arXiv:2410.15274physics.geo-phcs.LG2024-10被引 3

用物理约束的深度无监督学习,更准地反演地磁测深数据。

Physically Guided Deep Unsupervised Inversion for 1D Magnetotelluric Models

  • 通过可微分正演模型引导优化,无需标注数据。
  • 在不同频率下测试,反演电阻率模型精度更高。
  • 适合缺乏标注数据的地质勘探场景。

非常规能源如地热能和白氢的需求日益增长,亟需精准刻画地下结构并识别潜在储层。地磁测深(MT)方法能提供数百至数千米深度范围内的地下电阻率分布信息,对这一任务至关重要。然而传统迭代反演方法依赖大量参数调优,耗时且繁琐。近年虽有深度学习用于MT反演,但多基于有监督学习,需大规模标注数据集。本文利用TensorFlow构建可微分的正向MT算子,借助其自动微分能力,提出一种新的物理引导深度无监督反演算法,直接估计1维MT模型。不同于传统方法,该方法不依赖观测数据与对应模型的标注对,而是通过可微分建模算子物理引导目标函数最小化,仅需观测数据即可优化网络权重以降低数据拟合误差。实验在野外与合成数据上进行,覆盖不同采集频率,结果表明该方法获得的电阻率模型比现有技术更准确。

原文摘要 · Abstract (English)

The global demand for unconventional energy sources such as geothermal energy and white hydrogen requires new exploration techniques for precise subsurface structure characterization and potential reservoir identification. The Magnetotelluric (MT) method is crucial for these tasks, providing critical information on the distribution of subsurface electrical resistivity at depths ranging from hundreds to thousands of meters. However, traditional iterative algorithm-based inversion methods require the adjustment of multiple parameters, demanding time-consuming and exhaustive tuning processes to achieve proper cost function minimization. Recent advances have incorporated deep learning algorithms for MT inversion, primarily based on supervised learning, and large labeled datasets are needed for training. This work utilizes TensorFlow operations to create a differentiable forward MT operator, leveraging its automatic differentiation capability. Moreover, instead of solving for the subsurface model directly, as classical algorithms perform, this paper presents a new deep unsupervised inversion algorithm guided by physics to estimate 1D MT models. Instead of using datasets with the observed data and their respective model as labels during training, our method employs a differentiable modeling operator that physically guides the cost function minimization, making the proposed method solely dependent on observed data. Therefore, the optimization algorithm updates the network weights to minimize the data misfit. We test the proposed method with field and synthetic data at different acquisition frequencies, demonstrating that the resistivity models obtained are more accurate than those calculated using other techniques.

地磁测深深度学习无监督学习电阻率反演

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