地球物理学进展 ›› 2019, Vol. 34 ›› Issue (4): 1460-1464.doi: 10.6038/pg2019CC0229

• 应用地球物理学Ⅰ(油气及金属矿产地球物理勘探) • 上一篇    下一篇

初始模型对角度域偏移速度分析的影响

李江   

  1. 中煤科工集团西安研究院有限公司,西安 710077
  • 收稿日期:2018-09-09 修回日期:2019-05-21 出版日期:2019-08-20 发布日期:2019-08-30
  • 作者简介:李江,男,1985年生,陕西商洛人,博士,主要研究方向为地震数据处理方法.(E-mail: 2739594195@qq.com)
  • 基金资助:
    中国地质调查局地质调查项目(DD20160060)

Influence of the initial model on migration velocity analysis in angle domain

LI Jiang   

  1. CCTEG Xi’an Research Institute,Xi’an 710077,China
  • Received:2018-09-09 Revised:2019-05-21 Online:2019-08-20 Published:2019-08-30

摘要:

波动方程叠前深度偏移输出的角度域共成像点道集不仅包含着丰富的构造和岩性信息,而且直观地反映了偏移速度误差,非常适用于偏移速度分析.本文从角度域共成像点道集的剩余深度量方程出发,分析了初始速度模型存在正、负方向误差时对剩余深度量的影响,然后通过两组模型数据对理论分析的结果进行了测试和验证.结果表明,初始速度偏大时在角度域共成像点道集上能引起更大的剩余深度量,这更有利于判断速度误差并加快速度向正确的方向收敛,进而提高速度分析的精度和效率.因此,在角度域偏移速度分析中宜选择偏大的速度作为初始模型速度;在偏移结果受速度误差方向差异性影响的指导下,最终进行速度建模时,可以选择相对较小的速度值,因为偏小的速度对偏移结果影响相对较小.

关键词: 波动方程偏移, 角度域共成像点道集, 初始模型, 速度分析, 剩余深度

Abstract:

The angle domain common imaging gathers that come from wave equation migration not only contains tectonic and lithological information, but also reflects the migration velocity errors directly, so it is very suitable for the migration velocity analysis. In this paper, the influence of the initial velocity model with positive and negative direction errors on the residual depth is analyzed from the residual depth equation of the angle domain common image gathers. The results of theoretical analysis and two model tests showed that for the angle domain common imaging gather, the larger initial velocity, the larger residual depth, and which is more helpful to judge the velocity error and accelerate the convergence of the velocity to the correct direction, and then improve the accuracy and efficiency of the velocity analysis. Therefore, in the angle domain migration velocity analysis, the larger value should be selected as the initial model velocity. At the same time, under the guidance of the difference of velocity error in the direction of velocity error, when the velocity modeling is finally carried out, a relatively smaller velocity value should be chosen, because the smaller velocity has a smaller influence on the migration results.

Key words: Wave equation migration, Angle domain common image gather, Initial velocity model, Velocity analysis, Residual depth

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