Mechanical stability of a salt cavern submitted to high-frequency cycles

International audienceStorage of natural gas in salt caverns had been developed mainly for seasonal storage, resulting in a small number of yearly pressure cycles and moderate gas-production rates. The needs of energy traders are changing toward more aggressive operational modes. Gas temperature changes and additional stresses generated by high-frequency cycling in a storage cavern are discussed. It is proved that when fast pressure changes or short-period gas pressure cycles are considered, the thickness of the thermally disturbed zone at the cavern wall is relatively small. Refined meshes of the disturbed zone are required when performing numerical computations

Sounds good? Determination of a gas/brine interface by an acoustic method at Manosque

International audienceWater hammers commonly are observed at wellheads and often are considered a potential hazard that should be avoided. Nevertheless, there are a few situations in which water hammers provide very valuable information about a well. A comprehensive data-acquisition and analysis system has been developed by Brouard Consulting and Ecole Polytechnique. One potential application of that system is determining the depth of an interface between two fluids. This application has been tested successfully at the Manosque field. It is demonstrated here how this low-cost and non-intrusive system can be accurate and allows practical, real-time measurements

Mechanical stability of a salt cavern used for hydrogen storage

International audienceUnderground salt cavern storage is recognised as one of the most suitable technologiesto meet the challenges of the new European energy system. With the advantage of being mostlyimpermeable to gases, salt caverns are currently the only structures used to store hydrogen on amassive scale underground. This paper studies the consequences of a rapid withdrawal of hydrogenon the mechanical stability of a salt cavern. Gaseous hydrogen cooling could generate rock saltdilation, cavern closure and tensile stresses at the cavern wall. Numerical computations using thefinite element method help to evaluate the geomechanical consequences of a rapid depressurisationin a selected cavern for an underground hydrogen storage demonstrator in France

Modélisation de l'éruption d'une cavité saline de stockage souterrain d'hydrogène

International audienceModélisation de l'éruption d'une cavité saline de stockage souterrain d'hydrogèn

Modélisation de l'éruption d'une cavité saline de stockage souterrain d'hydrogène

International audienceModélisation de l'éruption d'une cavité saline de stockage souterrain d'hydrogèn

Effects of a rapid depressurization in a salt cavern

International audienceRapid gas depressurization leads to gas cooling followed by slow gas warming when the cavern is kept idle. Gas temperature drop depends upon withdrawal rate and cavern size. Thermal tensile stresses, resulting from gas cooling, may generate frac-tures at the wall and roof of a salt cavern. These fractures are perpendicular to the cavern wall; in most cases their depth of penetration is small. The distance between two parallel fractures becomes larger when fractures penetrate deeper in the rock mass, as some fractures stop growing. These conclusions can be supported by numerical computations based on fracture mechanics. Salt slabs are created. These slabs remain strongly bounded to the rock mass and it is believed that in many cases their weight is not large enough to allow them to break off the cavern wall. However, depth of penetration of the fractures must be computed to prove that they cannot be a concern from the point of view of cavern tightness

L'effondrement de 1873 à la mine de Varangéville

National audienceOn décrit l’effondrement d’un quartier de mine de sel dans lequel les piliers ont poinçonné le mur imbibé de saumure quand l’extension de la mine a diminué la raideur du toit. Le calcul numérique montre qu’au moment de l’effondrement une zone dilatante traversant toute la couche de sel s’était formée

Blowout Prediction on a Salt Cavern Selected for a Hydrogen Storage Pilot

International audienceTo prevent climate change, Europe and the world must shift to low-carbon and renewable energies. Hydrogen, as an energy vector, provides viable solutions for replacing polluting and carbon-emitting fossil fuels. Gaseous hydrogen can be stored underground and coupled with existing natural gas pipe networks. Salt cavern storage is the best suited technology to meet the challenges of new energy systems. Hydrogen storage caverns are currently operated in the UK and Texas. A preliminary risk analysis dedicated to underground hydrogen salt caverns highlighted the importance of containment losses (leaks) and the formation of gas clouds following blowouts, whose ignition may generate dangerous phenomena such as jet fires, unconfined vapor cloud explosions (UVCEs), or flashfires. A blowout is not a frequent accident in gas storage caverns. A safety valve is often set at a 30 m depth below ground level; it is automatically triggered following a pressure drop at the wellhead. Nevertheless, a blowout remains to be one of the significant accidental scenarios likely to occur during hydrogen underground storage in salt caverns. In this paper, we present modelling the subterraneous and aerial parts of a blowout on an EZ53 salt cavern fully filled with hydrogen