Laboratory measurement of elastic anisotropy on spherical rock samples by longitudinal and transverse sounding under confining pressure

Lokajı́ček, T.; Svítek, T.

doi:10.1016/j.ultras.2014.08.015

Cited by 35 publications

(17 citation statements)

References 36 publications

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“…With regard to multi‐faced polyhedral, the measurements of Nara et al . () with a 98‐faced sample and of Lokajicek and Svitek () on spherical samples allowing 132 different directions to be sampled are worth noting although these authors have not studied sedimentary rocks. The same spherical apparatus was used by Nadri et al .…”

Section: Introductionmentioning

confidence: 99%

Static and dynamic pressure sensitivity anisotropy of a calcareous shale

Ong

Schmitt

Kofman

et al. 2016

Geophysical Prospecting

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Optimizing the productivity of nonconventional, low‐permeability “shale” reservoirs requires detailed knowledge of the mechanical properties of such materials. These rocks' elastic anisotropy is acknowledged but usually ignored due to difficulties in obtaining such information. Here we study in detail the dynamic and static elastic properties of a suite of calcareous mudstones from the nonconventional Duvernay reservoir of Alberta, Canada. The complete set of transversely isotropic elastic constants is obtained from strategically oriented ultrasonic transducers to confining pressures of 90 MPa. Wave speed anisotropies of up to 35% are observed at even the highest confining pressures. Furthermore, the stress sensitivity of the wave speeds, and hence moduli, is itself highly dependent on direction with speeds taken perpendicular to the bedding plane being highly nonlinearly dependent on pressure, whereas those along the bedding plane show, unexpectedly, nearly no pressure dependence. These observations are in qualitative agreement with the preferentially oriented porosity and minerals seen in scanning electron microscope images. These results may be significant to the interpretation of sonic logs and azimuthal amplitude versus offset for principal stress directions, for the concentration of stress within such formations, and for estimation of static engineering moduli from sonic log wave speeds.

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Section: Introductionmentioning

confidence: 99%

Static and dynamic pressure sensitivity anisotropy of a calcareous shale

Ong

Schmitt

Kofman

et al. 2016

Geophysical Prospecting

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“…For a more detailed description of the measuring procedure, see Lokajíček et al . [] and Lokajíček and Svitek [].…”

Section: Sample Experimental Techniques and Resultsmentioning

confidence: 99%

Seismic anisotropy of serpentinite from Val Malenco, Italy

et al. 2015

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Serpentinites, deformed in mantle subduction zones, are thought to contribute significantly to seismic anisotropy of the upper mantle and have therefore been of great interest with studies on deformation, preferred orientation, and elastic properties. Here we present a combined study of a classical sample from Val Malenco, Italy, investigating the microstructure and texture with state‐of‐the art synchrotron X‐ray and neutron diffraction methods and measuring ultrasonic velocities both with a multi‐anvil apparatus and a novel instrument to measure 3‐D velocities on spheres. Both, results from diffraction methods and velocity measurements are compared, discussing advantages and disadvantages. From spherical velocities, elastic tensor properties can be derived by inversion. Also from quantitative texture measurements, elastic properties can be modeled by self‐consistent averaging. Good agreement between the velocity and microstructural models is observed.

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“…The velocities of elastic P and S waves in spherical samples under a hydrostatic pressure up to 70 MPa were recorded using equipment at the Institute of Geology, Academy of Sciences of the Czech Republic (Prague) [13]. The technique for measuring ultrasonic-wave velocities is based on the application of ultrasonic transducers for transmitting and receiving elastic pulses, a system of step-by-step two-coordinate sample rotation, and the corresponding environment (high-pressure chamber).…”

Section: Experimental Techniquesmentioning

confidence: 99%

“…Thus, 25 measurements are performed for each λ value. Passing through all points in a specified way, (7) highly viscous gel layer [13]. …”

Section: Experimental Techniquesmentioning

confidence: 99%

“…Initially, the velocities of longitudinal P waves were recorded on spherical samples in 132 independent directions under different hydrostatic pressures up to 600 MPa. After modification, the system included two additional pairs of transducers for measuring transverse S waves on the same directional network but at a lower hydrostatic pressure [13].…”

Section: Introductionmentioning

confidence: 99%

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Application of a modified method of ultrasonic measurements for determination of elastic moduli of rocks

et al. 2015

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The velocities of elastic waves with quasi-longitudinal and quasi-transverse polarizations in a spherical rock sample have been measured. The experimental values of velocities are used to calculate 21 elastic moduli of the sample. For comparison, the effective elastic properties of the sample are simulated based on the data on the crystallographic textures of rock-forming minerals obtained by neutron diffraction. It is shown that the largest discrepancy between the model predictions and experimental velocity values is observed for transversely polarized waves.

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Laboratory measurement of elastic anisotropy on spherical rock samples by longitudinal and transverse sounding under confining pressure

Cited by 35 publications

References 36 publications

Static and dynamic pressure sensitivity anisotropy of a calcareous shale

Static and dynamic pressure sensitivity anisotropy of a calcareous shale

Seismic anisotropy of serpentinite from Val Malenco, Italy

Application of a modified method of ultrasonic measurements for determination of elastic moduli of rocks

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