53 results on '"Richard Giot"'
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2. Mécanique des roches - Caractérisation physique et mécanique des roches
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Richard GIOT, Stephen HÉDAN, and Philippe COSENZA
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Linguistics and Language ,Histology ,Mechanical Engineering ,General Chemical Engineering ,General Mathematics ,Organic Chemistry ,Metals and Alloys ,General Engineering ,General Physics and Astronomy ,General Chemistry ,General Medicine ,Condensed Matter Physics ,Biochemistry ,Industrial and Manufacturing Engineering ,Language and Linguistics ,Analytical Chemistry ,General Energy ,Oncology ,Materials Chemistry ,Physical and Theoretical Chemistry ,General Pharmacology, Toxicology and Pharmaceutics ,General Agricultural and Biological Sciences ,Spectroscopy - Published
- 2023
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3. Mécanique des roches - Caractérisation des massifs rocheux
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Richard GIOT, Stephen HÉDAN, and Philippe COSENZA
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Radiation ,Fuel Technology ,General Chemical Engineering ,Applied Mathematics ,General Earth and Planetary Sciences ,Energy Engineering and Power Technology ,General Materials Science ,Development ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Analysis ,Electronic, Optical and Magnetic Materials - Published
- 2023
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4. A fractional differential scheme for the effective transport properties of multiscale reactive porous media: Applications to clayey geomaterials
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Richard Giot, Philippe Cosenza, Albert Giraud, and Stephen Hedan
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Materials science ,Mechanics of Materials ,Electrical resistivity and conductivity ,Scheme (mathematics) ,Computational Mechanics ,General Materials Science ,Mechanics ,Fractional differential ,Geotechnical Engineering and Engineering Geology ,Porous medium - Published
- 2021
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5. Elastic moduli of clay minerals and their aggregates: A review
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Philippe Cosenza, Richard Giot, and Stephen Hedan
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Geochemistry and Petrology ,Geology - Published
- 2023
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6. Hydro-mechanical numerical modelling of the opening and closing of desiccation cracks in clayey rock
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Philippe Cosenza, Richard Giot, and Stephen Hedan
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Digital image correlation ,Environmental Engineering ,0211 other engineering and technologies ,Front (oceanography) ,02 engineering and technology ,021105 building & construction ,Relative humidity ,Geotechnical engineering ,Optical metrology ,Closing (morphology) ,Desiccation ,Geology ,021101 geological & geomatics engineering ,Civil and Structural Engineering - Abstract
The monitoring during one year of a gallery front of the Tournemire experimental station by optical metrology showed the presence of desiccation cracks sensitive to relative humidity variations in ...
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- 2020
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7. Integration of Transverse Isotropy in the Instantaneous Behaviour of Geomaterials with Application to Numerical Modelling of Underground Structures
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Sam Cuvilliez, François Laigle, Simon Raude, Roméo Fernandes, Inès Djouadi, and Richard Giot
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Hydrogeology ,Basis (linear algebra) ,Computer science ,Plane (geometry) ,business.industry ,Isotropy ,Constitutive equation ,0211 other engineering and technologies ,Soil Science ,Geology ,02 engineering and technology ,Structural engineering ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Transverse isotropy ,Architecture ,Tensor ,Anisotropy ,business ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences - Abstract
The paper deals with the integration of structural anisotropy in a pre-existing constitutive law for rocks, dedicated to the numerical modelling of underground structures. On the basis of bibliographic study, two approaches were selected and applied to a simple constitutive law to begin with, namely the Drucker–Prager model. The two appraoches considered are the fabric tensor approach and the weakness plane approach. Both approaches are described, the equations are provided and the resulting anisotropic models are implemented in the open source finite element software (Code_Aster in EDF R&D code general pour l’etude du comportement mecanique des structures diffuse sous licence GNU GPL, 2017). The models are then applied to the simplified numerical modelling of an underground facility and the main results are provided. The main advantages and drawbacks of both approaches are highlighted. The main findings of this work is that the fabric tensor approach is the most fitted for the material considered for the future prospects. The future prospects are the integration of anisotropy in a much more complex isotropic model being developed by EDF research team for application to geomaterials.
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- 2020
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8. Experimental and numerical analysis of in situ pull-out tests on rock bolts in claystones
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Richard Giot, Christophe Auvray, Simon Raude, and Albert Giraud
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In situ ,Rock bolt ,Environmental Engineering ,Numerical analysis ,Grout ,0211 other engineering and technologies ,02 engineering and technology ,engineering.material ,021105 building & construction ,engineering ,Geotechnical engineering ,Strain gauge ,Geology ,021101 geological & geomatics engineering ,Civil and Structural Engineering - Abstract
In situ pull-out tests were performed in claystones at the Andra Underground Research Laboratory of Meuse/Haute-Marne on fully grouted bolts. The bolts were instrumented with strain gauges along th...
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- 2019
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9. Behavior in mixed-mode of desiccation cracks on a clayey rock front gallery
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Stephen Hedan, Valéry Valle, Richard Giot, and Philippe Cosenza
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Geotechnical Engineering and Engineering Geology - Published
- 2022
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10. 3D coupled HM–XFEM modeling with cohesive zone model and applications to non planar hydraulic fracture propagation and multiple hydraulic fractures interference
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P. Massin, Alexandre Martin, Maxime Faivre, Daniele Colombo, Bertrand Paul, Richard Giot, Fabrice Golfier, Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), IFP Energies nouvelles (IFPEN), ANR-17-CE06-0016,HydroGeoDam,Vers une meilleure évaluation de l'impact de l'endommagement hydraulique pour les applications de géo-ingénierie(2017), ANR-10-LABX-0021,RESSOURCES21,Strategic metal resources of the 21st century(2010), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), and Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS)
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fracture spacing ,cohesive zone model ,fracture interference ,Poromechanics ,0211 other engineering and technologies ,Computational Mechanics ,General Physics and Astronomy ,02 engineering and technology ,X-FEM ,[SPI.MECA.SOLID]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Solid mechanics [physics.class-ph] ,01 natural sciences ,Physics::Geophysics ,Physics::Fluid Dynamics ,hydro-mechanical coupling ,Discontinuity (geotechnical engineering) ,Fluid dynamics ,0101 mathematics ,fluid-driven fracture ,021101 geological & geomatics engineering ,Extended finite element method ,complex fracture ,Biot number ,Mechanical Engineering ,Mechanics ,Computer Science Applications ,010101 applied mathematics ,Cohesive zone model ,Mechanics of Materials ,Lubrication ,Porous medium ,Geology - Abstract
A 3D fully coupled hydromechanical model for the simulation of fluid-driven fracture propagation through poroelastic saturated media is presented and compared to several analytical or numerical benchmarks. The hydromechanical coupling in the porous matrix is derived within the framework of the generalized Biot theory and the fluid flow in the fractures satisfies the lubrication equation. The presence and propagation of fluid-driven fractures is handled with the extended finite element method and the propagation of the fluid-driven fractures is governed by a mixed linear cohesive law relying on a stable mortar formalism. A comparison between numerical results and a semi-analytical solution for plane fluid-driven fractures in porous media assess the validity of the proposed model. Then, a procedure for the propagation of fluid-driven fractures on non predefined paths is detailed. In particular, the fracture reorientation angle is computed exclusively from cohesive quantities. Various numerical experiments are performed to study the interferences between neighboring fluid-driven fractures as well as the reorientation of fluid-driven fractures under complex stress conditions. Finally, the model is extended to discontinuity junctions and an application to arrays of vertical fractures initiated from horizontal wells is presented.
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- 2018
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11. Multi-stage water permeability measurements on claystone by steady and transient flow methods
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Nathalie Conil, Rémi de La Vaissière, Christophe Auvray, and Richard Giot
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Materials science ,0211 other engineering and technologies ,Modulus ,Geology ,02 engineering and technology ,Mechanics ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Transient flow ,Multi stage ,Permeability (earth sciences) ,Permeability measurements ,Wetting ,Inverse method ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Biot coefficient - Abstract
The present paper deals with the comparison of permeability measurements between steady flow and transient flow tests (pulse decay test). We submitted one sample to a series of four sequences of one pulse test followed by one steady flow test. This whole multi-stage test lasted approximately 120 days. The pulse tests were interpreted with an inverse method proposed by Giot et al. (2011) allowing assessment of mechanical and poromechanical parameters in addition to intrinsic permeability. Overall, the pulse test measurements showed that the claystone progressively turned into mud, exhibiting constant decreases in permeability and Young's modulus and a constant increase in the Biot coefficient. In contrast, the steady flow tests exhibited constant permeability corresponding to the final value assessed by the pulse test. These results are explicated by the evolution of the claystone fabric with wetting and call into question the representativeness of permeability measurements by the steady flow method on these kinds of materials.
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- 2018
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12. Influence of stress induced microcracks on the tensile fracture behavior of rocks
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Richard Giot, Sourena Moosavi, Luc Scholtès, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), and Université de Poitiers-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
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Materials science ,Tensile fracture ,Stress induced ,0211 other engineering and technologies ,Modulus ,[CHIM.CATA]Chemical Sciences/Catalysis ,02 engineering and technology ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Strength of materials ,Computer Science Applications ,Brittleness ,Fracture toughness ,Ultimate tensile strength ,Composite material ,Anisotropy ,ComputingMilieux_MISCELLANEOUS ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences - Abstract
The study characterizes the influence of preferentially oriented microcracks on the tensile fracture behavior of rocks by means of a discrete modeling approach. A series of numerical experiments is performed so as to systematically evaluate the emergent properties of media containing microcracks swarms with predefined intensities and orientations. Emphasis is put on the apparent Young’s modulus, tensile strength and fracture toughness. Microcracks swarms reduce the strength of materials, affect their overall brittleness and induce anisotropic behavior. They also directly influence the initiation and propagation of mode I fractures which can deviate from their expected path as a result of branching.
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- 2018
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13. A transversely isotropic thermo-poroelastic model for claystone: parameter identification and application to a 3D underground structure
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Nadia Massoussi, Julie Huang, Maxime Faivre, Sylvie Granet, Richard Giot, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Mécanique des Structures Industrielles Durables (LAMSID - UMR 8193), EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire Navier (navier umr 8205), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D), and EDF (EDF)-EDF (EDF)
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biology ,Poromechanics ,Constitutive equation ,0211 other engineering and technologies ,Structure (category theory) ,02 engineering and technology ,Mechanics ,[CHIM.CATA]Chemical Sciences/Catalysis ,Physics::Classical Physics ,Geotechnical Engineering and Engineering Geology ,biology.organism_classification ,Physics::Geophysics ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Transverse isotropy ,Analytic solution ,Aster (genus) ,Finite element code ,Geology ,021101 geological & geomatics engineering - Abstract
International audience; A transversely isotropic thermo-poroelastic constitutive law is developed and implemented in the finite element code Code_Aster (EDF, France). It is then validated using an analytic solution for an inclined borehole in a transversely isotropic medium. A strategy for identifying the parameters of the transversely isotropic thermo-poroelastic model based on an inverse method is proposed on the basis of different laboratory tests. To demonstrate the efficiency and applicability of the model, it is then applied in a three-dimensional numerical model of an underground structure in a parameter sensitivity study. The results of the modelling highlight the importance of accounting for anisotropic phenomena when determining the dimensions of underground facilities. The whole approach is presented in the paper, from model development to application to 3D numerical modelling to an engineering case study.
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- 2018
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14. Self-sealing of claystone under X-ray nanotomography
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Christophe Auvray, Jean Talandier, Richard Giot, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Agence Nationale pour la Gestion des Déchets Radioactifs (ANDRA)
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0211 other engineering and technologies ,Mineralogy ,Geology ,Ocean Engineering ,02 engineering and technology ,[CHIM.CATA]Chemical Sciences/Catalysis ,010502 geochemistry & geophysics ,01 natural sciences ,X ray nanotomography ,ComputingMilieux_MISCELLANEOUS ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
International audience
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- 2018
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15. A unified thermoplastic/viscoplastic constitutive model for geomaterials
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Richard Giot, S. Raude, Roméo Fernandes, and F. Laigle
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chemistry.chemical_classification ,Thermoplastic ,Yield (engineering) ,Materials science ,Viscoplasticity ,Constitutive equation ,0211 other engineering and technologies ,02 engineering and technology ,Geotechnical Engineering and Engineering Geology ,020501 mining & metallurgy ,0205 materials engineering ,chemistry ,Creep ,Solid mechanics ,Earth and Planetary Sciences (miscellaneous) ,Geotechnical engineering ,Constant (mathematics) ,Triaxial compression ,021101 geological & geomatics engineering - Abstract
Research on the effect of temperature changes on the behaviour of geomaterials has become increasingly important in recent years. This growing interest is partially due to the recent development of high-level nuclear waste disposals. Because of the complex influence of temperature in these areas, it is necessary to understand the effects of temperature on rock-like materials and use the appropriate constitutive equations to numerically model these phenomena. In this paper, a thermoplastic/viscoplastic constitutive model is developed for this purpose. The model includes thermal softening, the evolution of the yield functions with temperature, and the effects of temperature on the time-dependent behaviour. The model performance is demonstrated by some simple test cases on Tournemire and Bure clayey rocks including triaxial compression tests and creep tests under constant temperatures. The numerical results are discussed using experimental data, which demonstrate that the model can reproduce the overall behaviour of this type of materials under deviatoric loads and non-isothermal conditions.
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- 2015
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16. An identification method to calibrate higher-order parameters in local second-gradient models
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Simon Raude, Alexandre Foucault, Roméo Fernandes, and Richard Giot
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Marketing ,Engineering ,business.industry ,Strategy and Management ,Numerical analysis ,Numerical models ,Laboratory scale ,Identification (information) ,Simple (abstract algebra) ,Media Technology ,Calculus ,Applied mathematics ,General Materials Science ,business - Abstract
A numerical method is presented for identifying the material parameters that appear in second-gradient models. For local second-gradient models, additional material parameters must be defined in numerical models. The objective of the present study is to develop a simple numerical identification procedure for these additional coefficients. The method combines modelling of laboratory tests with analytical implements. Numerical studies are then used to validate the method for a shale and to investigate the effects of both the internal length and the additional coefficients on the numerical responses. The procedure provides the first coherent results achieved at the laboratory scale.
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- 2015
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17. Integrated Inverse Method to Estimate Virgin Stress State in Reservoirs and Overburden
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Richard Giot, Pierre Thore, Marianne Conin, Yves M. Leroy, Antoine Mazuyer, Paul Cupillard, GeoRessources, and Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS)
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0209 industrial biotechnology ,Petroleum engineering ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,010401 analytical chemistry ,Mathematical analysis ,Borehole ,02 engineering and technology ,01 natural sciences ,Finite element method ,0104 chemical sciences ,Stress field ,Piecewise linear function ,Overburden ,020901 industrial engineering & automation ,Hydraulic fracturing ,Limit analysis ,Vertical direction ,ComputingMilieux_MISCELLANEOUS ,Geology - Abstract
Summary Stress estimation in reservoirs and overbuden has become a key point during the exploration and the exploitation of the oil ans gas fields. We propose in this abstract an integrated method to compute a physically admissible (i.e. satisfying the equilibrium equations) 3D stress field in whole geological models. Stress field is computed using a simple elastic behavior and it is constrained to the wellbore data using an inverse approach. Forward problem is solved using a Finite Element Analysis. The model parameters to invert are the Neumann conditions which are assumed to be piecewise linear functions along the vertical direction. The data parameters are stress observations which came from the hydraulic fracturing and the borehole breakouts. Misfit between the computed stress and the observed stress is minimized using the CMA-ES algorithm. The method is tested with a synthetic case by taking a stress field computed with the Limit Analysis method as reference. The inversion results show that the method is able to well retrieve the stress variation in the geological model.
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- 2017
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18. List of contributors
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Liang Chen, Zuorong Chen, Jean-Baptiste Colliat, Gilles Duveau, A. Ghassemi, Richard Giot, Albert Giraud, Bezalel C. Haimson, Paul Hauseux, Dawei Hu, Rob Jeffrey, Alexandre Lavrov, Xiaodong Ma, Moustafa Masri, Panos Papanastasiou, Emmanuel Roubin, John W. Rudnicki, Ernestos Sarris, Jianfu Shao, Wanqing Shen, Amir K. Shojaei, George Z. Voyiadjis, Shouyi Xie, Fan Zhang, Xi Zhang, Zhihong Zhao, and Hui Zhou
- Published
- 2017
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19. Stability, accuracy, and efficiency of numerical methods for coupled fluid flow in porous rocks
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Albert Giraud and Richard Giot
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Numerical analysis ,0211 other engineering and technologies ,02 engineering and technology ,Mechanics ,01 natural sciences ,010101 applied mathematics ,Partial saturation ,Crack initiation ,Fluid dynamics ,Geotechnical engineering ,0101 mathematics ,Porosity ,Anisotropy ,Saturation (chemistry) ,Geology ,021101 geological & geomatics engineering ,Extended finite element method - Abstract
In this chapter, numerical methods for modeling of fluid-driven cracks in rocks are presented. The modeling of the coupled fluid flow in continuous media is first reminded, with presentation of several applications. Then the modeling of the fractured rock is considered. A review of the most common methods for coupled fluid flow in fractured porous rocks is presented and the manuscript focuses on the extended finite element method (XFEM) method combined with hydromechanical couplings. Several problems in relation with fluid-driven crack in porous rocks are foreseen, such as partial saturation, anisotropy, or crack initiation. Some details about numerical issues are also given.
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- 2017
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20. Thermo-hydro-mechanical modeling with Langmuir's adsorption isotherm of the CO2 injection in coal
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Dragan Grgic, Kanssoune Saliya, Albert Giraud, and Richard Giot
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Langmuir ,Bulk modulus ,Materials science ,Biot number ,business.industry ,020209 energy ,technology, industry, and agriculture ,Computational Mechanics ,Thermodynamics ,02 engineering and technology ,Geotechnical Engineering and Engineering Geology ,7. Clean energy ,Adsorption ,020401 chemical engineering ,13. Climate action ,Mechanics of Materials ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Coal ,Geotechnical engineering ,0204 chemical engineering ,Rock mass classification ,business ,Porosity ,Dissolution - Abstract
In this paper, we used a theoretical model for the variation of Eulerian porosity, which takes into account the adsorption process known to be the main mechanism of production or sequestration of gas in many reservoir of coal. This process is classically modeled using Langmuir's isotherm. After implementation in Code_Aster, a fully coupled thermo-hydro-mechanical analysis code for structures calculations, we used numerical simulations to investigate the influence of coal's hydro-mechanical properties (Biot's coefficient, bulk modulus), Langmuir's adsorption parameters, and the initial liquid pressure in rock mass during CO2 injection in coal. These simulations showed that the increase in the values of Langmuir's parameters and Biot's coefficient promotes a reduction in porosity because of the adsorption process when the gas pressure increases. Low values of bulk modulus increase the positive effect (i.e., increase) of hydro-mechanical coupling on the porosity evolution. The presence of high initial liquid pressure in the rock mass prevents the progression of injected gas pressure when CO2 dissolution in water is taken into account.
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- 2014
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21. Experimental observations of mechanical dilation at the onset of gas flow in Callovo-Oxfordian claystone
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Jon F. Harrington, Robert J. Cuss, Christophe Auvray, and Richard Giot
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Dilatant ,Flow (psychology) ,Geology ,Ocean Engineering ,Dilation (morphology) ,Outflow ,Geotechnical engineering ,Stage (hydrology) ,Diffusion (business) ,Petrology ,Porosity ,Radial stress ,Water Science and Technology - Abstract
Understanding the mechanisms controlling the advective movement of gas and its potential impact on a geological disposal facility (GDF) for radioactive waste is important to performance assessment. In a clay-based GDF, four primary phenomenological models can be defined to describe gas flow: (i) diffusion and/or solution within interstitial water; (ii) visco-capillary (or two-phase) flow in the original porosity of the fabric; (iii) flow along localized dilatant pathways (micro-fissuring); and (iv) gas fracturing of the rock. To investigate which mechanism(s) control the movement of gas, two independent experimental studies on Callovo-Oxfordian claystone (COx) have been undertaken at the British Geological Survey (BGS) and LAEGO–ENSG Nancy (LAEGO). The study conducted at BGS used a triaxial apparatus specifically designed to resolve very small volumetric (axial and radial) strains potentially associated with the onset of gas flow. The LAEGO study utilized a triaxial setup with axial and radial strains measured by strain gauges glued to the sample. Both studies were conducted on COx at in situ stresses representative of the Bure Underground Research Laboratory (URL), with flux and pressure of gas and water carefully monitored throughout long-duration experiments. A four-stage model has been postulated to explain the experimental results. Stage 1: gas enters at the gas entry pressure. Gas propagation is along dilatant pathways that exploit the pore network of the material. Around each pathway the fabric compresses, which may lead to localized movement of water away from the pathways. Stage 2: the dendriticflow path network has reached the mid-plane of the sample, resulting in acceleration of the observed radial strain. During this stage, outflow from the sample also develops. Stage 3: gas has reached the backpressure end of the sample with end-to-end movement of gas. Dilation continues, indicating that gas pathway numbers have increased. Stage 4: gas-fracturing occurs with a significant tensile fracture forming, resulting in failure of the sample. Both studies clearly showed that as gas started to move through the COx, the sample underwent mechanical dilation (i.e. an increase in sample volume). Under in situ conditions, the onset of dilation (micro-fissuring) is a necessary precursor for the advective movement of gas.
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- 2014
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22. Assessing the Permeability in Anisotropic and Weakly Permeable Porous Rocks Using Radial Pulse Tests
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Christophe Auvray, Albert Giraud, Richard Giot, GeoRessources, and Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
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[PHYS]Physics [physics] ,Pressure drop ,Chemistry ,General Chemical Engineering ,Poromechanics ,Isotropy ,Constitutive equation ,Energy Engineering and Power Technology ,Mechanics ,lcsh:Chemical technology ,lcsh:HD9502-9502.5 ,lcsh:Energy industries. Energy policy. Fuel trade ,Permeability (earth sciences) ,Transverse plane ,Fuel Technology ,Perpendicular ,lcsh:TP1-1185 ,Geotechnical engineering ,Anisotropy - Abstract
International audience; The pulse test is usually considered to be an efficient method for measuring the permeability of weakly permeable porous rocks. Classically, the test consists of imposing a pressure drop on the base of a cylindrical sample and measuring the pressure variations in the upstream and downstream reservoirs. In the present work, we propose a new apparatus and procedure for hollow cylindrical samples in which the pressure drop is imposed in an axial hole and the pressure is measured both in the hole and on the circumference of the sample. Unlike the classical axial pulse test, this configuration results in a flow in both the axial and transversal directions rather than only in the axial direction. For transverse isotropic rocks, this configuration allows the assessment of the permeability in the isotropy planes and normal to the isotropy planes in a single sample when the samples are appropriately oriented. The test is fully hydro-mechanically coupled; therefore, no analytical solution exists. The test is then interpreted through fully coupled numerical modeling in 3D, considering the anisotropy of the samples. In previous works, we developed and implemented a transverse isotropic poroelastic constitutive law in the finite element code Code_Aster (Edf), as well as an inverse method coupled to the numerical modeling for parameter identification. The method is adapted to the radial pulse test and then applied to hollow cylindrical samples of Meuse/Haute-Marne argillite with the axis either parallel or perpendicular to the isotropy planes. Although this method requires 2 samples for the assessment of permeability in the isotropy planes and normal to the isotropy planes in the axial pulse test, the method applied to the radial pulse test allows the assessment of intrinsic permeability in both directions on a single sample, which allows freeing ourselves from a heterogeneity effect.
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- 2013
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23. 2D coupled HM-XFEM modeling with cohesive zone model and applications to fluid-driven fracture network
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Maxime Faivre, Daniele Colombo, Richard Giot, Fabrice Golfier, Patrick Massin, Bertrand Paul, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), IFP Energies nouvelles (IFPEN), Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), ANR-10-LABX-0021,RESSOURCES21,Strategic metal resources of the 21st century(2010), Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D)
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cohesive ,Materials science ,Mechanical Engineering ,Constitutive equation ,Poromechanics ,0211 other engineering and technologies ,02 engineering and technology ,Mechanics ,[SPI.MECA.MSMECA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Materials and structures in mechanics [physics.class-ph] ,X-FEM ,01 natural sciences ,Finite element method ,Physics::Geophysics ,010101 applied mathematics ,Cohesive zone model ,Mechanics of Materials ,Fluid dynamics ,Fracture (geology) ,General Materials Science ,Geotechnical engineering ,0101 mathematics ,Porous medium ,hydraulic fracture ,021101 geological & geomatics engineering ,Extended finite element method - Abstract
International audience; The present work focuses on a new numerical model for the fully coupled hydro-mechanical analysis of groundwater flows through poroelastic saturated media. In particular, the presence and eventual propagation of fluid-driven fractures is accounted for within a non-regularized cohesive zone model. In this paper, the fracture propagation is considered as a reactivation process: the fracture already exists and evolves (i.e. opens or closes) on a pre-defined path initially constrained. The Talon-Curnier constitutive law is considered for the fracture interfaces and its expression has been adapted to the hydro-mechanical coupling related to the fracture evolution. The fluid pressure inside the fracture is governed by the lubrication equation. The momentum-stress balance equations involving fluid flow and deformation of the solid porous matrix are derived within the framework of the generalized Biot theory. The extended finite element method (XFEM) is preferred to a standard finite element spatial discretization in order to easily handle the presence and evolution of dis-continuities in the porous medium. A set of four Lagrange multipliers is introduced to prevent spurious oscillations of the numerical solution at the interface. Comparisons between numerical results and theoretical solution assess the validity of the model presented in this paper. In addition, the hydro-mechanical interactions between neighboring fractures and the effects of the permeability of the porous medium are investigated. We also demonstrate the capability of our model to handle non-planar fracture paths.
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- 2016
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24. Stress Estimation in Reservoirs by a Stochastic Inverse Approach
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Antoine Mazuyer, Richard Giot, Paul Cupillard, Marianne Conin, pierre thore, Cupillard, Paul, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), and Total E&P
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[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,[SDU.STU.GP] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] - Abstract
International audience; The aim of this study is to estimate the initial stress in reservoirs before production using 3D calibrated geomechanical models. We propose an inverse method for estimating stress. Wellbore data can be integrated in a Mechanical Earth Model in order to estimate stresses nearby wells. It yields a first rough estimation in the whole reservoir by a simple interpolation which is not in equilibrium with the external forces and boundary conditions. From this rough stress field, the inversion aims at finding a physically acceptable stress state (i.e.: in equilibrium with the external forces and boundary conditions) that fit the local stresses wells. The forward problem is ensured by a Finite Element Analysis which is able to take into account structures such as faults, which have a significant influence on the stress magnitude and orientation. Inverse loop stops when the stress computed near wells matches the one estimated using borehole data. The uncertainties on the boundary conditions, elastic parameters and the first stress estimation are taken into account with a stochastic approach. In this study, faults are built with a volumetric representation of the core and damage zone by introducing elastic parameters variations within. This representation is possible because only small deformations are expected.
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- 2016
25. Response of Callovo-Oxfordian claystone during drying tests: unsaturated hydromechanical behavior
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Richard Giot, Gilles Armand, Albert Giraud, and Théophile Guillon
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Engineering ,business.industry ,Poromechanics ,Plasticity ,Geotechnical Engineering and Engineering Geology ,Stability (probability) ,Finite element method ,Nonlinear system ,Solid mechanics ,Earth and Planetary Sciences (miscellaneous) ,Geotechnical engineering ,Sensitivity (control systems) ,business ,Anisotropy - Abstract
The French National Agency for Nuclear Waste Management is currently studying the Callovo-Oxfordian claystone as a potential repository for nuclear waste. This study focuses on the hydromechanical (HM) unsaturated response of the rock subjected to hydraulic loading. Static atmosphere drying tests highlighted the HM coupling and mechanical anisotropy of the samples. A coupled poroelastic model was proposed, involving highly nonlinear equations. Numerical simulations were performed using the finite element code Code_Aster. Through a sensitivity analysis, the most suitable parameters for estimation were found to be the Biot coefficient and 3 of the 4 independent parameters of the Van Genuchten–Mualem relations. The parameters were estimated according to an inverse procedure that minimizes a cost functional. The estimates could not outline any hysteretic behavior, but they appeared to be divided into two groups (depending on their fitted values). The convergence and stability of the inverse algorithm were studied, and the results showed that direct computations must be run prior to the inversion to ensure its convergence. No plasticity occurred in the samples (according to the model), whereas irreversible phenomena do take place in situ.
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- 2012
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26. Three-dimensional poromechanical back analysis of the pulse test accounting for transverse isotropy
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Théophile Guillon, A. Giraud, Richard Giot, and Christophe Auvray
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Transverse plane ,Classical mechanics ,Transverse isotropy ,Solid mechanics ,Poromechanics ,Isotropy ,Constitutive equation ,Earth and Planetary Sciences (miscellaneous) ,Rotational symmetry ,Mechanics ,Geotechnical Engineering and Engineering Geology ,Anisotropy ,Mathematics - Abstract
The pulse test is usually considered as an efficient test for measuring the permeability of weakly permeable porous media. It is generally interpreted by comparison of experimental and theoretical curves obtained by a simplified 1D analytical solution. In a previous work, we proposed an improvement for test interpretation, through fully coupled numerical modeling in 2D axisymmetric configurations. The numerical modeling took into account the poromechanical coupling and exhibited 2D effects that cannot be assessed with classical interpretation. The modeling was coupled with an inverse method permitting the assessment of intrinsic permeability, mechanical parameters such as Young’s modulus, and poromechanical coupling parameters such as Biot coefficient. The interpretation of the tests on argillites showed anisotropy of the material and revealed the fundamental importance of this anisotropy for further works. The present paper aims at taking into account the transverse isotropy of the rock samples in the poromechanical back analysis of the test. A transverse isotropic poroelastic constitutive law has been developed and implemented in Code_Aster (Edf), and 3D modeling is required to account for all possible orientations of the samples. The poromechanical modeling is still coupled with an inverse method, also implemented in the finite element code. The method was applied to laboratory tests on Meuse/Haute-Marne argillites, on cylindrical samples with axis either parallel or perpendicular to the isotropy planes, and the results were compared with isotropic interpretation. The 3D transverse isotropic modeling provides more consistent values of the parameters than the 2D modeling, particularly for the mechanical parameters.
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- 2012
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27. Hydromechanical behavior of Tournemire argillites: Measurement of the poroelastic parameters and estimation of the intrinsic permeability by œdometric tests
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E. Bemer, A. Giraud, A. Noiret, Richard Giot, and F. Homand
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Biot number ,Petrophysics ,Constitutive equation ,Isotropy ,Poromechanics ,Computational Mechanics ,Geotechnical Engineering and Engineering Geology ,Oedometer test ,Mechanics of Materials ,Transverse isotropy ,General Materials Science ,Geotechnical engineering ,Oil shale ,Geology - Abstract
Knowledge of shale poromechanical behavior is proven to be essential for various environmental issues such as deep geological storage of CO2, high level radioactive waste storage, oil field abandonment and so forth… This paper sets out the key points of shale experimental characterization within the framework of Biot's mechanics of fluid saturated porous solids. Shales are well known to present a more or less transverse isotropy. This paper describes a full methodology for œdometric tests on such sensitive and weakly permeable material. To illustrate this methodology, measurements carried out on Tournemire argillite are proposed. A transverse isotropic poroelastic model is also used to give a more in depth understanding of the hydromechanical coupling. Copyright © 2010 John Wiley & Sons, Ltd.
- Published
- 2011
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28. Fully coupled poromechanical back analysis of the pulse test by inverse method
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F. Homand, Théophile Guillon, A. Giraud, Richard Giot, and Christophe Auvray
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Mathematical analysis ,Computational Mechanics ,Geotechnical Engineering and Engineering Geology ,Finite element method ,Pulse (physics) ,Parameter identification problem ,Permeability (earth sciences) ,Mechanics of Materials ,Compressibility ,General Materials Science ,Focus (optics) ,Porous medium ,Constant (mathematics) ,Algorithm ,Mathematics - Abstract
In this paper, we investigate the pulse test, which is usually considered as efficient for measuring the permeability of weakly permeable porous media. The pulse is first analyzed and we show that it is a fully poromechanical coupled problem. Owing to those couplings, the problem is 2D-axisymmetrical, rather than 1D as is usually considered to be the case. As a consequence, the 1D solutions, for example under constant mean stress hypothesis, although giving good approximates of permeability and storage coefficient, are not rigorous and an enhanced back analysis of the test requires 2D solutions. Therefore, no analytical solution exists, and the problem has to be solved using 2D-axisymmetrical numerical modelings of the pulse test. The finite element method is considered in this paper. We then proceed to formulate the pulse test back analysis as a parameter identification problem, and we focus on intrinsic permeability, Biot coefficient, drained Young's modulus and reservoir compressibility levels. This parameter identification problem is solved by an inverse method consisting of the minimization of a cost-functional, through a gradient-based algorithm. This new method of interpretation of the pulse test is finally applied to laboratory tests on Meuse/Haute–Marne argillite and is shown to give encouraging results. Copyright © 2010 John Wiley & Sons, Ltd.
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- 2011
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29. Poromechanical Modelling and Inverse Approach of Drying Tests on Weakly Permeable Porous Rocks
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F. Homand, A. Giraud, and Richard Giot
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Permeability (earth sciences) ,Hydrogeology ,Materials science ,Mathematical model ,General Chemical Engineering ,Mass transfer ,Geotechnical engineering ,Boundary value problem ,Mechanics ,Inverse problem ,Porous medium ,Catalysis ,Finite element method - Abstract
The present paper deals with the determination of permeability in partially saturated conditions for weakly permeable porous rocks such as argillites or deep clayey formations. The level of permeability can be obtained via the measurements of transient weight loss of a sample submitted to a decrease in relative humidity imposed by saline solution in a hermetic chamber. An identification method based on simplified uncoupled 1D-linear and 1D-non-linear modelling was presented in a previous paper (Giraud et al. Trans Porous Media 69(2):259–280, 2006). The present paper takes into account generalized mass transfer phenomena such as Darcean advective transport of liquid and gas mixtures and Fickean diffusive transport of the vapour specie inside a gas mixture. Poromechanical coupling as well as 3D effects due to the geometry and finite dimensions of the tested samples are also covered by this approach. The coupled THM finite element computer code Code_Aster is then used to model the forward problem. The parameter identification procedure is based upon the solution of an inverse problem. The Levenberg–Marquardt algorithm was used for the problem of minimization. Comparisons between previous simplified 1D modelling and 2D-axisymmetrical coupled modelling show that the former method efficiently provides the correct order of magnitude of the level of permeability or the equivalent storage coefficients. Due to the boundary condition, the real 2D-axisymmetrical geometry of the sample must not be neglected if we are to obtain accurate results.
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- 2008
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30. Permeability identification of a weakly permeable partially saturated porous rock
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Amine Koriche, Richard Giot, Françoise Homand, and Albert Giraud
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Nonlinear system ,Permeability (earth sciences) ,Finite volume method ,Materials science ,Atmospheric pressure ,Discretization ,Capillary action ,General Chemical Engineering ,Mineralogy ,Mechanics ,Inverse problem ,Porous medium ,Catalysis - Abstract
The present paper deals with the determination of permeability in partially saturated conditions for weakly permeable porous continua such as argillites or deep clayey formations. The permeability can be deduced from measurements of transient weight loss of a sample submitted to a laboratory drying test: a decrease of relative humidity is imposed by saline solution in an hermetic chamber. Assumptions of constant gas pressure equal to atmospheric pressure and of negligible Fickean diffusive transport of vapour are adopted. The only transport phenomenon taken into account inside the sample is the Darcean advective transport of the water liquid. The forward problem is solved by following two modelling approaches: a linear one and a nonlinear one. The parameter identification procedure is based upon the solution of corresponding inverse problems. In the two cases, the Levenberg–Marquardt algorithm has been used for the minimization problem. In the linear approach, the solution of the forward problem is explicit. In the non linear approach, finite volume method for the spatial discretization combined with a Newton–Raphson algorithm has been used to solve the non linear forward problem. The identification method enables variations of permeability and capillary capacity to be estimated. Comparisons between linear and non linear approaches show that the first one is useful to give mean values and order of magnitude of permeability and capacity. A more complete information is deduced from the non linear approach as variations of equivalent capacity and permeability during a test are significant in most cases. The analysis of the obtained results shows that the basic modelling assumption of constant gas pressure inside the sample would not be relevant for lower range of relative humidities and liquid permeability than those investigated.
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- 2006
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31. Three-dimensional finite element modelling of stress relaxation tests in anisotropic clayey medium: direct problem and back analysis
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Albert Giraud, Françoise Homand, and Richard Giot
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Hydrogeology ,Cauchy stress tensor ,Constitutive equation ,Mathematical analysis ,Soil Science ,Inverse transform sampling ,Geology ,Inversion (meteorology) ,Geotechnical Engineering and Engineering Geology ,Finite element method ,Architecture ,Stress relaxation ,Geotechnical engineering ,Anisotropy ,Mathematics - Abstract
This paper deals with a new strategy for initial stress identification by stress relaxation methods, coupled with finite element calculation, and applied to the overcoring test. The back-analysis of such a test uses an inversion method which consists in the minimisation, with a gradient-based algorithm, of a cost functional of least-squares type, which quantizes the difference between measured and computed strains. The computed strains are assessed by three-dimensional finite element modellings of the overcoring test. The inversion methodology is applied to a recent in situ overcoring test performed at Mont Terri laboratory, Switzerland. The inversion gave good results and allows us to validate the inversion methodology. The constitutive law considered for this application is transverse isotropic elasticity but the inversion method developed is applicable to most constitutive laws and every kind of in situ test.
- Published
- 2006
- Full Text
- View/download PDF
32. Effect of suction on the mechanical behaviour of iron ore rock
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Dragan Grgic, Françoise Homand, Albert Giraud, and Richard Giot
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Materials science ,Capillary action ,Effective stress ,Constitutive equation ,Computational Mechanics ,engineering.material ,Geotechnical Engineering and Engineering Geology ,Yield function ,Iron ore ,Mechanics of Materials ,engineering ,Cohesion (geology) ,General Materials Science ,Geotechnical engineering ,Porosity ,Water content - Abstract
The effect of suction on the behaviour of iron ore has been studied from both physical and mechanical points of view. The porosity and the suction phenomena have been analysed using different experimental techniques. Uniaxial compressive tests on partially saturated samples have shown that the suction is responsible for strength and cohesion improvement. Considering the theory of partially saturated porous soils of Coussy and Dangla (Mecanique des sols non satures (2002 edn). Hermes Science: 2002; 390), we have proposed a constitutive law for partially saturated iron ore. The real increase in the apparent cohesion due to the capillary attraction forces is overestimated if the yield function is written in terms of effective stresses. The effect of the capillary cohesion has been modelled with a function in the expression of the apparent cohesion of the yield function. The effect of suction on the mechanical behaviour has been represented in the effective stresses space and in the total stresses space like the Alonso model (Geotechnique 1990; 40:405–430). Copyright © 2005 John Wiley & Sons, Ltd.
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- 2005
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33. THM Modeling of the CO2 Injection in Coal: Influence of Biot's Coefficient and Langmuir'S Adsorption Parameters
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Kanssoune Saliya, Dragan Grgic, Albert Giraud, and Richard Giot
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Langmuir ,Biot number ,business.industry ,Chemistry ,technology, industry, and agriculture ,Rotational symmetry ,Thermodynamics ,Eulerian path ,symbols.namesake ,Adsorption ,symbols ,medicine ,Coal ,Geotechnical engineering ,Swelling ,medicine.symptom ,business ,Porosity - Abstract
CO2 injection in coal can modify the petro-physical properties. Indeed, the coal matrix swelling reduces the porosity and the permeability of coal on the one hand. On the other hand, the increase in gas pressure induces the decrease in the effective stresses and therefore the increase in the spacing between the matrix blocks. We used a theoretical model for the variation of the Eulerian porosity which takes into account the adsorption process. This process is classically modeled with the Langmuir’s isotherm. After implementation in Code_Aster (EDF), we investigated through numerical simulations (1D and 2D axisymmetric) the influence of the Biot’s coefficient and the Langmuir’s adsorption parameters during CO2 injection in coal. This simulations showed that the increase in Langmuir’s parameters, as well as the increase in the Biot’s coefficient, promotes the reduction of the porosity when the gas pressure increases.
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- 2013
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34. Fracturing around radioactive minerals: elastic model and applications
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Richard Giot, Jean-Marc Montel, GeoRessources, and Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
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Shearing (physics) ,Bulk modulus ,010504 meteorology & atmospheric sciences ,Chemistry ,Mineralogy ,Stiffness ,Thorium ,chemistry.chemical_element ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,010502 geochemistry & geophysics ,01 natural sciences ,Mineral resource classification ,Radial fractures ,Metamictization ,Geochemistry and Petrology ,medicine ,General Materials Science ,Swelling ,medicine.symptom ,0105 earth and related environmental sciences - Abstract
International audience; A simplified mechanical model of a metamict crystal swelling in a host mineral shows that enough stress is generated in the host to trigger its failure and the appearance of radial fractures, in agreement with geological observations. The maximum stress, which combines radial compression and concentric tension, occurs along the host-inclusion interface and should create radial fractures. The maximum stress mainly depends on the amount of swelling, on the inclusion stiffness, and on the resistance to shearing of the host mineral. The external pressure, the host bulk modulus, and the inclusions/host radius ratio are parameters of minor relevance. The influence of the inclusion does not extend beyond about five times its radius. The application of published experimental data shows that a swelling metamict mineral may create significant fracturing in the host mineral. However, many parameters for both host and inclusion minerals are not available, even for the application of such a simple model. We think that in some circumstances, swelling of metamict mineral and fracturing of host mineral may significantly affect the physical properties of rocks at a larger scale by creating a network of fractures connecting metamict (i.e. uranium and thorium bearing) minerals to the geological environment.
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- 2013
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35. Interpretation of in situ rock stress measurements by inverse method
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K. Su, A. Giraud, Richard Giot, and F. Homand
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In situ ,Stress (mechanics) ,Mineralogy ,Inverse method ,Geology ,Interpretation (model theory) - Published
- 2006
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36. Poromechanical Modelling and Inverse Approach of Drying Tests on Weakly Permeable Porous Rocks.
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Richard Giot and Françoise Homand
- Subjects
POROSITY ,ADSORPTION (Chemistry) ,SEPARATION (Technology) ,SURFACE chemistry - Abstract
Abstract The present paper deals with the determination of permeability in partially saturated conditions for weakly permeable porous rocks such as argillites or deep clayey formations. The level of permeability can be obtained via the measurements of transient weight loss of a sample submitted to a decrease in relative humidity imposed by saline solution in a hermetic chamber. An identification method based on simplified uncoupled 1D-linear and 1D-non-linear modelling was presented in a previous paper (Giraud et al. Trans Porous Media 69(2):259–280, 2006). The present paper takes into account generalized mass transfer phenomena such as Darcean advective transport of liquid and gas mixtures and Fickean diffusive transport of the vapour specie inside a gas mixture. Poromechanical coupling as well as 3D effects due to the geometry and finite dimensions of the tested samples are also covered by this approach. The coupled THM finite element computer code Code_Aster is then used to model the forward problem. The parameter identification procedure is based upon the solution of an inverse problem. The Levenberg–Marquardt algorithm was used for the problem of minimization. Comparisons between previous simplified 1D modelling and 2D-axisymmetrical coupled modelling show that the former method efficiently provides the correct order of magnitude of the level of permeability or the equivalent storage coefficients. Due to the boundary condition, the real 2D-axisymmetrical geometry of the sample must not be neglected if we are to obtain accurate results. [ABSTRACT FROM AUTHOR]
- Published
- 2009
37. Three-dimensional finite element modelling of stress relaxation tests in anisotropic clayey medium: direct problem and back analysis.
- Author
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Richard Giot, Albert Giraud, and Francoise Homand
- Abstract
Abstract This paper deals with a new strategy for initial stress identification by stress relaxation methods, coupled with finite element calculation, and applied to the overcoring test. The back-analysis of such a test uses an inversion method which consists in the minimisation, with a gradient-based algorithm, of a cost functional of least-squares type, which quantizes the difference between measured and computed strains. The computed strains are assessed by three-dimensional finite element modellings of the overcoring test. The inversion methodology is applied to a recent in situ overcoring test performed at Mont Terri laboratory, Switzerland. The inversion gave good results and allows us to validate the inversion methodology. The constitutive law considered for this application is transverse isotropic elasticity but the inversion method developed is applicable to most constitutive laws and every kind of in situ test. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
38. Initiation and propagation of fractures in anisotropic media, taking into account Hydro-Mechanical couplings
- Author
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Moosavi, Sourena, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, Richard Giot, and Luc Scholtès
- Subjects
Méthodes numériques ,Numerical Methods ,Rock Mechanics ,[PHYS.MECA]Physics [physics]/Mechanics [physics] ,Mécanique des roches ,[SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology ,[INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation ,Numerical Geology ,Géologie numérique - Abstract
Current emphasis in petroleom industry toward increasing the reservoirs efficiency, along with the interest in exploitation of other sources of energy buried deep underground created a renewed interest in rock fracture mechanics in general and hydraulic fracturing specifically. Hydraulic fracturing, informally referred to as “fracking,” is an oil and gas well development process that typically involves injecting water, under high pressure into a bedrock formation via the well. This process is intended to create new fractures in the rock as well as increase the size, extent, and connectivity of existing fractures. However some of the very important features of this process have been overlooked. Among these neglected features one can name of inability of the vast majority of existing models to tackle at once the propagation of hydraulic fractures in fractured rocks-masses where a competing dipole mechanism exists between fracturing of the intact rock and re-activation of exiting fracture networks. Another feature that has been ignored is its intrinsically three dimensionality which is neglected by most models. Among all different types of numerical methods that have been developed in order to assess the mechanism of fracturing phenomenon very few, if any, can handle the entire complexity of such process. In the present thesis, fluid-driven crack initiation and propagation in transverse isotropic rocks is simulated using a coupled model comprising of eXtended Finite Element Method (XFEM) and cohesive zone models. The HM XFEM developed in this thesis is an extension to previous models developed introduced in multiscale hydrogeomechanics team of GeoRessources. An emphasis is put on considering the anisotropic nature of the medium and on studying its influence on the propagation path. This latter is investigated by the concept of bifurcation angle previously introduced in literature. In complementary efforts was made to have a better understanding of crack initiation in transversely isotropic media, we also used the discrete element method (DEM) in order to gain insights into the mechanisms at stake. Both methods exhibit their advantages and disadvantages in modeling fracturing phenomenon. The different nature of two methods, DEM being a discontinuous and XFEM being a continuous method, reveals potentials of both methods and renders a good comparison of which method suits the problem in hand the best, considering the the objectives of the design; L’accent mis actuellement par l’industrie pétrolière sur l’augmentation de l’efficacité des réservoirs, ainsi que sur l’intérêt grandissant pour l’exploitation d’autres sources d’énergie enfouies profondément sous terre a suscité un regain d’intérêt pour la mécanique de la fracturation des roches en général et la fracturation hydraulique en particulier. La fracturation hydraulique, appelée de manière informelle “fracturation”, est un processus qui consiste généralement à injecter de l’eau, sous haute pression dans une formation rocheuse via le puits. Ce processus vise à créer de nouvelles fractures dans la roche et à augmenter la taille, l’étendue et la connectivité des fractures existantes. Des avancées récentes dans la modélisation et la simulation de fractures hydrauliques ont eu lieu, au confluent de facteurs qui incluent une activité accrue, une tendance vers une complexité accrue et une compréhension approfondie du modèle mathématique sous-jacent et de ses défis intrinsèques. Cependant, certaines des caractéristiques très importantes de ce processus ont été négligées. Parmi les caractéristiques négligées, on peut citer l’incapacité de la grande majorité des modèles existants de s’attaquer à la fois à la propagation de fractures hydrauliques dans la roche intacte, à l’inititation de nouvelles fractures ainsi qu’à la réactivation des fractures existantes. Une autre caractéristique qui a été ignorée est sa dimension intrinsèque en trois dimensions, négligée par la plupart des modèles actuallement proposés. Parmi tous les différents types de méthodes numériques développées pour évaluer le mécanisme du phénomène de fracturation, très peu sont capables de représenter la totalité des mecanismes mis en jeu. Dans la présente thèse, l’initiation et la propagation de fissures induites par les fluides dans des roches isotropes transversales sont simulées à l’aide d’un modèle hydromécanique (HM) couplé basé la méthode XFEM (eXtended Finite Element Method) et un modèle de zones cohésives. Le HM-XFEM développé dans cette thèse est une extension des modèles précédemment développés dans l’équipe hydro-géomécanique multi échelle de GeoRessources. L’accent a été porté plus particulièrement sur la prise en compte de l’anisotropie du milieu et sur son influence sur le chemin de propagation. Ce dernier est défini à partir du le concept d’angle de bifurcation introduit auparavant dans la littérature. En complément des développements réalisés dans le modèle HM-XFEM, effort a été fait pour mieux comprendre l’initiation de la fissure en utilisant la méthode des éléments discrets (DEM) à l’aide du logiciel open source YADE Open DEM. La nature différente des deux méthodes, DEM étant une méthode discontinue et XFEM, une méthode continue, révèle les potentiels des deux méthodes et permet de comparer correctement la méthode qui convient le mieux au problème à résoudre, compte tenu des objectifs de la conception
- Published
- 2018
39. Initiation et propagation de la fracturation en milieu anisotrope avec prise en compte des couplages hydro-mécaniques
- Author
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Moosavi, Sourena, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, Richard Giot, and Luc Scholtès
- Subjects
Méthodes numériques ,Numerical Methods ,Rock Mechanics ,[PHYS.MECA]Physics [physics]/Mechanics [physics] ,Mécanique des roches ,[SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology ,[INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation ,Numerical Geology ,Géologie numérique - Abstract
Current emphasis in petroleom industry toward increasing the reservoirs efficiency, along with the interest in exploitation of other sources of energy buried deep underground created a renewed interest in rock fracture mechanics in general and hydraulic fracturing specifically. Hydraulic fracturing, informally referred to as “fracking,” is an oil and gas well development process that typically involves injecting water, under high pressure into a bedrock formation via the well. This process is intended to create new fractures in the rock as well as increase the size, extent, and connectivity of existing fractures. However some of the very important features of this process have been overlooked. Among these neglected features one can name of inability of the vast majority of existing models to tackle at once the propagation of hydraulic fractures in fractured rocks-masses where a competing dipole mechanism exists between fracturing of the intact rock and re-activation of exiting fracture networks. Another feature that has been ignored is its intrinsically three dimensionality which is neglected by most models. Among all different types of numerical methods that have been developed in order to assess the mechanism of fracturing phenomenon very few, if any, can handle the entire complexity of such process. In the present thesis, fluid-driven crack initiation and propagation in transverse isotropic rocks is simulated using a coupled model comprising of eXtended Finite Element Method (XFEM) and cohesive zone models. The HM XFEM developed in this thesis is an extension to previous models developed introduced in multiscale hydrogeomechanics team of GeoRessources. An emphasis is put on considering the anisotropic nature of the medium and on studying its influence on the propagation path. This latter is investigated by the concept of bifurcation angle previously introduced in literature. In complementary efforts was made to have a better understanding of crack initiation in transversely isotropic media, we also used the discrete element method (DEM) in order to gain insights into the mechanisms at stake. Both methods exhibit their advantages and disadvantages in modeling fracturing phenomenon. The different nature of two methods, DEM being a discontinuous and XFEM being a continuous method, reveals potentials of both methods and renders a good comparison of which method suits the problem in hand the best, considering the the objectives of the design; L’accent mis actuellement par l’industrie pétrolière sur l’augmentation de l’efficacité des réservoirs, ainsi que sur l’intérêt grandissant pour l’exploitation d’autres sources d’énergie enfouies profondément sous terre a suscité un regain d’intérêt pour la mécanique de la fracturation des roches en général et la fracturation hydraulique en particulier. La fracturation hydraulique, appelée de manière informelle “fracturation”, est un processus qui consiste généralement à injecter de l’eau, sous haute pression dans une formation rocheuse via le puits. Ce processus vise à créer de nouvelles fractures dans la roche et à augmenter la taille, l’étendue et la connectivité des fractures existantes. Des avancées récentes dans la modélisation et la simulation de fractures hydrauliques ont eu lieu, au confluent de facteurs qui incluent une activité accrue, une tendance vers une complexité accrue et une compréhension approfondie du modèle mathématique sous-jacent et de ses défis intrinsèques. Cependant, certaines des caractéristiques très importantes de ce processus ont été négligées. Parmi les caractéristiques négligées, on peut citer l’incapacité de la grande majorité des modèles existants de s’attaquer à la fois à la propagation de fractures hydrauliques dans la roche intacte, à l’inititation de nouvelles fractures ainsi qu’à la réactivation des fractures existantes. Une autre caractéristique qui a été ignorée est sa dimension intrinsèque en trois dimensions, négligée par la plupart des modèles actuallement proposés. Parmi tous les différents types de méthodes numériques développées pour évaluer le mécanisme du phénomène de fracturation, très peu sont capables de représenter la totalité des mecanismes mis en jeu. Dans la présente thèse, l’initiation et la propagation de fissures induites par les fluides dans des roches isotropes transversales sont simulées à l’aide d’un modèle hydromécanique (HM) couplé basé la méthode XFEM (eXtended Finite Element Method) et un modèle de zones cohésives. Le HM-XFEM développé dans cette thèse est une extension des modèles précédemment développés dans l’équipe hydro-géomécanique multi échelle de GeoRessources. L’accent a été porté plus particulièrement sur la prise en compte de l’anisotropie du milieu et sur son influence sur le chemin de propagation. Ce dernier est défini à partir du le concept d’angle de bifurcation introduit auparavant dans la littérature. En complément des développements réalisés dans le modèle HM-XFEM, effort a été fait pour mieux comprendre l’initiation de la fissure en utilisant la méthode des éléments discrets (DEM) à l’aide du logiciel open source YADE Open DEM. La nature différente des deux méthodes, DEM étant une méthode discontinue et XFEM, une méthode continue, révèle les potentiels des deux méthodes et permet de comparer correctement la méthode qui convient le mieux au problème à résoudre, compte tenu des objectifs de la conception
- Published
- 2018
40. Consideration of anisotropy in the instantaneous behaviour of geomaterials for underground structure calculations
- Author
-
Djouadi, Inès, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), EDF (EDF), Université de Lorraine, Richard Giot, and Albert Giraud
- Subjects
Plasticity ,Anisotropie ,Geomaterials ,Constitutive model ,Excavation ,Géomatériaux ,Comportement instantané ,[PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph] ,Finite-element ,[SPI.GCIV]Engineering Sciences [physics]/Civil Engineering ,Plasticité ,Ouvrages souterrains ,Stockage profond ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Anisotropy ,Deep geological storage ,Éléments-finis ,Instant behaviour ,Modèle de comportement ,Underground facility - Abstract
Within the framework of radioactive waste management, for long-lived and high-level radioactive waste, France has chosen deep geological storage. This storage will be located in a rock formation, in the east of the basin Parisian, in a tectonically stable area. This Callovo-Oxfordian claystone formation was chosen for its radionuclides retention properties since it is not very permeable. An underground research laboratory was built 500 meters deep to study the properties of the rock in-situ. The Callovo-Oxfordian claystone has been shown to exhibit anisotropy related to its geological formation. The main objective of this PhD thesis is to reproduce anisotropic mechanical behaviour using an elasto-plastic constitutive model. The thermo-elasto-viscoplastic and isotropic behaviour model named LKR is the result of all EDF’s knowledge and expertise in the design of underground structures. Therefore, we seek to apply a method of taking into account structural or inherent anisotropy characterizing several types of geomaterials including Callovo-Oxfordian claystone to this LKR constitutive model. In order to achieve this objective, two methods of taking anisotropy into account and developed in the scientific literature are applied to a Drucker-Prager model with linear softening and then are compared to each other. The first method consists of introducing a microstructure or fabric tensor to define the preferential orientations of the material. The second method is the weakness plane approach which consists of describing the anisotropic behaviour of the material through two distinct mechanisms, one describing the behaviour of the isotropic rock matrix and the other describing the weakness planes. It is through this second mechanism that anisotropy is introduced. These two applications were made using the free mechanical simulation software, Code Aster, developed by EDF. This allowed to understand the numerical difficulties of each of these methods, and to choose the most relevant approach for the extension of the LKR model. Thus, it is the method with the fabric tensor which is, in our case, the most suitable. It was therefore applied to the LKR model. This new extension to the model enables the material orientation dependency of the compression strengths to be taken into account. In this work, the mechanics of continuous media are considered. Anisotropy is introduced only into the elasto-plastic mechanism of the LKR behaviour model.; Dans le cadre de la gestion des déchets radioactifs dits de moyenne activité à vie longue et de haute activité, la France a fait le choix du stockage géologique profond dans une formation rocheuse située à l’est du bassin parisien, dans une zone tectoniquement stable. Cette formation d’argilites du Callovo-Oxfordien a été choisie pour ses propriétés de rétention des radionucléides puisqu’elle est très peu perméable. Un laboratoire de recherche souterrain a été construit à environ 500 mètres de profondeur afin d’étudier in-situ les propriétés de la roche. Il a été montré que l’argilite du Callovo-Oxfordien présente une anisotropie liée à sa formation géologique. L’objectif principal de cette thèse est de pouvoir reproduire le comportement mécanique anisotrope à l’aide d’un modèle de comportement élasto-plastique. Le modèle de comportement thermo-élasto-viscoplastique et isotrope nommé LKR est la résultante de tout le savoir-faire et l’expertise d’EDF en ce qui concerne le dimensionnement d’ouvrages souterrains. On cherche donc à appliquer une méthode de prise en compte de l’anisotropie structurelle caractérisant plusieurs types de géomatériaux dont l’argilite du Callovo-Oxfordien à ce modèle de comportement. Afin d’atteindre cet objectif, deux méthodes de prise en compte de l’anisotropie développées dans la littérature scientifique sont appliquées à un modèle de Drucker-Prager à écrouissage linéaire négatif et sont comparées. La première méthode consiste à introduire un tenseur de microstructure ou de fabrique permettant de définir les orientations préférentielles du matériau. La seconde méthode est l’approche par plan de faiblesse qui consiste à décrire le comportement anisotrope du matériau via deux mécanismes distincts, l’un décrivant le comportement de la matrice rocheuse isotrope et l’autre décrivant les plans de faiblesse. C’est par ce deuxième mécanisme que l’anisotropie est introduite. Ces deux applications ont été faites dans le logiciel libre de simulation en mécanique, Code Aster, développé par EDF et ont permis d’appréhender les difficultés numériques de chacune de ces méthodes, et de choisir l’approche la plus pertinente pour l’extension du modèle LKR. Ainsi, c’est la méthode avec le tenseur de fabrique qui est, dans notre cas, la plus adaptée. Elle a donc été appliquée au modèle LKR. Cette nouvelle extension au modèle permet de prendre en compte la dépendance à l’orientation du matériau des résistances en compression. Dans ces travaux, on se place dans le cadre de la mécanique des milieux continus. L’anisotropie est introduite seulement dans le mécanisme élasto-plastique du modèle de comportement LKR.
- Published
- 2018
41. Prise en compte de l'anisotropie dans le comportement instantané des géomatériaux pour les calculs d'ouvrages souterrains
- Author
-
Djouadi, Inès, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), EDF (EDF), Université de Lorraine, Richard Giot, and Albert Giraud
- Subjects
Plasticity ,Anisotropie ,Geomaterials ,Constitutive model ,Excavation ,Géomatériaux ,Comportement instantané ,[PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph] ,Finite-element ,[SPI.GCIV]Engineering Sciences [physics]/Civil Engineering ,Plasticité ,Ouvrages souterrains ,Stockage profond ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Anisotropy ,Deep geological storage ,Éléments-finis ,Instant behaviour ,Modèle de comportement ,Underground facility - Abstract
Within the framework of radioactive waste management, for long-lived and high-level radioactive waste, France has chosen deep geological storage. This storage will be located in a rock formation, in the east of the basin Parisian, in a tectonically stable area. This Callovo-Oxfordian claystone formation was chosen for its radionuclides retention properties since it is not very permeable. An underground research laboratory was built 500 meters deep to study the properties of the rock in-situ. The Callovo-Oxfordian claystone has been shown to exhibit anisotropy related to its geological formation. The main objective of this PhD thesis is to reproduce anisotropic mechanical behaviour using an elasto-plastic constitutive model. The thermo-elasto-viscoplastic and isotropic behaviour model named LKR is the result of all EDF’s knowledge and expertise in the design of underground structures. Therefore, we seek to apply a method of taking into account structural or inherent anisotropy characterizing several types of geomaterials including Callovo-Oxfordian claystone to this LKR constitutive model. In order to achieve this objective, two methods of taking anisotropy into account and developed in the scientific literature are applied to a Drucker-Prager model with linear softening and then are compared to each other. The first method consists of introducing a microstructure or fabric tensor to define the preferential orientations of the material. The second method is the weakness plane approach which consists of describing the anisotropic behaviour of the material through two distinct mechanisms, one describing the behaviour of the isotropic rock matrix and the other describing the weakness planes. It is through this second mechanism that anisotropy is introduced. These two applications were made using the free mechanical simulation software, Code Aster, developed by EDF. This allowed to understand the numerical difficulties of each of these methods, and to choose the most relevant approach for the extension of the LKR model. Thus, it is the method with the fabric tensor which is, in our case, the most suitable. It was therefore applied to the LKR model. This new extension to the model enables the material orientation dependency of the compression strengths to be taken into account. In this work, the mechanics of continuous media are considered. Anisotropy is introduced only into the elasto-plastic mechanism of the LKR behaviour model.; Dans le cadre de la gestion des déchets radioactifs dits de moyenne activité à vie longue et de haute activité, la France a fait le choix du stockage géologique profond dans une formation rocheuse située à l’est du bassin parisien, dans une zone tectoniquement stable. Cette formation d’argilites du Callovo-Oxfordien a été choisie pour ses propriétés de rétention des radionucléides puisqu’elle est très peu perméable. Un laboratoire de recherche souterrain a été construit à environ 500 mètres de profondeur afin d’étudier in-situ les propriétés de la roche. Il a été montré que l’argilite du Callovo-Oxfordien présente une anisotropie liée à sa formation géologique. L’objectif principal de cette thèse est de pouvoir reproduire le comportement mécanique anisotrope à l’aide d’un modèle de comportement élasto-plastique. Le modèle de comportement thermo-élasto-viscoplastique et isotrope nommé LKR est la résultante de tout le savoir-faire et l’expertise d’EDF en ce qui concerne le dimensionnement d’ouvrages souterrains. On cherche donc à appliquer une méthode de prise en compte de l’anisotropie structurelle caractérisant plusieurs types de géomatériaux dont l’argilite du Callovo-Oxfordien à ce modèle de comportement. Afin d’atteindre cet objectif, deux méthodes de prise en compte de l’anisotropie développées dans la littérature scientifique sont appliquées à un modèle de Drucker-Prager à écrouissage linéaire négatif et sont comparées. La première méthode consiste à introduire un tenseur de microstructure ou de fabrique permettant de définir les orientations préférentielles du matériau. La seconde méthode est l’approche par plan de faiblesse qui consiste à décrire le comportement anisotrope du matériau via deux mécanismes distincts, l’un décrivant le comportement de la matrice rocheuse isotrope et l’autre décrivant les plans de faiblesse. C’est par ce deuxième mécanisme que l’anisotropie est introduite. Ces deux applications ont été faites dans le logiciel libre de simulation en mécanique, Code Aster, développé par EDF et ont permis d’appréhender les difficultés numériques de chacune de ces méthodes, et de choisir l’approche la plus pertinente pour l’extension du modèle LKR. Ainsi, c’est la méthode avec le tenseur de fabrique qui est, dans notre cas, la plus adaptée. Elle a donc été appliquée au modèle LKR. Cette nouvelle extension au modèle permet de prendre en compte la dépendance à l’orientation du matériau des résistances en compression. Dans ces travaux, on se place dans le cadre de la mécanique des milieux continus. L’anisotropie est introduite seulement dans le mécanisme élasto-plastique du modèle de comportement LKR.
- Published
- 2018
42. Estimation de l'état de contrainte initial in situ dans les réservoirs par approche inverse
- Author
-
Mazuyer, Antoine, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, Richard Giot, Paul Cupillard, and Pierre Thore
- Subjects
Géomécanique ,Integrated libraries ,Modélisation ,Failles ,Inverse approach ,État de contrainte ,Stress state ,Geomechanics ,Fault modeling ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,Bibliothèques intégratives ,[SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology ,Approche inverse - Abstract
Initial stress state is the stress state before any human activity. Its knowledge is essential when dealing with scientific (understanding of plate tectonics), preventive (earthquake prediction) and industrial (understanding reservoirs before their exploitation) purposes. We present a method to estimate the initial stress state in a 3D domain from sparse data. This method relies on an inverse approach which uses the finite elements method to solve the elastic mechanical problem. The model parameters are Neumann conditions, which are defined as piecewise linear functions. The data parameters are stress state observations, such as intensity and orientation at a few points. An ensemble optimization method is used to solve the inverse problem. The method is tested on a synthetic case where the reference solution is known. On this example, the method succeeds in retrieving the stress state at data points as well as in the whole domain. The method is enriched with a mechanical criterion which imposes mechanical constraints in the domain under study. The method is then applied to a real case: the Neuquèn basin in Argentina where borehole stress data is available. This application reveals some of the limits of the presented method. Then, the effect of faults on the stress state is investigated. Different modeling strategies are presented: the objective is to reduce the computing cost, which can be very high when dealing with such complex structures. We propose to model them using only elastic properties. Finally, we present the integrative software which were developed to run mechanical simulations. RINGMesh handles the structural model data structure and RINGMecha runs the mechanical simulations on the model. RINGMecha is interfaced with several simulators. Each of them can be called separately, depending on the problem to be solved. The interface of RINGMecha with third party simulators is done in a user friendly manner. RINGMecha was used for all the computations presented in this thesis. It was built in order to be extended to other problems, with other simulators; L'état de contrainte initial est l'état de contrainte dans le sous-sol avant toute intervention humaine. Sa connaissance est essentielle pour atteindre des objectifs aussi bien scientifiques (compréhension de la tectonique des plaques) que préventifs (étude et prédiction des séismes) ou industriels (compréhension de la mécanique des réservoirs pétroliers pour leur exploitation). Dans cette thèse, nous présentons une méthode permettant d'estimer l'état de contrainte initial en trois dimensions, à partir de données éparses. Cette méthode repose sur une approche inverse dans laquelle la méthode des éléments finis est utilisée pour résoudre le problème mécanique élastique. Les paramètres de modèles sont les conditions de Neumann décrites par des fonctions linéaires par morceaux. Les données sont des mesures partielles de l'état de contrainte en quelques points du domaine d'étude. Une optimisation d'ensemble est utilisée pour résoudre le problème inverse. La méthode est testée sur un cas synthétique où la solution de référence dans tout le domaine est supposée connue. Sur cet exemple, la méthode présentée est capable de retrouver un état de contrainte en accord avec les mesures, et cohérent avec l'état de contrainte de référence dans tout le domaine. La méthode est ensuite enrichie par des critères mécaniques qui contraignent l'état de contrainte dans les zones où les données sont absentes. La méthode est ensuite appliquée sur un cas réel: le bassin de Neuquèn en Argentine, sur lequel des données de puits sont disponibles. La confrontation de la méthode avec un cas d'étude permet de déterminer quelles en sont les limites. L'impact des failles sur l'état de contrainte et les différentes façons de les modéliser sont discutés. En effet, la prise en compte de ces structures complexes est problématique dans les calculs induits par les méthodes inverses puisqu'elles introduisent des non linéarités rendant le temps de calcul trop important. Nous investiguons alors la possibilité de les modéliser uniquement par des propriétés élastiques. Enfin, nous consacrons un chapitre sur l'environnement logiciel intégratif que nous avons développé pour la réalisation des calculs mécaniques. Cet environnement est composé de RINGMesh, une bibliothèque proposant une structure de données pour les modèles géologiques et de RINGMecha, permettant la réalisation de calculs mécaniques sur ces modèles. RINGMecha interface plusieurs simulateurs, chacun ayant ses spécificités, de manière totalement transparente pour l'utilisateur. RINGMecha a été utilisé pour la réalisation de tous les calculs présentés dans cette thèse et a été pensé pour pouvoir être étendu à d'autres problèmes, avec d'autres simulateurs
- Published
- 2018
43. In situ stress state estimation in reservoirs using an inverse approach
- Author
-
Mazuyer, Antoine, STAR, ABES, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, Richard Giot, Paul Cupillard, and Pierre Thore
- Subjects
Integrated libraries ,Inverse approach ,État de contrainte ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,Geomechanics ,Géomécanique ,Modélisation ,[SDU.STU.AG] Sciences of the Universe [physics]/Earth Sciences/Applied geology ,Failles ,Stress state ,[SDU.STU] Sciences of the Universe [physics]/Earth Sciences ,Fault modeling ,Bibliothèques intégratives ,[SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology ,Approche inverse - Abstract
Initial stress state is the stress state before any human activity. Its knowledge is essential when dealing with scientific (understanding of plate tectonics), preventive (earthquake prediction) and industrial (understanding reservoirs before their exploitation) purposes. We present a method to estimate the initial stress state in a 3D domain from sparse data. This method relies on an inverse approach which uses the finite elements method to solve the elastic mechanical problem. The model parameters are Neumann conditions, which are defined as piecewise linear functions. The data parameters are stress state observations, such as intensity and orientation at a few points. An ensemble optimization method is used to solve the inverse problem. The method is tested on a synthetic case where the reference solution is known. On this example, the method succeeds in retrieving the stress state at data points as well as in the whole domain. The method is enriched with a mechanical criterion which imposes mechanical constraints in the domain under study. The method is then applied to a real case: the Neuquèn basin in Argentina where borehole stress data is available. This application reveals some of the limits of the presented method. Then, the effect of faults on the stress state is investigated. Different modeling strategies are presented: the objective is to reduce the computing cost, which can be very high when dealing with such complex structures. We propose to model them using only elastic properties. Finally, we present the integrative software which were developed to run mechanical simulations. RINGMesh handles the structural model data structure and RINGMecha runs the mechanical simulations on the model. RINGMecha is interfaced with several simulators. Each of them can be called separately, depending on the problem to be solved. The interface of RINGMecha with third party simulators is done in a user friendly manner. RINGMecha was used for all the computations presented in this thesis. It was built in order to be extended to other problems, with other simulators, L'état de contrainte initial est l'état de contrainte dans le sous-sol avant toute intervention humaine. Sa connaissance est essentielle pour atteindre des objectifs aussi bien scientifiques (compréhension de la tectonique des plaques) que préventifs (étude et prédiction des séismes) ou industriels (compréhension de la mécanique des réservoirs pétroliers pour leur exploitation). Dans cette thèse, nous présentons une méthode permettant d'estimer l'état de contrainte initial en trois dimensions, à partir de données éparses. Cette méthode repose sur une approche inverse dans laquelle la méthode des éléments finis est utilisée pour résoudre le problème mécanique élastique. Les paramètres de modèles sont les conditions de Neumann décrites par des fonctions linéaires par morceaux. Les données sont des mesures partielles de l'état de contrainte en quelques points du domaine d'étude. Une optimisation d'ensemble est utilisée pour résoudre le problème inverse. La méthode est testée sur un cas synthétique où la solution de référence dans tout le domaine est supposée connue. Sur cet exemple, la méthode présentée est capable de retrouver un état de contrainte en accord avec les mesures, et cohérent avec l'état de contrainte de référence dans tout le domaine. La méthode est ensuite enrichie par des critères mécaniques qui contraignent l'état de contrainte dans les zones où les données sont absentes. La méthode est ensuite appliquée sur un cas réel: le bassin de Neuquèn en Argentine, sur lequel des données de puits sont disponibles. La confrontation de la méthode avec un cas d'étude permet de déterminer quelles en sont les limites. L'impact des failles sur l'état de contrainte et les différentes façons de les modéliser sont discutés. En effet, la prise en compte de ces structures complexes est problématique dans les calculs induits par les méthodes inverses puisqu'elles introduisent des non linéarités rendant le temps de calcul trop important. Nous investiguons alors la possibilité de les modéliser uniquement par des propriétés élastiques. Enfin, nous consacrons un chapitre sur l'environnement logiciel intégratif que nous avons développé pour la réalisation des calculs mécaniques. Cet environnement est composé de RINGMesh, une bibliothèque proposant une structure de données pour les modèles géologiques et de RINGMecha, permettant la réalisation de calculs mécaniques sur ces modèles. RINGMecha interface plusieurs simulateurs, chacun ayant ses spécificités, de manière totalement transparente pour l'utilisateur. RINGMecha a été utilisé pour la réalisation de tous les calculs présentés dans cette thèse et a été pensé pour pouvoir être étendu à d'autres problèmes, avec d'autres simulateurs
- Published
- 2018
44. Modeling fluid-driven cracks with the extended finite element method
- Author
-
Paul, Bertrand, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Université de Lorraine, Richard Giot, and Patrick Massin
- Subjects
Hydraulic fracture ,Fracture ,Éléments quadratiques ,XFEM ,Zone cohésive ,[SPI.GCIV.GEOTECH]Engineering Sciences [physics]/Civil Engineering/Géotechnique ,Hydro-Mechanical Coupling ,Fracture hydraulique ,Couplage hydro-Mécanique ,Quadratic Elements ,Fissuration ,Cohesive Zone Model - Abstract
The permeability of rocks is widely affected by the presence of fractures as it establishes prevailing paths for the fluid flow. Natural cracks are then a critical factor for a reservoir productiveness. For low permeability rocks, stimulation techniques such as hydrofracturing have been experienced to enhance the permeability, so that the reservoir becomes profitable. In the opposite, when it comes to geological storage, the presence of cracks constitutes a major issue since it encourages the leak and migration of the material spread in the rock. In the case of CO2 storage, the scenario of leakage across the reservoir seal through cracks or revived faults is a matter of great concern. And as for nuclear waste storage, the fluid circulation in a fracture network around the storage cavity can obviously lead to the migration of toxic materials. It is then crucial to predict the effects of the presence of cracks in a reservoir. The main purpose of this work is the design of a numerical tool to simulate a crack network and its evolution under hydromechanical loading. To achieve this goal we chose the eXtended Finite Element Method (XFEM) for its convenience, and a cohesive zone model to handle the crack tip area. The XFEM is a meshfree method that allows us to introduce cracks in the model without necessarily remeshing in case of crack propagation. The fluid flow in the crack as well as the exchanges between the porous rock and the crack are accounted for through an hydro-mechanical coupling. The model is validated with an analytical asymptotic solution for the propagation of a plane hydraulic fracture in a poroelastic media, in 2D as well as in 3D. Then we study the propagation of hydraulic fractures on non predefined paths. The cracks are initially introduced as large potential crack surfaces so that the cohesive law will naturally separate adherent and debonding zones. The potential crack surfaces are then updated based on a directional criterion appealing to cohesive integrals only. Several examples of crack reorientation and competition between nearby cracks are presented. Finally, we extend our model to account for the presence of fracture junctions; La perméabilité des roches est fortement influencée par la présence de fractures car ces dernières constituent un chemin préférentiel pour l’écoulement des fluides. Ainsi la présence de fractures naturelles est un facteur déterminant pour la productivité d’un réservoir. Dans le cas de roches à faible conductivité, des techniques de stimulation telle que la fracturation hydraulique sont utilisées pour en augmenter la perméabilité et rendre le réservoir exploitable d’un point de vue économique. A l’inverse, dans le cas du stockage géologique, la présence de fractures dans la roche représente un danger dans la mesure où elle facilite le transport et la migration des espèces disséminées dans la roche. Pour le stockage de CO2, les fuites par les fractures présentes dans les couvertures du réservoir et la réactivation des failles constituent un risque majeur. Et en ce qui concerne le stockage géologique de déchets radioactifs, la circulation de fluide dans des réseaux de fractures nouvelles ou réactivées au voisinage de la zone de stockage peut aboutir à la migration de matériaux nocifs. Il est donc important de prévoir les effets de la présence de fractures dans un réservoir. Le but de cette thèse est le développement d’un outil numérique pour la simulation d’un réseau de fractures et de son évolution sous sollicitation hydro-mécanique. Grâce à sa commodité, la méthode des éléments finis étendue (XFEM) sera retenue et associée à un modèle de zone cohésive. La méthode XFEM permet en effet l’introduction de fissures dans le modèle sans nécessairement remailler en cas de propagation des fissures. L’écoulement du fluide dans la fissure et les échanges de fluide entre la fissure et le milieu poreux seront pris en compte via un couplage hydro-mécanique. Le modèle est validé avec une solution analytique asymptotique pour la propagation d’une fracture hydraulique plane dans un milieu poroélastique en 2D comme en 3D. Puis, nous étudions la propagation de fractures hydrauliques sur trajets inconnus. Les fissures sont initialement introduites comme des surfaces de fissuration potentielles étendues. Le modèle de zone cohésive sépare naturellement les domaines adhérents et ouverts. Les surfaces potentielles de fissuration sont alors actualisées de manière implicite par un post-traitement de l’état cohésif. Divers exemples de réorientation de fissures hydrauliques et de compétition entre fissures voisines sont analysés. Enfin, nous présentons l’extension du modèle aux jonctions de fractures hydrauliques
- Published
- 2016
45. Modeling of the hydro-geomechanical behavior of a fault network under the stress-state variations
- Author
-
Faivre, Maxime, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Université de Lorraine, Fabrice Golfier, Richard Giot, ANR-10-LABX-0021,RESSOURCES21,Strategic metal resources of the 21st century(2010), UL, Thèses, and Laboratoires d'excellence - Labex - Strategic metal resources of the 21st century - - RESSOURCES212010 - ANR-10-LABX-0021 - LABX - VALID
- Subjects
XFEM method ,Fracturation hydraulique ,Rupture ,[SPI.OTHER]Engineering Sciences [physics]/Other ,[SPI.OTHER] Engineering Sciences [physics]/Other ,Matériaux poreux -- Fluides ,non-regularized cohesive constitutive law ,Dynamique des ,Réseau de fractures hydrauliques ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,fluid-driven fracture network ,Contraintes (mécanique) ,Méthode XFEM ,Mécanique de la rupture ,stress-shadowing effect ,fluid circulation ,fracture mechanics ,[SDU.STU] Sciences of the Universe [physics]/Earth Sciences ,Loi cohésive non-régularisée ,Circulation de fluide ,KGD ,Failles (géologie) ,Mécanique de la - Abstract
In the present work, we address the issue of groundwater flow in the fractured porous media submitted to local or regional stress-state variations. Due to the increasing pore fluid pressure, the length and aperture distribution of the fractures are modified resulting in the formation of preferential flow channels within the geological formation. The numerical approach proposed is a fully coupled hydro-poro-mechanical model in saturated conditions involving single-phase flow both in fractures and in the porous matrix. The extended finite element method (XFEM) is employed for modeling fracture dynamics and flow calculation for fracture which do not lie on the mesh but cross through the elements. In this study: (i) we consider the pressure build up generated by fluid flow inside and through the fracture, (ii) the fracture dynamics by using a cohesive zone model (CZM) on pre-existing propagation path and (iii) fluid exchanges may occur in between fractures and porous medium. The last specification of the HM-XFEM model is taken into account through the introduction of a Lagrange multiplier field along the fracture path. These fields are the result of the dualised condition of pressure continuity between the pore pressure and the fluid pressure inside the fracture. As a function of the Lagrange multiplier value, both permeable and impervious fractures can be considered. The cohesive law employed is a non-regularized-type cohesive law to ensure propagation and eventually closure of the fracture. Validation of the model has been conducted by means of the well-known KGD fracture model when different propagation regimes are considered. We applied the HM-XFEM model to the case of multi-stage fracture network stimulated by the injection of incompressible fluid at constant rate. Fractures are not connected to each other and evolve on pre-existing propagation paths. We aim at appreciating the influence of the fluid viscosity, the injection rate and spacing between each fracture, on the fracture propagation. A peculiar attention is paid to the stress-shadowing effect (i.e. interaction between fractures)., Nous présentons dans ce mémoire l'influence que peuvent avoir les écoulements de fluide au sein de la matrice rocheuse fracturée, laquelle est sujette aux variations locales ou régionales de l'état de contrainte in situ. Du fait de l'augmentation de la pression de pore, la longueur et l'ouverture de la (les) fracture(s) peuvent subir des variations significatives et conduire à la formation de chemins préférentiels pour l'écoulement du fluide dans le milieu géologique. Les modèles théorique et numérique évoqués ici sont des modèles de comportement hydro-mécanique pour le milieu poreux saturé en présence d'une seule phase fluide. La méthode des éléments finis étendue (XFEM) est utilisée afin de modéliser la dynamique des fractures ainsi que les écoulements de fluide dans la matrice rocheuse fracturée, sans être tributaire de la dépendance au maillage. Ainsi, nous considérons: (i) qu'il existe une pression fluide induite par l'écoulement au sein de la fracture, (ii) que la dynamique de la fracture est gérée grâce à un modèle de zone cohésive en supposant un chemin de propagation prédéfini, et (iii) que des échanges entre la fracture et la matrice poreuse peuvent se produire. Ce dernier aspect sera pris en compte en introduisant, dans la formulation du problème couplé, un champ de multiplicateur de Lagrange. Ce champ résulte de la dualisation de la condition d'égalité entre la pression de pore et de la pression de fluide au niveau des parois de la fracture. Afin de respecter les contraintes liées à XFEM, nous avons choisi d'introduire dans la formulation une loi cohésive non-régularisée de type Talon-Curnier. Ce type de loi est capable de gérer la propagation et/ou la refermeture de la fracture. Le modèle HM-XFEM a été validé à partir des solutions analytiques du modèle 2D de fracture KGD, et ce, pour différents régimes de propagation. Nous avons ensuite appliqué le modèle HM-XFEM au cas d'un réseau de fractures non connectées entre elles et évoluant sur des chemins de propagation prédéfinis, afin d'analyser comment les fractures d'un réseau peuvent influer les unes sur les autres lorsqu'elles sont soumises à un écoulement. En particulier, une étude paramétrique a été menée afin de montrer l'influence que peuvent avoir la viscosité, le débit d'injection et l'écartement entre les fractures sur leur propagation. Une attention particulière sera porté à l'évolution du stress-shadowing effect (i.e. modification de l'état de contrainte due à l'effet d'interaction entre les fractures).
- Published
- 2016
46. Modélisation du comportement hydrogéomécanique d’un réseau de failles sous l’effet des variations de l’état de contrainte
- Author
-
Faivre, Maxime, GeoRessources, Centre National de la Recherche Scientifique (CNRS)-Université de Lorraine (UL)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Institut national des sciences de l'Univers (INSU - CNRS), Université de Lorraine, Fabrice Golfier, Richard Giot, and ANR-10-LABX-0021,RESSOURCES21,Strategic metal resources of the 21st century(2010)
- Subjects
XFEM method ,Fracturation hydraulique ,Rupture ,[SPI.OTHER]Engineering Sciences [physics]/Other ,Matériaux poreux -- Fluides ,non-regularized cohesive constitutive law ,Dynamique des ,Réseau de fractures hydrauliques ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,fluid-driven fracture network ,Contraintes (mécanique) ,Méthode XFEM ,Mécanique de la rupture ,stress-shadowing effect ,fluid circulation ,fracture mechanics ,Loi cohésive non-régularisée ,Circulation de fluide ,KGD ,Failles (géologie) ,Mécanique de la - Abstract
In the present work, we address the issue of groundwater flow in the fractured porous media submitted to local or regional stress-state variations. Due to the increasing pore fluid pressure, the length and aperture distribution of the fractures are modified resulting in the formation of preferential flow channels within the geological formation. The numerical approach proposed is a fully coupled hydro-poro-mechanical model in saturated conditions involving single-phase flow both in fractures and in the porous matrix. The extended finite element method (XFEM) is employed for modeling fracture dynamics and flow calculation for fracture which do not lie on the mesh but cross through the elements. In this study: (i) we consider the pressure build up generated by fluid flow inside and through the fracture, (ii) the fracture dynamics by using a cohesive zone model (CZM) on pre-existing propagation path and (iii) fluid exchanges may occur in between fractures and porous medium. The last specification of the HM-XFEM model is taken into account through the introduction of a Lagrange multiplier field along the fracture path. These fields are the result of the dualised condition of pressure continuity between the pore pressure and the fluid pressure inside the fracture. As a function of the Lagrange multiplier value, both permeable and impervious fractures can be considered. The cohesive law employed is a non-regularized-type cohesive law to ensure propagation and eventually closure of the fracture. Validation of the model has been conducted by means of the well-known KGD fracture model when different propagation regimes are considered. We applied the HM-XFEM model to the case of multi-stage fracture network stimulated by the injection of incompressible fluid at constant rate. Fractures are not connected to each other and evolve on pre-existing propagation paths. We aim at appreciating the influence of the fluid viscosity, the injection rate and spacing between each fracture, on the fracture propagation. A peculiar attention is paid to the stress-shadowing effect (i.e. interaction between fractures).; Nous présentons dans ce mémoire l'influence que peuvent avoir les écoulements de fluide au sein de la matrice rocheuse fracturée, laquelle est sujette aux variations locales ou régionales de l'état de contrainte in situ. Du fait de l'augmentation de la pression de pore, la longueur et l'ouverture de la (les) fracture(s) peuvent subir des variations significatives et conduire à la formation de chemins préférentiels pour l'écoulement du fluide dans le milieu géologique. Les modèles théorique et numérique évoqués ici sont des modèles de comportement hydro-mécanique pour le milieu poreux saturé en présence d'une seule phase fluide. La méthode des éléments finis étendue (XFEM) est utilisée afin de modéliser la dynamique des fractures ainsi que les écoulements de fluide dans la matrice rocheuse fracturée, sans être tributaire de la dépendance au maillage. Ainsi, nous considérons: (i) qu'il existe une pression fluide induite par l'écoulement au sein de la fracture, (ii) que la dynamique de la fracture est gérée grâce à un modèle de zone cohésive en supposant un chemin de propagation prédéfini, et (iii) que des échanges entre la fracture et la matrice poreuse peuvent se produire. Ce dernier aspect sera pris en compte en introduisant, dans la formulation du problème couplé, un champ de multiplicateur de Lagrange. Ce champ résulte de la dualisation de la condition d'égalité entre la pression de pore et de la pression de fluide au niveau des parois de la fracture. Afin de respecter les contraintes liées à XFEM, nous avons choisi d'introduire dans la formulation une loi cohésive non-régularisée de type Talon-Curnier. Ce type de loi est capable de gérer la propagation et/ou la refermeture de la fracture. Le modèle HM-XFEM a été validé à partir des solutions analytiques du modèle 2D de fracture KGD, et ce, pour différents régimes de propagation. Nous avons ensuite appliqué le modèle HM-XFEM au cas d'un réseau de fractures non connectées entre elles et évoluant sur des chemins de propagation prédéfinis, afin d'analyser comment les fractures d'un réseau peuvent influer les unes sur les autres lorsqu'elles sont soumises à un écoulement. En particulier, une étude paramétrique a été menée afin de montrer l'influence que peuvent avoir la viscosité, le débit d'injection et l'écartement entre les fractures sur leur propagation. Une attention particulière sera porté à l'évolution du stress-shadowing effect (i.e. modification de l'état de contrainte due à l'effet d'interaction entre les fractures).
- Published
- 2016
47. Influence of temperature on the rate-independent and rate-dependent behaviours of geomaterials and underground excavations
- Author
-
Raude, Simon, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, Richard Giot, and UL, Thèses
- Subjects
[SPI.OTHER]Engineering Sciences [physics]/Other ,Thermo-plasticity/viscoplasticity ,[SPI.OTHER] Engineering Sciences [physics]/Other ,Géomatériaux-Effets de la température ,Geomaterials ,Comportement thermomécanique ,Constitutive model ,Géomatériaux ,Thermo-plasticité/viscoplasticité ,Code_Aster ,Géomatériaux-Propriétés thermomécaniques ,Modèle de comportement ,Viscoplasticité ,Thermomechanical behaviour - Abstract
The effect of temperature on the behaviour of geomaterials is a crucial issue in geotechnical and underground engineering. The thermo-mechanical behaviour of rocks and soils contains many applications in the fields of high-level nuclear waste disposal, heat storage, geothermal structures, petroleum drilling, zones around buried high-voltage cables, bituminous materials, and geological research. In the context of nuclear waste disposal at great depths, the thermo-mechanical behaviour of Boom clay, Opalinus clay, Callovo-Oxfordian argillite and Äspö diorite has recently received special attention in Europe. Research in these areas has demonstrated that rocks and soils may suffer from changes in their mechanical properties during short-to long-term exposure to an elevated temperature. These changes include effects on the friction angle, permeability/porosity, elastic moduli, shear strength, dilatancy, softening, brittle-to-ductile transition, creep, etc... Since Prager's first works on the modelling of non-isothermal plastic deformation, many constitutive models have been developed to include these phenomena in computational inelasticity. Most models generalize the critical-state model to include the effects of temperature on the short-term behaviour of clays and rocks. However, the effect of time on the thermo-mechanical behaviour is often not coupled to the rate-independent plasticity even if the long-term behaviour appears essential for ensuring the safety and stability during the design and construction analysis in many fields, such as the storage of nuclear waste and more generally underground excavations. Thus, it appears important to combine both instantaneous and delayed thermo-mechanical effects to obtain appropriate constitutive equations to model such problems. In this Ph.D thesis, a unified thermo-plastic/viscoplastic constitutive model has been developed for this purpose. This model is a straightforward extension of the unified elasto-plastic/viscoplastic L&K constitutive model which was developed in previous Ph.D works. The updated thermo-mechanical model includes the evolutions of the two yield limits and the fluidity coefficient with temperature. The model was validated under several thermo-mechanical conditions on clayey rocks. The typical features of the thermo-mechanical behaviour of geomaterials were well reproduced. The numerical predictions of the triaxial compression tests and creep tests clearly indicate that the model can predict the overall behaviour of geomaterials under deviatoric and non-isothermal stress paths, Le comportement thermomécanique des géomatériaux est un sujet de recherche qui touche un nombre important de domaines d'application : le stockage des déchets radioactifs en couche géologique profonde, le comportement des structures géothermiques, le stockage de chaleur, le comportement des matériaux à proximité des câbles à haute tension, le comportement saisonnier des matériaux asphaltiques, l'origine des tremblements de terre, etc. Dans le contexte du stockage des déchets radioactifs en couches géologiques profondes, un intérêt particulier a récemment été accordé à l'étude du comportement thermomécanique de l'argile de Boom, l'argile à Opalines, l'argilite du Callovo-Oxfordien et la diorite d'Äspö. L'ensemble de ces études montre qu'une exposition à des températures élevées peut altérer les propriétés physiques et mécaniques des géomatériaux : l'angle de frottement, la cohésion, la perméabilité-porosité, les modules élastiques, la résistance, le comportement volumique, le comportement post-pic, le comportement à long terme, etc. Depuis une trentaine d'années, un nombre important de modèles de comportement ont été développés dans le but d'intégrer les effets de la température à des modèles élasto-plastiques dérivés de la théorie de l'état critique. Cependant, peu de ces modèles intègrent les effets du temps sur le comportement thermomécanique des géomatériaux ; lequel apparaît essentiel au dimensionnement de structures à long terme. L'objectif de ces travaux de thèse est de répondre à cette problématique en intégrant les effets de la température au modèle de comportement mécanique L&K. Le modèle de comportement L&K est un modèle à deux mécanismes, l'un dit "plastique" permettant de décrire le comportement mécanique instantané des matériaux, l'autre dit "viscoplastique" permettant de décrire le comportement différé. Après un état des lieux détaillé concernant les comportements thermomécaniques instantané et différé des géomatériaux, les effets de la température ont été pris en compte à travers l'évolution des paramètres d'écrouissage des deux mécanismes. Ce modèle thermomécanique a été validé sur des applications expérimentales en support de ce travail de thèse. Les résultats montrent que la formulation proposée permet de reproduire fidèlement le comportement thermomécanique des géomatériaux. Les applications à venir concernent des calculs sur ouvrage dans le contexte du stockage des déchets radioactifs
- Published
- 2015
48. Prise en compte des sollicitations thermiques sur les comportements instantané et différé des géomatériaux
- Author
-
Raude, Simon, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, and Richard Giot
- Subjects
Thermo-plasticité/viscoplasticité ,[SPI.OTHER]Engineering Sciences [physics]/Other ,Thermo-plasticity/viscoplasticity ,Géomatériaux-Effets de la température ,Code_Aster ,Geomaterials ,Comportement thermomécanique ,Constitutive model ,Géomatériaux-Propriétés thermomécaniques ,Modèle de comportement ,Viscoplasticité ,Thermomechanical behaviour ,Géomatériaux - Abstract
The effect of temperature on the behaviour of geomaterials is a crucial issue in geotechnical and underground engineering. The thermo-mechanical behaviour of rocks and soils contains many applications in the fields of high-level nuclear waste disposal, heat storage, geothermal structures, petroleum drilling, zones around buried high-voltage cables, bituminous materials, and geological research. In the context of nuclear waste disposal at great depths, the thermo-mechanical behaviour of Boom clay, Opalinus clay, Callovo-Oxfordian argillite and Äspö diorite has recently received special attention in Europe. Research in these areas has demonstrated that rocks and soils may suffer from changes in their mechanical properties during short-to long-term exposure to an elevated temperature. These changes include effects on the friction angle, permeability/porosity, elastic moduli, shear strength, dilatancy, softening, brittle-to-ductile transition, creep, etc... Since Prager's first works on the modelling of non-isothermal plastic deformation, many constitutive models have been developed to include these phenomena in computational inelasticity. Most models generalize the critical-state model to include the effects of temperature on the short-term behaviour of clays and rocks. However, the effect of time on the thermo-mechanical behaviour is often not coupled to the rate-independent plasticity even if the long-term behaviour appears essential for ensuring the safety and stability during the design and construction analysis in many fields, such as the storage of nuclear waste and more generally underground excavations. Thus, it appears important to combine both instantaneous and delayed thermo-mechanical effects to obtain appropriate constitutive equations to model such problems. In this Ph.D thesis, a unified thermo-plastic/viscoplastic constitutive model has been developed for this purpose. This model is a straightforward extension of the unified elasto-plastic/viscoplastic L&K constitutive model which was developed in previous Ph.D works. The updated thermo-mechanical model includes the evolutions of the two yield limits and the fluidity coefficient with temperature. The model was validated under several thermo-mechanical conditions on clayey rocks. The typical features of the thermo-mechanical behaviour of geomaterials were well reproduced. The numerical predictions of the triaxial compression tests and creep tests clearly indicate that the model can predict the overall behaviour of geomaterials under deviatoric and non-isothermal stress paths; Le comportement thermomécanique des géomatériaux est un sujet de recherche qui touche un nombre important de domaines d'application : le stockage des déchets radioactifs en couche géologique profonde, le comportement des structures géothermiques, le stockage de chaleur, le comportement des matériaux à proximité des câbles à haute tension, le comportement saisonnier des matériaux asphaltiques, l'origine des tremblements de terre, etc. Dans le contexte du stockage des déchets radioactifs en couches géologiques profondes, un intérêt particulier a récemment été accordé à l'étude du comportement thermomécanique de l'argile de Boom, l'argile à Opalines, l'argilite du Callovo-Oxfordien et la diorite d'Äspö. L'ensemble de ces études montre qu'une exposition à des températures élevées peut altérer les propriétés physiques et mécaniques des géomatériaux : l'angle de frottement, la cohésion, la perméabilité-porosité, les modules élastiques, la résistance, le comportement volumique, le comportement post-pic, le comportement à long terme, etc. Depuis une trentaine d'années, un nombre important de modèles de comportement ont été développés dans le but d'intégrer les effets de la température à des modèles élasto-plastiques dérivés de la théorie de l'état critique. Cependant, peu de ces modèles intègrent les effets du temps sur le comportement thermomécanique des géomatériaux ; lequel apparaît essentiel au dimensionnement de structures à long terme. L'objectif de ces travaux de thèse est de répondre à cette problématique en intégrant les effets de la température au modèle de comportement mécanique L&K. Le modèle de comportement L&K est un modèle à deux mécanismes, l'un dit "plastique" permettant de décrire le comportement mécanique instantané des matériaux, l'autre dit "viscoplastique" permettant de décrire le comportement différé. Après un état des lieux détaillé concernant les comportements thermomécaniques instantané et différé des géomatériaux, les effets de la température ont été pris en compte à travers l'évolution des paramètres d'écrouissage des deux mécanismes. Ce modèle thermomécanique a été validé sur des applications expérimentales en support de ce travail de thèse. Les résultats montrent que la formulation proposée permet de reproduire fidèlement le comportement thermomécanique des géomatériaux. Les applications à venir concernent des calculs sur ouvrage dans le contexte du stockage des déchets radioactifs
- Published
- 2015
49. Modelling of chemo-poromechanical coupling applied to the CO2 storage in coal
- Author
-
Saliya, Kanssoune, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, Albert Giraud, Richard Giot, and Dragan Grgic
- Subjects
[SPI.OTHER]Engineering Sciences [physics]/Other ,Isotherme de Langmuir ,Matériaux poreux-Propriétés physico-chimiques ,Propriétés Hydro-Mécaniques ,Methane recovery ,CO2 injection ,Perméabilité intrinsèque ,Porosité ,Intrinsic permeability ,Charbon-Perméabilité ,Langmuir’s isotherm ,Injection de CO2 ,Coal ,Numerical modelling ,Charbon ,HYTEC ,Code_Aster ,Captage et stockage géologique du dioxyde de carbone ,Récupération de méthane ,Modélisation numérique ,Porosity ,Hydro-mechanical properties - Abstract
Accès restreint aux membres de l'Université de Lorraine jusqu'au 2016-09-04; The geological storage of CO2 in aquifers reservoirs such as limestone and sandstone, coal is a possible way to reduce greenhouse gas emission into the atmosphere. However, the injection of CO2 may modify petrophysical (porosity and permeability), mineralogical (transformations) and mechanical (deformations, strength) properties of reservoir rocks (limestone, sandstone, coal). In the case of coal, the injection of CO2 can also induce matrix swelling due to adsorption processes. The focus of this thesis is to translate in terms of phenomenological models, the behaviors and chemo-poromechanical coupling of reservoir rocks of coal type. In this work, we focused particularly on the study of CO2 injection into coal. For this, two models of homogenized coal porosity have been developed by taking into account the adsorption phenomenon, known to be the main mechanism of production or sequestration of CO2 in many coal reservoirs. The first model allows the study of the poroelastic behavior of coal in the case of a single injection of CO2, and the second model allows the study of the poroelastic behavior of coal in the case of an injection of CO2 with methane CH4 recovery. The adsorption process is classically modelled using Langmuir’s isotherm (for one gas in the first model and for two gases in the second model). The implementation of these models in Code_Aster (a fully coupled Thermo-Hydro-Mechanical analysis code for structures calculations, developed by Electricity of France - EDF) allowed us to make numerical simulations of CO2 storage in coal. For a single injection of CO2 into coal (first model), the coal matrix behaved in two different ways: it swells (resulting in the decrease of coal porosity) when the adsorption phenomenon is taken into account and shrinks (resulting in the increase of coal porosity) otherwise. Being in good agreement with the results in specialized literature in this field, it shows the ability of the model to predict the poroelastic behaviour of coal to CO2 injection. Also with the first model, we studied particularly through numerical simulations the influence of coal’s hydro-mechanical properties (Biot’s coefficient, bulk modulus), Langmuir’s adsorption parameters and the initial liquid pressure in rock mass during CO2 injection in coal. In the case of methane recovery (second model), a coupling of Code_Aster and a reactive transport code, HYTEC (Hydrological Transport coupled with Equilibrium Chemistry, developed by Mines Paris Tech) was needed to handle the above calculation of partial pressures of the two gases (CO2 and CH4) at each time step. Digital development work on the two computers codes (Code_Aster and HYTEC) was then necessary. This thesis proposed a method of coupling between the two codes whose techniques are widely described in the manuscript.; Le stockage géologique du CO2 dans des réservoirs aquifères de type calcaire et grès, du charbon non exploité est une des solutions envisagées pour réduire les émissions de gaz à effet de serre dans l’atmosphère. Cependant, l’injection de CO2 peut perturber les propriétés pétrophysiques (porosité et perméabilité), minéralogiques (transformations) et mécaniques (déformations, résistance à la rupture) des roches réservoir (calcaire, grès, charbon). Dans le cas du charbon, l’injection de CO2 peut également se traduire par des phénomènes de gonflement de la matrice liés au processus d’adsorption. L’objectif de ce travail de thèse est de traduire en termes de modèles phénoménologiques les comportements et les couplages chimio-poromécaniques des roches réservoir de type charbon. Dans ce travail, nous nous sommes focalisés en particulier sur l’étude de l’injection de CO2 dans le charbon. Pour cela, deux modèles homogénéisés de porosité du charbon ont été développés avec la prise en compte du phénomène d’adsorption, connu pour être le principal mécanisme de production ou de séquestration de CO2 dans de nombreux réservoir de charbon. Le premier modèle permet d’étudier le comportement poro-élastique du charbon pour une injection simple de CO2 et le second permet d’étudier le comportement poro-élastique du charbon pour une injection de CO2 avec une récupération assistée de méthane CH4. Le processus d’adsorption est classiquement modélisé à l’aide de l’isotherme d’adsorption de Langmuir (pour un gaz dans le premier modèle et pour deux gaz dans le second modèle). L’implantation de ces modèles dans le Code_Aster (code d’analyse de calcul de structures entièrement couplé THM, développé par Electricité De France - EDF) nous a permis de faire des simulations numériques de stockage de CO2 dans le charbon. Pour une injection simple du CO2 dans le charbon (premier modèle), la matrice du charbon s’est comportée de deux façons différentes : elle gonfle (ce qui induit une diminution de la porosité du charbon) avec la prise en compte du phénomène d’adsorption et se contracte (ce qui induit une augmentation de la porosité du charbon) dans le cas contraire. Etant en bon accord avec les résultats de la littérature spécialisée, cela montre la capacité du modèle à prédire le comportement poro-élastique du charbon durant l’injection de CO2. Toujours avec le premier modèle, nous avons en particulier étudié l’influence des propriétés hydro-mécaniques du charbon (coefficient de Biot, module de Young/module d’incompressibilité), les paramètres d’adsorption de Langmuir et la pression initiale du liquide interstitiel dans le charbon, sur la réponse du charbon à l’injection du CO2. Dans le cas d’une récupération assistée du méthane CH4 (le second modèle), un couplage du Code_Aster et un code de transport réactif HYTEC (HYdrological Transport coupled with Equilibrium Chemistry, développé par MINES Paris Tech) était nécessaire pour gérer surtout le calcul des pressions partielles des deux gaz (CO2 et CH4) à chaque pas de temps. Un travail de développement numérique sur les deux codes de calcul était alors nécessaire. Ce travail de thèse a proposé une méthode de couplage entre les deux codes (Code_Aster et HYTEC) dont les techniques sont largement décrites dans le manuscrit.
- Published
- 2014
50. Modélisation des couplages chimio-poromécaniques appliquée au stockage de CO2 dans le charbon
- Author
-
Saliya, Kanssoune, GeoRessources, Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine, Albert Giraud, Richard Giot, and Dragan Grgic
- Subjects
[SPI.OTHER]Engineering Sciences [physics]/Other ,Isotherme de Langmuir ,Matériaux poreux-Propriétés physico-chimiques ,Propriétés Hydro-Mécaniques ,Methane recovery ,CO2 injection ,Perméabilité intrinsèque ,Porosité ,Intrinsic permeability ,Charbon-Perméabilité ,Langmuir’s isotherm ,Injection de CO2 ,Coal ,Numerical modelling ,Charbon ,HYTEC ,Code_Aster ,Captage et stockage géologique du dioxyde de carbone ,Récupération de méthane ,Modélisation numérique ,Porosity ,Hydro-mechanical properties - Abstract
Accès restreint aux membres de l'Université de Lorraine jusqu'au 2016-09-04; The geological storage of CO2 in aquifers reservoirs such as limestone and sandstone, coal is a possible way to reduce greenhouse gas emission into the atmosphere. However, the injection of CO2 may modify petrophysical (porosity and permeability), mineralogical (transformations) and mechanical (deformations, strength) properties of reservoir rocks (limestone, sandstone, coal). In the case of coal, the injection of CO2 can also induce matrix swelling due to adsorption processes. The focus of this thesis is to translate in terms of phenomenological models, the behaviors and chemo-poromechanical coupling of reservoir rocks of coal type. In this work, we focused particularly on the study of CO2 injection into coal. For this, two models of homogenized coal porosity have been developed by taking into account the adsorption phenomenon, known to be the main mechanism of production or sequestration of CO2 in many coal reservoirs. The first model allows the study of the poroelastic behavior of coal in the case of a single injection of CO2, and the second model allows the study of the poroelastic behavior of coal in the case of an injection of CO2 with methane CH4 recovery. The adsorption process is classically modelled using Langmuir’s isotherm (for one gas in the first model and for two gases in the second model). The implementation of these models in Code_Aster (a fully coupled Thermo-Hydro-Mechanical analysis code for structures calculations, developed by Electricity of France - EDF) allowed us to make numerical simulations of CO2 storage in coal. For a single injection of CO2 into coal (first model), the coal matrix behaved in two different ways: it swells (resulting in the decrease of coal porosity) when the adsorption phenomenon is taken into account and shrinks (resulting in the increase of coal porosity) otherwise. Being in good agreement with the results in specialized literature in this field, it shows the ability of the model to predict the poroelastic behaviour of coal to CO2 injection. Also with the first model, we studied particularly through numerical simulations the influence of coal’s hydro-mechanical properties (Biot’s coefficient, bulk modulus), Langmuir’s adsorption parameters and the initial liquid pressure in rock mass during CO2 injection in coal. In the case of methane recovery (second model), a coupling of Code_Aster and a reactive transport code, HYTEC (Hydrological Transport coupled with Equilibrium Chemistry, developed by Mines Paris Tech) was needed to handle the above calculation of partial pressures of the two gases (CO2 and CH4) at each time step. Digital development work on the two computers codes (Code_Aster and HYTEC) was then necessary. This thesis proposed a method of coupling between the two codes whose techniques are widely described in the manuscript.; Le stockage géologique du CO2 dans des réservoirs aquifères de type calcaire et grès, du charbon non exploité est une des solutions envisagées pour réduire les émissions de gaz à effet de serre dans l’atmosphère. Cependant, l’injection de CO2 peut perturber les propriétés pétrophysiques (porosité et perméabilité), minéralogiques (transformations) et mécaniques (déformations, résistance à la rupture) des roches réservoir (calcaire, grès, charbon). Dans le cas du charbon, l’injection de CO2 peut également se traduire par des phénomènes de gonflement de la matrice liés au processus d’adsorption. L’objectif de ce travail de thèse est de traduire en termes de modèles phénoménologiques les comportements et les couplages chimio-poromécaniques des roches réservoir de type charbon. Dans ce travail, nous nous sommes focalisés en particulier sur l’étude de l’injection de CO2 dans le charbon. Pour cela, deux modèles homogénéisés de porosité du charbon ont été développés avec la prise en compte du phénomène d’adsorption, connu pour être le principal mécanisme de production ou de séquestration de CO2 dans de nombreux réservoir de charbon. Le premier modèle permet d’étudier le comportement poro-élastique du charbon pour une injection simple de CO2 et le second permet d’étudier le comportement poro-élastique du charbon pour une injection de CO2 avec une récupération assistée de méthane CH4. Le processus d’adsorption est classiquement modélisé à l’aide de l’isotherme d’adsorption de Langmuir (pour un gaz dans le premier modèle et pour deux gaz dans le second modèle). L’implantation de ces modèles dans le Code_Aster (code d’analyse de calcul de structures entièrement couplé THM, développé par Electricité De France - EDF) nous a permis de faire des simulations numériques de stockage de CO2 dans le charbon. Pour une injection simple du CO2 dans le charbon (premier modèle), la matrice du charbon s’est comportée de deux façons différentes : elle gonfle (ce qui induit une diminution de la porosité du charbon) avec la prise en compte du phénomène d’adsorption et se contracte (ce qui induit une augmentation de la porosité du charbon) dans le cas contraire. Etant en bon accord avec les résultats de la littérature spécialisée, cela montre la capacité du modèle à prédire le comportement poro-élastique du charbon durant l’injection de CO2. Toujours avec le premier modèle, nous avons en particulier étudié l’influence des propriétés hydro-mécaniques du charbon (coefficient de Biot, module de Young/module d’incompressibilité), les paramètres d’adsorption de Langmuir et la pression initiale du liquide interstitiel dans le charbon, sur la réponse du charbon à l’injection du CO2. Dans le cas d’une récupération assistée du méthane CH4 (le second modèle), un couplage du Code_Aster et un code de transport réactif HYTEC (HYdrological Transport coupled with Equilibrium Chemistry, développé par MINES Paris Tech) était nécessaire pour gérer surtout le calcul des pressions partielles des deux gaz (CO2 et CH4) à chaque pas de temps. Un travail de développement numérique sur les deux codes de calcul était alors nécessaire. Ce travail de thèse a proposé une méthode de couplage entre les deux codes (Code_Aster et HYTEC) dont les techniques sont largement décrites dans le manuscrit.
- Published
- 2014
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