Foaming Solution Research Articles

Nozzle diameter and expansion ratio of compressed air foam system

Variations of nozzles are studied for Compressed Air Foam Systems (CAFS). The CAFS is a self-contained fire suppression system with the capability of injecting compressed air into the foam solution to create a dense mist. Even though this type of foam has a tighter, denser bubble structure that allows it to adhere to vertical and horizontal surfaces and penetrate the fire more deeply before the bubbles burst, thereby making it more effective, the nozzle of CAFS is weak. The experimental study has been done in order to find the expansion ratio of the nozzle. Four sizes of diameter nozzles are 5 mm, 10 mm, and 20 mm, and three holes are 20 mm. Nozzle diameter size has a correlation with bubble size. The highest expansion ratio is found in the nozzle with three holes 20 mm in diameter. It is followed by a nozzle with a 20 mm diameter, then a 10 mm diameter. The last finding is a nozzle with five diameters. The other founding is the linear correlation between nozzle diameter size and bubble size. But it is on the other way than the correlation between nozzle diameter and bubble size. The shorter the nozzle diameter, the faster the fire extinguishing time.

Development and characterization of thermo-sensitive biomass-based smart foam drainage gas recovery treatment agent

Wellbore fluid accumulation is a common issue associated with gas wells, yet traditional foam drainage gas production technology is hindered by high costs, large amounts of defoamer, and insufficient environmental performance. A biomass polymer with temperature-sensitive response characteristics was developed to improve the efficiency of foam drainage gas recovery technology. Additionally, an intelligent foam solution was prepared that was combined with cationic surfactants. The results of thermo-sensitive performance tests indicate that raising temperature increases the particle size of the copolymer, decreases the surface tension of the solution, increases turbidity, and decreases viscosity. The comprehensive performance test results demonstrate that when the ambient temperature falls below the lower critical solution temperature (LCST), the foam height of the smart foaming solution is substantially higher than that of surfactant solution for 3 min, up to 57 mm. Smart foaming solution has thermo-sensitive defoaming performance, when the ambient temperature is greater than the LCST, it can quickly defoam within 3 min. After 5 thermal cycles, the foaming height is still as high as 65.6 mm. Its corrosion inhibition rate reaches an optimal value of 45.32% at 50 °C. With its superior temperature resistance, the scale inhibition rate of this smart foam solution remains greater than 40% at 90 °C. Our work provides a basis for the research and development of functional agents and improves the efficiency of foam drainage gas production.

Rheological properties of solutions of fluorine-free foams

NFPA and EN design standards for systems of firefighting foams suggest applying the Hazen-Williams formula to predict the pressure drop associated with pumping of foam solutions. The empirical Hazen-Williams formula pertains only to water at room temperature, which is a Newtonian fluid. In this contribution, we examine the rheology of six foam solutions, comprising four alcohol-resistant fluorine-free foams (AR-FfreeF), one FfreeF and one AR-AFFF (alcohol-resistant aqueous film-forming foam). We reveal that two solutions are weak gel-like viscoelastic solids, one is a viscoelastic solid displaying high elasticity, and three are viscoelastic fluids. All solutions exhibit significant shear thinning. We associate these non-Newtonian properties of the solutions mainly with the presence of polysaccharides in their chemical make-up. The pressure-drop calculations suggest that the Hazen-Williams formula should not be used for solutions of FfreeF that display semi-dilute entangled and concentrated abundance of polysaccharides. However, we also demonstrate that, the Hazen-Williams formula approximates the results of the formulation of the AR-AFFF, but only in the turbulent regime. Finally, we flag that premixes of AR-FfreeF may display aging on the time scale of weeks, suggesting the inclusion of this property in foam standards.

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%.

Effect of liquid fuel on foamability and foam stability of mixtures of fluorocarbon and hydrocarbon surfactants

The oil resistivity of aqueous foam is a significant property in many industrial fields. This work aims at studying on oil resistivity of foams generated by mixtures of fluorocarbon and hydrocarbon surfactants, the critical components of firefighting foams. Four kinds of foam solutions were prepared to contain a short-chain fluorocarbon surfactant (FS-50) and four hydrocarbon surfactants with different ionic types, including anionic (SDS), cationic (CTAB), zwitterionic (CAD-40), and nonionic (APG-0810). The effects of the typical liquid fuel (n-heptane) on solution properties, foamability, foam stability, and film stability were studied deeply. The results show that foamability and foam stability were significantly influenced by the addition of n-heptane. The addition of n-heptane leads to significant decrease in foamability of all four foam solutions. The foam volume decay and drainage of all four solutions were accelerated under the action of n-heptane. The film stability of all four solutions decreased upon the presence of n-heptane. The mixture of APG-0810/FS-50 showed the best ability to inhibit liquid fuel. The study can promote the use of mixtures of hydrocarbon and fluorocarbon surfactants in the development of firefighting foams used to extinct liquid fuel fires.

Experimental investigation of drilling cutting transport using foam

This study investigates the stability of foam in drilling fluid, focusing on the impact of surfactant (sodium dodecyl sulfate) and hydroxyethyl cellulose polymer. The research analyzes various influential factors and examines three rock types (carbonate, limestone, and sandstone) commonly encountered in drilling operations. Additionally, the study explores the behavior of drilling cuttings from light, medium, and heavy reservoir oil types (Bangestan, Asmari, and Soroush) found in Iranian oil fields. The influence of salinity, specifically divalent (calcium) and monovalent salts (sodium), on foam performance is also investigated.Experimental findings reveal that higher concentrations of critical micelle concentration do not significantly affect foam stability, but are used in preparing the foaming solution. Furthermore, different polymer concentrations (ranging from 0% to 0.5%) enhance foam stability, except at a concentration of 0.5% where foam formation is impeded. Interestingly, the transfer of more stable foam and a greater volume of cuttings to the surface is facilitated in sandstone layers. The presence of heavy oil significantly impacts the rate of cuttings transfer compared to lighter oils.

Effect of sodium alginate and polyvinyl alcohol polymers on the foaming performance of dodecyl dimethyl betaine solutions

The zwitterionic ionic surfactant dodecyl dimethyl betaine (BS-12) exhibits both positive and negative charges simultaneously, and the charged nature of the incorporated polymer may impact the performance of BS-12. In this paper, the characteristics of anionic composite foam solutions formed by the electrostatic interaction between -COO- of sodium alginate (SA) and -NH+ of BS-12, as well as the zwitterionic composite foam solutions formed by hydrogen bonding between polyvinyl alcohol (PVA) and BS-12, were utilized to investigate the effects of SA and PVA, respectively, as stabilizers on the foam properties of their solutions. The results showed that the pure BS-12 solution exhibited excellent foaming performance, while the defoaming rate after 5 min reached over 90%. In both types of polymer-enhanced foam systems, the addition of PVA resulted in a decrease in foaming performance for BS-12 and was only effective in improving the foam stability of BS-12 at high concentrations of the foam solution. In contrast, the addition of SA exhibited a positive synergistic effect on the composite system BS-12 foam solution, with an optimal foaming concentration of 1 wt% BS-12 and 0.2 wt% SA. However, its impact on the stability performance of low-concentration BS-12 foam solutions was more significant than that of high-concentration ones. Therefore, the type and concentration of polymer should be strictly controlled in the practical application of BS-12, and we suggest using anionic polymers with low concentrations to improve the foaming and foam stability of BS-12 in practical application.

A systematic investigation of the relationship between properties of bulk foam and foam in porous media

Bulk foam analysis (static test) is simple and fast, which makes it a cost-effective method for screening and ranking hundreds of surfactants being considered for foam applications. Coreflood tests (dynamic test) can also be used, but it is quite laborious and costly. However, previous reports show that ranking based on static tests sometimes differs from ranking based on dynamic tests. To date, the reason for such a discrepancy is not well understood. Some believe that it may be due to faulty experimental design while some others believe that there is no discrepancy if the right foam performance indices are used to describe and compare the results from both methods. For the first time, this study reports a systematic series of static tests conducted on different foaming solutions (with surfactant concentration ranging from 0.025 to 5 wt%) and duplicated in dynamic tests using the same core sample for all the surfactant solutions. The dynamic test was also repeated on three different rocks of a wide permeability range (26–5000 mD) for each of the surfactant solutions. Unlike previous studies, here multiple dynamic foam indices (limiting capillary pressure, apparent viscosity, trapped foam, and trapped to mobile foam ratio) were measured and compared with the performance indices measured from the static tests (foam texture and foam half-life). Dynamic tests were in total agreement with static tests for all the foam formulations. However, it was observed that the pore size of the base filter disk used in the static foam analyzer can be a potential source of conflicting results when comparing with dynamic test. This is because a threshold pore size exists above which some foam properties (apparent viscosity and trapped foam) significantly decreased compared to the properties before that threshold. Foam limiting capillary pressure is the only foam property that does not show such a trend. It also appears that such threshold occurs above a certain surfactant concentration (0.025 wt%). Apparently, it becomes imperative that the pore size of the filter disk used in the static test and the porous medium used in dynamic tests must be on the same side of the threshold point, otherwise there may be disparity in their results. The threshold surfactant concentration should also be determined. The role of these two factors (pore size and surfactant concentration) requires further investigation.

Salt-blocking three-dimensional Janus evaporator with superwettability gradient for efficient and stable solar desalination

Solar interfacial steam power generation is a prospective method for seawater desalination. In this work, a salt-blocking three-dimensional (3D) Janus evaporator with a superhydrophobic to superhydrophilic gradient was fabricated by spraying a composite dispersion of multi-walled carbon nanotubes/polydimethylsiloxane (CNTs/PDMS) onto the top side of a polyurethane (PU) foam and polyvinyl alcohol (PVA) solution onto the bottom side. The CNTs/PDMS composite dispersion with nanostructured CNTs and low surface energy PDMS combined with the porous structure of the PU foam rendered the top side superhydrophobic. Therefore, a layer suitable for photothermal conversion was obtained. The hydrophilic PVA combined with the porous structure of the foam rendered the bottom side superhydrophilic, facilitating water absorption and transportation. The asymmetric wettability gradient of the CNTs/PDMS-PU-PVA as a 3D evaporator caused the evaporation rate and transportation speed of water to reach a balance, and the salt was quickly dissolved at the superhydrophilic interface. This 3D salt-resistant Janus evaporator achieved an evaporation rate of 2.26 kg m-2 h−1 under 1 kW m−2 illumination.

Composition of the Gas-Air Mixture in the Containment and Suppression of Forest Fires with Promising Extinguishing Agents

This paper presents experimental research findings on the gas composition of pyrolysis and combustion products of typical forest fuels (leaves, needles, twigs, a mixture of these, and timber). These experiments were performed for the combustion and application of a fire extinguishing agent to a pyrolyzing material. Water, a bischofite solution, a bentonite slurry, and a foaming agent solution were utilized. Two gas analysis systems were used, as follows: an industrial one based on CO2, CO, H2, CH4, and O2 sensors and a scientific one (a gas analyzer with H2, CH4, H2S, SO2, CO, and CO2 sensors). Fires were extinguished by using two common techniques, as follows: continuous liquid supply and cycling spraying. The comparative efficiency of applying a group of fire extinguishing agents to forest fires was estimated, taking account of liquid consumption, suppression time, and environmental pollution. A method was proposed for calculating the relative efficiency factors of fire extinguishing agents when containing and suppressing forest fires, allowing for the consumed time, resources, and anthropogenic emissions.

Experiment Study on the Effectiveness of Various and Mixed Kinds of Low Expansion Foam of 120# Gasoline Pool Fire Suppression

Storage tank fires can endanger society and the environment by generating intense heat radiation, rapidly spreading blazes, and cataclysmic explosions. Various types of foam and even two or more mixed foams are commonly used in storage tank fire disposal sites. This research aims to experimentally and analytically assess the efficacy of various and mixed forms of foam in putting out 120# gasoline pool fires. A series of foam fire extinguishing and re-ignition tests were conducted using a laboratory fire-extinguishing device that gently released low-expansion foam. In this work, a 2.4 m-diameter steel round tray was utilized to model the full-surface fire of an oilcan in a large oil depot base. The non-dimensional (T* = TExtinguishing/Tboiling point) average temperature of 0.62–0.66 is used in this study to represent the fire extinguishing temperatures of 120# gasoline fuel. The power law is still followed during the spreading phase as the length of the foam spreads further with time. When combined, 6% aqueous film-forming foam solution and alcohol-resistant aqueous film-forming foam solution (AFFF + AFFF/AR) have the highest flow velocity of 0.0189 m s−1. According to the results, synthesis foam solution combined with alcohol-resistant fluoroprotein foam (S + FP/AR) provided the greatest cooling effect, followed by S + S/AR (alcohol-resistant synthetic foam solution), AFFF/AR, S + AFFF, S/AR + AFFF, and finally S/AR + AFFF. According to the results, foam with an expansion ratio of 8.7:1 (FP (fluoroprotein foam solution) + AFFF/AR) has greater re-ignition resistance and burn-back protection. A referable tactic for choosing foam for liquid fire suppression is shown in this paper. The results suggested that FP and AFFF should be used for effective fire suppression in this hydrocarbon fuel fire rescue. Then, we can use synthetic foam and AR foams to provide continuous cooling and prevent the fire from re-igniting through efficient foam coverage.

Enhancing protein-based foam stability by xanthan gum and alkyl glycosides for the reduction of odor emissions from polluted soils

Odorous contamination would occur in the polluted soils' remediation of the abandoned industry factory. To suppress odorous substances’ emissions, a novel foam was prepared with plant protein, xanthan gum, and alkyl glycosides. Since xanthan gum and alkyl glycosides have the characteristics of prolonged foam half-life and enhanced foaming ability, the optimal ratio of xanthan gum to alkyl glycosides is crucial during foam formulation determination. When xanthan gum concentration increased from 0.00% to 0.30%, the viscosity of the foaming solution increased from 12 to 223 mPa∙s, while the surface tension declined by 12.3%. As a result, the foam half-life increased from 0.3 to 56 h, and the foaming volume decreased by 25.5%. On contrary, with the addition of alkyl glycosides, the surface tension decreased significantly, and the foaming volume increased by 36.5% under the xanthan gum concentration of 0.30%. Therefore, the optimal content of xanthan was 0.30% in the presence of 100 mM alkyl glycoside. Then, this novel foam could prevent 67% of p-xylene from escaping within 24 h. In actual sites, novel foams showed a barrier rate of over 75% on different odorous substances most of the time.

Separation and Purification of Recombinant β-Glucosidase with Hydrophobicity and Thermally Responsive Property from Cell Lysis Solution by Foam Separation and Further Purification.

The aim of this study was to separate and purify recombinant β-glucosidase (GLEGB) with elastin-like polypeptide (ELP) and graphene-binding peptide (GB) from cell lysis solution by foam separation and further purification. The study of foam property of GLEGB cell lysis solution indicated that it had excellent foaming property and foam stability, which was suitable for foam separation. This could be due to the GB tag with hydrophobicity, which made the recombinant β-glucosidase with GB preferentially adsorb on the surface of bubbles. At optimum operating conditions of foam separation, the enzyme activity recovery of GLEGB could reach 95.63 ± 1.0%. The foam solution of GLEGB was further purified based on the thermally responsive property of the ELP tag, and the purification fold of GLEGB could reach 29.6 ± 0.5 at the optimum operating conditions. The prominent purification effect indicates that this technique is a simple and efficient technique for the separation and purification of recombinant enzymes.

A Comprehensive Review of the Role of CO2 Foam EOR in the Reduction of Carbon Footprint in the Petroleum Industry

By trapping CO2 and storing it in matured and depleted geological formations, atmospheric CO2 release can be reduced. Carbon capture and storage on a large scale can help to stabilize atmospheric greenhouse gas emissions. This can be achieved by using anthropogenic CO2 for enhanced oil recovery (EOR), which encourages advances in secure CO2 storage while enhancing the oil production process. This interaction is expected to hasten the development of CO2 storage technology and lower emissions from oil producing operations. Reducing CO2 mobility in the reservoir is crucial to achieving this goal as effectively as possible, and in situ foam generation offers a viable solution. It has been shown that implementing a blend of CO2 and foaming solution considerably reduces CO2 mobility and front propagation. Although there have been a few reviews of carbon capture, utilization, and storage (CCUS), none of these have concentrated on the role of foam EOR in achieving carbon neutrality. Therefore, in this brief review, methods for achieving carbon neutrality with foam EOR are comprehensively reviewed. In order to store CO2, the utilisation of atmospheric CO2 to generate foam is the main topic of this review. This approach can boost financial incentives for the energy sector, help to lower carbon emissions, and make it possible to produce oil from depleted reservoirs in a more sustainable way. Thus, identifying and examining the governing mechanisms that affect CO2 storage during foam flooding as well as reviewing the various techniques for estimating CO2 storage under actual reservoir circumstances are among the goals of this work.

Rigid composite bio-based polyurethane foams: From synthesis to LCA analysis

This paper provides a bio-based polyurethane foam (PUR) solution, following a cradle-to-factory approach. The design of bio-based rigid PURs, reinforced with sustainable fillers have gained remarkable attention in “green” construction sector. Their marked performances make them a viable solution for synthetic counterparts' replacement. In this work, functionalized hemp fibers and silica powders were selected as reactive fillers, imparting multifunctional properties to the designed PURs. Hemp fibers underwent ultramilling, phenolation and/or nano-transformation to obtain four different filler types, i.e. nano- and micro-sized hemp particles, and functionalized hemp nano and micro-size couples. Silica nanoparticles were extracted from rice husk and functionalized with phytic acid. The composite PURs were prepared by adding 6 % wt of filler to cardanol/vegetable-based polyol solutions. The effect of the filler's chemistry on the properties of the foams was investigated. A Life Cycle Assessment of the filler production stages was performed to assess their eco-profile impact.

Liquid foam under simple shear: Local flows in the films

Predicting the effective viscosity of a foam as a function of its bubble size, liquid fraction and chemical composition is still an open question. The confinement of the liquid phase between the bubbles is expected to strongly enhance the local deformation rates. However, these local deformations are induced by interfacial stresses, which are limited by the surface tension accessible range: above a critical bubble size and/or shear rate, it is impossible to shear the whole film separating the bubbles. In this paper, we investigate this large bubble regime by imposing a simple shear to a minimal foam made of five interconnected films. We present a new local deformation pattern, with a relaxation process lasting long after the motor stops, that we characterize for a large range of shear rate and for different foaming solutions. A direct evidence of the absence of shear during the relaxation has been obtained for one solution. At 10 s−1, this original large bubble regime should be relevant for foams with bubbles larger than 300 microns.

О корреляции кислородного индекса с результатами оценки воспламеняемости и горючести полимерных композиционных материалов, полученных маломасштабными методами

PURPOSE. Most polymer composite materials (PCMs) are highly flammable, which significantly limits their use in the construction industry. Therefore, in the Russian Federation, much attention is paid to the development of effective methods for reducing the flammability of PCM. To assess the flammability and combustibility of PCMs, various small-scale methods are being studied, based on determining the temperature, thermal, concentration and kinetic parameters of combustion and flame propagation over their surface. This significantly complicates the analysis of scientific and technical literature. Therefore, the purpose of this work is to establish correlation between small-scale methods for assessing the combustibility and flammability of PCM. The objects of study were PCM for construction purposes (fiberglass, foam and polymer solutions) based on polymers of various chemical structures. METHODS. While assessing the flammability and combustibility of PCM, both GOST methods and methods described in the scientific and technical literature were used. Findings. Correlation has been established for the values of the oxygen index (OI) with the results of assessing the flammability of polymer composites using calorimetry methods and the flammability index Кср when tested by the “ceramic pipe” method, the values of the heat of combustion and the critical density of the ignition heat flux. For gas-filled polymers, OI = 30,18⋅Кср , which makes it possible to calculate the OI value of foam plastics based on the results of determining the flammability of materials using the ceramic pipe method. It is shown that with an oxygen index value of more than 26–27%, composites belong to moderately flammable materials, and with OI &gt; 30% – for low-flammable materials. Data are presented on the influence of the chemical structure of oligoether methacrylates on the heat of combustion and oxygen index of cross-linked polyester methacrylates. It was revealed that the proportionality coefficient (A) in the equation OI/г = А/∆Hcг is different for individual homologous series of the studied polymers. At the same time, polymers of linear structure (polyethylene, polypropylene, polystyrene, polymethyl methacrylate) have lower values of coefficient A (2.68 kJ/g) compared to network polyether methacrylates (A = 2.86–3.27 kJ/g). RESEARCH APPLICATION FIELD. The established correlation of the OI values with the results of assessing the flammability and combustibility of PCM obtained by small-scale methods will make it possible to use the OI method in the development of fire-resistant PCM of a new generation. CONCLUSIONS. The established correlation between OI values and other indicators of flammability and combustibility of PCM will significantly reduce the amount of research in the development of composites for construction purposes. The results of the work can be used in various fields of science and technology.

Research on the Mixing Mechanism and Parameter Optimization of Liquid Nitrogen Foam Generator

Nitrogen foam is expected to be an effective method to extinguish large-scale fires and suppress explosions. The key to its foaming process is that gas nitrogen (N2) and a foam solution are mixed uniformly in a foam generator. Moreover, liquid nitrogen (LN2) has been proposed as a source of gas nitrogen to generate nitrogen foam in previous experimental works. In this paper, the flow and heat transfer characteristics between liquid nitrogen and the foam solution are explored by numerical methods, which are then utilized to optimize the parameters of the foam generator. It is found that the flow pattern of the foam generator with a cone spoiler is a stratified flow by establishing the mixture and Lee’s evaporation-condensation model in ANSYS Fluent. Moreover, the spoiler in the foam generator plays a crucial role in breaking LN2 into droplets and increasing the contact area between phases, and a distance of 10 mm from the inlets to the spoiler is recommended. From previous results, an unreasonable flow rate ratio of LN2 to a foam solution may lead to icing or a low volume fraction of nitrogen, thus a flow rate ratio of 1:50 is determined in the foam generator. As for the shape of the spoiler, the spiral spoiler shows the best foaming performance compared to cone and semisphere spoilers, due to its fluid rotation instead of translation, which effectively increases the N2 volume fraction of foam from 0.616 to 0.717. Therefore, the mixing characteristics of the foam generator in this work lays a foundation for devising a practical nitrogen foam generator.

Interfacial and rheological properties of long-lived foams stabilized by rice proteins complexed to transition metal ions in the presence of alkyl polyglycoside

HypothesisTransition-metal coordination complexes are hopeful to make advanced structural materials, since the metal-coordination bonds, unlike typical covalent bonds, can regenerate after rupture, allowing for dynamic, tunable, and reversible mechanical characteristics. Integration of metal-coordinate crosslinking in foam material has rarely been reported. ExperimentsWe developed the hydrolyzed rice proteins (HRP) as the building block for amphiphilic transition-metal coordination complexes that could be used to make long-lived foams with high yield stress. Surface properties of the foaming solution were determined using equilibrium and dynamic tensiometers. Structural information of aggregates in the foaming solution was detected by small-angle X-ray scattering (SAXS) and Cryo-Tem. Visualization of liquid flow in the interfacial liquid film was studied by the reflective optical interference technique. Rheological response of liquid foam was characterized by a rheometer with amplitude-sweep and frequency-sweep modes. FindingsIn the presence of transition metal ions, HRP formed a mechanically strong rigid film. In the absence of transition metal ions or the addition of alkyl polyglycoside (APG), HRP was desorbed to produce a mobile film with a detergent state. The two interfacial states could be actively switched based on facile changes in bulk solution composition (metal ions or alkyl glycoside or chelating agent), and the switching between the two states led to the formation of extremely stable foam with high yield stress or the collapse of foam with a significant decrease in yield limit. The transition-metal coordination complexes adsorbed on the surface of the liquid film could increase the elastic modulus of liquid foam by more than an order of magnitude without increasing the viscosity of the foaming solution. We further revealed the origin of foam stability/instability and used other well-characterized proteins to prepare transition-metal coordination complexes to make long-lived foams. The cases described in this work illustrate the universal nature of the strategy, which in principle can be extended to many types of protein.

Self-sustaining organic acid system for treatment of terrigenous reservoirs

A method for acid treatment of the bottom zone of a terrigenous heterogeneous reservoir, including isolation of highly permeable reservoir areas with a foam solution formed in the reservoir and subsequent treatment of low-permeability reservoir zones with an organic acid systemhas been developed. The composition of the organic acid system is selected depending on the carbonate content of the bottom well area. The efficiency of the method is increased by increasing the foam system stability, the depth and thickness coverage of the formation, and by reducing corrosion activity as a result of the use of organic acid systems. As carbonate rocks dissolve, the reservoir and filtration characteristics of the formation will increase. Keywords: acid treatment; citric acid; whey; polymer; crosslinker; foam system; stability; carbonate content; permeability.