Scattering pattern analysis and true-amplitude generalized Radon transform migration for acoustic transversely isotropic media with a vertical axis of symmetry
Scattering pattern analysis and true-amplitude generalized Radon transform migration for acoustic transversely isotropic media with a vertical axis of symmetry
复制标题
具有垂直对称轴的声横观各向同性介质的散射模式分析和真振幅广义Radon变换偏移
DOI：
10.1111/1365-2478.12921
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发表时间：
2020
影响因子：
2.6
通讯作者：
Cheng Shijun
中科院分区：
文献类型：
--
作者：
Liang Quan;Ouyang Wei;Mao Weijian;Cheng Shijun
在基于多参数射线的各向异性偏移/反演中，我们必须了解与参数扰动相对应的散射机制。由于各向异性反演问题中的复杂非线性是难以处理的，因此真振幅线性化偏移/反演过程的构造是必要的并且是重要的。利用具有垂直对称轴的横观各向同性介质的声学介质假设，用P波法向时差速度、泊松参数δ和非椭圆参数η表示各向异性，将三维拟声波方程的线性化逆散射问题形式化。部署单次散射近似和椭圆各向异性背景引入了一种新的线性积分算子，该算子将不连续扰动参数与多炮点/多炮检距P波散射数据联系起来。我们进一步将高频渐近绿色函数及其导数应用于积分算子，然后可以显式地表示每个扰动参数的散射模式。通过自然地建立与广义Radon变换的联系，积分算子的伪逆可以通过广义Radon变换逆来求解。考虑到该伪逆算子的结构，通过从目标成像区域朝向采集系统发射一扇射线来逐点进行计算实现。二维数值测试的结果显示了高质量的振幅保持图像。
In multi‐parameter ray‐based anisotropic migration/inversion, it is essential that we have an understanding of the scattering mechanism corresponding to parameter perturbations. Because the complex nonlinearity in the anisotropic inversion problem is intractable, the construction of true‐amplitude linearized migration/inversion procedures is needed and important. By using the acoustic medium assumption for transversely isotropic media with a vertical axis of symmetry and representing the anisotropy with P‐wave normal moveout velocity, Thomsen parameter δ and anelliptic parameter η, we formalize the linearized inverse scattering problem for three‐dimensional pseudo‐acoustic equations. Deploying the single‐scattering approximation and an elliptically anisotropic background introduces a new linear integral operator that connects the discontinuous perturbation parameters with the multi‐shot/multi‐offset P‐wave scattered data. We further apply the high‐frequency asymptotic Green's function and its derivatives to the integral operator, and then the scattering pattern of each perturbation parameter can be explicitly presented. By naturally establishing a connection to generalized Radon transform, the pseudo‐inverse of the integral operator can be solved by the generalized Radon transform inversion. In consideration of the structure of this pseudo‐inverse operator, the computational implementation is done pointwise by shooting a fan of rays from the target imaging area towards the acquisition system. Results from two‐dimensional numerical tests show amplitude‐preserving images with high quality.