Amplitude-preserved common image gathers by wave-equation migration
Amplitude-preserved common image gathers by wave-equation migration
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DOI：
10.1190/1.1816598
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
P. Sava;B. Biondi;Sergey Fomel
中科院分区：
文献类型：
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作者：
P. Sava;B. Biondi;Sergey Fomel
提出了两种利用向下延拓偏移计算角域共像道集(ADCIG)的方法，并分析了它们的幅度响应与反射角(AVA)的关系。这两种方法的直接实施会导致相互矛盾的幅度响应，因此显然不准确。振幅问题与向下延拓偏移是向上延拓模拟的伴随项有关，但它是对其逆的较差逼近。我们推导了在频率-波数域中对角线的加权算子，这使得偏移很好地近似于模拟的逆。加权后，两种方法计算的ADCIGs趋于一致。在实际情况中降低AVA精度的其他重要因素是有限的采样和偏移距范围，以及地震数据的带限性质。
We present two methods to compute angle-domain common image gathers (ADCIG) by downward-continuation migration, and we analyze their amplitude response versus reflection angle (AVA). A straightforward implementation of the two methods leads to contradictory, and thus obviously inaccurate, amplitude responses. The amplitude problem is related to the fact that downward continuation migration is the adjoint of upward-continuation modeling, but it is a poor approximation of its inverse. We derive the weighting operators, diagonal in the frequency-wavenumber domain, that makes migration a good approximation to the inverse of modeling. After weighting, the ADCIGs computed by the two methods become consistent. Other important factors degrading the accuracy of AVA in practical situation are the limited sampling and offset range, and the bandlimited nature of seismic data.