After deciding on the migration strategy and the appropriate algorithm, the analyst then needs to decide on the migration parameters. Migration aperture width is the critical parameter in Kirchhoff migration. A small aperture causes removal of steep dips; it generates spurious horizontal events and organizes the random noise uncorrelated from trace to trace.
Depth step size in downward continuation is the critical parameter in finite-difference methods. An optimum depth step size is the largest depth step with the minimum tolerable phase errors. It depends on temporal and spatial samplings, dip, velocity, and frequency. It also depends on the type of differencing scheme used in the algorithm.
Finally, the stretch factor is the critical parameter for Stolt migration. A constant-velocity medium implies a stretch factor of 1. In general, the larger the vertical velocity gradient, the smaller the stretch factor needs to be.
- Exploding reflectors
- Migration strategies
- Migration algorithms
- Aspects of input data
- Migration velocities