Article,
Velocity model estimation with data-derived wavefront attributes
Geophysics, 69 (1): 265--274 (Jan 1, 2004)
DOI: 10.1190/1.1649394
Abstract
Kinematic information for constructing velocity models can be extracted
in a robust way from seismic prestack data with the common-reflection-surface
(CRS) stack. This data-driven process results, in addition to a simulated
zero-offset section, in a number of wavefront attributes - wavefront
curvatures and normal ray emergence angles - associated with each
simulated zero-offset sample. A tomographic inversion method is presented
that uses this kinematic information to determine smooth, laterally
heterogeneous, isotropic subsurface velocity models for depth imaging.
The input for the inversion consists of wavefront attributes picked
at a number of locations in the simulated zero-offset section. The
smooth velocity model is described by B-splines. An optimum model
is found iteratively by minimizing the misfit between the picked
data and the corresponding modeled values. The required forward-modeled
quantities are obtained during each iteration by dynamic ray tracing
along normal rays pertaining to the input data points. Frechet derivatives
for the tomographic matrix are calculated by ray perturbation theory.
The inversion procedure is demonstrated on a 2D synthetic prestack
data set.
