ESCI 444Exploration Geophysics II Reflection Seismic Data Processing

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ESCI 444-Exploration Geophysics IIReflection
Seismic Data Processing
Spring, 2007

• Steve H. Danbom, Ph.D., P.G.
• Adjunct Professor
• Office - Room 206A
• Office Hours By Appointment

Lecture Week 8 Processing seismic
reflections migration
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ProMax overview statement on Migration as the
term applies to seismic reflection data.
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Further discussion of Migration.
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Still further discussion of Migration.
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Here is an example migration problem associated
with using the seismic reflection method in
imaging steep dip.
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Migration 101
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Constant velocity migration
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Examine point diffraction using (1)
normal-incidence reflectivity, (2) Huygens
Principle the exploding reflector, and (3) a
series of such points that would define a
reflecting surface.
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Constant velocity migration
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From Oz Yilmaz, Volume I, p. 483
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From Oz Yilmaz, Volume I, p. 483
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From Oz Yilmaz, Volume I, p. 483
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From Oz Yilmaz, Volume I, p. 483
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From Oz Yilmaz, Volume I, p. 483
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From Oz Yilmaz, Volume I, p. 484
Summation along the hyperbolic path defined by
t2 ?2 4x2/V2RMS
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From Oz Yilmaz, Volume I, p. 484
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Schematic that shows the imaging problem for a
simple anticline.
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Fermats Least-Time Principle
A light ray traveling from one point to another
will follow a path such that, compared with
nearby paths, the time required is either a
minimum or a maximum or will remain unchanged
(it the ray will remain stationary).
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Schematic that shows the imaging problem for a
simple syncline.
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Bow-tie effect in seismic imaging that is the
consequence of trying to image a bowl that has
a buried focus.
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Schematic that shows the imaging problem for a
vertical fault.
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Schematic that shows the imaging problem for a
30-degree fault.
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Schematic that shows the imaging problem for a
reef model.
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From Oz Yilmaz, Volume I, pp. 463-486.
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French model to demonstrate the value of 3-D
migration
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IFP Marmousi earth model used to compare the
effectiveness of various migration procedures.
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From Oz Yilmaz, Volume I, pp. 463-486.
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General discussion of the term Dip Moveout (DMO)
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DMO is a seismic processing operation to correct
for the fact that, for dipping reflections, the
traces of a CMP gather do not involve a common
reflecting point e.g., line 1.
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Discussion on various types of migration methods.
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Keep this in mind.
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Oz example section with 3-D post-stack time
migration
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Oz example section with 3-D pre-stack depth
migration
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