Seismic diffractions from small-scale discontinuities or inhomogeneities carry key geologic information and can provide high-resolution images of these objects. Because diffractions characterized by weak energy are easily masked by strong reflections, diffraction-enhancement processing is essential before subwavelength information detection. Therefore, a novel diffraction-separation method is developed that uses the Fourier-based geometric-mode decomposition (GMDF) algorithm to remove reflections and separate diffractions in the common-offset or poststack domain. The key idea of our method is that, in the frequency-wavenumber (f-k) domain, strong reflections concentrate linearly along a certain dip direction, whereas weak diffractions are distributed over a wide range of wavenumbers owing to their variable dips in the time-space domain. The GMDF algorithm can effectively represent reflections with directional and linear geometric features by adaptively decomposing seismic data as a combination of the band-limited modes consisting of linear characteristics in the f-k domain. The alternating direction method of the multipliers algorithm is used to solve the GMDF optimization problem and obtain linear reflections. Because this method considers the energy sparsity property and linear geometric features of reflections in the f-k domain, kinematic and dynamic differences between reflections and diffractions are exploited to separate diffractions. Applied synthetic and field examples demonstrate the good performance of our method in removing strong reflections and separating weak diffractions, providing interpreters with detailed structural and stratigraphic information.

中文翻译：

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使用几何模式分解的地震衍射的分离和成像

来自小规模不连续性或不均匀性的地震衍射携带着关键的地质信息，可以提供这些物体的高分辨率图像。由于以弱能量为特征的衍射容易被强反射所掩盖，因此在亚波长信息检测之前必须进行衍射增强处理。因此，开发了一种新的衍射分离方法，该方法使用基于傅立叶的几何模式分解 (GMDF) 算法来去除共偏移距或叠后域中的反射和分离衍射。我们方法的关键思想是，在频率波数 ( f - k) 域，强反射沿某个倾角方向线性集中，而弱衍射由于它们在时空域中的可变倾角而分布在广泛的波数范围内。GMDF算法通过将地震数据自适应分解为f - k域中由线性特征组成的带限模式的组合，可以有效地表示具有方向性和线性几何特征的反射。利用乘子算法的交替方向法求解GMDF优化问题，得到线性反射。由于该方法考虑了f - k中反射的能量稀疏性和线性几何特征利用反射和衍射之间的域、运动学和动态差异来分离衍射。应用的合成和现场示​​例证明了我们的方法在去除强反射和分离弱衍射方面的良好性能，为解释人员提供了详细的结构和地层信息。