2015 workplan for “vvaz” analysis of prestack migrated data jie qi and kurt j. marfurt (the...
TRANSCRIPT
![Page 1: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/1.jpg)
2015 Workplan for “VVAz” Analysis of Prestack Migrated Data
Jie Qi and Kurt J. Marfurt
(The University of Oklahoma)
AASPI
![Page 2: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/2.jpg)
Outline
• Introduction• Motivation• Challenge
• Methodology • VVAz • AVAz• Azimuthal crosscorrelation
• Application• Geology background• Azimuthal attributes
• Conclusion
2
AASPI
![Page 3: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/3.jpg)
Motivation
• Azimuthally limited or vector-tile gathers are part of the wide-azimuth processing workflow
• Can we implement interpretation tools to provide residual AVAz analysis capabilities?
• If the data were migrated using isotropic velocities, these residuals are a measure of VVAz
• The application of such a tool would increase vertical resolution and precondition the data for subsequent AVAz analysis
3
![Page 4: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/4.jpg)
4
Horizontal Transverse Isotropy (HTI) medium
(Left): No HTI anisotropy results in equal travel time paths in all azimuths;
(Right): In an HTI anisotropic media with aligned vertical fractures the travel time is azimuth dependent and is not equal in all directions.
(Courtesy of Close et. al., 2010)
![Page 5: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/5.jpg)
Shear wave spitting in anisotropic medium
5(Courtesy of Ed Garnero)
3-CReceiver
![Page 6: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/6.jpg)
Fracture:
• A key factor in the optimization of reservoir production
• High natural fractures – high production
• Helps to identify sweet spots
• Anisotropic properties: intensity and orientation
• Anisotropy analysis: amplitude and velocity
6(Photos courtesy of Brian Cardott)
Woodford shale Marcellus Shale
![Page 7: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/7.jpg)
Outline
• Introduction• Motivation• Challenge
• Methodology • VVAz • AVAz• Azimuthal crosscorrelation
• Application• Geology background• Azimuthal attributes
• Conclusion
7
AASPI
![Page 8: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/8.jpg)
Velocity vs. Azimuth (VVAz)
• Advantages • Easy to generate azimuthally-binned data• Computation is fast and simple, providing a level of confidence• Requires phase- but not amplitude-preservation
• Disadvantages• Suffers from vertical resolution problems associated with Dix’s equation
8
Amplitude vs. Azimuth (AVAz)
• Advantages • Easy to generate azimuthally-binned data• Computation is fast and simple, providing a level of confidence • Computations are volumetric within the (properly registered) zone of interest
• Disadvantages• Requires amplitude-preserving processing and migration (AVAz)
![Page 9: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/9.jpg)
Velocity variation with angle and azimuth (VVAZ)
9
Vint(φ)=V0+εcos[2(φ- φsym)]
θ
Nφ
Nφsym
If ε is zero, it becomes interval velocity.
φsym
![Page 10: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/10.jpg)
Amplitude vs. Azimuth (AVAz)
(Rueger, 1996)
R(θ,φ)=A+{Biso+Banisocos[2(φ- φsym)]}sin2θ
θ
Nφ
Nφsym
Amplitude vs. Offset (AVO)R(θ,φ)=A+{Biso }sin2θ
Amplitude vs. Azimuth (AVAz)R(θ,φ)=A+{Biso+Banisocos[2(φ- φsym)]}sin2θ
Amplitude vs. Offset (AVO)R(θ,φ)=A+{Biso }sin2θ
10
![Page 11: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/11.jpg)
Workflows
Conventional VVAz:• Generate long-offset sectors or ’tiles’ at different azimuths φ (unmigrated)• At discrete picked horizons, compute VRMS as a function of azimuth, φ
• Compute interval velocities Vint(φ) using Dix’s equation
• Fit a sinusoidal curve to Vint(φ) to obtain the magnitude and azimuth of anisotropy
AVAz:• Generate long-offset sectors or ’tiles’ at different azimuths φ (migrated)• Pick discrete upper and lower horizons and generate either flattened or stratal
slices throughout the volumetric zone of interest• At every time or depth sample, fit a sinusoid to the amplitude as a function of
azimuth φ
11
![Page 12: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/12.jpg)
12
Residual “VVAz” Workflow
Shot gathers
PrestackTime
migration
Azim 1 gathers
Azim 8 gathers
……Azim 2 gathers
AVAz anisotropyBaniso, ψaniso
Migrated gathers
Dynamic alignment
VVAz Anisotropy
Structure oriented filter
Dynamic alignment
![Page 13: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/13.jpg)
Dynamic alignment• Correlate adjacent azimuths
• Find ∆τ and value of highest correlation coefficient• Autocorrelate & crosscorrelate
13
……
Azim 1 Azim 2 Azim 8Time
![Page 14: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/14.jpg)
(Modified from Roende et al., 2008) 14
Vint(φ)=V0+εcos[2(φ- φsym)]
Azimuth, φ
V 0+εc
os[2
(φ- φ
sym
)]
ε iso
ε anisoφsy
m
V0
V0 + ε
V0 - ε
Dynamic alignment
• Least-squares fit ∆τ to find εaniso and φsym
![Page 15: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/15.jpg)
15
Isotropic Layer 1
Anisotropic Layer 2
Dynamic alignment
Dynamicalignment
Isotropic Layer 1
Anisotropic Layer 2
High anisotropy
Azimuthal data
Aligned data
• Stretch and squeeze data to provide flattened events
εaniso and φsym
Isotropic Layer 1
Anisotropic Layer 2
![Page 16: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/16.jpg)
Outline
• Introduction• Motivation• Challenge
• Methodology • VVAz • AVAz• Azimuthal crosscorrelation
• Application• Geology background• Azimuthal attributes
• Conclusion
16
AASPI
![Page 17: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/17.jpg)
Ellenburger
Marble Falls
Stratigraphic Cross Section
(Modified from Pollastro et al., 2009)
Unconformity
17
![Page 18: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/18.jpg)
Stacked azimuth sector gathersAnisotropy indicators
Data aligned Data Misaligned(Roende et al., 2008)
CMP398
CMP399
CMP400
Tim
e (s
)
0.8
0.7
0.6
0.5
CMP no.
18
![Page 19: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/19.jpg)
Amplitude as a function of azimuth (AVAz)
~3500 ft
0.6
0.8
~8 ms
Tim
e (s
)
0.7
stro
nge
r
weake
r
(Roende et al., 2008) 19
![Page 20: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/20.jpg)
AVAz products
Low High 1 mile
Tim
e (s
)
0.4
1.0 Intercept, A
Isotropic gradient, Biso
Tim
e (s
)
0.4
1.0
Anisotropic gradient, Baniso
Tim
e (s
)
0.4
1.0
(Modified from Roende et al., 2008) 20
Top Marble Fall
Top Ellenburger
![Page 21: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/21.jpg)
Outline
• Introduction• Motivation• Challenge
• Methodology • VVAz • AVAz• Azimuthal crosscorrelation
• Conclusion
21
AASPI
![Page 22: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/22.jpg)
Anticipated Challenges
• Will there be a clear correlation between AVAz and VVAz?
• Can the residuals be computed gather by gather, or will layer-stripping become important?
22
![Page 23: 2015 Workplan for “VVAz” Analysis of Prestack Migrated Data Jie Qi and Kurt J. Marfurt (The University of Oklahoma) AASPI](https://reader035.vdocument.in/reader035/viewer/2022062516/56649e365503460f94b25fce/html5/thumbnails/23.jpg)
Acknowledgements
• Marathon Oil Co. for a license to their survey
• Sponsors of the AASPI consortium for financial support and
technical encouragement
23
AASPI