Patent ID: 7710821

Claim:
Method for attenuating multiples in marine seismic data, said method comprising the steps of: during a first seismic survey, obtaining a first set of signals representing seismic energy reflected and/or refracted from an earth structure using a first plurality of seismic receivers located in a body of water at a first height above a seafloor; during a second seismic survey, obtaining a second set of signals representing seismic energy reflected and/or refracted from the earth structure using a second plurality of seismic receivers located in the body of water at a second height above the seafloor; wherein: a first condition of the body of water during the first seismic survey is different to a second condition of the body of water during the second seismic survey; and the first and second height are essentially equal or where the first and second heights are different the first and second set of signals are shifted by processing the first and second set of signals to an essentially equal height; separating the first and the second set of signals into up- and down-going wavefields; deghosting the first and second set of signals; and using a processor to process a combination of the first and second set of signals to remove multiples.