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Title: A Broadband Laboratory Study of the Seismic Properties of Cracked and Fluid-Saturated Synthetic Glass Media

In this paper, for better understanding of frequency dependence (dispersion) of seismic wave velocities caused by stress-induced fluid flow, broadband laboratory measurements were performed on a suite of synthetic glass media containing both equant pores and thermal cracks. Complementary forced oscillation, resonant bar, and ultrasonic techniques provided access to millihertz-hertz frequencies, ~1 kHz frequency, and ~1 MHz frequency, respectively. The wave speeds or effective elastic moduli and associated dissipation were measured on samples under dry, argon- or nitrogen-saturated, and water-saturated conditions in sequence. The elastic moduli, in situ permeability, and crack porosity inferred from in situ X-ray computed tomography all attest to strong pressure-induced crack closure for differential (confining-minus-pore) pressures <30 MPa, consistent with zero-pressure crack aspect ratios <4 × 10 -4. The low permeabilities of these materials allow access to undrained conditions, even at subhertz frequencies. The ultrasonically measured elastic moduli reveal consistently higher shear and bulk moduli upon fluid saturation—diagnostic of the saturated-isolated regime. For a glass rod specimen, containing cracks but no pores, saturated-isolated conditions apparently persist to subhertz frequencies—requiring in situ aspect ratios (minimum/maximum dimension) <10 -5. In marked contrast, the shear modulus measured at subhertz frequencies on a cracked glass bead specimen of 5% porosity,more » is insensitive to fluid saturation, consistent with the Biot-Gassmann model for the saturated-isobaric regime. Finally, the measured dispersion of the shear modulus approaches 10% over the millihertz-megahertz frequency range for the cracked and fluid-saturated media—implying that laboratory ultrasonic data should be used with care in the interpretation of field data.« less
Authors:
 [1] ;  [2] ;  [3] ; ORCiD logo [3] ; ORCiD logo [4] ; ORCiD logo [1]
  1. Australian National Univ., Canberra, ACT (Australia). Research School of Earth Sciences
  2. Australian National Univ., Canberra, ACT (Australia). Research School of Earth Sciences; Univ. College London (United Kingdom). Dept. of Earth Sciences
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Geosciences Division. EESA
  4. Univ. of Alberta, Edmonton, AB (Canada). Dept. of Physics; Purdue Univ., West Lafayette, IN (United States). Earth, Atmospheric, and Planetary Sciences Dept.
Publication Date:
Grant/Contract Number:
AC02-05CH11231; DP110101830
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Solid Earth
Additional Journal Information:
Journal Volume: 123; Journal Issue: 5; Journal ID: ISSN 2169-9313
Publisher:
American Geophysical Union
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Australian National Univ., Canberra, ACT (Australia)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Australian Research Council (ARC)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; seismic properties; broadband measurement; synthetic glass media; dispersion and attenuation
OSTI Identifier:
1471042
Alternate Identifier(s):
OSTI ID: 1437054

Li, Yang, David, Emmanuel C., Nakagawa, Seiji, Kneafsey, Timothy J., Schmitt, Douglas R., and Jackson, Ian. A Broadband Laboratory Study of the Seismic Properties of Cracked and Fluid-Saturated Synthetic Glass Media. United States: N. p., Web. doi:10.1029/2017JB014671.
Li, Yang, David, Emmanuel C., Nakagawa, Seiji, Kneafsey, Timothy J., Schmitt, Douglas R., & Jackson, Ian. A Broadband Laboratory Study of the Seismic Properties of Cracked and Fluid-Saturated Synthetic Glass Media. United States. doi:10.1029/2017JB014671.
Li, Yang, David, Emmanuel C., Nakagawa, Seiji, Kneafsey, Timothy J., Schmitt, Douglas R., and Jackson, Ian. 2018. "A Broadband Laboratory Study of the Seismic Properties of Cracked and Fluid-Saturated Synthetic Glass Media". United States. doi:10.1029/2017JB014671.
@article{osti_1471042,
title = {A Broadband Laboratory Study of the Seismic Properties of Cracked and Fluid-Saturated Synthetic Glass Media},
author = {Li, Yang and David, Emmanuel C. and Nakagawa, Seiji and Kneafsey, Timothy J. and Schmitt, Douglas R. and Jackson, Ian},
abstractNote = {In this paper, for better understanding of frequency dependence (dispersion) of seismic wave velocities caused by stress-induced fluid flow, broadband laboratory measurements were performed on a suite of synthetic glass media containing both equant pores and thermal cracks. Complementary forced oscillation, resonant bar, and ultrasonic techniques provided access to millihertz-hertz frequencies, ~1 kHz frequency, and ~1 MHz frequency, respectively. The wave speeds or effective elastic moduli and associated dissipation were measured on samples under dry, argon- or nitrogen-saturated, and water-saturated conditions in sequence. The elastic moduli, in situ permeability, and crack porosity inferred from in situ X-ray computed tomography all attest to strong pressure-induced crack closure for differential (confining-minus-pore) pressures <30 MPa, consistent with zero-pressure crack aspect ratios <4 × 10-4. The low permeabilities of these materials allow access to undrained conditions, even at subhertz frequencies. The ultrasonically measured elastic moduli reveal consistently higher shear and bulk moduli upon fluid saturation—diagnostic of the saturated-isolated regime. For a glass rod specimen, containing cracks but no pores, saturated-isolated conditions apparently persist to subhertz frequencies—requiring in situ aspect ratios (minimum/maximum dimension) <10-5. In marked contrast, the shear modulus measured at subhertz frequencies on a cracked glass bead specimen of 5% porosity, is insensitive to fluid saturation, consistent with the Biot-Gassmann model for the saturated-isobaric regime. Finally, the measured dispersion of the shear modulus approaches 10% over the millihertz-megahertz frequency range for the cracked and fluid-saturated media—implying that laboratory ultrasonic data should be used with care in the interpretation of field data.},
doi = {10.1029/2017JB014671},
journal = {Journal of Geophysical Research. Solid Earth},
number = 5,
volume = 123,
place = {United States},
year = {2018},
month = {4}
}