Method for the determination of local wave heights and acoustic sensor in marine seismic signals

A method of analyzing received seismic signals which are received from a plurality of seismic sensors in response to operation of an acoustic source during a marine seismic survey, wherein said seismic sensors are located at different offsets from said acoustic source, comprising the steps of:

• selecting a time window within a particular seismic signal which frames a relatively well-defined event represented in the signal, said particular seismic signal being received from a particular seismic sensor;
• determining a receiver ghost notch frequency from an amplitude/frequency spectrum of said seismic signal in said window;
• and
• deriving from said receiver ghost notch frequency an estimate of a height of a water column above said particular seismic sensor which generated said particular seismic signal, wherein deriving the estimate of the height of the water column comprises the steps of:
• identifying changes in arrival times from seismic signals received by the seismic sensors;
• determining time differences between the identified changes in arrival times and expected changes in arrival times associated with an assumed seismic sensor depth profile;
• and
• converting said time differences into depth differences between said assumed seismic sensor depth profile and an actual depth profile of said seismic sensors.

A method of performing a marine seismic survey, comprising the steps of:

• analyzing seismic signals generated by a plurality of submerged seismic sensors in response to operation of an acoustic source during said marine seismic survey, the analyzing step comprising the steps of:
• selecting a time window within a particular seismic signal which frames a relatively well-defined event represented in the signal, a particular sensor adapted to generate said particular seismic signal;
• calculating an amplitude/frequency spectrum of seismic signals generated by said acoustic sensor, wherein said amplitude/frequency spectrum contains both a source ghost notch frequency and a receiver ghost notch frequency;
• determining a receiver ghost notch frequency from an amplitude/frequency spectrum of said seismic signal in said window, wherein determining the receiver ghost notch frequency comprises distinguishing said receiver ghost notch frequency from said source ghost notch frequency on a basis of a relative variability of the receiver ghost notch frequencies and the source ghost notch frequencies;
• and
• deriving from said receiver ghost notch frequency an estimate of a height of a water column above said particular sensor which generated said particular seismic signal.

A method of performing a marine seismic survey, comprising the steps of:

• analyzing seismic signals generated by a plurality of submerged seismic sensors in response to operation of an acoustic source during said marine seismic survey, wherein said seismic sensors are located at different offsets from said acoustic source, the analyzing step comprising the steps of:
• selecting a time window within a particular seismic signal which frames a relatively well-defined event represented in the signal, a particular sensor adapted to generate said particular seismic signal;
• determining a receiver ghost notch frequency from an amplitude/frequency spectrum of said seismic signal in said window;
• and
• deriving from said receiver ghost notch frequency an estimate of a height of a water column above said particular sensor which generated said particular seismic signal, wherein deriving the estimate comprises:
• identifying changes in arrival times from seismic signals received by the seismic sensors;
• determining time differences between the identified changes in arrival times and expected changes in arrival times associated with an assumed seismic sensor depth profile;
• and
• converting said time differences into depth differences between said assumed seismic sensor depth profile and an actual depth profile of said seismic sensors.

A computer apparatus adapted for storing instructions, said instructions, when executed by said computer apparatus, conducting a signal analysis method comprising the steps of:

• analyzing received seismic signals which are generated by a plurality of a seismic sensors in response to operation of an acoustic source during a marine seismic survey, the analyzing step further including the steps of:
• selecting a time window within a particular seismic signal which frames a relatively well-defined event represented in the signal, a particular sensor adapted to generate said particular seismic signal;
• calculating an amplitude/frequency spectrum of seismic signals generated by said acoustic sensor, wherein said amplitude/frequency spectrum contains both a source ghost notch frequency and a receiver ghost notch frequency;
• determining the receiver ghost notch frequency by distinguishing said receiver ghost notch frequency from said source ghost notch frequency on a basis of a relative variability of the receiver ghost notch frequencies and the source ghost notch frequencies;
• and
• deriving from said receiver ghost notch frequency an estimate of a height of a water column above said particular sensor which generated said particular seismic signal.

A computer apparatus adapted for storing instructions, said instructions, when executed by said computer apparatus, conducting a signal analysis method comprising the steps of:

• analyzing received seismic signals which are generated by a plurality of a seismic sensors in response to operation of an acoustic source during a marine seismic survey, wherein said seismic sensors are located at different offsets from said acoustic source, the analyzing step further including the steps of:
• selecting a time window within a particular seismic signal which frames a relatively well-defined event represented in the signal, a particular sensor adapted to generate said particular seismic signal;
• deriving from said receiver ghost notch frequency an estimate of a height of a water column above said particular sensor which generated said particular seismic signal by performing the steps of:
• identifying changes in arrival times from seismic signals received by the seismic sensors;
• determining time differences between the identified changes in arrival times and expected changes in arrival times associated with an assumed seismic sensor depth profile;
• and
• converting said time differences into depth differences between said assumed seismic sensor depth profile and an actual depth profile of said seismic sensors.