Three-dimensional Gauss–Newton constant- Q viscoelastic full-waveform inversion of near-surface seismic wavefields
Three-dimensional Gauss–Newton constant- Q viscoelastic full-waveform inversion of near-surface seismic wavefields
复制标题
近地表地震波场三维高斯牛顿常数-Q粘弹全波形反演
DOI：
10.1093/gji/ggac287
复制
发表时间：
2022
影响因子：
2.8
通讯作者：
Wang, Yao
中科院分区：
文献类型：
--
作者：
Mirzanejad, Majid;Tran, Khiem T.;Wang, Yao
全波形反演(FWI)方法依赖于波在被分析介质中传播的精确数值模拟。声波或弹性波方程常被用来模拟地震波的传播。这些类型的模拟没有考虑材料滞弹性引起的固有衰减效应，因此在实践中使用了修正技术来部分补偿滞弹性。这些技术通常只考虑基于整个数据集的总幅度响应的平均的波形幅度校正，而忽略了相位校正。粘弹性波动方程同时考虑了波形的幅值和相位的滞弹性响应，因此是一种更合适的选择。在这项研究中，我们提出了一种新的三维高斯-牛顿粘弹性傅里叶变换(3-D GN-VFWI)方法。为了解决高斯-牛顿优化的主要挑战，我们提出了通过虚源和反向波场的卷积来有效地计算雅可比的公式。通过直接对粘弹性波动方程对模型参数进行微分化得到了虚源。为了以合理的计算工作量来求解复杂的三维结构，在整个分析过程中使用了均匀衰减(Q因子)来模拟滞弹性效应。通过模拟实验和现场实验，验证了该方法的有效性。合成结果清楚地表明了该方法能够刻画具有挑战性的速度剖面，包括空洞和反向速度层。现场实验结果表明，该方法成功地刻画了具有两个空洞和起伏的石灰岩基岩的复杂的子结构，并得到了侵入测试的证实。与三维弹性FWI结果相比，本文提出的粘弹性方法对孔洞和基岩的深度有更高的精度。这项研究表明，成像精度的提高将保证粘弹性波动方程在FWI问题中的广泛使用。据我们所知，这是第一个报道的任何规模的3D GN-VFWI研究。该研究为高斯-牛顿优化方法在三维粘弹性问题中的应用提供了新的理论和公式。
Full-waveform inversion (FWI) methods rely on accurate numerical simulation of wave propagation in the analysed medium. Acoustic or elastic wave equations are often used to model seismic wave propagation. These types of simulations do not account for intrinsic attenuation effects due to material anelasticity, and thus correction techniques have been utilized in practice to partially compensate the anelasticity. These techniques often only consider the waveform amplitude correction based on averaging of overall amplitude response over the entire data set, and ignore the phase correction. Viscoelastic wave equations account for the anelastic response in both waveform amplitude and phase, and are therefore a more suitable alternative. In this study, we present a novel 3-D Gauss–Newton viscoelastic FWI (3-D GN-VFWI) method. To address the main challenge of the Gauss–Newton optimization, we develop formulas to compute the Jacobian efficiently by the convolution of virtual sources and backward wavefields. The virtual sources are obtained by directly differentiating the viscoelastic wave equations with respect to model parameters. In order to resolve complex 3-D structures with reasonable computational effort, a homogeneous attenuation (Qfactor) is used throughout the analysis to model the anelastic effects. Synthetic and field experiments are performed to demonstrate the utility of the method. The synthetic results clearly demonstrate the ability of the method in characterizing a challenging velocity profile, including voids and reverse velocity layers. The field experimental results show that method successfully characterizes the complex substructure with two voids and undulating limestone bedrock, which are confirmed by invasive tests. Compared to 3-D elastic FWI results, the presented viscoelastic method produces more accurate results regarding depths of the voids and bedrock. This study suggests that the improvement of imaging accuracy would warrant the widespread use of viscoelastic wave equations in FWI problems. To our best knowledge, this is the first reported study on 3-D GN-VFWI at any scale. This study provides the new theory and formulation for the use of Gauss–Newton optimization on the 3-D viscoelastic problem.