Abstract: A processing method for calibrating at least one pair of hydrophone-geophone sensors disposed on a water bottom and used in seismic prospecting processing in which a sound source emits a signal into the water and the sensors at the water bottom pick up hydrophone and geophone recordings H and G, wherein calibration is applied to the recordings to minimize, in a time window beyond a theoretical extinction time, the energy of a signal S which is determined as a function of the hydrophone and geophone recordings and which corresponds to the source signal propagated through the layer of water to the sensor.

Abstract: An acoustic emission system for seismic surveying at sea, for the purpose of emitting a soundwave in a given direction, the system comprising firstly a plurality of immersed sources mechanically connected to at least one float means and secondly a control circuit for controlling said sources and comprising a plurality of delay means suitable for applying respective phase delays to each of the sources, said delays being defined by a nominal phase law associated with said given emission direction. According to the invention, the system also includes at least two attitude sensors providing signals representative of the absolute position of at least two of said sources to correction means of said control circuit, said correction means providing each of said delay means with a signal for correcting the nominal phase law and representative of variations in the relative positions of the sources. This system has application to geological prospecting by seismic surveying at sea.

Abstract: A method of correcting a seismic signal s(t) provided by a vibration sensor (100) in response to at least one emission signal F(t) produced by a least one seismic vibration generator (200). The real emission signal F(t) differs in phase and amplitude relative to a reference emission signal F(t). The correction method of the invention consists in determining the phase difference .DELTA..phi.(f) and the amplitude ratio A(f) between the real emission signal F(t) and the reference emission signal F(t) as a function of frequency f, and in applying the seismic signal s(t) from the vibration sensor (100) to a filter (304) whose response is defined in phase and amplitude respectively by -.DELTA..phi.(f) and by 1/A(f).

Abstract: System for interconnecting elements of a receiving device of great length, for example a seismic streamer, comprising a plurality of data aquisition apparatuses, each of which is adapted to collect 12 separate signals generated by receiver groups distributed in the different elements.The 12 groups of separate receivers (R.sub.1, R.sub.2 . . . R.sub.12) are regularly distributed in each element (T.sub.1, T.sub.2 . . . ), forming 6 pairs of groups. A first group of each pair (R.sub.1, R.sub.3, R.sub.5) is connected to an input of an acquisition apparatus (B.sub.2). The second group of each pair is connected either to an input of another acquistion apparatus, or to inactive electric connection means (B.sub.1, B.sub.3) adapted to connect in parallel the second and the first groups of each pair.This system can be used in seismic prospecting.

Abstract: A seismic detector comprises a casing the lower part (10) of which is provided with a plurality of apertures (19). A hydrophone transducer (70) comprising an annular ceramic member provided with metallized surfaces (71,72) is mounted in the casing and defines with the casing an enclosure (65) which houses a geophone (60). The outer face (71) of the hydrophone transducer (70) is subject to the ambient hydrostatic pressure via the apertures (19). The bottom of the casing is provided with a protuberance (11) to which a spike (12) is attached. The seismic detector can work in both hydrophonic and geophonic modes.

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.