequency of the seismic wave decreases, the GH effect is increased. However, in attenuating media, there may be non-zero GHS and PD at all non-zero incident angles, not just post-critical angles. GHS may be either positive or negative, while PD is positive only. Compared to the Q-factor in the incident medium, the Q-factor in the transmission medium may play a more dominant role in the determination of reflection coefficients, GHS, and PD. The GH-induced normal moveout (NMO) discrepancy of the PSV-wave may be larger than that of the PP-wave. Due to the GH effect, there may be an angle discrepancy (at fixed offset) between the GH-modified incident angle and the traditional incident angle. In addition, the GH effect at a given offset may produce two or three reflected waves, from different incident angles. These results suggest that, within their assumptions, the GH effect may lead to errors in NMO estimates and the vertical location of the reflector. Furthermore, there may be errors in offsets, incident angles, and reflection amplitudes, in the analyses of the amplitude variation with offset (AVO). These GH effects might be more important for seismic data at fixed offsets and shallow layers, and for sonic log data, which might fall into the post-critical angle regime. Therefore, there may be a necessity to take into account the GH effect in the interpretation of wide-angle reflection data in NMO and AVO analyses.