An inversion for Biot parameters in water-saturated sand

Chotiros, Nicholas P.

doi:10.1121/1.1511199

Cited by 36 publications

(23 citation statements)

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“…A Z E of zero is used in the body of this report. Pressure coefficients computed using Johnson and Plona's method [20] are calculated below and compared to pressure coefficients from the lumped parameter method, (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), are calculated and compared to modes shapes from the lumped parameter method, eqs. and .…”

Section: Discussionmentioning

confidence: 99%

“…K s is 9 standard deviations lower than the recognized value for sand modulus (about 36 GPa [32]). It is interesting that Chotiros [13] also calculated a sand modulus of K s = 7 GPa using a numerical inversion technique from measured parameters (he concluded 7 GPa was low). The formulas for the generalized moduli, eqs.…”

Section: Modulimentioning

confidence: 99%

“…The fast and slow effective density numbers in eq. (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) are at 250 kHz. As can been seen, the density of the fast wave is 89% + 3% of the total density.…”

Section: In Eq (4-11) M S (W)mentioning

confidence: 99%

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Experimental Study of Sound Waves in Sandy Sediment

Yargus¹

2003

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and have found that it is complete and satisfactory in all respects, and that any and all revisions required by the final examining committee have been made. This dissertation describes experiments intended to help understand the physics of sound (compressional waves) propagating through sandy sediments (unconsolidated porous media). The theory (using a lumped parameter model) and measurements (using a reflection ratio technique) includes derivations and measurements of acoustic impedances, effective densities, wave speeds (phase velocities), effective pressures, mode shapes, pressure reflection coefficients, and material moduli. The results show the acoustic impedance divided by the phase velocity, rendering an "effective density," is less than the total density of the sediment (effective density = 89% + 3% of total). The results also show the fluid in the sediment oscillates back-and-forth 2.2 + 0.4 times farther than the sand in the sediment (mode shape) during the passing of a sound wave.These facts suggest the existence of Biot waves (two compressional waves) in watersaturated sand.

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Section: Discussionmentioning

confidence: 99%

Section: Modulimentioning

confidence: 99%

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Experimental Study of Sound Waves in Sandy Sediment

Yargus¹

2003

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“…The model involves more parameters than the elastic case, but on the other hand, the wave velocities, attenuation and dispersion characteristics are computed from the medium's intrinsic properties without resorting to empirical relationships. However, the inverse problem has only been rarely addressed (Chotiros, 2002;Berryman et al, 2002) despite the fact that it can provide useful information on the material properties, especially the permeability and porosity, from the seismic waveforms and attenuation. The aim of this study is to extend the methodology used in the elastic case (Dietrich and Kormendi, 1990) to derive the Fréchet derivatives for stratified poro-elastic media.…”

Section: Introductionmentioning

confidence: 99%

First‐order perturbations of the seismic response of fluid‐filled stratified poro‐elastic media

Barros

Dietrich

2006

SEG Technical Program Expanded Abstracts 2006

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SUMMARYWe derive analytical formulas for the first-order effects produced by plane inhomogeneities on the seismic response of a stratified porous medium. The approach used for the derivation is similar to the one employed in the elastic case; it is based on a perturbation analysis of the poro-elastic wave propagation equations. The final forms of the sensitivity operators, which are often referred to as the Fréchet derivatives, are expressed in terms of the Green's functions of the solid and fluid displacements in the frequency-ray parameter domain. We compute here the Fréchet derivatives with respect to eight parameters, namely, the fluid and mineral density and bulk moduli, porosity, permeability, consolidation parameter and shear modulus. The accuracy and stability of the derived expressions are checked by comparing differential seismograms computed from the analytical expressions of the Fréchet derivatives with solutions obtained by introducing discrete perturbations into the model properties. We find that the Fréchet derivative approach is generally accurate for perturbations of the medium properties of up to 10%, and for layer thicknesses less than one fifth of the dominant wavelength.

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“…The BiotStoll poro-elastic model [30] depends on a large number of parameters to predict the seismoacoustic response of a particular sediment [1,22]. Chotiros [5] developed an extended Biot model and obtained an inversion for Biot parameters in saturated sand. Briggs [8] obtained empirical relationships relating sediment sound speed, attenuation, and density to sediment properties and composition.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Seismoacoustic Properties of Marine Sediments

Chamuel¹

2003

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REPORT DOCUMENTATION PAGE Form Approved 0MB No. 0704-0188Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing Instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the colleaion of information. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)Office of %x^el?nfen?afTri'ffii? §^'*Sf^^^presented on fundamental seismoacoustic characteristics of unconsolidated sediments not explained by existing theories. Precision measurements of the compressional velocity "Cp" in coarse water-saturated sand revealed that Cp decreased hy 14% as frequency increased from 80 to 880 kHz, while the Biot theory predicted an increase of < 1 %. Measured dispersion in saturated fine sand and glass beads had a similar trend. Data from Kings Bay Experiment by Chotiros (1995) were replotted indicating that Cp decreased by 6% as frequency increased from 5 to 60 kHz. Cp in drained sand and glass beads remained near the saturated value 1750m/s in contrast with the 85% decrease predicted by the low-fi-equency Biot-Gassman theory. Time-dependent stiffening was detected in drained sediments. Visualization of capillary mechanisms using seawater and glass microplates provided physical insight into grain to grain coupling and time-dependent properties. Unique features were observed on crystallization in confined geometry, solid-like behavior of confined seawater, cavitation, and shear coupling. Capillary experiments on gassy sediments showed that when air was injected in water-saturated sand, oblique 45° fracture cracks formed in the sand as it became locally unsaturated. The cracks were perpendicular to each other originating from the air source location. SUBJECT TERMS ABSTRACTExperimental findings are presented on fundamental seismoacoustic characteristics of unconsolidated sediments not explained by existing theories. Precision measurements of the compressional velocity "Cp" in coarse water-saturated sand revealed that Cp decreased by 14% as frequency increased from 80 to 880 kHz, while the Biot theory predicted an increase of < 1 %. Measured dispersion in saturated fine sand and glass beads had a similar trend. Data from Kings Bay Experiment by Chotiros (1995) were replotted indicating that Cp decreased by 6% as frequency increased from 5 to 60 kHz. Cp in drained sand and glass beads remained near the saturated value (1750 m/s) in contrast with the 85% decrease predicted by the low-frequency Biot-Gassman theory. Timedependent stiffening was detected in drained sediments. Visualization of capillary mechanisms using seawater and glass microplates provided physical insight into grain to grain coupling and time-dependent properties. Unique features were observed on crystallization in confined geometry, solid-like behavior of confined seawater, cavitation, and shear coupling. Capillary experiments on gassy sediments showed that when air was injected in water-saturated sand, oblique 45° fracture cracks...

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An inversion for Biot parameters in water-saturated sand

Cited by 36 publications

References 22 publications

Experimental Study of Sound Waves in Sandy Sediment

Experimental Study of Sound Waves in Sandy Sediment

First‐order perturbations of the seismic response of fluid‐filled stratified poro‐elastic media

Characterization of Seismoacoustic Properties of Marine Sediments

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