The influence of local fluid flow and the microstructure on elastic and anelastic rock properties

Wulff, Angelika-M.; Burkhardt, Hans

doi:10.1007/bf01904048

Cited by 13 publications

(8 citation statements)

References 20 publications

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“…This opens up new avenues for numerical experiments involving more realistic random particle sizes, geometries and properties. Friction (Dobrin 1988), thermal diffusion (Leary 1995) and fluid squirting (Wulff & Burkhardt 1996) have been proposed as causes of wave attenuation. This method may provide an alternative way to investigate these phenomena numerically.…”

Section: Discussionmentioning

confidence: 99%

Numerical simulation of seismic waves using a discrete particle scheme

Toomey

Bean

2000

Geophysical Journal International

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Summary A particle‐based model for the simulation of wave propagation is presented. The model is based on solid‐state physics principles and considers a piece of rock to be a Hookean material composed of discrete particles representing fundamental intact rock units. These particles interact at their contact points and experience reversible elastic forces proportional to their displacement from equilibrium. Particles are followed through space by numerically solving their equations of motion. We demonstrate that a numerical implementation of this scheme is capable of modelling the propagation of elastic waves through heterogeneous isotropic media. The results obtained are compared with a high‐order finite difference solution to the wave equation. The method is found to be accurate, and thus offers an alternative to traditional continuum‐based wave simulators.

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Section: Discussionmentioning

confidence: 99%

Numerical simulation of seismic waves using a discrete particle scheme

Toomey

Bean

2000

Geophysical Journal International

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“…Acoustic compressional ( v p ) and shear ( v s ) wave velocities in approximately 80 vacuum dry and in approximately 50 fully water saturated samples were determined with a pulse transmission technique in the ultrasonic frequency range (0.4–1.0 MHz) [ Wulff and Burkhardt , 1996, 1997; Mayr , 2002; Mayr and Burkhardt , 2006]. Representative samples (homogeneous mineralogy and without visible cracks) were chosen for these measurements.…”

Section: Samples and Methodsmentioning

confidence: 99%

Integrated interpretation of physical properties of rocks of the borehole Yaxcopoil‐1 (Chicxulub impact structure)

et al. 2008

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[1] The borehole Yaxcopoil-1, drilled within the Chicxulub meteoritic impact structure (Mexico), was completely cored from 404 to 1511 m through postimpact Tertiary limestones underlain by impactites. The impactites comprise impact melt-rich, suevitic breccia followed by megablocks of Cretaceous limestones, calcarenites, dolomites, and anhydrites. Measurements of porosity, density, and thermal parameters on 450 samples (equidistant sampling, complete depth range) and of ultrasonic velocities and electric resistivity on 80 representative samples are used to investigate the physical properties of carbonate rocks and to study the influence of the impact. Experiments under elevated pressure, calculations using frequency-dependent Biot-Gassmann theory, and crosschecking with borehole logs, where available, show that ultrasonic laboratory and sonic in situ data correspond. Sonic and electric quasi-continuous logs are obtained from empirical correlations with thermal conductivity, density, and porosity and consideration of mineralogical composition and microstructure. These data give constraints on interpretation and geophysical modeling of, e.g., seismic and gravity data. In the Tertiary postimpact limestone section, the rock fabric (porosity) influences the physical properties. The upper boundary of the impactites is distinctly determined by the high inhomogeneity factor and anisotropy coefficient of thermal conductivity and by the temperature gradient from high-resolution borehole temperature measurements. All physical properties indicate that the upper part of the suevitic breccia can be distinguished from the lower suevite unit. In the Cretaceous megablocks, a high variability of all properties (particularly, thermal conductivity, density of solid material, and temperature gradient) due to the high variability in the mineral composition (calcite, dolomite, anhydrite) is observed.

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“…Thermal fracturing is a standard method for inducing microfractures in samples (Wulff and Burkhardt 1996). Unlike subjecting the rock sample to an external deviative stress field, this approach produces local stress concentrations due to the anisotropic thermal expansion coefficient of the α-quartz grains and this leads to a roughly isotropic distribution of microfractures (Kranz 1983).…”

Section: Heating Of Samplesmentioning

confidence: 99%

The stress dependent elastic properties of thermally induced microfractures in aeolian Rotliegend sandstone

MacBeth

Schuett²

2007

Geophysical Prospecting

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A B S T R A C TThe impact of thermally induced microfractures on the stress-sensitive elastic wave properties of aeolian Rotliegend sandstone samples is analysed. It is found that to identify the effects of the microfracture contribution accurately, a correction must first be made to account for water loss (representing a mass loss of 4-6%) from the pore throats and clays due to the heating process, despite care being taken to ensure that the thermally fractured samples re-adsorb room moisture. Both the original and thermally fractured rocks are stress-sensitive at the ultrasonic wave frequencies of the laboratory. However, a distinct shift in the estimated distribution of internal rock compliance indicates that the population of thermal microfractures differs in nature from that caused solely by core-plug extraction damage. In particular, the ratio of normal to tangential compliance is observed to be higher for the thermally generated microfractures than for the broken grain-grain contacts created by extraction unloading. This can be explained by the intragranular thermal-fracture surfaces being smoother when compared to the intergranular boundaries. Mechanical hysteresis is observed between the up-and downgoing test cycles for both the original and, to a greater extent, the thermally fractured rock. This indicates that there is compactioninduced movement of the fractures in the samples during application of stress in the laboratory.

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The influence of local fluid flow and the microstructure on elastic and anelastic rock properties

Cited by 13 publications

References 20 publications

Numerical simulation of seismic waves using a discrete particle scheme

Numerical simulation of seismic waves using a discrete particle scheme

Integrated interpretation of physical properties of rocks of the borehole Yaxcopoil‐1 (Chicxulub impact structure)

The stress dependent elastic properties of thermally induced microfractures in aeolian Rotliegend sandstone

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