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1

Efcient mixed domain pure P wave equations for 2D and 3D tilted transversely isotropic media

Li Bowen, Wang Deli, Zhou Jinju, Zhang Qianxiang, Wang Rui

Acta Geophysica

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2020

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Vol. 68, no. 3

605--618

EN

In transversely isotropic (TI) media, accurate and efcient pure P-wave extrapolation is the basis of seismic imaging and inversion algorithms. For pure P-wave equations in TI media, combining the fnite-diference (FD) method with the pseudospectral (PS) method is an efective solution. However, if the mixed-domain pure P-wave equation contains multiple wavenumbers, using the hybrid approach will involve multiple Fourier transforms, which will result in high computational costs. Referring to the weak anisotropy approximation, we propose a new approximate P-wave phase velocity expression. We then use an optimization strategy to reduce the number of wavenumber terms in the corresponding dispersion relations and derive the mixed-domain pure P-wave equations in 2D and 3D tilted transversely isotropic (TTI) media. Through numerical experiments in 2D and 3D TTI models, we verify the feasibility and efciency of the proposed mixed-domain P-wave equations.

2

Fluid identification based on P-wave anisotropy dispersion gradient inversion for fractured reservoirs

Zhang J. W., Huang H. D., Zhu B. H., Liao W.

Acta Geophysica

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2017

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Vol. 65, no. 5

1081--1093

EN

Fluid identification in fractured reservoirs is a challenging issue and has drawn increasing attentions. As aligned fractures in subsurface formations can induce anisotropy, we must choose parameters independent with azimuths to characterize fractures and fluid effects such as anisotropy parameters for fractured reservoirs. Anisotropy is often frequency dependent due to wave-induced fluid flow between pores and fractures. This property is conducive for identifying fluid type using azimuthal seismic data in fractured reservoirs. Through the numerical simulation based on Chapman model, we choose the P-wave anisotropy parameter dispersion gradient (PADG) as the new fluid factor. PADG is dependent both on average fracture radius and fluid type but independent on azimuths. When the aligned fractures in the reservoir are meter-scaled, gas-bearing layer could be accurately identified using PADG attribute. The reflection coefficient formula for horizontal transverse isotropy media by Rüger is reformulated and simplified according to frequency and the target function for inverting PADG based on frequency-dependent amplitude versus azimuth is derived. A spectral decomposition method combining Orthogonal Matching Pursuit and Wigner–Ville distribution is used to prepare the frequency-division data. Through application to synthetic data and real seismic data, the results suggest that the method is useful for gas identification in reservoirs with meter-scaled fractures using high-qualified seismic data.

3

P-wave interaction with a pair of rigid strips embedded in an orthotropic strip

Basu S., Mandal S. C.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 2

579--592

EN

The present paper is concerned with the problem of scattering of the P-wave by two co- -planer finite rigid strips placed symmetrically in an infinitely long orthotropic strip. Using the Hilbert transform technique, the mixed boundary value problem has been reduced to the solution of dual integral equations which has finally been reduced to the solution of a Fredholm integral equation of the second kind. Solving this integral equation numerically, stress intensity factors have been calculated at the inner and outer edges of the rigid strips, and the vertical displacement outside the strips has been calculated and plotted graphically to show the effect of material orthotropy.

4

Reflection of P-wave and SV-wave in a generalized two temperature thermoelastic half-space

Santra S., Lahiri A., Das N. C.

International Journal of Applied Mechanics and Engineering

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2014

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Vol. 19, no. 4

735--754

EN

In this work the theory of two temperature generalized thermoelasticity has been used to investigate the problem of reflection of P-wave and SV-wave in a half space when the surface is i) thermally insulated or ii) isothermal. The ratios of the reflection coefficient to that of the incident coefficient for different cases are obtained for P-wave and SV-waves. The results for various cases for the conductive and dynamical temperature have been compared. The results arrived at in the absence of the thermal field (elastic case) have also been compared with those in the existing literature. Finally, the results for various cases have been analyzed and depicted in graphs.

5

Opracowanie rozkładu prędkości fal P i S z głębokością przy wykorzystaniu programu ESTYMACJA i danych geofizyki otworowej w rejonie wschodniej części zapadliska przedkarpackiego

Bała M., Witek K.

Prace Instytutu Nafty i Gazu

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2004

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nr 130

255--259

PL

Obliczono czasy interwałowe fal podłużnych i poprzecznych (DPEQ i DSEQ) oraz prędkości (Vp i Vs) z głębokością na podstawie pomiarów geofizyki wiertniczej i przeprowadzonej interpretacji ilościowej [projekt celowy pt: „Opracowanie kryteriów sejsmicznej lokalizacji złóż węglowodorów dla warunków zapadliska przedkarpackiego w oparciu o nowe techniki trójskładowych pomiarów sejsmicznych (3C) i modelowań całkowitego pola falowego", kierownik K. Pietsch i E. Gruszczyk]. Do obliczeń wykorzystano program o nazwie ESTYMACJA opracowany przez M. Bałę i A. Cichego w ramach projektu badawczego nr 8 T12B 046 20 [1]. Na podstawie obliczonych Vp i Vs opracowano model prędkościowy dla wschodniej części zapadliska przedkarpackiego.

EN

Velocity and interval time P-wave and S-wave was calculated based on well logging data and numerical interpretation (project No 6T12 2003 C/06006, manager: K. Pietsch, E.Gruszczyk). For these calculations was used application ESTYMACJA. This program was created by M. Bała and A.Cichy based on calculated velocity P-wave and S-wave created velocity model for East part of Carpatian Foredeep.

6

P-wave amplitudes and dynamic strains inside the earth

Duda S., Jansky J., Kvasnicka M.

Acta Geophysica Polonica

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2000

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Vol. 48, nr 2

179-193

EN

The isolines of P-wave amplitudes in the mantle radiated from a point source in the IASP91 velocity Earth model with the AK135 density and Q distribution are presented. The zero-order ray method is used for the computation. The amplitude isolines are given for three signal periods and three source depths for a point source and for a symmetric radiation pattern. The influence of the double-couple radiation is considered. The form of amplitude isolines is found to depend on the period of the propagating signal, due to the different attenuation, as well as on the radiation pattern and to lesser extent on the depth of the source. Finally, examples of isolines of the P-wave strain generated during the propagation are presented for different periods.