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Prestack diffraction separation in the common virtual source gather
Geophysics ( IF 3.3 ) Pub Date : 2021-02-05 , DOI: 10.1190/geo2020-0105.1
Chuangjian Li 1 , Jingtao Zhao 2 , Suping Peng 2 , Xiaoqin Cui 2
Affiliation  

Diffractions are the seismic responses of subsurface small-scale geologic discontinuities or inhomogeneities, whose energy is much weaker than that of reflections. To eliminate the masking effect of strong reflections on weak diffractions, a prestack diffraction separation method is proposed based on the common virtual source gather (CVSG) and the median filter. The reflection generated from a reflector can be regarded as originating from a virtual source (or a focused area). According to this behavior, the reflection can be transformed into its corresponding virtual source position to build the CVSG. Unlike the reflection, diffraction cannot be regarded as originating from one virtual source. Therefore, diffractions have a curved shape, whereas reflections are flat in the CVSG. Based on the traveltime moveout method, the reflection traveltime is calculated for describing reflection events and generating CVSG. Theory and a simple synthetic data test demonstrate that there is almost no energy lost when transforming between a shot gather and CVSG. Then, for removing the reflection, the median filter is used in the CVSG where the reflection appears as a linear event. Complex synthetic and field examples demonstrate that the proposed method can flatten reflection events and thus can separate diffraction events from strong reflections in the prestack domain.

中文翻译:

常见虚拟源集合中的叠前衍射分离

衍射是地下小规模地质不连续性或不均匀性的地震反应,其能量比反射的能量弱得多。为了消除强反射对弱衍射的掩盖效应,提出了一种基于共同虚拟源集(CVSG)和中值滤波器的叠前衍射分离方法。从反射器产生的反射可以被视为源自虚拟源(或聚焦区域)。根据此行为,可以将反射转换为其对应的虚拟源位置,以构建CVSG。与反射不同,不能将衍射视为源自一个虚拟源。因此,衍射具有弯曲的形状,而在CVSG中反射是平坦的。根据出差时差方法,计算反射行程时间以描述反射事件并生成CVSG。理论和简单的综合数据测试表明,在击球道和CVSG之间转换时几乎没有能量损失。然后,为了消除反射,在CVSG中使用中值滤波器,其中反射表现为线性事件。复杂的合成和野外实例表明,所提出的方法可以使反射事件平坦化,因此可以在叠前区域将衍射事件与强反射分开。在CVSG中使用中值滤波器,其中反射显示为线性事件。复杂的合成和野外实例表明,所提出的方法可以使反射事件平坦化,因此可以在叠前区域将衍射事件与强反射分开。在CVSG中使用中值滤波器,其中反射显示为线性事件。复杂的合成和野外实例表明,所提出的方法可以使反射事件平坦化,因此可以在叠前区域将衍射事件与强反射分开。
更新日期:2021-02-07
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