The Amplitude-Preserving Characteristics of Converted Wave Prestack Time Migration by Pseudo Offset Migration

摘要

POM (Pseudo Offset Migration) is an important method for Converted Wave Prestack Time Migration.Since POM doesn't put the pseudo shot and the pseudo receiver at the same point,the ray path of POM meets the Snell's Law.And then,the true common reflection point gathers can be extracted.In this paper,pseudo offset formula is deduced separately under two different extreme conditions.And a amplitude-preserving migration weight function is lead up to test the characteristic of converted wave POM imaging.The imaging difference of amplitude-preserving and non-amplitude-preserving are analyzed and compared.The result shows that the time-distance curve's hyperbolic characteristics of amplitude-preserving CCSP gathers formed by POM are more closer to the actuary circumstances,with low noise and without losing the dynamic characteristics of wave propagation after the Pseudo Offset's "Pseudo".The common conversion scatter point gathers from POM have higher velocity analysis accuracy.So POM method can get a better imaging result.