Determination of reflectivity and water depth for marine seismic exploration

Claim 1

In marine seismic exploration which includes: firing at least one source in an array of sources towed by a marine vessel, recording seismograms representing the reflected seismic pulses, measuring the water bottom reflectivity and the water depth from the recorded seismograms, converting the measurements of reflectivity and water depth into a time domain operator representative of the inverse of the reverberaion distortion in the water layer between the water bottom and water surface, and thereafter firing said array of sources in groups such that the acoustic pulses from each of said sources combine to produce a resultant acoustic pressure wave having said time domain operator characteristic in its travel to and from the subsurface formation, the improvement wherein said measuring comprises the steps of: generating the zero lag auto-correlation coefficients of a window of said seismogram, generating the auto-correlation coefficients of said window with a lag of n time samples, generating the auto-correlation coefficients of said window with a lag of 2n time samples, repeating the foregoing for various values of n, combining the auto-correlation coefficients generated for each value of n, and selecting the n producing the minimum in the combined auto-correlation functions as being representative of water depth.