Physical modeling of anisotropic domains: Ultrasonic imaging of laser-etched fractures in glass

Stewart, Robert R.; Dyaur, Nikolay; Omoboya, Bode; Figueiredo, José J. S. de; Willis, Mark E.; Sil, Samik

doi:10.1190/geo2012-0075.1

Cited by 42 publications

(5 citation statements)

References 15 publications

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“…The ultrasonic pulse-transmission technique is often used to find the velocity and attenuation values of geologic materials, especially for measurements of a jacketed sample in a pressure vessel (Mavko & Nolen-Hoeksema, 1994;Stewart et al, 2012;Toksöz et al, 1979;Vernik & Liu, 1997). In this study, we use Panametrics longitudinal (V114) and shear (V153) transducers for P-and S-wave experiments.…”

Section: Ultrasonic Pulse-transmission Methodsmentioning

confidence: 99%

Attenuation of Rock Salt: Ultrasonic Lab Analysis of Gulf of Mexico Coastal Samples

2020

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In an effort to achieve higher‐resolution imaging as well as detailed lithology descriptions, it is important to consider attenuation as an aid in compensating for seismic wave amplitude and phase distortions due to the viscoelastic properties of natural rocks. We have evaluated elastic‐wave attenuation on a variety of Gulf of Mexico (GoM) rock salt samples (>95% halite by weight) in the laboratory using the ultrasonic pulse‐transmission technique and the spectral ratio (SR) method. Under conditions of 297 K (75°F) and relative humidity of 46%, the estimated P‐ and S‐wave quality factors QP and QS range from 26 to 74 and 29 to 44 in the unjacketed core samples, respectively. Increasing triaxial pressure elevates Q (decreases attenuation), possibly due to the crack closure and rock frame compaction. For example, a 40 MPa confining pressure increases QP to 275 at 297 K (75°F). Elevating temperature does not show a significant effect on Q values until raised from 339 to 366 K (150°F to 200°F), during which QP drops sharply (attenuation increases). The attenuation mechanisms may include thermal cracking and grain boundary condition changes. We have determined well‐constrained empirical relationships between Q and velocity (V) for both P‐ and S‐waves. These measurements and empirical relationships can further inform us about salt properties and assist with images of and through salt bodies.

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Section: Ultrasonic Pulse-transmission Methodsmentioning

confidence: 99%

Attenuation of Rock Salt: Ultrasonic Lab Analysis of Gulf of Mexico Coastal Samples

2020

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“…But even nowadays, physical modeling is still frequently used for configurations whose response is difficult to model numerically. It has been used to study wave propagation in complex 3D media, such as anisotropic (Stewart et al, 2013), random heterogeneous (Sivaji et al, 2002), dynamic (Sherlock and Evans, 2001), fractured (Ekanem et al, 2013), or anelastic (Lines et al, 2012) media. Data from laboratory experiments are considered as input data in inverse problems (Pratt, 1999), for testing new data processing algorithms (Campman et al, 2005), in time-lapse 3D studies (Sherlock et al, 2000), and to benchmark numerical model solutions (Bretaudeau et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of 3D zero-offset laboratory data by a discretized Kirchhoff integral method

et al. 2014

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International audienceAccurate simulation of seismic wave propagation in complex geologic structures is of particular interest nowadays. However, difficulties arise for complex geologic structures with great and rapid structural changes, due, for instance, to the presence of shadow zones, head waves, diffractions and/or edge effects. Different methods have thus been developed and are typically tested on synthetic configurations against analytical solutions for simple canonical problems, reference methods, or via direct comparison with real data acquired in situ. Such approaches have limitations, especially if the propagation occurs in a complex environment with strong-contrast reflectors and surface irregularities because it can be difficult to determine the method that gives the best approximation of the "real" solution or to interpret the results obtained without an a priori knowledge of the geologic environment. An alternative approach for seismics consists in comparing the synthetic data with data obtained in laboratory experiments. In contrast to in situ experiments, high-quality data are collected under controlled conditions for a known configuration. In contrast with numerical experiments, laboratory data possess many of the characteristics of field data because real waves propagate through models with no numerical approximations. Our main purpose was to test the approach of using laboratory data as reference data for benchmarking 3D numerical methods and techniques using the setup that we have designed for this study. We performed laboratory-scaled measurements of zero-offset reflection of broadband pulses from a strong topographic environment immersed in a water tank. We compared these measurements with numerical data simulated by means of a discretized Kirchhoff integral method. The comparisons of synthetic and laboratory data indicated a good quantitative fit in terms of time arrivals and acceptable fit in amplitudes. Thus, the first step of the approach was successfully applied

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“…The construction of the anisotropic cracked sample as well as the ultrasonic measurements was carried out at the Allied Geophysical Laboratories (AGL) at the University of Houston, Texas. The experimental setup used to make the samples and carry out the S-waveform measurements was the same as used in Omoboya et al (2011), de Figueiredo et al (2012, Stewart et al (2013), andde Figueiredo et al (2013). It is described in detail in these works.…”

Section: Methodsmentioning

confidence: 99%

On the source-frequency dependence of fracture-orientation estimates from shearwave transmission experiments

Santos¹,

Figueiredo²,

Omoboya³

et al. 2014

Proceedings of the 6 Simpósio Brasileiro De Geofísica

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Shear-wave propagation through anisotropic fractured or cracked media can provide valuable information about these fracture swarms and their orientations. The main goal of this work is to recover information about fracture orientation based on the shear waveforms (Swaveforms). For this study, we carried out ultrasonic Swave measurements in a synthetic physical model made of epoxy resin (isotropic matrix proxy), with small rubber strips as inclusions (artificial cracks) inserted in it to simulate a homogeneous anisotropic medium. In these experiments, we used low, intermediate, and high frequency shear-wave sources, with frequencies 90, 431, and 840 kHz. We integrated and interpreted the resulting S-wave seismograms, cross-correlation panels and anisotropic parameter-analysis curves. We were able to estimate the crack orientation in singleorientation fracture zones. We applied a bandpass filtering process to the intermediate and high frequencies seismograms in order to obtain low frequency seismograms. A spectral analysis using frequency-wavenumber (F-K) spectra supports this filtering process. The results obtained using an analysis of cross-correlograms and the Thomsen parameter extracted from filtered high-frequency data were quite similar to those obtained using a low-frequency source. This highlighted the possibility of using less expensive high-frequency sources to recover information about the fracture set.

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Physical modeling of anisotropic domains: Ultrasonic imaging of laser-etched fractures in glass

Cited by 42 publications

References 15 publications

Attenuation of Rock Salt: Ultrasonic Lab Analysis of Gulf of Mexico Coastal Samples

Attenuation of Rock Salt: Ultrasonic Lab Analysis of Gulf of Mexico Coastal Samples

Numerical modeling of 3D zero-offset laboratory data by a discretized Kirchhoff integral method

On the source-frequency dependence of fracture-orientation estimates from shearwave transmission experiments

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