Géothermie profonde (stimulation de la perméabilité par fracturation hydraulique dans un cadre thermo-poroélastique)

Ce travail concerne l'utilisation de la technique de Fracturation Hydraulique (FH) pour exploiter l'énergie géothermique des réservoirs profonds de roches sèches chaudes (HDR). La fracturation hydraulique est réalisée par injection de fluides géothermiques dans des réservoirs partiellement fracturés de faible perméabilité. Les fluides à haute pression sont destinés à faire évoluer les fissures et leur connectivité. Les valeurs de débit/pression auxquelles les fluides géothermiques doivent être pompés, ainsi que le calendrier de pompage pour initier la fracturation hydraulique, dépendent principalement des conditions géostatiques existantes (contraintes géostatiques, pression fluide et température initiales de l'HDR) ainsi que des propriétés des fissures de l'HDR (longueur, épaisseur, densité et distribution directionnelle initiales moyennes de fissures). Tous ces éléments, en sus de leurs effets sur la stabilité des forages, sont analysés dans cette recherche. Des modèles de fracturation, qui sont capables de suivre l'évolution des fissures dans toutes les orientations spatiales possibles, sont utilisés pour obtenir le tenseur anisotrope de perméabilité. Ces modèles sont intégrés dans un code domestique d'éléments finis qui est développé pour résoudre des problèmes aux limites thermo-poroélastiques. Pour supprimer/diminuer les oscillations qui accompagnent les solutions paraboliques et/ou hyperboliques lors de la convection forcée, plusieurs techniques de stabilisation ont dû être implémentées.The application of the Hydraulic Fracturing (HF) technology to exploit geothermal energy from Hot Dry Rocks (HDR) reservoirs is addressed. HF is achieved by extensively pumping geothermal fluids to already existing fractured HDR reservoirs of low permeability. High fluid pressures are expected to drive cracks to evolve and connect. The newly created burgeoning hydraulic conduits should supposedly enhance the permeability of the existing HDR reservoirs. The flow rate/pressure values at which geothermal fluids should be pumped, as well as the pumping schedule to initiate HF, depend primarily on the existing geostatic conditions (geostatic stresses, initial HDR pressure and temperature) as well as on HDR fracture properties (initial mean fracture length, mean fracture aperture, density and orientational distribution of fractures). While these components, in addition to their effects on borehole stability, are scrutinized in this research, focus is on the evolution during circulation processes of the fracture properties. A fracturing model that is capable of tracking fracture evolution in all possible spatial orientations is used to obtain the time course of the anisotropic permeability tensor. This evolving property is integrated into a domestic finite element code which is developed to solve thermo poroelastic BVPs: emphasis is laid on the efficiency of the doublet flow technique where a fluid gains thermal energy by circulating through the HDR reservoir from the injection well to the production well. The spurious oscillations in the hyperbolic solutions of the approximated finite element approach that are commensal with the phenomenon of forced heat convection are healed/mitigated through several stabilization approaches.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Enhanced geothermal systems : permeability enhancement through hydraulic fracturing in a poro-thermoelastic framework

Ce travail concerne l'utilisation de la technique de Fracturation Hydraulique (FH) pour exploiter l'énergie géothermique des réservoirs profonds de roches sèches chaudes (HDR). La fracturation hydraulique est réalisée par injection de fluides géothermiques dans des réservoirs partiellement fracturés de faible perméabilité. Les fluides à haute pression sont destinés à faire évoluer les fissures et leur connectivité. Les valeurs de débit/pression auxquelles les fluides géothermiques doivent être pompés, ainsi que le calendrier de pompage pour initier la fracturation hydraulique, dépendent principalement des conditions géostatiques existantes (contraintes géostatiques, pression fluide et température initiales de l'HDR) ainsi que des propriétés des fissures de l'HDR (longueur, épaisseur, densité et distribution directionnelle initiales moyennes de fissures). Tous ces éléments, en sus de leurs effets sur la stabilité des forages, sont analysés dans cette recherche. Des modèles de fracturation, qui sont capables de suivre l'évolution des fissures dans toutes les orientations spatiales possibles, sont utilisés pour obtenir le tenseur anisotrope de perméabilité. Ces modèles sont intégrés dans un code domestique d'éléments finis qui est développé pour résoudre des problèmes aux limites thermo-poroélastiques. Pour supprimer/diminuer les oscillations qui accompagnent les solutions paraboliques et/ou hyperboliques lors de la convection forcée, plusieurs techniques de stabilisation ont dû être implémentées.The application of the Hydraulic Fracturing (HF) technology to exploit geothermal energy from Hot Dry Rocks (HDR) reservoirs is addressed. HF is achieved by extensively pumping geothermal fluids to already existing fractured HDR reservoirs of low permeability. High fluid pressures are expected to drive cracks to evolve and connect. The newly created burgeoning hydraulic conduits should supposedly enhance the permeability of the existing HDR reservoirs. The flow rate/pressure values at which geothermal fluids should be pumped, as well as the pumping schedule to initiate HF, depend primarily on the existing geostatic conditions (geostatic stresses, initial HDR pressure and temperature) as well as on HDR fracture properties (initial mean fracture length, mean fracture aperture, density and orientational distribution of fractures). While these components, in addition to their effects on borehole stability, are scrutinized in this research, focus is on the evolution during circulation processes of the fracture properties. A fracturing model that is capable of tracking fracture evolution in all possible spatial orientations is used to obtain the time course of the anisotropic permeability tensor. This evolving property is integrated into a domestic finite element code which is developed to solve thermo–poroelastic BVPs: emphasis is laid on the efficiency of the doublet flow technique where a fluid gains thermal energy by circulating through the HDR reservoir from the injection well to the production well. The spurious oscillations in the hyperbolic solutions of the approximated finite element approach that are commensal with the phenomenon of forced heat convection are healed/mitigated through several stabilization approaches

Geothermal Reservoir Stimulation Using The Finite Element Method

International audienc

Géothermie profonde : stimulation de la perméabilité par fracturation hydraulique dans un cadre thermo-poroélastique

The application of the Hydraulic Fracturing (HF) technology to exploit geothermal energy from Hot Dry Rocks (HDR) reservoirs is addressed. HF is achieved by extensively pumping geothermal fluids to already existing fractured HDR reservoirs of low permeability. High fluid pressures are expected to drive cracks to evolve and connect. The newly created burgeoning hydraulic conduits should supposedly enhance the permeability of the existing HDR reservoirs. The flow rate/pressure values at which geothermal fluids should be pumped, as well as the pumping schedule to initiate HF, depend primarily on the existing geostatic conditions (geostatic stresses, initial HDR pressure and temperature) as well as on HDR fracture properties (initial mean fracture length, mean fracture aperture, density and orientational distribution of fractures). While these components, in addition to their effects on borehole stability, are scrutinized in this research, focus is on the evolution during circulation processes of the fracture properties. A fracturing model that is capable of tracking fracture evolution in all possible spatial orientations is used to obtain the time course of the anisotropic permeability tensor. This evolving property is integrated into a domestic finite element code which is developed to solve thermo–poroelastic BVPs: emphasis is laid on the efficiency of the doublet flow technique where a fluid gains thermal energy by circulating through the HDR reservoir from the injection well to the production well. The spurious oscillations in the hyperbolic solutions of the approximated finite element approach that are commensal with the phenomenon of forced heat convection are healed/mitigated through several stabilization approaches.Ce travail concerne l'utilisation de la technique de Fracturation Hydraulique (FH) pour exploiter l'énergie géothermique des réservoirs profonds de roches sèches chaudes (HDR). La fracturation hydraulique est réalisée par injection de fluides géothermiques dans des réservoirs partiellement fracturés de faible perméabilité. Les fluides à haute pression sont destinés à faire évoluer les fissures et leur connectivité. Les valeurs de débit/pression auxquelles les fluides géothermiques doivent être pompés, ainsi que le calendrier de pompage pour initier la fracturation hydraulique, dépendent principalement des conditions géostatiques existantes (contraintes géostatiques, pression fluide et température initiales de l'HDR) ainsi que des propriétés des fissures de l'HDR (longueur, épaisseur, densité et distribution directionnelle initiales moyennes de fissures). Tous ces éléments, en sus de leurs effets sur la stabilité des forages, sont analysés dans cette recherche. Des modèles de fracturation, qui sont capables de suivre l'évolution des fissures dans toutes les orientations spatiales possibles, sont utilisés pour obtenir le tenseur anisotrope de perméabilité. Ces modèles sont intégrés dans un code domestique d'éléments finis qui est développé pour résoudre des problèmes aux limites thermo-poroélastiques. Pour supprimer/diminuer les oscillations qui accompagnent les solutions paraboliques et/ou hyperboliques lors de la convection forcée, plusieurs techniques de stabilisation ont dû être implémentées

Energy Features of Underground Exploitation by Fluid Circulation

This work presents the geomechanical and thermodynamic aspects related to the problem of exploiting underground energy resources by fluid circulation. The first chapter discusses the thermodynamics of continuous media. The two frameworks of thermodynamics of isotropic fluid mixtures and thermodynamics of multiphase compositional flows in porous media are briefly pointed out. The second chapter treats the problem of hydraulic stimulation of deep geothermal reservoirs. While considering a continuum approach, it investigates hydraulic fracturing effects on impedance and efficiency of thermal recovery from these reservoirs. The chapter continues to scrutinize the technique of hydraulic fracturing, particularly the fluid-injection related induced seismicity. In a continuum-discontinuum framework, it provides a strategy to relate induced seismicity to non-diffusive triggering fronts that encompass most of the seismic cloud.Since renewable energy is limited to its intermittent nature, this research introduces gas storage in salt caverns as a large-scale storing technique. The increasing energy demands will, however, necessitate frequent utilization of these caverns. The fast cycling, and its subsequent severe mechanical and thermal charges, impose challenges regarding the thermodynamic state within the cavern, and the masses exchanged between the cavern phases. To have precise tracks of cycled gas quantities and to master losses, these challenges have to be considered. This work validates the mathematical models at the laboratory scale, and provides transferring techniques to real-scale applications. Each section provides a precise introduction concerning the discussedproblem, and terminates by a conclusion. A general introduction and a review and perspectives are also furnished

Enhanced Geothermal Systems (EGS): Permeability Stimulation Through Hydraulic Fracturing in a Thermo-Poroelastic Framework

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Hydraulic fracturing for geothermal and petroleum applications: continuum/discontinuum approaches

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Permeability enhancement of HDR reservoirs by hydraulic fracturing

International audienceThe permeability of geothermal reservoirs needs to be enhanced. Hydraulic Fracturing (HF) is the standard tool used for that purpose. Here HF is introduced in a thermo-poroelastic framework. The main ingredient of the HF scheme is a fracturing model that governs the evolution of the size and width of the fractures. At any geometrical point, a fracture-induced anisotropic permeability tensor is calculated: next to the injection pressure, the directional properties of this tensor are strongly influenced by the geological stresses. This fracturing model is integrated into a domestic Fortran 90 finite element code. Circulation tests and thermal recovery from the enhanced geothermal reservoir of Soultz-Sous-Forêts are simulated

Is the hypothesis of a uniform thermodynamic state still valid in hydrogen underground caverns during fast cycling?

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