Open Journal of Applied Sciences, 2013, 3, 84-88
doi:10.4236/ojapps.2013.31B1017 Published Online April 2013 (http://www.scirp.org/journal/ojapps)
Reliability of Attenuation Properties Recovery for
Viscoelastic Media
Ekaterina Efimova, Vladimir Cheverda
The laboratory “Numerical methods of inversion of geophysical wavefields”, A.A. Trofimuk Institute of Petroleum
Geology and Geophysics SB RAS. Novosibirsk, Russia
Email: EfimovaES@ipgg.sbras.ru
Received 2013
ABSTRACT
The inverse problem of seismology for media with attenuation is considered in this paper. Generalized Standard Linear
Solid is used to describe viscoelastic media. In the numerical solution certain parameterizations can be coupled, it
means that true heterogeneity of the only one of parameters can be restored only as a perturbation of another. This is
why important to investigate reliability of parameters recovery. By using method based on diffraction patterns it is pos-
sible to see whether the parameters are coupled. Singular value decomposition was used to study the possibility of re-
covering the parameters in practice. It was investigated the possibility of reconstructing of the density, impedances and
attenuation properties. Coupling appears on the attenuation properties and impedances separately corresponding to the
P-wave and S-wave. It is also should be noted that coupling decreases with increasing frequency range and the condi-
tion number.
Keywords: Viscoelasticity; Seismic Attenuation; Inverse Theory; Wave Propagation; Singular Value Decomposition;
Diffraction Patterns
1. Introduction
The main theme of the work is recovery of characteristics
of viscoelastic media. For this purpose was considered
numerical solution of two-dimensional inverse problem
of seismology using the information recorded in the re-
ceivers located on the surface of the Earth. It is known
that a numerical model of viscoelastic media describes
the geological structures, in particular hydrocarbon res-
ervoirs. And the attenuation properties depend on the
composition of the fluid.
But there appears coupling of parameters of the me-
dium in the numerical formulation of the problem that
will be discussed in this article. Coupling of parameters
means that the true heterogeneity of only one parameter
would restore as a perturbation of other in the numerical
solution. So if you use coupled parameters, your solution
will be incorrect. Therefore, we need to find uncoupled
set of parameters before developing and implementation
of the algorithm.
Determination the possibility of uncoupled reconstruc-
tion of the parameters of a viscoelastic medium, such as
density, elastic impedances and attenuation properties is
the subject of this research.
This problem was considered in other papers, in par-
ticular, in [1], the problem was solved for the case of
media with a velocity close to a constant value. There
was also shown the inability simultaneous recovery of
the velocity and attenuation properties in viscoelastic
media without additional conditions [2].
2. Numerical Description of Viscoelastic
Media
State equation provides the relationship between stresses
and strains at the same time for ideal elastic media. But
this is not true in viscoelastic media, which possess at-
tenuation that caused by memory of the material. For
such media stress state depends on all past states of
strains and the state equation can be expressed with the
use of the generalized Hooke's law. Media with attenua-
tion mathematically can be described by the system of
equations:
/
*
/ ( )/2
(,) ( , )/ (, ) .
t
kl ijkl
u t div f
t u u
x t x G xt
ij
d
(1)
2.1. Generalized Standard Linear Solid
Numerical resolution of such integral-differential system
is very troublesome, so it is proposed to use Standard
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