Scattering diagrams in seismic imaging: An integration of velocity estimation and migration

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Scattering diagrams in seismic imaging An
integration of velocity estimation and migration
Texas AM University
Luc T. Ikelle and Ilana Erez
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Bending the wrong way, imaging the right way.
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Contents

• Virtual events
• Movie
• Examples of virtual events
• Representation theorem
• Implications for seismic imaging
• Layer thicknesses revealed by virtual events
• Aperture of virtual events

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Seismic and virtual events
Free-surface multiple
Primary
Internal multiple
Virtual events
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Forward and backward propagation(horizontal)
t
t0
t1
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Forward and backward propagation(horizontal)
t
t0
t1
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Forward and backward propagation(dip)
t
t0
t1
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Forward and backward propagation(dip)
t
t0
t1
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Convention of diagrammatica and construction of
virtual events
g1
a1
b1


g2
a2
b2


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Seismic data
Raw data in shot and offset gathers
Divided data in shot and offset gathers
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Virtual events
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Renormalization
Virtual events without renormalization
Virtual events with renormalization
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Construction of primaries and internal multiples
Predicted data with renormalization
Predicted data without renormalization
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Construction of internal multiples
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Internal multiple attenuation
Virtual events without virtual direct
wave (autocorrelation)
Virtual events with virtual direct
wave (autocorrelation)
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Internal multiple attenuation
Predicted internal multiples
Demultipled data
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Internal multiple attenuation
The original data (notice the multiples at
t2.28s)
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Internal multiple attenuation
Demultipled data (no iter )
Demultipled data (step 1)
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The representation theorem
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References Bojarski (1983), de Hoop (1985),
Gangi (1970), and Ikelle and Admunsen (2005)
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Convolution type
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Correlation type
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Correlation type
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Contents

• Virtual events
• Movie
• Examples of virtual events
• Representation theorem
• Implications for seismic imaging
• Layer thicknesses revealed by virtual events
• Aperture of virtual events

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Bending the wrong way, imaging the right way.
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Imaging
Physical meaning

• Virtual event represents the time a wave spent in
  second or/and third layers only, depending on the
  scattering point of the second event in the real
  data. So, the time it takes to the wave to travel
  through the layers above is canceled out.

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Layer thicknesses revealed by virtual events
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