A numerically exact local solver applied to salt boundary inversion in seismic full-waveform inversion
A numerically exact local solver applied to salt boundary inversion in seismic full-waveform inversion
复制标题
应用于地震全波形反演盐边界反演的数值精确局部求解器
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Winston Lewis
中科院分区：
文献类型：
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作者：
Bram Willemsen;A. Malcolm;A. Malcolm;Winston Lewis
在从四维地震到SALT边界估计的一系列问题中，速度模型的更新通常具有高度局部化的性质。用于这些应用的数值技术，例如全波形反演(FWI)，需要对波场进行估计以计算模型更新。在处理局部问题时，当我们只在感兴趣的区域中需要这些更新时，在全局域中计算这些更新是浪费的。本文介绍了一种局部求解器，它产生的正向波场和伴随波场与在感兴趣区域内评估的全域求解器所产生的波场在机器精度上是相同的。这意味着局部解算器计算感兴趣区域内的模型更新与外部背景模型中的不均匀之间的所有交互。因为在计算前向波场和伴随波场时没有进行任何近似，所以局部求解器可以计算感兴趣区域中与更昂贵的全域求解器所计算的相同的梯度。本文利用局部求解器有效地生成了盐体边界上的FWI梯度。然后，在水平集方法中使用该梯度来自动更新盐度边界。
In a set of problems ranging from 4-D seismic to salt boundary estimation, updates to the velocity model often have a highly localized nature. Numerical techniques for these applications such as full-waveform inversion (FWI) require an estimate of the wavefield to compute the model updates. When dealing with localized problems, it is wasteful to compute these updates in the global domain, when we only need them in our region of interest. This paper introduces a local solver that generates forward and adjoint wavefields which are, to machine precision, identical to those generated by a full-domain solver evaluated within the region of interest. This means that the local solver computes all interactions between model updates within the region of interest and the inhomogeneities in the background model outside. Because no approximations are made in the calculation of the forward and adjoint wavefields, the local solver can compute the identical gradient in the region of interest as would be computed by the more expensive full-domain solver. In this paper, the local solver is used to efficiently generate the FWI gradient at the boundary of a salt body. This gradient is then used in a level set method to automatically update the salt boundary.