Clay Size Research Articles

Differences in soil biological activity and soil organic matter status only in the topsoil of Ferralsols under five land uses (Allada, Benin)

Land use change on the Ferralsols of the Allada Plateau in southern Benin has led to a slight decline in soil organic carbon (SOC) stocks over the last two decades. However, as in many African landscapes, detailed characterisation and quantified data on the SOC stocks and soil biological activity under major land uses are still poorly understood. The aim of this study was to characterise the biological activity and organic matter status of Ferralsols (0–30 cm) under the five major land uses on the Allada Plateau, i.e., forests, tree plantations, young and adult palm groves, and croplands (pineapple, maize). Soil biological activity was assessed using the standardised litter decomposition method (Tea bag index) and soil respiration (during a 28-day soil incubation). Soil organic matter status was characterised by quantifying SOC pools: soil microbial biomass carbon (MB-C), potassium permanganate oxidisable carbon (POX-C), and SOC associated to soil particle-size fractions (e.g. particulate organic matter, POM, and SOC associated to the clay soil fraction). The results indicated that SOC pools and biological activity were lower in tree plantations than in forests. The standardised litter decomposition was also slower in tree plantations than in forest. In croplands and palm groves, SOC pools and soil microbial biomass and respiration were lower than in forests and tree plantations. This high level of biological activity in forests, and at a lesser level in tree plantations, was effective in accumulating carbon in C pools associated to the clay fraction. Agricultural land uses, such as croplands and palm groves decreased all the soil C pools even those associated to the clay fraction, except for POX-C. However, these land-use effects on SOC pools decreased strongly with depth. At 10–30 cm, the differences in SOC pools or soil respiration between the five land uses were no more noticeable. Our results indicated that the amount of organic inputs was an essential factor to sustain high soil biological activity and SOC stabilisation in the clay size fraction, but only in the topsoil. Maintaining forests in the landscape is a priority in order to preserve SOC stocks and soil biological activity, which neither monospecific tree plantations nor cultivation can do at the same level.

Preservation of groove mark striae formed by armoured mud clasts: The role of armour sediment size and bed yield stress

AbstractStriated grooves in tool marks are common at the base of sandstones, especially in deep‐marine successions, but their use in physical‐process and environmental reconstruction is underdeveloped. To fill this gap in knowledge, striations in the central groove of chevron marks and in chevron‐less groove marks were formed in the laboratory by dragging tools armoured with silt, sand or gravel across muddy substrates. These experiments simulated the formation of striated grooves by armoured mud clasts carried at the base of quasi‐laminar and fully laminar debris flows, aiming to: (1) delineate the bed shear strengths for the formation of striated grooves at different armour sediment sizes; (2) examine how the preservation potential of striated grooves depends on clay bed rheology and size of armour sediment and (3) discuss how the pre‐lithification clay bed consolidation state and size of armour sediment can be reconstructed from striated grooves in the geological record. The experimental results revealed that tools with small‐diameter silt and sand armours dragged along soft beds lack striations or, at best, leave poorly defined striations, whereas firm beds and gravel armours exhibit well‐defined striations. The spacing of striations formed by gravel clasts corresponds well with the clast diameter, implying that striation spacing is a good proxy for the diameter of armoured gravel under natural conditions. In contrast, the spacing of striae formed by sand armours is greater than the grain diameter, suggesting that the spacing of fine striations can only be used to predict a maximum armour sand size. A comparison of different processes of formation of armoured mud clasts demonstrated that the armouring of mud clasts most probably happens after incorporation of the clasts by erosion into the head of the debris flow and subsequent movement across a loose sandy or gravelly bed surface.

Provenance of clay-sized detrital sediments in the North Sea and the Skagerrak region based on radiogenic Nd-Sr-Hf isotopes and clay mineral compositions: assessing the impact of coastal and seabed erosion

The Skagerrak basin represents the main sink area for fine-grained sediment in the North Sea region and constitutes a natural deposition center for sediments that are supplied from the Atlantic, the Baltic Sea and the surrounding continental margins and coasts. However, the exact sources and their proportional contributions to the North Sea sediments and to the Skagerrak deposits are not well understood. To trace the predominant sources of the sediment and to gain a better understanding of the sedimentary processes in the North Sea and the Skagerrak basin, radiogenic Sr, Nd, and Hf isotope signatures and clay mineral compositions of the detrital clay fraction of surface sediment samples from the North Sea, the Scandinavian margins and the Baltic Sea were measured. The results indicate that the major source for Skagerrak clay-size sediments is the northern North Sea but Scandinavia as well as the southern North Sea including the southern England coast also contribute material. Seabed and coastal erosion in the northern North Sea are enhanced by the inflowing Atlantic Currents, which provide the Skagerrak with high amounts of clay size sediments. In contrast, the southern North Sea, the Baltic Sea and mid-European rivers such as Weser, Elbe and Ems are only minor contributors. As Skagerrak deposits are dominated by clay sized material (up to 60%), the reconstructed sediment processes in this study deviate from findings in previous sediment budget studies, which were based on both clay and silt fraction and indicated predominant influences from the southern North Sea. These results highlight that coastal and seabed erosion in the North Sea is a previously underestimated source of fine-grained sediments for depocenters in the entire North Sea. With regard to climate change, the global sea-level rise will likely enhance erosional processes and can therefore significantly influence the sediment budget of the entire North Sea.

A Regional Shallow Décollement at the Front of the Mexican Fold and Thrust Belt: Microstructure of the Santiago Shale

Abstract This contribution analyses the role played by the mechanical properties of a decollément shale layer in the evolution of the Mexican Fold and Thrust Belt (MFTB). The mobility of overpressured shales can accommodate large strains by grain-scale plastic mechanisms, and affect the folding and thrusting styles of the overburden. Research on shale deformation mechanisms is necessary to improve the knowledge of these processes and their influence on the structural style of fold and thrust belts. The ductile behavior of rocks involving grain-scale plasticity was documented in the Jurassic Santiago shale sequence using geological mapping, microstructural observations on thin-oriented sections, and scanning electron microscopy (SEM) imaging. Structural styles such as detachment folding, fault-bend folding, and shale-cored fold-thrusts were observed at the regional scale. At the outcrop scale, the shale developed strong foliation and pencil cleavage, with immersed packstone boudins. Observed structures include thrusting, soft and open folds, and buckle folding. In thin section, the ductile textures include a strong penetrative foliation with lenticular and wavy-parallel laminae composed of carbonates, ribbons of reoriented clays and organic matter (clay+OM), s-c structures, porphyroblasts microtextures, development of oblique cleavage concerning folded foliation (crenulation cleavage), and carbonates dissolution. The Santiago shale shows also evidence of brittle deformation including calcite-filled fractures and cataclastic gouges. X-ray diffraction (XRD) analysis of the clay size fraction suggests that the authigenic calcareous shale was deformed in conditions of the deep diagenetic zone (between 100 and 200°C) and fluid overpressure (>70 MPa). The results help to improve the understanding of ductile microstructure and its role in shale deformation cretaceous cover, promoting the formation of localized fault propagation folds in the overburden. This study aims to open new perspectives in the kinematics and rheology interpretations for this sector of the MFTB, highlighting the role of the décollement layers during the progression of the orogen.

Investigation and modeling of physicochemical properties of bentonite-chitosan composites versus the concentration of chitosan added by intercalation

This study attempts to understand the relationship between structural and physicochemical changes of clay modified by a chitosan intercalation, and to valorize the clay-chitosan composites for wastewater treatment purpose. More precisely, the main aim was a characterization and modeling of the physicochemical properties of clay-polymer composites (especially bentonite-chitosan composites) versus the concentration of chitosan added by intercalation. We first developed a method for intercalating chitosan into the clay matrix, with different polymer concentrations (6g/L, 12g/L, 18g/L, 24g/L, 27g/L and 30g/L). Second, we carried out a characterization of the structural and physicochemical properties of clay-polymer composites based on X-Rays Diffraction (XRD), Fourier Transform Infrared (FTIR) and Scanning Electric Microscopy (SEM). In particular, the results of these analyses show that the measured pores within the composites with chitosan concentrations 6g/L and 30g/L are of nanometric order, while the composite at 12g/L is rather of microscopic order. Third, XRD measurements allow the determination of the clay interlayer space (basal distance) and particles size versus the polymer concentration. For basal distance, we have demonstrated the existence of five regimes depending on the value of the polymer concentration, namely (i) dilute regime, (ii) first semi-dilute regime, (iii) well-regime, (iv) second semi-dilute regime and (v) saturation regime. Finally, these bentonite-chitosan composites may be used as kinds of filtration membranes for wastewater, retaining, for example, a dye whose adsorption quantity was found to be improved by an amount of 76.92 %.

Evaluation of Aminated Nano-Silica as a Novel Shale Stabilizer to Improve Wellbore Stability.

The issue of wellbore instability poses a significant challenge in the current exploration of shale gas reservoirs. Exploring more efficient shale stabilizers has always been a common goal pursued by researchers. In this paper, a novel shale stabilizer, denoted as ANS, was prepared by employing a silane-coupling modification method to graft (3-Aminopropyl) triethoxysilane (APTES) onto the surface of nano-silica. The structure of ANS was characterized through Fourier transforms infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), and particle size tests (PST). The shale stabilizing properties of ANS were evaluated through tests such as pressure penetration, BET analysis, hydration expansion and dispersion. Furthermore, the interaction between ANS as a shale stabilizer and clay was explored through clay zeta potential and particle size analysis. The results indicated that ANS exhibited a stronger plugging capability compared to nano-silica, as evidenced by its ability to increase the shale pressure penetration time from 19 to 131 min. Moreover, ANS demonstrated superior hydration inhibition compared to commonly used KCl. Specifically, it reduced the expansion height of bentonite from 8.04 to 3.13 mm and increased the shale recovery rate from 32.84% to 87.22%. Consequently, ANS played a dual role in providing dense plugging and effective hydration inhibition, contributing significantly to the enhancement of wellbore stability in drilling operations. Overall, ANS proved to be a promising shale stabilizer and could be effective for drilling troublesome shales.

Property of Modified Bovine Bone Glue as an Environmental Additive in Water-Based Drilling Fluids.

At present, animal bone glue (BG) is being widely used in many fields, but there are no studies reported on oilfield chemistry. In this paper, an environmental water-based drilling fluids additive named bromoethane-modified bone glue (BG) was developed by using bovine bone glue and bromoethane as raw materials, anhydrous ethanol as solvent, sodium hydroxide as alkaline hydrolysis agent, and sodium carbonate as a system pH regulator. The inhibition, filtration performance, and temperature resistance of BG were evaluated. Performance study results show that the linear swelling rate of sodium bentonite (Na-MMT) was decreased from 50.2% (in tap water) to 38.2% (in 4 wt % BG solutions), and filtration loss was reduced from 30 mL (in tap water) to 12 mL (in 5 wt % BG). Hot-rolling experiments show that the BG solution still exhibits good performance even after 16 h × 130 °C. The reasons for BG to achieve excellent performance were analyzed through scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), ζ potential, thermogravimetric analysis (TGA), and microstructure. The results of SEM and FT-IR show that BG can fully dissolve in water and adsorb on the surface of clay particles by relying on its own adsorption functional groups such as -OH and -COOH. When 4% BG was added, ζ potential analysis revealed that the clay particle size declined by 0.502 μm, which indicated that BG can inhibit clay hydration swelling dispersion.

Toward soil carbon storage: The influence of parent material and vegetation on profile-scale microbial community structure and necromass accumulation

Soil microbial communities play a crucial role in the accumulation and stabilization of soil organic carbon (SOC) through complex processes involving plant residue transformation and mineral interactions. These processes are influenced by plant inputs and modulated by soil properties that are mostly determined by the parent material. However, our understanding is limited regarding the manner in which vegetation and parent material affect microbial community structure, necromass accumulation, and their subsequent impact on SOC storage. To bridge this knowledge gap, we conducted an in-depth investigation focusing on the top-down influence of vegetation type and the bottom-up effect of parent material on microbial-mediated carbon transformation across soil profiles in a tropical region. Our study encompassed 42 sites on three parent materials (basalt, granite, and marine sediments) and four vegetation types (rubber, banana, areca plantations and uncultivated grassland). Soil samples were collected at 0–20, 20–40, 40–80, and 80–100 cm depth. Microbial community structure and necromass were quantified using microbial biomarkers of phospholipid fatty acids and amino sugars, respectively. In rubber plantations, we observed a trend toward higher microbial biomass that, though not significant when compared to other vegetation types, transformed to a significantly higher accumulation of microbial necromass. This increase in microbial necromass was linked to the accumulation of SOC facilitated by the presence of clay size minerals in clayey soils developed from basalt. In particular, basaltic soils were dominated by bacteria, which facilitated the accumulation of bacterial necromass that significantly bolstered its contribution to SOC. In contrast, in sandier soils developed from granite and marine sediments, fungal communities and necromass dominated due to the propensity of fungi for coarser soil environments. Overall, the main impact of vegetation on microbial communities and necromass accumulation was primarily demonstrated for the topsoil. Differences in soil texture arising from different parent materials exert significant effects on the fungal-to bacterial-biomass and necromass ratios, consequently influencing the contribution of fungal and bacterial necromass carbon to SOC across soil profiles. Our study underscores the pivotal role of parent material in governing tropical profile-scale soil carbon storage by shaping the structure of microbial communities and influencing the retention of microbial necromass.

The Lower Silurian Longmaxi rapid-transgressive black shale and organic matter distribution on the Upper Yangtze Platform, China

The characteristics and formation of maximum flooding (MF) black shales are important aspects in defining the geology of fine-grained reservoirs. The MF black shales are located at the bottom of the Longmaxi Formation on the Upper Yangtze Platform, corresponding to graptolite zone LM1. Seismic interpretation, X-ray diffraction entire rock analysis, total organic carbon (TOC) tests, and field emission scanning electron microscopy analysis indicate that the MF black shales have an average content of 49.3% quartz (85% clay size), 10.5% calcite, 8.4% dolomite, and 23.4% clay minerals. The quartz content increases basinward, whereas the clay mineral content decreases. The shale has developed during rapid sea level rise, with a thickness of 0.5–2.8 m that gradually thickens basinward. The TOC content, averaging 5.4%, gradually decreases basinward, with four distinct stacking patterns. The mineral composition and thickness of the Longmaxi shale are related closely to rapid transgression, biology, and volcanism during the period of sedimentation. Rapid transgression has led to a decrease in terrestrial input and shale thickness. In addition, biological activity and volcanism have caused the prevalence of microcrystalline quartz. Shales with high TOC content are related to anoxic conditions, along with low sedimentation rates and high primary productivity. The combination of an anoxic water column, weak dilution, and enhanced organic matter (OM) supply have enhanced the preservation of the OM. The four TOC stacking patterns are related to the water depth. The supply of clay minerals decreases with increasing water depth, whereas the degradation and recycling of OM decrease the TOC content. The sediment accommodation increases with increasing water depth, resulting in four TOC stacking patterns.

Shear response of iron ore tailings under monotonic loadings

Dry stacking is a disposition method that is quickly becoming a trend for the mining industry in Brazil. With several cases in which compacted mine tailings are positioned on the top of hydraulically disposed tailings which were placed into pits. The present research assessed the mechanical response of hydraulically disposed iron ore tailings collected from a pit that was formerly a mining site. To better understand the mechanical behaviour of mine tailings under such conditions, the investigation of their monotonic response is of great importance. The studied material was classified as a silty sand with traces of clay size. A very loose condition with distinct confining stresses was tested monotonically on a simple shear equipment. Simple shear tests were performed in an apparatus that can directly measure pore pressure, guaranteeing an effective stresses analysis. A plane strain condition was applied on fully saturated samples under undrained loading conditions. Results showed the agreement of the strength envelopes of monotonic stress paths, the effective friction angle of the material was 33.2° and no cohesive intercept.

Molecular dynamic simulation study on interaction mechanism between biopolymer and kaolinite

The mining industry produces enormous amounts of waste annually. These wastes – mine tailings – predominantly consist of clay size particles with the major clay mineral being kaolinite. Due to its colloidal nature, kaolinite is generally separated using polymeric flocculants. Recently, biopolymers have been explored in place of synthetic polymers as a flocculant. Researchers have previously investigated kaolinite-biopolymer surface interaction mechanisms by inferring using bench scale physical tests. However, there is a lack of clear understanding of exact interactions between kaolinite and biopolymers at the atomistic scale. In this study, molecular dynamic simulation is used to investigate the interaction mechanism(s) at the atomistic scale between sodium carboxymethyl cellulose (anionic) and a kaolinite surface at neutral pH (7). Molecular dynamic simulation was also performed with a kaolinite surface with deprotonated edges to identify interaction mechanisms. Hydrogen bonding and cation bridging interaction mechanisms were identified from the visualization of interacting atoms. Simulation results have been supplemented with sedimentation test results and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy results.

Assessing the Impact of Erosion and Farming Practices on the Spatial Distribution of Topsoil Characteristics in a Sloping Vineyard Using an Open-source QGIS Software

Erosion is one of the major threats that negatively affect agricultural soils. Several studies indicated that sloping vineyards are prone to soil erosion due to the soil management method. This study was conducted in a sloping vineyard planted in 2019 (with a slope of 100 and a slope length of 38 m) in Thu Cuc commune, Tan Son district, Phu Tho province, Vietnam. The main objective of the study is to evaluate soil characteristics (pH, particle-size distribution, organic matter, cation exchange capacity (CEC), N, P, and K macronutrients) related to terrain morphology, soil erosion, and farming practices. The open-source QGIS software was used to evaluate the spatial distribution of the soil characteristics. We found that the organic matter content, CEC, and clay content in the soils taken at the footslope zones were higher than those at the top of the hill as a result of soil erosion. In contrast, higher contents of K and silt were observed at the top of the hill compared to the footslope, indicating an unapparent impact of soil erosion on these two factors in the studied vineyard. Phosphorus was evenly distributed throughout the plot and influenced by the soil characteristics. Indeed, a strong correlation between total P content and soil pH, organic matter, and silt content was revealed in our study. On the other hand, cultivation practices exerted a significant impact on the prevailing accumulation of soil organic matter, CEC, total N, and clay particle size at the lower part of the vine rows following the horizontal flow. The vine rows were planted along the contour lines rather than the dominant slope of the vineyard can explain this tendency. In addition, no cover crops sown between the vine rows probably resulted in intense soil erosion at the steepest part of the terrain. Overall, the terrain morphology and farming practices played an essential role in the spatial distribution of soil characteristics. Therefore, integrating geographic information systems into building a digital database and predicting the spatial distribution of soil parameters is necessary to perform soil quality monitoring and serve sustainable land management.

Evaluation of soil texture classification from orthodox interpolation and machine learning techniques

The current investigation examines the effectiveness of various approaches in predicting the soil texture class (clay, silt, and sand contents) of the Rawalpindi district, Punjab province, Pakistan. The employed techniques included artificial neural networks (ANNs), kriging, co-kriging, and inverse distance weighting (IDW). A total of 44 soil specimens from depths of 10–15 cm were gathered, and then the hydrometer method was adopted to measure their texture. The map of soil grain sets was formulated in the ArcGIS environment, utilizing distinct interpolation approaches. The MATLAB software was used to evaluate soil texture. The gradient fraction, latitude and longitude, elevation, and soil texture fragments of points were proposed to an ANN. Several statistical values, such as correlation coefficient (R), geometric mean error ratios (GMER), and root mean square error (RMSE), were utilized to evaluate the precision of the intended techniques. In assessing grain size and spatial dissemination of clay, silt, and sand, the effectiveness and precision of ANN were superior compared to kriging, co-kriging, and inverse distance weighting. Still, less than a 50% correlation was observed using the ANN. In this examination, the IDW had inferior precision compared to the other approaches. The results demonstrated that the practices produced acceptable results and can be used for future research. Soil texture is among the most central variables that can manipulate agriculture plans. The prepared maps exhibiting the soil texture groups are imperative for crop yield and pastoral scheduling.

Ferric Oxyhydroxylsulfate Precipitation Improves Water Quality in an Acid Mining Lake: A Hydrogeochemical Investigation

Hydrogeochemistry of a lignite pit lake in Lusatia, Germany, was investigated. Anoxic groundwater from the dump aquifer rich in FeII (average ~5911 µmol/L) and SO4 (average ~14,479 µmol/L) contents enter the lake as subsurface inflow; oxidation and subsequent precipitation of poorly crystallized Fe-oxyhydroxysulfate (schwertmannite) occurs and causes acidification (pH~2.8). However, the removal of dissolved loads as solid phases significantly improves the groundwater quality of the downgradient as an outflow. The rainwater isotopic values (δD ~−8.88‰ and δ18O ~−65.86‰) closely matched with the groundwater showing very little isotopic modification, which points to a short residence time of groundwater. The displacement of δD and δ18O values (slope = 5.3) from the meteoric water line reflected the evaporative enrichment of the lake water. The isotopic signature also revealed longer residence times of epilimnion than the hypolimnion waters which are dominated by groundwater. The lake is dimictic and showed abrupt changes in physicochemical parameters along the interface (~0.30 m thick) when separating the epilimnion (upper 4 m) from the hypolimnion (bottom 1.5 m). Lake sediments were found to be dominated by clay size fraction occurring as laminations (thickness: 1~0.5 mm) that reflect seasonal sedimentation. Higher schwertmannite formation in the south as compared to the north (recharge side) also serves as a scavenger of potentially toxic elements which is probably a natural solution to man-made problems. Schwertmannite transformation to goethite releases sulfate which is reduced and fixed as secondary sulfide minerals over time. Overall, waters are of a Ca–SO4 to Ca–Mg–SO4 type with distinct inflow (FeII/FeIII > 2.5) and outflow (FeII/FeIII < 0.5) of groundwater.

Fijación de fosforo en sedimientos de fondo de los Ríos Paraná, Paraguay y Bermejo

Phosphorus sorption'from Solutions containing 0-5 mgP/l was studied in bottom sediments from Paraná, Paraguay and Bermejo rivers. Sorptidh frtted a Langmuir isotherm with phosphate sorption capacities of 96, 87 and 52 MgP/g (dry weight) sediment. Hieltjesand Lijklema (1980) phosphorus fractionation showed that the iron bound phosphate is the mainfraction in the Paraná and Paraguay sediments while the calcium bound phosphorus is the main fraction in the Bermejo sediments. Caleiuhi content was high (32 mg/g) in the Bermejo sediments and low (5.5 and 5;3 mg/g) in the Paraná and Paraguay sediments, respectively, The organic matter composition is also dlfferent in the three rivers being the Paraná and the l^íraguay ríchér in huihic ^ibstánces. Low phosphorus content and sorption capacity in the three sediments are thought to be related with a granulometry dominated by the coarse fractions. Clay size partióles only accounted for 13-23 % of the total sediment weight.

Hysteresis in Soil, Its Causes and Influences

Soil hysteresis is a natural phenomenon that occurs in soil water retention curve (SWRC) and soil water characteristic curve (SWCC), the mismatch of the drying (drainage or desorption) and wetting (sorption or adsorption) curves in each curve is called hysteresis in soil, i.e., At any potential (Ψ), there is a discrepancy between the soil water content (Θ or ű) in the curve of desorption and adsorption, this indicates that the amounts of water collected during the desorption cycle are not the same as the amount of water for adsorption the soil at the same applied pressure (suction Ψ). So, this relationship between soil water content (Θ or ű) versus soil water potential (Ψ) is non-unique. The difference is caused by a number of mechanisms, including: Contact Angle (θ), Adsorption, Bubble-form, Matric potential, Ink-Bottle Effect, Entrapped Air, Wetting and Drying History and Pore Size... etc. The explanations concern both (water and soil). Soil hysteresis has a degree, that varies depending on the type of clay minerals and pore size... etc. In this review paper, what are the causes of soil hysteresis, the hysteresis degree, and what does it influence? will be discussed.

Study of Geotechnical Properties of Clays in the Laylan Region and their Suitability in the Brick Industry in Northeastern Kirkuk, Northern Iraq

The research dealt with the study and evaluation of geotechnical characteristics, which included tests of the specific gravity, grain-size analysis, and Atterberg Limits, chemical and mineralogical analyses of samples from the Laylan region, northeast of Kirkuk and the possibility of using them as raw materials in the brick industry. The samples have 31.5% clay, 46.25% silt, and 22.25% sand. From this, it turns out that all samples consist mainly of grains the size of clay and silt and small amounts of sand, and thus the deposits of the region are of a nature (Sandy mud ) according to Folk classification. The results of the soil consistency showed that the soil is of a low to medium plasticity type depending on the plasticity scheme within the standard classification of soils and that it can be formed and take suitable plasticity for the brick industry. Chemical analyses revealed that SiO2 and CaO are the clay deposits main components, indicating the high content of quartz and calcium carbonate, The mineralogical analysis by X-ray diffraction techniques indicated that quartz, calcite, feldspar, gypsum, and dolomite are the non clay minerals; Kaolinite, illite, palygorskite and chlorite are the most clay mineral .

Synthesis of an Eco-Friendly Xylooligosaccharides and Its Mechanistic Evaluation in Water-Based Drilling Fluids

This study investigates the preparation and application mechanism of Xylooligosaccharides (XOS), an environmentally friendly oligosaccharide additive derived from black fungus in water-based drilling fluids (WBFs). The distinctive molecular characteristics of XOS are revealed through Fourier-transform infrared spectroscopy. Thermogravimetric analysis confirms its stability at temperatures below 150 °C. In terms of performance enhancement, incorporating XOS improves rheological properties and filtration efficiency. Elevated XOS concentrations increase viscosity, diminish fluid loss, suppress clay hydration, and enhance cohesive strength, especially at higher temperatures. Additionally, incorporating XOS prompts the formation of a lubricating layer on particle surfaces, facilitating improved interaction between particles and the surrounding fluid. This layer substantially reduces friction coefficients, thereby significantly boosting the lubrication efficiency of the drilling fluid. At the microstructural level, the incorporation of XOS leads to noticeable microstructural refinement in the matrix mud cake, resulting in a smoother particle distribution due to interactions between XOS and particles. Mechanistically, introducing XOS results in a significant shift in the distribution of clay particle sizes. This phenomenon can be attributed to XOS’s ability to create a stable hydration film within the WBFs. As a result, this film mitigates particle aggregation, leading to a reduction in particle size. XOS emerges as a versatile and sustainable oligosaccharide inhibitor, effectively optimizing the performance of WBFs. Its diverse contributions to lubrication, inhibition, and microstructure refinement position XOS as a promising solution for efficiently extracting oil and gas resource.

Pore-Scale Analysis of the Permeability Damage and Recovery during Cyclic Freshwater and Brine Injection in Porous Media Containing Non-Swelling Clays

Permeability damage in subsurface porous media caused by clay mobilization is encountered in many engineering applications, such as geothermal energy, water disposal, oil recovery, and underground CO2 storage. During the freshwater injection into rocks containing brine, the sudden decrease in salinity causes native clay fines to detach and clog pore throats, leading to a significant decline in permeability. The clay fines detach due to weakened net-attractive forces binding them to each other and the grain. Past experiments link this permeability damage on the immediate history of the salinity and the direction of flow. To better understand this phenomenon, we conducted pore-scale simulations of cyclic injection of freshwater and brine into sandstone containing Kaolinite clay. Our simulations establish a link between the clay-fine trajectory and the permeability trend observed by Khilar and Fogler (1983). For a uniform clay size of 3 microns, we observe a permeability decline by two orders of magnitude during freshwater injection with respect to brine injection. Increasing salinity and simultaneously reversing flow direction restores the permeability. The permeability restoration upon reversing the brine flow direction is attributed to the unblocking of pore throats in the reverse direction by the movement of the clay particles along the grain surfaces by the hydrodynamic force and the strong net-attractive force under high salinity.

Efficient Demulsification Performance of Emulsified Condensate Oil by Hyperbranched Low-Temperature Demulsifiers.

Focusing on the problem of poor demulsification performance of light crude oil emulsions in low-permeability oilfields at low temperatures, the composition of the emulsion samples, clay particle size distribution, and the viscosity-temperature relationship curve of samples were analyzed. Based on the results of emulsion composition analysis and characteristics, the bottle test method was used to analyze the demulsifying effect of different commercial types of demulsifiers, revealing the demulsification mechanism. The field tests confirm the demulsification capabilities of Polyoxyethylene polyoxypropylene quaternized polyoxyolefins surfactants (PR demulsifiers). The results reveal that PR demulsifiers combine the features of decreasing the interfacial tension between oil and water and adsorbing SiO2, allowing for quick demulsification and flocculation at low temperatures. This research serves as a theoretical and practical foundation for the study and advancement of low-temperature demulsification technology in oilfields.