Structure Of Fluid Research Articles

Turbulent flow of non-Newtonian fluid in rough channels

Direct numerical simulations of the turbulence of a Herschel–Bulkley (HB) fluid in a rough channel are performed at a shear Reynolds number $Re_{\tau } \approx 300$ and a Bingham number ${Bn} \approx 0.9$ . For the type of rough surface used in this study, the results indicate that Townsend's wall similarity hypothesis also holds for HB fluids. However, there are notable differences compared with the effect of roughness on Newtonian fluids. More specifically, the effect of roughness appears to be slightly stronger for HB fluids, in the sense that the bulk Reynolds number, based on the viscosity at the wall, is reduced further due to the increase in viscosity in the troughs of the roughness surface induced by the low shear. At the same time, for the simulated rough surface, the contribution of form drag to the total pressure drop is reduced from 1/4 to about 1/5 due to the persistence of viscous shear in the boundary layer, reducing its shielding effect. As for the friction factor, due to the nonlinearity of the HB constitutive relation, its use with the wall shear rate from the mean wall shear stress underpredicts the minimum viscosity at the wall by up to 18 %. This inevitably leads to uncertainties in the prediction of the friction factor. Finally, it is observed that the rough surface is unable to break the peculiar near-wall flow structure of HB fluids, which consists of long persistent low-speed streaks occupying the entire domain. This means that the small-scale energy is significantly reduced for HB fluids, even in rough channels, with the energy more concentrated in the lower wavenumber range, implying an increase in the slope of the power spectrum to $-7/2$ in the inertial range, as shown by Mitishita et al. (J. Non-Newtonian Fluid Mech., vol. 293, 2021, 104570).

Optimizing Niclosamide for Cancer Therapy: Improving Bioavailability via Structural Modification and Nanotechnology

Inhibition of multiple cancer-related pathways has made niclosamide a promising candidate for the treatment of various cancers. However, its clinical application has been significantly limited by poor bioavailability. This review will discuss current findings on improving niclosamide bioavailability through modification of its chemical structure and utilization of novel nanotechnologies, like electrospraying and supercritical fluids, to improve drug delivery. For example, niclosamide derivatives, such as o-alkylamino-tethered niclosamide derivates, niclosamide ethanolamine salt, and niclosamide piperazine salt, have demonstrated increased water solubility without compromising anticancer activity in vitro. Additionally, this review briefly discusses recent findings on the first pass metabolism of niclosamide in vivo, the role of cytochrome P450-mediated hydroxylation, UDP-glucuronosyltransferase mediated glucuronidation, and how enzymatic inhibition could enhance niclosamide bioavailability. Ultimately, there is a need for researchers to synthesize, evaluate, and improve upon niclosamide derivatives while experimenting with the employment of nanotechnologies, such as targeted delivery and nanoparticle modification, as a way to improve drug administration. Researchers should strive to improve drug-target accuracy, its therapeutic index, and increase the drug’s efficacy as an anti-neoplastic agent.

Thermodynamic properties and structure of interfacial boundaries in nonionic fluids from the multilayer quasichemical model

The interfacial properties and structure of nonuniform fluids containing complex chainlike molecules and associating species are very much needed in a variety of different fields, including enhanced oil recovery, drug delivery, pharmacy, cosmetics, food processing, etc.Recently, we described the Multilayer Quasichemical Model (MQuM) of a nonuniform fluid that provides a remarkably detailed structural information, including the local concentration and orientation of functional groups of the molecules, the orientation profiles of the chemical bonds in molecular chains and the orientation profiles of the hydrogen bonds in the mixture.In this work, we focus on the description of thermodynamic properties with the aid of MQuM, including the interfacial tension and the profiles of normal and transverse pressures. Before proceeding to more complex systems, a test is performed through comparison with the previously known results from the Scheutjens-Fleer theory for the planar liquid–vapor interface and spherical droplet in one-component fluid of nonpolar monomeric molecules. The model is applied then for planar interfaces between the liquid phases in mixtures of water with n-alkanes of different chain length and for spherical drops in model systems that contain an associating solvent, a nonpolar chain and a nonionic amphiphile. Our theoretical results are compared with experiment, predictions from iSAFT and MD simulation data from the literature. For the spherical droplets, we discuss the model description of the dependence of the interfacial tension on the curvature and estimate the Tolman length. For the planar interface between the equilibrium liquid phases in water – n-alkane mixtures, the interfacial tensions predicted from the model are in good agreement with experiment.

Numerical Simulation of Gas–Water Two-Phase Flow Patterns in Fracture: Implication for Enhancing Natural Gas Production

The main objective of this paper is to investigate the evolution of rock fracture slug structures and decongestion strategies for natural gas extraction processes. For this purpose, the level set method was used to simulate the evolution of the slug structure under the effect of different flow ratios, fracture surface wettability, and fracture tortuosity. The results show that an increase in the water-to-gas flow ratio and fracture tortuosity leads to a significant increase in the proportion of slug structures in the fracture, while an increase in the surface contact angle leads to a decrease in the proportion of slug structures in the fracture. Based on the above slug structure evolution law, a quantitative characterization method for the slug structure of two-phase fluids considering the combined effects of the water–gas flow ratio, average wall contact angle, and flow channel tortuosity was developed. Subsequently, we engage in further discussion on the optimization of the extraction and decongestion process in natural gas extraction.

Building the fracture network model for the Okuaizu geothermal field based on microseismic data analysis

Understanding flow behavior in a geothermal reservoir is important for managing sustainable geothermal energy extraction. Fluid flow in geothermal reservoirs generally occurs in complex existing fracture systems in which the reservoirs are situated in highly fractured rocks. To simulate a discrete fracture model, the location and orientation of the fracture were computed using statistical processes and observational data. In many cases, estimating the location and orientation of fractures from 1D borehole logging data is challenging. In this study, we used microseismic data to build the fracture network systems and extract the detailed positions and dimensions of the fractures. We used the microseismic data recorded at the Okuaizu Geothermal Field, Fukushima Prefecture, Japan, from 2019 to 2021. First, we located the hypocenters, removing the effect of uncertainty in the velocity structure of the geothermal fluids. We relocated and clustered the seismic events based on waveform similarity. We analyzed each cluster to define the fracture orientation using principal component analysis (PCA) and focal mechanism (FM) analysis. We used the P polarity with the S/P ratio as a constraint for a better fault-plane solution. With PCA, we can extract the fracture dimension of each cluster. Our cluster analysis showed that the clusters were not always planar fractures, and we interpreted them as fracture zones. Based on the consistency between PCA and FM, each cluster/fracture zone was classified into three conceptual models to characterize the fracture network system in this field. This model showed variations in the orientation of small fractures within the fracture zone. We characterized the spatial variation in fracture distribution and orientations in the reservoir and demonstrated the fracture network system of this field. The fracture zone near the injection well has a N–S strike, and the dip is above 80°; however, the fracture zone in the northeastern part of the injection well has a NW–SE strike with a dip between 60° and 80°. The fracture network system estimated in this study is crucial for robust reservoir modeling because our model is more realistic, observation-orientated, and includes local anomalies of reservoir properties.Graphical

К вопросу оценки качества сырья из каспийской атерины (Atherina boyeri caspia (Risso, 1810))

The purpose of this work was to establish the informative value of methods of structural analysis of biological fluids in determining the prospects of using atherina (Atherina boyeri caspia (Risso, 1810)) as a source of dietary protein in aquaculture. For the first time, solid-phase structures of atherina muscle homogenates were studied. It is known that the solid phase of biological fluids formed under conditions of wedge-shaped dehydration is a visualization of biochemical processes occurring in an organism or organ. The study of the morphological picture of a dried drop (facies) makes it possible to establish associative links between the features of the structuring of the studied liquid and its composition, as well as to determine the nature of the impact of environmental factors on a living system. The results of the study made it possible to establish the main type of homogenate facies and its morphological parameters, which indicate the consistency of biochemical processes and the presence of high-grade protein in the muscle tissue of the Caspian atherina, caught both in the spring and autumn seasons. The size and weight parameters of fish, the content of water-soluble protein in muscle tissue are characterized. For the first time, a comparative analysis of the level of water-soluble protein and solid-phase structures of muscle homogenates of Caspian atherina caught in different seasons in the coastal waters of Dagestan was carried out. Atherina is a food component for many fish living in the Caspian Sea. It was determined that in October, the content of muscle water-soluble protein in atherina tended to increase relative to March. During the feeding period, the accumulated part of the protein components turns into lipid components, which accumulate intensively, therefore, there are no significant seasonal differences in the content of water-soluble protein. It has been established that the biochemical processes occurring in muscle tissues are reflected in the solid-phase structures of biological fluids formed under conditions of wedge-shaped dehydration. The obtained results of the trend towards an increase in water-soluble muscle proteins in the body and an increase in the population in recent years indicate the importance of the use of Caspian atherina in the quality of live feed at fish farms.

Visualization Of Nanoparticle Orientation Structures Inside Complex Fluids Using Polarized Light Imaging Technique

The present paper reports on the effect of 3D-oriented particles on birefringence using the concept of 'rheooptics', a technique for identifying changes in the internal structure or flow dynamics of complex fluids from changes in optical anisotropy (birefringence). We used the photoelastic method, as a kind of polarized light imaging technique, to visualize the internal orientation structure induced by applying shear stress to cellulose nanocrystal (CNC) suspensions under shear flow. Two different rheometers (concentric cylinder and parallel plate-type) that can easily combine a birefringence measurement system were introduced to Transverse rotation Longitudinal rotation perform the shear flow induction, and the birefringence was measured and compared from vertical and horizontal directions for shear. The birefringence measurements from different directions provide an opportunity to investigate the effect of 3D-oriented CNCs on birefringence, which is a novelty of the present study. The measured birefringence was fitted with the empirical equation proposed in the previous study and followed the power law of applied shear rate with the same exponent, independent of the shear direction at the time of measurement This result suggests that there is a common physical background that gives birefringence a power law. This exponent was different from the values given in previous studies and is explained by differences in the particle interaction behaviour based on the concentration of suspensions and CNC length. Note that the proportionality coefficients differ by a factor of 10, clearly indicating differences due to the direction of birefringence measurement. These results indicate that birefringence due to transverse rotation of the CNC is more sensitive to shear stress than to longitudinal rotation.

Nonequilibrium hyperuniform states in active turbulence

We demonstrate that the complex spatiotemporal structure in active fluids can feature characteristics of hyperuniformity. Using a hydrodynamic model, we show that the transition from hyperuniformity to nonhyperuniformity and antihyperuniformity depends on the strength of active forcing and can be related to features of active turbulence without and with scaling characteristics of inertial turbulence. Combined with identified signatures of Levy walks and nonuniversal diffusion in these systems, this allows for a biological interpretation and the speculation of nonequilibrium hyperuniform states in active fluids as optimal states with respect to robustness and strategies of evasion and foraging.

Unified Understanding of the Structure, Thermodynamics, and Diffusion of Single-Chain Nanoparticle Fluids.

Single-chain nanoparticles (SCNPs) are a fascinating class of soft nano-objects with promising properties and relevance to protein condensates, polymer nanocomposites, nanomedicine, bioimaging, catalysis, and drug delivery. We combine molecular dynamics simulations and equilibrium and time-dependent statistical mechanical theory to construct a unified understanding of how the internal conformational structure of SCNPs, of both a simple fractal globule-like form and more complex objects with multiple internal intermediate length scales, determines nm-scale intermolecular packing correlations, thermodynamic properties, and center-of-mass diffusion over a wide range of concentrations up to dense melts. The intermolecular pair correlations generically exhibit a distinctive deep correlation hole form due to SCNP internal connectivity structure and repulsive interparticle interactions associated with a globular-like conformation on the macromolecular scale, with concentration-dependent deviations at small separations. Unanticipated exponential-like dependences of the equation-of-state, osmotic compressibility, and center-of-mass diffusion constant on SCNP macromolecular packing fraction are theoretically predicted and confirmed via simulations. System-specific behaviors are found associated with SCNP internal structure, but overarching regularities are identified and understood based on a generalized effective globule conformation on macromolecular scales. Diffusivity slows down by 2-3 decades with increasing concentration and is understood as a consequence of a nonactivated excluded volume-driven weak-caging process associated with space-time correlated intermolecular forces experienced by the SCNP. Good agreement between the theory and simulations is established, testable predictions are made, and a quantitative comparison with viscosity measurements on a specific SCNP fluid is carried out. The basic theoretical approach can potentially be extended to treat the chemical and physical consequences of varying the structure of other classes of soft nanoparticles with distinctive internal nanoscale organization relevant in nanotechnology and nanomedicine, and the possible emergence of macromolecular kinetically arrested glasses.

Revealing molecular insights into surface charge and local viscosity in electroosmotic flows

The limitations of the continuum theory in predicting osmotic response at the nanoscale stem from its lack of molecular-level insight into local fluid properties and the interfacial structure of fluid and electrolyte solutions. To overcome this challenge, our study integrates molecular dynamics (MD) simulation with the continuum framework to explore how surface charge and various hydrodynamic properties impact electroosmotic flow (EOF). The failure of continuum theories to account for molecular interactions and geometric boundaries leads to significant disparities between MD simulations and continuum predictions, influenced by local fluid properties and the electric field. Emphasizing the importance of incorporating appropriate local hydrodynamic properties and atomic interface boundary conditions, our findings bridge the gap between MD simulations and continuum EOF predictions. Our computational results and theoretical model, considering surface charge, atomic interface boundaries, and dynamic structure-based hydrodynamic properties, provide crucial insights and guidance for EOF investigations.

Quantitative characterization of 3D pore structures and percolation characteristics in bioturbated reservoir media based on X-ray micro-CT: a case study of the Neogene Sanya Formation in the Qiongdongnan Basin, Northern South China Sea

Organisms alter the primary texture of sediments, leading to alteration in petrophysical properties mediated by a textural and mineralogical contrast between burrow-fill and sediment host, which affects reservoir properties and fluid flow characteristics. In this article, in order to understand the microscopic pore structure and flow state of fluids in microscopic pores of bioturbated reservoirs, Ophiomorpha-bearing bioturbated reservoirs in the Neogene Sanya Formation of the Qiongdongnan Basin in the northern South China Sea were selected to research. Micro-CT was applied to scan selected core plugs, and a 3D pore structure model was established. The geometric characteristics of the microscopic pore structure were quantitatively and visually characterized by a modified maximal ball algorithm, and connectivity analysis of the pore structure was carried out. Numerical simulations of the percolation characteristics of the analyzed bioturbated reservoir samples were performed using digital core software (Avizo) and multi-physics field simulation software (Comsol). The results show that: (1) 3D pore structures reveal that pore volume, pore area, pore equivalent radius, throat area, throat equivalent radius and throat length have a large distribution range; among them, the pore volume has the largest distribution range, which can vary by six orders of magnitude, indicating that the pore size distribution of the bioturbated reservoir is uneven and has strong heterogeneous characteristics; (2) the connected pore structure is very complex, and as the equivalent radius of connected pore increases, the coordination number also gradually increases, the better the connectivity. Numerical percolation simulation results also suggested that larger connected pore space plays a key role in the effective permeability of the reservoir. This study has important implications for analyzing the modification effect of bioturbation on oil and gas reservoirs, and enhancing production and recovery in the study area.

Two-dimensional rheo-optical measurement system to study dynamics and structure of complex fluids

Abstract We have developed a novel rheo-optical measurement system based on two-dimensional polarization analysis, which can evaluate the rheological properties and structure of a complex fluid simultaneously. To assess the utility of the system, we used it to investigate the relationship between yield behavior and structural evolution in a TEMPO-oxidized cellulose nanofiber (T-CNF) suspension, which is a yield-stress fluid that has been actively studied in recent years. To analyze the structural evolution of a T-CNF suspension, stress-ramp tests were conducted. A two-step yield behavior was observed, and distributions of retardation and orientation axis varied dramatically with increasing shear stress. In particular, different distributions were observed in the three regions: after the first yield point, before the second yield point, and after the second yield point. In experiments with a low-concentration T-CNF suspension that exhibits no yield behavior, the retardation increased monotonically with increasing shear stress, and its distribution was uniform. It was demonstrated that the yield behavior and related structures can be analyzed from these results. More detailed structural mechanisms require various rheological tests using the developed system. However, the present insights demonstrate the valuable information provided by the developed rheo-optical measurement system, contributing essential knowledge for applications in various fields.

КОЛИЧЕСТВЕННО-КАЧЕСТВЕННАЯ ХАРАКТЕРИСТИКА КРИСТАЛЛИЧЕСКОГО СТРОЕНИЯ РОТОВОЙ ЖИДКОСТИ ЧЕЛОВЕКА С ИСПОЛЬЗОВАНИЕМ ТЕОРИИ ФРАКТАЛОВ. ЧАСТЬ I

The subject of the study is a dried drop of human oral fluid (facies). The goal is to propose a method for quantitative characteristic for the crystalline structure of oral fluid using fractal theory. The task is to create a computer program to calculate the fractal dimension, the area of crystals; length and width of the axes of mixed human saliva crystals. Methodology. To create a computer program for quantitative description of the crystalline structure of the oral fluid facies. The program was created within the framework of cooperation between Omsk State Medical University and Omsk State Technical University. The program, called FracSquare, was developed using the Python programming language version 3.1 and the built-in libraries math, cv2 and plt, which implement algorithms for finding the Minkowski fractal dimension, searching and counting pixels located inside the desired object, as well as an algorithm for finding the hypotenuse. After installing on the computer and launching the program, you need to load a photo of the saliva facies and calculate the fractal dimension and crystal area by pressing the appropriate buttons; the result will appear on the screen in the form of numerical values. Results. The computer program FracSquare allows you to mathematically calculate the fractal dimension, the area of crystals, and also measure the length and width of the branches of human saliva crystals. These digital values provide a quantitative characterization of the crystalline pattern of the saliva facies. Conclusion. The operator receives accurate digital values using a developed computer program, on its basis he can objectively evaluate the microcrystalline pattern of the facies of human saliva in order to identify pathological processes occurring in the body. The indicator of these processes is oral fluid.

Analyzing Tear Fluid Composition by Synchronous Fluorescence for Diagnosing Dry Eye Disease and the Role of Phytotherapy Intervention

Purpose Tear fluid gained attention as a representative biological fluid. Its simple and non-invasive collection methods as well as richness of candidate biomarkers made it a potential diagnostic tool for different diseases such as dry eye. Synchronous fluorescence spectroscopy is a highly sensitive analytical tool that results in narrowing and enhanced peak resolution, and has a potential role in disease diagnosis, biomarker identification, and therapeutic monitoring. We applied synchronous fluorescence spectroscopy to monitor variations of tear fluid composition during the development of dry eye disease and to evaluate the potential effects of phytotherapy. Methods Dry eye model was induced in Chinchilla rabbits by instillation of 1% atropine sulfate ophthalmic solution. Then, the tear fluid was collected at 3, 7, and 14 days and subjected to synchronous fluorescence spectroscopy. Phytotherapy was achieved by topical instillation of 20 µl of water extracts of pomegranate peel or green tea powders. Results The fluorescence results revealed changes in the structure of tear fluid over time and the eye is subjected to toxification due to oxidative stress. In addition, dry eye disease was found to affect the metabolic/energetic state of the eye. On the other hand, phytotherapy led to enhancement of the metabolic/biosynthesis state due to activation of flavin adenine dinucleotide-associated proteins. Conclusion There was change in the electrical conductivity of tear fluid proteins. In the case of dry eyes, they became electrical insulators, while in the case of treatment with extracts, their electrical conductivity properties improved. The effects of phytotherapy can be related to the high content of ellagic acid and anthocyanin of pomegranate extract, while in green tea, they are related to catechins and phenolic compounds.

Study of Van der Waals forces in nanostructured drilling fluids and their estimation

This article investigates changes in the structure of a nano-drilling fluid developed on the basis of low concentrations and perturbance effect, which manifests itself in the context of interactions of nanosystem particles with the surface of the drill pipe, drill bit and formation. This is done to numerically evaluate the van der Waals forces of intermolecular interaction between contacting bodies as a key mechanism for the formation of nanofilm capable of resisting wear on drilling rigs to increase optimization of the drilling process and reduce operating costs. It is assumed that the stability of a nanofilm structured on the fundamental effect of low concentrations and perturbance is determined not only by the chemical properties of the nanosolution, but also by van der Waals forces, which ensure its adhesion to the surface and improve the aggregation between particles. What is important is the effect of these forces on reducing friction and wear in contact with various surfaces, which can lead to increased efficiency and durability of the drilling process.

Gallium Trichloride Fluid: Dimer Dissociation Mechanism, Local Structure, and Atomic Dynamics.

Molten gallium trichloride emerges as a promising solvent for oxidative metal recycling. The use of supercritical fluid enhances the performance and kinetics of metal dissolution due to significantly lower viscosity in the reaction media. Additionally, the dual molecular nature of gallium trichloride, existing as edge-sharing ES-Ga2Cl6 dimers at low temperatures and high pressure, or flat trigonal GaCl3 monomers in the vicinity of the critical point and low pressures, creates the possibility to tailor the chemical geometry to a particular metallic species. Nevertheless, the mechanism of dimer dissociation, local structure, and atomic dynamics in supercritical gallium trichloride fluids are not known. Using first-principles molecular dynamics, validated by comparison with our high-energy X-ray diffraction results, we illustrate the elementary steps in dimer dissociation. These include the formation of intermediate corner-sharing CS-Ga2Cl6 dimers, the partial disproportionation of GaCl3 monomers at high temperatures and low pressures, changes in the local environment of molecular entities, and unusual atomic dynamics in supercritical fluids.

Structure of liquid-vapor interfaces: Perspectives from liquid state theory, large-scale simulations, and potential grazing-incidence x-ray diffraction.

Grazing-incidence x-ray diffraction (GIXRD) is a scattering technique that allows one to characterize the structure of fluid interfaces down to the molecular scale, including the measurement of surface tension and interface roughness. However, the corresponding standard data analysis at nonzero wave numbers has been criticized as to be inconclusive because the scattering intensity is polluted by the unavoidable scattering from the bulk. Here, we overcome this ambiguity by proposing a physically consistent model of the bulk contribution based on a minimal set of assumptions of experimental relevance. To this end, we derive an explicit integral expression for the background scattering, which can be determined numerically from the static structure factors of the coexisting bulk phases as independent input. Concerning the interpretation of GIXRD data inferred from computer simulations, we extend the model to account also for the finite sizes of the bulk phases, which are unavoidable in simulations. The corresponding leading-order correction beyond the dominant contribution to the scattered intensity is revealed by asymptotic analysis, which is characterized by the competition between the linear system size and the x-ray penetration depth in the case of simulations. Specifically, we have calculated the expected GIXRD intensity for scattering at the planar liquid-vapor interface of Lennard-Jones fluids with truncated pair interactions via extensive, high-precision computer simulations. The reported data cover interfacial and bulk properties of fluid states along the whole liquid-vapor coexistence line. A sensitivity analysis shows that our findings are robust with respect to the detailed definition of the mean interface position. We conclude that previous claims of an enhanced surface tension at mesoscopic scales are amenable to unambiguous tests via scattering experiments.

Magnetoviscous properties of Fe-based amorphous magnetic fluids

Fe-Zr-B amorphous magnetic fluid has been prepared by a chemical reduction method. X-ray diffraction, transmission electron microscope and vibrating sample magnetometer have been utilized for the characterization of the structure, morphology, and magnetic property of Fe-based amorphous magnetic fluids. Besides, the magnetoviscous properties were also investigated. The results indicate that the Fe-Zr-B particles possess a non-crystalline structure with a particle size below 30 nm. The saturation magnetization of the amorphous particles is approximately 55 emu/g, exhibiting extremely low remanent magnetization and coercivity. We also investigated a parameter named Δη*=ηup-ηdown/ηdown, which characterizes the hysteresis effect between viscosity vs magnetic field. The results show that the relatively reduced viscosity △η* is negative below 124 mT, and becomes positive when the magnetic field is higher than 124 mT. We reveal the inverse associations between viscosity and magnetic fields, which can be attributed to the combined influence of thixotropy and magnetic fields. These discoveries present a fresh perspective on the magnetoviscous behavior of magnetic fluids.

Local Structure of Nonuniform Fluid Mixtures Containing Associating and Chainlike Molecules from a Multilayer Quasichemical Model.

In this work, we develop a theory for predicting details of the local structure in nonuniform multicomponent fluids that may contain chainlike and associating components. This theory is an extension─to the fluid interfaces and mesoscopic structures of different geometry─of the multilayer quasichemical model originally proposed by Smirnova to describe liquid solution in the vicinity of a planar solid wall. The basis of the theory is the "cut-and-bond" approach, much in spirit of SAFT, where an infinite attraction between the separated monomeric units of a chainlike molecule mimics the chemical bonds of the chain. We describe the equilibrium structure of the mixture, including the spatial distribution of the monomeric units and the local orientation of the chemical bonds in chainlike molecules, and discuss the contribution of chemical bonds to the local chemical potential in a nonuniform fluid. To test the new theory, we apply it to mixtures containing combinations of model components: a strongly associating solvent, an inert substance of varying chain length, and a chainlike amphiphile. To compare predictions from the multilayer model with the results of continuous description of nonuniform fluids, we also address the square-gradient theory and derive an analytical expression for the influence parameter that takes into account pair correlations in the quasichemical approximation. The multilayer quasichemical model developed in this work predicts formation of aggregates in liquid solution and describes the local structure of the interfaces between the coexisting liquid phases in the mixture. Our theoretical predictions agree on a qualitative level with the accumulated knowledge about the structure of different types of systems studied in this work.

Research and application of low oil-water ratio organoclay-free oil-based drilling fluid technology

This paper introduces the formation and application of a low oil-water ratio organoclay-free oil-based drilling fluid. Shale oil and gas are important alternative energy sources. Due to the extremely complex geological conditions, oil-based drilling fluid technology is commonly used to reduce complexity. Although some achievements have been made, there are still problems such as unstable wellbore, difficult rheological control, and high cost. A stable and low-viscosity water-in-oil emulsion system was successfully prepared by using optimized fatty acid imidazolines emulsifier and alkyl alcohol ether wetting agent, which enabled the oil-based drilling fluid to have a larger solid and water phase capacity. On this basis, a special poly-fatty acid amide rheological modifier was used to assist in the regulation of rheological parameters, resulting in a low-viscosity and high-shear structure of the oil-based drilling fluid. This effectively ensured the efficiency of cuttings carrying while reducing the adverse effects of viscosity on Equivalent Circulating Density(ECD). The low oil-water ratio oil-based drilling fluid technology has been applied in a shale gas drilling platform in southern Sichuan, China, which greatly reduces the cost of oil-based drilling fluid while ensuring drilling efficiency.