Shaped-sweep technology

Claim 1

A method for producing seismic wavelet shapes with minimal side lobe energy, which method comprises: a. selecting a power spectrum from the group consisting of spectra which are derivatives of Gaussian functions and their substantial equivalents within the frequency range of about 0.5 f p Hz to about 2.0 f p Hz, where f p is the frequency at which the spectrum peaks, and is set between about 10 Hz and about 80 Hz; b. computing a spectrally shaped sweep for said power spectrum so that the Fourier transform of said sweep's autocorrelation is substantially the same as that of the spectrum; c. using said spectrally shaped sweep as a reference signal for driving a seismic vibrator; d. using said vibrator to impart vibrations to the earth; e. collecting seismic data from the earth, which data result from said vibrations; and f. deconvolving the seismic data with the reference signal.

Claim 2

A method for producing seismic wavelet shapes with minimal side lobe energy, which method comprises: a. selecting a power spectrum from the group consisting of spectra which are derivatives of Gaussian functions and their substantial equivalents within the frequency range of about 0.5 f p Hz to about 2.0 f p Hz, where f p is the frequency at which the spectrum peaks, and is set between about 10 Hz and about 80 Hz; b. computing a spectrally shaped sweep for said power spectrum so that the Fourier transform of said sweep's autocorrelation is substantially the same as that of the spectrum; c. using said spectrally shaped sweep as a reference signal for driving a seismic vibrator; d. using said vibrator to impart vibrations to the earth; e. collecting seismic data from the earth, which data result from said vibrations; and f. deconvolving the seismic data with the reference signal.

Claim 3

A method for producing seismic wavelet shapes with minimal side lobe energy, which method comprises: a. selecting a power spectrum from the group consisting of the following equation and its substantial equivalents: ##EQU9## wherein P(f) is the desired power spectrum, K is an arbitrary constant used to scale the equation, f is the frequency of the sweep in Hertz, ranging from about 0.5 f p Hz to about 2.0 f p Hz, f p is the frequency at which the spectrum peaks, and is set between about 10 Hz and about 80 Hz, m is a constant which defines the function type, where m is not necessarily an integer, and n is the order of the derivative, where n is not necessarily an integer; b. computing a spectrally shaped sweep for said power spectrum so that the Fourier transform of said sweep's autocorrelation is substantially the same as that of said power spectrum; c. using said spectrally shaped sweep as a reference signal for driving a seismic vibrator; d. using said vibrator to impart vibrations to the earth; e. collecting seismic data from the earth, which data result from said vibrations; and f. deconvolving the seismic data with said reference signal.

Claim 4

A method for producing seismic wavelet shapes with minimal side lobe energy, which method comprises: a. selecting a power spectrum from the group consisting of the following equation and its substantial equivalents: ##EQU9## wherein P(f) is the desired power spectrum, K is an arbitrary constant used to scale the equation, f is the frequency of the sweep in Hertz, ranging from about 0.5 f p Hz to about 2.0 f p Hz, f p is the frequency at which the spectrum peaks, and is set between about 10 Hz and about 80 Hz, m is a constant which defines the function type, where m is not necessarily an integer, and n is the order of the derivative, where n is not necessarily an integer; b. computing a spectrally shaped sweep for said power spectrum so that the Fourier transform of said sweep's autocorrelation is substantially the same as that of said power spectrum; c. using said spectrally shaped sweep as a reference signal for driving a seismic vibrator; d. using said vibrator to impart vibrations to the earth; e. collecting seismic data from the earth, which data result from said vibrations; and f. deconvolving the seismic data with said reference signal.