Dip limitations on migrated sections as a function of line length and recording time

The length of a seismic profile and the recording time available as input to migration govern simple equations relating dip observable on migrated profiles to the spatial location of the reflector. This relationship is important to exploration geophysicists seeking critical seismic dip and to deep crustal geophysicists examining the nature of the continental crust. A certain amount of the observed decrease of dip with depth, and the dip biasing on the edges of migrated sections, can be related to the size of the input, as shown in a real data example. Any further decrease in dip with depth may have geologic significance. To portray (image) up to 45‐degree dips at the target depth, 50 percent more time must be recorded and input to the migration as the two‐way migrated time of the target. The lead‐in (or step‐in) required on both ends of the line is the depth to the target. For 0‐ to 30‐degree dips to be present at the target depth, one‐sixth more time must be recorded and input to the migration; the lead‐...