초록 ▼

A method of separating the effects of the earth response on vibratory energy from individual ones of multiple vibrators to geophones, in generating a seismic survey, is disclosed. According to the disclosed method, measurements of the actual vibrations generated at the source are made, in addition t

A method of separating the effects of the earth response on vibratory energy from individual ones of multiple vibrators to geophones, in generating a seismic survey, is disclosed. According to the disclosed method, measurements of the actual vibrations generated at the source are made, in addition to the geophone measurements of the refracted and reflected vibrations, both over a number of frequency sweeps. The source and geophone vibrations are first transformed into frequency domain representations, by way of Discrete Fourier Transforms. An inverse matrix of the recorded frequency-domain source vibrations is then generated for each frequency. When the number of sweeps equals the number of vibrators, the inverse matrix is merely the multiplicative inverse of the source measurements; if the number of sweeps exceeds the number of vibrators, the inverse matrix is the generalized inverse of the original matrix. The inverse matrix for the frequency is applied to the recorded geophone vibrations at that frequency, to derive the transfer function, corresponding to the earth response, for each vibrator-geophone path in the survey. A weighting factor may be used to discount the effects of poorly behaved sweeps, and may be based on the ratio of the maximum and minimum eigenvalues for the inverse matrix.

대표청구항 ▼

[ We claim:] [14.] A method of generating a seismic survey based upon previously obtained vibratory seismic measurements including measurements of source vibrations from at or near vibrators located at the surface of the earth that are simultaneously energized over a plurality of sweeps, and measure

[ We claim:] [14.] A method of generating a seismic survey based upon previously obtained vibratory seismic measurements including measurements of source vibrations from at or near vibrators located at the surface of the earth that are simultaneously energized over a plurality of sweeps, and measurements of detected vibrations from detector locations spaced away from the vibrators, the previously obtained vibratory seismic measurements being stored in digital form in a computer memory, comprising:determining earth response transfer functions for each seismic path between one of the plurality of vibrators and one of the plurality of detecting locations, by operating a computer to perform the steps of:retrieving, from computer memory, the stored representations of the measured source vibrations and measured field vibrations;transforming the stored representations of the measured source vibrations and measured field vibrations into frequency domain representations;defining a first matrix of the frequency domain representation of the measured source vibrations at a frequency, and a second matrix of the frequency domain representation of the detected vibrations at the frequency;determining an inverse of the first matrix;multiplying the second matrix by the inverse of the first matrix to derive the earth response transfer functions at the frequency; andrepeating the defining, determining, and multiplying steps for a plurality of frequencies; andgenerating a seismic survey using the derived earth response transfer functions over a plurality of frequencies.