Source signature and static shifts estimations for multi-component ocean bottom data

Correction using maximum pulse alignment

One way to calculate the static shifts correction is by aligning the maximum pulse of the source signature. A typical air-gun signature, including the effect of the source ghost, consists of a large pulse and its bubbles, as shown in Figure 4. Since the amplitude of the initial maximum pulse is much higher than the amplitude of the bubble, we can estimate the static correction by picking and aligning the time of the maximum pulse. The middle panel of figure 5 shows the z-component of the resulting direct-arrival after static shifts correction using this method.

exshot
Figure 4. A typical air-gun signature consists of a large pulse and its bubbles. The negative signal comes from the source ghost. [NR]

Flat
Figure 5. (Top) Vertical velocity before static shifts. (Middle) Vertical velocity after static shifts correction using maximum pulse alignment. (Bottom) Vertical velocity after static shifts correction using cross-correlation. [ER]

Searching for the maximum pulse can be tricky for traces at large offset, as the amplitude of the pulse attenuates with a longer travel distance. Satisfactory results can be obtained up to an absolute offset of $\pm 5000m$. We have restricted the search neighborhood to be near the LMO time in order to alleviate this problem. The top panel of figure 6 shows the static shift calculated at different offsets by aligning the maximum pulse.

Source signature and static shifts estimations for multi-component ocean bottom data