Patent ID: 11860326
Assignee: INSTITUTE OF GEOLOGY AND GEOPHYSICS, CHINESE ACADEMY OF SCIENCES
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 1:
2. The fault characterization method for precise navigation of deep oil and gas based on image fusion as described in claim 1 is characterized in that the spectral shaping comprises:
the original seismic data includes a seismic record convolution model, which is represented in the frequency domain as:

sswa(ω)=σ(ω)ξft(ω)

wherein, sswa(ω) represents a seismic wavelet after the Fourier transform, σ(ω) represents a spectrum of a reflection coefficient after the Fourier transform, ξft represents a spectrum of a reflection coefficient after the Fourier transform, and ω represents an angular frequency;
take a logarithm on both sides of a representation of the convolution model in the frequency domain to obtain a representation of a linear system of seismic records in the frequency domain:

lnsswa(ω)=lnσ(ω)+lnξft(ω)

wherein lnsswa(ω) represents the linear system frequency domain representation of seismic record, lnσ(ω) represents a linear system frequency domain representation of seismic wavelet, and lnξft(ω) represents a linear system frequency domain representation of the reflection coefficient;
carry out inverse Fourier transform on the frequency domain representation of the linear system of the seismic record to obtain a complex cepstrum sequence of a seismic record spectrum:

{tilde over (s)}swa(tswa)={tilde over (σ)}(tswa)+{tilde over (ξ)}ft(tswa)

wherein, {tilde over (s)}swa(tswa) represents a complex cepstrum sequence of seismic waveform record, {tilde over (σ)}(tswa) represents a complex cepstrum sequence of seismic wavelet, {tilde over (ξ)}ft(tswa) represents a complex cepstrum sequence of a stratum reflection coefficient, and tsw represents an arrival time of a seismic wave;
a wavelet complex cepstrum sequence and a reflection coefficient complex cepstrum sequence in the complex cepstrum are separated by a low-pass filter, and a wavelet amplitude is extracted;
based on the wavelet amplitude, simulate a seismic wavelet amplitude spectrum using a least squares method:

σ(f)=A(f)faeH(f)

wherein, the least squares fitting parameter a≥0 is a constant, σ(f) represents the wavelet amplitude spectrum, H(f) and A(f) represent polynomials of f, f represents a frequency of seismic wavelet, and ‘e’ represents a base number of natural logarithm;
based on an amplitude spectrum of the simulated seismic wavelet, a maximum phase component and a minimum phase component of the wavelet is obtained;
if the maximum phase component of the wavelet σ(t) is upc(t) and the minimum phase component is vpc(t) , then the wavelet is σ(t):

σ(t)=upc(t)·vpc(t)

a complex cepstrum of the amplitude spectrum is represented as:

2 {tilde over (σ)}0(t)=ũpc(t)+{tilde over (v)}pc(t)+ũpc(−t)+{tilde over (v)}pc(−t)

wherein, the complex cepstrum of the amplitude spectrum {tilde over (σ)}0(t) is symmetrically displayed on a positive and a negative axis of the complex cepstrum, vpc(−t) is the complex cepstrum of a minimum phase function corresponding to the minimum phase component vpc(t) of the seismic wavelet, ũpc(−t) maximum phase function corresponding to the maximum phase component upc(t) of the seismic wavelet;
based on the complex cepstrum of the amplitude spectrum, determine a set of mixed-phase wavelet sets with a same amplitude spectrum, adjust Yu wavelet parameters, and on a premise of ensuring an integrity of a main frequency of the seismic wavelet, increase an effective bandwidth to a preset bandwidth threshold to obtain the reshaped seismic waveform data.