Waveform modelling of deep reflections from complex strata at Tariki, New Zealand, using an F- K domain propagator method

Abstract

The probable reasons for the poor quality of seismic data in a complex situation are resolved by performing tests which use a recently developed method for modelling acoustic wave propagation in laterally heterogeneous media. Features of the example include ragged topography, steeply dipping strata and a surface layer of swamp of variable thickness. The method used is a variant of the classical propagator method which is modified to avoid the usual inherent numerical instability. Synthetic seismic sections, each composed of 64 shot gathers, are generated. In these sections waves not reflected from the region of the deep strata of interest have been removed. The advantage of this is that only low wavenumbers need be considered. In addition, changes can be made to part of the medium without having to repeat all the calculations. The results obtained without the swamp layer reproduce almost the exact form of the subsurface structure, whereas allowing for the swamp results in a poorly defined image characteristic of observed seismic sections.