用生成模型反演河流沉积物,提升地质决策效率
Towards geological inference with process-based and deep generative modeling, part 2: inversion of fluvial deposits and latent-space disentanglement
- 用生成对抗网络模拟河流沉积结构,实现地质建模
- 4~20口井数据下反演失败,因潜在空间特征纠缠
- 微调潜空间可改善反演效果,适合地质建模应用
地下决策因数据获取成本高、不确定性大而困难,难以规模化获取新数据。将地质知识直接嵌入预测模型是一种有效替代方案。本研究提出联合方法:基于地质过程的模拟模型可用于训练生成模型,使其预测更高效。重点探索生成对抗网络(GAN)在生成河流沉积物后,能否通过反演匹配实际井数据与地震数据。针对包含4、8和20口井的三个测试样本,四种反演方法均表现不佳,尤其当井数增多或测试样本偏离训练数据时。核心瓶颈在于GAN的潜在表示存在特征纠缠,具有相似沉积特征的样本在潜在空间中未必接近。标签条件化或潜在空间过参数化可在训练阶段部分解耦潜在空间,但仍未充分支持成功反演。通过微调局部重构潜在空间,所有测试案例(含/不含地震数据)的匹配误差降至可接受水平。但该方法依赖初始部分成功的反演步骤,影响最终样本的质量与多样性。总体而言,当前GAN已具备集成至地质建模工作流的能力,仍需进一步评估其鲁棒性及最佳使用方式。
原文摘要 · Abstract (English)
High costs and uncertainties make subsurface decision-making challenging, as acquiring new data is rarely scalable. Embedding geological knowledge directly into predictive models offers a valuable alternative. A joint approach enables just that: process-based models that mimic geological processes can help train generative models that make predictions more efficiently. This study explores whether a generative adversarial network (GAN) - a type of deep-learning algorithm for generative modeling - trained to produce fluvial deposits can be inverted to match well and seismic data. Four inversion approaches applied to three test samples with 4, 8, and 20 wells struggled to match these well data, especially as the well number increased or as the test sample diverged from the training data. The key bottleneck lies in the GAN's latent representation: it is entangled, so samples with similar sedimentological features are not necessarily close in the latent space. Label conditioning or latent overparameterization can partially disentangle the latent space during training, although not yet sufficiently for a successful inversion. Fine-tuning the GAN to restructure the latent space locally reduces mismatches to acceptable levels for all test cases, with and without seismic data. But this approach depends on an initial, partially successful inversion step, which influences the quality and diversity of the final samples. Overall, GANs can already handle the tasks required for their integration into geomodeling workflows. We still need to further assess their robustness, and how to best leverage them in support of geological interpretation.
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