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Multiparameter reflection waveform inversion for acoustic VTI media
Geophysical Prospecting ( IF 2.6 ) Pub Date : 2020-06-17 , DOI: 10.1111/1365-2478.12966 Yuanyuan Li 1 , Tariq Alkhalifah 1
Geophysical Prospecting ( IF 2.6 ) Pub Date : 2020-06-17 , DOI: 10.1111/1365-2478.12966 Yuanyuan Li 1 , Tariq Alkhalifah 1
Affiliation
ABSTRACT Full waveform inversion in transversely isotropic media with a vertical symmetry axis provides an opportunity to better match the data at the near and far offsets. However, multi‐parameter full waveform inversion, in general, suffers from serious cycle‐skipping and trade‐off problems. Reflection waveform inversion can help us recover a background model by projecting the residuals of the reflected wavefield along the reflection wavepath. Thus, we extend reflection waveform inversion to acoustic transversely isotropic media with a vertical symmetry axis utilizing the proper parameterization for reduced parameter trade‐off. From a radiation patterns analysis, an acoustic transversely isotropic media with a vertical symmetry axis is better described by a combination of the normal‐moveout velocity vn and the anisotropic parameters η and δ for reflection waveform inversion applications. We design a three‐stage inversion strategy to construct the optimal resulting model. In the first stage, we only invert for the background vn by matching the simulated reflected wavefield from the perturbations of vn and δ with the observed reflected wavefield. In the second stage, the background vn and η are optimized simultaneously and the far‐offset reflected wavefield mainly contribute to their updates. We perform Born modelling to compute the reflected wavefield for the two stages of reflection waveform inversion. In the third stage, we perform full waveform inversion for the acoustic transversely isotropic media with a vertical symmetry axis to delineate the high‐wavenumber structures. For this stage, the medium is described by a combination of the horizontal velocity vh, η and e instead of vn, η and δ. The acoustic multi‐parameter full waveform inversion utilizes the diving waves to improve the background as well as utilizes reflection for high‐resolution information. Finally, we test our inversion algorithm on the modified Sigsbee 2A model (a salt free part) and a two‐dimensional line from a three‐dimensional ocean bottom cable dataset. The results demonstrate that the proposed reflection waveform inversion approach can recover the background model for acoustic transversely isotropic media with a vertical symmetry axis starting from an isotropic model. This recovered background model can mitigate the cycle skipping of full waveform inversion and help the inversion recover higher resolution structures.
中文翻译:
声学 VTI 介质的多参数反射波形反演
摘要 具有垂直对称轴的横向各向同性介质中的全波形反演提供了更好地匹配近距和远距偏移处数据的机会。然而,多参数全波形反演通常存在严重的跳周期和权衡问题。反射波形反演可以通过沿反射波路径投影反射波场的残差来帮助我们恢复背景模型。因此,我们利用适当的参数化来减少参数权衡,将反射波形反演扩展到具有垂直对称轴的声学横向各向同性介质。从辐射模式分析,对于反射波形反演应用,通过法向时差速度 vn 和各向异性参数 η 和 δ 的组合可以更好地描述具有垂直对称轴的声学横向各向同性介质。我们设计了一个三阶段反演策略来构建最优结果模型。在第一阶段,我们仅通过将来自 vn 和 δ 扰动的模拟反射波场与观察到的反射波场相匹配来反演背景 vn。在第二阶段,同时优化背景 vn 和 η,远偏移反射波场主要有助于它们的更新。我们执行 Born 建模来计算反射波形反演的两个阶段的反射波场。在第三阶段,我们对具有垂直对称轴的声学横向各向同性介质进行全波形反演以描绘高波数结构。对于这个阶段,介质由水平速度 vh、η 和 e 的组合而不是 vn、η 和 δ 来描述。声学多参数全波形反演利用潜水波改善背景并利用反射获取高分辨率信息。最后,我们在修改后的 Sigsbee 2A 模型(无盐部分)和来自三维海底电缆数据集的二维线上测试我们的反演算法。结果表明,所提出的反射波形反演方法可以从各向同性模型开始恢复具有垂直对称轴的声学横向各向同性介质的背景模型。
更新日期:2020-06-17
中文翻译:
声学 VTI 介质的多参数反射波形反演
摘要 具有垂直对称轴的横向各向同性介质中的全波形反演提供了更好地匹配近距和远距偏移处数据的机会。然而,多参数全波形反演通常存在严重的跳周期和权衡问题。反射波形反演可以通过沿反射波路径投影反射波场的残差来帮助我们恢复背景模型。因此,我们利用适当的参数化来减少参数权衡,将反射波形反演扩展到具有垂直对称轴的声学横向各向同性介质。从辐射模式分析,对于反射波形反演应用,通过法向时差速度 vn 和各向异性参数 η 和 δ 的组合可以更好地描述具有垂直对称轴的声学横向各向同性介质。我们设计了一个三阶段反演策略来构建最优结果模型。在第一阶段,我们仅通过将来自 vn 和 δ 扰动的模拟反射波场与观察到的反射波场相匹配来反演背景 vn。在第二阶段,同时优化背景 vn 和 η,远偏移反射波场主要有助于它们的更新。我们执行 Born 建模来计算反射波形反演的两个阶段的反射波场。在第三阶段,我们对具有垂直对称轴的声学横向各向同性介质进行全波形反演以描绘高波数结构。对于这个阶段,介质由水平速度 vh、η 和 e 的组合而不是 vn、η 和 δ 来描述。声学多参数全波形反演利用潜水波改善背景并利用反射获取高分辨率信息。最后,我们在修改后的 Sigsbee 2A 模型(无盐部分)和来自三维海底电缆数据集的二维线上测试我们的反演算法。结果表明,所提出的反射波形反演方法可以从各向同性模型开始恢复具有垂直对称轴的声学横向各向同性介质的背景模型。