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深水勘探近年来成为海上勘探的热点,这不可避免会碰到崎岖海底的情况。在崎岖海底的地震资料中,地震波的传播路径受海底影响严重畸变,速度横向变化剧烈,导致下伏地层严重扭曲变形,时间偏移无论叠前还是叠后均不能改变这种情况。三维叠前深度偏移对构造复杂及速度的横向变化均没有条件限制,所以成为解决崎岖海底成像的有力工具。本文即以南海珠江口盆地某区的叠前深度偏移处理为例,阐述其处理的过程、涉及的方法和取得的效果。其中技术包括海上资料预处理、海底层位的建立、CVI约束速度反演、梯度的引进,实体模型的建立,全局层析优化等等。
Deepwater exploration has become a hot spot for exploration in the sea in recent years, which inevitably encounters the situation of the rugged seafloor. In the seismic data of the rugged seafloor, the propagation path of seismic waves is seriously distorted by the seafloor, and the lateral velocity changes drastically. As a result, the underlying strata are severely distorted, and the time migration can not be changed either prestack or poststack. The 3D prestack depth migration has no restriction on the complicated structure and the horizontal variation of velocity, so it becomes a powerful tool to solve the rough seafloor imaging. In this paper, taking the treatment of prestack depth migration in a certain area of the Pearl River Mouth Basin in the South China Sea as an example, the paper deals with the process, the methods involved and the results obtained. Among them, the technologies include the preprocessing of marine data, the establishment of submarine horizon, the inversion of CVI constrained velocity, the introduction of gradient, the establishment of solid model, global optimization and so on.