Inversion of 1D frequency- and time-domain electromagnetic data with convolutional neural networks
This method enables real-time subsurface resistivity estimation in exploration scenarios, offering a faster alternative to traditional optimization or probabilistic methods, though it is incremental as it applies existing neural network techniques to a specific domain.
The authors tackled the problem of electromagnetic data inversion in geophysics, which is prone to local minima or high computational costs, by using deep convolutional neural networks for 1D inversion of marine and onshore data, achieving accurate results on synthetic and real data instantaneously and providing uncertainty insights.
Inversion of electromagnetic data finds applications in many areas of geophysics. The inverse problem is commonly solved with either deterministic optimization methods (such as the nonlinear conjugate gradient or Gauss-Newton) which are prone to getting trapped in a local minimum, or probabilistic methods which are very computationally demanding. A recently emerging alternative is to employ deep neural networks for predicting subsurface model properties from measured data. This approach is entirely data-driven, does not employ traditional gradient-based techniques and provides a guess to the model instantaneously. In this study, we apply deep convolutional neural networks for 1D inversion of marine frequency-domain controlled-source electromagnetic (CSEM) data as well as onshore time-domain electromagnetic (TEM) data. Our approach yields accurate results both on synthetic and real data and provides them instantaneously. Using several networks and combining their outputs from various training epochs can also provide insights into the uncertainty distribution, which is found to be higher in the regions where resistivity anomalies are present. The proposed method opens up possibilities to estimate the subsurface resistivity distribution in exploration scenarios in real time.