Foam System Research Articles

Experimental Evaluation Study on High Temperature Tolerance Foam for Profile Control of Steam Huff-n-Puff

In the process of steam huff and puff to develop heavy oil reservoirs, steam channeling is the main factor that restricts the development effect, which causes that the swept area of steam is limited and unable to heat heavy oil adequately. It is important to find an economical and efficient method to prevent steam channeling from happening at steam huff and puff production; thus, a DF-2 high temperature tolerance foam system is proposed to assist steam huff and puff production in this paper. Firstly, utilizing high-temperature aging tank and high-speed stirrer device, the foam quality of DF-2 foam and four kinds of other common industrial foams were evaluated and compared; this experiment result shows that the DF-2 foam has the best temperature tolerance. Whereafter, three groups of single-sandpack experiments were carried out to investigate the change of DF-2 foam resistance factor under different conditions, which included the influence of gas liquid ratio, injection pattern, and crude oil, and the blocking capabilities of DF-2 foam were studied. Through the dual-sandpack experiment, the profile control performance and diversion capacity of the DF-2 foaming agents were studied and evaluated systematically. Finally, the DF-2 high temperature tolerance foam agent was applied to on-site production. The sandpack experiment results indicated that the resistance factor of DF-2 foam agent decreased with gas-liquid ratio, and the optimal gas-liquid ratio was 1 : 1. Coinjection of gas and liquid with foam generator is better than slug injection. Crude oil in sandpack can reduce blocking capability to some extent. During the application of the DF-2 high temperature tolerance foaming agent in the steam huff-n-puff process in M-12 Oilfield block, it had a good performance of profile control and foam blocking, solving the problem of steam channeling and improving the steam sweep area to increase the steam-oil ratio in the heavy oil reservoir, and the production performance of steam huff and puff was improved to a great extent.

The Direct Sandwich Composite Molding (D-SCM) Process: Sandwich Manufacturing and Characterization

Sandwich structures benefit from the geometrical stiffening effect due to their high cross-sectional area moment of inertia. Transferred to carbon fiber-reinforced plastic (CFRP) components, the needed amount of carbon fiber (CF) material can be reduced and with it the CO2 footprint. The combination of a light foam core with continuous fiber-reinforced face sheets is a suitable material combination for lightweight design. Traditionally, CFRP sandwich structures with a foam core are manufactured in a two-step process by combining a prefabricated foam core with fiber-reinforced face sheets. However, in addition to the reduction in the used CFRP material, manufacturing processes with a high efficiency are needed. The objective of this paper is the sandwich manufacturing and characterization by using the Direct Sandwich Composite Molding (D-SCM) process for the one-step production of CFRP sandwich structures. The D-SCM process utilizes the resulting foaming pressure during the reactive polyurethane (PUR) foam system expansion for the impregnation of the CF-reinforced face sheets. The results of this work show that the production of sandwich structures with the novel D-SCM process strategy is feasible in one single manufacturing step and achieves good impregnation qualities. The foam density and morphology significantly influence the core shear properties and thus the component behavior under a bending load.

Multi-parameter screening study on the static properties of nanoparticle-stabilized CO2 foam near the CO2 critical point

The important role of nanoparticles (NPs) on foam stabilization under harsh geological conditions has been well recognized. In this paper, the Orthogonal Experimental Design (OED) method is adopted to investigate the synergy effects of six parameters, including NP concentration, surfactant concentration, oil concentration, salinity, temperature, and pressure, under five levels in the range of 0–0.2 wt%, 0.1–0.5 wt%, 0–4 wt%, 0–8 wt%, 20–60 °C, and 5.5–9.5 MPa respectively. K values and B values obtained in the OED experiments are employed to show the single parameter effect and the importance of each influential factor on foam static properties. It is concluded that system temperature and pressure, which has the highest B values of 22 mm and 18 mm on foam height results, are the dominant parameters on foamability, whereas temperature with B values of 80% on foam decay rate is the dominant factor on foam stability. It is observed when the system condition is close to the CO2 critical point, the foamability and stability of the NP-stabilized foam are much worse than under conditions far from the critical point. At last, optimal formulation of surfactant and NP concentration is proposed and validated for two geological cases of 45 °C and 55 °C with salinity and oil presence. It is expected the experimental technique, as well as the research results, reported in this paper could help the laboratory screening and formulation optimization of the complex NP-stabilized ScCO2 foam system.

Laboratory Studies for Design of a Foam Pilot for Reducing Gas Channeling from Gas Cap in Production Well in Messoyakhskoye Field

Summary This paper highlights the difference between foam injection for gas blocking in production well and injection well and emphasizes the use of polymer enhanced foam. Moreover, this paper shows systematic experimental methods for choosing suitable foam systems for gas blocking in production well considering different factors, which provides a guide regarding what kinds of foaming agents and polymer stabilizers should be used and how to evaluate them for designing a pilot application. The target in this work is the Vostochno-Messoyakhskoye field, operated by Gazpromneft, which is currently experiencing gas channeling from the gas cap in production wells because of strong heterogeneity. Foam has long been considered as a good candidate for gas blocking. However, foam injection for gas blocking in production wells is different from that in injection wells, which requires a long-term impact on gas-saturated highly permeable areas without significantly affecting the phase permeability of oil in the reservoir. Therefore, for gas blocking in production well, a long half-life time of foam is required to sustain stable foam because a continuous shear of surfactant solution/gas cannot be achieved as in injection wells. Thus, reinforced foam by polymer (polymer-foam) is chosen. Four polyacrylamide polymer stabilizers and five anionic surfactants were evaluated using bulk test to determine foaming ability, foam stability, and effect of oil by comparing foam rate and half-life time to determine the suitable foam system with optimal concentrations of reagents. Furthermore, filtration experiments were conducted at reservoir conditions to determine the optimal injection mode by evaluating apparent viscosity, breakthrough pressure gradient, resistance factor, and residual resistance factor. Polymer can significantly improve half-life time (increase foam stability), and the higher the polymer concentration, the longer the half-life time. But simultaneously, a high polymer concentration will increase the initial viscosity of the solution, which not only decreases the foam rate but also increases difficulties in injection. Therefore, an optimal polymer concentration of about 0.15–0.2 wt% is determined considering all these influences. Filtration experiments showed that the apparent viscosity in the core first increased and then decreased with foam quality (the volumetric ratio of gas to total liquid/gas flow). The optimal injection mode is coinjection of surfactant/polymer solution and gas to in-situ generate foam at the optimal foam quality of about 0.65. Filtration experiments on the different permeability cores showed that the gas-blocking ability of polymer-foam is better in high-permeability cores, which is beneficial for blocking high-permeability zone. It should also be noted that under a certain ratio of oil-to-foam solution (about lower than 1 to 1), the presence of high-viscosity crude oil slowly decreased the foam rate with increasing oil volume, but significantly increased the half-life time (i.e., foam stability which is favorable for foam treatment in production well).

Self-foamed biosystem for deep reservoir conformance control

The goal of this research is to develop formulations for blocking highly permeable zones using cheap, traditional reagents and materials, and to determine the dependence of the position of the blocking screen on the degree of watering of the oil formation in order to maximize the efficiency of oil displacement. Using readily available chemical reagents and biosystems, technology for generating a stable foam system with adjustable rheological properties and providing deep alignment of the displacement front has been developed. In the study, the required penetration depth of the proposed foam system to achieve the maximum effect at different water cuttings was determined; moreover, the effect of pressure on the stability of the foam system generated as a result of decomposition of the biosystem was studied, and the significant effect of gas saturation on the rheology of the foam system was confirmed. It was further established that with a high water-cut (more than 90%), isolation was most effective in the production wells. At a 50% water cut, the deep diversion of the injected fluid gave promising results, however, the best results were achieved using isolation near the discharge line immediately after the water breakthrough in the production wells.

PH-Dependent Binding Behavior of the α-Lactalbumin/Glycyrrhizic Acid Complex in Relation to Their Foaming Characteristics in Bulk.

This work aimed to understand the relationships of the interaction mechanism and foaming characteristics of α-lactalbumin (α-La) and glycyrrhizic acid (GA) after acidic (pH 2.5) and neutral (pH 7.0) treatment. The critical aggregation concentration (CAC) of GA in the presence of α-La was 0.6 mM at pH 7.0, while it was 1.0 mM at pH 2.5. Also, in the presence of a GA concentration of 0-15.00 mM, more GA molecules combined onto the α-La surface at pH 2.5 than at pH 7.0, as evident from the binding isotherms. The turbidity and particle size of α-La/GA were greater in acidic solution than those under neutral conditions. This result could be interpreted by the formation of aggregates under higher GA concentration at pH 2.5. Meanwhile, the viscosity of the complex was higher at pH 2.5 than at pH 7.0 in the presence of 3.00-15.00 mM GA, as analyzed from the rheological properties. The foaming ability (FA) of α-La was significantly enhanced in the presence of 10.00 mM GA. Simultaneously, acidic solution could generate a more stable foaming system with a thicker film layer stabilized by the complex compared with neutral solution. These findings could be beneficial for developing a kind of acidic food-grade foaming agent.

Experimental Evaluation of a Polymer Foam Agent on the Foam Stability, Concern to Surfactant, Nanoparticle, and Salinity

Summary In recent years, rising oil demand has led to a strong need to improve enhanced oil recovery (EOR) techniques. One of the most common methods for EOR in the oil industry is gas injection. When gas is injected into the reservoir, because of the low density of the gas relative to the oil and the undesirable gas mobility ratio, problems such as gas uptakes and the injected gas flow channeling arise, thus reducing the efficiency of oil production. Foam can improve mobility and increase EOR by reducing gas permeability. One of the most important properties of the foam is stability which affects the EOR. In recent years, many studies have been conducted on the use of nanoparticles (NPs) and polymers as stabilizers, but the use of stabilizers that have the ability to produce foam has been less studied. The main objective of this work is an experimental study of foam stability by the dynamic method of CO2 gas injection and static method of “Ross-Miles” in the presence of sodium dodecyl sulfate (SDS) and nanosilica in combination with a foaming polymer such as hydroxyethyl cellulose (HEC). The aim of this study was to compare the effect of a polymer that has the ability to produce foam relative to the stabilizer of NP on the foam stability. The zeta potential and the structure of the foam bubbles were measured to better understand the parameters affecting the foam stability. Experimental outcomes of this work show that the HEC polymer, despite being a foaming agent, has less effect on the foam stability than the nanosilica. That is, under similar conditions, SDS-NP based foams are more stable than SDS-HEC based foams. In addition, the composition of the SDS-NP-HEC foam system shows weaker foam performance compared to the case of SDS-NP and SDS-HEC dispersions. Also, salinity has an optimal concentration in which foam concentration has the best performance and stability; in this study, the optimal NaCl salt concentration is 2 wt% NaCl.

Experimental Study on Application Performance of Foamed Concrete Prepared Based on a New Composite Foaming Agent

The performance of foaming agent plays a key role in the forming quality of foamed concrete. In order to overcome the limitation of single composition of traditional foaming agent, this paper adopts the research method of multicomponent composite combined with the foaming theory and preparation technology of foaming agent, a new protein composite foaming agent was prepared using a mixture of anionic surfactant (SCA), nonionic surfactant (APG), and foam stabilizer (AR), and then, the effects of different surfactant mass ratios and foam stabilizer concentrations on the properties of composite foaming agent were studied by a series of tests. The results show that the optimal mass ratio of surfactants is mAPG: mSCA = 2 : 1, and the optimal concentration of foam stabilizer is 0.5 g/L, which verified that the self-made composite foaming agent system in this paper has the advantages of strong foaming ability, excellent foam stability, and low cost. In addition, foamed concrete was prepared on the basis of the optimized composite foaming agent system, and the influence rules of different foaming agent solution volumes, water-cement ratios, and diatomite dosages on the performance of foamed concrete were revealed through laboratory tests and SEM images. At the same time, the optimal ratio of each component required for the preparation of high-quality foamed concrete was further obtained by using the response surface analysis of compressive strength. The research results provide an important reference for the preparation of high-performance foamed concrete and corresponding foaming agent, which is beneficial for solving the disadvantages of poor foam stability in the existing foaming agents and improving the application level of foamed concrete in engineering construction.

Impact of Amphiphilic Nanostructures on Formation and Rheology of Interfacial Layers and on Foam Film Drainage

The aim of the present studies is to clarify how the surfactant adsorption layer properties are related to the course of the drainage parameters of microscopic foam films in the special case of aqueous solutions containing premicellar amphiphilic nanostructures. The scope of the research covers the adsorption dynamics, construction of equilibrium adsorption isotherms, surface rheology of interfacial layers, and foam film drainage kinetics. It is established that, in the premicellar domain, there are concentration intervals, where the considerable irregularities of adsorption layerproperties are observed: several plateau regions in the surface tension isotherms, unusual changes of the surface rheological characteristics, etc. The systematic investigation of the drainage of foam films obtained from these solutions show that the dependences of basic kinetic parameters of the films on the amphiphile concentration run in synchrony with changes in the adsorption layer properties. Thus, the presence of smaller loose aggregates (premicelles) plays a significant role for the kinetic stability of films. The importance of this research is related toproviding a better insight into the initial stages of self-assembling phenomena and into the factors determining thedrainage and the stability of thin liquid films. The results have implications for the understanding and the correct prediction of properties of foam systems.

Influence mechanisms of several parameters on the interaction between flowing wet foam and settling particle

In practical application, many factors can influence aqueous foam structure. Due to the structural variability of bubble film in a flowing foam system containing a settling particle, the microscopic influence mechanisms of some parameters of both the foam and the particle on the interphase forces are still unclear. In this work, without considering ingredients of the foam fluid, a series of quasi-static multiphase models is built, and the interaction force between the flowing wet foam and the settling particle is firstly investigated at the bubble scale. Then we mainly focus on the parameters, including the foam quality (i.e., gas fraction of a foam), the contact angle between gas-liquid-gas and gas-liquid interfaces and the particle size, and analyze influences of these parameters on the statistical averages of the interphase forces. It shows that both the drag and the lift forces rise with the increase of each of these parameters. More importantly, the foam film and the bubble pressure components of these forces are in detail discussed based on the special structural evolution behaviors of the foam with these different parameters. This study, at the bubble scale, reveals the potential influence mechanisms of these parameters on the interaction between the settling particle and the flowing wet foam.

Rapid Carbon Dioxide Foaming of 3D Printed Thermoplastic Polyurethane Elastomers

Polymeric foam preparation using the carbon dioxide (CO2) foaming technique is fascinating. Until now, the CO2-based foaming process has been carried out for a long saturation time. Once it is possible to produce a polymeric foam in a low saturation time, it can enhance foam production. This study investigates the foaming behavior of 3D printed TPU samples with three different hardness values. The variation of infill density in 3D printed samples provides a macroporous range in the sample and creates a path for the gas molecules to reach the polymer. Such a gas flow path expands the foam processing technique to be carried out at low saturation time and pressure. The foaming process carried out here follows two steps: first, CO2 gas saturation in a high-pressure stainless-steel vessel; second, then hierarchical microporous generation by devising a thermodynamically unstable condition by placing the gas saturated sample in a hot water bath set up. The results showed that the increase in saturation time and pressure increases the expansion behavior of the foam samples, whereas an increase in infill density restricts the foam expansion behavior. The crystalline hard segment (HS) enhances the heterogeneous cell nucleation and reduces the shrinkage of the foam samples. The foam sample with low infill density showed low compression strength. It could be improved by filling the macroporous gap with hydrogel during printing. This hydrogel-packed low infill density foam showed an increased compression strength of 0.8 MPa at 80% strain than the neat foam sample (without hydrogel) 0.12 MPa at 80% strain, confirmed through the cyclic compression test. Hence, this 3D printing integrated subcritical solid-state foaming system offers unparalleled freedom to design and create foam and increase its production. The one-pot preparation of low-density higher compression strength foam using hydrogel makes this technique more feasible for high-end applications.

The study of ultralow interfacial tension SiO2-surfactant foam for enhanced oil recovery

Surfactant selection and formulation are key factors in technological and economic success in chemically enhanced oil recovery (cEOR) applications. In this study, the silica nanoparticle (SNP) was added in an ultralow interfacial tension foam (ULIFT), called SNP-ULIFT foam, which was successfully prepared by ternary surfactant systems. The Carboxylate-based extended surfactant (Carboxylate), Dioctyl Sulfosuccinate Sodium salt (AOT), and Sodium Diphenyl Oxide Disulfonate (DODS) at a 0.48:0.48:0.04 wt ratio were conducted as the surfactant system. Remarkable results in the selected surfactant system were observed in terms of the ability to form foaming and ultralow interfacial tension (IFT) at 60 ± 2 °C with the ADNOC crude oil (Abu Dhabi National Oil Company) as model oil. The optimum salinity of the surfactant system was found at 2.5 wt% (8:2 Na:Ca by weight), indicating a minimum IFT of 0.0019 mN/m. The adsorption capacities at the optimum salinity condition of each surfactant in the mixture onto the SNP's surface were 1.4, 7.3 and 19.4 molecule/nm2 for the DODS, Carboxylate and AOT surfactants, respectively; the calculated total surfactant adsorption was 2.6 mg surfactant/mg nanoparticles. While in the presence of SNP, the surfactant adsorption of the ternary surfactant foam system onto the sand surface was significantly reduced by 16.2% at 200 psi and 60 °C when compared with the neat ULIFT foam system. It was remarkably noted that the adsorption of the surfactant onto the SNP surface could result in a reduction of surfactant adsorption onto the sand surface. The oil recovery performance in the core flood by ULIFT foam was the greatest with 43% of Original Oil in Place (OOIP), and it further increased by 13% in the presence of 200 ppm SNP. In addition, the stress and viscosity of ULIFT microemulsion significantly decreased with SNP. This suspension exhibited the most non-Newtonian behavior with shear-thinning behavior over different ranges of shear rate. Therefore, SNP-ULIFT foam with the appropriate surfactant selection was a successful method for improving oil recovery performance.

Enhanced oil recovery by foam flooding using foam stabilized with modified Fe3O4 nanoparticles

Nanoparticles (NPs) could enhance the stability of foam to allow recovery of greater amounts of residual oil during foam flooding. However, conventional nanoparticles are non-recyclable and affect the quality of the produced oil. Magnetic nanoparticles could respond to magnetic field and be recycled for reuse, thus reducing the cost for enhanced oil recovery (EOR) process and improving the quality of the produced oil. In this study, Fe 3 O 4 nanoparticles were used as foam stabilizer. The Fe 3 O 4 nanoparticles were modified with tetraethyl orthosilicate (TEOS) and n -dodecyltrimethoxysilane (WD-10) to make them hydrophobic. The optimal nanoparticles were Fe 3 O 4 @SiO 2 -700 with a contact angle of 68.5°. Foam was generated by sodium dodecyl sulphate (SDS) surfactant and the longest drainage half-life time was 746 s in the 1 wt% NPs+0.23 wt% SDS+3 wt% NaCl foam system. After evaluating foam stability, the nanoparticles were recycled and reused to stabilize foam again, and the results indicated that recycling nanoparticles three times was optimal. Finally, the core flooding experiments showed that the nanoparticles stabilized foam EOR rate was 17.4% and the system obtained a greater pressure drop to improved sweep area. These results indicated that the magnetic nanoparticles could stabilize foam effectively and could be recycled by magnetic field to reuse in stabilizing foam. This study suggested directions for further studies concerned with the application of magnetic nanoparticles for enhanced oil recovery. • Modified Fe 3 O 4 nanoparticles possessed the recyclability in stabilizing foam. • The Fe 3 O 4 nanoparticles coated by TEOS can improve the ability to stabilize foam. • The optimum contact angle of Fe 3 O 4 @SiO 2 was 68.5° in this work. • The recycled nanoparticles can still stabilize foam after core flooding experiment.

Facile Method for Preparing Hierarchical Al2O3-Glass Foam Ceramics with Superior Thermal Insulating Property.

Porous ceramics are good candidates for thermal-insulating materials. Glass is a low-cost material that possesses low intrinsic thermal conductivity of less than 10 W·m-1·K-1. However, the mechanical strength of a homogeneous glass material is fairly low. We, in this work, have fabricated Al2O3-hollow glass sphere (HGS) foam ceramics with a facile particle-stabilized foaming method. The obtained foam ceramic presents a hierarchical microstructure that is rare to be seen elsewhere using this foaming technique. The foaming system contains two types of particles having opposite charges, and the particle-stabilized foaming mechanism is hence discussed. The optimal sample possesses a porosity above 94% with a thermal conductivity as low as 0.0244 W/m·K, which reaches the level of superinsulating materials. The compressive strengths of the foam ceramics range from 0.07 to 0.83 MPa. The effective medium theory model is used to calculate the thermal conductivities as reference. The deviation of the theoretical values from the experimental ones are derived from the effect of the hierarchical microstructure of the foams. The results of this work may deepen one's understanding and pave new ways for the particle-stabilized foaming technique. The unique microstructure of the ceramic may also shed some light on fabricating superior thermal-insulating ceramic materials.

Stable foam systems for improving oil recovery under high-temperature and high-salt reservoir conditions

Foams have high apparent viscosity when flowing in porous media, therefore foam flooding could significantly improve unfavorable mobility ratios, increase sweep efficiency, and enhance oil recovery. However, the applications of foam flooding in high-temperature and high-salt reservoirs are seriously restricted as foam systems often have inferior foamability and stability in these reservoirs. In this study, to improve foam flooding effectiveness in high-temperature and high-salt reservoirs, novel foam systems with excellent stability and plugging capacity are developed by combining surfactants, additives, and polymers. The performance of bulk foam, physical properties of the solutions, and properties of foam systems in core-flow experiments are investigated to determine the synergistic effects among the components of the foam systems and their foamability and plugging effect in cores. In foam systems with sodium alcohol ether sulfate (AES) and dodecylhydroxypropyl sulfobetaine (DHSB) as surfactants, and dodecanol as additive, the combination of the components makes surface tension decreased and surface dilatational modulus increased, therefore the foamability and stability of the systems are improved. The results of core-flow experiments under high-temperature and high-salt conditions show that these combined systems require low injection rate for foam generation in reservoirs, which is beneficial for foam regeneration in reservoirs. Moreover, to further improve the foam performance, a hydrophobically associating water-soluble polymer (HAWP) is employed. The interactions between HAWP and the surfactants reduce the critical association concentration of HAWP, and result in the increase of solution apparent viscosity and foam stability. The results of core-flow experiments under high-temperature and high-salt conditions show that polymer-enhanced foam systems could significantly increase the sealing pressure, widen the sealing permeability range, and deal with the gas-channeling problem of foam flooding. These foam systems could provide a potential technical pathway for improving the effectiveness of foam flooding in high-temperature and high-salt reservoirs.

An experimental study on the structure and surface distribution of hydrophobic nanoparticles stabilized liquid foam

Nanoparticles (NPs) have been used to enhance the performance of foam in foam flooding process, and their foaming properties have been extensively studied in recent years. The primary aim of this study was to reveal the structure of hydrophobic NPs stabilized foam system, and to understand the distribution of NPs on the liquid film's surface. To achieve this objective, cryo-transmission electron microscope (Cryo-TEM), field emission scanning electron microscope (FESEM) and optical microscope were used to accomplish the observation of both the entire foam system and one single bubble. Meanwhile, the distribution of NPs on the liquid film's surface was analyzed based on the observation results and existence theories. Secondly, the impact of the NPs' concentration on the foam ‘s properties (foaming capacity and foam stability) and the bubbles' sizes were investigated. Besides, the observation results revealed the two-dimensional structure and particle distribution of the NP stabilized foam, and a relationship between the structure and the performance was established based on the investigation on foam's properties. Based on the experimental results, the NPs and surfactants were conjectured to be located at intervals on the surface of the liquid film, meanwhile, the NPs shown significant positive effect on the foam's stability but weak impact on the foaming capacity. • The structure of the foam was observed by a Cryo-TEM. • The surfactants and nanoparticles were arranged at intervals on the surface of the liquid film. • Hydrophobic nanoparticle can improve the stability of foam with minor impact on the interfacial tension.

Study on Hydrate Formation and Absorption Effect in Lng-High Expansion Foam System

Study on Hydrate Formation and Absorption Effect in Lng-High Expansion Foam System

Эффективность комбинации огнезащитных вспучивающихся покрытий для стальных конструкций

Introduction. Steel constructions are one of the most widely used and rational types of constructions for buildings and structures of various functional purposes. As advantages in comparison with constructions made of other materials, their high load-bearing capacity, industriality, ease of installation are noted. One of the disadvantages is low fire resistance. A common way to increase the fire resistance of metal structures is considered to be the use of fire protection products, the experience of which has been developed for many decades. However, as practice and the results of fire tests show, it is quite difficult to obtain a stable and reliable result using such fire-retardant systems. Goals and objectives. Analysis of work on the creation of effective flame retardant technologies. Development of formulations of thin-layer bulging coatings, taking into account their use as protective layers of combined flame retardant systems. Evaluation of the characteristics of the resulting foam layers of the developed coatings. Conducting a comparative analysis of the effectiveness of combined technologies of intumescent fire protection. Methods. The research was based on experiments conducted in a firing furnace, with the possibility of isothermal or dynamic radiation heating of the surface of a steel sample up to 1000 °С. The installation makes it possible to study the properties and structure of the expanded layer of flame-retardant coatings and their thermal insulation ability under unilateral thermal exposure. Thermoelectric converters were used to measure the temperature on the unheated surface of the sample. Results and discussion. The conducted analysis of the works testifies to numerous studies in this direction. The development of intumescent systems is of great interest. In the course of the research, the authors have developed various formulations of thin-layer flame retardant coatings, as well as their combinations based on innovative chemical technologies for steel constructions, taking into account the availability and manufacturability of the raw materials used. The results of studies on the evaluation of the thermal insulation ability of the developed foam systems have shown that the fire-retardant effect due to the combination of various swelling coatings can be increased by 30 % or more. Conclusion. A new scientific direction has been formed related to the creation of combinations of bulging flame-retardant coatings for various construction structures. The establishment of various options for the combination of the use of fire-resistant coatings opens up wide opportunities for the creation of effective protection of various building materials and structures from the effects of fire. Keywords: combined fire protection, intumescent coatings, swelling, foam, thermal insulation ability, steel constructions.

Chair Development on the Basis of Body Pressure Distribution—A Research Effort*

Abstract Surveys and studies show that more and more employees perform high- or low-skilled white-collar work predominantly in sitting postures. Therefore, comfortable sitting plays an important role in reducing the risk of musculoskeletal disorders and other harmful effects. Research efforts focus on reducing these risks by designing ergonomic chairs with multiple adjustment possibilities, allowing the chair to fit to the user's body shape or assuring a dynamic seating where the user's lower body is in continuous movement. This article summarizes the results of a research effort that evaluated the effect of several factors on sitting comfort based on body pressure distribution. The effects of foam elasticity, foam layer arrangement order, and seat support elasticity were investigated as well as the chair seat type (kneeling chair, saddle chair). Results were used to determine the optimal chair cushion including the layered foam system and seat support type. On the basis of our findings a new ergonomic chair was developed combining the advantages of static and dynamic sitting.

Deep diversion strategy of the displacement front during oil reservoirs watering

The goal of this research is to develop formulations for blocking highly permeable zones using cheap, traditional reagents and materials, and to determine the dependence of the position of the blocking screen on the degree of watering of the oil formation in order to maximize the efficiency of oil displacement. Using readily available chemical reagents and biosystems, technology for generating a stable foam system with adjustable rheological properties and providing deep alignment of the displacement front has been developed. In the study, the required penetration depth of the proposed foam system to achieve the maximum effect at different water cuttings was determined; moreover, the effect of pressure on the stability of the foam system generated as a result of decomposition of the biosystem was studied, and the significant effect of gas saturation on the rheology of the foam system was confirmed. It was further established that with a high water-cut (more than 90%), isolation was most effective in the production wells. At a 50% water cut, the deep diversion of the injected fluid gave promising results, however, the best results were achieved using isolation near the discharge line immediately after the water breakthrough in the production wells. Keywords: foam system; gas generation; stability; multiplicity; dspersion; rheology; reservoir model; displacement ratio; water cut; penetration depth.