弹性波有限元反时偏移

THE FINITE ELEMENT REVERSE-TIME MIGRATION FOR ELASTIC WAVES

反时声波偏移法近来赢得了人们的普遍承认.与常规深度外推偏移法相比,这种方法所据有的便利之一是,它实际上对构造的倾角无任何限制,因此这种方法可用于复杂地质构造.基于反时外推的概念以及有限元技术,我们推导出了叠前对P波和S波同时偏移的表达式.本文列举了四个合成例子:(1)位于弹性半空间上的一水平弹性层,(2)位于弹性半空间上的一倾斜弹性层,(3)位于弹性半空间上的倾斜与水平弹性层的组合层,(4)弹性半空间上的二弹性层.现有的弹性波反时偏移算法从结果上来看是能处理复杂地质模型的.

The reverse-time acoustic wave migration method has recently gained in popularity. One of the advantages of the method over conventional depth extrapolation migration schemes is that there are virtually no restrictions on the dip angle of structures so that the method can be applied to complex geological structures.Based on the concept of reverse-time extrapolation and the finite element technique, a formulation for pre-stack P and S wave simultaneous migration has been developed. Four synthetic examples, including (1) an elastic horizontal layer over an elastic half-space, (2) an elastic dipping layer over an elastic half-space, (3) a composite elastic dipping and horizontal layer over an elastic half-space, and (4) two elastic layers over an elastic half-space, are presented. The present reverse-time elastic wave migration scheme appears to be capable of handling complex geological models.