Abstract: A seismic marine vibrator (100) may comprises first plates (102) and second plates (104) arranged along a longitudinal axis (101), longitudinal and peripheral first (106) and second (108) elements respectively secured to the first (102) and second (104) plates, and an actuator (112) operable to reciprocate the first elements (106) relative to the second elements (108) along the longitudinal axis (101) so as to reciprocate the first plates (102) relative to the second plates (104). The seismic marine vibrator further comprises peripherally closed air-filled chambers (109) and peripherally open chambers (111), the volume of said open chambers (111) being varied when the first plates (102) are reciprocated so as to take in and expel water radially to generate an acoustic wave. This forms an improved seismic marine vibrator.

Abstract: A seismic marine vibrator (100) may comprises first plates (102) and second plates (104) arranged along a longitudinal axis (101), longitudinal and peripheral first (106) and second (108) elements respectively secured to the first (102) and second (104) plates, and an actuator (112) operable to reciprocate the first elements (106) relative to the second elements (108) along the longitudinal axis (101) so as to reciprocate the first plates (102) relative to the second plates (104). The seismic marine vibrator further comprises peripherally closed air-filled chambers (109) and peripherally open chambers (111), the volume of said open chambers (111) being varied when the first plates (102) are reciprocated so as to take in and expel water radially to generate an acoustic wave. This forms an improved seismic marine vibrator.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A system for seismic exploration of a submerged sub-surface comprises a plurality of bases (4) located at predetermined seabed positions, each base comprising an elongate stem penetrating the seabed, at least a seismic sensor (10, 12) within said stem, a radially extending support zone (19) connected to the upper end of the stem, said upper end projecting from the seabed, and a respective plurality of modules (6) 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.

Abstract: 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.

Abstract: Enhanced method and device for aquatic seismic prospecting of the type in which:—a submerged mobile seismic source is positioned, able to create one or more disturbances transmitted through the aquatic medium in the form of waves able to be reflected on the bottom of the water and the different deep underlying geological layers;—at least one cable, and preferably several, provided with a plurality of sensors is positioned, able to collect said reflected waves;—said seismic source is triggered with one or more repeats thus creating one or more disturbances;—said reflected waves are picked up using said sensors.

Abstract: A system for seismic exploration of a submerged sub-surface comprises a plurality of bases (4) located at predetermined seabed positions, each base comprising an elongate stem penetrating the seabed, at least a seismic sensor (10, 12) within said stem, a radially extending support zone (19) connected to the upper end of the stem, said upper end projecting from the seabed, and a respective plurality of modules (6) 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.