Specular Interferometric Migration of Specular Interferometric Migration of Free Surface Multiples in Free Surface Multiples in
VSP Land DataVSP Land Data
C. Boonyasiriwat and M. ZhouC. Boonyasiriwat and M. Zhou
Dept. of Geology & GeophysicsDept. of Geology & GeophysicsUniversity of UtahUniversity of Utah
OutlineOutline
• Numerical ResultsNumerical Results
• ConclusionConclusion
• Specular Interferometric MigrationSpecular Interferometric Migration
• Data ProcessingData Processing
• ProblemProblem
ProblemProblem
• Specular interferometric migration is cheaperSpecular interferometric migration is cheaper
• Land data have problems with the Land data have problems with the weathering zonesweathering zones
• Interferometric migration is expensiveInterferometric migration is expensive
• Marine data have very strong multiplesMarine data have very strong multiples
OutlineOutline
• Numerical ResultsNumerical Results
• ConclusionConclusion
• Specular Interferometric MigrationSpecular Interferometric Migration
• Data ProcessingData Processing
• ProblemProblem
Specular Interferometric MigrationSpecular Interferometric Migration
s s’ s*
g
x
Specular reflection
gsxssx ''~
Diffraction time
gsxssx **~
Specular time
Specular Interferometric Migration Specular Interferometric Migration of first-order multiplesof first-order multiples
)(*
,
1 **)|()|()|()( gsxssxi
gs
egsdgsGgsdxm
)|()|()|()|( ******1 gsGsxGxsGgsG
Migration Equation:
Natural Green’s Function
Natural Time
Calculated Time
Model-based Green’s Function
Specular Interferometric Migration Specular Interferometric Migration vsvs
Interferometric MigrationInterferometric Migration
s g
sxGxsGgsGgsdxm )|()|()|()|()( *****
Specular Interferometric Migration:
x
s
g
s*
Specular Interferometric Migration Specular Interferometric Migration vsvs
Interferometric MigrationInterferometric Migration
',
*** )'|()|()|'()|()(ss g
sxGxsGgsdgsdxm
Interferometric Migration:
x
s
g
s’
Specular Interferometric Migration Specular Interferometric Migration vsvs
Interferometric MigrationInterferometric Migration
s g
sxGxsGgsGgsdxm )|()|()|()|()( *****
Specular Interferometric Migration:
',
*** )'|()|()|'()|()(ss g
sxGxsGgsdgsdxm
Interferometric Migration:
OutlineOutline
• Numerical ResultsNumerical Results
• ConclusionConclusion
• Specular Interferometric MigrationSpecular Interferometric Migration
• Data ProcessingData Processing
Processing Steps for Primary ReflectionsProcessing Steps for Primary Reflections
Raw Data
AGC
Normalization
Separate Upgoing Wave
Kirchhoff Migration withResidual Statics Corrections
Processing Steps for Ghost ReflectionsProcessing Steps for Ghost Reflections
Raw Data
Normalization
AGC
Separate Downgoing Wave
Specular Interferometric Migration withResidual Statics Corrections
OutlineOutline
• Numerical ResultsNumerical Results
• ConclusionConclusion
• Specular Interferometric MigrationSpecular Interferometric Migration
• Data ProcessingData Processing
Forward Modeling ResultsForward Modeling Results
S-wave ghosts
P-wave ghost0
3.5
Tim
e (s
)
-4 4Offset (km) -4 4Offset (km)
Primaries from Acous. Wave Eq.Primaries + Ghosts from Elastic
Wave Eq.
s
g
x
Comparison between Field and Synthetic ResultsComparison between Field and Synthetic Results
S-wave ghosts
P-wave ghost
-4 4Offset (km)-4 4Offset (km)
0
3.5
Tim
e (s
)
Field Data Synthetic Data
Residual Statics CorrectionResidual Statics Correction
-4 4Offset (km)-4 4Offset (km)
0.2
2
Tim
e (s
)
Before statics correction After statics correction
-2 2Offset (km)
0
5
Dep
th (
km)
Kirchhoff Migration of Primaries
-2 2Offset (km)
0
5
Dep
th (
km)
Specular Interferometric Migration of Ghosts
Primary migration result overlaid on the surface data
Ghost migration result overlaid on the surface data
OutlineOutline
• Numerical ResultsNumerical Results
• ConclusionConclusion
• Specular Interferometric MigrationSpecular Interferometric Migration
• Data ProcessingData Processing
ConclusionsConclusions
• Both Kirchhoff and specular interferometric images correlate well with Both Kirchhoff and specular interferometric images correlate well with the CDP image.the CDP image.
• Migration image of primaries has a better S/N ratio for the P-wave image Migration image of primaries has a better S/N ratio for the P-wave image zone.zone.
• VSP land data contain strong primaries compared to P- and S-wave VSP land data contain strong primaries compared to P- and S-wave multiples.multiples.
• Migration image of ghosts has a wider subsurface coverage and flatter Migration image of ghosts has a wider subsurface coverage and flatter layers.layers.
• Specular interferometric migration gives comparable results to the Kirchhoff Specular interferometric migration gives comparable results to the Kirchhoff migration.migration.
