Foam Viscosity Research Articles

The Role of MWCNTs in Enhancing the Foam Stability and Rheological Behavior of Cement Pastes That Contain Air-Entraining and Superplasticizer Admixtures.

This research delves into the intricate dynamics between multi-walled carbon nanotubes (MWCNTs), air-entraining admixtures (AEAs), and a range of superplasticizers (SPs) in cementitious systems, shedding light on key aspects of construction material innovation. The focus is on how MWCNTs, AEAs, and specific SPs-namely, lignosulfonate (LS), polycarboxylate (PCE), and polyacrylate (PA)-influence the stability of foams and the viscosity and setting times of cement pastes. To assess the impacts of these components, we employed foam stability assessments, viscosity measurement techniques, electrical conductivity analysis, and evaluations of dispersion and setting times. Results indicate that MWCNTs enhance foam stability and viscosity, with the degree of improvement contingent on the type and concentration of SPs and the presence of AEAs. Notably, SPs, particularly PCE and PA, markedly influence the properties of cement paste, including increasing dispersion values and modulating setting times, especially when combined with MWCNTs and AEAs. The study concludes that strategically combining MWCNTs with specific SPs and AEAs alters the physical properties of cementitious materials significantly, underscoring the potential for customizing material design in the construction sector.

The effect of corrosion inhibitor chemistry on rheology and stability of CO2 and N2 acidic foam under harsh conditions

Utilization of CO2 foam in well-stimulation operations is a realistic practice to reduce carbon emissions by injecting CO2 into subsurface formations. The viscosity and stability of CO2 and N2 acidic foamed fluid is impacted by additives such as corrosion inhibitor and chelating agent and conditions such as pressure. In this study, the apparent foam viscosity was determined using a high pressure - high temperature foam rheometer at a temperature of 150 °C, pressure ranging from 1000–4000 psi, and different shear rates 100-2000 1/s. A foam analyzer was furthermore utilized to characterize foam properties such as foamability, foam stability, and bubble structures at 100 °C and 1000 psi. Different surfactants were used due to their ability to generate stable and viscous foam; Duomeen TTM, Ethoduomeen T13, Armovis VES, and the combination of Duomeen TTM and Armovis VES. Among all surfactants, Duomeen TTM provided the highest foam viscosity with CO2 at both low and high shear rate. Once the surfactant solution was mixed with 1.5 wt% of CI, the foam viscosity dropped sharply. However, the synergic surfactants (i.e., Duomeen TTM and Armovis VES) obtained the highest viscosity once mixed with CI. Also, the effect of CO2 and N2 at different pressures on the viscosity of generated foam was investigated. When the CO2 pressure was raised to 2000 psi, the viscosity of CO2 foam increased by 55% at both low and high shear. In comparison, the N2 foam viscosity increased by 12% at 100 1/s shear rate and by 32% at 1500 1/s. According to the findings, the influence of CI increased as the pH of the foam fluid declined, and thus reduced the foam viscosity. Finally, foam properties such as foamability, foam stability, and bubble structure were determined. N2 foam generated higher foam stability than CO2 foam. The findings of this study can help for a better understanding of the effect of corrosion inhibitor on CO2 and N2 foam viscosity at high temperature and pressure.

Characterizing Aqueous Foams by In Situ Viscosity Measurement in a Foam Column.

Foam characterization is essential in many applications of foams, such as cleaning, food processing, cosmetics, and oil production, due to these applications' diversified requirements. The standard characterization method, the foam column test, cannot provide sufficient information for in-depth studies. Hence, there have been many studies that incorporated different characterization methods into a standard test. It should be enlightening and feasible to measure the foam viscosity, which is both of practical and fundamental interest during the foam column test, but it has never been done before. Here, we demonstrate a method to characterize aqueous foams and their aging behaviors with the simultaneous measurement of foam viscosity and foam height. Using a vibration viscometer, we integrate foam column experiments with in situ foam viscosity measurements. We studied the correlation among the foam structure, foam height, and foam viscosity during the foam decay process. We found a drastic decrease in foam viscosity in the early foam decay, while the foam height remained unchanged, which is explained by coarsening. This method is much more sensitive and time-efficient than conventional foam-height-based methods by comparing the half-life. This method successfully characterizes the stability of foams made of various combinations of surfactants and gases.

Pipe rheology of wet aqueous application foams

Foam application of chemicals to the wet web is currently being developed for the paper and board industry. An important part of this work is to understand the rheology of the used application foams. Polyvinyl alcohol (PVOH) is widely used as a strength additive in paper and board, and it was the main surfactant in this study. The PVOH foam density varied between 100 kg/m3 and 300 kg/m3 and the dosage of PVOH varied between 0.5% and 6%. The foam viscosity and slip flow were determined with a pipe rheometer using three pipe diameters. The slip velocity was quantified by recording the foam motion in the vicinity of the wall of an acrylic pipe with a high-speed video camera. A measurement setup was also built for measuring the slip flow indirectly in opaque pipes. General formulas for the foam viscosity and slip flow, based on several physical quantities describing both the foam and the base liquid, were obtained using dimensional analysis. Specifically, dimensionless shear stress and dimensionless wall shear stress were found to be proportional to certain powers of the capillary number and slip capillary number, respectively. The contribution of the slip flow to the total flow rate was significant, especially with lower flow rates when most of the volumetric flow was due to the slip. In the literature, many papers have suggested that there is no slip flow in steel pipes. Our results suggest that this is due to the high pipe roughness used in those works. In our measurements, the slip velocity of a smooth-walled steel pipe was equal to the slip in an acrylic pipe. The obtained viscosity and slip models form a solid basis for developing and running various industrial processes including foam application processes. For new foam recipes, quite a small number of rheological measurements are needed to determine the model parameters.

Effects of Different Types of Stabilizers on the Properties of Foam Detergent Used for Radioactive Surface Contamination.

Compared with high-pressure water and reagent washing decontamination, foam decontamination has a promising application due to its ability to significantly reduce the volume of radioactive waste liquids and effectively decontaminate the inner surface of the pipes, the interior of the large cavities, and the vertical walls. However, the foam is less stable, leading to a low decontamination rate. Currently, three main types of stabilizers with different stabilizing mechanisms, namely nanoparticles, polymers, and cosurfactants, are used to improve foam stability and thus increase the decontamination rate. Nanosilica (NS), xanthan gum (XG), and n-tetradecanol (TD) were used as typical representatives of nanoparticles, polymers, and cosurfactants, respectively, to improve the stability of the foam detergent with pH < 2 and chelating agents. The differences in the effects of these three types of stabilizers on foam properties were investigated. Although NS, XG, and TD all increase the half-life of the foam from 7.2 min to about 40 min, the concentration of TD is much lower than that of NS and XG in the foaming solution, and TD foaming solution has the highest foaming ratio. Moreover, TD can markedly lower the surface tension, resulting in a significant reduction of the wetting contact angle on the surfaces of glass, ceramic tile, stainless steel, and paint, while NS and XG cannot signally change the surface tension and have no obvious effect on the wetting contact angle. At low shear rates, TD can increase the apparent viscosity of foam by two orders of magnitude, and the wall-hanging time of the foam on the vertical wall is more than 30 min. In contrast, NS and XG cause a limited increase in the apparent viscosity of the foam, and the wall-hanging times are both less than 5 min. In addition, TD foaming solution has excellent storage stability, and the storage time has no obvious effect on the performance of the foam. And after only three days of storage, NS undergoes severe agglomeration and precipitation in the foaming solution, resulting in a complete loss of the stabilizing effect. After 90 days of storage, the half-life of XG foam decreases by 26%. For simulated radioactive uranium contamination on both horizontal and vertical surfaces, TD can significantly improve the decontamination rate, especially for vertical surfaces, where TD can increase the single decontamination rate by more than 50%.

Development of An Eco-Shampoo Formulation Using Local Environmental Plant Extracts for Healthy Hair as an Effort to Increase the Potential of Environmental Resources

This research aims to develop an eco-friendly shampoo formulation (Eco-Shampoo) by adding local environmental plant extracts for hair health. This research method is a quasi-experimental development of existing shampoo formulations (base formulations) by adding local plant extracts such as aloe vera (Aloe vera L.) and lemongrass oil (Cymbopogon citratus) in three formulations. The resulting shampoo products were then carried out two evaluations, namely the stability test (organoleptic test), foam height observation, viscosity test, pH test, and preference test (hedonic test) by consumers to determine the feasibility and effectiveness of using shampoo. After a storage period of 2 days showed a Stability test, slightly changed color, constant odor, and texture did not change and the pH value was between 5.5 - 6.5. The smear test on the back of the hand and the skin behind the ear did not show skin irritation, whereas the hedonic test, 10 consumers stated that the color was like, the smell was stated like, and the texture was stated quietly. Aloe vera fraction and lemongrass oil can be formulated as a shampoo preparation to maintain hair fertility as well as an anti-dandruff shampoo.

Investigation of amine-based surfactants for foamed acid stimulation at high temperature, pressure, and salinity

This research investigated the rheology of foamed acid using different amine-based surfactants including Duomeen TTM (TTM), Ethoduomeen T/13 (T/13), Ethomeen C/12 (C/12), and Armogel O at 150 °C and 1000 psi using a modified (high pressure-high temperature) HPHT foam rheometer. The study was conducted in high-salinity water as a replacement for freshwater to promote sustainability. Foam properties such as foam stability, foamability, foam structure, bubble count, and size were investigated through a novel HPHT foam analyzer under different conditions; (23 °C, 14.7 psi) and (120 °C, 1000 psi). The obtained results showed that Duomeen TTM exhibited the highest foam viscosity as a result of the generation of stable wormlike micelles at 150 °C and 1000 psi. Additionally, both Duomeen and Ethoduomeen T/13 displayed stable foam viscosity at a steady shear rate of 500 1/s for 8 h. The temperature has a major impact on foam viscosity; as the temperature raised from 100 °C to 150 °C, the apparent foam viscosity dropped by 36.9% at 500 1/s and at least by 26.5% at 2000 1/s. The outcomes of the HPHT foam analyzer showed that the surfactants, except for Ethomeen C/12, showed poor foamability under ambient conditions. However, at HPHT, high bubbles count was generated with a uniformly fine texture. For Duomeen TTM, the initial bubble count increased, almost by 76.7%, indicating better foamability at HPHT. Additionally, the foam half-life time of all surfactants except for Duomeen TTM decreased sharply once pressure and temperature increased. The stability decreased by 9.7% for Duomeen TTM, 57.7% for Armogel O, 69.1% for Ethoduomeen T/13, and 85.7% for Ethomeen C/12 as compared to ambient conditions. This paper offers a wide-ranging understanding of amine-based surfactants on stimulating foam viscosity and stability at HPHT.

Effect of Whey Protein Isolate-Meniran Extract (Phyllantus niruri L.,) Eencapsulation Using Casein Hydrolysate on Foam, Optical Microscopy, Particle Size, and Viscosity

The purpose of this study was to determine the effect of whey protein isolate (WPI)-extract of meniran (Phyllanthus niruri L.) encapsulation using casein hydrolyzate on foam overrun, optical microscopy, particle size and viscosity. The materials used was whey protein isolate, an extract of meniran (Phyllanthus niruri L.) encapsulated using casein hydrolyzate. The method used was a completely randomized design (CRD) with 5 treatments of casein hydrolyzed as encapsulation material, 0%, 2%, 4%, 6% and 8%, namely P0, P1, P2, P3 and P4 repectively, with 3 replications. The variables observed were foam overrun, particle size, and viscosity which were analyzed using analysis of variances (ANOVA). If there is a significant or very significant difference, analysis will be continued with the DMRT (Duncan Multiple Range Test). Variable of optical microscopy was analyzed descriptively. The results showed that whey protein isolate-meniran extract encapsulation using casein hydrolyzate gave a very significant difference (P&lt;0.01) on in viscosity and foam overrun but did not give significant difference (P&gt;0.05) on particle size. The average foam overrun value was 325% - 400%, the viscosity was 0.985 cP - 1.015 cP, the particle size was 0.8944 nm - 1.5031 nm, and optical microscopy showed that the most abundant distribution and amount of foam was observed in P4, namely whey protein isolate-meniran extract encapsulated with 8% casein hydrolyzate. Along with the addition of casein hydrolyzate with different concentrations (2%, 4%, 6%, 8%), the distribution and shape of the foam became more even and uniform. The conclusion of this study was that the addition of 6% casein hydrolyzate on the encapsulation effect of whey protein isolate-meniran extract was able to maintain the physical properties of WPI-meniran extract on viscosity, optimal particle size, foam overrun, and optical microscopy with a shape, uniform foam distribution and lamella tend to be thick.

Synthesis and flotation performance of a novel low-foam viscous cationic collector based on hematite reverse flotation desilication system

Traditional cationic collectors generally exist some disadvantages, such as high foam viscosity and difficulty in defoaming, which worsening the flotation separation effect. Herein, a novel cationic collector-dodecyl trihydroxyethyl ammonium bromide (DTDAB) with low-foam viscous was synthesized to optimize the reverse flotation system of hematite ore, which was achieved by introducing three hydroxyethyl groups into the nitrogen atoms of dodecyl trimethyl ammonium bromide (DTAB). The analysis of foam collapse performance indicated that the introduction of hydroxyl groups into hydrophilic head groups of DTAB reduced the interface surface tension and bubble coalescence, which were consistent with the design expectations. Meanwhile, flotation behaviors were systematically studied, and the results showed that the concentrates with 63.89 % total iron (TFe) grade and 89.27 % total iron recovery was obtained at pH 6.81, when the concentration of DTDAB and starch was 20 mg/L and 5 mg/L, respectively. Besides, the possible flotation mechanism was further studied by means of contact angle, Atomic force microscope (AFM), Fourier transforming infrared spectra (FT-IR), X ray photoelectron spectroscopy (XPS), and Density functional theory (DFT) calculation. The results comfirmed that the adsorption between DTDAB and quartz was caused by electrostatic force and hydrogen bonding affinity. In conclusion, it can be confirmed that the novel cationic collector DTDAB with low-foam viscous has the potential for the hematite reverse flotation desilication.

The effect of rock permeability and pore structure on foam in carbonate rocks

Foam is considered a successful method for providing conformance control during enhanced oil recovery. It helps reduce gravity segregation, viscous fingering, and minimizes injected fluid loss into high permeability zones. Foam rheology has been studied and well understood in sandstones but its behavior in carbonate rocks is not well defined. This study aims to quantify the impact of pore properties represented by permeability, pore throat size (dT), pore body size (dB) and aspect ratio (R) on foam rheology in carbonate rocks. The results are contrasted with foam rheology in natural sandstone rocks. The studied carbonates possess complex pore structures, with bimodal distributions of pore throat and pore body sizes. Pore properties were shown to affect the magnitude of foam viscosity (μa)-foam quality relationship, but the observed trend is unchanged in different rocks. μa was found to linearly correlate with (dT2) and permeability. It was shown to increase exponentially with dB with a marked increase at dB > 30 μm. All the carbonates had aspect ratios R ≫ 2.5 indicating plentiful foam germination sites. As a result, the aspect ratio does not correlate strongly with μa. Pore structure properties were shown to have a strong impact on the μa-shear rate (γ̇a) relationship, by directly impacting the magnitude of both μa and γ̇a, and also by influencing the foam texture. Finally, pore properties were shown to impact factors governing foam transient behavior. Rocks with smaller (dT) are shown to have weaker foam generation and propagation, as well as a larger specific surface area leading to larger dynamic adsorption. Overall, the results of this work indicate that the successful implementation of foam for mobility control in carbonate reservoirs will depend on a good understanding of the rock pore structure.

Experimental Study and Molecular Simulation of the Effect of Temperature on the Stability of Surfactant Foam

Temperature changes in CO2 foam-fracturing construction can easily affect surfactant foam stability. To investigate the effect of temperature on the foam stability of different types of surfactants, this study measured the foam half-life and viscosity of four typical surfactants, CTAB, LAS-30, HSB1214, and TX-10, using a novel self-designed and built foam performance measurement device. The effects of temperature on foam half-life and viscosity were studied. The results show that as the temperature increased, the half-life shortened, and the viscosity of the liquid phase decreased, which led to a decrease in foam stability. Moreover, using Materials Studio, a type of molecular simulation software, an interfacial model of the foam film was constructed to calculate the IFE and the self-diffusion coefficient of water molecules at 300 ps after the equilibrium of the foam system to investigate the mechanism of temperature influence on the stability of the foam. The results show that, for CTAB, LAS-30, HSB1214, and TX-10, the temperature increases from 15 °C to 45 °C, the IFE is enhanced by −50.05%, −59.10%, −64.21%, and −44.26%, respectively, the interfacial system changes from a low-energy state to a high-energy state, and the interfacial stability decreases. Meanwhile, Dwater increased 1.10-fold, 0.78-fold, 1.43-fold, and 0.64-fold, respectively, which accelerated the diffusion and migration of water molecules, weakened the intermolecular forces, and accelerated the instability of the foam system.

Experimental Study on the Effects of New Foam on the Improvement of Sandy Soil for Earth Pressure Balance Shield

In this paper, starting from the foaming amount, half-life and other indicators, the surfactant with excellent performance is optimized, and the optimal compound ratio and appropriate foam stabilizer, viscosity enhancer, and additives are studied. A new type of foam agent formula for the EPB shield is developed. The performance of the new foam agent is compared with that of domestic foam and imported foam from the aspects of foaming rate, stability, micromorphology and temperature resistance, which verifies that it meets the parameter requirements and advantages of a foam agent for shield tunneling. Then, by means of laboratory tests, such as the mixing test, friction coefficient test, adhesion resistance test, slump test and direct shear test, the improvement effect of the new foam agent is compared with existing foam agent products at home and abroad, and the improvement effect of the new foam agent on soil is evaluated. The formulation of the new foam agent is as follows: 1.6% sodium dodecyl sulfate (SDS) + 8% dodecyl dimethyl betaine (BS-12) + 7% dodecanol + 0.06% guar gum + 0.6% ammonium chloride. The foaming rate, stability, microstructure and temperature resistance of new foam meet the requirements of shield construction. New foam, imported foam and domestic foam have advantages in sand and soil improvement experiments, but from an economic point of view, the new type of bubble is better than the other two. A new type of shield foam agent is prepared to meet the needs of construction. There is a big advantage in terms of price.

Foam Flow Model of Municipal Solid Waste and Its Application in Landfill Gas Pressure Prediction

Foam, as a group of disconnected gas bubbles wrapped with liquid film, also exists in municipal solid waste (MSW) landfills. In this study, a foam flow model in MSW is established, in which the population balance equation is adopted to calculate the dynamic process of foam generation, bursting, and transport. The status of foam is characterized using the number density, which is defined as the number of bubbles per unit volume of pore. The relative permeability and viscosity of foam are corrected according to its number density. Then, the proposed model is verified through the foam displacement experiment conducted in an MSW column. The foam flow model can accurately simulate the transient change of pressure drop and liquid saturation during foam displacement. The values of coefficients of foam generation and bursting rates are fitted to be suitable for MSW. Finally, the foam flow model is applied to predict the gas pressure development in an MSW landfill. Foam is able to maintain the landfill gas pressure at a high value even for aged MSW with low gas generation rate. The S-shaped curve of gas pressure versus depth suggests that the foam flow model is capable of simulating the phenomenon of high gas pressure accumulated in the deep layer of landfills because it takes into account the nonuniform distribution of foam number density. The advantage of the foam flow model over the gas flow model is discussed with respect to landfill gas pressure prediction.

Flow rheology of light foams generated from aqueous solutions of polyvinyl alcohol

Recent studies have shown that foam-assisted application of additives into a wet web has advantages over the conventional way of adding the chemicals into the pulp suspension before forming, e.g., increased mechanical retention as well as high dosage giving increased wet strength without impairing the sheet uniformity. To engineer processes utilizing this new technology, the complex flow behavior of applied foams must be quantified. At the minimum, the foam viscosity and the slip velocity at the solid surfaces need to be known to build practical models that can be used in analyzing and upscaling unit processes of the foam-assisted application. In this study, the rheological behavior was quantified for foams having polyvinyl alcohol (PVOH), a widely used strength additive chemical, as the surfactant. The foam density was varied between 100 g/L and 300 g/L, and the concentration of the PVOH solution was varied between 0.5% and 6.0% (w/w). The foams were generated with a commercial foam generator, and the rheological properties of the foams were measured by using a horizontal pipe bank. At the outlet from the generator, the volumetric flow rate, the absolute pressure, and the bubble size distribution of the foam were measured. In the measurement pipe section, the viscous pressure gradient and the slip velocity were measured, after which the foam was discharged to ambient air pressure. The viscosity and the dynamic surface tension of the PVOH solutions were quantified with commercial laboratory devices. In the viscosity analysis, the apparent shear rate was calculated from the volumetric flow rate, and the resulting apparent viscosity was translated to real material viscosity data by applying the Weissenberg-Rabinowitsch correction. The results indicated that PVOH foams can be described with high accuracy as shear-thinning power-law fluids where the detailed behavior depends on the foam density and the PVOH concentration. Slip flow, as usual, increased with increasing wall shear stress, but it was also dependent on the PVOH concentration, the air content, and the bubble size. For both the foam viscosity and the slip flow, a correlation was found that described the quantitative behavior of all the studied foams with good accuracy.

Stable CO2/water foam stabilized by dilute surface‐modified nanoparticles and cationic surfactant at high temperature and salinity

AbstractCO2 enhanced oil recovery and storage could see widespread deployment as decarbonization efforts accelerate to meet climate goals. CO2 is more efficiently distributed underground as a viscous foam than as pure CO2; however, most reported CO2 foams are unstable at harsh reservoir conditions (22 wt% brine, 2200 psi, and 80°C). We hypothesize that silica nanoparticles (NP) grafted with (3‐trimethoxysilylpropyl)diethylenetriamine ligands (N3), to improve colloidal stability, and dimethoxydimethylsilane ligands (DM), to improve CO2‐phillicity, combined with the cationic surfactant N1‐alkyl‐N3, N3‐dimethylpropane‐1,3‐diamine (RCADA), will develop viscous, stable CO2 foams at reservoir conditions. We grafted NP with N3 and DM ligands. We verified NP stability at reservoir conditions with measurements of zeta potential, amine titration curves, and NP diameter. We measured NP water contact angles (θw) at the water–air and water–liquid CO2 interfaces. In a high‐temperature, high‐pressure flow apparatus, we calculated the viscosity of CO2 foams across a beadpack and determined static foam stability with microscope observations. Modified NP were colloidally stable at reservoir conditions for 4 weeks, and had higher θw in liquid CO2 than in air. Addition of at least 0.5 μmol/m2 DM silane (0.5DM) greatly improved foam stability. RCADA‐only foam coarsening rates (dDSM3/dt) decreased 16–17× after adding 1 wt/vol% 8N3 + 1.5DM NP, and 5–10× with a 0.1–1 vol/vol% increase in RCADA concentration (with or without NP). 1 vol/vol% RCADA foam exhibited coarsening rates of 900 and 2400 μm3/min with 1 and 0.2 wt/vol% 8N3 + 1.5DM NP, respectively. These results demonstrate impressive foam stabilities at harsh reservoir conditions.

Synthesis of in situ Generated Cu−CNT Hybrid Nanofluid and the Study of Their Thermo‐physical Properties

AbstractIn recent years, numerous investigations have been carried out in heat transfer applications for CNT nanofluid as it possesses a high thermal conductivity compared to conventional fluids. Hydrophobicity of CNT poses a challenge to disperse CNT in polar basefluid. Surfactants can solve this issue up to a certain extent only but have some associated disadvantages such as foam formation, stickiness and viscosity enhancement responsible for an increase in power required to pump Nanofluid in heat transfer devices. This work presents preparation of a hybrid nanofluid as an alternative. Cu−CNT hybrid nanoparticles were generated in this research using in‐situ preparation of Cu nanoparticles in the presence of CNT and dispersion in double distilled water without addition of surfactant to produce a stable nanofluid. FESEM with EDX confirms copper nanoparticles present on outer surface of MWCNT and Raman spectroscopy confirmed the covalent functionalization. Spectral analysis, Zeta potential, and DLS were used to evaluate the dispersibility of Cu−CNT hybrid nanofluid. The results showed that the samples were extremely stable, with maximum stability of about 168 days. XRD pattern of Cu−CNT hybrid nanoparticles confirmed the existence of Cu and CNT. Nanofluid demonstrated a minor increase in density and viscosity compared to basefluid water due to addition of nanoparticles. An increase in thermal conductivity was also observed, which is critical for heat transfer applications.

Assessment of foam generation and stabilization in the presence of crude oil using a microfluidics system

The use of foams is a promising technique to overcome gas mobility challenges in petroleum reservoirs. Foam reduces the gas mobility by increasing the gas apparent viscosity and reducing its relative permeability. A major challenge facing foam application in reservoirs is its long-term stability. Foam effectiveness and stability depends on several factors and will typically diminish over time due to degradation as well as the foam-rock-oil interactions. In this study, the effect of crude oil on CO2-foam stability and mobility will be investigated using in-house build microfluidics system developed for rapid prescreening of chemical formulations. Two-phase flow emulsification test (oil-surfactant solutions) and dynamic foam tests (in the absence and presence of crude oil) were conducted to perform a comparative assessment for different surfactant solutions. A microfluidics device was used to evaluate the foam strength in the presence and absence of crude oil. The assessment was conducted using five surfactant formulations and different oil fractions. The role of foam quality (volume of gas/total volume) on foam stability was also addressed in this study. The mobility reduction factor (MRF) for CO2-foam was measured in the absence and presence of crude oil using high salinity water and at elevated temperatures. The results indicated that foam stability has an inverse relationship with the amount of crude oil. Crude oil has a detrimental effect on foams, and foam stability decreased as the amount of crude oil was increased. Depending on the surfactant type, the existence of crude oil in porous media, even at very low concentrations of 5% can significantly impact the foam stability and strength. The oil can act as an antifoaming agent. It enters the thin aqueous film and destabilizes it. This resulted in a lower foam viscosity and less stable foams. Thus, the CO2 MRF dropped significantly in the presence of higher oil fractions. This study also demonstrated that in-house assembled microfluidics system allows for a rapid and cost-efficient screening of formulations.

Rheology of oil-based nitrogen foam at shallow reservoir conditions: Experiment and evaluation

Exhibiting as a combination of viscous, elastic, and plastic behavior, rheology is a branch of physics and is majorly concerned with continuum mechanics for flow characterizations, particularly non-Newtonian flow like foam. However, most existing studies of foam rheology are primarily focused on water-based foam, while oil-based foam rheology lacks adequate understanding, plus few comprehensive experimental analyses have been done. This study, for the first time, investigates the rheological behavior of oil-based nitrogen foam with full foam quality and shallow reservoir conditions through a newly-designed visualized capillary rheometer. Basically, the effects of foam quality and shear rate on foam morphology and apparent viscosity were elucidated, and the foam rheology at different temperatures and pressures was evaluated. More specifically, with increasing shear rate, the apparent viscosity of nitrogen foam decreases in a concave-down parabola pattern. With the foam quality of 86 %, the apparent viscosity of the foam flow is found to reach its maximum value, 58.4 mPa·s, at the flow rate of 4 mL/min, temperature of 25 °C and pressure of 5 MPa. The foam flow gradually becomes uniform and dense and the apparent viscosity elevates with increasing foam quality up to 86 %. After that, the foam flow tends to be slug flow and its stability becomes worse with linearly-decreasing apparent viscosity. With increasing pressure, the apparent viscosity and consistency coefficient increase, which result in the increase of rheological index and decrease of non-Newtonian property. The temperature effects on the foam flow are absolutely opposite but stronger in comparison to pressure effects as aforementioned. In addition, the rheological equations of nitrogen foam are determined by fitting the consistency coefficient and rheological index with foam quality. Overall, thorough investigations of the rheology of oil-based nitrogen foam would be of great importance for foam theory and practice.

Effects of different gases on the performance of foams stabilized by Cocamidopropyl betaine surfactant and silica nanoparticles: A comparative experimental study

Application of CO 2 gas in foam enhanced oil recovery (EOR) processes has emerged as a win-win strategy for achieving higher oil recovery factor and reducing greenhouse gas emission, which can significantly help the protection of the ozone layer from depletion. However, lower stability of CO 2 -foam, as compared to the N 2 - and CH 4 -foams, has tempted us to examine combinations of CO 2 with these gases to not only improve the stability of the produced foam but also have CO 2 as the gaseous phase of the foam. In this study, we investigated the effect of different gases and the mixture thereof on the performance of foams in EOR while the aqueous phase of foams is a constant mixture of Cocamidopropyl betaine surfactant (0.03 wt %) and silica nanoparticle (0.1 wt%). To this end, seven different gases, including N 2 , CO 2 , CH 4 , 80% N 2 + 20% CO 2 , 80% CH 4 + 20% CO 2 , 50% CH 4 + 50% CO 2 , 50% N 2 + 50% CO 2 were used as the gases phase for foam generation, and the performance of the produced foams were examined through the following experiments: bulk foam stability tests, apparent foam viscosity measurements, and core flooding tests. The results of foam stability tests showed that half-life time for the CO 2 -, CH 4 -, and N 2 -foams are 13.5, 17.0, and 44.0 min, respectively. Also, as revealed from apparent viscosity measurements, the N 2 - and 80% N 2 +20% CO 2 foams have higher apparent foam viscosity values followed by 50% N 2 +50% CO 2 foam. Furthermore, we showed that a combination of 80% N 2 + 20% CO 2 as the gaseous phase for foam generation could not only improve CO 2 -foam stability, as compared to other foams, but also can substantially increase ultimate oil recovery (56.6 %OOIP), even more than that for N 2 foam (48.6 %OOIP), obtained from core flooding experiments.

The Impact of Green Chelating Agent and Corrosion Inhibitor on Foam Rheology and Stability at High Temperature, Pressure, and Salinity

Summary This research fills the gap in understanding the impact of corrosion inhibitors (CIs) and a chelating agent on the rheology and stability of foam under harsh conditions. In this regard, a modified high-pressure, high-temperature (HPHT) foam rheometer and HPHT foam analyzer were used to investigate foam rheology and stability at 1,000 psi and 120 to 150°C with carbon dioxide (CO2) in the gas phase. Surfactant screening showed that Duomeen TTM and Armovis are thermally stable at high temperature and high water salinity and thus were used in this study. The liquid phase generally contained produced water (PW) (total dissolved solids ~ 24,611 ppm), 15 wt% chelating agent [L-glutamic acid-N, N-diacetic acid (GLDA)], and 1 wt% surfactant with and without a CI. First, we screened the viscosity and stability of Duomeen TTM and Armovis; the results showed that Duomeen TTM has a higher viscosity (at least by 82%) at a low shear rate, but both have similar viscosity at a higher shear rate. However, Armovis produced more stable foam. Once the GLDA was added to the Duomeen TTM solution, the viscosity increased significantly by 135% at a high shear rate (1,000–1,500). For the Armovis system, the viscosity improved by 77% and 68% at the low and high shear rates by adding GLDA. Additionally, foam stability was improved remarkably in both systems; half-life time almost doubled. Finally, we reported the effect of CI on the fluid systems, showing it considerably reduced the foam viscosity and stability. It reduced the half-life of the Armovis system by 79.4% and hindered the generation of foam for the Duomeen TTM system. A detailed discussion of foam properties, such as foamability, bubble count, and bubble radius, is provided. This study provides a wide-ranging understanding of additives’ impact on stimulating foam stability at HPHT.