Abstract: A process for hollowing out a cavity, by dissolution, in a ground formation comprising at least one layer containing predominantly salt, the process including the steps of drilling at least one hole having a substantially horizontal section arranged at least in part in the salt layer, providing in the drilled hole(s) an injection pipe, an extraction pipe and a preliminary communication space connecting the injection pipe and the extraction pipe, injecting a solvent of the salt, into the communication space, through one end of the injection pipe forming an injection point, extracting, through the extraction pipe, the brine formed by the dissolution of the salt, in contact with the solvent, producing a plurality of preliminary sub-cavities in the salt layer, and producing a succession of channels, isolated from the layer, the succession of channels connecting the plurality of preliminary sub-cavities in a fluid manner two at a time in order to form an open circuit for circulation of the solvent, expending betwe

Abstract: The invention concerns a process for excavating by dissolution an underground cavity in a thin salt layer, in order to store a fluid therein. According to the invention, the process includes the steps of producing an injection duct, an extraction duct, and a void for a communication space which places in communication the injection and extraction ducts, producing at least one blind tunnel void communicating with the communication space so as to enable the solvent to circulate and the salt to dissolve in the blind tunnel, injecting via the injection duct a solvent into the communication space, and extracting via the extraction duct the brine formed by the dissolution of the salt on contact with the solvent. The advantage of this process is that the excavated layer has a mechanically stable shape and a larger volume and is produced more cheaply than with prior processes.

Abstract: The method comprising measuring the rate at which working fluid is expelled from a cavity through a central tubing to a well head under atmospheric pressure at the well head; determining the shape of a zone of the well selected for positioning an interface between a test fluid and the working fluid; performing temperature measurements and pressure measurements over the full height of a cavity under atmospheric pressure at the well head; injecting additional working fluid into the central tubing or into the annular space until a predetermined test pressure is reached; measuring the compressibility of a cavity during the preceding step; injecting test fluid into the annular; measuring the depth of the interface between the test fluid and the working fluid for a first time at the end of injecting test fluid; measuring the test fluid and the working fluid pressures at the well head; measuring the level of the interface between the test fluid and the working fluid for a second time; and evaluating the real leakage