Geothermal contribution to the energy mix of a heating network when using Aquifer Thermal Energy Storage: modeling and application to the Paris basin

International audienceAquifer Thermal Energy Storage (ATES) is a promising solution for reducing the time mismatch between energy production and demand in urban environments, and recent successful experiences suggest that technical issues can be overcome. The Paris area is a priori a favorable region, since there is locally a surplus of heat production during the summer, an appropriate geological reservoir and both existing and projected district heating networks. This article focuses on a remaining issue: estimating the geothermal contribution to the energy mix of a district heating network over time when using an ATES. This result would then enable estimating the fuel cost savings obtained by avoiding the consumption of expensive energies during the winter retrieval. This work considers an ATES made of two reversible wells reaching the Dogger aquifer and providing energy to a new low-temperature district heating network heating 7,500 housing-equivalents. Non-geothermal energy sources with fluctuating prices over time are used for winter peak demand and for summer heat storage. The temperature of brine unloading at the hot and cold wells is simulated and the adequacy of this geothermal system to meet the load is studied in order to evaluate the time dependent energy mix of the network. Results suggest that in average over the 30 years of operation, the ATES delivers 54 GWh per year to the heating system, i.e. a power of 9.5 MW during the 34 unloading winter weeks. The geothermal energy share in the energy mix is 70%, higher than the 50% possible with a conventional geothermal doublet. The ratio of energy delivered by the ATES divided by energy spent for storage reaches 143%, and is only slightly reduced to 137% when the cold storage is located on an existing cold plume created by past geothermal energy operations

Review and analysis of historical leakages from storage salt caverns wells

Twelve incidents involving well casing and/or cement leaks in the salt caverns storage industry are described. These incidents occurred at the following storage sites: Eminence salt dome, Mississippi; Elk City, Oklahoma; Conway, Kansas; Yoder, Kansas; Mont Belvieu, Texas; Teutschenthal/Bad Lauchstädt, Germany; Clute, Texas; Mineola, Texas; Hutchinson, Kansas; Magnolia, Louisiana; Boling, Texas; Epe, Germany. Mechanisms leading to a casing leak and consequences are discussed. In most cases, a breach in a steel casing occurred at a depth where a single casing was isolating the stored product from the geological formations. The origin of the breach was due in most cases to poor welding/screwing conditions and corrosion, or excessive deformation of the rock formation. In this, the age of the well is often influential. In many cases, the leak path does not open directly at ground level; fugitive hydrocarbons first escape and accumulate in the subsurface prior to migrating through shallower horizons and escaping at ground surface. A pressure differential between hydrocarbons in the borehole and fluids in the rock mass favours fast leak rates. A wellhead pressure drop often is observed, even when the stored product is natural gas. The incidents described suggest that thorough monitoring (tightness tests) and a correct well design would lessen considerably the probability of a casing leak occurring

Review and analysis of historical leakages from storage salt caverns wells

Twelve incidents involving well casing and/or cement leaks in the salt caverns storage industry are described. These incidents occurred at the following storage sites: Eminence salt dome, Mississippi; Elk City, Oklahoma; Conway, Kansas; Yoder, Kansas; Mont Belvieu, Texas; Teutschenthal/Bad Lauchstädt, Germany; Clute, Texas; Mineola, Texas; Hutchinson, Kansas; Magnolia, Louisiana; Boling, Texas; Epe, Germany. Mechanisms leading to a casing leak and consequences are discussed. In most cases, a breach in a steel casing occurred at a depth where a single casing was isolating the stored product from the geological formations. The origin of the breach was due in most cases to poor welding/screwing conditions and corrosion, or excessive deformation of the rock formation. In this, the age of the well is often influential. In many cases, the leak path does not open directly at ground level; fugitive hydrocarbons first escape and accumulate in the subsurface prior to migrating through shallower horizons and escaping at ground surface. A pressure differential between hydrocarbons in the borehole and fluids in the rock mass favours fast leak rates. A wellhead pressure drop often is observed, even when the stored product is natural gas. The incidents described suggest that thorough monitoring (tightness tests) and a correct well design would lessen considerably the probability of a casing leak occurring

Le développement de la prise en compte de l'étanchéité dans l'industrie des cavités salines, des techniques permettant de la tester et du concept de "Mechanical Integrity Test"

Salt caverns started being produced as a by-product of the salt production industry. In the 1940s, these caverns started being used for storage of hydrocarbons. There are now 2000 salt caverns globally storing liquid, gaseous or supercritical fluids. The necessity to test the tightness of the storage caverns came along with their development. A large variety of techniques have been proposed, varying over time, companies and countries. In addition, several acceptance criteria of these tests have been, and are still, used. While first attempts were to relate a fail/pass criteria to possible impacts, the industry rather relied on criteria that have shown their applicability and their effectiveness through a track record of a limited number of accidents when applied. This work presents all these initiatives and their historical context. Measurements uncertainties are propagated in order to enable to compare the accuracies of the main tightness test techniques. Invented in the 1970s, the nitrogen/brine "Mechanical Integrity Test" progressively became the reference tightness test technique for salt caverns. The comparison of tests accuracies shows it is excellent. Among massive storage options, salt caverns now have a singular property: their tightness can be tested very accurately.Les cavités salines ont été initialement un sous-produit de l'extraction industrielle de sel. Dans les années 40, elles ont commencé à être utilisées pour y stocker des hydrocarbures. Il y a aujourd'hui 2000 cavités salines dans le monde stockant des fluides liquides, gazeux ou supercritiques. La nécessité de tester l'étanchéité des cavités de stockage est venue avec leur développement. Une grande diversité de techniques a été proposée, variant dans le temps, selon les sociétés et les pays. Par ailleurs, plusieurs critères d'acceptation de ces tests ont été, et sont encore, utilisés. Si les premiers critères ont tenté de relier le succès ou l'échec d'un test à de possibles impacts, l'industrie a préféré utiliser des critères qui ont démontré leur applicabilité et leur efficacité via un historique limité d'accidents lorsqu'ils étaient appliqués. Ce travail présente toutes ces initiatives et leur contexte historique. Les incertitudes de mesure sont propagées afin de permettre de comparer la précision des principaux tests. Inventé dans les années 70, le "Mechanical Integrity Test" azote/saumure est progressivement devenu la référence des tests d'étanchéité de cavités salines. La comparaison des précisions montre qu'il est excellent. Parmi les options de stockage massif, les cavités salines ont aujourd'hui une propriété singulière: leur étanchéité peut être testée très précisément

Le développement de la prise en compte de l'étanchéité dans l'industrie des cavités salines, des techniques permettant de la tester et du concept de "Mechanical Integrity Test"

Salt caverns started being produced as a by-product of the salt production industry. In the 1940s, these caverns started being used for storage of hydrocarbons. There are now 2000 salt caverns globally storing liquid, gaseous or supercritical fluids. The necessity to test the tightness of the storage caverns came along with their development. A large variety of techniques have been proposed, varying over time, companies and countries. In addition, several acceptance criteria of these tests have been, and are still, used. While first attempts were to relate a fail/pass criteria to possible impacts, the industry rather relied on criteria that have shown their applicability and their effectiveness through a track record of a limited number of accidents when applied. This work presents all these initiatives and their historical context. Measurements uncertainties are propagated in order to enable to compare the accuracies of the main tightness test techniques. Invented in the 1970s, the nitrogen/brine "Mechanical Integrity Test" progressively became the reference tightness test technique for salt caverns. The comparison of tests accuracies shows it is excellent. Among massive storage options, salt caverns now have a singular property: their tightness can be tested very accurately.Les cavités salines ont été initialement un sous-produit de l'extraction industrielle de sel. Dans les années 40, elles ont commencé à être utilisées pour y stocker des hydrocarbures. Il y a aujourd'hui 2000 cavités salines dans le monde stockant des fluides liquides, gazeux ou supercritiques. La nécessité de tester l'étanchéité des cavités de stockage est venue avec leur développement. Une grande diversité de techniques a été proposée, variant dans le temps, selon les sociétés et les pays. Par ailleurs, plusieurs critères d'acceptation de ces tests ont été, et sont encore, utilisés. Si les premiers critères ont tenté de relier le succès ou l'échec d'un test à de possibles impacts, l'industrie a préféré utiliser des critères qui ont démontré leur applicabilité et leur efficacité via un historique limité d'accidents lorsqu'ils étaient appliqués. Ce travail présente toutes ces initiatives et leur contexte historique. Les incertitudes de mesure sont propagées afin de permettre de comparer la précision des principaux tests. Inventé dans les années 70, le "Mechanical Integrity Test" azote/saumure est progressivement devenu la référence des tests d'étanchéité de cavités salines. La comparaison des précisions montre qu'il est excellent. Parmi les options de stockage massif, les cavités salines ont aujourd'hui une propriété singulière: leur étanchéité peut être testée très précisément

Le développement de la prise en compte de l'étanchéité dans l'industrie des cavités salines, des techniques permettant de la tester et du concept de "Mechanical Integrity Test"

Les cavités salines ont été initialement un sous-produit de l'extraction industrielle de sel. Dans les années 40, elles ont commencé à être utilisées pour y stocker des hydrocarbures. Il y a aujourd'hui 2000 cavités salines dans le monde stockant des fluides liquides, gazeux ou supercritiques. La nécessité de tester l'étanchéité des cavités de stockage est venue avec leur développement. Une grande diversité de techniques a été proposée, variant dans le temps, selon les sociétés et les pays. Par ailleurs, plusieurs critères d'acceptation de ces tests ont été, et sont encore, utilisés. Si les premiers critères ont tenté de relier le succès ou l'échec d'un test à de possibles impacts, l'industrie a préféré utiliser des critères qui ont démontré leur applicabilité et leur efficacité via un historique limité d'accidents lorsqu'ils étaient appliqués. Ce travail présente toutes ces initiatives et leur contexte historique. Les incertitudes de mesure sont propagées afin de permettre de comparer la précision des principaux tests. Inventé dans les années 70, le "Mechanical Integrity Test" azote/saumure est progressivement devenu la référence des tests d'étanchéité de cavités salines. La comparaison des précisions montre qu'il est excellent. Parmi les options de stockage massif, les cavités salines ont aujourd'hui une propriété singulière: leur étanchéité peut être testée très précisément.Salt caverns started being produced as a by-product of the salt production industry. In the 1940s, these caverns started being used for storage of hydrocarbons. There are now 2000 salt caverns globally storing liquid, gaseous or supercritical fluids. The necessity to test the tightness of the storage caverns came along with their development. A large variety of techniques have been proposed, varying over time, companies and countries. In addition, several acceptance criteria of these tests have been, and are still, used. While first attempts were to relate a fail/pass criteria to possible impacts, the industry rather relied on criteria that have shown their applicability and their effectiveness through a track record of a limited number of accidents when applied. This work presents all these initiatives and their historical context. Measurements uncertainties are propagated in order to enable to compare the accuracies of the main tightness test techniques. Invented in the 1970s, the nitrogen/brine "Mechanical Integrity Test" progressively became the reference tightness test technique for salt caverns. The comparison of tests accuracies shows it is excellent. Among massive storage options, salt caverns now have a singular property: their tightness can be tested very accurately

Maximum admissible pressure in salt caverns used for brine production and hydrocarbon storage

International audienceTightness is a fundamental prerequisite to any underground storage. In storage salt caverns, a safe maximum admissible pressure must be selected to avoid product loss. The tensile strength of salt is small, and cavern pressure must be kept lower than geostatic pressure or, more precisely, lower than the least compressive stress at the cavern wall. The vertical stress can be assessed through density logs. The redistribution of stresses in the rock mass, due to the visco-plastic nature of rock salt, must be taken into account. A couple of cases in which a hydraulic connection between one cavern and another cavern, or between a cavern and the edge of a salt dome, are known. These connections originated in geological anomalies rather than in the creation of a fracture. There exists a pressure threshold, lower than the geostatic pressure, for which micro-fracturing and an increase in salt permeability occur, vindicating the position that a safety margin is needed when selecting the maximum pressure. Well tightness is important as well; it depends on several factors, among which are the quality of the cement, and the maximum fluid pressure in the cavern and along the access well. A tightness test is mandatory. The Nitrogen Leak Test is the most common such test. A review of selected gas-storage sites shows that, in most cases, the maximum admissible gradient at the casing shoe is 0.018 MPa/m (0.8 psi/ft), and up to 0.019 MPa/m (0.85 psi/ft) in some American states, values that are consistent with the considerations listed above

Etude probabiliste des vagues cycloniques le long du littoral Guadeloupéen

National audienceLa submersion marine liée aux cyclones fait partie des risques majeurs rencontrés dans les Antilles françaises. Une bonne estimation des états de mer extrêmes est un élément primordial pour l'aménagement du littoral et une gestion raisonnée des risques. Dans cette étude, une estimation des périodes de retour des hauteurs de vagues cycloniques en zone côtière a été réalisée sur plusieurs sites du littoral Guadeloupéen. La méthode utilisée comprend (1) la sélection d'évènements pertinents dans la base de données HURDAT (2) la reconstitution des champs de vent pour chaque cyclone à l'aide d'un modèle paramétrique (3) la modélisation des vagues jusqu'en zone côtière (4) une analyse statistique sur la hauteur significative des vagues. Le système de modélisation a été validé par comparaison avec des données de bouées sur quelques cyclones récents. Les premiers résultats obtenus ont montré une plus forte exposition des sites de la façade Atlantique par rapport à ceux côté mer des Caraïbes. Cependant, les intervalles de confiance calculés restent importants car la base de données historiques utilisée ne fournit qu'un nombre restreint d'évènements utilisables dans l'analyse statistique. Des pistes d'amélioration sont proposées pour des études ultérieures

Mitigation and remediation technologies and practices in case of undesired migration of CO2 from a geological storage unit—Current status

International audienceOne of the main objectives of operators and regulators involved in CO2 geological storage activities is to ensure that the injected CO2 will remain safely in the underground for a long period of time. Therefore, in addition to the screening and evaluation of the performance of a potential CO2 storage site, risks of unwanted migration in the subsurface should be addressed and adequately managed. This can include the use of methods to mitigate those risks and ultimately to remediate potential adverse effects. This paper reviews the status of knowledge with regards to the mitigation and remediation technologies, from mature techniques adapted from other fields, such as oil and gas industry and environmental clean-up, to research topics offering potential new possibilities. Several categories can be defined: (1) interventions on operational or decommissioned wells to re-establish their integrity; (2) pressure/fluid management techniques for countering the leakage driving forces and/or removing the leaking fluids; (3) emerging technologies providing new mitigation opportunities for controlling undesired CO2 migration; (4) techniques to remediate the impacts potentially induced by such a migration. This technical state of the art is completed by the actual practices in the emerging field of CO2 geological storage established from the regulatory requirements and guidelines, and from the experience gained in existing storage projects over the world. This article concludes on important best practices stemming from this review and on future challenges in terms of research topics and operational needs