| Vibroseis scanning technology can be divided into linear scanning and nonlinear scanning according to the variation of frequency with time.Linear and nonlinear refer to the variation of scanning frequency with time.The autocorrelation function of the linear scan signal,although having a distinct main lobe,has a larger first side lobe amplitude and wake oscillation,and appears as correlated noise on the seismic record.Aiming at the problem of low signal-to-noise ratio and low resolution of linear scanning signals,a nonlinear scanning signal is proposed.In this paper,a variety of nonlinear functions are used to fit the instantaneous frequency curve,and the nonlinear scanning signal is designed to analyze the influence of different proportions of low-frequency energy on the resolution of the scanning signal.The function,the pulse function,has the highest resolution,which is infinitely narrow in the time domain and infinitely wide in the frequency domain.In this paper,the Morlet wavelet is used for full-band decomposition of the function.The reconstructed scale is selected according to the frequency range of the scanned signal and the partial frequency band is reconstructed.The reconstructed result is the ideal scan signal.The wavelet has a main lobe narrow.Energy concentration and small side lobe amplitude.The amplitude spectrum of the reconstructed wavelet is used as the ideal scanning signal amplitude spectrum,and the nonlinear scanning signal is designed according to the correspondence between the amplitude spectrum of the scanning signal and the instantaneous frequency curve.At the end of the paper,the designed data is used to perform spectral shaping on the actual data.The shaped seismic section has higher resolution than the original seismic section and has higher fidelity than the spectrally whitened seismic section.It is further verified that the correlated wavelet of the nonlinear scanning signal designed in this paper not only has higher resolution but also has higher fidelity. |
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