arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2610.15331cs.LGphysics.geo-ph
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结合学习到的预条件子的全波形反演

Full Waveform Inversion with a Learned Preconditioner

Jeongjin Park

AI总结:

本研究探究用基于RTM图像训练的神经算子作为FWI预条件子,发现JI-FNO预条件子性能最优,还揭示了非线性神经高斯-牛顿内求解的失效模式,明确了准确导数与目标一致使用的重要性。

摘要:

全波形反演(Full-waveform inversion, FWI)是重建地下速度模型的强大方法,但其实际性能受限于病态性、对更新方向的敏感性以及基于曲率的方法的高成本。在本研究中,我们探究基于逆时偏移(reverse-time-migration, RTM)图像训练的神经算子是否能为FWI提供有用的学习预条件子。我们对比了投影FWI与使用标准傅里叶神经算子(Fourier neural operator, FNO)或雅可比信息型FNO(Jacobian-informed FNO, JI-FNO)的神经预条件FWI。该神经预条件子将学习到的RTM映射的法向算子应用于修改真实的Devito FWI梯度。实验结果显示,JI-FNO预条件子在保持与基线投影FWI相当的数据残差衰减的同时,实现了最低的模型误差;相比之下,标准FNO预条件子虽采用相同的神经预条件框架,却不稳定且模型恢复效果更差。我们还发现了非线性神经高斯-牛顿型内求解的一种失效模式:直接将神经RTM输出与FWI梯度匹配会产生目标空间不匹配,无法生成可靠的下降方向。这些结果表明,仅正向预测RTM图像不足以实现学习型预条件;准确的学习导数以及神经算子与目标一致的使用,对于生成有用的反演更新至关重要。

英文摘要:

Full-waveform inversion (FWI) is a powerful approach for reconstructing subsurface velocity models, but its practical performance is limited by ill-conditioning, sensitivity to the update direction, and the high cost of curvature-based methods. In this project, we investigate whether a neural operator trained on reverse-time-migration (RTM) images can provide a useful learned preconditioner for FWI. We compare projected FWI against neural-preconditioned FWI using either a standard Fourier neural operator (FNO) or a Jacobian-informed FNO (JI-FNO). The neural preconditioner applies the normal operator of the learned RTM map to modify the true Devito FWI gradient. Our experiments show that the JI-FNO preconditioner achieves the lowest model error while maintaining data-residual decay comparable to baseline projected FWI. In contrast, the standard FNO preconditioner is unstable and gives worse model recovery, despite using the same neural-preconditioning framework. We also identify a failure mode of a nonlinear neural Gauss Newton-type inner solve: directly matching the neural RTM output to the FWI gradient creates an objective-space mismatch and does not yield a reliable descent direction. These results suggest that forward RTM-image prediction alone is insufficient for learned preconditioning; accurate learned derivatives and objective-consistent use of the neural operator are critical for producing useful inversion updates.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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