Emulsion Flow Research Articles

Conformance control in heterogeneous two-dimensional sandpacks by injection of oil-in-water emulsion: Theory and experiments

Oil-in-water (O/W) emulsion flow tests were conducted in visual and heterogeneous two-dimensional (2-D) models in which the crossflow between the high (HPZ) and low permeability zones (LPZ) can be modelled. Impacts of emulsion droplet size on promoting crossflow between the two permeability zones were investigated. Emulsion flood pattern and outflow percentage from the two heterogeneous zones show that injection of O/W emulsions with an appropriate range of droplet sizes can induce crossflows between the two permeability zones, thereby resulting in the water mobility conformance in the heterogeneous 2-D model. Two types of crossflow were observed in the experiments and verified in the numerical modeling: flow redistribution at the injection boundary and crossflows in the emulsion-invaded area. A new mathematical model was established to capture the dynamics of 2-D emulsion flow. A finite element method was used to obtain the solution of the mathematical model, and the experimentally observed emulsion conformance control processes were successfully predicted. Mathematical analyses on emulsion concentration distribution, velocity field and pressure distribution reveal that it is the capillary resistance contributed by the emulsion that changes the pressure distribution in the two permeability zones; therefore, the changed pressure distribution affects the local flow in the two permeability zone and thus influences the outflows. The proposed emulsion flow model is compatible with a standard reservoir simulator, providing a potentially efficient and useful method of simulating field-scale emulsion flow for designing conformance control process.

Hydraulic damping nonlinearity of a compact hydro-pneumatic suspension considering gas-oil emulsion

Hydro-pneumatic suspension (HPS) systems could attenuate broad-frequency-range vibration mainly via the nonlinear hydraulic damping property. While the strut design with shared gas-oil chamber leads to gas-oil emulsion within strut chambers which intricately affects the fluid flows between the coupled chambers and thus the damping force. This study investigated the temperature- and frequency-dependent hydraulic damping properties of a compact hydro-pneumatic suspension strut, in terms of the flow discharge coefficients. A laboratory experiment was performed at nearly-constant strut temperature of 30, 40 and 50 °C, in the frequency range of 0.5-8 Hz. The obtained experimental data are used to identify the discharge coefficients of the emulsion flow across bleed orifices and check valves, which determine the damping property of the considered strut. An analytical model is established, and the simulation results obtained under different strut temperature and excitation frequencies showed reasonably good agreements with the experimental data. The results suggested greater discharge coefficient of the bleed orifice than that of the check valve, which might be due to the relatively complex structure of the check valves. Greater excitation frequency was shown to decrease the discharge coefficients in a nonlinear manner, irrespective of the strut temperature. Greater strut temperature, however, leaded to greater discharge coefficient of the check valve. Increasing the excitation frequency from 0.5 Hz to 8 Hz resulted in nearly 14 % decrease in the discharge coefficient of check valve at a constant strut temperature of 50 °C.

Encapsulation of yacon (Smallanthus sonchifolius) leaf extract by supercritical fluid extraction of emulsions

Extracts with biological activities need to be preserved, as they can be degraded if exposed to light or heat. This work reports results of microparticles formation of yacon leaf extract with modified maize starch as encapsulated agent using Supercritical Fluid Extraction of Emulsions (SFEE). The variable investigated were pressure (9–13 MPa) and emulsion flow rate (QE) (0.5–1.5 mL/min) on the encapsulation efficiency (EE) and residual ethyl acetate content. The highest EE was 68.2 %, performed at 9 MPa and QE of 1.5 mL/min. The obtained particles were spherical, with size ranging from 92 to 450 nm. Analyses showed that: (i) the particles presented an amorphous characteristic; (ii) there was no degradation of the extract during the encapsulation; (iii) the SFEE improved the preservation of the antioxidant activity of the samples. This study shows the potential of using a new technology for particle production.

A Method for Estimating Equivalent Shear Rate in Flow Field of Crude Oil Production

Turbulent shear is a common flow characteristic of crude oil production. The shearing effect simulation is still a big challenge for the study of oil-water emulsion and multiphase flow. In this paper, based on the physical description of the shearing flow field and numerical simulation of the flow field characteristics, we established a method for estimating the equivalent shear rate in the well bore and well head areas, considering the change of the watercut and gas-liquid ratio parameters of the crude oil. The simulation results indicate that the watercut has little effect on the equivalent shear rate, and under the same watercut, the equivalent shear rate increases with the gas-liquid ratio. When the gas-liquid ratio increased from 240:1 to 430:1, the equivalent shear rate at the well bore and well head areas increased 84% and 76% respectively, with the watercut of 80%. The results of this study contribute to a theoretical understanding of oil-water emulsion behavior simulation of the multiphase flow characteristics.

Дослідження течії палива в розпилювачі форсунок при використанні спиртових добавок в емульгованих паливах

The article analyzes energy crops as sources of raw materials for the production of biofuels and mixtures thereof. The agricultural plants from which alcohol is produced as an additive to biodiesel fuel have been studied and classified. Cereal crops (wheat, barley, rye, oats) are the most promising raw materials for making alcohol additives in emulsified fuel. The analysis of bioethanol production technologies is carried out and the main technical advantages and disadvantages are identified. The article identifies that the production of bioethanol and other by-products is becoming increasingly popular with the use of deep grain processing. It has been found that the improvement of diesel performance on emulsified fuels is explained by the fact that the droplets of emulsified fuel formed after its injection into the combustion chamber (KZ) consist of particles of heavier fuel (in the case considered below - rapeseed oil). within which are particles of easily boiling fuel (ethanol). The dimensions of these particles typically range from one to several micrometers and are virtually independent of fuel spraying conditions. As a result, the use of emulsified fuels in diesels can reduce the smoke of VG, reduce emissions of nitrogen oxides, and reduce fuel consumption. It should be noted again that during the fuel in the flowing part of the nozzles of the nozzles, which is characterized by high speeds, high Reynolds numbers, there are some local hydraulic losses and discontinuous flows. Areas where reduced pressure, gas phase, and two-phase fuel flow may occur. In this regard, the calculation of such flows is also a rather complex hydrodynamic problem, which requires the use of specialized software complexes (PCs). In the computational studies, the simulation of a stationary flow of oil DP and emulsion of 70% RO and 30% ES in the flowing part of the atomizer with maximum lifting of the needle of the nozzle 0,32 mm.

Double emulsion flow cytometry with high-throughput single droplet isolation and nucleic acid recovery.

Droplet microfluidics has made large impacts in diverse areas such as enzyme evolution, chemical product screening, polymer engineering, and single-cell analysis. However, while droplet reactions have become increasingly sophisticated, phenotyping droplets by a fluorescent signal and sorting them to isolate individual variants-of-interest at high-throughput remains challenging. Here, we present sdDE-FACS (single droplet Double Emulsion-FACS), a new method that uses a standard flow cytometer to phenotype, select, and isolate individual double emulsion droplets of interest. Using a 130 μm nozzle at high sort frequency (12–14 kHz), we demonstrate detection of droplet fluorescence signals with a dynamic range spanning 5 orders of magnitude and robust post-sort recovery of intact double emulsion (DE) droplets using 2 commercially-available FACS instruments. We report the first demonstration of single double emulsion droplet isolation with post-sort recovery efficiencies >70%, equivalent to the capabilities of single-cell FACS. Finally, we establish complete downstream recovery of nucleic acids from single, sorted double emulsion droplets via qPCR with little to no cross-contamination. sdDE-FACS marries the full power of droplet microfluidics with flow cytometry to enable a variety of new droplet assays, including rare variant isolation and multiparameter single-cell analysis.

The Role of Emulsions in Steam-Assisted-Gravity-Drainage (SAGD) Oil-Production Process: A Review

SummaryStudies that investigate and attempt to model the process of steam-assisted gravity drainage (SAGD) for heavy-oil extraction often adopt the single-phase-flow assumption or relative permeability of the moving phases as a continuous phase in their analyses. Looking at the emulsification process and the likelihood of its prevalence in SAGD, however, indicates that it forms an important part of the entire physics of the process. To explore the validity of this assumption, a review of prior publications that are related to the SAGD process and the modeling approaches used, as well as works that studied the emulsification process at reservoir conditions, is presented. Reservoir conditions are assessed to identify whether the effect of the emulsion is strong enough to encourage using a multiphase instead of a single-phase assumption for the modeling of the process. The effect of operating conditions on the stability of emulsions in the formation is discussed. The review also covers the nature and extent of effects from emulsions on the flow mechanics through pore spaces and other flow passages that result from the well completion and downhole tubing, such as sand/flow-control devices. The primary outcome of this review strengthens the idea that a multiphase-flow scenario needs to be considered when studying all flow-related phenomena in enhanced-oil-recovery processes and, hence, in SAGD. The presence of emulsions significantly affects the bulk properties of the porous media, such as relative permeability, and properties that are related to the flow, such as viscosity, density, and ultimately pressure drop. It is asserted that the flow of emulsions strongly contributed to the transport of fines that might cause plugging of either the pore space or the screen on the sand-control device. The qualitative description of these influences and their extents found from the review of this large area of research is expected to guide activities during the conception stages of research questions and other investigations.

A METHOD FOR OPTIMIZING THE DOSING OF DEMULSIFIER AT A COMPLEX OIL PROCESSING UNIT


 
 
 The process of dosing demulsifier is considered by changing its consumption depending on the consumption of oil emulsin at the installation inlet. The oil emulsion flow ratio and the rate of change of the demulsifier level, which leads to a change in the consumption of the demulsifier, is determined. The proposed process allows to reduce the cost of oil refining by increasing the accuracy of dosing. The whole complex oil processing unit (COPU) is a single block module. The delivery set includes a technological unit, a control unit, furnaces and heat exchangers, automatic furnishing and maintenance units. COPU should be equipped with valves and flow sensors as well as, other means of monitoring, control and regulation, as well as, instruments for testing and emergency protection systems. Operation of COPU control is carried out using an automated system, both remotely and locally. In the process of oil preparation, monitoring and measurement must be carried out the regulation of technological parameters, if necessary. Various comprehensive training facilities correspond to various indicators of economic efficiency, in particular: indicator of energy consumption, complexity of technology; costs of installation, operation, maintenance of installations (including the cost of servicing personnel); the complexity of the oil preparation process.
 
 

Connecting the Drops: Observing Collective Flow Behavior in Emulsions

Thoroughly mixing immiscible fluids creates droplets of one phase dispersed in a continuum of the other phase. In such emulsions, the individual droplets have rather mundane mechanical behavior. However, densely confining these suspended droplets generates a packing of particles with a spectacular diversity of mechanical behavior whose origins we are only beginning to understand. This mini review serves to survey a non-exhaustive range of experimental dense slow flow emulsion work. To embed these works in the context of the flow behavior of other structured fluids, we also discuss briefly the related non-local flow modeling attempts as one of the approaches that has been used successfully in describing emulsion flow properties and other materials.

Water-based nano-PCM emulsion flow and heat transfer in divergent mini-channel heat sink—An experimental investigation

In this work, an experimental investigation is performed to study the water-based nano-PCM emulsion flow and heat transfer in the divergent mini-channel heat sinks (MCHSs). The divergent rectangular MCHS is selected in this study as it provides a higher heat transfer along with smaller value of pressure drop as compared with the parallel one. The water-based microencapsulated n-eicosane PCM suspension is considered as the coolant. Indeed, the particles of microencapsulated n-eicosane PCM are suspended in the water. The diameter of these particles is 130 nm. The divergent angle of 2.06° is used for fabricating the divergent mini-channels. The influences of various parameters such as the Reynolds number, the heat flux, and the concentration of nano-PCM particles on the thermal resistances, the figure of merit (FOM), the friction factor, coefficient of performance (COP), and the heat transfer effectiveness are investigated. The findings of this study indicate that the mean and maximum thermal resistances decrease about 0.5% and 4.92%, respectively by increasing the input heat flux from 40.38 W to 60.08 W at Re = 100 for the case of base fluid. The maximum FOM value is equal to 1.02 that can be achieved at ωPCM = 2%, Re = 305, and qh″=4.79W/cm2. Using the nano-PCM emulsion with a large concentration increases considerably the pressure drop penalty and provides a poor FOM index. The mean heat transfer effectiveness is higher than unity for smaller values of the Reynolds number. However, the mean heat transfer effectiveness diminishes for larger values of the Reynolds number.

An Experimental Study of Emulsion Flow in Alkaline/Solvent Coinjection with Steam for Heavy-Oil/Bitumen Recovery

SummaryWater is the dominant component in steam-injection processes, such as steam-assisted gravity drainage (SAGD). The central hypothesis in this research is that in-situ oil transport can be enhanced by generating oil-in-water emulsion, where the water-continuous phase acts as an effective oil carrier. As part of the research project, this paper presents an experimental study of how oil-in-water emulsion can improve oil transport in porous media at elevated temperatures.Diethylamine (DEA) was selected as the organic alkali that generates oil-in-water emulsions with Athabasca bitumen at a 1,000-ppm NaCl brine and a 0.5-wt% alkali concentration. This aqueous composition had been confirmed to be an optimum in terms of oil content in the water-external emulsion phase at a wide range of temperatures. Then, flow experiments with a glass-bead pack were conducted to measure the effective viscosities of emulsion samples at shear rates from 5 to 29 seconds−1 at 35 bar and temperatures from 373 to 443 K.Results show that the oil-in-water emulsions were more than 15 times less viscous than the original bitumen at temperatures from 373 to 443 K. At the shear rate of 5 seconds−1, for example, the emulsion viscosity was 12 cp at 373 K, at which the bitumen viscosity was 206 cp. The efficiency of in-situ bitumen transport was evaluated by calculating the bitumen molar flow rate under gravity drainage with the new experimental data. Results show that oil-in-water emulsion can enhance the in-situ molar flow of bitumen by a factor of 273 at 403 K and 345 at 373 K, in comparison with the two-phase flow of oil and water in conventional SAGD. At 443 K, only a fraction of bitumen is emulsified in water, but the bitumen transport by both oil-in-water emulsion and an excess oil phase in DEA-SAGD can enhance the molar flow of bitumen by a factor of 19 in comparison to SAGD. This is mainly because the mobility of the bitumen-containing phase is enhanced by the reduced viscosity and increased effective permeability. A marked difference between alkaline solvents and conventional hydrocarbon solvents is that only a small amount of an alkaline solvent enables enhancing the in-situ transport of bitumen.

Structural and Mechanical Properties of Water Oil Emulsions of Highly Viscous Oils

The results of the study of the process of formation of emulsions in high viscosity oils are presented. The effect of the oil composition and the content of the aqueous phase on the microstructure, rheological properties, and activation energy of the viscous flow of oil-water emulsions are shown. Based on the analysis of the group composition of oils and the intermediate layer formed during the separation of emulsions, an increase in the mass fraction of benzene, alcohol-benzene resins, and asphaltenes in the intermediate layer is established.

Effect of Nano-Clay Cloisite 20A on water-in-oil stable emulsion flow at different temperatures

In Enhanced Oil Recovery (EOR) operations, water-in-oil emulsions are often used to ensure good sweep of the crude in the flooding process. Dispersions of 70% water in 30% oil (diesel) were extensively used to move the crude in the porous medium with good results. The present paper is concerned with a study on the influence of Cloisite 20A Nano-Clay particles particularly on the hydrodynamic performance and the stability of water-in-oil emulsions at different temperatures between 25 °C and 45 °C. The experimental results showed that the presence of Cloisite 20A stabilized the water-in-oil emulsions compared to the dispersion without Nano-Clay. It was found that the Nano-Clay concentration affects the emulsion viscosity depending on mainly the water volume fractions. In general, small quantities of the Nano-Clay reduce emulsion viscosity, while higher concentrations of the Nano-Clay resulted in a clear increase of the emulsion viscosity. The results also revealed the percentage of pressure drop reduction at different temperatures as a function of the concentration of Nano-clays, oil/water ratios and emulsion flowrates. The influence of fluid temperature on pressure drop reduction is higher than the influence of Nano-Clay concentration especially at low flowrate.

Experimental study on thermal performance of water-based nano-PCM emulsion flow in multichannel heat sinks with parallel and divergent rectangular mini-channels

In this work, an experimental study is arranged to investigate the cooling efficacies of water-based nano-PCM emulsion flow in the multi-channel heat sinks with parallel and divergent rectangular mini-channels. N-eicosane particles with size of 130 nm are considered as the phase change material (PCM) nanoparticles. Two multi-channel heat sinks with eight parallel and divergent mini-channels are fabricated. The divergent channel has a divergent angle of 2.06°. The effects of different parameters including volumetric flow rate of working fluid (60 cm3/min <Q̇ < 600 cm3/min), heat flux (3.2 W/cm2 <qh′′ < 4.8 W/cm2), Reynolds number (100 < Re < 1000), and mass fraction of PCM nanoparticles (0% <ωPCM < 10%) on the dimensionless wall temperature, the Nusselt number, the cost of performance (COP), and the pressure drop are investigated. The experimental results show that the nano-PCM emulsion can improve heat transfer in both parallel and divergent mini-channel heat sinks as compared with the pure water. At Rebf = 965 and qh′′ = 3.21 W/cm2, the average Nusselt number in the parallel mini-channel heat sink improves about 15.2% by adding the PCM nanoparticles with mass fraction of 10% to the base fluid. This enhancement is up to 13.8% in the divergent mini-channel heat sink at Rebf = 295 and qh′′ = 3.21 W/cm2. Moreover, the divergent mini-channel heat sinks provide a higher Nusselt number along with lower pressure drop as compared with the parallel ones. Accordingly, the value of COP increases by diverging the mini-channel.

Electrocoalescence of water droplets in sunflower oil using a novel electrode geometry

Electrocoalescence is an energy-efficient and environmentally-friendly process for breaking water-in-oil emulsions. It has been used extensively in the oil and petroleum industries. However, the current technology requires long residence times, giving rise to bulky vessels for industrial scale operations and making it less attractive for offshore application. It is also highly desirable to develop compact devices for down-the-well use. In this study, the performance of a novel electrode geometry, a ladder-shaped set of electrodes through which the emulsion flows, is assessed for enhancing the electrocoalescence, hence providing the potential for a compact design. The electrodes are formed into a V shape, with the apex pointing towards the direction of flow. This configuration enables nesting a series of electrodes in a compact form. Furthermore, the water-in-oil emulsion flows through the electrodes rather than passing by them, thus maximizing the effect of the electric field for coalescence. The system under study uses dispersed water droplets in sunflower oil, flowing in a narrow rectangular duct through the electrodes, providing essentially a two-dimensional flowing stream. The performance of this design is investigated for different electrical parameters (i.e. electric field intensity, frequency and waveform), fluid physical properties (i.e. conductivity and water content) and residence time. Of the three types of electric field waveform (i.e. half-sinusoidal, square and sawtooth), sawtooth performs best at high conductivities. Experiments reveal the existence of optimal values of electric field intensity, electric field frequency, salt concentration and water concentration, where the coalescence efficiency is maximum for the current design. Numerical simulation of the electrocoalescence process is conducted to assess the influence of various geometric and process parameters on the coalescence mechanisms of the V-shape electrodes. The outcome of this work is potentially useful for optimizing the design of compact and efficient oil–water separators.

A model of emulsion plugging ability in sandpacks: Yield pressure drop and consistency parameter

In this study, a total of 20 sandpack flood tests, each with 11 different flow rates, were conducted to evaluate oil-in-water (O/W) emulsion plugging ability in sandpacks. Four conditions of emulsion flow in porous media were observed, identified, and discussed, in terms of the capillary number. A general model for the pressure drop versus flow rate based on the bi-viscosity model was developed from a comprehensive analysis of the experimental data. This model expresses that the flow of emulsion in porous media has two distinct mobility in porous media demarcated by a critical pressure drop. The inverse of the mobility is determined as consistency parameter and the critical pressure drop as the yield pressure drop. Effects of interfacial tension (IFT), emulsion quality, droplet size, emulsion slug size, and sandpack permeability on the yield pressure drop and consistency parameter were experimentally and numerically investigated. The newly proposed model has a good agreement between the predicted and experimental plugging pressure drop of emulsion. Besides giving guides on preparation of O/W emulsions and injection strategies in a specific oil reservoir, use of the proposed model can also help model reservoir scale O/W emulsion flow to reduce or shut-in the mobility in thief zones.

Boiling of disperse-phase droplets in a forced flow of emulsion in a minichannel

The paper presents the results of an experimental investigation of heat transfer during the boiling of disperse-phase droplets in a forced flow of an emulsion in a channel of circular section with an inside diameter of 1.1 mm. Investigations were conducted with water/silicone oil PMS-20 and n-pentane/glycerine emulsions stabilized by a surfactant and without additions of a surfactant. The obtained characteristics of heat transfer during the boiling of disperse-phase droplets of an emulsion are compared with similar characteristics for the single-phase convection of a dispersion medium. The heat flow from the channel wall being heated to the water/PMS-20 emulsion increases at the expense of the boiling of disperse-phase droplets and the convective heat transfer by a dispersion medium. Within a two-phase boiling pattern of an n-pentane/glycerine emulsion the effect of boiling droplets of n-pentane on the heat transfer characteristics has been revealed at high heating temperatures. The patterns of a two-phase flow have been visualized with the help of a high-speed camera. During the boiling in a flow of disperse-phase droplets of an emulsion stabilized by a surfactant there form stable patterns of a two-phase flow.

Experimental study of water-in-oil emulsion flow on wax deposition in subsea pipelines

Experiments were performed to simulate the deposition of wax in the flow of crude oil emulsions in subsea pipeline using a validated flow facility. Two crude samples and their respective formation water from two oil fields in southern Nigeria were used to synthetize two different emulsified crude oil samples (A and B). The trapping of the water globules in the wax deposits dominates the wax deposition rate initially but later the shear removal and the molecular diffusion dominate leading to decrease in the wax deposition rate. As the water (BS&W) composition in the emulsion increases from 10 to 40%, the pour point temperature (PPT) increases from 30 to 41 °C, and the viscosity increases from 40 mPas to 142 mPa at a crude oil temperature of 26 °C. The addition of 45 ppm of long chain acrylate ester co-polymer as pour point depressant depressed the dimensionless wax thickness by 37.5% and 34.3% for the blank emulsified crude oil A and B respectively. The effect of the commercial demulsifier to reduce the wax deposition rate was more successful in crude oil A reducing the wax dimensionless thickness by 58.9% and 43.0% when mixture of 25 ppm of the demulsifier and 45 ppm of long chain acrylate ester co-polymer were added to blank emulsified crude oil A and B respectively. The used demulsifier is more effective in crude oil A compared to crude oil B. Efforts should be made to study the effectiveness of different demulsifiers on each emulsified crude oil before their application for water separation.

Antimicrobial PHAs coatings for solid and porous tantalum implants

Biomaterial-associated infections (BAI) are the major cause of failure of indwelling medical devices. The risk of BAI can end dramatically in the surgical removal of the affected device. Therefore, a major effort must be undertaken to guarantee the permanence of the implant. In this regard, we have developed antimicrobial coatings for tantalum (Ta) implants, using polyhydroxyalkanoates (PHAs) as matrices for carrying an active principle. The dip-coating technique was successfully used for covering solid Ta discs. An original PHA emulsion flow process was developed for the coating of porous Ta structures, specially for the inner surfaces. The complete characterization of the biopolymer coatings, their antibacterial properties, toxicity and biointegration were analyzed. Thus, non-toxic, well-biointegrated homogeneous biopolymer coatings were attained, which showed antibacterial properties. By using biodegradable PHAs, the resulting drug delivery system assured the protection of Ta against bacterial infections for a period of time.

Numerical analysis of coolant flow in the grinding zone

The article presents results of research concerning computational fluid dynamics (CFD) of water oil emulsion in grinding zone during sharpening of hob cutter face surface. The numerical simulations made possible to determine the influence of different angular nozzle settings and nominal emulsion flow rate on the quantity of emulsion directly reaching the area of contact between the grinding wheel and the machined material. “SST k-ω” model, available in Ansys CFX program, was used in the numerical analysis; however, Kato and Launder’s modifications were used in the model. Experimental tests were carried out in order to verify results obtained on basis of the numerical simulations. The percentage rate of grinding wheel clogging was used as a verifying parameter. Analysis of the clogging made it possible to indirectly evaluate results of the numerical simulation. The clogging measurements were carried out using optical method by taking microscopic images of the grinding wheel active surface (GWAS), which were later analyzed using an image analysis program. As a result of the conducted numerical simulations, it was concluded that the greatest effectiveness of emulsion provision into the grinding zone was obtained when the nozzle was set at the smallest of the examined angles (30°) and greatest of the examined nominal flow rates (7 l/min). This conclusion was confirmed with results of experimental tests, where it was also observed that increasing the nominal flow rate over 5 l/min does not have significant influence on the amount of clogging on the grinding wheel active surface.