Sometimes the earth strata lie horizontally with little irregularity.
There we may hope to ignore the effects of migration.
Seismic rays should fit a simple model with large reflection
angles occurring at wide offsets.
Such data should be ideal for the measurement of reflection
coefficient as a function of angle,
or for the measurement of the earth acoustic absorptivity 1/Q.
In his doctoral dissertation, Einar
reported such a study.
The results were so instructive that the study will be thoroughly reviewed here.
I don't know to what extent the Grand Isle gas field typifies
the rest of the earth,
but it is an excellent place to begin learning about the
meaning of shot-geophone offset.