System for marine seismic exploration
First Claim
1. A system for marine seismic exploration of underground structures beneath the sea bottom being covered by a mass of water having a water surface, comprising a transmitter means having an array of acoustic transducers for generating acoustic waves in the water, and a receiver means for detecting an acoustic wave pattern formed on the water surface by the acoustic waves reflected from said underground structures,wherein said acoustic transducers are mutually phase locked sine-wave generators producing a number of mutually coherent monochromatic acoustic waves of different frequencies, andwherein said receiver means comprises a continuous wave radar illuminating said acoustic wave pattern with monochromatic electromagnetic waves of at least one frequency adapted to be reflected by the acoustic wave pattern;
- and wherein said continuous wave radar comprises narrowband receiver circuits tuned to at least one frequency corresponding to a frequency shift imparted to reflected electromagnetic waves in relation to said illuminating electromagnetic waves du to the Doppler effect caused by motion of said acoustic wave pattern along said water surface, said receiver means further comprising a processor unit adapted to determine phase and relative amplitudes of said reflected acoustic waves on the basis of said reflected, frequency-shifted electromagnetic waves, so as to thereby obtain a recording of said underground structures.
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Abstract
System for seismic profiling of structures (2) beneath the sea bottom, comprising an acoustic transducer array (12) which synchronously and coherently generates an acoustic wave adapted to be reflected from said structures (2). When the reflected acoustic waves propagate towards the water surface (1), there is caused a perturbation of the electromagnetic reflection coefficient thereof. Receiver means for detection and characterization of the received acoustic field at the surface (1), comprises a radar system (10) illuminating the region concerned of the surface (1) and imposes thereat a number of interferograms each corresponding to the acoustic field from a scattering point given by the position thereof and the frequency of the field. By recording the degree of coincidence between the interferograms and the acoustic perturbation pattern on the water surface (1), the seismic properties of said structures (2) are surveyed.
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Citations
15 Claims
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1. A system for marine seismic exploration of underground structures beneath the sea bottom being covered by a mass of water having a water surface, comprising a transmitter means having an array of acoustic transducers for generating acoustic waves in the water, and a receiver means for detecting an acoustic wave pattern formed on the water surface by the acoustic waves reflected from said underground structures,
wherein said acoustic transducers are mutually phase locked sine-wave generators producing a number of mutually coherent monochromatic acoustic waves of different frequencies, and wherein said receiver means comprises a continuous wave radar illuminating said acoustic wave pattern with monochromatic electromagnetic waves of at least one frequency adapted to be reflected by the acoustic wave pattern; and wherein said continuous wave radar comprises narrowband receiver circuits tuned to at least one frequency corresponding to a frequency shift imparted to reflected electromagnetic waves in relation to said illuminating electromagnetic waves du to the Doppler effect caused by motion of said acoustic wave pattern along said water surface, said receiver means further comprising a processor unit adapted to determine phase and relative amplitudes of said reflected acoustic waves on the basis of said reflected, frequency-shifted electromagnetic waves, so as to thereby obtain a recording of said underground structures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
Specification