Multiconverted Reflections in Marine Environments with Thin Permafrost Layers
In the Canadian Beaufort Sea, high-quality conventional P-wave reflection seismic data are difficult to obtain because of a severe screening effect of a shallow layer of ice-bearing permafrost. Multiconverted reflections (PSPPSP) were studied in this thesis project in order to evaluate images of reflections underlying a high-velocity layer. Acoustic seismic physical modeling and numerical modeling experiments were undertaken for multiconverted reflection (PSPPSP) recognition and analysis. Both the physical and numerical modeling results indicate that values of the S-wave velocity in the high-velocity layer and of the P-wave velocity in deeper layers are the most important quantities affecting the multiconverted PSPPSP reflection amplitude. Based on these investigations, two lines of field data (datasets A and B) from the Canadian Beaufort Sea were processed. From this field data study, it was concluded that analysis of the multiconverted reflections is very critical for the data interpretation in this environment, especially for the shallow section.