SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos...
-
Upload
jeffery-oconnor -
Category
Documents
-
view
212 -
download
0
Transcript of SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos...
![Page 1: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/1.jpg)
SISMOwww.sismo.srv.br
Can we use the spectral ridges to estimate Q ?
Marcílio Castro de Matos
[email protected] www.matos.eng.br
1
Attribute-Assisted Seismic Processing and Interpretation
http://geology.ou.edu/aaspi/ Signal Processing Research, Training & Consultingwww.sismo.srv.br
![Page 2: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/2.jpg)
Summary
• Spectral ridges• Q estimation• Examples• Conclusions
SyntheticReflectivity CWT Magnitude
CWTmagnitude
0
pos
CWT MML
![Page 3: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/3.jpg)
Spectral ridges
Introduction
Continuous Wavelet Transform (very brief review)
ICWTdec
Examples
Conclusions
3
![Page 4: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/4.jpg)
Tim
e F
requ
ency
Reflectivity
r(t)
Source wavelet
s(t)
Noise
n(t)
Seismic data
u(t)* +
Bandlimited white spectrum
Modified from Kurt Marfurt course(Partyka et al, 1999)
Long window spectral
decomposition and the
convolutional model
White spectrum
![Page 5: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/5.jpg)
Colored spectrum
Tim
e F
requ
ency
Reflectivity
r(t)
Source wavelet
s(t)
Noise
n(t)
Seismic data
u(t)* +
Bandlimited colored spectrum
Short window spectral
decomposition and the
convolutional model
Modified from Kurt Marfurt course(Partyka et al, 1999)
![Page 6: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/6.jpg)
1822 Fourier book
From: http://books.google.com/
TeFtf
k
tjkkT
2.)( 0
0
Tt
t
tjkk dtetfT
F0
0
0 .).(1
Animated plot of the first five successive partial Fourier series. From wikipedia.org
f t t
![Page 7: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/7.jpg)
(Yilmaz, 2001)
Seismic zero phase wavelet
Summation of co-sinusoids with zero phase
f t t
![Page 8: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/8.jpg)
8
Short Time Fourier Transform – STFT
The simplest time-frequency representation
duetuhuxhtF ujx
2*;,
f t t
![Page 9: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/9.jpg)
9
Short Time Fourier Transform – STFTAmplitude and Phase spectrum
![Page 10: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/10.jpg)
tim
e
20 40 60 80 100 120 140 160 180 200 220
2000
2200
2400
2600
2800
3000
3200-2
-1
0
1
2
x 104
frequency
tim
e
0 50 100 150 200
2000
2200
2400
2600
2800
3000
3200
Time-frequency pattern???
f t t
![Page 11: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/11.jpg)
Spectral ridges
Introduction
Continuous Wavelet Transform (very brief review)
ICWTdec
Examples
Conclusions
11
![Page 12: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/12.jpg)
Continuous Wavelet Transform
0 1 2 3 4 5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
tempo
Am
plitu
de
0.02 0.04 0.06 0.08 0.1 0.12 0.14
0
2
4
6
8
10
12
14
16
18
frequencia normalizada (x )
Am
plit
ude
Cdd0 2
0
2 ˆˆ
0
dtt
s
ut
stsu 1
, 00ˆ
dtt
-5 -4 -3 -2 -1 0 1 2 3 4 5-0.4
-0.2
0
0.2
0.4
0.6
0.8
1Wavelet Chapeu Mexicano
tempo
Am
plitu
de
(x) L2() is called a wavelet
![Page 13: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/13.jpg)
100 200 300 400 500 600 700 800 900 1000
-0.2
0
0.2
0.4
Amostras
Am
plitu
de
Amostras
Esc
ala
100 200 300 400 500 600 700 800 900 1000
10
20
30
40
50
60
Continuous Wavelet Transform (CWT)
time
Amplitude
( ),
1( , ) ( , ) , ( )x u s
t uCWT u s Wf u s f f t dt
ss
1
( , ) ( ) s
t uWf u s f t dt f u
ss
s
t
sts 1
ˆ ˆs s s The CWT can be interpreted
as a band pass filter response at each scale s
Sca
les
Time (ms)
Time (ms)
f t t
![Page 14: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/14.jpg)
Grossmann and Morlet introduced CWT formally
in 1984
![Page 15: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/15.jpg)
Inverse CWT
SyntheticReflectivity CWT Magnitude Voices ICWT
CWTmagnitude
0
pos
Σ
![Page 16: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/16.jpg)
Summary
Introduction
Continuous Wavelet Transform (very brief review)
Pseudo deconvolution (icwtdec)
Examples
Conclusions
16
![Page 17: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/17.jpg)
Math behind…
![Page 18: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/18.jpg)
100 200 300 400 500 600 700 800 900 1000
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
amostras
Am
plitude
20
40
60
80
100
120
Abs. and by scale Values of Ca,b Coefficients for a = 1 2 3 4 5 ...
time (or space) b
scal
es a
100 200 300 400 500 600 700 800 900 1000 1 5 913172125293337414549535761
100 200 300 400 500 600 700 800 900 1 5 913172125293337414549535761
Local Maxima Lines
Singularities detection and characterization through Continuous Wavelet Transform (CWT): Lipschitz (Hölder) Coefficients
10 20 30 40 50 60
1
2
3
s
|Wf(
u,s)
|
0 1 2 3 4 5 6
-1
-0.5
0
0.5
1
1.5
log2(s)lo
g2(|W
f(u,
s)|)
+1/2=1/2
sAsuWf 222 log2
1log,log
![Page 19: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/19.jpg)
![Page 20: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/20.jpg)
CWT modulus maxima line
SyntheticReflectivity CWT Magnitude
CWTmagnitude
0
pos
CWT MML
![Page 21: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/21.jpg)
WTMMLA seismic applications
![Page 22: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/22.jpg)
ICWT “deconvolution” workflow
SyntheticReflectivity CWT Magnitude
CWTmagnitude
0
pos
CWT MML
CWTMorlet
CWT MML
ICWTShrunken
Morlet
CWT MML voices
Σ
![Page 23: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/23.jpg)
Relative acoustic impedance from ICWTDEC
WORKFLOW
- Re-scale seismic trace: |s(t)|<<1- Integration filter (Peacock, 1979) - High-pass filter
![Page 24: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/24.jpg)
Summary
Introduction
Continuous Wavelet Transform (very brief review)
ICWTdec
Examples
Conclusions
24
![Page 25: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/25.jpg)
Case 1: Synthetic seismic channel
10 ms thickness trace
![Page 26: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/26.jpg)
Case 1: Synthetic seismic channel
30 ms thickness trace
![Page 27: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/27.jpg)
Synthetic channel and its ICWTdec
ICWTDEC RAI
![Page 28: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/28.jpg)
Adding random noise
![Page 29: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/29.jpg)
Case 2: Barnet Shale
Original Seismic
![Page 30: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/30.jpg)
ICWTdec
![Page 31: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/31.jpg)
THINMAN™
![Page 32: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/32.jpg)
Marble Falls
Upper Barnett Lm
Upper Barnett Sh
Forestburg
Lower Barnett Sh
Viola
ICWTdec
60Amplitude
60
0
![Page 33: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/33.jpg)
Marble Falls
Upper Barnett Lm
Upper Barnett Sh
Forestburg
Lower Barnett Sh
Viola
THINMAN™
10Amplitude
10
0
![Page 34: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/34.jpg)
Case 3: Pre-stack (Hampson&Russel 2D demo data set)
Twt (s)
0
0.7
Offset
![Page 35: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/35.jpg)
ICWTdec
Twt (s)
0
0.7
Offset
![Page 36: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/36.jpg)
RAI
Twt (s)
0
0.7
Offset
![Page 37: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/37.jpg)
Spectral ridges Conclusions
• CWT spectral decomposition filtering process described dear generates high resolution events that correlate to major acoustic impedance changes.
• Since this broadening is a trace-by-trace independent process, laterally-consistent thin bed terminations and other truncations can be interpreted with confidence.
![Page 38: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/38.jpg)
Q estimation
• Anelasticity and wave propagation “very brief” review• Q estimation and spectral ridges• Conclusions
![Page 39: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/39.jpg)
Anelasticity
Berea Sandstone
Wyllie, et al, 1958
From Carl Sondergeld Rock Physics Course Notes, 2009
![Page 40: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/40.jpg)
Anelasticity review
From Carl Sondergeld Rock Physics Course Notes, 2009
![Page 41: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/41.jpg)
Wave equation
From Carl Sondergeld Rock Physics Course Notes, 2009
![Page 42: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/42.jpg)
Attenuation per wavelength
From Carl Sondergeld Rock Physics Course Notes, 2009
![Page 43: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/43.jpg)
Normal incidence anelastic reflections
From Carl Sondergeld Rock Physics Course Notes, 2009
![Page 44: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/44.jpg)
Seismic wave behavior in absorptive media defined by v, ρ and Q.
Figure 2.4 of Seismic Absorption Estimation and Compensation by Changjun Zhang M.Sc., The University of British Columbia, 2009
• Q is inversely proportional to attenuation. The greater the Q value, the smaller the loss or attenuation!
• The phase lag Ψ is a direct measure of attenuation. The greater the phase lag, the greater the attenuation.
• Q for rock lies in the range of 10 to 200.• If Q = Q(ω) then M must also be a function of frequency!• Moduli must depend upon frequency!
![Page 45: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/45.jpg)
Q estimation
• Anelasticity and wave propagation “very brief” review• Q estimation and spectral ridges• Conclusions
![Page 46: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/46.jpg)
Q estimation from spectral ratio
freqAdrinal Ilyas, 2010, Estimation of q factor from seismic reflection data, MsC Curtin University
Chopra, Alexeev, and Sudhakar, TLE 2003, High-frequency restoration of surface seismic data
![Page 47: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/47.jpg)
Q estimation from spectral ratio
• Synthetic
• Reflectivity
• CWT Magnitude
• CWT• magnitude
• 0
• pos
• CWT MML
Spectral ridges can guide Q estimation from spectral ratio
In Q computation, we need to compute the amplitude spectra of two adjacent events (Taner, 2000)
![Page 48: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/48.jpg)
Q estimation from Peak Frequency variation
Ricker wavelet
Zhang & Ulrych, 2002, Geophysics, Estimation of Quality factors from CMP records
![Page 49: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/49.jpg)
Q estimation from Peak Frequency variation
Zhang & Ulrych, 2002, Geophysics, Estimation of Quality factors from CMP records
![Page 50: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/50.jpg)
Q estimation from Peak Frequency variation
Zhang_Ulrych_2007_Geophysics_Seismic absorption compensation A least squares inverse scheme
![Page 51: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/51.jpg)
Frequency decay caused by thin-bed tuning and absorption
Figure 4.2 of Seismic Absorption Estimation and Compensation by Changjun Zhang M.Sc., The University of British Columbia, 2009
![Page 52: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/52.jpg)
Absorption and specdecomp phase components
SyntheticReflectivity CWT Magnitude
CWTmagnitude
0
pos
CWT MML
180
-180
CWT phase
10 70
Frequency (Hz)
![Page 53: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/53.jpg)
CWT Magnitude and Phase overlaid by spectral ridgesThe phase spectra will provide information for dispersion estimation. Attributes picked at the peak of the envelope represent the average of the wavelet attribute. That is why we pick the amplitude spectrum at the time of envelop peak for Q computation. Phase spectra is picked the same way. If we look at the phase spectra, we observe that most of the spectra of the events are horizontal, which means that these wavelets are zero phase, and their rotation angle is the phase corresponding to the envelop peak. Therefore, computation of dispersion consists of determining the phase differences at each sub-band trace and compute an average phase delay per cycle per second. Since dispersion is related to absorption, higher levels of dispersion will point to higher levels of absorption, which may indicate fracture in carbonates or unconsolidated snads in clastic environment. (Taner, 2000).
![Page 54: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/54.jpg)
Conclusions
• CWT spectral decomposition filtering process described dear generates high resolution events that correlate to major acoustic impedance changes.
• It seems we can correlate spectral ridges with Q estimation
![Page 55: SISMO Can we use the spectral ridges to estimate Q ? Marcílio Castro de Matos marcilio@matos.eng.brmarcilio@matos.eng.br .](https://reader030.fdocuments.us/reader030/viewer/2022032805/56649eea5503460f94bfbdcf/html5/thumbnails/55.jpg)
Acknowledgements
Attribute-Assisted Seismic Processing and Interpretation
http://geology.ou.edu/aaspi/
[email protected] www.matos.eng.br
Thank you for your attention!!!
Thanks to DEVON for providing a license to one of the seismic data volume used herein.
Thanks to Carl Sondergeld
Thanks to Roderick Perez from OU for his Barnet shale interpretation.
Thanks also to PETROBRAS Reservoir Geophysics Management friends for their comments.
Signal Processing Research, Training & Consultingwww.sismo.srv.br