WaveEquation Interferometric Migration of VSP Data - PowerPoint PPT Presentation

Title: WaveEquation Interferometric Migration of VSP Data


1
Wave-Equation Interferometric Migration of VSP
Data

• Ruiqing He
• Dept. of Geology Geophysics
• University of Utah

2
Outline

• Acknowledgements
• Introduction of Seismic Interferometry
• Wave-equation Interferometric Migration
• 3D Migration of VSP Multiples
• Salt Flank Imaging
• Conclusion Technical Contributions

3
Outline

• Acknowledgements
• Introduction of Seismic Interferometry
• Wave-equation Interferometric Migration
• 3D Migration of VSP Multiples
• Salt Flank Imaging
• Conclusion Technical Contributions

4
Acknowledgements

• Thank Jerry Schuster for enlightening lectures,
  innovating discussions, supervising and support.
• Thank Bob Smith, Cari Johnson, Kris Sikorski for
  teaching and supervising. Thank Yue Wang for
  supervising.
• Thank my family.

5
Outline

• Acknowledgements
• Introduction of Seismic Interferometry
• Wave-equation Interferometric Migration
• 3D Migration of VSP Multiples
• Salt Flank Imaging
• Conclusion Technical Contributions

6
Introduction of Seismic Interfeometry

• Passive Seismic Imaging
• Claerbout (1968)
• Katz (1990) Cole (1995)
• Daneshvar et al. (1995)

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Introduction of Seismic Interfeometry (continued)

• Daylight Imaging
• Rickett Claerbout (1996, 1999, 2000)
• Helioseismologists (Duvall et al., 1993)
• Schuster (1999,2000), Wapenaar (2003)

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Introduction of Seismic Interfeometry (continued)

• Virtual Source
• Calvert, Bakulin, et al. (2004)

Overburden
Target
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Introduction of Seismic Interfeometry (continued)

• Seismic Interferometry
• Schuster Rickett (1999)
• Schuster (2001)
• Yu Schuster (2001, 2006)
• Jiang et al. (2005)

• No restriction on source distribution
• Arbitrary velocity model
• Many types of events used

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Introduction of Seismic Interfeometry (continued)

• Seismic Interferometry Theory

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Introduction of Seismic Interfeometry (continued)

• Migration of VSP Multiples

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Introduction of Seismic Interfeometry (continued)

• Successful Applications

Xiao, et al. (2005)
UTAM report
Drilling
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Introduction of Seismic Interfeometry (continued)

• Robust Imaging

Kirchhoff Migration
KM
Overburden
IM
Interferometric Migration
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Introduction of Seismic Interfeometry (continued)

• Super Resolution

Kirchhoff Migration
Interferometric Migration
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Introduction of Seismic Interfeometry (continued)
CDP multiple migration
Various applications
VSP multiple migration
overburden
HSP imaging
Salt Dome
VSP salt flank imaging
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Outline

• Acknowledgements
• Introduction of Seismic Interferometry
• Wave-equation Interferometric Migration
• 3D Migration of VSP Multiples
• Salt Flank Imaging
• Conclusion Technical Contributions

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Wave-Equation Interferometric Migration (WEIM)
consideration
IVSP

• Kirchhoff Migration Costs
• Crosscorrelation
• Ray tracing
• Storage for traveltime tables
• For Example
• To obtain 85 x 87 x 1400 migration
• cube, 300 GB disk is required.

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WEIM theory
IVSP

• WEIM costs for one gather
• One wavefield extrapolation
• One ray tracing
• One traveltime table

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Ray Tracing
Unknown medium
Known medium
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3D WEIM of VSP Multiples
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2D Synthetic Test
Synthetic model
Synthetic data
600 shots
0
0
Time (s)
12 geophpnes
Depth (m)
Multiples
5
4000
0
Offset (m)
0
6000
Offset (m)
6000
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Migration Comparison
Migration of primaries
Migration of multiples
0
0
Depth (m)
Depth (m)
4000
4000
0
Offset (m)
0
6000
Offset (m)
6000
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Field Data Application
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Survey Geometry
11 km
11 km
3 similar spirals, each corresponding to an
offset-ed geophone group.
Each geophone group has 12 geophones.
5 km deep
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3D WEIM Result
Migration of only one receiver gather
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Slice Movie
Migration of only one receiver gather
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Slice of 3D Migration Cube
0
Depth (m)
6500
Offset (m)
11000
0
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Common Image Gather
0
Depth (m)
6500
Offset (m)
1
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VSP Salt Flank Imaging
Overburden
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Interferometric Migration Result
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A Synthetic Experiment
10 shots
Overburden
94 geophones
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A Shot Gather
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WEIM Result (one shot)
2700
Depth (m)
Artifacts
5500
0
1700
Offset (m)
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WEIM Result (ten shots)
2700
Depth (m)
5500
0
1700
Offset (m)
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Outline

• Acknowledgements
• Introduction of Seismic Interferometry
• Wave-equation Interferometric Migration
• 3D Migration of VSP Multiples
• Salt Flank Imaging
• Conclusion Technical Contributions

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Conclusion

• Seismic interferometry is a robust imaging tool,
  and has a variety of applications.
• However, the relatively weak energy waves and low
  fold imaging in some applications could result in
  the low S/N ratio of the image.

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Technical Contributions (I)

• Wave-equation interferometric migration is
  proposed for efficient 3D migration of VSP
  multiples.
• It is as robust to velocity estimation errors as
  surface seismic imaging.
• It is much more cost efficient than surface
  seismic surveys in obtaining a 3D subsurface
  image volume.
• It might be also useful for time-lapse (4D)
  seismic monitoring for some oil fields.

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Technical Contributions (II)

• Apply interferometric migration to salt flank
  imaging with VSP data
• A huge chunk of overburden is ignored, so that
  the imaging is not only efficient, but also
  robust to velocity estimation errors.
• Other vertical structures, such as faults that
  are difficult to image by surface seismic surveys
  could also be imaged.

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The End

• Thank you.