Distribution Of Clay Particles Research Articles

A pore-scale study on the dynamics of spontaneous imbibition for heterogeneous sandstone gas reservoirs

The underlying mechanism for spontaneous imbibition in a water–gas system plays a significant role in hydraulic fracturing in sandstone gas reservoirs. The objective of this study is to characterize the heterogeneity of low-permeability sandstones and investigate their effect on spontaneous imbibition from the perspective of the pore scale. We selected different cores with various pore structures and heterogeneity to evaluate their impact on the dynamics of spontaneous imbibition. The heterogeneities of the cores are contributed from the clay mineral distribution and are characterized through CT scans. The results show that clay minerals have higher CT numbers than the core matrix and that micropores are predominantly distributed in clay particles rather than in the core matrix. Additionally, the water imbibition rate of micropores is larger than that of the macropores, and when the porosities are similar, the water imbibition rate is increased with decreasing permeability. Moreover, the results of 1D frequency scans show that the distribution of water at different locations in the core is governed by the distribution of clay particles. These findings can help us further understand the distribution of fracturing fluids in the heterogeneous low-permeability sandstone reservoirs.

Effects of in situ wetting–drying cycles on the mechanical behaviour of an intact loess

In situ wetting–drying cycles significantly and repeatedly influence the soil water content in the active zone but not in the steady zone. To investigate effects of in situ wetting–drying cycles on the mechanical behaviour of intact loess, a series of pressure plate tests was carried out with an intact loess sampled from the active and steady zones. Results show that the specimens from the steady zone have higher yield stresses at given suctions and a larger inclination of normalized loading collapse (LC) curve than the specimens from the active zone. As evidenced by the scanning electron microscopy results, the clay particles accumulating around the contacts between silt particles are widely observed in the former specimens but not in the latter specimens. The distribution of clay particles in the former specimens results in a stabilized skeleton with mechanical properties sensitive to suction variations. On the other hand, the maximum collapse potential of the specimen from the steady zone is 37% larger than that of the specimen from the active zone, mainly because of the larger inclination of normalized LC curve owned by the former specimen.

Various properties of recycled PET (rPET)/organoclay nanocomposite fibres

ABSTRACTToday, the production of polymeric nanocomposite materials is one of the most important research fields. In this study, it was aimed to investigate the effect of organoclay particles on recycled polyester (rPET) fibre properties. In the literature, the studies mostly concerned with the engineering plastic applications, and hence the investigations were done on pellet and injection-moulded rPET/organoclay nanocomposite samples. Actually, fibre application is the most important market for PET wastes, but unfortunately, there are only a few papers regarding rPET/organoclay composite fibre properties. In the study, rPET/organoclay nanocomposites were prepared by melt intercalation process with different modified organoclay types (3 wt-%), and multifilament fibres were spun by the melt spinning method. Morphological and thermal properties of nanocomposites and surface structure, tensile, and thermal stability properties of the fibres were tested. The results indicated that the distribution of clay particles and organoclay types had a significant influence on various fibres properties.

Core–shell structure acrylamide copolymer grafted on nano-silica surface as an anti-calcium and anti-temperature fluid loss agent

The copolymer (PAAN-SiO2) of acrylamide (AM), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), N-vinylpyrrolidone (NVP) and modified nano-silica (M-SiO2) was synthesized by free radical polymerization in a water solution. The composition, micro-morphology and thermal stability properties of PAAN-SiO2 were characterized by Fourier transform infrared spectroscopy, thermal gravity analysis and transmission electron microscopy (TEM). The results showed that AM, AMPS and NVP were successfully grafted onto the surface of M-SiO2 and formed a spherical core–shell structure copolymer. A significant reduction in the filtration volume was achieved after PAAN-SiO2 added, and this phenomenon was even more pronounced after aging at the high temperature. The filtration volume of base slurry containing 2 wt% of calcium chloride after aging at 180 °C was reduced from 186 to 6 ml after adding 2 wt% of PAAN-SiO2, which exhibited a special property of anti-calcium contamination at high temperature. The interaction mechanism between PAAN-SiO2 and bentonite and calcium ions was analyzed by particle size analysis, scanning electron microscopy, TEM and X-ray diffraction. Because of the stretching of polymer chain under 180 °C that more amide, sulfonic acid groups and cyclic rigid groups were exposed and the strengthening of the connection between PAAN-SiO2 and clay prevents a large amount of ion exchange between Ca2+ and clay layers, reducing the agglomeration of clay. Meantime, the distribution of clay particles was more extensive and some particles with a size of 1–10 μm plugged the micro-nano-pores on the filter cake, and eventually the thin and compact filter cake was formed.

Preparation and Evaluation of Electrical Properties of Plastic Composites Developed from Recycled Polystyrene and Local Clay

In this study, the development of polymer composites was achieved from local clay material and waste polystyrene by cold pressing method, the preparation, electrical, and physical behaviours of clay-polystyrene composites are described. Polystyrene based resin (PBR) was produced from waste polystyrene by solvolysis in petroleum solvent and mixed with the 100μm clay particles at 10%, 20%, 30%, and 40% clay contents. Composite panels were prepared and tested for Physical and electrical properties. Metallurgical microscope was used for the microstructural studies. It was found that with the increase in clay content in PBR from 0 to 40%, there was a rise in density of the composite by about 11% with a simultaneous decrease in the void fraction or porosity from 5.3 % to 1.5%. It was also observed that the polymer composite with the filler loading of 40 wt% has the highest conductivity value of 1.88E-07 S/cm. The comparison of micrographs at 40x and 100x indicated a good dispersion and distribution of clay particles in the polystyrene matrix. The polymer composites produced can be adapted for applications where electrostatic dissipative materials are required.KEYWORDS: Electrical property, iron fillings, plastic composite, recycled polystyrene, clay particles.

The Effect of Palm Trees Root System on the Carbonate Metals and Clay Particle Distribution in Some Soils of the Alluvial Plain.

Eight Pedones distributed in four regions of central Iraq are chosen. Pedone (1) represents Port soil and seven Pedones represent palm groves soils, to study the genesis and composition of the soils with large old palm groves in areas of central Iraq .The Pedones are revealed and described morphologically and obtained the excited soil samples from each horizon for the purpose of conducting physical and chemical analyses. This study shows a discrepancy in the morphological characteristics of the comparison Pedone with palm groves Pedones. It is noted that the existence of diversity in the distribution of volumes of soil minutes . The results show that in some palm groves Pedones that the distribution of total and active clay particle showed certain pattern which represents an increase with the depth as compared with the soil of comparison Pedone that does not show any pattern of distribution, and that due to the role of the root system Corynebacterium of palm trees. That helped in the transmission of the total and active clay particle .The results also refer to the movement of total metals and active carbonate. The results of the chemical characteristics also showed that the degree of soil reaction to that of the comparison Pedone is high as compared with palm groves Pedones and generally ranged from the valuesof the pH between (6.70-8.10) and decline is observed in the proportion of electrical conductivity prospects of palm trees Pedones ranging between (0.45-40.5), while the values of calcium carbonate are ranged (159-350) and the active carbonate are (36-85).

PETROGRAPHY FOR ASSESSMENT OF MOULDING COMPOUND OF ANCIENT POTTERY

Ancient ceramics are the valuable artifacts which saves the information about ancient people and their traditions. The process of making pottery is begun with the choosing and preparation of raw clay and temper material and further applying of different techniques (moulding of vessel, decoration etc.) and finally firing. Petrographical analysis of ancient pottery allows to determine the mineralogical composition of ceramic matrix, the features of their technology and to identify the raw mineral sources (Feliu et al. 2004, Papadopoulou et al. 2006, Bastie et al. 2006). Such kind investigations expand the frames of our knowledge about ancient technological traditions in pottery making. The following characteristics could be determined in thin-sections of ceramic shards: nature and features of plastic and aplastic inclusions; textural and optical characteristics of clay matrix; shape, amount and orientation of pores; features of surface treatment, decoration. This information is animportant for understanding of principles of ancient technologies. The different temper materials inside clay matrix such as sand, crushed rocks, organic materials, shells, grog can be identified accurately using petrography. The ceramic structure and characteristics of mineral changes during the firing are indicators of firing temperatures and atmosphere. A distribution of clay particles and porous inside of ceramic matrix is useful for reconstruction of moulding methods. The study of ceramic collection of the same cultural tradition and from the same region using petrography gives the possibility for differentiation of the natural and cultural factors influenced on the choose of raw materials, variations in the ceramic composition and techniques. This method is one the most precise for identification of an import pottery.

A new possibility for microstructural investigation of clay-based polymer nanocomposite by focused ion beam tomography

This article describes the focused ion beam (FIB)-tomography as a high-resolution three-dimensional (3D) technique to study the morphology of polymer/clay nanocomposites. To establish the structure–property relationship of such composite material, it is very important to visualize the 3D-structure and distribution of clay particles in the polymer matrix. The sequential two-dimensional sectioning by FIB, followed by imaging of dispersed silicate layers using high-resolution scanning electron microscope, and computer reconstruction can show the degree of dispersion of silicate layers in 3D-space.

Combustion behavior of polyethylene/modified montmorillonite clay nanocomposites prepared by ultrasonication

Composites of low density polyethylene with Cloisite 20A clay (OMC) were prepared using ultrasonication. Atomic force microscope (AFM) images showed that ultrasonication could mostly decrease particle size and distribution of clay particles in the polymer matrix. Due to better dispersion of clay and smaller particle size, the flammability properties of PE-LD composites were reduced. Thermogravimetric studies showed that incorporation of OMC to PE-LD matrix improved the thermal stability of samples and enlarge the char yield.

Influence of clay addition on the properties of olive oil in water emulsions

The behaviour of olive oil-in-water emulsions (O/W) was studied in the presence of smectite particles. The distribution of these particles in the emulsions and the effect of their interaction with the surfactant on the stability of the emulsions were investigated. Whereas the variation of surfactant and/or clay content did not seem to affect the nature of the emulsion, it had a significant influence on emulsion stability. This observation led to two main assumptions on the distribution of clay particles within the emulsion, either exclusively in the continuous phase, or also at the oil-water interface. In the absence of clay, the variation of surfactant concentration (from 0 to 17% (w/w)) allowed to distinguish 3 domains. In the first concentration domain (0–4.2%) emulsions stability increased with the content of surfactant. Within the second domain (4.2–8.5% (w/w)), a slight decrease in stability was observed due to flocculation by depletion. For surfactant concentrations equal or higher than 8.5% (3rd domain), emulsion stability increased sharply, probably due to the development of interactions between surfactant molecules as they came closer to their gelling concentration. The effect of clay addition to the aqueous phase (up to 10% (w/w)) on the physicochemical properties of the studied emulsions was assessed from stability, drop size, interfacial tension, rheological and acido-basic analyses. A model based on the location of clay particles either in the bulk or at the interface could be proposed, in which clay particles would interact with surfactant molecules in the bulk phase, and form a mechanical barrier around the oil droplets, thus increasing emulsion stability .

Ultrasonic Preparation of Polymer/Layered Silicate Nanocomposites during Extrusion

Three kinds of polymer/layered nanocomposites were prepared via ultrasonic extrusion. Experimental results showed that ultrasonic oscillations could mostly decrease the size and its distribution of clay particles in polymer matrix. Therefore, crystal size of polymer matrix decreases. For PA6-based nanocomposites with higher compatibility, the ultrasonic oscillations can also affect the microstructure of clay, causing more regions of exfoliated clay. Due to better dispersion of clay and smaller crystal size, the elongation at break of polymer/layered nanocomposites ultrasonically treated got greatly increased, meanwhile ultrasonic oscillations also improved their other mechanical properties, such as tensile and impact strength.

Distribution of clay particles in the spherulitic texture of poly(L-lactide)/organo-modified montmorillonite hybrids

Abstract The distribution of clay particles in the spherulitic texture of poly(Llactide)/ clay hybrids crystallized isothermally at 140°C has been investigated by use of energy-dispersive X-ray microanalysis. After crystallization of the hybrids, the clay particles were found to distribute with almost constant concentration along the radial direction of the spherulites, i.e., they are still kept in stacked state inside the spherulites without any segregation during crystallization. The concentration distribution of the clay particles showed that these particles were incorporated into the spherulitic texture of the crystallized hybrids.

Soil Mineralogy Evolution in the INRA 42 Plots Experiment (Versailles, France)

AbstractNatural soils change by long-term pedogenetic mechanisms, but tillage effects can also strongly affect the evolution of soils, mainly their physicochemical properties. The present paper describes the impact of fertilizers and amendments on soil mineralogy in experimental plots, without plant interaction.The soils of the 42 plots experiment at the INRA experimental station in Versailles (France) have been managed with fertilizers without plant growth since 1929. Strong changes in pH were observed and cation exchange capacities doubled between low and high pH (from 3.6 to 8.2). Strong acidification caused more evolution in the clay particle distribution without selective action on the clay composition.While the clay content varied only slightly, the organic matter content changed considerably, decreasing with non-organic treatment and increasing in the plot with manure treatment. The major clay minerals in the experimental plots are two disordered illite-smectite mixed-layer minerals, with minor amounts of illite/mica and kaolinite. Most treatments effected only minor changes in clay mineralogy. However the illite (non-expandable mineral) content increased in plots with K addition either as KCl treatment or in manure amendments by increasing the illite content and the illite (non-expandable layer) content of the I-S minerals. Manure changed the I-S mineral to a greater extent.

A Mechanism for Development of Stylolites

A sequence of processes is offered by which a rock that is initially almost homogeneous could become stylolitic. The host rock is assumed to contain initially a not-quite-uniform distribution of clay particles that have two properties: when dispersed, they are sites where dissolution of host rock is enhanced, but when concentrated and compacted they can form a low-permeability obstacle to migrating fluids. Initially, compression is isotropic; then extra compression is imposed along some single direction. The first property of the clay causes initial small fluctuations in clay abundance to be self-accentuating, and also leads to development of contrasted layers normal to the extra compression. Flow of solvent parallel to these layers ultimately bifurcates because of the clay's second property. Thereafter, to an increasing extent, flow of solvent takes advantage of those portions of the clay-rich seam that form the sides of stylolitic columns and are not compressed by the extra compression.

A study of late Pleistocene loess deposits, South Canterbury, New Zealand: Part I. Forms and amounts of phosphorus compared with other techniques for identifying paleosols

Four paleosols, and soil horizons within paleosols, were clearly identified in the thick calcium carbonate-free loess sections at Timaru, South Island, New Zealand, by changes in the distribution of total phosphorus and calcium phosphate in the upper 2 m to each paleosol. Extractable manganese was also sensitive in identifying paleosols, particularly the upper horizons. The distribution of bulk density values was useful in identifying paleosols; however, the maximum bulk density (>1.7 g/cc) occurred in horizons identified as B2 rather than fragipan horizons in three of four cases. The distribution of clay particles was useful in understanding the genesis of the modern soil and paleosols, but not in identifying paleosols.

Mojave Playa Crusts: Physical Properties and Mineral Content

ABSTRACT Field observation suggests five distinct crustal types among the playas of the Mojave Desert, southern California, as follows: (1) Hard, dry, smooth, compact and impermeable crusts, generally with low water tables, ordinarily contain in excess of 50 percent clay-size particles, average about 7.0 percent carbonate, and contain about 5.0 percent or less soluble salines. (2) Soft, porous and moderately permeable surfaces ordinarily contain less that 35 percent clay-size particles, average about 2.0 percent carbonate, and contain more than 5.0 percent soluble salines. When clay is covered, introduction of moisture to the surface produces a self-rising ground or surface. High water tables are common to these surfaces and vehicular traffic is poorly supported. (3) Salt pavements, (4) calcareous crusts, and (5) permanently wet crusts constitute three additional types recognized in the field. Combinations of two or more types may also occur in one playa. Salt pavements and wet crusts are often found in the same playa basin with puffy crustal types. These playas, although not distinct crustal types, have been referred to as compound surfaces. Contacts between surface types are gradational and appear to follow definite trends suggesting mineralogic control. Some crusts contain 35-49 percent clay-size particles and moderate amounts of carbonate and soluble salts. Although these surfaces are megascopically indiscernible from clay crusts, they are more susceptible to physical change when exposed to precipitation. These surfaces are considered as a variation of the clay crustal type. Laboratory examination indicates that type depends in a large measure upon the nature, proportions, and particle-sizes of the mineral constituents combined with the presence or absence of moisture. Strength, compaction, and permeability are shown to be interrelated with mineral content. The mineral content of crusts depends in a large measure on lacustrine conditions of sedimentation, largely Pleistocene. The high-carbonate clay crusts as now found appear to demonstrate slow flocculation of clay particles in relatively low alkali-chloride basins. Carbonate or possibly bicarbonate phases may have acted as peptizers which inhibited clay flocculation and led ultimately to a wide, homogeneous, distribution of clay particles. Slow settling of clays resulted in a dense, compact clay mass with a high degree of particle alignment. Mutual clay-carbonate precipitation may have resulted in a surface interaction between the phases. Basin water of high alkali-chlorinity electrostatically induced rapid coagulation of fine particles. The resulting sediment texture was heterogenous, with clay particles aligned in a haphazard manner. Salt, clay, and silts were intermixed. These factors facilitate brine percolation and result in a mineral complex producing puffy, saliniferous, wet, and compound crusts. Local geologic factors may influence ground water and brine movement in crusts so that secondary mineralization may alter original assemblages. These altered areas are generally of minor aerial extent as compared to the playa as a whole, and are easily recognized.

Effect of the shape and distribution of clay particles on shrinkage of products

Effect of the shape and distribution of clay particles on shrinkage of products