Considerations in 3D depth-specific P-S survey design

Donald C. Lawton, Peter W. Cary

A new sparse-shot design for 3D P-S surveys is introduced. In the sparse shot design a shot separation greater than the receiver separation is used, and given by the relationship s = r(1 + Vp/Vs)/2. This design yields fewer non-unique P-S traces than traditional 3D surveys with equal source and receiver intervals. New measures of global offset and azimuth distribution quality are developed which are tested in several design examples. These measures show that orthogonal and slant designs for P-S surveys yield similar design quality measures. An OBC survey example is also used to illustrate the efficacy of the sparse-shot design.