三维共散射点道集叠前时间偏移速度分析

Pre-stack time migration and velocity analysis on 3D common scattering gathers

基于共散射点(CSP)道集的叠前时间偏移速度分析方法的理论基础是散射理论和Kirchhoff积分偏移方法。等价炮检距为研究叠前地震偏移和速度估计方法提供了新的思路。本文首先阐述了二维情况下单平方根旅行时方程的推导,以及共散射点道集的提取与构建,总结了共散射点道集的优势;在此基础上研究了三维情况下共散射点道集映射原理、构建方法及速度分析方法。实际三维资料的试算表明,共散射点道集对应的速度谱和叠前时间偏移剖面的精度高于常规CMP道集对应的速度谱和叠前时间偏移剖面。

Scattering theory and Kirchhoff pre-stack time migration methods are the theory basis of pre-stack time migration and velocity analysis methods on common scattering point(CSP) gathers.The concept of equivalent offset proposed in the paper provides a new approach for pre-stack migration and velocity analysis.This paper first derives a new kind of single-square-root travel-time equation,and a method to obtain CSP gathers,and summarize the advantage of CSP gathers compared to CMP gathers.And then the paper develops a CSP gathers method to 3D geometry data.Through the processing to 3D model and field data,it is clear that the quality of semblances and the imaging on CSP methods are better than those of CMP gathers.