ABSTRACT The wavelet stretch effects in pre-stack migration, which is similar to that of NMO stretch, distort the frequency spectrums and taper the high-frequency components at far offsets. The long-offset migrated results in conventional migration methods are muted, resulting in a loss of effective information about the subsurface investigation. Only short-offset data are used to obtain a high-resolution stacked image. However, long-offsets that correspond to high-incident-angle data are critical to velocity inversion and amplitude versus offset (AVO) analysis when estimating lithology and fluid product. Furthermore, attenuation of seismic waves due to the anelasticity of the subsurface medium will cause dissipation of seismic energy and loss of high frequencies, thus broadening the propagating wavelet and degrading the resolution of imaging. Both the wavelet stretch and the absorption will taper the high-frequency components. We developed a wavelet stretch correction and absorption compensation scheme during the migration process by shrinking the wavelet when applying the imaging condition, which matches the stretch effect caused by migration. The correction factor is derived based on the incidence angle associated with many factors. Moreover, the de-absorption pre-stack time migration (QPSTM) is implemented on the effective Q model that makes the Q modelling become easier. Both the application of synthetic and real data examples demonstrate that the proposed anti-stretch QPSTM can be particularly useful recovering the high-frequency components caused by anelasticity and wavelet stretch, and obtain higher-resolution images.

中文翻译：

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高分辨率成像：反吸收叠前时间偏移方法中的小波拉伸校正

摘要 叠前偏移中的小波拉伸效应与 NMO 拉伸类似，会扭曲频谱并使远偏移距处的高频分量逐渐变细。传统偏移方法中的长偏移偏移结果被忽略，导致有关地下调查的有效信息丢失。仅使用短偏移量数据来获得高分辨率堆叠图像。然而，在估计岩性和流体产品时，对应于高入射角数据的长偏移量对于速度反演和振幅与偏移量 (AVO) 分析至关重要。此外，由于地下介质的非弹性，地震波的衰减会引起地震能量的耗散和高频的损失，从而使传播的小波变宽，降低成像的分辨率。小波拉伸和吸收都会使高频分量逐渐变细。我们通过在应用成像条件时缩小小波，在偏移过程中开发了小波拉伸校正和吸收补偿方案，这与偏移引起的拉伸效应相匹配。校正因子是基于与许多因素相关的入射角得出的。此外，在有效 Q 模型上实现了解吸收叠前时间偏移（QPSTM），使 Q 建模变得更加容易。合成和真实数据示例的应用表明，所提出的抗拉伸 QPSTM 在恢复由弹性和小波拉伸引起的高频分量方面特别有用，并获得更高分辨率的图像。