Imaging of complex structures by 3-D reflection seismic data
Biondo Biondi
Stanford Exploration ProjectStanford University
IPRPI Workshop on Geophysical Imaging
1) 2-D ADCIG 2) 3-D ADCIG
2An example of imaging complex structures…
1) Potentials of wavefield-continuation methods can be fulfilled only if we use MVA methods based on:
Wavefield-continuation migration
• Salt-boundary picking
• Below salt Common Image Gathers (CIG)
Wavefield-continuation velocity updating
2) We may need to go beyond downward-continuation migration methods and …
be able to perform MVA
5Outline
• Migration and complex wave propagation
• Wavefield continuation migration
• Gaussian Beams and Coherent States migration
• Migration => Iterative Regularized Inversion
• Normalized Migration
• Iterative Wavefield Inversion with geophysical and geological constraints
• Migration Velocity Analysis (MVA)
• Angle Domain Common Image Gathers (ADCIGs)
• Ray tomography using ADCIGs
• Wave-equation Migration Velocity Analysis
• Routine
• Advanced
• Future?
6Outline
• Migration and complex wave propagation
• Wavefield continuation migration
• Gaussian Beams and Coherent States migration
• Migration => Iterative Regularized Inversion
• Normalized Migration
• Iterative Wavefield Inversion with geophysical and geological constraints
• Migration Velocity Analysis (MVA)
• Angle Domain Common Image Gathers (ADCIGs)
• Ray tomography using ADCIGs
• Wave-equation Migration Velocity Analysis
• Routine
• Advanced
• Future?
15Outline
• Migration and complex wave propagation
• Wavefield continuation migration
• Gaussian Beams and Coherent States migration
• Migration => Iterative Regularized Inversion
• Normalized Migration
• Iterative Wavefield Inversion with geophysical and geological constraints
• Migration Velocity Analysis (MVA)
• Angle Domain Common Image Gathers (ADCIGs)
• Ray tomography using ADCIGs
• Wave-equation Migration Velocity Analysis
• Routine
• Advanced
• Future?
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Superposition of Beamss
p0sp’0s
x’
x
Solve wave equation by localizing initial wavefield in space and ray parameter (wavenumber)
Extrapolate and superimpose these solutions to form
wavefield
If local solution is accurate and superpositionis correct, accurate wavefield should result,
including all arrivals, amplitudes, and phases
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Gaussian Beam (Ray based)s
Cerveny, Popov, Psencik 1982Hill, 1990, 2001Kinneging et al 1989White et al 1987Hale 1992
p0s
x
p0sp’0s
x’
x
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Asymptotic Coherent State (Ray based)s
Foster and Huang, 1991Thompson, 2000Albertin et al 2001
p0s
x
p0sp’0s
x’
x
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Wavefield-Extrapolated Coherent Statep0s
Foster and Huang 1991Wu et al 2000Albertin 2001
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Wavefield Extrapolated Zero-offset Impulse
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Asymptotic Coherent State Reconstruction
3 raytraced coherent states
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Asymptotic Coherent State Reconstruction
12 raytraced coherent states
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Asymptotic Coherent State Superposition
572 raytraced coherent states
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Wavefield Extrapolated Zero-offset Impulse
26SEG/EAGE salt data set - CrosslineWavefield-continuation migration
Kirchhoff migration
© 2001Jun 17, 2001
Schlumberger Private
Uwe Albertin, WesternGeco
Beam Migration y=375
28Outline
• Migration and complex wave propagation
• Wavefield continuation migration
• Gaussian Beams and Coherent States migration
• Migration => Iterative Regularized Inversion
• Normalized Migration
• Iterative Wavefield Inversion with geophysical and geological constraints
• Migration Velocity Analysis (MVA)
• Angle Domain Common Image Gathers (ADCIGs)
• Ray tomography using ADCIGs
• Wave-equation Migration Velocity Analysis
• Routine
• Advanced
• Future?
29Offset Domain CIG (Kirchhoff)
Off1
Off2
Off3
ReceiversSources
Depth
Off1 Off2 Off3
Vmig = Vtrue
30Angle Domain CIG (wavefield continuation)
ReceiversSources
Depth
γ1γ1
γ2γ3
γ2 γ3
αVmig = Vtrue
40Outline
• Migration and complex wave propagation
• Wavefield continuation migration
• Gaussian Beams and Coherent States migration
• Migration => Iterative Regularized Inversion
• Normalized Migration
• Iterative Wavefield Inversion with geophysical and geological constraints
• Migration Velocity Analysis (MVA)
• Angle Domain Common Image Gathers (ADCIGs)
• Ray tomography using ADCIGs
• Wave-equation Migration Velocity Analysis
• Routine
• Advanced
• Future?
41Migration => Normalized Migration
Migration dm *L=
Least-Squares Migration ( ) dm *1* LLL −=
Normalized Migration dm *1LW −=
43Migration => Iterative Regularized Inversion
Least-Squares Migration ( ) dm *1* LLL −=
Iterative Regularized Inversion
( ) dm *1*2* ε LAALL −+=
44Regularization operator (A)
z
xph
z
Geophysical regularization Geological regularization
48Inversion with Geophysical regularizationMigration Normalized
MigrationRegularizedInversion
Courtesy of Marie Clapp (SEP)
49Outline
• Migration and complex wave propagation
• Wavefield continuation migration
• Gaussian Beams and Coherent States migration
• Migration => Iterative Regularized Inversion
• Normalized Migration
• Iterative Wavefield Inversion with geophysical and geological constraints
• Migration Velocity Analysis (MVA)
• Angle Domain Common Image Gathers (ADCIGs)
• Ray tomography using ADCIGs
• Wave-equation Migration Velocity Analysis
• Routine
• Advanced
• Future?
50ADCIGs with correct velocity
ReceiversSources
Depth
γ1γ1
γ2γ3
γ2 γ3
αVmig = Vtrue
51ADCIGs and velocity errors
ReceiversSources
Depth
γ1
Vmig < Vtrue
γ1γ2
γ3
γ2 γ3
α
Vmig < Vtrue ∆l1 < ∆l2 < ∆l3
∆l2∆l1 ∆l3
52ADCIGs and local velocity errors
ReceiversSources
γ1γ1
γ2γ3
γ2 γ3
Vmig < Vtrue
αVmig < Vtrue
Depth
57Outline
• Migration and complex wave propagation
• Wavefield continuation migration
• Gaussian Beams and Coherent States migration
• Migration => Iterative Regularized Inversion
• Normalized Migration
• Iterative Wavefield Inversion with geophysical and geological constraints
• Migration Velocity Analysis (MVA)
• Angle Domain Common Image Gathers (ADCIGs)
• Ray tomography using ADCIGs
• Wave-equation Migration Velocity Analysis
• Routine
• Advanced
• Future?
58Outline
• Migration and complex wave propagation
• Wavefield continuation migration
• Gaussian Beams and Coherent States migration
• Migration => Iterative Regularized Inversion
• Normalized Migration
• Iterative Wavefield Inversion with geophysical and geological constraints
• Migration Velocity Analysis (MVA)
• Angle Domain Common Image Gathers (ADCIGs)
• Ray tomography using ADCIGs
• Wave-equation Migration Velocity Analysis
• Routine
• Advanced
• Future?
59Migration Migration Velocity Analysis
wavefronts wavefields
Kirchhoff migration
traveltime tomography
Wave-equation migration
Wave-equation MVA
Courtesy of Paul Sava (SEP)
60A tomography problem
sqs ∆− L∆min∆Traveltime
MVAWave-equation
tomographyWave-equation MVA
∆q ∆ttraveltime
∆ddata
wavefield
∆Rimage
L ray field wavefield
Courtesy of Paul Sava (SEP)
61WEMVA: main idea
0WWW∆ −=
∆ss0+
( ) ( )sii ∆∆+= ϕϕ 0seW U
0s
( )0s0 eW ϕiU=
Courtesy of Paul Sava (SEP)
62WEMVA: objective function
slownessperturbation
slownessperturbation(unknown)
Linear WEMVAoperator
imageperturbation
(known)
sRs ∆− L∆∆min
image perturbation
Courtesy of Paul Sava (SEP)
82Conclusions
• Complex structures require accurate and expensive wavefield-continuation imaging operators.
• To image reflectors that are poorly illuminated we need to go beyond the application of the adjoint operator (migration) and move towards “intelligent” (regularized) inversion.
• Wavefield-continuation operators are beneficial not only for migration but also for velocity estimation.
• The estimation of holes in poorly illuminated reflectors and of velocity errors are tightly coupled problems.
83Acknowledgments
Uwe Albertin at WesterGeco for Gaussian Beam slides.
SMAART JV and J. Paffenholz (BHP) for the Sigsbeedata set.
Unocal and Phil Schultz for Deep Water GOM data.
3DGeo for images of Deep Water GOM data.
Total for North Sea data set.
SEP sponsors for financial support.