The exploration of large storage cavities has always a long-term consequence, which is the subsidence. This is due to the cavity convergence resulting from the loss of initial pressure equilibrium. After reviewing the subsidence phenomenology, by identifying what can be observed at the surface, and its environmental and structural consequences, some empirical and analytical means of estimating its deformation values are referred. With more detail, a numerical application is presented which uses coupled boundary and finite elements for subsidence evaluation due to deep storage cavities. This last characteristic gives rise to large extensions of deformed zones towards the surface. A real case of a storage cavity field with subsidence measurements made for more than ten years is taken as example and some predictions are made on future subsidence and horizontal displacement values.


L'exploration des cavites de stockage a toujours comme consequence à longue terme le phenomene de la subsidence. Celle-ci est le resultat de la convergence de la cavite en raison de la perte de l'equilibre initial des pressions. Apres une courte revision de la phenomenologie de la subsidence, par l'Identification de ce qu'on peut observer à la surface, et ses consequences environnernentales et structurales, on fait, reference à quelques moyens empiriques et analytiques pour evaluer les valeurs de deformation. Une application numerique pour le calcul de la subsidence, utilisant la methode couplee elements finis - equations integrales, est presentee avec plus de detail. Avec des cavites tres profondes l'extension des zones deformees à la surface devienne tres large. Un cas reel d'un champ de cavites de stockage, avec des mesures de subsidence faites depuis plus de dix ans, est pris comme exemple et on fait quelques previsions des valeurs futures de subsidence.


Die Ausnutzung von großen Speicherhöhlungen hat als langfristige Konsequenz, die Subsidence. Diese Senkungen entsprechen der Raumkonvergenz und resultiert aus dem Verlust des originelles mechanischen Gleichgewichts. Einigen empirischen und analytischen Methoden fuer die Schatzung dieser Subsidence sind gegeben nach einer Wiederholung der Subsidencephanomen wo Oberflachenbeobachtungen, umwelt und strukturelle Konsequenzen betrachtet wurden. Auf eine detaillierte Weise, ein numerisches Model ist presentiert indem gekoppelte Rand- und Finiten-elemente benutzt werden fuer die Ermittlung von Subsidence auf tiefen Speicherhöhlungen. Diese letzte Eigenschaft verursacht große verformten Zonen in Richtung zur Oberflache, Ein konkreten Beispiel von einern Speicherhöhlungenfeld mit Senkungsmessungen seit mehr als 10 Jahre wurde genommen und einige Vorhersagen auf zukuenftiger Senkungungen und horizontalen Verschiebungen wurden gemacht.


Storage cavities in salt formations are often designed and used for liquid or gaseous hydrocarbons strategic reserves. The dissolution process of void creation disturbs the initial equilibrium of the rock salt leading to cavity convergence, as internal pressure will always be less than geostatic pressure. This will cause a volume loss, with the inevitable economic consequences, and also give rise to surface deformations made up of subsidence and horizontal displacements.

The use of analytical models for these storage cavities is an essential tool to interpret the thermomechanical behavior observed in situ through local tests and measurements. They provide the means of estimating future evolution of the underground structures as well as its repercussions on the surface like for instance subsidence.

The numerical analysis of a storage cavity group is a three-dimensional problem leading to calculations difficult to perform. The solution can be approximated by a superposition of single cavity in infinite medium calculations if certain restrictions regarding field geometry are satisfied. The need of an accurate calculation of the subsidence due to one cavity is therefore needed. This is not easy with classical numerical methods, given the small dimensions of the cavity compared to its depth.

This content is only available via PDF.
You can access this article if you purchase or spend a download.