US 4,953,657 AGranted

Time delay source coding

AssigneeHalliburton Geophysical Services, Inc.

InventorBruce L. Edington

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Abstract

In seismic exploration, a survey may be conducted using multiple seismic energy sources activated substantially simultaneously. A series of shots is made at each shot point, with a determinable time delay between the activation of each source for each shot. There must be at least two different determinable time delays in each series of shots. The seismic signals are recorded. A method of processing the signals to separate signals from each source is provided. For each signal receiver, the amplitudes of the signals from each shot in the series is summed. The signals are then time shifted, so that the signals from the second source to be activated are received at the same time, and the amplitudes for the series are summed. This step is repeated for each subsequently activated source. Time domain operators are derived, the operators and the summations Fourier transformed to the frequency domain, in which the signals received from each source are readily calculated. The separated signals may then be inverse Fourier transformed to the time domain.

Claims10

Dependent claims

A method of obtaining seismic data for a geophysical survey, said method comprising the steps of:

activating a first seismic energy source having a selected frequency component;
receiving seismic signals from said first seismic energy source at at least one point within said geophysical survey;
activating a second seismic energy source after a first selected time delay from activation of said first seismic energy source and while said seismic signals from said first seismic energy source are being received, said first selected time delay being a nonintegral multiple of the period of said selected frequency component;
receiving seismic signals from said second seismic energy source at said at least one point within said geophysical survey;
activating said first seismic energy source a second time;
receiving seismic signals from said second activation of said first seismic energy source at said at least one point within said geophysical survey;
activating said second seismic energy source after a second selected time delay from said second activation of said first seismic energy source and while said seismic signals from said second activation of said first seismic energy source are being received;
recording, as a function of time, the amplitudes of the seismic signals received at said at least one point within said geophysical survey for each activation of said first and second seismic energy source;
and
analyzing said recorded seismic signal amplitudes utilizing said selected time delays in order to separate signals originating from each of said seismic energy sources.

7 more elements

A method of obtaining seismic data for a geophysical survey, said method comprising the steps of:

activating a first seismic energy source having a selected frequency component;
receiving seismic signals from said first seismic energy source at at least one point within said geophysical survey;
activating a second seismic energy source after a first selected time delay from activation of said first seismic energy source and while said seismic signals from said first seismic energy source are being received, said first selected time delay being a non-integral multiple of the period of said selected frequency component;
receiving seismic signals from said second seismic energy source at said at least one point within said geophysical survey;
activating said first seismic energy source a second time;
receiving seismic signals from said second activation of said first seismic energy source at said at least one point within said geophysical survey;
activating said second seismic energy source after a second selected time delay from said second activation of said first seismic energy source and while said seismic signals from said second activation of said first seismic energy source are being received;
recording, as a function of time, the amplitudes of the seismic signals received at said at least one point within said geophysical survey for each activation of said first and second seismic energy source;
summing the amplitudes of the received seismic signals from each activation as a function of time;
utilizing said selected time delays to time shift the received seismic signals from each activation so that the signals received from said second source are received at the same times for each activation;
summing the amplitudes of said time shifted seismic signals as a function of time;
utilizing said selected time delays to derive an appropriate time domain operator for each summation;
deriving the Fourier transform to the frequency domain of each time domain operator;
deriving the Fourier transform to the frequency domain of each summation;
calculating the signals received from each seismic energy source in the frequency domain for each frequency;
and
deriving the inverse Fourier transform to the time domain of the signals received from each seismic energy source.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/312,360Filed 14 Feb 1989 · continuation
Priority: 30 Nov 1987
Granted: 4 Sep 1990
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01V 1/005
Seismic data acquisition in general, e.g. survey design: with exploration systems emitting special signals, e.g. frequency swept signals, pulse…
G01V 1/37
Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy:…
G01V 2210/127
Signal generation: cooperating multiple sources
G01V
Geophysics