En France métropolitaine, les projets de géothermie haute température pour la production d’électricité sont principalement localisés dans le socle des fossés d’effondrement liés à la mise en place du Rift Ouest Européen. Le socle de ces fossés a été étudié sur deux analogues à l’affleurement sur les épaules du rift : les Vosges du Nord pour le fossé Rhénan et la bordure Est du Massif central pour la fosse de Valence. Cette étude a permis de montrer que le réseau de failles s’organise selon trois ordres de grandeurs de longueurs et d’espacements caractéristiques qui individualisent des blocs structuraux. Les orientations et l’espacement des failles formant ces blocs et la présence ou l’absence de certains ordres de grandeurs sont le résultat de l’héritage anté-rift du socle, ainsi que du mécanisme d’ouverture du bassin. Le potentiel réservoir des formations de socle et de la couverture surincombante a été analysé au regard de ces zones de failles et de l’altération supergène qui affecte le toit du socle. Ainsi, les lithologies potentiellement rencontrées en base des fossés ont pu être classées en fonction du potentiel de développement de porosité et de perméabilité matricielle dans les cœurs de failles, les zones endommagées et le réseau pervasif de fractures dans le protolithe. L’évolution de la fracturation dans les zones de failles a également pu être appréhendé, et une méthodologie de modélisation double milieu a été élaborée pour caractériser la porosité et la perméabilité de fractures et modéliser le fonctionnement d’un doublet géothermique dans une faille synthéthique équivalente aux cibles des projets géothermiques / High temperature geothermal projects for electricity production are in France mostly localized in the basement of basins linked to the West European Rifting event. The basement of theses basins have been studied on two outcrop analogues at the shoulders of the rift: the Northern Vosges mountains for the Upper Rhine Graben and the Eastern border of the Massif central for the Valence Graben. This study has shown that the fault network is organized in three orders of size with characteristic length and spacing, and that form characteristic structural blocks. The orientation and spacing of these faults and the presence or absence of some size orders are the result of structural inheritance of the basement and the mechanism of the basin opening. The reservoir potential of the basement rocks and the surrounding sedimentary cover has been analysed in light of the fault zones structure and the weathered layer at the top of the basement. Thus, the basement rocks of the basins has been classified in light of the potential of matrix porosity and permeability development in the fault core, the damaged zone and the fractured protolith. The evolution of the fracture network in the fault zone has been studied too, with the development of a double-porosity model in order to characterize the fracture porosity and permeability, and therefore simulate the working of a geothermal doublet in a synthethic fault zone analogue of the geothermal drilling targets

La zone de Vieux-Habitants rassemble les indices permettant de supposer la présence d’un système hydrothermal de haute température. Les données géophysiques acquises pour la prospection de ce système ne suffisent pas à sa compréhension qui nécessite l’analyse d’analogues. Pour proposer un modèle de système géothermique de cette zone, une analyse multiscalaire de la déformation fragile et une caractérisation des propriétés pétrophysiques des formations volcaniques ont été ménées sur trois paléo systèmes. L’analyse des populations de fractures montre que leur organisation n’est pas régie par une seule loi mathématique. Les faciès volcano-sédimentaires sont peu déformés ou de manière très localisée contrairement aux laves dont les densités de fracturation sont fortes. L’analyse de la distribution des faciès hydrothermalisés par rapport à ces structures indique qu’à l’échelle kilométrique, certaines intersections de failles contrôlent le drainage des fluides et localisent les zones d’altération hydrothermale prononcée. Les faciès sont divisés en grands groupes en fonction de leur nature et de leur degré d’altération. Ils montrent une grande variabilité des propriétés pétrophysiques. A l’état sain, les laves d’une part et les faciès pyroclastiques et de coulées de débris d’autre part, constituent deux groupes bien distincts. L’altération hydrothermale induit une restructuration totale du squelette matriciel et du réseau poreux. Elle permet une forte atténuation du signal magnétique et le développement d’un groupe ayant des propriétés réservoirs intermédiaires en diminuant les propriétés réservoirs des dépôts volcano-sédimentaires et en améliorant celles des laves. Le modèle de réservoir ainsi disponible conjugue des éléments structuraux et des hétérogénéités lithologiques permettant le transfert rapide des fluides, alors que les propriétés matricielles d’origines primaire et secondaire vont plutôt contrôler les propriétés de stockage de fluide et de chaleur. / The Vieux-Habitants area gathers indicators allowing to suppose a high-temperature hydrothermal system. The interpretation of geophysical data acquired for the exploration of this system requires the analysis of analogues. Several hydrothermal paleo-systems were studied in order to propose a conceptual model of a geothermal system for the Vieux-Habitants area. Studies of these analogues are based on a multi-scale study of the brittle deformation and a petrophysical characterization of the different volcanic rocks. The organization of fractures indicates the occurrence of a characteristic scale for each level of observation. Volcano-sedimentary units are far less deformed compared to highly fractured lavas. The brittle deformation in volcano-sedimentary deposits is highly localized in fractured corridors. Some fault intersections control major fluid flow at the kilometer scale. Moreover, the most hydrothermalized rocks are localized in the vicinity of these intersections. Volcanic rocks are divided according to their mechanism of formation (lava, debris flow…) and their degree of alteration. They exhibit strong heterogeneities of petrophysical properties. Fresh rocks are separated in two distinct groups, on one side lavas and on the other side debris flows and pyroclastic deposits. Hydrothermal alteration produces mineralogical replacements involving a complete reorganization of both the matrix skeleton and the pore network. It is marked by a removal of magnetic signal, an increase of porosity and permeability in lavas and a decrease of these properties in debris flows and pyroclastic deposits. Therefore, hydrothermalized rocks form a group with intermediate reservoir properties between the two groups of fresh rocks. The reservoir model combines both structural components and lithological heterogeneities that allow an efficient fluid transfer, whereas the matrix properties of primary and secondary origins will rather control the fluid and heat storage properties.

No description available.

Le cadre général de la thèse concerne la valorisation sous forme de production d'énergie électrique de la chaleur présente à quelques kilomètres de profondeur (3 à 5 km), en général dans des milieux peu perméables et fracturés. Notre objectif principal est d'étudier le phénomène des microséismes induits relativement au refroidissement, en nous basant sur une expérience de terrain de longue durée, menée sur le site de Rosemanowes (Cornwall, UK). Pour cela nous avons procédé à la mise en place d'un outil de calcul, FRACAS, capable de simuler ce phénomène en introduisant une approche à double milieu thermique pour mieux simuler le refroidissement du réservoir dû à l'injection de fluide à long terme, responsable des nouveaux mécanismes de ruptures dus à la traction de la roche. Dans ce contexte nous avons introduit un nouvel algorithme pour prendre en compte les manifestations d'instabilités, un mécanisme de « stick-slip » avec prise en compte d'une friction statique et d'une friction dynamique. La possibilité d'induire des microséismes est ensuite étudiée à partir des données issues d'un site particulier, avec deux modèles 3D proposant des approches géométriques différentes, un modèle déterministe et un modèle stochastique, dont les propriétés géométriques et physiques ont été tirées des observations et travaux antérieurs effectués sur ce site de Rosemanowes. La simulation thermo-hydro-mécanique (THM) du modèle déterministe nous a permis de modéliser les échanges thermiques en régime transitoire dans le réservoir formé par le système de forages RH12/RH15 et d'estimer un ordre de grandeur des tractions d'origine thermique. Pour mieux étudier l'effet induit par la contraction des blocs de roche dans le temps nous utilisons le modèle 3D stochastique dont l'objectif principal est de simuler de façon plus réaliste la progression dans l'espace les ruptures en cisaillement. Avec ce modèle nous avons constaté l'apparition différée d'une activité et l'effet d'un cycle de pulses de pression, ce qui suggère un moyen d'atténuer les fortes magnitudes potentielles des ruptures en cisaillement dues au refroidissement. / The general framework of our research deals with the development of geothermal energy for electricity production using the heat stored in geological formations at depths ranging in 3 to 5 km, Generally the environment is poorly permeable and fractured. Our main objective is to study the phenomenon of induced micro-earthquakes in relation to the cooling of the rock. The work is based on field experiences including long duration tests, conducted on the Rosemanowes site (Cornwall, UK). For this, we proceeded to the development of a calculation tool, FRACAS, able to simulate this phenomenon by introducing a dual thermal approach to better simulate the cooling of the reservoir due to long term fluid injections, which might be responsible for new failure mechanisms due to the induced tractions. In this context, we introduced a new algorithm to describe shear in stabilities, a mechanism of "stick-slip" type with the consideration of static/dynamic friction coefficients. The possibility of inducing micro-seismicity is then studied using the in situ data base, with two 3D models offering different geometric approaches, a deterministic model and a stochastic model whose geometrical and physical properties were obtained from observations and previous work on this Rosemanowes site. The Thermo-Hydro-Mechanical (THM) simulation using the deterministic model has allowed us to calibrate the transient heat transfer in the reservoir formed by the drilling system RH12/RH15 and to give an estimate of tensile stress of thermal origin. To better study the effect induced by the contraction of the rock during time, we use the stochastic 3D model whose main objective is to simulate a more realistic spatial migration of shear ruptures. With this model we found a delayed onset of shear activity and discuss the effect of pressure step tests. The results suggest a way to mitigate the potential impact of shear ruptures due to cooling.

La modélisation des massifs rocheux fracturés est un problèmes important dans de nombreux secteurs industriels, y compris, mais sans s'y limiter à l'exploitation pétrolière et gazière. Dans la littérature, les roches fracturées sont reconnues comme des milieux à double porosité et double perméabilité dans lesquels le réseau de fractures fournit la perméabilité primaire et la matrice rocheuse la perméabilité secondaire. L'idée de la dissociation de l'écoulement à l'intérieur du réseau de fractures et de la matrice,la double perméabilité, est toujours contestée pour les réservoirs fracturés. De nombreuses contributions sur cette question ont été présentées dans la littérature et les méthodes utilisées pourraient être classées dans deux approches principales : approches continues et discontinues. Chaque approche a ses avantages et ses limites. Pour surmonter les limites en gardant les avantages de ces deux approches, une approche nommée Embedded Fracture Continumm Approach (EFCA) qui emprunte le concept du modèle continu et intègre également l'effet des fractures explicites est considérée dans cette thèse. L'idée principale de cette approche repose sur le concept de la « cellule fracturée » représentant un milieu poreux qui a ses propres propriétés calculées à partir des propriétés de la matrice poreuse et des fractures qui la traversent. Le code de calcul développé dans le cadre de ce travail est basé sur la bibliothèque source DEAL.II. L'exactitude de l'EFCA a été étudiée à travers de différents tests. Plusieurs applications traitées dans ce travail comme la détermination des propriétés hydro-mécaniques effectives d'un site réel, estimation de la production de puits dans laquelle les fractures sont modélisées explicitement, démontrent la performance de l'EFCA dans la modélisation des roches fracturées ainsi que l'effet de la double porosité et de la double perméabilité aux comportements des réservoirs fracturés. / Fractured rock masses modeling is a challenge issue in many field of industry including but not limited to oiland gas exploitation. In the literature, fractured rock masse are in many cases recognized as double permeability medium in which fracture network provides the primary permeability and rock matrix plays asthe second one. The idea of dissociation of flow inside the fracture network and the matrix, the double permeability, is still challenged for fractured reservoirs. Numerous contributions on this issue have been presented in the past could be cast in two main approaches: continuum media approach and discontinuous approach. Each approach has its advantages and limitations. To overcome the limitation and to take advantage of these two approaches, the Embedded Fractured Continuum Approach (EFCA) which borrows the concept of continuum models and also incorporates the effect of explicit fractures is considered in this thesis. The principal idea of this approach lies on the concept of fracture cell representing a porous medium that has their own properties calculated from the properties of porous matrix and fractures intersecting it.The development in this work was conducted by using the library source code DEAL.II. The accuracy of EFCA was investigated through different verifications. Through some applications: determination of effective hydro-mechanical properties of an actual site, estimation of well production in which necessary fractures are modeled explicitly, we demonstrate the performance of the EFCA in the modeling fracture drock masses as well as the effect of double porosity and double permeability on behaviours of fractured reservoirs.

No description available.

A significant amount of Viscous Oil (e.g., heavy oil, extra heavy oil, and bitumen) is trapped in Naturally Fractured Carbonate Reservoirs also known as NFCRs. The word VO endowment in NFCRs is estimated at ~ 2 Trillion barrels mostly reported in Canada, the USA, Russia, and the Middle East. To date, contributions to the world daily oil production from this immense energy resource remains negligible mainly due to the lack of appropriate production technologies. Implementation of a VO production technology such as steam injection is expensive (high capital investment), time-consuming, and people-intensive. Hence, before selecting a production technology for detailed economic analysis, use of cursory or broad screening tools or guides is a convenient means of gaining a quick overview of the technical feasibility of the various possible production technologies applied to a particular reservoir. Technical screening tools are only available for the purpose of evaluation of the reservoir performance parameters in oil sands for various thermal VO exploitation technologies such as Steam Assisted Gravity Drainage (SAGD), Cyclic Steam Stimulation (CSS), Horizontal well Cyclic steam Stimulation (HCS), and so on. Nevertheless, such tools are not applicable for VO NFCRs assessment without considerable modifications due to the different nature of these two reservoir types (e.g., presence and effects of fracture network on reservoir behavior, wettability, lithology, fabric, pore structure, and so on) and also different mechanisms of energy and mass transport. Considering the lack of robust and rapid technical reservoir screening tools for the purpose of quick assessment and performance prediction for VO NFCRs under thermal stimulation (e.g., steamflooding), developing such fast and precise tools seems inevitable and desirable. In this dissertation, an attempt was made to develop new screening tools for the purpose of reservoir performance prediction in VO NFCRs using all the field and laboratory available data on a particular thermal technology (vertical well steamflooding). Considering the complex and heterogeneous nature of the NFCRs, there is great uncertainty associated with the geological nature of the NFCRs such as fracture and porosity distribution in the reservoir which will affect any modeling tasks aiming at modeling of processes involved in thermal VO production from these types of technically difficult and economically unattractive reservoirs. Therefore, several modeling and analyses technqiues were used in order to understand the main parameters controlling the steamflooding process in NFCRs and also cope with the uncertainties associated with the nature of geologic, reservoir and fluid properties data. Thermal geomechanics effects are well-known in VO production from oil sands using thermal technologies such as SAGD and cyclic steam processes. Hence, possible impacts of thermal processes on VO NFCRs performance was studied despite the lack of adequate field data. This dissertation makes the following contributions to the literature and the oil industry: Two new statistical correlations were developed, introduced, and examined which can be utilized for the purpose of estimation of Cumulative Steam to Oil Ratio (CSOR) and Recovery Factor (RF) as measures of process performance and technical viability during vertical well steamflooding in VO Naturally Fractured Carbonate Reservoirs (NFCRs). The proposed correlations include vital parameters such as in situ fluid and reservoir properties. The data used are taken from experimental studies and also field trials of vertical well steamflooding pilots in viscous oil NFCRs reported in the literature. The error percentage for the proposed correlations is < 10% for the worst case and contains fewer empirical constants compared with existing correlations for oil sands. The interactions between the parameters were also considered. The initial oil saturation and oil viscosity are the most important predictive factors. The proposed correlations successfully predicted steam/oil ratios and recovery factors in two heavy oil NFCRs. These correlations are reported for the first time in the literature for this type of VO reservoirs. A 3-D mathematical model was developed, presented, and examined in this research work, investigating various parameters and mechanisms affecting VO recovery from NFCRs using vertical well steamflooding. The governing equations are written for the matrix and fractured medium, separately. Uncertainties associated with the shape factor for the communication between the matrix and fracture is eliminated through setting a continuity boundary condition at the interface. Using this boundary condition, the solution method employed differs from the most of the modeling simulations reported in the literature. A Newton-Raphson approach was also used for solving mass and energy balance equations. RF and CSOR were obtained as a function of steam injection rate and temperature and characteristics of the fractured media such as matrix size and permeability. The numerical solution clearly shows that fractures play an important role in better conduction of heat into the matrix part. It was also concluded that the matrix block size and total permeability are the most important parameters affecting the dependent variables involved in steamflooding. A hybrid Artificial Neural Network model optimized by co-implementation of a Particle Swarm Optimization method (ANN-PSO) was developed, presented, and tested in this research work for the purpose of estimation of the CSOR and RF during vertical well steamflooding in VO NFCRs. The developed PSO-ANN model, conventional ANN models, and statistical correlations were examined using field data. Comparison of the predictions and field data implies superiority of the proposed PSO-ANN model with an absolute average error percentage < 6.5% , a determination coefficient (R2) > 0.98, and Mean Squared Error (MSE) < 0.06, a substantial improvement in comparison with conventional ANN model and empirical correlations for prediction of RF and CSOR. This indicates excellent potential for application of hybrid PSO-ANN models to screen VO NFCRs for steamflooding. This is the first time that the ANN technique has been applied for the purpose of performance prediction of steamflooding in VO NFCRs and also reported in the literature. The predictive PSO-ANN model and statistical correlations have strong potentials to be merged with heavy oil recovery modeling softwares available for thermal methods. This combination is expected to speed up their performance, reduce their uncertainty, and enhance their prediction and modeling capabilities. An integrated geological-geophysical-geomechanical approach was designed, presented, and applied in the case of a NFCR for the purpose of fracture and in situ stresses characterization in NFCRs. The proposed methodology can be applied for fracture and in situ stresses characterization which is beneficial to various aspects of asset development such as well placement, drilling, production, thermal reservoir modeling incorporating geomechanics effects, technology assessment and so on. A conceptual study was also conducted on geomechanics effects in VO NFCRs during steamflooding which is not yet well understood and still requires further field, laboratory, and theoretical studies. This can be considered as a small step forward in this area identifying positive potential of such knowledge to the design of large scale thermal operations in VO NFCRs.

A significant amount of Viscous Oil (e.g., heavy oil, extra heavy oil, and bitumen) is trapped in Naturally Fractured Carbonate Reservoirs also known as NFCRs. The word VO endowment in NFCRs is estimated at ~ 2 Trillion barrels mostly reported in Canada, the USA, Russia, and the Middle East. To date, contributions to the world daily oil production from this immense energy resource remains negligible mainly due to the lack of appropriate production technologies. Implementation of a VO production technology such as steam injection is expensive (high capital investment), time-consuming, and people-intensive. Hence, before selecting a production technology for detailed economic analysis, use of cursory or broad screening tools or guides is a convenient means of gaining a quick overview of the technical feasibility of the various possible production technologies applied to a particular reservoir. Technical screening tools are only available for the purpose of evaluation of the reservoir performance parameters in oil sands for various thermal VO exploitation technologies such as Steam Assisted Gravity Drainage (SAGD), Cyclic Steam Stimulation (CSS), Horizontal well Cyclic steam Stimulation (HCS), and so on. Nevertheless, such tools are not applicable for VO NFCRs assessment without considerable modifications due to the different nature of these two reservoir types (e.g., presence and effects of fracture network on reservoir behavior, wettability, lithology, fabric, pore structure, and so on) and also different mechanisms of energy and mass transport. Considering the lack of robust and rapid technical reservoir screening tools for the purpose of quick assessment and performance prediction for VO NFCRs under thermal stimulation (e.g., steamflooding), developing such fast and precise tools seems inevitable and desirable. In this dissertation, an attempt was made to develop new screening tools for the purpose of reservoir performance prediction in VO NFCRs using all the field and laboratory available data on a particular thermal technology (vertical well steamflooding). Considering the complex and heterogeneous nature of the NFCRs, there is great uncertainty associated with the geological nature of the NFCRs such as fracture and porosity distribution in the reservoir which will affect any modeling tasks aiming at modeling of processes involved in thermal VO production from these types of technically difficult and economically unattractive reservoirs. Therefore, several modeling and analyses technqiues were used in order to understand the main parameters controlling the steamflooding process in NFCRs and also cope with the uncertainties associated with the nature of geologic, reservoir and fluid properties data. Thermal geomechanics effects are well-known in VO production from oil sands using thermal technologies such as SAGD and cyclic steam processes. Hence, possible impacts of thermal processes on VO NFCRs performance was studied despite the lack of adequate field data. This dissertation makes the following contributions to the literature and the oil industry: Two new statistical correlations were developed, introduced, and examined which can be utilized for the purpose of estimation of Cumulative Steam to Oil Ratio (CSOR) and Recovery Factor (RF) as measures of process performance and technical viability during vertical well steamflooding in VO Naturally Fractured Carbonate Reservoirs (NFCRs). The proposed correlations include vital parameters such as in situ fluid and reservoir properties. The data used are taken from experimental studies and also field trials of vertical well steamflooding pilots in viscous oil NFCRs reported in the literature. The error percentage for the proposed correlations is < 10% for the worst case and contains fewer empirical constants compared with existing correlations for oil sands. The interactions between the parameters were also considered. The initial oil saturation and oil viscosity are the most important predictive factors. The proposed correlations successfully predicted steam/oil ratios and recovery factors in two heavy oil NFCRs. These correlations are reported for the first time in the literature for this type of VO reservoirs. A 3-D mathematical model was developed, presented, and examined in this research work, investigating various parameters and mechanisms affecting VO recovery from NFCRs using vertical well steamflooding. The governing equations are written for the matrix and fractured medium, separately. Uncertainties associated with the shape factor for the communication between the matrix and fracture is eliminated through setting a continuity boundary condition at the interface. Using this boundary condition, the solution method employed differs from the most of the modeling simulations reported in the literature. A Newton-Raphson approach was also used for solving mass and energy balance equations. RF and CSOR were obtained as a function of steam injection rate and temperature and characteristics of the fractured media such as matrix size and permeability. The numerical solution clearly shows that fractures play an important role in better conduction of heat into the matrix part. It was also concluded that the matrix block size and total permeability are the most important parameters affecting the dependent variables involved in steamflooding. A hybrid Artificial Neural Network model optimized by co-implementation of a Particle Swarm Optimization method (ANN-PSO) was developed, presented, and tested in this research work for the purpose of estimation of the CSOR and RF during vertical well steamflooding in VO NFCRs. The developed PSO-ANN model, conventional ANN models, and statistical correlations were examined using field data. Comparison of the predictions and field data implies superiority of the proposed PSO-ANN model with an absolute average error percentage < 6.5% , a determination coefficient (R2) > 0.98, and Mean Squared Error (MSE) < 0.06, a substantial improvement in comparison with conventional ANN model and empirical correlations for prediction of RF and CSOR. This indicates excellent potential for application of hybrid PSO-ANN models to screen VO NFCRs for steamflooding. This is the first time that the ANN technique has been applied for the purpose of performance prediction of steamflooding in VO NFCRs and also reported in the literature. The predictive PSO-ANN model and statistical correlations have strong potentials to be merged with heavy oil recovery modeling softwares available for thermal methods. This combination is expected to speed up their performance, reduce their uncertainty, and enhance their prediction and modeling capabilities. An integrated geological-geophysical-geomechanical approach was designed, presented, and applied in the case of a NFCR for the purpose of fracture and in situ stresses characterization in NFCRs. The proposed methodology can be applied for fracture and in situ stresses characterization which is beneficial to various aspects of asset development such as well placement, drilling, production, thermal reservoir modeling incorporating geomechanics effects, technology assessment and so on. A conceptual study was also conducted on geomechanics effects in VO NFCRs during steamflooding which is not yet well understood and still requires further field, laboratory, and theoretical studies. This can be considered as a small step forward in this area identifying positive potential of such knowledge to the design of large scale thermal operations in VO NFCRs.