Adaptive Spatial-division Split-step Fourier Migration Method  

自适应空间分区裂步傅立叶偏移方法(英文)

作　　者：赵景霞 张叔伦[1] 王昌龙[1] 倪逸 

机构地区：[1]大连理工大学 [2]大庆石油学院,大庆163311 [3]中油集团东方地球物理公司

出　　处：《Applied Geophysics》2005年第2期75-79,i0001,共6页应用地球物理（英文版）

摘　　要：This paper presents a new depth migration method, adaptive spatial-division split-step Fourier （ASDSSF） migration. In this method we introduce the idea of a stratified phase shift migration into the split-step Fourier （SSF） migration to make an accurate and efficient wave field image when sharp discontinuities appear in the velocity field. In principle, the ASDSSF migration is a multi-reference slowness （reciprocal of velocity） （MRS） migration. Compared to previous MRS migration methods, this method uses fewer reference slowness values without accuracy loss. The reference slowness is determined in this paper according to an error-control parameter of the perturbation term in the SSF operator and the variation of the complet velocity field. The velocity corresponded to reference slowness can define a spatial division. Each division can also be divided into several discontinuous spatial subdivisions to effectively reduce the number of reference slowness values needed. The choice of reference slowness, including the number of reference slowness values needed and how to construct the spatial divisions, is adaptive and reasonable at each extrapolation step （depth step）. A simple and economical smoothing filter in the wave number-frequency domain is designed to avoid artifacts in the wave field extrapolation due to the presence of sharp discontinuities in the velocity field. For comparable conditions the present approach to migration is expected to be computationally more efficient and accurate than other MRS migration methods. The performance of the method is demonstrated on a simple 2D prestack model and the prestack SEG/EAEG salt dataset.本文提出了一种新的偏移方法——自适应空间分区裂步傅立叶(ASDSSF)偏移方法。该方法将剥层相位移方法的思想推广到裂步傅立叶偏移方法,使之当速度场出现强间断时也能精确而有效地成像。原理上ASDSSF偏移属于多参考慢度(MRS)偏移方法,本文的重点是,在不损失精度的同时选取比同类MRS偏移方法更少的参考慢度。我们根据全局速度函数的变化和误差控制参数来选择参考慢度,同一个参考慢度所对应的速度构成一个分区,每一个空间分区可以由几个空间上不连续的子分区组成,从而有效地减小了参考慢度的个数。每一延拓步的参考慢度以及参考慢度的个数和如何构建分区都是根据速度函数自动生成,因此更为合理。为了消除速度场强间断产生的人为噪音,设计了简单有效的f-k域的光滑滤波。我们对一个生成的二维叠前模型和SEG/EAEG盐丘模型进行了试算。

关 键 词：MIGRATION spatial-division multi reference slowness ADAPTIVE and sharp discontinuity 

分 类 号：P631.4[天文地球—地质矿产勘探]