Migration In a Nutshell Migration In a Nutshell Migration In a Nutshell D.S. Macpherson.
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Transcript of Migration In a Nutshell Migration In a Nutshell Migration In a Nutshell D.S. Macpherson.
Migration
In a
NutshellMigration
In a
NutshellMigration
In a
Nutshell
D.S. MacphersonD.S. Macpherson
- The problem with stackingA. The nature of the seismic image
Migrating the seismic imageon to the plane of the reflector
Un-migratedstacked data
Migratedimage
Un-migratedimage surface
Migratedimage surface
A - 17
F. Imaging by seismic migration
Un-migrated trace
Migrated trace
- Kirchhoff summation
F - 9
F. Imaging by seismic migration
Reflector surface
Migration of stacked (ZSR) traceby Kirchhoff summation
- Kirchhoff summation
F - 10
F. Imaging by seismic migration
Migration of a diffractionby Kirchhoff summation
Diffraction hyperbola
- Kirchhoff summation
F - 13
F. Imaging by seismic migration
Un-migrated stack
Migrated stack
- Kirchhoff summation
F - 15
Un-migrated Model
E. Seismic data processing - Pre-stack migration
E - 26
Migrated ModelEnd effect fromthe model
Migration noise
E. Seismic data processing - Pre-stack migration
E - 25
Decimated Model(Every fifth trace)
E. Seismic data processing - Pre-stack migration
E - 27
Migrated Model(Single offset - 600 feet)
E. Seismic data processing - Pre-stack migration
E - 28
TRACE SWEEPAMIMATION
POSTSTACK
A B C D
Source Receiver
A A
A B C D
Source Receiver
B B
A B C D
Source Receiver
C C
A B C D
Source Receiver
D D
Composite
A B C D
F. Imaging by seismic migration
Reflector surface
Migration of stacked (ZSR) traceby Kirchhoff summation
- Kirchhoff summation
F - 10
Seismic section in depth showing productive intervals
Case 3 6
- The problem with stacking
Common mid-point
Moveout in the presence of dip
Stackedtrace
Moveoutcorrected
traces
Commonmid-point
gather
F. Imaging by seismic migration
F - 16
SourceLocation
ReceiverLocation
Single Seismic TracePre-stack Migrated
E. Seismic data processing - Prestack migration
E - 24
- The problem with stacking
Common mid-point
Image point gather
Stackedtrace
Migratedtraces
Common imagepoint
Tracesin time
Common midpoint
Image pointwindow
3D bin size
F. Imaging by seismic migration
F - 17
PreStack MigrationEllipse Sweep
- The problem with stackingA. The nature of the seismic image
Common mid-point
Image point gather
Stackedtrace
Migratedtraces
Common imagepoint
Tracesin time
Common midpoint
Image pointwindow
3D bin size
A - 21
Common mid-point
Image pointwindow
3D bin size
Common mid-point
1
Common mid-point
2
Common mid-point
3
Common mid-point
4
Common mid-point
5
Common mid-point
6
Common mid-point
7
Common mid-point
8
Common mid-point
9
Image pointwindow
3D bin size
Image pointwindow
3D bin size
Migratedtraces
Common imagepoint
Stacking traces in the image point gather in
offset ranges
Image pointwindow
3D bin size
These are all stacked traces,
but they are stacked in
offset ranges
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 1Near offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 2
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 3
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Image pointwindow
3D bin size
Trace 4Far offsets
Common mid-pointCurrent offset
Migratedtraces
Common imagepoint
Ray Tracing for the Reflections in the
Gather
Image pointwindow
3D bin size
Migratedtraces
Common imagepoint
Trace 1Near offsets
Image pointwindow
3D bin size
Migratedtraces
Common imagepoint
Trace 2
Image pointwindow
3D bin size
Migratedtraces
Common imagepoint
Trace 3
Image pointwindow
3D bin size
Trace 4Far offsets
Migratedtraces
Common imagepoint
Common mid-point
Image pointwindow
3D bin size
So we started with this
Common mid-point
Image pointwindow
3D bin size
Image pointwindow
3D bin size
And ended up with this
AVO Display
TRACE SWEEPAMIMATION
PRESTACK
A B C D
Source Receiver
A A
A B C D
Source Receiver
A B
A B C D
Source Receiver
A C
A B C D
Source Receiver
A D
A B C D
Source Receiver
B A
A B C D
Source Receiver
B B
A B C D
Source Receiver
B C
A B C D
Source Receiver
B D
A B C D
Source Receiver
C A
A B C D
Source Receiver
C B
A B C D
Source Receiver
C C
A B C D
Source Receiver
C D
A B C D
Source Receiver
D A
A B C D
Source Receiver
D B
A B C D
Source Receiver
D C
A B C D
Source Receiver
D D
Composite
A B C D
F. Imaging by seismic migration
V1V2
V3
V4
Dep
th
Dep
th
Dep
thT
ime
3D time (stacked) data cube
3D depth velocity model 3D ray tracing
3D “sweep” ray tracing
Iso-timecontours
- Depth migration
F - 22
Depth Migration Iso-time Map for the Shot Location
Depth Migration Iso-time Map for the Receiver Location
Depth Migration Iso-time Mapfor Both the Shot and Receiver Locations
The Sweep of a Single Prestack Trace
Link to TCHART.exe
- Displays in depth and timeA. The nature of the seismic image
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
De
pth
(Kilo
me
ters
)
Tim
e (S
ec
on
ds
)
A - 30
PRESTACKWAVE EQUATION
AMIMATION
SOURCE
RECIEVER
SOURCE RECIEVER
SOURCE RECIEVER
200 Millisecond Image
Source time60 ms.
Receiver time140 ms.
SOURCE RECIEVER
200 Millisecond Image
Source time70 ms.
Receiver time130 ms.
SOURCE RECIEVER
200 Millisecond Image
Source time80 ms.
Receiver time120 ms.
SOURCE RECIEVER
200 Millisecond Image
Source time90 ms.
Receiver time110 ms.
SOURCE RECIEVER
200 Millisecond Image
Source time100 ms.
Receiver time100 ms.
SOURCE RECIEVER
200 Millisecond Image
Source time110 ms.
Receiver time90 ms.
SOURCE RECIEVER
200 Millisecond Image
Source time120 ms.
Receiver time80 ms.
SOURCE RECIEVER
200 Millisecond Image
Source time130 ms.
Receiver time70 ms.
SOURCE RECIEVER
200 Millisecond Image
Source time140 ms.
Receiver time60 ms.
SOURCE RECIEVER
200 Millisecond Image
F. Imaging by seismic migration
3D Post-stack Time Migration
3D Pre-ststack Depth Migration
Data Courtesy of CGG
- Depth migration
F - 24