Laboratory measurements of ultrasonic P-wave and S-wave attenuation during the freezing of salty water in porous material

In this paper, a modification of an existing method for estimating relative P-wave attenuation is proposed. By generating synthetic waveforms without attenuation, the variation of geometrical spreading related to changes in formation properties with depth can be accounted for. With the modified method, reliable P- and S-wave attenuation logs can be extracted from monopole array acoustic waveform log data. Synthetic tests show that the P- and S-wave attenuation values estimated from synthetic waveforms agree well with their respective model values. In‐situ P- and S-wave attenuation profiles provide valuable information about reservoir rock properties. Field data processing results show that this method gives robust estimates of intrinsic attenuation. The attenuation profiles calculated independently from each waveform of an eight‐receiver array are consistent with one another. In fast formations where S-wave velocity exceeds the borehole fluid velocity, both P-wave attenuation ([Formula: see text]) and S-wave attenuation ([Formula: see text]) profiles can be obtained. P- and S-wave attenuation profiles and their comparisons are presented for three reservoirs. Their correlations with formation lithology, permeability, and fractures are also presented.

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A method of geo-acoustic parameter inversion in shallow sea by the Bayesian theory and the acoustic pressure field

MATEC Web of Conferences ◽

10.1051/matecconf/201928306003 ◽

2019 ◽

Vol 283 ◽

pp. 06003

Author(s):

Guangxue Zheng ◽

Hanhao Zhu ◽

Jun Zhu

Keyword(s):

Sound Pressure ◽

Pressure Field ◽

Wave Attenuation ◽

Acoustic Parameter ◽

Bayesian Theory ◽

P Wave ◽

Shallow Sea ◽

S Wave ◽

Wave Velocities ◽

Parameter Inversion

A method of geo-acoustic parameter inversion based on the Bayesian theory is proposed for the acquisition of acoustic parameters in shallow sea with the elastic seabed. Firstly, the theoretical prediction value of the sound pressure field is calculated by the fast field method (FFM). According to the Bayesian theory, we establish the misfit function between the measured sound pressure field and the theoretical pressure field. It is under the assumption of Gaussian data errors which are in line with the likelihood function. Finally, the posterior probability density (PPD) of parameters is given as the result of inversion. Our research is conducted in the light of Metropolis sample rules. Apart from numerical simulations, a scaled model experiment has been taken in the laboratory tank. The results of numerical simulations and tank experiments show that sound pressure field calculated by the result of inversion is consistent with the measured sound pressure field. Besides, s-wave velocities, p-wave velocities and seafloor density have fewer uncertainties and are more sensitive to complex sound pressure than s-wave attenuation and p-wave attenuation. The received signals calculated by inversion results are keeping with received signals in the experiment which verify the effectiveness of this method.

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Rock-physics modeling of ultrasonic P- and S-wave attenuation in partially frozen brine and unconsolidated sand systems and comparison with laboratory measurements

Geophysics ◽

10.1190/geo2018-0408.1 ◽

2019 ◽

Vol 84 (5) ◽

pp. MR153-MR171 ◽

Cited By ~ 1

Author(s):

Linsen Zhan ◽

Jun Matsushima

Keyword(s):

Ultrasonic Wave ◽

Wave Attenuation ◽

Freezing Point ◽

Rock Physics ◽

Ultrasonic Waves ◽

P Wave ◽

Dominant Factor ◽

S Wave ◽

High Attenuation ◽

Unconsolidated Sand

The nonintuitive observation of the simultaneous high velocity and high attenuation of ultrasonic waves near the freezing point of brine was previously measured in partially frozen systems. However, previous studies could not fully elucidate the attenuation variation of ultrasonic wave propagation in a partially frozen system. We have investigated the potential attenuation mechanisms responsible for previously obtained laboratory results by modeling ultrasonic wave transmission in two different partially frozen systems: partially frozen brine (two phases composed of ice and unfrozen brine) and unconsolidated sand (three phases composed of ice, unfrozen brine, and sand). We adopted two different rock-physics models: an effective medium model for partially frozen brine and a three-phase extension of the Biot model for partially frozen unconsolidated sand. For partially frozen brine, our rock-physics study indicated that squirt flow caused by unfrozen brine inclusions in porous ice could be responsible for high P-wave attenuation around the freezing point. Decreasing P-wave attenuation below the freezing point can be explained by the gradual decrease of squirt flow due to the gradual depletion of unfrozen brine. For partially frozen unconsolidated sand, our rock-physics study implied that squirt flow between ice grains is a dominant factor for P-wave attenuation around the freezing point. With decreasing temperature lower than the freezing point, the friction between ice and sand grains becomes more dominant for P-wave attenuation because the decreasing amount of unfrozen brine reduces squirt flow between ice grains, whereas the generation of ice increases the friction. The increasing friction between ice and sand grains caused by ice formation is possibly responsible for increasing the S-wave attenuation at decreasing temperatures. Then, further generation of ice with further cooling reduces the elastic contrast between ice and sand grains, hindering their relative motion; thus, reducing the P- and S-wave attenuation.

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P-wave attenuation measurements from laboratory resonance and sonic waveform data

Geophysics ◽

10.1190/1.1442579 ◽

1989 ◽

Vol 54 (1) ◽

pp. 76-81 ◽

Cited By ~ 12

Author(s):

D. Goldberg ◽

B. Zinszner

Keyword(s):

Wave Attenuation ◽

Compressional Wave ◽

P Wave ◽

Laboratory Measurements ◽

Frequency Range ◽

Waveform Data ◽

Sonic Log ◽

In Situ Conditions ◽

The Mean

We computed compressional‐wave velocity [Formula: see text] and attenuation [Formula: see text] from sonic log waveforms recorded in a cored, 30 m thick, dolostone reservoir; using cores from the same reservoir, laboratory measurements of [Formula: see text] and [Formula: see text] were also obtained. We used a resonant bar technique to measure extensional and shear‐wave velocities and attenuations in the laboratory, so that the same frequency range as used in sonic logging (5–25 kHz) was studied. Having the same frequency range avoids frequency‐dependent differences between the laboratory and in‐situ measurements. Compressional‐wave attenuations at 0 MPa confining pressure, calculated on 30 samples, gave average [Formula: see text] values of 17. Experimental and geometrical errors were estimated to be about 5 percent. Measurements at elevated effective pressures up to 30 MPa on selected dolostone samples in a homogeneous interval showed mean [Formula: see text] and [Formula: see text] to be approximately equal and consistently greater than 125. At effective stress of 20 MPa and at room temperature, the mean [Formula: see text] over the dolostone interval was 87, a minimum estimate for the approximate in‐situ conditions. We computed compressional‐wave attenuation from sonic log waveforms in the 12.5–25 kHz frequency band using the slope of the spectral ratio of waveforms recorded 0.914 m and 1.524 m from the source. Average [Formula: see text] over the interval was 13.5, and the mean error between this value and the 95 percent confidence interval of the slope was 15.9 percent. The laboratory measurements of [Formula: see text] under elevated pressure conditions were more than five times greater than the mean in‐situ values. This comparison shows that additional extrinsic losses in the log‐derived measurement of [Formula: see text], such as scattering from fine layers and vugs or mode conversion to shear energy dissipating radially from the borehole, dominate the apparent attenuation.

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Laboratory measurements of P-wave and S-wave velocities across a surface analog of the continental crust–mantle boundary: Cabo Ortegal, Spain

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2009.05.032 ◽

2009 ◽

Vol 285 (1-2) ◽

pp. 27-38 ◽

Cited By ~ 22

Author(s):

D. Brown ◽

S. Llana-Funez ◽

R. Carbonell ◽

J. Alvarez-Marron ◽

D. Marti ◽

...

Keyword(s):

Continental Crust ◽

P Wave ◽

Laboratory Measurements ◽

S Wave ◽

Mantle Boundary ◽

Wave Velocities

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Seismic wave attenuation and modulus dispersion in sandstones

Geophysics ◽

10.1190/geo2015-0342.1 ◽

2016 ◽

Vol 81 (3) ◽

pp. D211-D231 ◽

Cited By ~ 39

Author(s):

James W. Spencer ◽

Jacob Shine

Keyword(s):

Wave Attenuation ◽

High Viscosity ◽

P Wave ◽

S Wave ◽

Local Flow ◽

Shear Moduli ◽

Low Viscosity ◽

Confining Pressures ◽

Wave Induced ◽

Dispersion And Attenuation

We have conducted laboratory experiments over the 1–200 Hz band to examine the effects of viscosity and permeability on modulus dispersion and attenuation in sandstones and also to examine the effects of partial gas or oil saturation on velocities and attenuations. Our results have indicated that bulk modulus values with low-viscosity fluids are close to the values predicted using Gassmann’s first equation, but, with increasing frequency and viscosity, the bulk and shear moduli progressively deviate from the values predicted by Gassmann’s equations. The shear moduli increase up to 1 GPa (or approximately 10%) with high-viscosity fluids. The P- and S-wave attenuations ([Formula: see text] and [Formula: see text]) and modulus dispersion with different fluids are indicative of stress relaxations that to the first order are scaling with frequency times viscosity. By fitting Cole-Cole distributions to the scaled modulus and attenuation data, we have found that there are similar P-wave, shear and bulk relaxations, and attenuation peaks in each of the five sandstones studied. The modulus defects range from 11% to 15% in Berea sandstone to 16% to 26% in the other sandstones, but these would be reduced at higher confining pressures. The relaxations shift to lower frequencies as the viscosity increased, but they do not show the dependence on permeability predicted by mesoscopic wave-induced fluid flow (WIFF) theories. Results from other experiments having patchy saturation with liquid [Formula: see text] and high-modulus fluids are consistent with mesoscopic WIFF theories. We have concluded that the modulus dispersion and attenuations ([Formula: see text] and [Formula: see text]) in saturated sandstones are caused by a pore-scale, local-flow mechanism operating near grain contacts.

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Effectiveness of in situ P-wave measurements in monuments: examples from Greece

Journal of Nepal Geological Society ◽

10.3126/jngs.v22i0.32308 ◽

2000 ◽

Vol 22 ◽

Author(s):

B. Christaras

Keyword(s):

Modulus Of Elasticity ◽

Building Stone ◽

P Wave ◽

Mechanical Anisotropy ◽

Laboratory Measurements ◽

S Wave ◽

Wave Velocities ◽

Wave Measurements ◽

Made In

P and S wave velocities can be used for both in situ and laboratory measurements of stones. These methods are used for studying such properties as mechanical anisotropy and modulus of elasticity. In this paper, the P-wave velocities were used for the estimation of the depth of weathered or artificially consolidated layers as well as the depth of cracks developed at the surface of the building stone. This estimation was made in relation to the lithology and texture of the materials, given that in many cases different lithological data create similar diagrams. All tests were carried out on representative monuments in Greece.

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The effects of pore‐fluid salinity on ultrasonic wave propagation in sandstones

Geophysics ◽

10.1190/1.1444404 ◽

1998 ◽

Vol 63 (3) ◽

pp. 928-934 ◽

Cited By ~ 10

Author(s):

Simon M. Jones ◽

Clive McCann ◽

Timothy R. Astin ◽

Jeremy Sothcott

Keyword(s):

Wave Propagation ◽

Ultrasonic Wave ◽

Wave Attenuation ◽

Clay Content ◽

Seismic Wave Propagation ◽

Ultrasonic Pulse ◽

Pore Fluid ◽

P Wave ◽

S Wave ◽

Shear Moduli

Petrophysical interpretation of increasingly refined seismic data from subsurface formations requires a more fundamental understanding of seismic wave propagation in sedimentary rocks. We consider the variation of ultrasonic wave velocity and attenuation in sandstones with pore‐fluid salinity and show that wave propagation is modified in proportion to the clay content of the rock and the salinity of the pore fluid. Using an ultrasonic pulse reflection technique (590–890 kHz), we have measured the P-wave and S-wave velocities and attenuations of 15 saturated sandstones with variable effective pressure (5–60 MPa) and pore‐fluid salinity (0.0–3.4 M). In clean sandstones, there was close agreement between experimental and Biot model values of [Formula: see text], but they diverged progressively in rocks containing more than 5% clay. However, this effect is small: [Formula: see text] changed by only 0.6% per molar change in salinity for a rock with a clay content of 29%. The variation of [Formula: see text] with brine molarity exhibited Biot behavior in some samples but not in others; there was no obvious relationship with clay content. P-wave attenuation was independent of pore‐fluid salinity, while S-wave attenuation was weakly dependent. The velocity data suggest the frame bulk and shear moduli of sandstones are altered by changes in the pore‐fluid salinity. One possible mechanism is the formation damage caused by clay swelling and migration of fines in low‐molarity electrolytes. The absence of variation between the attenuation in water‐saturated and brine‐saturated samples indicates the attenuation mechanism is relatively unaffected by changes in the frame moduli.

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Laboratory measurements of ultrasonic P‐wave attenuation in partially frozen brines by using sweep signals

10.1190/1.3255281 ◽

2009 ◽

Author(s):

Jun Matsushima ◽

Makoto Suzuki ◽

Yoshibumi Kato ◽

Shuichi Rokugawa

Keyword(s):

Wave Attenuation ◽

P Wave ◽

Laboratory Measurements

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