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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。
In this paper, we propose a new migration method, Adaptive Spatial Partition Cracking Fourier (ASDSSF) migration method. This method extends the idea of the phase-shift method of the peeling layer to the method of split-step Fourier migration so that it can accurately and effectively image when the velocity field is strongly interrupted. In principle, the ASDSSF offset belongs to the MRS offset method. The emphasis of this paper is to select less reference slowness than the MRS offset method without loss of accuracy. We select the reference slowness according to the global speed function change and the error control parameters. The speed corresponding to the same reference slowness constitutes a partition, and each spatial partition can be composed of several spatially discontinuous sub-partitions, so as to effectively Reduce the number of reference slowness. The reference slowness of each extension step, as well as the number of reference slownesses and how to construct the partition are automatically generated based on the speed function, so it is more reasonable. In order to eliminate the man-made noise caused by the intermittent speed field, a simple and effective smoothing filter for f-k domain is designed. We performed a trial of a two-dimensional prestack model and a SEG / EAEG salt dome model.