Seismic imaging: Data processing
Seismic reflection processing was performed using PC-based software and, for the most part, followed standard processing protocols. Because of the severe shallow distortions, we applied our own routines for static (time) correction analysis and modeling (operations 3, 4 and 8 in table 2, for further information see Pugin and Pullan, (2000)). This near-surface correction process involves a very careful measurement of the initial arrival of the seismic signal (the first break) at each of the 48 channels recorded after each of the 10,250 impacts. The time shift, which is mainly a result of variations in the thickness of the unconsolidated sediment, severely affects the quality of the stacked seismic section. Figure 3 shows how removal of these time shifts through the alignment process tremendously increases the quality of the section. The section displayed in Figure 3 shows an anticlinal feature with fractures on its left edge. The large amplitude observed in the envelope attribute section and the repeated or "multiple" energy present below the strong reflection implies that this anticline or dome may contain methane.