Full-wavefield modeling and pre-stack depth migration of common-source seismic data

The goal of solving geophysical problems can be thought of as a data mapping or transform procedure. Through various techniques, the observed seismic data can be transformed into the solution domain to estimate the Earth properties. Seismic wave field simulation is a forward process used to synthesize the seismic responses of an Earth model. Seismic wave field imaging is an inverse process used to estimate the Earth parameters from observed seismic data. In this dissertation, finite-difference and pseudo-spectral computations, in two- and three-dimensional space, are used for full wave field simulations and imaging of common-source data.;Numerical simulation is developed for seismic sources and multi-attribute wave fields in two-dimensional acoustic and elastic media. P- and S-waves can be primarily separated in the resulting seismograms by vector operators in simulated surface survey, Vertical Seismic Profile (VSP) and cross-hole recording geometries. Three-component displacement seismograms can be approximately simulated by treating the acoustic field as a scalar potential field. The algorithm is applied to a complex multi-component, multi-offset walkaway circular VSP data from offshore California. Numerical modeling of large-scale, wide-aperture 3-D seismic data volumes is performed using a 3-D pseudo-spectral approach. Asymmetrical source and 3-D wave propagation effects in physical model data are identified and interpreted through iterative numerical modeling.;Prestack reverse-time migration algorithms based on finite-difference and pseudo-spectral wave field extrapolators are developed for acoustic media in two- and three-dimensions. The excitation time imaging condition is computed by ray tracing and by finite-difference solution of the Eikonal equation. I generalize the concept of reverse-time migration and apply it for the correction of near-surface static effects. The feasibility of using very large scale, very wide-aperture 3-D seismic data recorded on a areal grid for complex salt-imaging problems is demonstrated. Salt and subsalt structure imaging can be achieved in 3-D by using reverse-VSP data.