用井下密度数据约束深度网络,提升重力反演精度与地质一致性。
Enhanced 3D Gravity Inversion Using ResU-Net with Density Logging Constraints: A Dual-Phase Training Approach
- 分两阶段训练:先预训练大网络,再用测井数据微调优化
- 合成模型与比绍普模型测试中,数据拟合误差显著降低
- 适合需要融合地质实测数据的重力反演任务
重力勘探因成本低、效率高成为重要地球物理方法。随着人工智能发展,基于深度学习(DL)的数据驱动反演方法具备传统正则化方法所不具备的物理属性恢复能力。然而现有深度学习方法缺乏先验信息约束,导致反演模型数据拟合误差大、结果不可靠,且未与其它勘探方法匹配,可能违背已知地质条件。本文提出一种新方法,融合井下密度测井信息以解决上述问题。首先,在神经网络中引入深度加权函数,并在加权密度参数域训练网络,使网络在加权正演算子约束下表现更优,反演模型数据拟合误差更小。其次,将网络训练分为两个阶段:先训练大型预训练网络Net-I,再利用测井数据作为约束进行微调,得到优化后的Net-II。在合成模型和比绍普模型上的测试与对比表明,本方法反演质量显著优于无约束的数据驱动深度学习反演方法。此外,还与传统聚焦反演(FI)及其测井约束变体进行了比较分析。最后,将该方法应用于墨西哥圣尼古拉斯矿区实测数据,与两种近期基于深度学习的重力反演方法进行对比分析。
原文摘要 · Abstract (English)
Gravity exploration has become an important geophysical method due to its low cost and high efficiency. With the rise of artificial intelligence, data-driven gravity inversion methods based on deep learning (DL) possess physical property recovery capabilities that conventional regularization methods lack. However, existing DL methods suffer from insufficient prior information constraints, which leads to inversion models with large data fitting errors and unreliable results. Moreover, the inversion results lack constraints and matching from other exploration methods, leading to results that may contradict known geological conditions. In this study, we propose a novel approach that integrates prior density well logging information to address the above issues. First, we introduce a depth weighting function to the neural network (NN) and train it in the weighted density parameter domain. The NN, under the constraint of the weighted forward operator, demonstrates improved inversion performance, with the resulting inversion model exhibiting smaller data fitting errors. Next, we divide the entire network training into two phases: first training a large pre-trained network Net-I, and then using the density logging information as the constraint to get the optimized fine-tuning network Net-II. Through testing and comparison in synthetic models and Bishop Model, the inversion quality of our method has significantly improved compared to the unconstrained data-driven DL inversion method. Additionally, we also conduct a comparison and discussion between our method and both the conventional focusing inversion (FI) method and its well logging constrained variant. Finally, we apply this method to the measured data from the San Nicolas mining area in Mexico, comparing and analyzing it with two recent gravity inversion methods based on DL.
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