Application of the ray-reflectivity method to multilayered thin bed structures

Abstract

Abstract The high degree of efficiency of the latest version of the ray-reflectivity technique (Daley and Hron, 1990) and its suitability for detailed studies of the seismic response of thinly laminated structures are demonstrated by computing SH synthetic traces for a simplified 45-layer coal seam sequence from the Ruhr valley district in western Germany. Unlike the previous paper, which concentrated on the special features of critically refracted waves propagating along a thin high velocity layer, this paper investigates numerical aspects of the computation of the reflected field for a precritical range of offsets. We emphasize that the numerical efficiency of the computer program is due mainly to automatic ray generation algorithms employing the concepts of kinematic and dynamic analogs. The main advantage of this technique, namely its capability for the automatic interpretation of individual events seen on the computed traces in terms of ray paths in the thick layers, has been employed for the positive identification of multiple reflections from the stacks of thin layers in the deeper part of the model. Our computer code, which in the current version allows for up to 100 thin layers interspersed among 10 thick layers, is suitable for the numerical modeling of the seismic response from thinly laminated models obtained from acoustic log data routinely measured in seismic prospecting for hydrocarbon deposits.