Method of compensating seismic data for effects of frequency dependent attenuation
OwnerJames F. Nichols, Peter P. Van Bemmelinventors
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Abstract
In one exemplar embodiment, an improved method is provided for compensating received propagated seismic signals for the absorption by the earth of all frequencies of a vibrator source signal. The received seismic data is crosscorrelated with the original source signal and a Fourier amplitude spectral analysis obtained. Then an attenuation function is determined by the attenuation exhibited by the spectrum. The quantified attenuation function is then applied as a compensation function to the original source signal to obtain a "weighted" vibrator sweep signal that is then used in crosscorrelating with the received seismic data to compensate for the frequency dependent attenuation in the earth of received propagated seismic data.
Claims11
A process for compensating received propagated seismic signals for frequency dependent absorption in the earth, wherein such signals have been generated by a vibrator source and propagated in the earth as a transmitted sweep signal, and wherein a recorded sweep signal has been recorded as a counterpart to the transmitted sweep signal, comprising the steps of
- producing correlated data obtained by crosscorrelating said received propagated seismic signals with said recorded sweep signal,
- determining a plurality of Fourier amplitude spectra for said correlated data,
- establishing an average quantitative amplitude attenuation function from said Fourier amplitude spectra for all frequencies contained in the recorded sweep signal,
- converting said amplitude attenuation function to an inverse amplitude function for compensation of the attenuation for all frequencies contained in the recorded sweep signal,
- applying said inverse amplitude function to the recorded sweep signal to obtain a weighted sweep signal for use in correlation, and
- producing attenuation compensated correlated data obtained by crosscorrelating said received propagated seismic signals with said weighted sweep signal.
A process for compensating received propagated seismic signals for frequency dependent absorption in the earth, wherein such signals have been generated by a vibrator source and propagated in the earth as a transmitted sweep signal, and wherein a recorded sweep signal has been recorded as a counterpart to the transmitted sweep signal, comprising the steps of
- producing correlated data obtained by crosscorrelating said received propagated seismic signals with said recorded sweep signal,
- determining a plurality of Fourier amplitude spectra for said correlated data,
- fitting a curve to the maxima and minima of each of said fourier amplitude spectra at all frequencies of the recorded sweep signal, each of said curves varying slowly with frequency,
- averaging the attenuation function values obtained from said plurality of curves to establish an average quantitative attenuation function for all frequencies contained in the recorded sweep signal,
- converting said attenuation function to an inverse amplitude function for compensation of the attenuation for all frequencies contained in the recorded sweep signal,
- applying said inverse amplitude function to the recorded sweep signal to obtain a weighted sweep signal for use in correlation, and
- producing attenuation compensated correlated data obtained by crosscorrelating said received propagated seismic signals with said weighted sweep signal.
Dependencies are inferred from the claim text.