Approaching geoscientific inverse problems with vector-to-image domain transfer networks

Details

Serval ID
serval:BIB_BEC9D136939E
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Approaching geoscientific inverse problems with vector-to-image domain transfer networks
Journal
Advances in Water Resources
Author(s)
Laloy Eric, Linde Niklas, Jacques Diederik
ISSN
0309-1708
Publication state
Published
Issued date
06/2021
Volume
152
Pages
103917
Language
english
Abstract
We present vec2pix, a deep neural network designed to predict categorical or continuous 2D subsurface property fields from one-dimensional measurement data (e.g., time series), thereby offering an alternative approach to solve inverse problems. The performance of the method is investigated through two types of synthetic inverse problems: (a) a crosshole ground penetrating radar (GPR) tomography experiment with GPR travel times being used to infer a 2D velocity field, and (2) a multi-well pumping experiment within an unconfined aquifer with time series of transient hydraulic heads being used to retrieve a 2D hydraulic conductivity field. For each type of problem, both a multi-Gaussian and a binary channelized subsurface domain with long-range connectivity are considered. Using a training set of 20,000 examples (implying as many forward model evaluations), the method is found to recover a 2D model that is in much closer agreement with the true model than the closest training model in the forward-simulated data space. Further testing with smaller training sample sizes shows only a moderate reduction in performance when using 5000 training examples only. Although these 5000 to 20,000 forward runs can be performed offline in parallel, the associated computational expense may still be prohibitive for very demanding forward solvers. In addition, re-training is required for each new measurement configuration. Even if the recovered models are visually close to the true ones, the data misfits associated with their forward responses are generally larger than the noise level used to contaminate the true data. Uncertainty of the inverse solution is partially assessed using deep ensembles, in which the network is trained repeatedly with random initialization. Overall, this study advances understanding of how to use deep learning to infer subsurface models from indirect measurement data. More work is needed to evaluate the suitability of our proposed approach for real data, for which model errors and uncertainty in the geologic scenario will bring additional complexities.
Keywords
Water Science and Technology
Create date
03/08/2021 21:48
Last modification date
04/08/2021 6:37
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