Stack-power maximization in practice
The method of stack-power maximization can yield better stack compared to the method of traveltime decomposition in areas with poor signal-to-noise ratio. Figure 3.3-44 shows a CMP-stacked section along a land profile with field statics corrections applied (Figure 3.3-45). While the left-half of the section has a good signal-to-noise ratio, the right-half has a poor signal-to-noise ratio resulting from irregular topography and near-surface complexity (Figure 3.3-45). Note, for instance, the loss of continuity along the reflection events at 0.8 and 1.3 s at the right-half of the section.
Selected CMP gathers shown in Figure 3.3-46 verify the presence of short-wavelength statics. Following residual statics corrections by stack-power maximization and the subsequent velocity analysis, the same gathers indicate that short-wavelength statics have been largely resolved (Figure 3.3-46), and thus, the resulting CMP stack shows significant improvement in the continuity of reflections in the right-hand side (Figure 3.3-47). The shot and receiver residual static shifts derived by using the supertrace scheme described above are shown in Figure 3.3-48. Note that mainly large residuals are in the right-half of the profile with irregular topography.
Figure 3.3-44 A CMP-stacked section with field statics corrections (Figure 3.3-45).
Figure 3.3-46 Selected moveout-corrected CMP gathers before (top) and after (bottom) residual statics corrections. The gathers on top are associated with the CMP stack shown in Figure 3.3-44, and the gathers shown at the bottom are associated with the CMP stack shown in Figure 3.3-47.
Figure 3.3-47 The CMP-stacked section as in Figure 3.3-44 with residual statics corrections (Figure 3.3-48).
- Residual statics estimation by traveltime decomposition
- Residual statics estimation by stack-power maximization
- Traveltime decomposition in practice
- Maximum allowable shift
- Correlation window
- Other considerations
- Topics in moveout and statics corrections