A randomized method for one-step extrapolation in reverse time migration

摘要

Reverse time migration has drawn great attention in exploration geophysics because it can be used successfully in areas with large structural and velocity complexity. But its computational cost is considerably high. This paper concerns the fast implementation of the optimized separable approximation of the two-way propagator, which is the most computational expensive step in reverse time migration. On the basis of the low-rank property of the propagator and the idea of randomized algorithm, a randomized method is introduced for optimized separable approximation-based one-step extrapolation. Numerical results of approximating the propagator show that the randomized method is more efficient than the conventional interpolation method. At the same time, numerical experiments of wavefield extrapolation show that the proposed method is much more accurate than the conventional finite-difference plus pseudo-spectrum scheme. Copyright (c) 2014 John Wiley & Sons, Ltd.