This paper reports on analyses of fluid exchange between fractures in the simulation of flow through fractured porous media. Flow in the porous media is modeled with traditional Darcy’s equations and the coupling between flow in the porous media and fractures is based on the conceptual Discrete-Fracture-Matrix (DFM) representation, where the fractures are idealized as lower-dimensional elements at the interface of matrix elements. The DFNMesh algorithm is adopted to generate the Finite Element meshes and a novel methodology to handle overlapping fractures in the context of Mixed Finite Element methods is explored. Flux approximation with H(div)-conforming spaces are adopted which are particularly appealing for this analysis because of its inherent properties such as local mass conservation and strong divergence-free enforcement for incompressible flows. The analyses are carried out using simple two-fracture domains and a benchmark problem with eight fractures.
Month: January 2026
Few-shot and continuous online learning for forecasting in the energy industry
Forecasting in the energy sector is critical for planning and efficiency, but existing methods require extensive historical data and struggle with changing conditions. This work presents a few-shot forecasting method for energy time series prediction under nonstationary conditions and data scarcity. The solution “plugs into” any existing regressor, combining ideas to create a flexible data-efficient tool. The model is continuously updated with two daily samples, a marked reduction compared to conventional batch-based training. This efficiency is guaranteed by a moving window, which prioritizes recent patterns and avoids machine learning drift. A normalization technique recalibrates cumulative sum forecasts by adjusting future targets relative to the latest observed series segment. This narrows the extrapolation range as new data arrives, aligning predictions with the updated training range. Complex architectures are not required when using the approach, as evidenced by an ablation study. The method surpassed algorithms like Time-series Dense Encoder and Neural Basis Expansion Analysis. Promising results were yielded on diverse datasets, including the Volve petroleum field, the UNISIM-II-H synthetic case, and the Open-Power-System-Data. Also, a longitudinal interpretability method is employed. This research aligns with the industry’s real needs, where data is limited and arrives in real-time streams.
Experimental Investigation of Polymer Degradation and Its Effects on Electrical Submersible Pump Operation
Challenges and suggestions for defining electrofacies models: The problem with well-log resolution and the resulting “shoulder bed effects” applied to a carbonate reservoir
Unravelling the origin of reworked deposits in Aptian lacustrine carbonate reservoirs of the Santos Basin, SE Brazil
The Barra Velha Formation, representing the uppermost Aptian formation of the Santos Basin, predominantly comprises dolomudstones, intraclastic grainstones, and rudstones. Additionally, spherulitic and Mg-rich claystones suggest deposition in a shallow alkaline lacustrine environment. Despite the significance of reworked deposits within the Barra Velha Formation, limited attention has been given to understanding their origin, provenance, and their link to high well productivity. This study aims to characterize the reworked carbonate facies and establish their diverse genesis using a multi-scale approach. Through the analysis of core samples retrieved from the upper 19 m of the Upper Barra Velha Formation, we identified eight sedimentary facies, including microfacies grouped into two distinct associations: back-barrier deposits and foreshore-shoreface transition deposits. Back-barrier deposits consist of shrubstones, laminated shrubby spherulitestone, laminated mudstone, massive grainstone, and massive rudstone facies, composed of in situ facies and carbonates reworked by wave and distal hyper-concentrated flow. Foreshore-shoreface transition deposits comprise laminated grainstone, pebble grainstone, and massive rudstone. The facies analyses provide insights into swash-backwash effects, hyper-concentrated flow, and high wave reworking deposits. Detailed interpretation of seismic reflectors in the Uppermost interval of Barra Velha Formation revealed two distinct geometric patterns: high-amplitude onlapping seismic reflectors toward the basement and bidirectional high-amplitude reflectors on the platform edge. These patterns primarily consist of spherulitestones, shrubstones, and grainstones-packstones BHI facies. Gravity flow deposits of a fan-delta in the Lowermost interval of the Barra Velha Formation were interpreted as rudstones-grainstones and mixed reworked carbonates/volcanic rocks BHI facies, associated with low-amplitude sheet-like shape reflectors dipping toward the slope seismic reflectors. Based on the constructed onlap curve derived from the seismic lines in the study area and the described facies associations, it is evident that the lake margins are expanding, conducive to the formation of reworked facies mainly associated with wave action.
Chapter Five – Extending h adaptivity with refinement patterns
This contribution introduces the idea of refinement patterns for the generation of optimal meshes in the context of the Finite Element Method. The main idea is to generate a library of possible patterns on which elements can be refined and use this library to inform an h adaptive code on how to handle complex refinements in regions of interest. There are no restrictions on the type of elements that can be refined, and the patterns can be generated for any element type. The main advantage of this approach is that it allows for the generation of optimal meshes in a systematic way where, even if a certain pattern is not available, it can easily be included through a simple text file with nodes and sub-elements. The contribution presents a detailed methodology for incorporating refinement patterns into h adaptive Finite Element Method codes and demonstrates the effectiveness of the approach through mesh refinement of problems with complex geometries.
DFNMesh: Finite element meshing for discrete fracture matrix models
This paper presents a novel methodology for robust Finite Element (FE) mesh generation of Discrete Fracture Matrix (DFM) models. The method can handle the complete multi-dimensional domain from the tridimensional porous rock matrix, through fracture surfaces, down to open curves for fracture–fracture intersections. The accompanying open-source code is written in modern C++ with a JSON interface and largely relies on two state-of-the-art FE libraries: NeoPZ and Gmsh. Starting from a user-defined coarse mesh, fractures are sequentially read as convex polygons and introduced without distortions to the coarse geometry. The main steps involve: intersect edges by checking for nodes on opposite sides of the fracture plane, extend intersections from edges to faces, coalesce intersections to closest existing nodes (given a tolerance), refine interface elements to conform to the fracture, identify subsets of fracture surface, mesh the surface, and locate boundaries and intersections where they arise. Finally, the space around fractures is filled with the fine-scale unstructured mesh, which is kept conformal. The robustness of the implementation is derived from the consistent background of well-defined and simple premises like convexity and side-specific element neighborhood. Results show that the proposed technique can construct adequate 3D DFM grids, while still giving users freedom to adjust between geometrical fidelity and mesh quality through more aggressive feature rejection.
Core scale investigation of fluid flow in the heterogeneous porous media based on X-ray computed tomography images: Upscaling and history matching approaches
In this paper, experiments and simulations were performed on outcrop samples from Lagoa Salgada in Rio de Janeiro, Brazil, as a possible analog to one of the most typical Brazilian Pre-salt carbonate reservoirs rocks. The rocks were microbial carbonates where plugs comprising two main facies were sampled, simplified as fine-grained and vugular facies. The plugs were utilized to study the impact of pore geometry with both experimental and simulation approaches on recovery factor, saturation profile, and relative permeability estimations. To provide direct visualization of the geometry, description of pore structure, and calculation of concentration profiles, computed tomography (CT) imaging was integrated with experimental measurements of petrography and core flooding. The injection of two pore volumes of formation water resulted in a recovery factor between 28 and 34 percent for the plug samples. Furthermore, based on porosity generated by dry and wet CT, as well as saturation profiles resulting from CT data collected during drainage and imbibition processes along the length of the plugs, it is revealed that the distribution of these properties was diverse and heterogeneous. An algorithm was used to process the 2D tomography images of the samples to remove the region related to the exterior parts. The images were then stacked to create a 3D fine-scale grid to simulate the porous media and the fluid flow by applying rules for the segmentation of rock types, porosity, and permeability estimations of each grid block. Course-scale grids were created by applying upscaling techniques to reduce computation time. Simulated produced fluid cuts for different upscaled models were compared with the experimental results from core flooding. A history-matching technique was then applied to match experimental and simulation results, calculating the relative permeability of two main defined facies and creating an updated model capable of assessing past and present performance and future forecasting. Since relative permeability is essential for accurate simulation, estimating these curves in the heterogeneous pre-salt reservoir considering different facies, greatly influences reasonable future prediction performance and the ability to make informed operational decisions.
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