Efficient ray tracing algorithms based on wavefront construction and model based interpolation method

摘要

Understanding and modeling seismic wave propagation is important in regional andexploration seismology. Ray tracing is a powerful and popular method for this purpose.Wavefront construction (WFC) method handles wavefronts instead of individualrays, thereby controlling proper ray density on the wavefront. By adaptively controllingrays over a wavefront, it efficiently models wave propagation. Algorithms for aquasi-P wave wavefront construction method and a new coordinate system used togenerate wavefront construction mesh are proposed and tested for numerical propertiesand modeling capabilities. Traveltimes, amplitudes, and other parameters, whichcan be used for seismic imaging such as migrations and synthetic seismograms, arecomputed from the wavefront construction method. Modeling with wavefront constructioncode is applied to anisotropic media as well as isotropic media. Syntheticseismograms are computed using the wavefront construction method as a new wayof generating synthetics. To incorporate layered velocity models, the model basedinterpolation (MBI) ray tracing method, which is designed to take advantage of thewavefront construction method as well as conventional ray tracing methods, is proposedand experimental codes are developed for it. Many wavefront constructioncodes are limited to smoothed velocity models for handling complicated problemsin layered velocity models and the conventional ray tracing methods suffer from theinability to control ray density during wave propagation. By interpolating the wavefrontnear model boundaries, it is possible to handle the layered velocity model as wellas overcome ray density control problems in conventional methods. The test resultsrevealed this new method can be an effective modeling tool for accurate and effectivecomputing.