New developments in 3C-3D survey design for converted waves are shown, using the Blackfoot 3C-3D survey design as an example. The initial Blackfoot design showed high frequency P-S fold variations when a bin-centred P-P reflection point acquisition geometry design was used. Asymptotic P-S fold is smoother when a bin fractionation design is followed. In this case, the Flexi-bin® approach was used to assist in the design of the final survey. The survey consists of 1395 sourcepoints and 903 receivers, recorded in 2 fixed patches with up to 700 receivers per patch. The survey hence can be considered as two, overlapping subsurveys with a number of shots common to both patches. Depth-variant fold mapping capabilities have been developed which show that the actual fold distribution at target horizons will vary significantly with the choice of Vp/Vs.
View full article as PDF (41.43 Mb)