Difference between revisions of "Aspects of 3-D prestack time migration — a summary"

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# The 3-D image volume can be inverse migrated by way of 3-D zero-offset wavefield modeling to derive an unmigrated 3-D zero-offset data volume.
 
# The 3-D image volume can be inverse migrated by way of 3-D zero-offset wavefield modeling to derive an unmigrated 3-D zero-offset data volume.
 
# The 3-D rms velocity field estimated from the 3-D prestack time-migrated data, as from step (f) of the workflow described above, can be used to derive a 3-D interval velocity field by [[Dix conversion]].
 
# The 3-D rms velocity field estimated from the 3-D prestack time-migrated data, as from step (f) of the workflow described above, can be used to derive a 3-D interval velocity field by [[Dix conversion]].
# Finally, the 3-D interval velocity field and the 3-D zero-offset wavefield can be used to derive an earth image in depth by [[3-D poststack depth migration]]. The earth image volume in depth can then be interpreted to delineate a set of reflector geometries associated with key geological markers. The interval velocity field combined with the reflector geometries may be used to build an initial earth model in depth ([[earth modeling in depth]]).
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# Finally, the 3-D interval velocity field and the 3-D zero-offset wavefield can be used to derive an earth image in depth by [[3-D poststack depth migration]]. The earth image volume in depth can then be interpreted to delineate a set of reflector geometries associated with key geological markers. The interval velocity field combined with the reflector geometries may be used to build an initial earth model in depth ([[introduction to earth modeling in depth|earth modeling in depth]]).
 
 
<gallery>file:ch07_fig4-35.png|{{figure number|7.4-35}} A constant-velocity-stack (CVS) volume created from the 3-D DMO-corrected prestack data associated with the same 3-D survey as of the data shown in Figure 7.4-33 using a velocity of 2400 m/s.
 
file:ch07_fig4-36.png|{{figure number|7.4-36}} A constant-velocity-[[migration]] (CVM) volume created by migrating the constant-velocity-stack (CVS) volume shown in Figure 7.4-35 using a velocity of 2400 m/s.
 
file:ch07_fig4-37.png|{{figure number|7.4-37}} (a) A velocity volume created by extracting the [[time slices|time slice]] at 2000 ms from each of the constant-velocity-[[migration]] (CVM) volumes as in Figure 7.4-36, (b) the velocity strands picked from the velocity volume in (a).
 
file:ch07_fig4-38a.png|{{figure number|7.4-38}} Part 1: The super volume created by brick-layering the velocity volumes as in Figure 7.4-37a associated with 26 time levels as listed.
 
file:ch07_fig4-38b.png|{{figure number|7.4-38}} Part 2: A close-up view of the super volume shown in Figure 7.4-38a.
 
file:ch07_fig4-39a.png|{{figure number|7.4-39}} Part 1: The rms velocity maps created by gridfitting the control points represented by the velocity strands as in Figure 7.4-37b for time levels as labeled.
 
file:ch07_fig4-39b.png|{{figure number|7.4-39}} Part 2: The rms velocity maps created by gridfitting the control points represented by the velocity strands as in Figure 7.4-37b for time levels as labeled.
 
file:ch07_fig4-39c.png|{{figure number|7.4-39}} Part 3: The rms velocity maps created by gridfitting the control points represented by the velocity strands as in Figure 7.4-37b for time levels as labeled.
 
file:ch07_fig4-39d.png|{{figure number|7.4-39}} Part 4: The rms velocity maps created by gridfitting the control points represented by the velocity strands as in Figure 7.4-37b for time levels as labeled.
 
file:ch07_fig4-40a.png|{{figure number|7.4-40}} Part 1: Selected inline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
file:ch07_fig4-40b.png|{{figure number|7.4-40}} Part 2: Selected inline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
file:ch07_fig4-40c.png|{{figure number|7.4-40}} Part 3: Selected inline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
file:ch07_fig4-40d.png|{{figure number|7.4-40}} Part 4: Selected inline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
file:ch07_fig4-40e.png|{{figure number|7.4-40}} Part 5: Selected inline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
file:ch07_fig4-41a.png|{{figure number|7.4-41}} Part 1: Selected crossline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
file:ch07_fig4-41b.png|{{figure number|7.4-41}} Part 2: Selected crossline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
file:ch07_fig4-41c.png|{{figure number|7.4-41}} Part 3: Selected crossline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
file:ch07_fig4-41d.png|{{figure number|7.4-41}} Part 4: Selected crossline sections from the rms velocity volume created from the maps shown in Figure 7.4-39.
 
</gallery>
 
  
 
==See also==
 
==See also==

Latest revision as of 11:38, 1 October 2014

Seismic Data Analysis
Seismic-data-analysis.jpg
Series Investigations in Geophysics
Author Öz Yilmaz
DOI http://dx.doi.org/10.1190/1.9781560801580
ISBN ISBN 978-1-56080-094-1
Store SEG Online Store


The improvement in imaging with 3-D prestack time migration may sometimes be marginal compared to imaging with 3-D poststack time migration of 3-D DMO-stacked volume of data. Nevertheless, the benefits of 3-D prestack time migration are not limited to the improved image of the subsurface as listed below.

  1. 3-D prestack time migration is the appropriate strategy for imaging conflicting dips with different stacking velocities, such as reflections from steeply dipping fault planes with 3-D geometry and gently dipping strata.
  2. The 3-D image volume derived from 3-D prestack time migration is used as an input to 3-D zero-offset amplitude inversion to estimate an acoustic impedance model of the earth (acoustic impedance estimation).
  3. The CRP gathers from 3-D prestack time migration are used to perform prestack amplitude inversion to derive amplitude variation with offset (AVO) attributes (analysis of amplitude variation with offset).
  4. The 3-D image volume can be inverse migrated by way of 3-D zero-offset wavefield modeling to derive an unmigrated 3-D zero-offset data volume.
  5. The 3-D rms velocity field estimated from the 3-D prestack time-migrated data, as from step (f) of the workflow described above, can be used to derive a 3-D interval velocity field by Dix conversion.
  6. Finally, the 3-D interval velocity field and the 3-D zero-offset wavefield can be used to derive an earth image in depth by 3-D poststack depth migration. The earth image volume in depth can then be interpreted to delineate a set of reflector geometries associated with key geological markers. The interval velocity field combined with the reflector geometries may be used to build an initial earth model in depth (earth modeling in depth).

See also

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