Seismic Inversion by Multispectral Recursive Wavelet Summation
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Transcript of Seismic Inversion by Multispectral Recursive Wavelet Summation
Rapid variation of impedance.
Sparse Spike Inversion.
Smooth variation of impedance.
Other methods preferred.
* The inversion is a 8.5 million cells spreadsheet!!!!REFLECTIVITY
SEISMIC Trace
IMPEDANCE
Reconstructed Seismic trace by
Recursive Wavelet Summation
Reflectivity from Inversion True Reflectivity
Difference
Input Data
After 1017 iterations
50 msBed Thickness < 5 ms
Inverted Impedance
TRUE IMPEDANCE
Input Data
True Reflectivity
Reflectivity from Inversion
Reconstructed Seismic trace by
Recursive Wavelet Summation
Difference
Bed Thickness < 5 ms
50ms
Input Data
True Reflectivity
Reflectivity from Inversion
Reconstructed Seismic trace by
Recursive Wavelet SummationDifference
50ms
Smoothed spectrum of the
seismic trace used as the
main wavelet
Low Residual
The reconstructed waveform is almost PERFECTLY identical to the original seismic trace.
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Note the improvements from
the MULTISPECTRAL solution
* We may have been too aggressive in computing the high frequency normalizing filter
Between 18Hz and 190Hz the Pearson Coefficient are > 0.8
The multispectral RWS inversion has recovered the FULL
BANDWIDTH of the seismic data between 18 and 190 HZ!
Note the gain in the high frequencies
The RED curve is the original seismic trace. The BLACK curve is the TRUE reflectivity convolved with the BP wavelet. The BLUE curve is the reflectivity
from the Multispectral RWS inversion convolved with the same BP wavelet.
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RINV1 RINV2
Note the different scale for CONV2 and RINV2
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Frequency
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Note how the character of the Multispectral RWS inversion follows the
true reflectivity at the very low end. However, the amplitude is higher
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MAIN W
FFT 70Hz Ricker
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MAIN
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ALPHA (4Hz
Window)
PEARSON (4Hz
Window)
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AUTO CORRELATION
MAIN W
FFT 70Hz Ricker
DOUBLE FFT
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AUTO CORRELATION
MAIN W
DOUBLE FFT
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AUTO CORRELATION
MAIN W
DOUBLE FFT
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FFT(R2) Rc Smooth
Raw and Smoothed spectra of calibrated inverted reflectivity
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70Hz Ricker
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W/Rc Smooth
Rc Smooth
Note that W2
will
need to be tapered
between 0 and 15Hz