Gaz De France-(Gdf) Service National

Yvon Charnavel

Jean-Gerard Durup

Guy Boris

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 between a first sub-cavity and a last sub-cavity, the preliminary sub-cavities and the channels defining the preliminary communication space.

Process for hollowing out a cavity formed of a plurality of sub-cavities

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.

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Rosny Sous Bois, France

Yvon Charnavel