crosswell imaging by 2-d prestack wavepath migration
DESCRIPTION
CROSSWELL IMAGING BY 2-D PRESTACK WAVEPATH MIGRATION. H. Sun. Geology and Geophysics Department University of Utah. SEG 2-D Overthrust Data. KM Image. Model. WM Image. 4. Offset (km). 10. 4. Offset (km). 10. 4. Offset (km). 10. 0.5. Depth (km). 2.5. - PowerPoint PPT PresentationTRANSCRIPT
CROSSWELL IMAGING BY 2-D CROSSWELL IMAGING BY 2-D PRESTACK WAVEPATH PRESTACK WAVEPATH
MIGRATIONMIGRATION
H. SunH. Sun
Geology and Geophysics Department Geology and Geophysics Department University of UtahUniversity of Utah
Offset (km)Offset (km)44 1010
De
pth
(k
m)
De
pth
(k
m)
0.50.5
2.52.5
44 Offset (km)Offset (km) 1010 44 Offset (km)Offset (km) 1010
KM ImageKM Image WM ImageWM ImageModelModel
SEG 2-D Overthrust DataSEG 2-D Overthrust Data
2-D Husky Field Data2-D Husky Field Data
Offset (km)Offset (km)2.52.5 5.55.5
2.52.5
5.05.0
De
pth
(k
m)
De
pth
(k
m)
KM Image (Zoom A)KM Image (Zoom A) WM Image (Zoom A)WM Image (Zoom A)
Offset (km)Offset (km)2.52.5 5.55.5
2.52.5
De
pth
(k
m)
De
pth
(k
m)
5.05.0
WMWM
ModelModel
KM KM
SubSubWMWM
SEG 3-D Salt DataSEG 3-D Salt Data
Horizontal Slice (Depth=1.4 km)Horizontal Slice (Depth=1.4 km)
CPU:CPU:1/170 1/170
CPU:CPU:1/33 1/33
CPU:CPU:1 1
2-D KM of a Single Trace2-D KM of a Single Trace
RR SSAA
AA
BB
BB
CC
CC
2-D WM of a Single Trace2-D WM of a Single Trace
RR SSAA
BBCC
AABB
CC
Traveltime + Ray DirectionTraveltime + Ray Direction
TrueReflection point
SmallMigration Aperture
FewerFewerArtifactsArtifacts
LessLessExpensiveExpensive
Wavepath MigrationWavepath Migration
OutlineOutline
• WM Crosswell ImagingWM Crosswell Imaging• Synthetic Crosswell Data Synthetic Crosswell Data • McElroy Crosswell DataMcElroy Crosswell Data• Synthetic Single Well DataSynthetic Single Well Data• ConclusionsConclusions
KM Crosswell ImagingKM Crosswell ImagingReceiver Receiver
WellWell
Up-goingUp-going
Down-goingDown-going
Interface 2Interface 2
Source Source WellWell
Interface 1Interface 1
KM Crosswell ImagingKM Crosswell ImagingReceiver Receiver
WellWell
Up-goingUp-going
Interface 2Interface 2
Source Source WellWell
Interface 1Interface 1
KM Crosswell ImagingKM Crosswell ImagingReceiver Receiver
WellWellDown-goingDown-going
Interface 2Interface 2
Source Source WellWell
Interface 1Interface 1
KM Crosswell ImagingKM Crosswell ImagingReceiver Receiver
WellWell
Up-goingUp-going
Down-goingDown-going
Interface 2Interface 2
Source Source WellWell
Interface 1Interface 1
Problems in KM Crosswell ImagingProblems in KM Crosswell Imaging
• Insufficient Stacking Leads to ArtifactsInsufficient Stacking Leads to Artifacts
• Complex Data Cause Difficulty inComplex Data Cause Difficulty in Up-going and Down-going SeparationUp-going and Down-going Separation
• Slow ComputationSlow Computation
WM Crosswell ImagingWM Crosswell ImagingReceiver Receiver
WellWell
Up-goingUp-going
Down-goingDown-going
Interface 2Interface 2
Source Source WellWell
Interface 1Interface 1
Advantages of WM Crosswell ImagingAdvantages of WM Crosswell Imaging
• Avoid Artifacts by Migrating to theAvoid Artifacts by Migrating to the Primary Reflection PointPrimary Reflection Point
• Handle Complex Data by MigratingHandle Complex Data by Migrating Up-going and Down-going togetherUp-going and Down-going together
• No Constraints NeededNo Constraints Needed
• Fast ComputationFast Computation
Shortcomings of WMShortcomings of WM
• Weaker EventsWeaker Events
• Worse Interface ContinuityWorse Interface Continuity
OutlineOutline
• WM Crosswell ImagingWM Crosswell Imaging• Synthetic Crosswell Data Synthetic Crosswell Data • McElroy Crosswell DataMcElroy Crosswell Data• Synthetic Single Well DataSynthetic Single Well Data• ConclusionsConclusions
Fault ModelFault Model A Common Shot GatherA Common Shot Gather
00 0000
9090
210210
210210
0.20.2
00Offset (m)Offset (m)
De
pth
(m
)D
ep
th (
m)
Tim
e (
s)T
ime
(s)
Geophone Depth (m)Geophone Depth (m)
ModelModel
Crosswell Imaging of Synthetic Fault Data Crosswell Imaging of Synthetic Fault Data
Offset: 0~90 m, Depth: 0~210 mOffset: 0~90 m, Depth: 0~210 m
WMWMKM KM WM (no separation)WM (no separation)
Better ImageBetter ImageBetter ResolutionBetter Resolution
OutlineOutline
• WM Crosswell ImagingWM Crosswell Imaging• Synthetic Crosswell Data Synthetic Crosswell Data • McElroy Crosswell DataMcElroy Crosswell Data• Synthetic Single Well DataSynthetic Single Well Data• ConclusionsConclusions
A Common Shot GatherA Common Shot Gather
811811 963963
0.050.05
00
Tim
e (
s)T
ime
(s)
Hydrophone Depth (m)Hydrophone Depth (m)
Traveltime TomogramTraveltime Tomogram
00
8118115656
963963
Offset (m)Offset (m)
De
pth
(m
)D
ep
th (
m)
6.76.7
4.74.7
(k
m /s
)(k
m /s
)
De
pth
(m
)D
ep
th (
m)
KM ImageKM Image
00 5656Offset (m)Offset (m)
Receiver WellReceiver WellSource WellSource Well
811811
963963SyntheticSyntheticSyntheticSynthetic
Up-goingUp-going
Down-goingDown-going
SeparationSeparation
??
??
De
pth
(m
)D
ep
th (
m)
Receiver WellReceiver WellSource WellSource Well
811811
963963SyntheticSyntheticSyntheticSynthetic
Up-goingUp-going
Down-goingDown-going
SeparationSeparation
WM ImageWM Image
00 5656Offset (m)Offset (m)
WM ImageWM Image
00 5656Offset (m)Offset (m)
De
pth
(m
)D
ep
th (
m)
Receiver WellReceiver WellSource WellSource Well
811811
963963SyntheticSyntheticSyntheticSynthetic
Up-goingUp-going
Down-goingDown-going
NO SeparationNO Separation
Receiver WellReceiver Well
SyntheticSynthetic
Source WellSource Well
SyntheticSynthetic
WM (up+down)WM (up+down)WM(CPU=1)WM(CPU=1)KM(CPU=2.5)KM(CPU=2.5)
Offset: 0~56 m, Depth: 811~963 mOffset: 0~56 m, Depth: 811~963 m
OutlineOutline
• WM Crosswell ImagingWM Crosswell Imaging• Synthetic Crosswell Data Synthetic Crosswell Data • McElroy Crosswell DataMcElroy Crosswell Data• Synthetic Single Well DataSynthetic Single Well Data• ConclusionsConclusions
OYO Salt ModelOYO Salt Model
9900
Velocity (km/s)Velocity (km/s)
00
66
Offset (km)Offset (km)
De
pth
(k
m)
De
pth
(k
m)
WellWell
SaltSalt
? ? ? ?? ? ? ?
????
????
4.54.52.82.8
KM imageKM image22
55
Dep
th (
km)
Dep
th (
km)
6.56.52.52.5 Offset (km)Offset (km) 6.56.52.52.5 Offset (km)Offset (km) 6.56.52.52.5 Offset (km)Offset (km)
OYO Salt ModelOYO Salt Model
Velocity ModelVelocity Model WM imageWM image
????
????
????? ?????
WellWell
ConclusionsConclusions
Crosswell Synthetic DataCrosswell Synthetic Data• Fewer migration artifactsFewer migration artifacts• Slightly better image resolutionSlightly better image resolution• Better for dipping fault boundaryBetter for dipping fault boundary• No up- and down-going separationNo up- and down-going separation
ConclusionsConclusions
Crosswell McElroy DataCrosswell McElroy Data• Similar image qualitySimilar image quality• No up- and down-going separationNo up- and down-going separation• 2.5 times faster than KM2.5 times faster than KM• Worse image continuityWorse image continuity• Structure details? Artificial events?Structure details? Artificial events?
ConclusionsConclusions
Single Well Synthetic DataSingle Well Synthetic Data• Similar image qualitySimilar image quality• Fewer migration artifactsFewer migration artifacts
AcknowledgementsAcknowledgements
I thank UTAM sponsorsI thank UTAM sponsorsfor their financial supportfor their financial support