Glass Bead Samples Research Articles

Pore space hydrate formation in a glass bead sample from methane dissolved in water

An experimental device designed and developed to grow methane hydrate in the pore space of a sediment was successfully used with a glass bead sample. The underlying idea for the experiment is that methane dissolved in water is transported with upward moving fluids from its place of origin at greater depths to formations within the hydrate stability field where the methane is removed from the pore water to form hydrate. This process is simulated in a closed loop flow system where methane charged water from a gas/water reservoir outside the hydrate stability field is pumped into the sediment sample cell in the stability field for methane hydrate. The fluid depleted of methane, then flows back into the gas/water reservoir to be recharged with methane. When the experiment was terminated due to blockage of flow by hydrate formation, hydrate saturation was about 95%.

Hyperfiltration of Nacl Solutions Using a Simulated Clay/Sand Mixture at Low Compaction Pressures

It is widely recognized that clays and shales can demonstrate membrane properties. When a hydraulic head differential exists across a membrane-functioning clay-rich barrier, some of the solute is rejected by the membrane. This process is known as hyperfiltration. Some shallow geologic environments, including aquitards bounding shallow perched aquifers and unconfined aquifers, some river and stream beds, and some lake bottoms contain clay–soil mixes. Many engineering structures such as landfill liners, mixed soil augered barriers, and retention pond liners also consist of soil–clay mixes. No previous testing has been performed to investigate the likelihood that hyperfiltration may occur in such mixed soils. Therefore, we performed five experiments using different mixes of Na-bentonite and glass beads (100, 50, 25, 12 and 0% clay) to determine if any of these mixes exhibited membrane properties and to investigate what effect clay content had upon the membrane properties of the soil. Each mixture was compacted to 345 kPa and the sample mixtures were 0.58–0.97 mm thick. All the experiments used an approximately 35 ppm Cl− solution under an average 103 kPa hydraulic head. Experimental results show that all the simulated clay–sand mixtures do exhibit measurable membrane properties under these conditions. Values of the calculated reflection coefficient ranged from a low of 0.03 for 12% bentonite to 0.19 for 100% bentonite. Solute rejection ranged from 5.2% for 12% clay to a high of over 30% for the 100% clay. The 100% glass bead sample exhibited no membrane properties.

Minimizing Instrumental Broadening of the Drop Size Distribution with the M-Fast-FSSP

Abstract A modified version of the Fast-FSSP (the so-called M-Fast-FSSP) is introduced. It allows minimization of the instrumental broadening of measured cloud drop size distributions caused by laser beam inhomogeneities. This is achieved by applying a new technique based on a postexperiment stepwise reduction of the probe's sampling volume. For monodisperse glass bead samples it is shown that the width of the measured size distribution is considerably reduced when applying this technique, especially for large glass bead diameters. The instrumental broadening may exceed a factor of about 4 for a mean glass bead diameter of 30 μm. The M-Fast-FSSP was applied in two cloud measurement campaigns. For two specific cloud cases, the profile of the width of the measured drop size distribution changes significantly when applying the method.

Experimental study of stick‐slip behaviour

AbstractSimple axi‐symmetric uni‐axial compression tests have been realized on dry loose samples of glass beads (diameters d: d=0.2 ± 0.05 mm, 0.75 ± 0.1 mm, or 3 mm) and on Hostun sand under small lateral confinement, σ3<60 kPa, using different sample sizes. The experiments with the two smallest spheres (d=0.2 and 0.75 mm) exhibit stick‐slips, which are characterized by (i) a rapid release Δq of the deviatoric stress q and by (ii) the strain Δε1 separating two events. The samples which exhibit stick‐slip also present a weakening of strength q(ε1) as the rate of deformation dε1/dt is increased. No stick‐slip is generated during the first part of the q−ε1 curve, i.e. when q grows fast with ε1. Four different parameters helped us determine the statistics of Δq and Δε: the lateral pressure σ3′, the rate of deformation dε1/dt, the sample height H, and the diameter D. The statistics do not depend on rate history. They look like exponentials in small samples and/or in (large sample+fast dε1/dt), and they look like Poissonian or Gaussian in (Large sample+small dε1/dt). This change in statistics is attributed to a varying of triggering process starting from a single random event in small samples to multiple random events. We have interpreted this change of statistics as due to some finite size effect so that the representative elementary volume shall contain at least (200)3 grains. Localization of deformation is visible at the end of compression but cannot be detected from stick‐slip statistics nor from q vs ε curve. Copyright © 2004 John Wiley & Sons, Ltd.

Depressurization of fine powders in a shock tube and dynamics of fragmented magma in volcanic conduits

Samples of fine glass beads (mean grain size equal to 38 and 95 μm) have been depressurized within a vertical shock tube. These short-lived, rapid decompressions resemble discrete, cannon-like vulcanian explosions and produce two-phase flows that are inhomogeneous in density in both vertical and horizontal directions because of the presence of bubble-like heterogeneities. We suggest that also volcanic flows may present similar inhomogeneities in density. In the experimental apparatus the flow velocities increase from approximately 1 to 13 m/s when the pressure drop increases from approximately 200 to 900 mbar. A physical model of the initial velocities of expansions in the shock tube has been applied to a range of volcanic overpressures between 0.1 and 20 MPa, suggesting initial velocities of volcanic flows caused by the removal of a rock plug in volcanic conduits between 25 and 400 m/s. During the experiments at large pressure drops, as the mixture expands and moves up the tube, the flow front becomes highly irregular and bubble-like heterogeneities form. The shape of these bubbles becomes distorted and stretched in the turbulent flow. During the experiments at relatively small pressure drops, the sample oscillates when the particles, after the expansion, flow back and bounce upward again. Jets with diameter smaller than that of the tube are ejected from the oscillating samples generating independent pulses. Large bubble-like heterogeneities whose diameter is a significant fraction of the tube diameter can also discretize the flows. Similar mechanisms in real volcanoes may produce pulse-like ejections of gas–particle mixtures out of the vent.

Quantitative analysis of pottery glaze by laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) has been applied for the analysis of old pottery glaze. The plasma is generated by focusing a pulsed Nd:YAG laser on the target at air atmospheric pressure. Quantitative analysis was performed on a number of glass bead samples, and a linear calibration curve with a slope of near unity was obtained. The major glaze elements such as Fe, Ca, Mg, Al and Si were analyzed, and the results were compared with X-ray fluorescence method. Elemental analysis showed that the glaze color difference were due to Fe content variation.

Determination of rock properties by low‐frequency AC electrokinetics

In brine‐saturated rock the existence of a mobile space charge at the fluid/solid interface leads to the electrokinetic phenomena of electroosmotic pressure and streaming potential. The coupling coefficients of these electrokinetic effects, when combined with the conductivity of the brine‐saturated rock, determine the brine permeability of rock exactly. A sensitive low‐frequency AC technique has been used to measure electrokinetic response of a collection of eight rock and four glass bead samples saturated with NaCl brine as a function of salt concentration (fluid conductivity of 0.5 to 6.38 S/m); the response of four of the original 12 samples has also been measured as a function of temperature from 0° to 50°C. All data verify the predicted permeability relationship. Additionally, the frequency response of the electroosmotic pressure signal alone can also be used to determine the permeability, given knowledge of experimental parameters. The concentration and temperature dependence of electroosmosis and streaming potential is found to mostly conform to the predictions of a simple model based on the Helmholtz‐Smoluchowski equation, the Stern model of the electrochemical double layer, and an elementary theory of ionic conduction.

Air Permeability of Porous Materials Under Controlled Laboratory Conditions

AbstractA series of air permeability tests were conducted on four hand‐packed samples of alluvial sands and glass beads using a newly developed air permeameter. The permeameter was tested and found capable of precisely controlling soil‐water matric potential (in the range 0 to 1 bar) while simultaneously facilitating the direct measurement of air permeability in porous media. Permeameter results indicate that air permeability increases with a corresponding decrease in water content over a monotonic drainage cycle. It was observed that the rate of change in air permeability with respect to changes in water content is highest at high water content and lowest at low water content. In several soil samples, the air permeability approached a constant value at low water content. Air permeability variations with water content were observed to differ among soils of different texture. For example, the intrinsic permeability of water was 11 to 86% of the maximum air permeability. The new permeameter allowed rapid and accurate measurements of air permeability in fine‐textured materials over a wide range of matric potentials and water content.

Plastic compaction of cemented granular materials

Abstract We analytically relate hydrostatic stress to strain in a random dense pack of identical spheres cemented at their contacts. The spheres are elastic and the cement is perfectly plastic. This solution for the sphere pack is based on a solution for the normal interaction of two cemented spheres. Initially, the two spheres touch each other at a point. We show that, as loading increases and cement becomes plastic, a finite (Hertzian) direct-contact area between the spheres necessarily has to develop and progress. The stress-strain behavior of the pack depends on the cement's yield limit and on the amount of cement. At the same hydrostatic stress, the deformation of the cemented aggregate is smaller than that of the uncemented one. This difference becomes large as the yield limit increases. We calculate the bulk modulus of an aggregate from the stress-strain curve. In the plasticity domain, the bulk modulus of the cemented aggregate is smaller than that of the uncemented one. The difference between the two may easily reach 50%. Of course, as the cement's yield limit decreases, the aggregate's stress-strain curve and the bulk modulus approach those of the uncemented sphere pack. This theoretical conclusion is qualitatively supported by experiments on epoxy-cemented glass beads. The maximum contact stress in the cemented aggregate may be less than a half of that in the uncemented one. This result explains an experiment where an uncemented glass bead sample failed at a hydrostatic stress of 50 MPa, whereas an epoxy-cemented sample stayed intact.

Design and Test of a Sonic Permeameter for Dry Unconsolidated Porous Materials

We developed a sonic permeameter that can quickly measure the intrinsic permeability of dry unconsolidated porous materials in the laboratory. It consists of a control box, a loudspeaker, and an external waveguide filled with the sample. Sound wave attenuation and dispersion are measured by two microphones recessed in the inner wall of the waveguide. They receive a sound pulse that is sent down to the waveguide from the loudspeaker. The permeability of the sample is then calculated from the attenuation and dispersion spectra using our mathematical model. Test results obtained over several dry Ottawa sand and glass bead samples agree very well with the results obtained using a conventional constant‐head permeameter. The advantage of this apparatus is its rapid and automated measurement, easy operation, and potential workability in the field. Theoretical analysis is also extended to a hypothetical case where the porous material is totally saturated with water.

Temperature and Chemistry Effects in Porous-Media Electrokinetics

ABSTRACTElectrokinetic phenomena in brine-saturated porous media, such as electroosmosis (fluid-flow induced by applied electric fields) and streaming current (the complementary process) depend on the density of ions adsorbed on the pore surface and the characteristic thickness of the diffuse space-charge layer λ. These, in turn, depend on brine chemistry, ambient temperature and possibly other parameters. We report on a series of measurements of natural rock and synthetic glass-bead samples: for one sample group, we varied the temperature over 0–50 ° C; for another, we changed the brine cation species. We find that the electrokinetic coefficients depend only weakly on temperature; this is shown to follow from the expected trends in λ, η, and σ. The chemistry dependence follows qualitatively but not quantitatively the predictions of the Debye-Hiickel approximation.

Scale effects on dynamic wave propagation in heterogeneous media

To study scale‐effects on wave propagation in 3‐D heterogeneous media, we conducted dynamic and static laboratory experiments on seven samples of glass beads cast with epoxy. We measured P and S wave velocities and frequency dispersion by the pulse‐transmission method, and static elastic Young's modulus by a uniaxial stress test. We changed the scale of the heterogeneity by varying the diameter of the glass beads in each sample, and obtained wavelength to scale ratios varying from 0.2 to 20. We observed about 22% P‐wave velocity dispsersion and 15% S‐wave velocity dispersion within this range of wavelength to scale ratios. We observed no scale effects on the static Young's modulus of the same seven samples. It is clear that strong wave velocity dispersion in the experiment is due to the dynamic wavelength‐scale effects caused by scattering.

Influence of microstructure on rock elastic properties

Depending on details of the composite microstructure, different theories may be needed to obtain good agreement with measured elastic properties. This observation is especially pertinent whenever the composite is porous, as is normally true for rocks. Predictions of three theories are compared to data for porous glass samples. The differential effective medium (DEM) theory and Hashin's composite spheres assemblage (H) do a good job of predicting elastic behavior of a porous foam composed of glass. The self‐consistent (SC) effective medium theory does equally well at predicting behavior of a sintered glass‐bead sample. The realizable microstructure of each theoretical model is a good analog of the microstructure for one or the other of these two very different porous glasses. Velocities of granular rocks such as sandstones may be estimated accurately using the SC theory, whereas velocities of rocks such as basalts having isolated cracks and pores may be better estimated using either the DEM theory or Hashin's model.

Shear wave attenuation in dry and saturated sandstone at seismic to ultrasonic frequencies

Ultrasonic and forced-oscillation methods have been applied to measure shear attenuation in Berea sandstone and a fused glass bead sample in the frequency ranges of .03 to 100 Hz and 600 to 1000 kHz. The Qs of dry Berea sandstone at atmospheric pressure falls in the range 100 to 150 for frequencies between .03 Hz and 20 Hz. The ultrasonic results show a much lower Q S (<100) and a strong effect of complete fluid saturation. In the dry Berea samples, Q S is most strongly influenced by frequency at the highest confining pressure of 70 MPa. In all cases, ultrasonic shear Q decreases with increasing frequency. Fluid-flow mechanisms are indicated as the responsible loss mechanisms, both in the saturated samples and in the humid (room-dry) samples.

Effective tortuosity and different acoustic waves in porous media

A simple method has been suggested to estimate the acoustic characteristics of porous structure from a hybrid model—a hybridisation of Biot's phenomenological model and the microscopic multiple-scattering theory which introduces the idea of an effective tortuosity. Without using any adjustable parameter this model may be used to provide rough estimates of the tortuosity, the fast, the shear and the slow sound speeds. The predictions are compared with observation on water-saturated glass bead samples.

沈降天秤による石灰石微粉砕産物の粒度分布測定

The authors developed a chain system sedimentation balance, an electromagnetic sedimentation balance and an improved sedimentation balance for the analysis of particle size distribution of powders. The authors performed particle size distribution analysis on pulverized limestone using an improved sedimentation balance. The present paper describes the reproducibility of measurements by the improved sedimentation balance and selection of a disirable dispersant for the analysis of the pulverized limestone.There was very good reproducibility of measurement in results of particle size analysis performed on samples of spherical glass beads, quartz powder and pulverized limestone. For better reproducibility of measurement, a reduction of scatter of measured values in the large particle size region is advisable.Three kinds of dispersant, sodium hexametaphosphate, Cyquest 3223 and water glass (sodium silicate) were tried for the analysis. As a result, water glass was found to be the most effective dispersant for particle size distribution analysis of pulverized limestone, and the most suitable concentration of the reagent was 2 g/1.

Use of digital image analysis to estimate fluid permeability of porous materials: Application of two-point correlation functions

Scanning electron microscope images of cross sections of several porous specimens have been digitized and analyzed using image processing techniques. The porosity and specific surface area may be estimated directly from measured two-point spatial correlation functions. The measured values of porosity and image specific surface were combined with known values of electrical formation factors to estimate fluid permeability using one version of the Kozeny-Carman empirical relation. For glass bead samples with measured permeability values in the range of a few darcies, our estimates agree well (±10–20%) with the measurements. For samples of Ironton-Galesville sandstone with a permeability in the range of hundreds of millidarcies, our best results agree with the laboratory measurements again within about 20%. For Berea sandstone with still lower permeability (tens of millidarcies), our predictions from the images agree within 10–30%. Best results for the sandstones were obtained by using the porosities obtained at magnifications of about 100× (since less resolution and better statistics are required) and the image specific surface obtained at magnifications of about 500× (since greater resolution is required).

Frequency dependent ultrasonic properties of high‐porosity sandstones

Compressional wave phase velocity and attenuation have been measured in several high‐porosity (20–26%) sandstones as a continuous function of frequency from 400 to ∼2000 kHz. Samples include Massilon, Berea, and Boise sandstones and a synthetic fused glass bead sample. Both dry and brine saturated samples have been studied at effective pressures up to 40 MPa. Dry samples all show negative velocity dispersion (velocity decreasing with increasing frequency) and attenuation (dB/m) increasing as the third to fourth power of frequency. These data are interpreted as evidence of scattering within the samples. Brine saturated rocks show positive velocity dispersion and attenuation increasing with a first‐ to second‐power frequency dependence. These data are interpreted as evidence for a local fluid‐flow loss mechanism. Fused glass beads show no indication of flow related losses.

Multiple scattering effects in water saturated beads

Ultrasonic measurements have been used to study the propagation of longitudinal waves in systems comprised of unconsolidated glass and Plexiglas spherical beads saturated with water. In each sample there is roughly a 20% spread in the sphere diameters. The mean diameters vary between 100 and 500 μm. In every sample the porosity is about 38%. We find that the measured velocity dispersion and attenuation are in generally good agreement with the results of multiple scattering calculations based on the quasicrystalline approximation. In these calculations, the average sphere diameter and porosity of the samples are modeled in terms of the radial (i.e., two site) distribution function, and the scattering properties of the individual spheres are treated exactly. Surprisingly, we find that the properties of the glass and Plexiglas bead samples are remarkably similar. This is true in spite of the fact that the elastic properties of the two materials are quite different. At the lowest frequencies, we show that essentially equal sound speeds for the glass and Plexiglas systems can be understood on the basis of the Biot theory.

Equivalence between 4th sound in liquid He II and the Biot slow wave in consolidated porous media

The theory of acoustic propagation in porous fluid-filled media due to M. A. Biot is applied to the case where superfluid 4He is in the pores (T &amp;lt; 1.1°K). For a consolidated (fused) matrix Biot's slow compressional wave is shown to be identical to the phenomenon known as 4th sound; Rudnick's index of refraction is derived from the Biot theory. Predictions for the velocities of the fast wave, the shear wave, and the slow wave/4th sound are made for fused glass bead samples in which Plona has previously reported seeing these three waves under the condition of water saturation. These predictions for the fused glass beads are made for temperatures less than ∼ 1.1°K, where there is a negligible amount of normal He fluid.