Frequency-dependent varying-step depth extrapolation scheme for wave equation based migration
波动方程深度偏移的频率相关变步长延拓方法

We propose a point wavefield interpolati frequency-dependent varying-step depth extrapolation scheme and a table-driven, oneon technique for the wave equation based migration methods. The former reduces the computational cost of wavefield depth extrapolation, and the latter reconstructs the extrapolated wavefield with an equal,desired vertical step with high computational efficiency. The proposed varying-step depth extrapolation plus one-point interpolation scheme results in 2/3 reduction in computational cost when compared to the conventional equal-step depth extrapolation of wavefield, but gives the almost same imaging. We present the scheme using the optimum split-step Fourier method on the 2-D Marmousi dataset and 3-D field dataset. The results demonstrate the high computational efficiency of the scheme in the absence of loss of accuracy. The proposed scheme can also be used by other wave equation based migration methods of the frequency domain.