The reef program generates a velocity data file for the seismic and revtime programs. Reef structures are characterized by reasonably flat layers which change abruptly laterally. The reef section is usually narrow in one dimension and long in the other dimension. Reefs like this model can be found in the Alberta province of Canada. The reflections change across the reef in amplitude, and reflections from layers below show time push down or pull ups depending on the lateral velocity differences. If the velocity in the reef is higher than in adjacent sections, then the times from the reflections from the bottom of this layer will pull up over the reef section. The velocities of this model have maximum to minimum ratio of 3. A portion of the reef.f program listing is shown in PROGRAM CODE III.
PROGRAM CODE III, a portion of reef.f --- View code