Compagnie Generale De Geophysique

Kietta

Seabed Geosolutions B.v.

Compagnie General De Geophysique

Michel G Manin

Luc Haumonte

Frederic Schom

Divine Maalouf

Peter Weiss

Jean-Paul Carle

Denis Greffet

A seismic marine vibrator () may comprises first plates () and second plates () arranged along a longitudinal axis (), longitudinal and peripheral first () and second () elements respectively secured to the first () and second () plates, and an actuator () operable to reciprocate the first elements () relative to the second elements () along the longitudinal axis () so as to reciprocate the first plates () relative to the second plates (). The seismic marine vibrator further comprises peripherally closed air-filled chambers () and peripherally open chambers (), the volume of said open chambers () being varied when the first plates () are reciprocated so as to take in and expel water radially to generate an acoustic wave. This forms an improved seismic marine vibrator.

Seismic marine vibrator

The invention in particular relates to a method for controlling the horizontal position of a seismic cable adapted for acquiring seismic data midwater. The method comprises, based on a deviation observed between the position of the seismic cable and a setpoint horizontal position, a correction of the position of the seismic cable through an adjustment of the forces respectively exerted by lead-in cables on the ends of the seismic cable, the exerted forces simultaneously and each having an axial component and a lateral component relative to the seismic cable at at least one moment of the correction. This allows an easy to implement and relatively precise control of the horizontal position of a seismic cable adapted for acquiring seismic data midwater and kept stationary or quasi-stationary during the data acquisition.

Control of the horizontal position of a seismic cable

A method for seismic prospecting in an aquatic medium using a device having at least one seismic cable provided with sensors and at least one moving seismic source. The method includes the following steps: 1) moving the cable in the water using two drones each placed at one end of the cable and which maintain tension in the cable, the movement of the cable minimizing the deviation of the cable with respect to a desired route in the terrestrial reference frame where the movement of the cable is also being restricted by a maximum track curvature value in the water, and, at the same time; and 2) moving the seismic source in a reference frame connected to the cable, emitting waves via the seismic source, and sensing reflections of the waves by the cable.

Method of deployment, method and device for seismic prospecting in an aquatic medium

A system for aquatic seismic prospecting includes at least one submerged mobile seismic source for creating a disturbance transmitted through an aquatic medium in the form of waves and at least one cable having a plurality of sensors for collecting waves transmitted by the at least one submerged mobile seismic source and reflected from geological layers beneath the aquatic medium. The system also includes means for detecting and measuring the reflected waves and means for placing the at least one cable under tension, the tensioning means attached to ends of the at least one cable and the tensioning means keeping the at least one cable in a pseudo-stationary position. These is also means for holding the at least one cable at a substantially constant depth greater than approximately 5 meters.

Enhanced method and device for aquatic seismic prospecting

A system for seismic exploration of a submerged sub-surface comprises a plurality of bases () located at predetermined seabed positions, each base comprising an elongate stem penetrating the seabed, at least a seismic sensor () within said stem, a radially extending support zone () connected to the upper end of the stem, said upper end projecting from the seabed, and a respective plurality of modules () each incorporating a data storage unit and a power source, each module being mechanically and electrically connected to the upper end of said stem, said module being capable of being connected to, and disconnected from, the base by an underwater vehicle.

System for seismic exploration a submerged subsurface including implanted bases

An off-shore seismic prospecting method for enabling at least two ships to prospect over a single site simultaneously, in which each of the ships generates disturbances in the off-shore environment and uses sensors to record seismic traces containing useful information concerning the geology of the subsoil. A ship is liable to constitute a point source of noise for another ship, which noise gives rise to an undesirable signal that masks said useful information. According to the invention said point source of noise is localized in three dimensions and the space-time coordinates thereof [(X'(t), Y'(t), Z(t)] during the recording is stored in terms of a frame of reference in which the space-time coordinates [(X.sub.r (t), Y.sub.r (t), Z.sub.r (t)] of the sensors are also recorded, after which the recorded seismic traces are processed as a function of the space-time coordinates of the point source of noise in order to eliminate said undesirable signal.

Method of off-shore seismic prospecting

The invention relates to a method and apparatus for processing data from a seismic survey. In accordance with the invention, the data is regrouped to form a plurality of seismic images (A1, A2, A3, B1, B2, B3, C1, C2, C3). These images being defined by image elements defined in spatial position with respect to an operation direction (D) and having a grey level of predetermined amplitude, the method consisting for each pair of images (Ai,Bj) of carrying out processing by correlation of the amplitude of the grey levels, in order to establish an intercorrelation coefficient and to compensate the localization errors in the position of the images. Application to mono-, bi- or tri-dimensional marine geophysical prospecting.

Method and apparatus for processing seismographic data by correlation

The present invention relates to a method for initiating an underwater implosive seismic source which comprises the steps of: measuring the instantaneous pressure at the location of the source; determining, from this measured pressure, the bubble period separating the firing signal from the implosion peak of the shock wave; and initiating the source with a delay or advance of a value equal to the difference between the bubble period corresponding to the instantaneous pressure and that corresponding to the mean pressure. The invention also provides a device for carrying out this method which device comprises; means for measuring the instantaneous pressure in the neighborhood of the source; comparator means (C5) for comparing this pressure with a mean value; and time delay means (C3, C4) for delaying a firing signal (S1) by a value which is a function of the result of this comparison.

Method and device for initiating an underwater implosive seismic source

The invention relates to seismic sources in which a shock wave is produced in a liquid mass by the implosion of a volume of vapor, particularly water vapor. According to the invention, the vapor to be imploded is formed inside a closed, flexible enclosure, surrounding an injection head, fitted with a vapor opening 103 capable of releasing vapor at 5 bars and 170.degree. C., controlled by an electromagnetic valve. Liquid nuclei are advantageously introduced into this vapor by means of a pipe for cold water which is under pressure and under the control of an electromagnetic valve, this water arriving in the cavity in order to exit through spray openings. These nuclei produce a vigorous drop in pressure inside the vapor, and hence an implosion and a shock wave, after which a pipe allows the condensate to be recovered. The invention is of use notably as a seismic marine source.

Vapor implosion in a closed flexible enclosure

The invention relates to the creation of a shock wave within a mass of water by implosion of a vapor bubble. According to the invention, a controlled quantity of liquid water under pressure and which is super-heated relative to the mass of water is released quickly, at a predetermined point of the mass of water, the water advantageously being in the lower vicinity of the left-hand part of the saturation curve (portion B-D). The water liberated in this way expands and vaporizes at least partially in the form of a single bubble, which then implodes suddenly. Application as a marine seismic source.

Generation of seismic sources

The invention concerns a process for seismic exploration. It consists in simultaneously emitting disturbances from a plurality of sources S1 . . . Sn immersed at various depths and positions chosen so as to maximize the power transmitted vertically and to minimize the power transmitted in certain determined oblique directions. The reflected or refracted seismic signals are gathered by hydrophones. By this means certain parasitic refractions are eliminated.

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Massy, France

Michel G Manin