When dealing with real data we almost never know what the true velocity of
the subsurface is. Therefore it is important to understand the effects of
velocity on our angle-gather time migration algorithm. To do this we
simply created data for the dome model in Figure 4 at a
fairly high velocity (3 km/s) and migrated it using a low velocity (1.5 km/s).
The results are in Figure 11. For angles less
than the maximum useful angle (
), the angle-domain gather
behaves exactly as the offset-domain gather does. Beyond the maximum
useful angle, the events become even more curved and the amplitudes begin
to change.
The behavior of the angle-gather migration is very similar to that of offset-domain migration as long as the limitation of the maximum useful angle is recognized. Therefore, we can probably expect angle-gather migration to behave like offset-domain migration in v(z) media also.
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