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Wave-Equation Wave-Equation Interferometric Migration Interferometric Migration
of VSP Dataof VSP Data
Ruiqing HeRuiqing He
Dept. of Geology & Dept. of Geology & GeophysicsGeophysics
University of UtahUniversity of Utah
OutlineOutline
• AcknowledgementsAcknowledgements
• Introduction of Seismic InterferometryIntroduction of Seismic Interferometry
• Wave-equation Interferometric MigrationWave-equation Interferometric Migration– 3D Migration of VSP Multiples3D Migration of VSP Multiples– Salt Flank ImagingSalt Flank Imaging
• Conclusion & Technical ContributionsConclusion & Technical Contributions
OutlineOutline
• AcknowledgementsAcknowledgements
• Introduction of Seismic InterferometryIntroduction of Seismic Interferometry
• Wave-equation Interferometric MigrationWave-equation Interferometric Migration– 3D Migration of VSP Multiples3D Migration of VSP Multiples– Salt Flank ImagingSalt Flank Imaging
• Conclusion & Technical ContributionsConclusion & Technical Contributions
AcknowledgementsAcknowledgements
• Thank Jerry Schuster for enlightening Thank Jerry Schuster for enlightening lectures, innovating discussions, lectures, innovating discussions, supervising and support.supervising and support.
• Thank Bob Smith, Cari Johnson, Kris Thank Bob Smith, Cari Johnson, Kris Sikorski for teaching and Sikorski for teaching and supervising. Thank Yue Wang for supervising. Thank Yue Wang for supervising.supervising.
• Thank my family.Thank my family.
OutlineOutline
• AcknowledgementsAcknowledgements
• Introduction of Seismic InterferometryIntroduction of Seismic Interferometry
• Wave-equation Interferometric MigrationWave-equation Interferometric Migration– 3D Migration of VSP Multiples3D Migration of VSP Multiples– Salt Flank ImagingSalt Flank Imaging
• Conclusion & Technical ContributionsConclusion & Technical Contributions
Introduction of Introduction of Seismic InterfeometrySeismic Interfeometry
• Passive Seismic Imaging:Passive Seismic Imaging:– Claerbout (1968)Claerbout (1968)– Katz (1990); Cole (1995)Katz (1990); Cole (1995)– Daneshvar et al. (1995)Daneshvar et al. (1995)
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
• Daylight Imaging:Daylight Imaging:– Rickett & Claerbout (1996, 1999, 2000)Rickett & Claerbout (1996, 1999, 2000)– Helioseismologists (Duvall et al., 1993)Helioseismologists (Duvall et al., 1993)– Schuster (1999,2000), Wapenaar (2003)Schuster (1999,2000), Wapenaar (2003)
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
• Virtual Source:Virtual Source:– Calvert, Bakulin, et al. (2004)Calvert, Bakulin, et al. (2004)
Overburden
Target
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
• Seismic Interferometry:Seismic Interferometry:– Schuster & Rickett (1999)Schuster & Rickett (1999)– Schuster (2001)Schuster (2001)– Yu & Schuster (2001, 2006)Yu & Schuster (2001, 2006)– Jiang et al. (2005)Jiang et al. (2005)
• No restriction on source distribution
• Arbitrary velocity model
• Many types of events used
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
• Seismic Interferometry Theory:Seismic Interferometry Theory:
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
• Migration of VSP Multiples:Migration of VSP Multiples:
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
• Successful Applications:Successful Applications:
Xiao, et al. (2005)
UTAM report
Drilling …
3D
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
• Robust Imaging:Robust Imaging:Kirchhoff Migration
Interferometric Migration
KM
IM
Overburden
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
• Super Resolution:Super Resolution:
Kirchhoff Migration Interferometric Migration
VSP salt flank imaging
HSP imaging
VSP multiple migration
CDP multiple migration
Salt Dome
Introduction of Introduction of Seismic Interfeometry Seismic Interfeometry (continued)(continued)
Various applications:
overburden
OutlineOutline
• AcknowledgementsAcknowledgements
• Introduction of Seismic InterferometryIntroduction of Seismic Interferometry
• Wave-equation Interferometric MigrationWave-equation Interferometric Migration– 3D Migration of VSP Multiples3D Migration of VSP Multiples– Salt Flank ImagingSalt Flank Imaging
• Conclusion & Technical ContributionsConclusion & Technical Contributions
Wave-Equation Interferometric Wave-Equation Interferometric Migration (WEIM): Migration (WEIM): considerationconsideration
Kirchhoff Migration Costs:1) Crosscorrelation2) Ray tracing3) Storage for traveltime tables
For Example: To obtain 85 x 87 x 1400
migrationcube, ~300 GB disk is required.
IVSP
WEIM: WEIM: theorytheory
WEIM costs for one gather:1) One wavefield
extrapolation2) One ray tracing3) One traveltime table
IVSP
Line-source Ray TracingLine-source Ray Tracing
Knownmedium
Unknown medium
The picked time is imposed as an initial condition in ray tracing.
It is as efficient as conventional point-source ray tracing.
3D WEIM of VSP Multiples3D WEIM of VSP Multiples
2D Synthetic Test2D Synthetic Test
Offset (m)0 6000
Dep
th (
m)
0
4000
Offset (m)0 6000
Tim
e (s
)
0
5
Synthetic model Synthetic data
12 geophpnes
600 shots
Multiples
Migration ComparisonMigration Comparison
Offset (m)0 6000
Dep
th (
m)
0
4000
Migration of primaries Migration of multiples
Offset (m)0 6000
Dep
th (
m)
0
4000
Field Data ApplicationField Data Application
Survey GeometrySurvey Geometry
Each geophone grouphas 12 geophones.
~ 11 km
~ 11 km
~ 5 km deep
3 similar spirals,each correspondingto an offset-edgeophone group.
3D WEIM Result3D WEIM ResultMigration of only one receiver gather
Slice MovieSlice MovieMigration of only one receiver gather
Slice of 3D Migration CubeSlice of 3D Migration Cube
Offset (m)0 11000
Dep
th (
m)
0
6500
Common Image GatherCommon Image Gather
Offset (m)1 36
Dep
th (
m)
0
6500
VSP Salt Flank ImagingVSP Salt Flank Imaging
? 98 geophones
120 shots
Overburden
Interferometric Migration Interferometric Migration ResultResult
A Synthetic ExperimentA Synthetic Experiment
94 geophones
10 shots
Overburden
A Shot GatherA Shot Gather
WEIM Result (one shot)WEIM Result (one shot)
Offset (m)
0 1700
Dep
th (
m)
2700
5500
Artifacts
WEIM Result (ten shots)WEIM Result (ten shots)
Offset (m)
0 1700
Dep
th (
m)
2700
5500
OutlineOutline
• AcknowledgementsAcknowledgements
• Introduction of Seismic InterferometryIntroduction of Seismic Interferometry
• Wave-equation Interferometric MigrationWave-equation Interferometric Migration– 3D Migration of VSP Multiples3D Migration of VSP Multiples– Salt Flank ImagingSalt Flank Imaging
• Conclusion & Technical ContributionsConclusion & Technical Contributions
ConclusionConclusion
• Seismic interferometry is a robust Seismic interferometry is a robust imaging tool, and has a variety of imaging tool, and has a variety of applications. applications.
• However, the relatively weak energy However, the relatively weak energy waves and low fold imaging in some waves and low fold imaging in some applications could result in the low applications could result in the low S/N ratio of the image.S/N ratio of the image.
Technical Contributions (I)Technical Contributions (I)
• Wave-equation interferometric migration Wave-equation interferometric migration is proposed for efficient 3D migration of is proposed for efficient 3D migration of VSP multiples.VSP multiples.– It is as robust to velocity estimation errors as It is as robust to velocity estimation errors as
surface seismic imaging.surface seismic imaging.– It is much more cost efficient than surface It is much more cost efficient than surface
seismic surveys in obtaining a 3D subsurface seismic surveys in obtaining a 3D subsurface image volume.image volume.
– It might be also useful for time-lapse (4D) It might be also useful for time-lapse (4D) seismic monitoring for some oil fields.seismic monitoring for some oil fields.
Technical Contributions (II)Technical Contributions (II)
• Apply interferometric migration to Apply interferometric migration to salt flank imaging with VSP data:salt flank imaging with VSP data:– A huge chunk of overburden is ignored, A huge chunk of overburden is ignored,
so that the imaging is not only efficient, so that the imaging is not only efficient, but also robust to velocity estimation but also robust to velocity estimation errors.errors.
– Other vertical structures, such as faults Other vertical structures, such as faults that are difficult to image by surface that are difficult to image by surface seismic surveys could also be imaged.seismic surveys could also be imaged.
The EndThe End
Thank you.Thank you.
Ray DistributionRay Distribution
CDP ray distribution VSP ray distribution
Migrating Missed Near-offset Migrating Missed Near-offset TracesTraces
Missed near-offset traces due to limited acquisition.
Some of the missed near-offset traces can be migrated in the migration of multiples.
Synthetic TestSynthetic Test
Offset (m)0 5000
Depth (m)
0
1500
300 m20 m 20 m
Migration of PrimariesMigration of Primaries
Offset (m)0 5000
Depth (m)
0
1500
Migration of MultiplesMigration of Multiples
Offset (m)0 5000
Depth (m)
0
1500
Migration of Field Data Migration of Field Data PrimariesPrimaries
Offset (m)0 26000
Depth (m)
0
3500
Shortest offset=262 m; Shot and geophone spacing=25 m
Migration of Field Data Migration of Field Data MultiplesMultiples
Offset (m)0 26000
Depth (m)
0
3500
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