Velocity analysis using prestack depth migration: applying the linear theory
, by John T. Etgen
The linear theory I presented in the previous SEP report can be used to predict the effect
a change in the interval-slowness model has on prestack depth-migrated constant-offset
sections. The effect we can detect are changes in the curvature of the images of reflectors
along their normals. An example shows that the linear theory can predict the change in
curvature over offset and pull-up or push-down of a reflector due to a local anomaly
interval slowness above the reflector. A generalized inverse of the linear operator applied
to measured changes in residual curvature can be used to estimate the slowness anomalies
above the reflector. I plan to use the linear theory to drive an iterative nonlinear
inversion that estimates interval slowness models to use for prestack depth migration.
STANFORD