Migration of dispersive GPR data
Migration of dispersive GPR data
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发表时间：
2004-06
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通讯作者：
M. Powers;C. Oden
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作者：
M. Powers;C. Oden
导电性以及介电和磁弛豫现象导致电磁传播在地球材料中分散。速度和衰减都可能随频率而变化，具体取决于传播能量的频率含量和弛豫现象的性质。少量的速度色散与高衰减相关。因此，测量探地雷达 (GPR) 数据中速度色散的影响很困难。通过色散前向模型，已经创建了探地雷达对通过具有已知频率相关特性的材料传播的响应。这些响应用作迁移算法的测试数据，这些算法已被修改以处理色散介质的特定方面。当修改 Stolt 或 Gazdag 偏移方法以仅校正速度离散时，结果与标准偏移几乎没有变化。对于非色散传播波场数据（例如深部地震），确保偏移算法中正确的相位求和比正确处理幅度更重要。然而，使用修改后的算法将模型响应迁移到色散介质的结果表明，在这种情况下，校正频率相关的幅度损失对结果的影响比校正适当的相位总和要大得多。修改后的偏移仅在包括衰减恢复、同时执行反卷积和偏移时才有效。
Electrical conductivity and dielectric and magnetic relaxation phenomena cause electromagnetic propagation to be dispersive in earth materials. Both velocity and attenuation may vary with frequency, depending on the frequency content of the propagating energy and the nature of the relaxation phenomena. A minor amount of velocity dispersion is associated with high attenuation. For this reason, measuring effects of velocity dispersion in ground penetrating radar (GPR) data is difficult. With a dispersive forward model, GPR responses to propagation through materials with known frequency-dependent properties have been created. These responses are used as test data for migration algorithms that have been modified to handle specific aspects of dispersive media. When either Stolt or Gazdag migration methods are modified to correct for just velocity dispersion, the results are little changed from standard migration. For nondispersive propagating wavefield data, like deep seismic, ensuring correct phase summation in a migration algorithm is more important than correctly handling amplitude. However, the results of migrating model responses to dispersive media with modified algorithms indicate that, in this case, correcting for frequency-dependent amplitude loss has a much greater effect on the result than correcting for proper phase summation. A modified migration is only effective when it includes attenuation recovery, performing deconvolution and migration simultaneously.