SEGJ Technical Conference

Numerical Simulation of Reciprocity for Transition-Zone Survey and Reverse-Time Redatuming

Abstract We used the finite-difference method to compute full wavefields to investigate combinations of source and receiver types and thus determine which combination is best for acquisition of transition-zone seismic data. First, we compared the synthetic time series recorded by an onshore geophone from an offshore airgun source with that recorded by an offshore hydrophone from an onshore vibrator source. Then, we compared the synthetic time series recorded by an onshore geophone from an offshore airgun source with that recorded by an offshore hydrophone from an onshore dynamite source. For both cases we found perfect agreement of the waveforms. For the onshore dynamite source, multicomponent geophones distributed in a wide array are needed to derive dilatancy. When onshore geophones are used at the surface, geometric symmetry is not obtained because the offshore streamer is towed a little below sea level and the dynamite source is fired a little below surface level. Accurate subsurface waveforms can be reconstructed from surface records by applying the reverse-time FD method.