Institut Francais Du Pe'trole

Other

Compagnie Generale De Geophysique

Gaz De France-service National

Axelle Baroni

Patrick Meynier

Georges Constantinou

Claude Beauducel

Seismic emission system for use in an underground formation, using at least one seismic source movable successively in a plurality of prepared activation locations and method for implementing same. The system comprises for example a plurality of coupling devices () including each for example two anchor elements (') tightly coupled with the formation (by cementing for example). These anchor elements are secured to the seismic source (V) such as a vibrator of any type or an impulsive source by transmission elements (). The seismic source is coupled with coupling device () by fast locking means (). Coupling devices () can be preinstalled at a plurality of prepared activation locations above the formation to be monitored. Seismic monitoring operations can be carried out by moving at least one seismic source successively between the different locations where coupling devices () are installed.

Mobile system for seismic emission with fixed coupling devices, and method therefor

An electromechanical device for generating elastic waves in a material medium such as the subsoil in a frequency range where the wavelengths of the waves generated are great in view of the dimensions of the device, and method of implementation. The device comprises one or more vibrators which are buried in the medium, associated with a control system. Each vibrator comprises at least one inertia mass (), several plates () providing mechanical coupling with the medium, electromechanical transducers () connecting inertia masses () to plates (). A control system () applies to the various transducers () respective control signals so that the resulting elastic wavefield generated in the medium by the device is preferentially oriented in one or more directions.

Device for generating focused elastic waves in a material medium such as underground, and method using same

A hydrophone which is automatically inhibited when the immersion depth exceeds a predetermined threshold by action, on the push element ( ) of a switch ( ), of a flexible wall that bends under the action of the outside pressure. The hydrophone comprises a tubular body ( ) with two chambers ( ) separated by a partition ( ). One of the chambers is closed by a flexible diaphragm ( ). Switch ( ) is fixed at the center of one of the chambers. Diaphragm ( ) can push down on and actuate push element ( ) by bending. The body can advantageously consist of two parts that can be screwed onto one another, which allows easier adjustment of the inhibition pressure. A pressure-sensitive reception unit (S) is arranged in the other chamber.

Hydrophone with automatic inhibition in case an adjustable immersion threshold is exceeded

Very low distortion hydrophone comprising at least one pair of sensitive elements ( and ) of piezoelectric type (for example and not limitatively), associated with at least one of the opposite flexible faces of a housing ( ) formed by assembling cups ( and ) with rigid edges. The opposite faces of one of the discs, ( ), are provided with electrodes over the total surface thereof. On the other hand, at least one of electrodes ( and ) associated with the opposite faces of second disc ( ) only covers one or more portions (an annular strip for example) of each of these faces in an external zone of each cup ( ) more subjected to nonlinear stresses. Electrodes ( and ) of the two sensitive discs ( and ) are interconnected so as to make the difference between the electric signals generated by the two discs in response to the pressures applied, with the effect, experimentally verified, that the distortion resulting from this layout, notably due to a second harmonic ( ), is practically suppressed. The hydrophone can be used for geophysics, detection or locating, etc.

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Rueil Malmaison, France

Axelle Baroni