scholarly journals Effect of fluid viscosity on elastic wave attenuation in porous rocks

1999 ◽  
Author(s):  
Boris Gurevich
Keyword(s):  
Elastic Wave ◽  
Wave Attenuation ◽  
Fluid Viscosity ◽  
Porous Rocks

scholarly journals Water saturation effects on elastic wave attenuation in porous rocks with aligned fractures

2014 ◽  
Vol 197 (2) ◽  
pp. 943-947 ◽  
Author(s):  
Kelvin Amalokwu ◽  
Angus I. Best ◽  
Jeremy Sothcott ◽  
Mark Chapman ◽  
Tim Minshull ◽  
...  
Keyword(s):  
Elastic Wave ◽  
Reservoir Characterization ◽  
Wave Attenuation ◽  
Water Saturation ◽  
Theoretical Models ◽  
Ultrasonic Pulse ◽  
Fracture Density ◽  
Porous Rocks ◽  
Saturation State ◽  
Hydrocarbon Reservoir

Abstract Elastic wave attenuation anisotropy in porous rocks with aligned fractures is of interest to seismic remote sensing of the Earth's structure and to hydrocarbon reservoir characterization in particular. We investigated the effect of partial water saturation on attenuation in fractured rocks in the laboratory by conducting ultrasonic pulse-echo measurements on synthetic, silica-cemented, sandstones with aligned penny-shaped voids (fracture density of 0.0298 ± 0.0077), chosen to simulate the effect of natural fractures in the Earth according to theoretical models. Our results show, for the first time, contrasting variations in the attenuation (Q−1) of P and S waves with water saturation in samples with and without fractures. The observed Qs/Qp ratios are indicative of saturation state and the presence or absence of fractures, offering an important new possibility for remote fluid detection and characterization.

STUDIES OF ELASTIC WAVE ATTENUATION IN POROUS MEDIA

Geophysics ◽  
1962 ◽  
Vol 27 (5) ◽  
pp. 569-589 ◽  
Author(s):  
M. R. J. Wyllie ◽  
G. H. F. Gardner ◽  
A. R. Gregory
Keyword(s):  
Porous Media ◽  
Elastic Wave ◽  
Wave Attenuation ◽  
Fluid Motion ◽  
Fluid Viscosity ◽  
Biot’S Theory ◽  
Biot's Theory ◽  
High Frequencies ◽  
Very High Frequencies

Elastic wave attenuation in porous media is due in part to the relative motion of the liquid and the solid. Biot’s theory expresses this component in terms of permeability, fluid viscosity, frequency, and the elastic constants of the material. Experiments were performed to measure attenuation in the frequency range f <20,000 cps by a resonant bar method; attempts to measure attenuation at very high frequencies gave more equivocal results. Alundum bars were used to test the validity of the theory, for with these the loss not due to fluid motion is relatively small. Experiments were also made with natural specimens of rock. These showed that when not subjected to compacting pressure both the velocities and decrements of specimens were affected chemically and physically by the presence of liquid pore saturants. It is concluded that Biot’s theory seems generally applicable to the determination of the fluid‐solid or “sloshing” losses in resonated porous media. There is still some doubt about the applicability of the theory in the case of measurements made by pulse techniques. The use of attenuation measurements as a logging technique, possibly to estimate permeability, is also discussed.

scholarly journals Numerical Modelling and Optimization of Two-Dimensional Phononic Band Gaps in Elastic Metamaterials with Square Inclusions

2021 ◽  
Vol 11 (7) ◽  
pp. 3124
Author(s):  
Alya Alhammadi ◽  
Jin-You Lu ◽  
Mahra Almheiri ◽  
Fatima Alzaabi ◽  
Zineb Matouk ◽  
...  
Keyword(s):  
Elastic Wave ◽  
Tungsten Carbide ◽  
Composite Structure ◽  
Elastic Waves ◽  
Wave Attenuation ◽  
Low Frequency ◽  
Filling Fraction ◽  
Carbide Composite ◽  
Elastic Metamaterials ◽  
Tungsten Carbide Composite

A numerical simulation study on elastic wave propagation of a phononic composite structure consisting of epoxy and tungsten carbide is presented for low-frequency elastic wave attenuation applications. The calculated dispersion curves of the epoxy/tungsten carbide composite show that the propagation of elastic waves is prohibited inside the periodic structure over a frequency range. To achieve a wide bandgap, the elastic composite structure can be optimized by changing its dimensions and arrangement, including size, number, and rotation angle of square inclusions. The simulation results show that increasing the number of inclusions and the filling fraction of the unit cell significantly broaden the phononic bandgap compared to other geometric tunings. Additionally, a nonmonotonic relationship between the bandwidth and filling fraction of the composite was found, and this relationship results from spacing among inclusions and inclusion sizes causing different effects on Bragg scatterings and localized resonances of elastic waves. Moreover, the calculated transmission spectra of the epoxy/tungsten carbide composite structure verify its low-frequency bandgap behavior.

A waveform inversion technique for measuring elastic wave attenuation in cylindrical bars

Geophysics ◽  
1992 ◽  
Vol 57 (6) ◽  
pp. 854-859 ◽  
Author(s):  
Xiao Ming Tang
Keyword(s):  
Elastic Wave ◽  
Wave Attenuation ◽  
Waveform Inversion ◽  
Finite Size ◽  
Low Frequency ◽  
Frequency Range ◽  
Multiple Reflections ◽  
Low Frequencies ◽  
The Time Domain ◽  
Attenuation Values

A new technique for measuring elastic wave attenuation in the frequency range of 10–150 kHz consists of measuring low‐frequency waveforms using two cylindrical bars of the same material but of different lengths. The attenuation is obtained through two steps. In the first, the waveform measured within the shorter bar is propagated to the length of the longer bar, and the distortion of the waveform due to the dispersion effect of the cylindrical waveguide is compensated. The second step is the inversion for the attenuation or Q of the bar material by minimizing the difference between the waveform propagated from the shorter bar and the waveform measured within the longer bar. The waveform inversion is performed in the time domain, and the waveforms can be appropriately truncated to avoid multiple reflections due to the finite size of the (shorter) sample, allowing attenuation to be measured at long wavelengths or low frequencies. The frequency range in which this technique operates fills the gap between the resonant bar measurement (∼10 kHz) and ultrasonic measurement (∼100–1000 kHz). By using the technique, attenuation values in a PVC (a highly attenuative) material and in Sierra White granite were measured in the frequency range of 40–140 kHz. The obtained attenuation values for the two materials are found to be reliable and consistent.

Elastic wave propagation in metamaterial rods with periodic shunted piezo-patches

2021 ◽  
Vol 263 (2) ◽  
pp. 4303-4311
Author(s):  
Edson J.P. de Miranda ◽  
Edilson D. Nobrega ◽  
Leopoldo P.R. de Oliveira ◽  
José M.C. Dos Santos
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Wave Attenuation ◽  
Periodic Structures ◽  
Band Gaps ◽  
Low Frequencies ◽  
Periodic Arrays ◽  
Extended Plane ◽  
Elastic Metamaterials ◽  
Piezoelectric Structures

The wave propagation attenuation in low frequencies by using piezoelectric elastic metamaterials has been developed in recent years. These piezoelectric structures exhibit abnormal properties, different from those found in nature, through the artificial design of the topology or exploring the shunt circuit parameters. In this study, the wave propagation in a 1-D elastic metamaterial rod with periodic arrays of shunted piezo-patches is investigated. This piezoelectric metamaterial rod is capable of filtering the propagation of longitudinal elastic waves over a specified range of frequency, called band gaps. The complex dispersion diagrams are obtained by the extended plane wave expansion (EPWE) and wave finite element (WFE) approaches. The comparison between these methods shows good agreement. The Bragg-type and locally resonant band gaps are opened up. The shunt circuits influence significantly the propagating and the evanescent modes. The results can be used for elastic wave attenuation using piezoelectric periodic structures.

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