Method and device for determining the remote emission signature of a seismic emission assembly

Claim 1

A method of determining the remote signature of an emission array emitting seismic pulses in water and comprising a plural number N of seismic sources, comprising: measuring the emission signatures of each of the N sources actuated separately, one at a time, prior to the use of the emission array, for different values of parameters influencing the form of the pulses produced by the source, by means of respective sensors disposed in the vicinity of each of the N sources and storing said emission signatures in the form of a catalogue of all the measurements made successively for all of the sources of the emission array in accordance with each of the differnt values of parameters employed; measuring the effective values of these same parameters for all the sources, at the time of the combined use thereof; selecting emission signatures from the catalogue of the respective emission signatures of the N sources of the emission array corresponding to the effective value measured for said parameters; and determining the overall remote emission signature of the emission array by effecting a linear combination of the N emission signatures selected from the catalogue, taking into account the effective firing times of the different sources.

Claim 2

A method of determining the remote signature of an emission array emitting seismic pulses in water and comprising a plural number N of seismic sources, comprising: measuring the emission signatures of each of the N sources actuated separately, one at a time, prior to the use of the emission array, for different values of parameters influencing the form of the pulses produced by the source, by means of respective sensors disposed in the vicinity of each of the N sources and storing said emission signatures in the form of a catalogue of all the measurements made successively for all of the sources of the emission array in accordance with each of the differnt values of parameters employed; measuring the effective values of these same parameters for all the sources, at the time of the combined use thereof; selecting emission signatures from the catalogue of the respective emission signatures of the N sources of the emission array corresponding to the effective value measured for said parameters; and determining the overall remote emission signature of the emission array by effecting a linear combination of the N emission signatures selected from the catalogue, taking into account the effective firing times of the different sources.

Claim 5

The method as claimed in one of the preceding claims, wherein the immersion depth of each of the sources is determined by combining the depth measurements made before and after the emission of each seismic pulse.

Claim 7

A system for determining the remote signature of an emission array emitting seismic pulses in water comprising a plural number N of seismic sources; reception means for picking up the sound waves emitted by the N seismic sources for effecting seismic prospecting, including a respective sensor disposed in the vicinity of each seismic source; and a data acquisition device including means for amplifying signals received from said reception means with a selected gain, means for digitizing the amplified signals and for recording the digitized signals so that the values of signals with different gains from the same sensor are associated, means for storing emission signatures in the form of a catalogue of signatures stored in accordance with associated values of parameters related to said signatures, processing means for processing said digitized signals on the basis of said stored emission signatures, and selection means for applying to said digitization and recording means signals provided by said sensors that are amplified with a different gain depending on whether the signal relates to emersion depth of the source or its emission signature, wherein said amplification means comprises two amplifiers for amplifying concurrently the signals delivered by each sensor, and said selection means comprises a switch actuated by said digitization and recording means before and after emission of each seismic pulse.

Claim 8

A system for determining the remote signature of an emission array emitting seismic pulses in water comprising a plural number N of seismic sources; reception means for picking up the sound waves emitted by the N seismic sources for effecting seismic prospecting, including a respective sensor disposed in the vicinity of each seismic source; and a data acquisition device including means for amplifying signals received from said reception means with a selected gain, means for digitizing the amplified signals and for recording the digitized signals so that the values of signals with different gains from the same sensor are associated, means for storing emission signatures in the form of a catalogue of signatures stored in accordance with associated values of parameters related to said signatures, processing means for processing said digitized signals on the basis of said stored emission signatures, and selection means for applying to said digitization and recording means signals provided by said sensors that are amplified with a different gain depending on whether the signal relates to emersion depth of the source or its emission signature, wherein said amplification means comprises two amplifiers for amplifying concurrently the signals delivered by each sensor, and said selection means comprises a switch actuated by said digitization and recording means before and after emission of each seismic pulse.

Claim 10

A system for determining the remote signature of an emission array emitting seismic pulses in water comprising a plural number N of seismic sources; reception means for picking up the sound waves emitted by the N seismic sources for effecting seismic prospecting, including a respective sensor disposed in the vicinity of each seismic source; and a data acquisition device including means for amplifying signals received from said reception means with a selected gain, means for digitizing the amplified signals and for recording the digitized signals so that the values of signals with different gains from the same sensor are associated, means for storing emission signatures in the form of a catalogue of signatures stored in accordance with associated values of parameters related to said signatures, processing means for processing said digitized signals on the basis of said stored emission signatures, and selection means for applying to said ditigization and recording means signals provided by said sensors that are amplified with a different gain depending on whether the signal relates to emersion depth of the source or its emission signature, wherein said amplification means comprises a single variable gain amplifier for amplifying the signals delivered by each sensor, and said selection means comprises an element actuated by said digitization and recording means for generating a control signal for giving alternately two different values to the gain of said amplifier.

Claim 11

A system for determining the remote signature of an emission array emitting seismic pulses in water comprising a plural number N of seismic sources; reception means for picking up the sound waves emitted by the N seismic sources for effecting seismic prospecting, including a respective sensor disposed in the vicinity of each seismic source; and a data acquisition device including means for amplifying signals received from said reception means with a selected gain, means for digitizing the amplified signals and for recording the digitized signals so that the values of signals with different gains from the same sensor are associated, means for storing emission signatures in the form of a catalogue of signatures stored in accordance with associated values of parameters related to said signatures, processing means for processing said digitized signals on the basis of said stored emission signatures, and selection means for applying to said ditigization and recording means signals provided by said sensors that are amplified with a different gain depending on whether the signal relates to emersion depth of the source or its emission signature, wherein said amplification means comprises a single variable gain amplifier for amplifying the signals delivered by each sensor, and said selection means comprises an element actuated by said digitization and recording means for generating a control signal for giving alternately two different values to the gain of said amplifier.