Comparison of experimental velocity measurements with theoretical results in a solid‐solid composite material

Zhang, Mei; Ebrom, Dan; McDonald, John A.; Tatham, Robert H.

doi:10.1190/1.1444068

Cited by 8 publications

(3 citation statements)

References 10 publications

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“…As long as compositional heterogeneity exists, the thin section may not be an accurate representation of the rock sample. As the uncertainties discussed above are difficult to avoid in the case of natural samples, comparisons between calculated and observed values in hot‐pressed, porosity‐free, isotropic multiphase composites with well controlled chemical compositions and volume fractions for each phase may be preferable for testing the mixing rules [ Watt et al , 1976; Zhang et al , 1996; Ji and Wang , 1999]. Much work remains to be done in this area to yield better constraints on the interpretation of seismic data.…”

Section: Discussionmentioning

confidence: 99%

Seismic velocities and anisotropy of core samples from the Chinese Continental Scientific Drilling borehole in the Sulu UHP terrane, eastern China

Sun¹,

Ji²,

Wang³

et al. 2012

J. Geophys. Res.

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[1] A detailed study of seismic properties (P and S wave velocities, hysteresis, anisotropy and shear wave splitting) has been carried out on a unique suite of deep borehole core samples from the Chinese Continental Scientific Drilling (CCSD) project, which penetrated 5158 m into the Sulu ultrahigh-pressure (UHP) metamorphic terrane (China). Seismic velocities of the deep core samples are more and less sensitive to pressure in the low pressure (<200-300 MPa) nonlinear and high pressure (>200-300 MPa) linear regimes, respectively, than samples from the surface. The comparison suggests that the high pressure data from the core samples are much more reliable for extrapolation to deeper crust than the data from surface analogs that have been subjected to long histories of weathering and alteration along intergranular and transgranular cracks. The significant increases in the pressure sensitivity of seismic velocities for the core samples in the nonlinear regime indicate that drilling-induced and stress-relief microcracks with small aspect ratios are fresh and clean without secondary mineral in-fillings, and are thus easy to close completely under the applied hydrostatic pressure conditions of the laboratory. The data also elucidate that the velocity-pressure data can successfully provide important hints about the preferred orientation of microcracks that causes P wave velocity anisotropy and shear wave splitting in cracked rocks, and that the effect of compression on the V p /V s ratios is negligible for crack-free compacted rocks. The seismic velocities of equivalent isotropic (fabric-free) and crack-free crystalline aggregates calculated from room pressure single crystal elastic constants using the Voigt average are in good agreement with the laboratory data at $200 MPa. Comparison of the seismic reflection image from the vicinity of the borehole with the normal-incidence reflection coefficient profile computed from the laboratory-measured velocities and densities infers that the seismic reflections originate from mafic (eclogite and retrograde eclogite) or ultramafic units within dominantly felsic rocks.

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Section: Discussionmentioning

confidence: 99%

Seismic velocities and anisotropy of core samples from the Chinese Continental Scientific Drilling borehole in the Sulu UHP terrane, eastern China

Sun¹,

Ji²,

Wang³

et al. 2012

J. Geophys. Res.

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“…These two composites are of the CPSF type. Left column: laboratory data from Zhang et al (1996). Right column: data from Piche and Hamel (1986).…”

Section: Discussionmentioning

confidence: 99%

DEM and SC estimations of elastic moduli of complex rock matrix using composites as analogs

Ruiz

Dvorkin

2010

SEG Technical Program Expanded Abstracts 2010

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At low porosity, the elastic moduli of the rock mineral matrix often dominates those of the whole rock. A sedimentary rock matrix may be considered as a composite and may include mineral constituents with very different moduli and shapes. To describe the fabric of these rocks, an unmanageable number of parameters may be needed. Understanding the elastic behavior of synthetic composites, which are easier to model, enables us to quantify the effect of each parameter on the elastic moduli of the rock matrix independently. We test whether the differential effectivemedium (DEM) and self-consistent (SC) models can accurately estimate the elastic moduli of a complex rock matrix and compare the results with the average of upper and lower Hashin-Shtrikman bounds (HS). The testing was conducted using data from the literature on composites, covering a wide range of inclusion concentrations, inclusion shapes, and elastic modulus contrasts. We find that when the material microstructure is consistent with the DEM approximation, DEM is more accurate than both SC and the bound-average method for a variety of inclusion aspect ratios, concentrations, and modulus contrasts. If relatively little information is known about the rock microstructure, DEM can estimate the elastic properties of complex mixtures of minerals more accurately than heuristic estimates, such as the arithmetic average of the upper and lower elastic bounds.

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“…This is both an advantage and a disadvantage in that it adds a degree of realism to the model due to natural variation but also that the seismic response of each model is not consistently repeatable. This prompted seismic experiments on samples of grain mixes within consolidated matrices, such as silicon rubber (Purnell, 1986), and resins (Zhang et al, 1996), where grain distribution was more controllable. A fundamental goal of this work, however, was to overcome such problems and move the technology forward.…”

Section: Seismic Physical Modelingmentioning

confidence: 99%

The development of seismic reflection sandbox modeling

Sherlock

Evans

2001

Bulletin

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Analog sandbox models provide cheap, concise data and allow the evolution of geological structures to be observed under controlled laboratory conditions. Seismic physical modeling is used to study the effects of seismic wave propagation in isotropic and anisotropic media, and to improve methods of data acquisition, processing, and interpretation. By combining these two independent modeling techniques, the potential exists to expand the benefits of each method. For seismic physical modeling, the main advantages are that the seismic data collected from these models contain natural variations that cannot be built into conventional solid models, which are machined with predetermined structures. In addition, the cost and construction time to build these models is significantly reduced. For sandbox modeling, the ability to record threedimensional (3-D) seismic images before the model is manually sectioned for conventional two-dimensional (2-D) structural interpretation allows far more detailed study of subtle 3-D structures than previously possible. In the past other workers have attempted to use unconsolidated sands for seismic physical models, but these attempts have been unsuccessful because of the lack of control or understanding of the natural variations that occur throughout the models. The aim of our research has been to overcome such problems and to develop techniques to alter the acoustic impedance of sand layers, thereby allowing the subsequent ultrasonic seismic recording of 3-D fault systems in sand analog geological models.

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Comparison of experimental velocity measurements with theoretical results in a solid‐solid composite material

Cited by 8 publications

References 10 publications

Seismic velocities and anisotropy of core samples from the Chinese Continental Scientific Drilling borehole in the Sulu UHP terrane, eastern China

Seismic velocities and anisotropy of core samples from the Chinese Continental Scientific Drilling borehole in the Sulu UHP terrane, eastern China

DEM and SC estimations of elastic moduli of complex rock matrix using composites as analogs

The development of seismic reflection sandbox modeling

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