3D Kirchhoff prestack time migration in average illumination-azimuth and incident-angle domain for isotropic and vertical transversely isotropic media
3D Kirchhoff prestack time migration in average illumination-azimuth and incident-angle domain for isotropic and vertical transversely isotropic media
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DOI：
10.1190/1.3533913
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发表时间：
2011-01
期刊：
影响因子：
3.3
通讯作者：
Jiubing Cheng;J. Geng;Huazhong Wang;Z. Ma
中科院分区：
文献类型：
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作者：
Jiubing Cheng;J. Geng;Huazhong Wang;Z. Ma
传统的偏移距域叠前偏移会使不同角度的能量在像点处模糊，容易产生模糊和偏移伪影。为了避免这种情况，在过去的几十年中，叠前深度偏移的角度域的实现进行了研究。角度域克希霍夫叠前时间偏移是近年来提出的一种有效的成像方法。然而，现有的算法无法正确处理射线弯曲和各向异性。在实际应用中，对于裂缝性储层，大多数地质条件下都需要在偏移后进行方位分析。遗憾的是，现有的偏移算法隐含地涉及到对源-接收器方位角的某种面元化，其可能不是真实的波路径方位角，特别是对于侧向散射或平面外波。本文提出了一种在平均照明方位角和入射角域进行三维克希霍夫叠前时间偏移的算法，该算法能更自然、更精确地匹配真实波道。为了处理射线弯曲和垂直横观各向同性，我们提出了几种方法来估计双向旅行时和相应的角度属性，通过扩展的偏移到角度映射。基于这些方法，我们的三维叠前时间偏移可以提供高质量的共像道集的振幅变化与入射角和/或振幅变化与偏移距和方位角分析，即使在介质中有轻微到中度的横向非均匀性。二维和三维的合成实例证明了本文方法的有效性。
Conventional offset domain prestack migration tends to bring ambiguity and migration artifacts because it smears energy from different angles at the image point. To avoid this, prestack depth migration implementations in angle domain have been investigated in the past decades. As an efficient imaging tool, angle domain Kirchhoff prestack time migration is still useful and was proposed recently. However, existing algorithms cannot handle ray bending and anisotropy correctly. Practically, azimuth analysis for fractured reservoirs should be carried out after migration for most geological settings. Unfortunately, the existing migration algorithm implicitly involves some kind of binning to source-receiver azimuth, which may not be the real wave-path azimuth, especially for side-scattering or out-of-plane waves. In this paper, we present an algorithm for 3D Kirchhoff prestack time migration in average illumination azimuth and incident angle domain, which matches true wave path naturally and more accurately. To handle ray bending and vertical transversely isotropy, we propose several approaches to estimate two-way traveltime and the corresponding angular attributes through extended offset-to-angle mapping. Based upon these approaches, our 3D prestack time migration can provide high-quality common-image gathers for amplitude variation with incident angle and/or amplitude variation with offset and azimuth analyses, even in media with slight to moderate lateral heterogeneity. The 2D and 3D synthetic examples prove the validity of our methods.