A Strategy For Attenuating VSP Migration Artifacts: Local Beam Migration
A Strategy For Attenuating VSP Migration Artifacts: Local Beam Migration
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DOI：
10.1190/1.3064047
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
Jianhua Yu;B. Hornby
中科院分区：
文献类型：
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作者：
Jianhua Yu;B. Hornby
VSP导出的图像可能遭受严重的偏移伪影，其中由波动方程和基于射线的偏移方法产生的偏移“微笑”没有被完全抵消。这些伪影主要是由于有限的采集孔径和有限的接收器阵列用于数据采集。这对于复杂盐结构下方的沉积物尤其重要，其中所需数据不仅包含感兴趣的信号，还包含强烈的不希望的衍射和由尖锐的速度对比引起的其他到达。在这项工作中，我们演示了如何提高偏移图像质量的波场分解成局部光束在偏移过程中，并使用广义成像条件优化分解的局部光束。对合成数据和野外数据的试验表明，该偏移方法能够有效地消除偏移伪影，得到噪声较小的成像结果。然而，在处理高角度结构（如断层和盐翼）时，需要注意更多的光束。
VSP-derived images can suffer from severe migration artifacts where the migration "smiles" resulting from the wave-equation and ray-based migration approaches are not be canceled out completely. These artifacts primarily result from limited acquisition aperture and limited receiver array used in the data acquisition. This can be especially important with sediments below a complicated salt structure where the desired data contains not only signals of interest but strong undesired diffractions and other arrivals caused by the sharp velocity contrast. In this work, we demonstrate how to improve migration image quality by decomposing wavefields into local beams in the migration process and optimizing the decomposed local beams using a generalized imaging condition. Tests on synthetic and field data indicate that this migration scheme is capable of attenuating migration artifacts and yields the image with less noise. However, some care should be taken when dealing with high angle structure such as faults and salt flanks where more beams will be required.