Fracture detection in crystalline rocks using ultrasonic reflection techniques

Palmer, Selwyn; Smith, James A.; Waters, K. H.

doi:10.1016/0148-9062(81)90004-8

Cited by 5 publications

(8 citation statements)

References 5 publications

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“…We first present a numerical modeling example considering an ultrasonic laboratory experiment to characterize a single horizontal fracture (Figure 1a). A horizontal receiver array measures the reflected waves due to sources located at the same level as the receiver array (e.g., Palmer et al, 1981). Note that this configuration is equivalent to a vertical receiver array recording reflected waves from a vertical fracture (e.g., Cheng and Sansalone, 1995).…”

Section: Model and Datamentioning

confidence: 99%

Elastic least-squares migration for quantitative reflection imaging of fracture compliances

2020

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To quantitatively image fractures with high resolution, we develop an elastic least-squares migration (LSM) algorithm coupled with linear-slip theory, which accurately addresses seismic wave interaction with thin structures. We derive a linearized waveform inversion using the Born approximation to the boundary integral equation for scattered waves, including linear-slip interfaces for P-SV and SH wavefields. Numerical modeling tests assuming a laboratory-scale fracture where a 20 cm long fracture is illuminated by waves with 50 KHz center frequency, show that the proposed LSM successfully estimates the fracture compliances. Furthermore, due to the presence of coupling compliances at the fracture, the results using the proposed LSM show better images than those using the conventional LSM estimating Lamé constants. We also numerically illustrate that the proposed LSM can be successfully applied to dipole acoustic borehole logging data with 3 KHz center frequency for single-well reflection imaging of a 10 m long, dipping fracture embedded in a random background. Finally, we apply the LSM to laboratory experimental data, measuring PP reflections from a fluid-filled fracture. We confirm that the estimated fracture compliances correspond well to those estimated by earlier AVO inversion. Furthermore, the LSM resolves the spatially varying fracture compliances due to local filling of water in the fracture. Because the linear-slip theory can be applied to thin structures in a wide range of scales, high-resolution imaging results and estimated fracture compliance distributions will be crucial to further address small-scale properties at fractures, joints and geological faults.

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Section: Model and Datamentioning

confidence: 99%

Elastic least-squares migration for quantitative reflection imaging of fracture compliances

2020

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“…In order to verify the capability of the ultrasonic transducers (and the ultrasonic system as a whole) to acquire the reflected signals independent of any potential "ringing" effects (Palmer et al, 1981), an aluminum (Al) specimen with dimensions exactly identical to the SG specimens was tested (also see Figure 2. Comparison of the percent failure stress-axial strain plots obtained from the LVDT and the 2-D DIC measurements, respectively, for the three specimens.…”

Section: Lut Setup and Signal Analysismentioning

confidence: 99%

“…Another issue which impedes the practical (field‐based) application of T‐mode‐based LUT evaluation of damage is that it can only be performed when two sides of a material are accessible (Trtnik et al, 2013). To overcome these shortcomings of the T‐mode LUT approach, the R‐mode LUT approach was proposed for ultrasonic material evaluation (Palmer et al, 1981). The R‐mode LUT approach relies on the reflected signals from interfaces (features like cracks and material boundaries) encountered in a medium.…”

Section: Introductionmentioning

confidence: 99%

“…Hedayat (2013) and Hedayat & Walton (2017) noted that the reflected ultrasonic signals are capable of detecting damage in the joint interface prior to failure. Palmer et al (1981) used R‐mode LUT for evaluating the sensitivity of the reflected signals in detecting damage in an intact granite slab (0.9 × 0.9 × 0.3 m), in which the fractures were artificially induced. This study showed that R‐mode LUT can efficiently facilitate fracture detection at the laboratory‐scale and recommended that it should also be utilized at the field scale.…”

Section: Introductionmentioning

confidence: 99%

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Illumination of Damage in Intact Rocks by Ultrasonic Transmission‐Reflection and Digital Image Correlation

2020

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Laboratory‐scale experiments on intact rocks are critical to the development of physics‐based fundamental understanding of various geophysical phenomena. In this work, the capability of ultrasonic wave transmission (T‐mode) and reflection (R‐mode) to monitor damage progression in uniaxially loaded prismatic intact rock specimens has been analyzed, as it is imperative to study the observations and document the capabilities of these techniques in a controlled environment. This study is novel in the sense that the R‐mode linear ultrasonic testing (LUT) has been rarely employed in studying intact rock damage processes in a laboratory setting, with most of the studies utilizing a direct transmission (T‐mode) approach or focusing on macroscopically fractured material. The two‐dimensional digital image correlation (2‐D DIC) full‐field strain measurement approach was also used in‐sync with the LUT monitoring to explicitly correlate the stress‐induced damage in the specimens with the changes observed in the ultrasonic (T‐mode and R‐mode) signals. The results show that both the T‐mode and R‐mode LUT approaches are sensitive to detect the evolution of tensile and shear damage in the specimens, with the R‐mode ultrasonic signals showing higher degree of sensitivity to the damage in the rocks, immediately following the initiation of damage in the rock volume.

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“…Sur l'enregistrement déroulé, les fractures s'individualisent comme des traces sinusoïdales noires témoignant d'une forte rugosité, ou d'une ouverture libre (BHTV), ou encore d'une forte conductivité (FMS). Les essais d'application de méthodes géophysiques à la mesure des fractures sont nombreux (Palmer et al, 1981 ;Mikhailov et al, 2000) mais leur efficacité est limitée en général aux fractures conductrices d'eau ou d'huile. En particulier, les fractures disposées en paquets ne sont pas distinguées individuellement par ces outils (Genter et al, 1997).…”

Section: Les Techniques De Diagraphieunclassified

Étude comparée de la fracturation observable sur carottes de forage et obtenue par diagraphie. Application au marbre de Saint-Béat (31)

Gasc‐Barbier

Fouché

Gaillard³

2010

Rev. Fr. Geotech.

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Étude comparée de la fracturation observable sur carottes de forage et obtenue par diagraphie. Application au marbre de Saint-Béat (31) Résumé L'analyse structurale d'un massif rocheux dans le cadre d'un projet de tunnel passe dans la majorité des cas par une analyse des discontinuités présentes grâce à l'imagerie de paroi. Cette méthode de reconnaissance est combinée à d'autres techniques pour reconnaître l'ensemble des caractéristiques du massif. Cette technique, très utile, présente néanmoins des limites d'application qu'il convient de prendre en compte. Pour illustrer notre propos, nous nous sommes appuyés sur le cas des reconnaissances menées pour le tunnel de Saint-Béat, en comparant les discontinuités relevées sur imagerie numérique de paroi et manuellement sur carottes. Nous avons mis en avant les biais induits par ces méthodes, biais qu'il convient de prendre en compte pour mieux caractériser la géométrie du réseau de fractures considéré. Mots-clés : imagerie de paroi, carottes, densité de fracturation, marbre.

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Fracture detection in crystalline rocks using ultrasonic reflection techniques

Cited by 5 publications

References 5 publications

Elastic least-squares migration for quantitative reflection imaging of fracture compliances

Elastic least-squares migration for quantitative reflection imaging of fracture compliances

Illumination of Damage in Intact Rocks by Ultrasonic Transmission‐Reflection and Digital Image Correlation

Étude comparée de la fracturation observable sur carottes de forage et obtenue par diagraphie. Application au marbre de Saint-Béat (31)

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