The experience of storing LNG and other cryogenic hydrocarbons in unlined excavated rock caverns has shown great difference in the predicted and the observed heat flow from the surrounding ground. The results indicate that some of the assumptions made in the analysis were wrong. It is believed that the development of cracks in the rock mass around the cavern is the main cause of the difference. In open cracks, movements of LNG may create convection, which has to be added to the heat transfer conduction in the impervious rock mass. Other causes of the difference could be scale-effects and invalid assumptions of the thermal rock properties to be independent of the temperature. This paper reports on the predicted thermal gradients around' a cavern and on the observed results from tests in a pilot-scale cavern. Finally, the paper outlines the reasons for divergence between predictions and performance.


L'experience de l'emmagasinage de LNG et autres hydrocarbonnes cryogeniques dans des cavernes non habillees a montre de grandes differences entre les flux thermiques predits et ceux observes dans les masses rocheuses qui les entrourent. Les resultats mont rent que certaines suppositions faites dans les analyses sont fausses. II est suppose que la presence de fissures dans la masse rocheuse avoisinante autour de la caverne en est la raison. Dans les fissures ouvertes, la circulation du LNG peut creer un phenomène de convergeance qui s'ajoute à la conductivite thermique de la masse rocheuse impermeable. D' autres raisons pourraient être un effet d'echelle et la fausse hypothèse que les paramètres thermiques seraient independants de la temperature. Cet article traîte Ie gradient de temperature suppose autour d'une caverne et compare au resultats d'essais effectues dans une caverne. Finalement les raisoins des differences sont analysees.


Die Erfahrung aus der Speicherung von LNG und anderen cryogen en Kohlenwasserstoffen in unausgekleideten Felskavernen hat große Unterschiede im vorhergesagten und beobachteten Warmefluß vom umgebenen Gebirge gezeigt Die Ergebnisse weisen aus, daß einige der fur die Untersuchungen gemachten Annahmen falsch waren. Es ist anzunehmen, daß die Entwicklung von Klueften im umgebenen Fels die Ursache fuer diese Unterschiede ist. In offenen Klueften erzeugt LNG Konvektion, zusatzlich zu Warmeleitung im dichten umgebenen Fels. Andere Ursachen können Maßstabseinfluesse sein, sowie unzutreffende Annahmen zu den thermischen Eigenschaften des Gesteins. Dieser Beitrag berichtet ueber die vorausgesagten Warmegradienten im Umfeld einer Kaverne und die beobachteten Resultate von Versuchen in einer Pilotkaverne. Schließlich werden die Gruende fuer die Abweichung der Vorhersage von den tatsachliche Ergebnissen dragelegt.


With the objective to gain a better understanding of the conditions when storing cold, gas liquids in unlined rock caverns, a group of companies have joined together to perform field tests. Chalmers University of Technology was given the responsibility to perform the tests which were carried out in a pilot-scale rock cavern located in Gothenburg, Sweden. The cavern was constructed in 1990. During 1991, the temperature in a first phase was lowered down to −40°C. In the next phase, started in 1995, the temperature was planned to be drawn down to −162°C by means of liquid nitrogen. But due to financial problems, the test was limited to a new test cycle down to −40°C. The facility is equipped with very comprehensive instrumentation, including about 205 temperature gauges and 140 deformation gauges. A micro-seismic network is also installed to control the reaction of the rock mass due to the low temperatures. Evaluation of all recorded data is underway; at the moment only temperature data can be presented. The aim of this paper is thus delimit to the predicted and observed temperature field around the cavern. The mechanical part will be considered in later publications.

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