P-S seismic exploration: A mid-term overview
Robert R. Stewart, Donald C. Lawton
Three-component (3-C) seismic recording captures the seismic wavefield more completely than conventional techniques. It is thus useful for enhancing conventional P-wave imaging as well as for generating S-wave images. In the last several years, 3-C surveying has developed rapidly - often to create converted-wave (P-S) images. Largely conventional survey design and acquisition can be used for P-S recording.Some special processes for P-S analysis include anisotropic rotations, shear receiver statics, asymmetric binning, shifted hyperbolic velocity analysis, P-S to P-P transformation, P-S DMO, pre- and post-stack migration, and stacking velocity and reflectivity inversion for S velocities. Current P-S sections are approaching the quality of conventional P-P seismic data. Numerous applications for P-S sections have arisen including sand/shale differentiation, limestone/anhydrite/dolomite identification,definition of interfaces with low P-wave contrast, anisotropy analysis, imaging through gas zones, and reservoir monitoring. Converted-wave analysis holds great promise for marine surveys and land 3-D problems. Imaging through volcanic (or high-velocity) layers and in regions of significant structure also look promising. Development of the P-S method has taken about 10 years, but is now entering into its commercial phase and promises considerable usefulness.