Wyniki wyszukiwania - BazTech

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Obliczanie inwersji sejsmicznej na azymutalnych transformacjach PPS-WPG fal podłużnych i poprzecznych

Bartoń R.

Nafta-Gaz

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2015

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R. 71, nr 10

711--719

PL

W artykule przedstawiono wyniki obliczeń inwersji sejsmicznej wykonywanej na azymutalnych transformacjach PPS-WPG fal podłużnych PP i poprzecznych PS. Realizacja przedmiotowego zadania była prowadzona na zarejestrowanych wieloazymutalnych pomiarach PPS 3C, pochodzących z północnego obszaru Polski. Otrzymane rezultaty użycia inwersji sejsmicznej, obliczanej metodą rekursywną, na transformacjach PPS-WPG wskazują, że metoda ta daje zadowalające wyniki do wyznaczania rozkładu zmienności prędkości akustycznych i gęstości w strefie okołootworowej.

EN

This article presents results of seismic inversion calculation, on VSP-CDP azimuthal transformations for longitudinal PP and transverse PS waves. Implementation of this task was performed on recorded VSP 3C multi-azimuthal measurements from northern Poland. The results of seismic inversion, calculated by recursive method on VSP-CDP transformations, indicate that this method provides satisfactory results for the determination of variability acoustic velocity and density distribution in a wellbore zone.

2

Reflection and transmission of plane waves between two different fluid saturated porous half spaces

Kumar R., Miglani A., Kumar S.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2011

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Vol. 59, nr 2

227-234

EN

The present study is concerned with the reflection and transmission of plane waves between two different fluid saturated porous half spaces when longitudinal and transversal waves impinge obliquely at the interface. Amplitude ratios of various reflected and transmitted waves are obtained .The variations of amplitude ratios with angle of incidence are depicted graphically. A particular case of reflection at the free surface in fluid saturated porous half spaces has been deduced and discussed. A special case of interest has also been deduced from the present investigation.

3

Influence of coupling through porosity changes on the propagation of acoustic waves in linear poroelastic materials

Albers B., Wilmanski K.

Archives of Mechanics

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2006

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Vol. 58, nr 4-5

313-325

EN

In earlier works it has been shown that linearization of thermodynamical models of poroelastic materials yields a contribution to stresses in the form ......., where ... is the current porosity, ... denotes its value in the thermodynamical equilibrium and ... is a material parameter. It has been also claimed on the basis of rough estimates that this parameter gives only negligible contributions to the properties of acoustic waves. The purpose of this work is twofold. We investigate the influence of ß on the propagation of acoustic waves in more details. We use the full linear model of saturated poroelastic materials in which an additional coupling to porosity changes appears. This results from the presence of a term with the porosity gradient in the momentum sources. Such a model becomes identical with Biot's model without any added mass contribution in the limit if infinite relaxation time of porosity ... and for the parameters ß=0, and N=0, where the latter is describing the above mentioned influence of porosity gradient on the momentum sources. The analysis of influence of the parameter N, i.e. the influence of the porosity gradient on properties of acoustic waves, is the second purpose of this work. We also indicate a correction of the permeability contribution to the momentum source. The permeability coefficient ... is assumed in Biot's model to be dependent on the frequency. This is inconsistent with other temporal contributions to field equations. In order to obtain such a dependence in the Fourier space, one has to assume a viscous effect to enter the momentum source and we do so in the general equations. However, we do not use this general relation in the analysis of monochromatic waves.

4

Propagacja fali podłużnej w uogólnionym materiale lepkosprężystym

Jankowski J.

Vibrations in Physical Systems

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2000

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Vol. 19

142--143

5

Propagation and attenuation of seismic body waves in initially stressed dissipative medium

Dey S., Dutta D.

Acta Geophysica Polonica

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1998

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Vol. 46, nr 3

351-366

EN

The paper discussed the effect of initial stresses on the propagation and attenuation of seismic body waves in a dissipative medium. The study reveals that the presence of initial stresses has strong effect in the propagation and attenuation of seismic waves. The velocity of waves depends on the direction of propagation and pure longitudinal and transverse waves are available only in the direction of initial stress and perpendicular to it. In other directions, a longitudinal wave is accompanied by some rotation and a transverse wave by some dilatation. The study also shows that the presence of compressive initial stress increases the velocity of longitudinal wave but diminishes that of trahsverse wave. It is also observed taht the loss of longitudinal wave due to dissipation is maximum in the initially stress-free case and decreases as the initial stress increases. In the case of SV wave, the presence of initil stresses decreases the loss factor upto the point when the direction of propagation makes an angle of 55° with the direction of initial stress, and then increases.