Speaker: Mariam Joundi
Date: Thursay 30th of January 2025, 1:15pm.
Abstract:
Dans le contexte de l'ambition climatique de l'Union Européenne visant la neutralité carbone à l'horizon 2050, l'hydrogène vert émerge comme un vecteur énergétique prometteur. Cette orientation stratégique nécessite l'élaboration de solutions innovantes pour le transport sécurisé de l'hydrogène (European Hydrogen Backbone, 2020). En France, une réorientation des infrastructures est envisagée, avec la proposition de réutiliser les réseaux de gaz existants pour le transport de l'hydrogène (GRTgaz, 2019). Cependant, cette substitution induit des modifications significatives des caractéristiques mécaniques des réseaux, augmentant ainsi leur vulnérabilité vis-à-vis les sollicitations externes (Boots et al., 2021). Dans le cadre d'une thèse, nous explorons l'interaction entre ces réseaux et les mouvements de terrain, dans le but de minimiser les risques associés.
Dans ce contexte, cette étude vise à développer un méta-modèle basé sur une modélisation numérique tridimensionnelle pour évaluer l'impact des affaissements de terrain sur les réseaux de gaz enterrés. Le méta-modèle développé cherche à quantifier le taux de transmission des affaissements de sol aux conduites, en fonction d’un coefficient de rigidité relative sol-conduite. Ce travail s'inscrit dans une démarche novatrice par son approche tridimensionnelle, offrant une perspective plus complète par rapport aux méta-modèles similaires développés dans la littérature, se reposant sur des modèles de base analytiques ou numériques (Joundi et al., 2023).
Une analyse numérique paramétrique, intégrant un total de 230 simulations par éléments finis (EF), a été développée, aboutissant à l'élaboration d'un premier méta-modèle. Ce méta-modèle établit une relation entre la courbure relative des pipelines et un coefficient de rigidité relative du système sol-pipeline, constituant ainsi une base robuste pour des évaluations probabilistes futures. Ce modèle a été comparé au méta-modèle de Wang et al. 2011 afin de positionner nos résultats dans le contexte des recherches existantes.
Des premières simulations de propagation d’incertitudes ont été menées pour évaluer la probabilité de défaillance des conduites exposées à un affaissement, aboutissant à l’établissement de premières courbes de vulnérabilité.
- Details
- Category: Seminar
Speaker: Bahaa Abou Chakra
Date: Thursday 19th of December 2024, 1:15pm.
Abstract:
Les argilites du Callovo-Oxfordien, en tant que barrières géologiques potentielles pour le stockage des déchets radioactifs en France, sont soumises à des sollicitations couplées, comme les variations de contraintes pendant l'excavation, les changements de saturation, les variations thermiques dues aux déchets exothermiques et des processus chimiques. Pour étudier la faisabilité du stockage géologique à court et long terme, des modèles couplés et des caractérisations expérimentales THMC (Thermo-Hydro-Mécanique-Chimique) doivent être développés. Cette étude évalue l'effet thermique sur le comportement mécanique de l'argilite du Callovo-Oxfordien à travers des essais triaxiaux, simulant les conditions de stockage in situ, avec différentes pressions de confinement et différentes orientations, parallèle et perpendiculaire au plan de litage. L'objectif aussi est de caractériser et quantifier les variations morphologiques et volumétriques des fissures, mesurées par tomographie 3D aux rayons X, pour évaluer l'impact de l'endommagement sur l'intégrité structurelle des échantillons.
- Details
- Category: Seminar
Speaker: Amandine Fratani
Date: Thursday 28th of November 2024, 1:15pm.
Abstract:
When creating a geological model from borehole data or 2D sections, the interpretation of 3D faults is often ambiguous and uncertain. This work focuses on the problem of associating partial fault observations, which has recently been formalized using a graph in which each fault observation is represented as a graph node, and graph edges carry the potential of pairwise associations. The likelihood of an association is computed using selected expert geological rules. However, fault observations are not pairwise independent, which prevents the consideration of higher-order effects such as the distribution of the throw or the length along several aligned nodes. To complement this approach, we propose a mathematical formalism for the use of high-order associations. The definition of expert rules in a multiple-point problem is challenging because of the very high dimensionality of the problem. To alleviate this, we propose to supplement expert rules by supervised machine learning using analog or incomplete interpretations. This work uses a Random Forest learner trained from a set of selected fault features computed from fault traces extracted from known 3D geological models (e.g., the length of the fault trace, the throw value, etc.). The association likelihood inference is formulated as a classification problem to determine the probability that fault observations belong to the same fault object based on the variables computed from the features of the k observations. To prevent overfitting, we propose to mimic a partly interpreted case: we split the 3D domain in two disjoint, spatially contiguous sectors A and B, and use sector A as training and sector B for testing. Preliminary results demonstrate the ability of Random Forest to retrieve probabilities of triplets that complete the pairwise representation.
- Details
- Category: Seminar
Speaker: Pauline Collon
Date: Thursday 21tst of November 2024, 1:15pm.
Abstract:
L'activité minière a des conséquences évidentes sur les paysages et la stabilité des sols sus-jacents, mais aussi sur la qualité de l'eau du fait d'un phénomène nommé "Drainage Minier". Dans ce séminaire je reviendrais sur les travaux réalisés en 2000-2005 dans le cadre du GISOS pour caractériser le drainage minier neutre à l'oeuvre pour les mines de fer lorraines, en décrivant les moyens expérimentaux et numériques qui avaient alors été utilisés pour prédire l'évolution de la qualité de l'eau en sortie de bassin. Ces travaux servent aujourd'hui de "référence" méthodologique pour l'étude d'un autre drainage minier, celui de la mine de lignite de Gardanne (Marseille), sujet de la thèse de Bastien Morin (BRGM - GeoRessources/RING).
- Details
- Category: Seminar
Speaker: Marius Rapenne
Date: Thursday 14th of November 2024, 1:15pm.
Abstract:
Docker is an open-source platform as service that provide OS-level virtualization of packages to allow the distribution of software in containers. It allows for a quick and easy deployment of any application in isolation in different environment. The goal of this seminar is to provide a quick overview of virtualization and its uses, and then focus on docker, the creation of docker images and containers, through some exercise.
- Details
- Category: Seminar
Speaker: Mohammad Mahdi Rajabi
Date: Friday 8th of November 2024, 1:15pm.
Abstract:
To address common challenges in neural networks—such as large data requirements, poor generalization, overfitting, lack of transparency, and physically unrealistic outputs—incorporating physical intuition into different stages of neural network design has proven to be highly effective. This approach leverages the strengths of neural networks while ensuring their outputs adhere, fully or partially, to established physical laws. As a result, it improves the reliability, interpretability, and practicality of neural networks and can reduce the need for vast training datasets. This methodology is particularly useful for modeling physical systems, such as those in solid and fluid mechanics, as well as cyber-physical systems like smart grids and autonomous vehicles. With the increasing number of techniques and publications in this area, a clear and structured review of these methods has become essential. I will present an overview of current methods, terminology, and best practices for integrating physics into neural networks, providing a detailed classification of approaches including pre-training integration, in-training integration, and architecture-level embedding. I will also discuss the limitations of existing methods and highlight promising directions for future research.
- Details
- Category: Seminar
Speaker: Paul Baville
Date: Thursday 17th of October 2024, 1:15pm.
Abstract:
Computer-assisted multi-well correlation aims at computing a large set of possible stratigraphic correlation scenarios from the same input data. WeCo (an automated multi-well correlation software developed by the RING Team) uses an adapted version of the Dynamic Time Warping to classify the simulated realizations from the most likely (lowest correlation cost) to the less likely (highest correlation cost). This correlation cost is given by a cost function corresponding to a principle of correlation (e.g., lithostratigraphy, chronostratigraphy, etc.).
The aim of this project is to define a consistent metric to compare well correlations generated by WeCo, and to classify them according to other criteria than the correlation cost. Since a correlation can be represented by an directed acyclic graph, whose nodes represent marker associations and edges represent transitions between marker associations, this work aims at applying the Hausdorff distance to compare two graphs. In this work, the use of the Hausdorff distance to compare multiple well correlations helps us to identify clusters of well correlations which have different costs, and to differentiate two well correlations having the same correlation cost.
- Details
- Category: Seminar
Speaker: Géraldine Pichot
Date: Thursday 10th of October 2024, 1:15pm.
Abstract:
In underground environments, fractures are numerous and present at all scales (from cm to km), with very heterogeneous properties. The most commonly used model for fractured rocks is the Discrete Fracture Matrix (DFM) model, in which fractures are represented as structures of codimension 1 (Discrete Fracture Network - DFN). In this work, stochastic DFNs are generated with the software DFN.lab (https://github.com/FractoryLabcom/software). It enables the generation of cubic-meter fractured rocks. The objective is to simulate efficiently single-phase flow in large-scale fractured porous media.etc.).
My presentation will be divided into two parts. In the first part, I will present results on flow in fractured rocks such as granite rocks where flow only occurs in the fractures (the surrounding rock is impervious). These rocks are made up of millions of fractures and the meshing of this geometry is a challenge that we have taken up in recent years with the development of the MODFRAC software (https://team.inria.fr/serena/fr/research/software/modfrac/). I will then present the method we used to discretise the flow problem, the Hybrid High Order method, capable of supporting general elements. The problem is solved using a direct solver. The code we developed is called NEF++ (https://team.inria.fr/serena/fr/research/software/nefpp/). In the second part of my talk, I will present the recent results we have obtained on flow in fractured porous rocks. Due to the porosity of the rock, a 3D flow also occurs in the rock and this flow is
coupled to the 2D flow in the fractures. To discretise this problem, a mixed hybrid finite element is used. As the linear system may contain millions of unknowns, direct solvers are no longer an option due to the excessive RAM consumption and only iterative methods can be used. I will present several examples demonstrating the excellent performances obtained with GMRES preconditioned by HPDDM (https://petsc.org/main/manualpages/PC/PCHPDDM/).
- Details
- Category: Seminar
Speaker: Zvi Koren
Date: Thursday 3rd of October 2024, 1:15pm.
Abstract:
This presentation introduces EarthStudy 360, a novel, target-oriented, seismic-driven system designed to generate the full image-domain scattering wavefield, decomposed into the local angle domain (LAD) coordinate system. This comprehensive image dataset serves as input for several key subsurface applications:
• High-definition subsurface model parameters: Utilizing full-azimuth reflection angle image data.
• High-resolution imaging: Enhancing structural and stratigraphic interpretation and reservoir characterization through directional (dip/azimuth) angle image data.
• Target markets: Addressing all subsurface imaging and interpretationhis correlation cost is given by a cost function corresponding to a principle of correlation (e.g., lithostratigraphy, chronostratigraphy, etc.).
EarthStudy 360 provides depth imaging processing experts and interpretation specialists with a complete set of image data, including accurate subsurface velocity models, structural attributes, medium properties, and reservoir characteristics. The rich information from all angles and azimuths ensures more reliable analysis and significantly reduces uncertainty. For instance, fracture analysis components offer precise information about fracture stress and orientation, which is crucial for optimizing drilling and achieving superior production rates.
In this presentation, I will describe the EarthStudy 360 seismic migration process in the local angle domain (LAD), the output, full-azimuth directional and opening-angle, common image gathers/volumes, and the corresponding applications for kinematic/dynamic parameter analyses and directional-based imaging (diffraction imaging). The system’s advantages will be demonstrated through numerous worldwide field examples.
- Details
- Category: Seminar