Institut Francais Du Pe'trole

Jean-Claude Dubois

Alain Delaunay

Patrick Meynier

Pierre-Claude Layotte

Marc Becquey

Andre James

Patrice Ricarte

Rodolphe Massu

A method is disclosed for determining, without carrying out a well-velocity survey or making a priori assumption on the velocity of the first medium, the primary static corrections to be applied to sets of seismic traces after seismic prospecting operations in an underground zone. A velocity model allows calculation of the corrections is essentially obtained by performing, for each position of the common midpoint, a continuous and progressive inversion of the first arrival times (time-distance curves), from short offsets to longer offsets, so as to allow going from a sequence of pairs connecting the offsets to the arrival times picked to a sequence of vertical data connecting the depth to the velocity or propagation of the waves.

Method for determining primary static corrections to be applied to seismic traces

A method and device for emitting radial seismic waves in a material medium by electromagnetic induction, used notably for generating seismic waves in cased or uncased wells or in a water mass is disclosed. Emission of radial waves is essentially obtained by radially expanding a metal tube ( ) under the effect of a magnetic pressure generated by electromagnetic induction with elastic waves being created in the medium under the effect of this expansion. The magnetic pressure is obtained by connecting a coil ( ) in line with the tube to a current generator ( ). The winding pitch of coil ( ) can be constant or variable. Tube ( ) can for example be added into a well or hole or it can be a tube portion of a cased well.

Method and device for emitting radial seismic waves in a material medium by electromagnetic induction

Vibrator comprising a single vibration generator coupled with the medium by a coupling element and means for controlling the generator, suited to apply thereto, on each emission, a single pilot signal obtained by combination of at least two signals of different frequencies (f , f ), fixed or preferably variable within at least partly separate frequency bands, and non-linear elastic transmission means suited to generate in the medium vibrations at a frequency depending on the frequency difference of the two vibrational signals. The exploration method comprises using the vibrator in order to emit very low-frequency vibrations in the medium reception by pickups (R) of the waves reflected by the medium in response to the vibrations emitted and recording thereof, and selection by correlation of the vibrational signals with a synthetic signal whose frequency is connected with the frequency difference of the signals forming the pilot signal.

Vibrator and method of exploring a material medium by means of very low-frequency elastic vibrations

Multiple shocks of a vertically falling mass against a target member coupled with the earth are prevented by holding the mass and retaining it above the target member after its first bounce. This retention is accomplished by means of deformable elements laterally pressed against the mass body by jack rods actuated in response to a control signal produced by a sensor at the moment of the first impact of the mass.

Device for avoiding multiple bounces against a target of a mass _falling

The permanent electric polarization is imparted to the sensitive element by electronic bombardment within an enclosure wherein prevails a rarefied atmosphere and in which said bombardment is followed with a coating of the so-polarized sensitive element with a film of liquid of very low saturating vapor pressure whose dielectric strength is higher than that of the rarefied air of the enclosure and having advantageously lubricating properties.

Method for manufacturing sensitive elements having a permanent electric

Elongated receiver of continuous structure for seismic prospecting comprising at least one sensitive assembly having two electrically conducting electrodes on both sides of a deformable element subjected to a permanent electric polarization and an electrically insulating compressible element between the deformable element and one of the electrodes. When used for prospecting on the earth the receiver further comprises masses of heavy material secured to one face of the sensitive assembly.

Elongated seismic receiver of continuous structure

The permanent electric polarization is imparted to the sensitive element by electronic bombardment within an enclosure wherein prevails a rarefied atmosphere and in which said bombardment is followed with a coating of the so-polarized sensitive element with a film of liquid of very low saturated vapor pressure whose dielectric strength is higher than that of the rarefied air of the enclosure and having advantageously lubricating properties.

Growing community of inventors

Royan, France

Jean-Claude Dubois