Optimum bin size for converted-wave 3-D asymptotic mapping

Donald C. Lawton

A program has been developed to generate fold maps for converted waves recorded in multicomponent 3-D seismic surveys. The asymptotic conversion point is assumed for computing subsurface multiplicity. When a conventional common-midpoint bin size of half the receiver interval (Ar/2) is used, the fold distribution is highly variable and empty rows of bins parallel to the shot lines may result for the case when Vp/Vs = 2 and the shot line spacing is an even integer multiple of r. Overlapping adjacent bins removes the empty bin problem but does not necessarily result in a smooth fold distribution. The optimum bin size for 3-D converted wave data is r/(1 + Vs/Vp). Asymptotic binning using this bin dimension was found to produce a smooth fold distribution which is relatively insensitive to Vp/Vs.