Scalar imaging condition for elastic reverse time migration
Scalar imaging condition for elastic reverse time migration
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DOI：
10.1190/geo2014-0453.1
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发表时间：
2015-06
期刊：
影响因子：
3.3
通讯作者：
Y. Duan;P. Sava
中科院分区：
文献类型：
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作者：
Y. Duan;P. Sava
弹性逆时偏移转换波成像的极性变化在地震勘探实验中叠加后会产生相消干扰。这种极性反转是由于PS和SP反射率在某些入射角下反转符号，例如，在各向同性介质中垂直入射。许多可用的极性校正方法是复杂的并且需要昂贵的变换，例如，到角度域。我们推导了一个简单的转换波成像条件，以校正图像极性，并揭示从一个波模式到另一个波模式的转换强度。我们的成像条件利用纯P-和S-模式得到亥姆霍兹分解。而不是相关的笛卡尔分量的矢量S-模式与P-模式，我们利用所有三个组件的S波场一次产生一个独特的图像。我们生成PS和SP图像使用的P-和S-波场的传播方向之间的几何关系，反射器的取向，和…
ABSTRACTPolarity changes in converted-wave images constructed by elastic reverse time migration cause destructive interference after stacking over the experiments of a seismic survey. This polarity reversal is due to PS and SP reflectivities reversing sign at certain incidence angles, e.g., at normal incidence in isotropic media. Many of the available polarity correction methods are complex and require costly transformations, e.g., to the angle domain. We derive a simple imaging condition for converted waves to correct the image polarity and reveal the conversion strength from one wave mode to another. Our imaging condition exploits pure P- and S-modes obtained by Helmholtz decomposition. Instead of correlating Cartesian components of the vector S-mode with the P-mode, we exploit all three components of the S wavefield at once to produce a unique image. We generate PS and SP images using geometric relationships among the propagation directions for the P- and S-wavefields, the reflector orientation, and th...