Finite-difference modelling for the optimisation of coherent-noise suppression in very shallow seismic reflection

Abstract

Seismic reflection surveys with targets at depths of 0-100m have been widely reported in the published literature. There are many case studies and theoretical discussions of methodology and technique. However, there exist no significant modelling studies of shallow seismic methodology. In this study we have used viscoelastic finite-difference modelling to generate shot records that can be processed using a real world sequence. This approach has allowed investigation of a range of problematic issues relating to very-shallow reflection. Perhaps the most fundamental shallow-reflection problem relates to the extraction of signal from beneath coherent noise. Our modelling provides a clear demonstration of the stringent acquisition parameters that are needed if this noise is to be removed using conventional f-k domain processing tools. Concepts investigated in the modelling are further explored via an engineering scale hammer seismic survey, which successfully images reflectors in the range 0-50m, using both pre-critical and post-critical reflections.