scholarly journals Frac sand crushing characteristics and morphology changes under high compressive stress and implications for sand pack permeability

2016 ◽  
Vol 53 (9) ◽  
pp. 1412-1423 ◽  
Author(s):  
Wenbo Zheng ◽  
Dwayne Tannant
Keyword(s):  
Particle Shape ◽  
Void Ratio ◽  
Size Range ◽  
Particle Sizes ◽  
Shale Formations ◽  
Closure Stress ◽  
Compressive Stresses ◽  
Spherical Grains ◽  
Particle Shapes ◽  
Quartz Grains

Sand consisting of round quartz grains is widely used as a proppant during hydraulic fracturing to produce natural gas from tight shale formations. This paper presents results from sand characterization and crushing tests on Jordan Formation frac sand. It includes an assessment of grain-size reduction, changes in particle shape, and reduction in void ratio. It also examines the implications for permeability reduction through a sand pack caused by the closure stress on a hydraulic fracture. The sand from two size ranges (0.6 to 0.71 mm and 0.5 to 0.6 mm) was tested dry under applied compressive stresses of up to 40 MPa in a crushing cup. The overall sand pack stress–strain response becomes softer as grains are crushed. The particle shape shifts from nearly spherical grains to diametrically split grains and then to small elongated and angular fragments for the smaller particle sizes. The permeability of the sand pack reduces by more than 40% at a 20 MPa stress, which is mainly caused by a decrease in void ratio due to compaction. The permeability reduces by over 70% at a 40 MPa stress, which is primarily caused by void ratio decrease, reduction in particle size, and a shift away from spherical particle shapes. Compared to the ISO 13503-2 standard where only the sand crushing percentage after crushing tests is measured, this paper demonstrates that more information can be extracted from sand crushing tests and that sand pack permeability can be assessed to optimize frac sand selection. A sand with a larger size range has a higher crushing percentage, but is more permeable compared to a sand with a smaller size range. This further indicates that frac sand selection based only on sand crushing percentage is not sufficient to achieve better sand pack permeability.

scholarly journals Effects of Particle Shapes and Sizes on the Minimum Void Ratios of Sand

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Zhaoyang Xu ◽  
Ning Xu ◽  
Haibo Wang
Keyword(s):  
Particle Size ◽  
Void Ratio ◽  
Relational Model ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Fines Content ◽  
Minimum Value ◽  
Alternative Materials ◽  
Particle Shapes

The minimum void ratio is an important parameter for evaluating soil properties. It is closely related to the compressive properties, permeability, and shear strength of soil, and it is affected by particle size distributions and particle shapes. However, existing research generally focuses on modeling the minimum void ratio with the effect of particle size distributions, ignoring the influences of particle shapes on the minimum void ratio. This paper analyzes the influences of particle size distributions and particle shapes on the minimum void ratio using four types of sand and alternative materials. The experiments showed that the minimum void ratio first decreased and then increased with the increase of the fines content. The minimum void ratio reached a minimum value when the proportion of fines content was approximately 40%. The more irregular the particle shapes, the more complicated the contact between particles, the more the void existed between the particles, and the larger the minimum void ratio. Based on the experimental data, a relational model between the minimum value of the minimum void ratio and the particle sizes ratio was derived with binary mixtures of different particle sizes and shapes. This proposed model required only one parameter T, which was closely related to the sphericity of the particles, to predict the minimum value of the minimum void ratio with various fines contents. The experiment results showed that the predicted value was very close to the actual measured value.

scholarly journals Characterization of cellulose acetate based on empty fruit bunches and dried jackfruit leaves as replacement candidates for microbeads

2018 ◽  
Vol 67 ◽  
pp. 04024
Author(s):  
Dewi Tristantini ◽  
Andersen Yunan
Keyword(s):  
Water Absorption ◽  
Cellulose Acetate ◽  
Size Range ◽  
Acid Anhydride ◽  
Particle Sizes ◽  
Oil Absorption ◽  
Empty Fruit Bunches ◽  
Alternative Sources ◽  
Beauty Products

Scrubs used in other skin care and beauty products usually contain tiny fine grains of synthetic polymer called microbeads that usually pose threats to marine environment. Empty Fruit Bunches (EFB) and Dried Jackfruit Leaves (DJL) as organic and environmentally friendly can be alternative sources for polymer microbeads. Cellulose acetate is prepared by acetylation reaction between cellulose and acetic acid anhydride. Cellulose from EFB and DJL was extracted through a process of delignification with 12% NaOH treatment for EFB and 10% for DJL to obtain maximum yields of 38.964% and 14.449% respectively, followed by bleaching using peroxide 10 %. The formed cellulose acetate with 88.5% and 79.7% yield respectively is then filtered using a sieve mash 60 and 80 to obtain particle sizes ranging that are in the microbeads size range. The density test resulting in 0.73 g/cm3 and 0.52 g/cm3 respectively for EFB and DJL. Then, physical characteristic test was done by water and oil absorption test with variation at 25°C and 40°C. EFB at 25°C and 40°C shows water absorption at 23.39% and 26.09% and oil absorption at 7.59% and 13.95%. DJL at 25°C and 40°C shows water absorption at 22.56% and 27.32% and oil absorption at 13.09% and 15.36%.

scholarly journals Prediction Model of Minimum Void Ratio for Various Sizes/Shapes of Sandy Binary Mixture

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Chaojie Shen ◽  
Zhaoyang Xu ◽  
Jie Yin ◽  
Jinfeng Wu
Keyword(s):  
Particle Size ◽  
Binary Mixture ◽  
Particle Shape ◽  
Void Ratio ◽  
Soil Mechanics ◽  
Influence Factors ◽  
Natural Sand ◽  
Undetermined Coefficient ◽  
Shape Characteristics ◽  
Different Origins

The minimum void ratio is a fundamental physical index for evaluating particle properties in soil mechanics, ceramic processing, and concrete mixes. Previous research found that both particle size distribution and particle shape characteristics would affect minimum void ratio, while the current research generally uses a linear model to estimate the minimum void ratio of a binary mixture, ignoring quantitative effect of particle shape on the minimum void ratio. Based on a study of binary mixtures of natural sand from three different origins and iron particles of two different shapes, this paper analyzes the influence factors of the minimum void ratio, and a quadratic nonlinear model is proposed for estimating the minimum void ratio of binary mixture. The model contains only one undetermined coefficient, a, the value of which is correlated to the particle sphericity, particle size, and particle size ratio. A theoretical calculation formula for the coefficient a is proposed to quantitatively analyze the effects of these three factors on the size of the parameters. In the end, the model is used to estimate the minimum void ratios of sand and substitute particles from different producing areas; the average difference between the estimated values and the fitted values is about 2.03%, suggesting that the estimated values of the model fit well with the measured data.

scholarly journals The effect of particle shape on the deformation and stress reduction of a gravel soil due to wetting

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Reza Mahinroosta ◽  
Vahid Oshtaghi
Keyword(s):  
Particle Size ◽  
Shear Stress ◽  
Particle Size Distribution ◽  
Normal Stress ◽  
Size Distribution ◽  
Stress Reduction ◽  
Particle Shape ◽  
Particle Breakage ◽  
Direct Shear ◽  
Particle Shapes

AbstractThis paper investigates the effect of particle shape on the stress reduction and collapse deformation of gravelly soil using a medium-scale direct shear test apparatus under different relative densities, normal stress, and shear stress levels. A new method based on the Micro-Deval test was introduced to produce sub-angular particles from angular particles. Therefore, two series of soil specimens were obtained with the same rock origin, particle size distribution, and relative density but different particle shapes. In addition to traditional direct shear tests on dry and wet specimens, a specific test procedure was applied to explore the stress reduction and collapse of soil specimens due to wetting. The results of the tests, including shear stress–shear displacement and vertical displacement-shear displacement, were compared. The results showed that the stress reduction and settlement due to wetting increased with vertical and shear stress levels in both types of particle shapes, with higher values in angular particle shapes. The particle breakage of the soil specimens was also studied quantitatively using the change in the particle size distribution before and after the test. It was shown that the wetting of the samples had more impact on the particle breakage in angular gravel than sub-angular gravel, which increased linearly with the normal stress.

Dynamic Light Scattering at CdSe Nanocrystals and CdSe Cluster-Molecules

2000 ◽  
Vol 636 ◽  
Author(s):  
A. Eichhöfer ◽  
C.V. Hänisch ◽  
M. Jacobsohn ◽  
U. Banin
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
High Performance ◽  
Size Range ◽  
Blue Shift ◽  
Cdse Nanocrystals ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
X Ray

AbstractHigh performance dynamic light scattering (DLS) has been used to determine the hydrodynamic diameters of CdSe-nanocrystals as well as CdSe cluster molecules in a size range of 1 to 10 nm. The method enables the determination of the particle sizes including the ligand shells directly in solution. Consistent with the blue shift of the absorption onset by reducing the particle sizes the values for the hydrodynamic radii decrease. For the CdSe nanoparticles the measured sizes were compared with the diameters determined by TEM experiments; the sizes of the cluster molecules were on the other hand estimated from the space filling models of the single crystal X-ray structure determination. Regarding both types of compounds, DLS yield comparable values for the radii, indicating that it provides a potentially important tool in addition to other size determining techniques like TEM, which operates at more drastic conditions, and powder X-ray diffraction being difficult to interpret below 5 nm.

scholarly journals A discrete interaction numerical model for coagulation and fragmentation of marine detritic particulate matter (Coagfrag v.1)

2021 ◽  
Vol 14 (7) ◽  
pp. 4535-4554
Author(s):  
Gwenaëlle Gremion ◽  
Louis-Philippe Nadeau ◽  
Christiane Dufresne ◽  
Irene R. Schloss ◽  
Philippe Archambault ◽  
...  
Keyword(s):  
Particle Size ◽  
General Circulation ◽  
Size Range ◽  
Circulation Model ◽  
Mass Conservation ◽  
Ocean General Circulation Model ◽  
Global Constraints ◽  
Size Spectrum ◽  
Particle Sizes ◽  
Organic Particles

Abstract. A simplified model, representing the dynamics of marine organic particles in a given size range experiencing coagulation and fragmentation reactions, is developed. The framework is based on a discrete size spectrum on which reactions act to exchange properties between different particle sizes. The reactions are prescribed according to triplet interactions. Coagulation combines two particle sizes to yield a third one, while fragmentation breaks a given particle size into two (i.e. the inverse of the coagulation reaction). The complete set of reactions is given by all the permutations of two particle sizes associated with a third one. Since, by design, some reactions yield particle sizes that are outside the resolved size range of the spectrum, a closure is developed to take into account this unresolved range and satisfy global constraints such as mass conservation. In order to minimize the number of tracers required to apply this model to an ocean general circulation model, focus is placed on the robustness of the model to the particle size resolution. Thus, numerical experiments were designed to study the dependence of the results on (i) the number of particle size bins used to discretize a given size range (i.e. the resolution) and (ii) the type of discretization (i.e. linear vs. nonlinear). The results demonstrate that in a linearly size-discretized configuration, the model is independent of the resolution. However, important biases are observed in a nonlinear discretization. A first attempt to mitigate the effect of nonlinearity of the size spectrum is then presented and shows significant improvement in reducing the observed biases.

scholarly journals VIS-NIR/SWIR Spectral Properties of H2O Ice Depending on Particle Size and Surface Temperature

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1328
Author(s):  
Katrin Stephan ◽  
Mauro Ciarniello ◽  
Olivier Poch ◽  
Bernard Schmitt ◽  
David Haack ◽  
...  
Keyword(s):  
Particle Size ◽  
Spectral Signature ◽  
Particle Sizes ◽  
Icy Satellites ◽  
Spectral Parameters ◽  
Spectral Changes ◽  
Large Particles ◽  
Band Depth ◽  
Increasing Temperature ◽  
Particle Shapes

Laboratory measurements were performed to study the spectral signature of H2O ice between 0.4 and 4.2 µm depending on varying temperatures between 70 and 220 K. Spectral parameters of samples with particle sizes up to ~1360 µm, particle size mixtures, and different particle shapes were analyzed. The band depth (BD) of the major H2O-ice absorptions at 1.04, 1.25, 1.5, and 2 µm offers an excellent indicator for varying particle sizes in pure H2O ice. The spectral changes due to temperature rather, but not exclusively, affect the H2O-ice absorptions located at 1.31, 1.57, and 1.65 µm and the Fresnel reflection peaks at 3.1 and 3.2 µm, which strongly weaken with increasing temperature. As the BDs of the H2O-ice absorptions at 1.31, 1.57, and 1.65 µm increase, the band centers (BCs) of the H2O-ice absorptions at 1.25 and 1.5 µm slightly shift to shorter wavelengths. However, the BCs of the strong H2O-ice absorptions can also be affected by saturation in the case of large particles. The collected spectra provide a useful spectral library for future investigations of icy satellites such as Ganymede and Callisto, the major targets of ESA’s JUICE mission.

The Relationship Between Colliery-waste Particle Sizes and Plant Growth

1974 ◽  
Vol 1 (4) ◽  
pp. 281-284 ◽  
Author(s):  
Christopher G. Down
Keyword(s):  
Particle Size ◽  
Plant Growth ◽  
Water Retention ◽  
Size Range ◽  
Growth Period ◽  
Dry Weight ◽  
Particle Sizes ◽  
Small Particles ◽  
The Relationship ◽  
Water Holding

Seed germination and dry-weight production in Lolium perenne were examined in relation to growth on 12-years-old colliery waste separated into seven size-fractions. The size-range was from more than 4,000 μ to less than 125 μ, and the growth period was up to 30 days. Germination percentages after 6 days generally increased with decreasing particle-size, as did dry-weight. Shoot : root ratios also showed an inverse relationship with particle size.After 30 days there was no distinction between dryweights on different particle sizes, except that on the largest fractions it had been found impossible to keep the plants alive. Problems of water-holding capacity are discussed, and the significance of soil particle-size in revegetation work is examined, it being concluded that an admixture of small particles is important for water retention and plant growth.

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