Pilot Abandonment Testof a Very Deep Gas Storage Salt Cavern

• Published in: Oil & gas science and technology 2007-05, Vol.62 (3), p.287-296
• Main Authors: Durup, J. G., Vidal, F., Rolin, C.
• Format: Article
• Language: English
• Subjects: Physics
• ISSN: 1294-4475; 1953-8189
• DOI: 10.2516/ogst:2007024

As a result of knowledge gained initially from a series of succinct sealed well and cavern field tests performed in the late 1980s and early 1990s by Gaz de France (EZ58; EZ53), issues related to the long term abandonment of salt caverns became more focused. The tests were performed in cooperation with École Polytechnique (France) and were partially funded by the Solution Mining Research Institute (USA). The long-term abandonment (sealing or plugging) of a solution-mined cavern in a salt formation that has been used for mineral production, hydrocarbon storage, or waste disposal has been a contemporary topic for many years. Sealing and abandonment of caverns in salt formations differs from sealing of an oil and gas well principally for two reasons: - cavern wells are generally completed with much larger casings than oil and gas exploration and production wells; - the cavern fluid pressure rises after sealing. The first difference is not a significant deterrent to effective cavern sealing and abandonment. Essentially all of the uncertainties and complexities associated with cavern sealing and abandonment are a direct result of the second difference – the fact that the cavern fluid pressure rises through time. After a short introduction to solution mining of salt caverns and their use as underground gas storages, the paper will first discuss the factors affecting cavern fluid pressure increase after sealing. The second part of the paper will highlight the practical impacts of these factors on a deep salt cavern abandonment experiment (Cavern TE02; 1500 meters deep), currently being performed on the natural gas storage of Tersanne operated for over 35 years by Gaz de France. En raison de connaissances acquises initialement à partir d'une série d'essais in situ sur des puits et des cavités salines, réalisés vers la fin des années 80 et début 90 par Gaz de France, les enjeux relatifs à l'abandon à long terme des cavités salines ont commencé à être mieux compris. Ces expérimentations ont été réalisées en étroite collaboration avec l'École Polytechnique (France) et le Solution Mining Research Institute (USA). L'abandon à long terme (la fermeture définitive) des cavités qui ont été creusées par dissolution dans une formation salifère, soit pour extraire du sel minéral, soit pour le stockage d'hydrocarbures ou des déchets, a été une préoccupation depuis de nombreuses années. En fait, la fermeture définitive et l'abandon des cavités salines sont plus délicats que l'a