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JOURNAL OF SEISMIC EXPLORATION
SEISMIC APPLICATIONS
book series
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Contents
& Abstracts Journal of Seismic Exploration
Volume
16, Number 1, July 2007
Volume 16, Number 2-4,
December 2007
Volume 17, Number 1,
February 2008
Volume 17, Number 2-3,
April 2008
Volume 17, Number 4, September 2008
Volume 18, Number 1, January
2009
Volume 18, Number 2, April
2009
Volume 18, Number 3, July
2009
Volume 18, Number 4, October
2009
Volume 19, Number
1, January 2010
Volume 19, Number
2, April 2010
Volume 19, Number
3, July 2010
Volume 19, Number
4, October 2010
Volume 20, Number
1, February 2011
Volume 20, Number
2, May 2011
Volume 20, Number
3, September 2011
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| ABSTRACTS
Vol. 17, No. 4, September 2008 |
Deng, F. and McMechan, G.A., 2008.
3D true-amplitude prestack depth migration.
The angle-dependent reflectivity of a reservoir target is crucial
input for reservoir characterization. 3D prestack depth migration
should be able to produce not only an accurate structural image,
but also reliable angle-dependent amplitude information. However,
none of the currently available 3D migration algorithms satisfy
this requirement. Geometrical spreading is the only consideration
in most existing true-amplitude migrations; intrinsic attenuation,
and transmission losses also distort the wavefield amplitudes
during propagation through the earth. We develop an integrated
algorithm that compensates all three of these factors, in a
two-pass recursive reverse-time 3D prestack depth migration.
Applications to 3D synthetic models demonstrate production of
both high quality subsurface images and angle-dependent (prestack)
reflection coefficients at the target. The velocity ratio at
the target is also obtained by least square fitting over the
estimated angle-dependent reflection coefficients. Because of
the nature of reverse-time migration and the recursive procedure,
the 3D algorithm is computationally and memory intensive. However,
for application to real seismic data, 3D true amplitude processing
is necessary. |
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Verschuur, D.J., 2008. Tracking
of seismic events using a combined global and local optimization
strategy.
Some seismic processing algorithms require a smooth and continuous
track of a seismic event in a multi-dimensional domain. Often
tracking algorithms are based on trace-to-trace correlations
and have a local search character. They show a discontinuous
behavior, are sensitive to cycle-skipping and cannot bridge
bad data zones. Therefore, it is proposed to design a multi-dimensional
tracking algorithm that is based on a global solution that can
avoid local minima and can be optimally guided by the user.
To keep the algorithm efficient, a hybrid optimization strategy
is developed, in which a global optimization method - being
a genetic algorithm - is combined with a local optimization
method - the simplex algorithm. Both 2D and 3D tracking algorithms
are described based on spline functions, where the knots of
the splines represent the variables of the optimization algorithm.
Results on field data show the effectiveness of the tracking
procedure for various tracking problems. |
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Keydar, S. and Mikenberg, M.,
2008. A new time correction formula in three-dimensional media
as a function of wavefront attributes.
A new travel-time correction formula for three-dimensional media
expresses move-out as a function of wavefront attributes, such
as radii of curvatures of wavefronts and angles of incidence.
The formula is a travel-time approximation based on a Taylor
series expansion, and is obtained by using only the eikonal
equation and basic principles of differential geometry. For
a given source-receiver pair, the move-out equations express
the move-out correction with respect to a zero-offset trace
by five parameters measured at the point where zero-offset trace
starts (common shot point, CSP). The parameters are: the two
principal radii of curvature of the wavefront, the angle defining
the orientation of the principal axes, the emergence angle and
azimuth. If, in addition, one of the principal planes of the
wavefront (planes normal to the wavefront and containing principle
radii of the curvature) is normal to the acquisition surface
as well, the number of parameters is reduced to four. Four examples
with different three-dimensional wavefronts confirm the accuracy
and establish the range of validity of the travel-time approximation. |
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Yan,
J., Lubbe, R. and Pillar, N., 2008. Modified velocity model
for seismic study via AVO.
AVO analysis in rock physics links petrophysical and geophysical
data, it requires knowledge of the relationships of P and S-wave
velocities, volume of shale, bulk density, mineral and fluid
properties and relevant reservoir parameters (such as porosity,
water saturation etc). We designed a semi-empirical-theoretical
model to predict velocities based on well-log data which can
then be linked to the seismic velocities via an AVO modelling.
This method is based on the differential effective medium (DEM)
scheme and the properties of randomly distributed sand grains,
shale content, varying aspect ratios and related rock parameters.
The model could be regarded as an extension of the Xu-White
(1995) model. Tests using this model on field data from the
North Sea show good agreements between the predicted and measured
velocities and a satisfied AVO result can be achieved. |
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