TI介质局部角度域高斯束叠前深度偏移成像

各向异性射线理论基础上的局部角度域叠前深度偏移方法能够为深度域构造成像与基于角道集的层析反演提供有力支撑，但是对于复杂地质构造而言，高斯度叠前深度偏移在不失高效、灵活等特点的情况下，具有明显的精度优势.为此，本文研究局部角度域理论框架下的高斯束叠前深度偏移方法.为提高算法效率与实用性，文中讨论了一种从经典弹性参数表征的各向异性介质运动学和动力学射线方程演变而来的由相速度表征的简便形式，并提出了一种比较经济的各向异性高斯束近似合成方案.结合地震波局部角度域成像原理，讨论一种适合高斯束偏移的角度参数计算方法.国际上通用的理论模型合成数据试验表明：相比局部角度域Kirchhoff叠前深度偏移成像方法，本文方法具有更高的成像精度与抗噪能力，既适用于复杂构造成像，也可为TI介质深度域偏移速度分析与模型建立提供高效的偏移引擎.

Local angle-domain Gaussian beam prestack depth migration in a TI medium

Angle-domain prestack depth migration based on anisotropic ray theory can provide strong support to the structural imaging in the depth domain and angle-gather-based seismic tomography. The Gaussian beam prestack depth migration has shown its great advantages in accuracy of complex structural imaging, computational efficiency and flexibility. In this paper, we focus on implementing Gaussian beam perstack depth migration in the framework of local angle domain imaging. In order to improve the efficiency and practicability of proposed algorithm, we discuss a kind of phase velocity based kinematic and dynamic ray tracing systems, which is evolved from the classic ray tracing equation of anisotropic media. And we propose a more economical program for constructing anisotropic Gaussian beams. Combined with the principle of seismic local angle domain imaging, we discuss an angle parameter calculation method which is suitable for Gaussian beam migration. Numerical tests on the standard theoretical anisotropic models show that compared with local angle domain Kirchhoff migration, our approach has a higher imaging precision and better anti-noise ability. It also can be used as an imaging tool for complex geological structures and efficient migration engine for anisotropic migration velocity analysis and model construction.