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pore collapse and grain crushing on ultrasonic

Effects of pore collapse and grain crushing on ultrasonic

Aug 21, 2007· [32] When pore collapse and grain crushing take place (at P = P*), the crack density ρ raises from 0 to a mean value of 0.1 (curve 3). An anomalous feature just beyond P * is that crack densities inferred from equations (8) and (9) become different: Inversion of G moduli gives a ρ value close to 0.2, whereas inversion of K moduli data gives a

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Effects of pore collapse and grain crushing on ultrasonic

Effects of pore collapse and grain crushing on ultrasonic velocities and V p/V s Je´roˆme Fortin,1 Yves Gue´guen,1 and Alexandre Schubnel2 Received 20 August 2005; revised 13 February 2007; accepted 6 June 2007; published 21 August 2007. [1] Compressional, shear wave velocities and their ratio, V p/V s, were measured along with

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(PDF) Effects of pore collapse and grain crushing on

50 pore collapse and grain crushing (nonlocalized cataclastic 51 flow) [ Zhang et al.,1990; W ong et al.,1997]. 52 [ 3 ] Recent field [ Mollema and Anto nellini,1996], and

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Effects of pore collapse and grain crushing on ultrasonic

2 Effects of pore collapse and grain crushing on 3 ultrasonic velocities and V p/V s 4 Je´roˆme Fortin,1 Yves Gue´guen,1 and Alexandre Schubnel2 5 Received 20 August 2005; revised 13 February

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Effects of pore collapse and grain crushing on ultrasonic

At a critical effective confining pressure P*, a large mechanical decrease of porosity was observed that was due to pore collapse and grain crushing. Theoretically, two different processes are affecting the elastic wave velocities in counteracting ways during cataclastic compaction: cracking

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CiteSeerX — 2 Effects of pore collapse and grain crushing

At first, increase in hydrostatic pressure was 9 accompanied by a simultaneous increase of both Vp and Vs as expected. At a critical 10 effective confining pressure P*, a large mechanical decrease of porosity was observed that 11 was due to pore collapse and grain crushing.

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2 Effects of pore collapse and grain crushing on 3

2 Effects of pore collapse and grain crushing on 3 ultrasonic velocities and Vp/Vs . By Re Schubnel. Abstract. a large mechanical decrease of porosity was observed that 11 was due to pore collapse and grain crushing. Theoretically, two different processes are 12 affecting the elastic wave velocities in counteracting ways during cataclastic

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Effects of pressure on pore characteristics and

The effective pressures in our experiments were too small to change the shapes of most grains and pores, as grain crushing occurs only at pressures above Effects of pore collapse and grain crushing on ultrasonic velocities and Vp/Vs, J. geophys. Mechanisms affecting ultrasonic wave propagation in fluid-containing sandstone under high

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X-Ray Imaging for Compaction Band Characterisation in

Aug 17, 2015· o grain crushing and pore collapse Challenge o to study compaction bands at the laboratory scale using a combination of advanced non-destructive experimental methods Focus herein o x-ray imaging (density variations) Study material Vosges sandstone o ~22% porosity o 93% quartz, 5% feldspar, 1% kaolinite, 1% mica (+ some oxides)

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4.4 Compression failure: Pore collapse GitHub Pages

4. 4 Compression failure: Pore collapse. If compression stresses are high enough, grains can crush filling the pore space. Pore collapse may happen in nature due to rock burial and also in petroleum engineering during reservoir depletion. In both cases effective stresses increase in all directions.

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On Pore-Scale Imaging and Elasticity of Unconsolidated

Understanding the elastic properties of unconsolidated granular media is crucial for interpreting seismic and sonic log data in soils and unconsolidated petroleum reservoirs. Rock and soil deformations are often estimated indirectly using rock physics models that relate changes in elastic properties to pore compliance. The complex microstructure of geological materials in represented by simple

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Simulation of localized compaction in high-porosity

mechanics of compaction, such as bond/grain breakage and pore collapse. A notable exception is the work by Das et al. [16,21],inwhich the explicit incorporation of grain crushing allowed the authors to point out the importance of the rheological response on the simula-tion of both onset and propagation of compaction bands.

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Estimation of pore microstructure by using the static and

Jan 01, 2019· Experimental measurements of the static and dynamic bulk compressibilities of the two sandstones are shown in Fig. 4.As discussed in Section 2.2, if the relation between stress and strain (or wave velocities) is known, the expressions of the static (dynamic) bulk compressibility can be derived.The fit is shown in Table 1.For Navajo sandstone, the estimated crack porosity is 0.079% by using the

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The compressibility and shear characteristics of soils

Sep 10, 2014· Field and Shuttle Radar Topographic Mission data were used to create Digital Elevation Model and geologic maps to study the roles of geology, discontinuities, elevation, steep slopes, deep valleys, and drainage patterns on the frequent occurrence of long-travel landslides along the Nigeria–Cameroon border. The undrained shear behaviors of sandy specimens from two localities

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Sun CHAO PhD Student Geologie ResearchGate

A saturated Bleurswiller sandstone, of 25% porosity, was compacted by increasing the confining pressure over the critical pressure P* which characterizes the onset of pore collapse and grain crushing.

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Characterizing the nonlinear interaction of S- and P-waves

Jan 16, 2015· The nonlinear elastic response of rocks is known to be caused by the rocks' microstructure, particularly cracks and fluids. This paper presents a method for characterizing the nonlinearity of rocks in a laboratory scale experiment with a unique configuration. This configuration has been designed to open up the possibility of using the nonlinear characterization of rocks as an

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Shear-banding in drained and undrained triaxial tests on a

clues to understand the behaviour of rocks at large stress when pore collapse and grain crushing are important. A challenging issue is the modelling of grain crushing phenomenon and its influence on the hydro-mechanical properties. Grain crushability can be included in the modelling procedure using discrete element analysis [18, 19].

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solid/fluid substitution scheme constrained by pore-scale

To ensure Gassmann consistency, Glubokovskikh et al. modelled the compliant pores as grain-to-grain contacts open into stiff pores. Compliant pores are modelled as thin circular disks with traction-free edges. The Effects of pore collapse and grain crushing on ultrasonic velocities and Vp/Vs, J.

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On the pore-scale mechanisms leading to brittle and

Various different ways to model pore collapse also have been proposed and among them, Wang et al. [29] used grain shrinkage to simulate intra-granular cracking and grain crushing processes. In these models, porosity is derived based on the spaces generated from the random assembly of the circular disks or spherical particles.

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Effect of carbonation on the hydro-mechanical properties

Dec 01, 2009· In a second stage, the deviatoric stress was unloaded and the argon pore pressure was progressively increased and stabilized to 28 Effects of pore collapse and grain crushing on ultrasonic velocities and V-p/V-s. Journal of Geophysical Research — Solid Earth, 112 (2007) B08207-16 p. Google Scholar.

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