新方法无需已知震源,用深度先验提升地震反演精度
A new practical and effective source-independent full-waveform inversion with a velocity-distribution supported deep image prior: Applications to two real datasets
- 基于相关性设计无震源依赖目标函数,降低对初始模型和低频数据的依赖
- 在真实数据上成功实现反演,即使初始模型粗糙、缺少低频成分
- 结合深度图像先验重构速度场,显著减少非线性问题,适合实际地震勘探
全波形反演(FWI)是一种通过最小化观测与预测地震数据差异来高分辨率重建地下物理参数的先进方法。然而,传统FWI在实际应用中面临挑战,主要源于对数据误差的直接测量目标。准确估计震源子波、需要低频数据以及合理初值以避免周期跳跃是关键难题。此外,波动方程求解器在真实场景中常难以精确模拟观测数据的振幅。为此,本文提出一种基于相关性的无震源依赖目标函数,有效缓解震源不确定性和振幅依赖性,提升实际应用可行性。构建了基于该目标函数的深度学习框架,引入速度分布支持的深度图像先验,将速度反演重参数化为自编码器中的可训练参数,从而降低传统FWI目标函数的非线性。在基准速度模型的合成数据及两个真实数据集上验证了所提方法的优势。结果表明,即使在缺失低频数据、初始速度模型粗略、震源子波错误等挑战条件下,该方法仍具高效性与实用性。
原文摘要 · Abstract (English)
Full-waveform inversion (FWI) is an advanced technique for reconstructing high-resolution subsurface physical parameters by progressively minimizing the discrepancy between observed and predicted seismic data. However, conventional FWI encounters challenges in real data applications, primarily due to its conventional objective of direct measurements of the data misfit. Accurate estimation of the source wavelet is essential for effective data fitting, alongside the need for low-frequency data and a reasonable initial model to prevent cycle skipping. Additionally, wave equation solvers often struggle to accurately simulate the amplitude of observed data in real applications. To address these challenges, we introduce a correlation-based source-independent objective function for FWI that aims to mitigate source uncertainty and amplitude dependency, which effectively enhances its practicality for real data applications. We develop a deep-learning framework constrained by this new objective function with a velocity-distribution supported deep image prior, which reparameterizes velocity inversion into trainable parameters within an autoencoder, thereby reducing the nonlinearity in the conventional FWI's objective function. We demonstrate the superiority of our proposed method using synthetic data from benchmark velocity models and, more importantly, two real datasets. These examples highlight its effectiveness and practicality even under challenging conditions, such as missing low frequencies, a crude initial velocity model, and an incorrect source wavelet.
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