Romain Le Goc

Romain Le Goc
Itasca Consultants SAS · Fractory

Ph. D.
Discrete Fracture Networks: design, modelling and simulations

About

51
Publications
15,567
Reads
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628
Citations
Citations since 2016
20 Research Items
485 Citations
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
Introduction
Romain Le Goc currently works at Itasca Consultants SAS. Romain does research in Mechanics, Geophysics and Geology. Their current projects are 'Advances in DFN modelling', 'Flow and Mechanical characterization of fractured rocks' and 'HM rock mass behavior characterization'.
Additional affiliations
April 2018 - present
Itasca Consultants SAS
Position
  • Engineer
Description
  • I'm involved in the "Factory", a joint laboratory between ITASCA and Géosciences Rennes, busy with the development of new ideas, methods, codes and software for discrete fracture network applications.
January 2010 - present
Itasca Consultant SAS
Position
  • Engineer
Description
  • Working on many discrete fracture network applications, including software development and data analyses.
March 2006 - December 2009
Université de Rennes 1
Position
  • PhD Student
Description
  • My Ph. D. focused on the inverse problem in hydrogeology, i.e. determining the main flow structures from observations.
Education
January 2007 - December 2009
Université de Rennes 1
Field of study
  • Hydrogeology
September 2000 - June 2005

Publications

Publications (51)
Article
Full-text available
A surrogate model is an engineering method to predict the outcome of some process rather than model the real process itself. Here, we use surrogate models based on the machine learning that have been trained using a synthetic data set generated by a numerical model. The concept of a surrogate model is a powerful link between the traditional paradig...
Conference Paper
The United States and countries around the world face an increasing demand for energy at the same time that carbon emissions and other environmental issues are facing greater scrutiny. Geothermal energy, generating electricity using the temperature difference between the surface and the sub-surface, is an active topic of research by the US Departme...
Conference Paper
Full-text available
Modeling heat transfer in complex heterogeneous fractured system is key for geothermal energy applications. Discrete fracture network (DFN) modeling is the ideal framework to reproduce the advective part of the transport, which is determined by the fracture connectivity and heterogeneity. This approach in general sacrifices the representation of th...
Conference Paper
Full-text available
evaluate the use of graphs as a fast and relevant substitute to DFNs. Graphs reduce the DFNs’ complexity to their connectivity structure by forming an assembly of nodes connected by edges, to which physical properties, like a conductance, can be assigned. Both the graph architecture (either fracture- or intersection- based) and the edge conductance...
Technical Report
The objective is to significantly reduce the rock mass mechanical modeling uncertainties, which are above all related to the geometrical and mechanical properties of the fracture network, especially relative to scaling and anisotropy issues. It is also to better address, in the numerical models, the issues raised by the complex nature of the rock f...
Conference Paper
A surrogate model is a machine learning model that has been trained using a synthetic data set generated by a numerical model. The concept of a surrogate model is a powerful link between the traditional paradigm of numerical modeling and the new paradigm of machine learning. Surrogate models are fast and can accurately predict a set of outputs of a...
Poster
Full-text available
DFN.lab is a modular computational suite to deal with three-dimensional discrete fracture networks (DFN) models from DFN generation to simulation and analysis of connectivity, flow, mechanical and transport properties. DFN.lab is developed by the Fractory, a joint laboratory between the French institute for scientific research (CNRS), the universit...
Article
Full-text available
This paper presents analytical solutions to estimate at any scale the fracture density variability associated to stochastic Discrete Fracture Networks. These analytical solutions are based upon the assumption that each fracture in the network is an independent event. Analytical solutions are developed for any kind of fracture density indicators. Th...
Poster
In crystalline rocks, flow takes place within the network of open fractures. Predicting flow paths is a basic requirement for groundwater management or environmental risk assessment. A major issue is that a large amount of fractures (up to 80%) is completely sealed by mineral precipitations and rock weathering with potentially important consequence...
Technical Report
Full-text available
Olkiluoto Island, which is located in SW Finland, has been selected as the site for a deep geological repository for the high-level spent nuclear fuel generated by the nuclear power plants operated by the Finnish power companies TVO and Fortum. On behalf TVO and Fortum, Posiva has continued updating the multidisciplinary site description, toward t...
Conference Paper
We start this presentation by assuming that a model and a mesh of the DFNs have been computed. We focus here on the numerical methods to solve efficiently single-phase flow problems.We will present the software NEF-Flow dedicated to solving single phase flow in large scale DFNs. NEF stands for Numerical Experiments involving Fractures. The softwar...
Conference Paper
Full-text available
Fractures are key elements governing permeability and flow paths in crystalline rocks and sedimentary layers with low matrix porosity. The ability to properly predict those properties, which is crucial for some industrial applications, such as the risk assessment in nuclear waste management, strongly relies on our ability to properly describe the f...
Article
Full-text available
We derive the relationships that link the general elastic properties of rock masses to the geometrical properties of fracture networks, with a special emphasis to the case of frictional crack surfaces. We extend the well‐known elastic solutions for free‐slipping cracks to fractures whose plane resistance is defined by an elastic fracture (shear) st...
Conference Paper
Full-text available
Rock mass mechanical properties are strongly controlled by the fractures they contain. Their determination raises strong issues for many rock-engineering applications, like underground repository safety assessment, support design, slope stability or mine caving. To compensate the impossibility to perform direct in-situ measures of these properties...
Conference Paper
Full-text available
Discrete Fracture Network – is primarily a modeling framework for fractured geological systems that aims to integrate field data into simulations of flow and/or deformation. It is complementary to, or competing with, continuum methods with both advantages of easily integrating the statistical properties of fracture networks, and of not assuming any...
Article
Full-text available
Fractures have a significant impact on rock mass mechanical and hydraulic properties, which is a concern for rock engineering applications like excavation or repository design, support design, slope stability and caving in mines. To address this issue, a sound description of the fracturing pattern is required. DFN models are statistical models whic...
Article
Full-text available
A major use of DFN models for industrial applications is to evaluate permeability and flow structure in hardrock aquifers from geological observations of fracture networks. The relationship between the statistical fracture density distributions and permeability has been extensively studied, but there has been little interest in the spatial structur...
Conference Paper
Full-text available
In a lot of geological environments, permeability is dominated by the existence of fractures and by their degree of interconnections. Models have shown that flow properties depends mainly on the statistical properties of the fracture population (length, apertures, orientation) and of intersections, on the topological properties of the network, as w...
Article
Full-text available
Fractures change mechanical properties of rock masses, which can be a concern for many rock-engineering applications like underground repository and support design, slope stability or mine caving. We propose to calculate, for typical hard rock conditions, the link between elastic properties and the complete fracture network system through its relev...
Conference Paper
Full-text available
Observations often display an intact rock strength decrease as specimen size increases. Existing attempts for reproducing this scale effect mainly rely on the introduction of defects as discrete cracks or veins. We propose a continuous approach where the rock micro-scale strength properties are spatially correlated. The correlation law is a correla...
Article
Full-text available
The topology of two discrete fracture network models is compared to investigate the impact of constrained fracture growth. In the Poissonian discrete fracture network model the fractures are assigned length, position and orientation independent of all other fractures, while in the mechanical discrete fracture network model the fractures grow and th...
Technical Report
Full-text available
The objective of the project is to provide a quantitative assessment of the scaling evolution, up to 100 m, of rock mass elastic effective properties for conditions relevant to the POSE niche surroundings at the Olkiluoto site. For that purpose a theoretical approach is developed. It is based a on statistical Discrete Fracture Network (DFN) descr...
Conference Paper
Full-text available
We discuss the parameters that control fracture density in the Earth, and relate the fracture density distributions to the growth processes that build up networks. By considering a basic three-stage process with nucleation, growth, and arrest, we find out that the fracture systems organize according to two main regimes. The smallest fractures can g...
Conference Paper
Full-text available
We perform site scale DFN modeling using a geometrical and quantitative approach. The DFN model is a statistical model which defines the density of fractures having given geometrical properties (size and orientation) and which includes an intrinsic variability term. The density variability term is defined from a scaling analysis. Density terms are...
Conference Paper
Full-text available
A major use of DFN for industrial applications is to evaluate permeabilities and flow structure in hard-rock aquifers from geological observations of fracture networks. The relationship between the statistical fracture density distributions and permeability has been extensively studied, but there has been little interest in the spatial structure of...
Conference Paper
Full-text available
Fractures have a significant impact on rock mass strength, which is a concern for rock engineering applications like excavation or repository design, support design, slope stability and caving in mines. Addressing this issue includes both the description of the fracturing pattern and the relationship between fracture characteristics and rock mass m...
Technical Report
Full-text available
Fracture networks arise from the combination between fundamental fracturing processes and in situ conditions like geological factors, stress history, major faults, depth/pressure or rock mass properties. Changes of these conditions throughout space or time likely induce spatial variations of the fracture network geometrical properties. But the frac...
Article
Full-text available
We propose a mapping from fracture systems consisting of intersecting fracture sheets in three dimensions to an abstract network consisting of nodes and links. This makes it possible to analyze fracture systems with the methods developed within modern network theory. We test the mapping for two-dimensional geological fracture outcrops and find that...
Article
Full-text available
In order to improve discrete fracture network (DFN) models, which are increasingly required into groundwater and rock mechanics applications, we propose a new DFN modeling based on the evolution of fracture network formation—nucleation, growth, and arrest—with simplified mechanical rules. The central idea of the model relies on the mechanical role...
Conference Paper
Fractures in rock masses strongly influence the underground mechanical and hydrogeological behavior. Understanding the relation between fracturing properties and rock properties is essential and still is a research area. In parallel, it is as much important to be able to characterize the fracturing properties into DFN models whose mean estimates an...
Conference Paper
Full-text available
We discuss the parameters that control fracture density on the Earth. We argue that most of fracture systems are spatially organized according to two main regimes. The smallest fractures can grow independently of each others, defining a "dilute" regime controlled by nuclei occurrence rate and individual fracture growth law. Above a certain length,...
Article
Full-text available
We argue that most fracture systems are spatially organized according to two main regimes: a "dilute" regime for the smallest fractures, where they can grow independently of each other, and a "dense" regime for which the density distribution is controlled by the mechanical interactions between fractures. We derive a density distribution for the den...
Article
Full-text available
We present a methodology for identifying highly-localized flow channels embedded in a significantly less permeable medium using steady-state head and geometrical data. This situation is typical of fractured media where flows are often strongly channeled at the scales of interest (10 m–1 km). The objective is to identify both geometrical and hydraul...
Conference Paper
In a first step, we numerically assess the relevance of power-averaging as a means for permeability upscaling on a variety of 2D and 3D, dense and sparse and on-lattice and off-lattice structures. Power averaging consists in finding the most determinant moment of the permeability distribution for upscaling. The moment order is the power-average exp...
Article
Full-text available
We introduce two new channeling indicators Dic and Dcc based on the Lagrangian distribution of flow rates. On the basis of the participation ratio, these indicators characterize the extremes of both the flow-tube width distribution and the flow rate variation along flow lines. The participation ratio is an indicator biased toward the larger values...
Thesis
Full-text available
La gestion d'un aquifère repose sur l'étude de ses propriétés hydrauliques. Nous proposons une approche computationnelle afin de caractériser la structure physique d'un aquifère et les propriétés hydrauliques associées, en focalisant sur l'étude des milieux hétérogènes fracturés où les écoulements sont fortement chenalisés. Ainsi, une première part...
Technical Report
Full-text available
Investigations led for several years at Laxemar and Forsmark reveal the large heterogeneity of geological formations and associated fracturing. This project aims at reinforcing the statistical DFN modeling framework adapted to a site scale. This leads therefore to develop quantitative methods of characterization adapted to the nature of fracturing...
Conference Paper
In fractured media as well as in highly heterogeneous porous media, flow can be highly channeled in a very sparse network of channels. More than 80% of the flow can take place in less than 1% of the volume of the medium. Because of their sparsity, the channels cannot be identified by geophysical methods. Their localization relies on the interpretat...
Conference Paper
Natural fractured media are complex because of the large number of fractures of widely-scattered characteristics (length, transmissivity). Simulating hydraulic processes by accounting for the natural complexity requires flexible software and high performance computing. We develop a parallel fracture network software MPFRAC (for Massive Parallel FRA...

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Projects

Projects (5)
Project
ENIGMA is an Innovative Training Network funded by the European Commission (https://enigma-itn.eu/). The ENIGMA ITN ( European training Network for in situ imaGing of dynaMic processes in heterogeneous subsurfAce environments) aims at training a new generation of young researchers in the development of innovative methods for imaging process dynamics in subsurface hydrosystems, in order to enhance understanding and predictive modelling capacities and to transfer these innovations to the economic sector. The 15 young future PhD students will contribute to develop the spatial representation of subsurface heterogeneity, fluxes, chemical reactions and microbial activity, through the integration of data and approaches from geophysics, hydrology, soil physics, and biochemistry. The network ENIGMA gather 21 partners (15 academic and 6 industrial) from 8 European countries. Each of the 15 future PhD students will conduct the research work in 2 or 3 institutions, in collaboration with the industrial partners.