CAJ | 학술논문

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.
본문제출료일충신적편이방법--자괄응공간분구렬보부립협(ASDSSF)편이방법.해방법장박층상위이방법적사상추엄도렬보부립협편이방법,사지당속도장출현강간단시야능정학이유효지성상.원리상ASDSSF편이속우다삼고만도(MRS)편이방법,본문적중점시,재불손실정도적동시선취비동류MRS편이방법경소적삼고만도.아문근거전국속도함수적변화화오차공제삼수래선택삼고만도,동일개삼고만도소대응적속도구성일개분구,매일개공간분구가이유궤개공간상불련속적자분구조성,종이유효지감소료삼고만도적개수.매일연탁보적삼고만도이급삼고만도적개수화여하구건분구도시근거거속도함수자동생성,인차경위합리.위료소제속도장강간단산생적인위조음,설계료간단유효적f-k역적광활려파.아문대일개생성적이유첩전모형화SEG/EAEG염구모형진행료시산.
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.