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Marcus Saraiva

Publications and source records attributed to Marcus Saraiva.

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Synthetic Well Log Generation with Preserved Multivariate Correlations and Vertical Facies Stacking Patterns

We present a novel procedure for generating synthetic well logs that simultaneously preserves multivariate correlations among petrophysical properties (Density, P-Sonic, S-Sonic) and vertical stacking patterns of electrofacies. The methodology integrates Markov chain models, autoencoder-based dimensionality reduction, and Markov chain Monte Carlo (MCMC) sampling in latent space. Application to a real turbidite reservoir dataset demonstrates that the framework successfully sustains fundamental rock physics relationships and generates geologically realistic vertical heterogeneity consistent with actual well log measurements. This technique addresses critical data scarcity in machine learning applications for seismic interpretation while enabling credible synthetic seismogram generation for scenario testing and uncertainty quantification in petroleum exploration and field development.

physics.geo-ph

Geophysics-informed neural network for model-based seismic inversion using surrogate point spread functions

Model-based seismic inversion is a key technique in reservoir characterization, but traditional methods face significant limitations, such as relying on 1D average stationary wavelets and assuming an unrealistic lateral resolution. To address these challenges, we propose a Geophysics-Informed Neural Network (GINN) that integrates deep learning with seismic modeling. This novel approach employs a Deep Convolutional Neural Network (DCNN) to simultaneously estimate Point Spread Functions (PSFs) and acoustic impedance (IP). PSFs are divided into zero-phase and residual components to ensure geophysical consistency and to capture fine details. We used synthetic data from the SEAM Phase I Earth Model to train the GINN for 100 epochs (approximately 20 minutes) using a 2D UNet architecture. The network's inputs include positional features and a low-frequency impedance (LF-IP) model. A self-supervised loss function combining Mean Squared Error (MSE) and Structural Similarity Index Measure (SSIM) was employed to ensure accurate results. The GINN demonstrated its ability to generate high-resolution IP and realistic PSFs, aligning with expected geological features. Unlike traditional 1D wavelets, the GINN produces PSFs with limited lateral resolution, reducing noise and improving accuracy. Future work will aim to refine the training process and validate the methodology with real seismic data.

physics.geo-ph