Discrete earth models are commonly represented by uniform structured grids. In order to ensure accurate numerical description of all wave components propagating through these uniform grids, the grid size must be determined by the slowest velocity of the entire model. Consequently, high velocity areas are always oversampled, which inevitably increases the computational cost. A practical solution to this problem is to use nonuniform grids. We propose a nonuniform grid implicit spatial finite difference method which utilizes nonuniform grids to obtain high efficiency and relies on implicit operators to achieve high accuracy. We present a simple way of deriving implicit finite difference operators of arbitrary stencil widths on general nonuniform grids for the first and second derivatives and, as a demonstration example, apply these operators to the pseudo-acoustic wave equation in tilted transversely isotropic (TTI) media. We propose an efficient gridding algorithm that can be used to convert uniformly sampled models onto vertically nonuniform grids. We use a 2D TTI salt model to demonstrate its effectiveness and show that the nonuniform grid implicit spatial finite difference method can produce highly accurate seismic modeling results with enhanced efficiency, compared to uniform grid explicit finite difference implementations. © 2011 Elsevier B.V.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Applied Geophysics|
|State||Published - Jan 2012|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Stoffa would like to acknowledge the King Abdullah University of Science and Technology (KAUST) for their support of his research. We gratefully acknowledge the useful comments from two anonymous reviewers, which helped improve the original manuscript. We thank ConocPhillips for permission to publish this work.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.