Three-phase Foam Research Articles

Research-scale three-phase jet foam generator design and foaming condition optimization based on Box–Behnken design

Three-phase foam, namely surfactant-particle stabilized foam is a promising material in pool fire extinguishment. However, its effectiveness has not been validated. In this study, a research-scale three-phase jet foam generator, which allowed adjustments of foam slurry composition, nozzle type, air flow rate and screen aperture, was developed. In order to optimize the foaming condition, a three-factor three-level Box–Behnken design (BBD) was adopted. Fly ash (FA) particles were used as the solid phase to generate three-phase foams. As a result, the FA supported foam exhibited better stability over conventional fire-fighting foam, especially when the particle concentration exceeded a threshold value. In addition, the BBD results presented a good agreement between experimental data and fitted models. The optimal foaming condition was determined by numerical optimization. Small-scale fire extinguishing experiments were carried out and three-phase foam manifested better burnback performance compared to conventional fire-fighting foam. The design in this work can be used to study the firefighting efficiency of different three-phase foams and serve as a prototype to develop better generators for both lab research and practical application.

Stabilization mechanism of fly ash three-phase foam and its sealing capacity on fractured reservoirs

Water and gas channelling are important limiting factors for the development of fractured reservoirs. A three-phase foam system stabilized by fly ash is optimized as a sealing system to plug fractured reservoirs. The analysis covers the interfacial properties, particle adsorption effect and rheological properties to reveal the stabilization mechanism of fly ash on the three-phase foam. A sealing experiment was performed to evaluate the sealing capacity of the optimized foam system on fractured reservoirs using a natural core with artificial fracture. Results showed the optimized foam system, which consists of 0.5 wt% AOS + 4 wt% suspending agent + 8 wt% fly ash, has excellent stability with a foam half-life of more than 7 days. The adsorption of fly ash particles on the surface of the liquid film can reduce surface tension and improve viscoelasticity of the bubble films, prevent drainage of the liquid layer effectively and delay the aggregation and rupture speed of foam. The optimized fly ash three-phase foam can plug the channelling path of fractures in reservoirs efficiently with a sealing effect 20 times more than that of the conventional foam without particles. Hence, the optimized fly ash three-phase foam is an effective sealing system for plugging fractured reservoirs.

The study of the stability of aqueous three-phase fire-resistant foam in typical liquidus hydrocarbons

The utilization of solid particles in aqueous foam has a great potential in improving fire fighting efficiency. In this study, aqueous foam supported by micro fly-ash (FA) was prepared and its stability in a specific type of oil was characterized. Firstly, different amount of FA was added to study the influence of FA concentration on foamability. It showed that within a specific extent, foam expansion ratio increased with the increasing of FA concentration. And compared with conventional foams, oil resistance of FA stabilized foams, which was investigated by analyzing drainage rate and evolution process with a self-made apparatus, was remarkably improved when FA concentration exceed 4.8wt.%. Secondly, SiO2 and Al2O3 particles with different median sizes were used to study the effect of particle size on stability. However, the smaller hydrophilic particles didn’t behave better as expected. Moreover, the foam stability in three hydrocarbons was evaluated in the same way. The results indicated that the short chain hydrocarbons had much stronger detrimental effect to both two-phase foam and three-phase foam. But overall, the three-phase foam stabilized by FA exhibited much better oil resistance, so it can be used as a promising material for pool fire extinguishing and prevention.GRAPHICAL ABSTRACT

Treatment of smouldering coal refuse piles: an application in China

ABSTRACT Coal refuse pile fires are a serious health, safety, and environment hazard. The fires in Guoshan Coal Refuse Pile affect daily life of the local residents. Although conventional fire control methods (water injection, grouting and surface sealing) were used to control the fires, they rekindled soon after the fire-fighting engineering was quitted. Thus, effective methods need to be applied to extinguish the fires completely without reignition. In this paper, the environmental impact of the fire on the local land, water and air is illustrated by sample analysis and photos. The self-potential method, which achieves remote detection from the ground surface, is adopted to delineate the scope of the fires to give support for the efficient and economical extinguishment of them. The three-phase foam containing water, gas and loess is proposed to control and extinguish the fires. The corresponding fire-fighting system is also invented to fit the field work and put out the fires more efficiently and conveniently. The temperature monitoring result shows that the fires are extinguished successfully with no sign of reignition.

Characteristics and functional mechanisms of clay-cement stabilized three-phase nitrogen foam for heavy oil reservoir

The large-scale application of two-phase foam flooding in heavy oil reservoirs was restricted due to the instability of foam itself. However, the developed clay-cement three-phase nitrogen foam can make up for the short broad effectively, which benefits from very good thermal stability, salt resistance, oil sensitivity and excellent plugging performance. In this paper, 8.0 wt% clay, 0.50 wt% cement particles and 1.0 wt% foaming agent were used to generate clay-cement nitrogen foam. The synergistic effects of clay/cement reaction products, particle adsorption layer and steric network contribute to a desirable protective sheath covered compact three-phase foam system with high stability and strength, the half-life of which was 42.0 min at 95 °C. Moreover, it became more stable when formation sands exist. Generally, clay-cement three-phase nitrogen foam has three kinds of plugging form owing to different formation permeability. In less permeable formations, most foam would separate into two parts, with particles stacking at the entry end and two-phase foam moving forward. While in formations with higher permeability, all foam would flow out directly without effective plugging. Only when it comes to the formations with proper permeability can this foam achieve impressive plugging strength under the effects of Jamin and particle plugging. In addition, the foaming formula can be modified by adjusting particle-surfactant concentrations to fit various formations. Therefore, it is a promising and widely applicable water shutoff agent for heavy oil reservoirs.

A Study of the Stability Mechanism of the Dispersed Particle Gel Three-Phase Foam Using the Interfacial Dilational Rheology Method.

The dispersed particle gel (DPG) three-phase foam is a novel profile control and flooding system. The stability mechanism of the DPG three-phase foam was studied using an interfacial dilational rheology method. The results show that the elastic modulus of the DPG three-phase foam is up to 14 mN/m, which is much higher than the traditional foam. The increase in interface elasticity produces significantly positive effects on foam stability. Emphasis is given to the influences of frequency, temperature, pressure, and concentration on the viscoelasticity and interfacial adsorption of DPG particles, which change the modules of the foam interface and have a significant effect on foam stability. In addition, the microstructure of the DPG three-phase foam was observed. A viscoelastic shell is formed by the aggregation of the DPG particles on the interface. The irreversible adsorption gives the interface high elasticity and mechanical strength. The electrostatic repulsion between particles increases the spacing between bubbles. The combined effects of these factors give the interface higher mechanical strength, slow down the film drainage, effectively prevent gas permeation, and significantly improve the foam stability.

CFD Simulation of Pipeline Transport Properties of Mine Tailings Three-Phase Foam Slurry Backfill

A three-dimensional backfill pipeline transport model is developed using the computational fluid dynamics (CFD) technique, which is applied to study the pipeline transport properties of three-phase foam slurry backfill (TFSB). Based on rheological property tests and CFD simulations, the foam phase, pressure, and velocity in the pipeline system are investigated using the CFD mixture method for different bubble volume fractions and bubble diameters. The simulation results indicate that TFSB can maintain a steady state during pipeline transport, experience a markedly reduced pipeline transport resistance, and exhibit better liquidity than conventional cement slurry. Furthermore, as the bubble volume fraction increases, the resistance of the pipeline decreases and the fluidity improves. By contrast, the bubble diameter has little effect on the transport properties of TFSB. The combined results of CFD simulations, slump tests, and strength tests indicate that, when the bubble volume fraction is 15–20 vol %, TFSB can satisfy the necessary strength requirements and exhibit self-flowing transport. The CFD technique provides an intuitive and accurate basis for pipeline transport research and has the potential for wider application in studies of mine backfill.

A novel strengthened dispersed particle gel for enhanced oil recovery application

A novel strengthened dispersed particle gel (SDPG) was proposed and investigated to improve high-temperature and high-salinity stability of foam, which uses silica nanoparticles as reinforcing material to support the inner framework of particle gel. In this paper, SDPG was successfully prepared and applied to a new three-phase foam system (STPFS). Indoor experiments were conducted to evaluate the salt tolerance, thermal tolerance, plugging capacity and enhanced oil recovery capacity of the STPFS. It proved that silica nanoparticles could improve the high-temperature and high-salinity stability of the gel particles effectively. Consequently, the new three-phase foam system (STPFS) exhibited superior salt and temperature resistance, with a salinity of 80,000mg/L of Na+, 15,000mg/L of Ca2+ and Mg2+ and temperature tolerance of 110°C. In addition, core-flooding test indicated the STPFS possessed better plugging capacity with a resistance factor of 310 and better enhanced oil recovery capacity with the oil recovery increment of 26.79% under high temperature (110°C) and high salt environment (212,633.8mg/L).

Stability mechanism of a novel three-Phase foam by adding dispersed particle gel

A novel three-phase foam as a profile control agent in mature oilfields was successfully prepared by adding dispersed particle gel (DPG). The effects of surfactant concentration, DPG particle concentration, salinity, oil concentration, and the gas-liquid ratio on the foaming capacity of the three-phase foam were systematically investigated. Both the viscosity and surface tension of the surfactant solution were increased when DPG particles were added. Although adding DPG particles caused a slightly negative effect on the solution’s surface tension, the increase in solution viscosity brings significantly positive on foam stability. The DPG particles and surfactant bring a synergistic electrostatic repulsion between the three-phase foam interfaces, which prevented the coalescence of bubbles. By increasing solution viscosity, adsorption at the gas-liquid interface, non-adsorption behavior, and electrostatic repulsion in the solution, the DPG particles effectively stabilized the three-phase foam. An increase in surfactant concentration, DPG particle concentration, and the gas-liquid ratio increased foam volume and decay half-life of the novel three-phase foam, whereas an increase in salinity and oil concentration decreased foam volume and decay half-life. All the above factors affect the surface tension and viscosity of the foaming solution, and thus the abilities to reduce surface tension and increase solution viscosity are the decisive factors for the stability of the novel three-phase foam.

Flow characteristics of three-phase foam in mine gob and its application

To study the flow characteristics of three-phase foam in gob area, different perfusion experiments in coal mine gob were designed and put forward in the paper. Through the observation of flow range, flow characteristics of three phase foam were analyzed with different flow rates. And, unsteady seepage process of three-phase foam was simulated with CFD software. Base on experiment and numerical simulation results, flow characteristics of three-phase foam and its major influence factors are discussed, and the optimal arrangement distribution of mine fire control drills is also determined. Research results show that the flow range and stacking height of three-phase foam in gob are significantly influenced by gravity. The vertical stacking height and horizontal diffusion distance of three-phase foam are also directly related to the flow volume of foam perfusion, the larger flow single hole perfusion volume, the higher stacking height and the longer diffusion distance could be obtained.

Controlling coal fires using the three-phase foam and water mist techniques in the Anjialing Open Pit Mine, China

Coal fires are a serious environment, health, and safety hazard throughout the world. They damage the environment, threaten the health of people living nearby, burn away non-renewable coal, and result in significant economic losses. In this paper, the characteristics of the ignition and propagation of coal fires are illustrated first. Semi-enclosed environments (loose zones and abandoned roadways) favor the ignition of coal fires. The “upper fire” is pointed out to be prevalent and difficult to be controlled. Furthermore, the advantages and disadvantages of several commonly used techniques for controlling coal fires are analyzed. The three-phase foam and water mist techniques are believed to be effective in controlling coal fires, especially the “upper fires” in loose zones and abandoned roadways, respectively. Then, the three-phase foam coal fire extinguishing system is improved, and the water mist coal fire extinguishing system is developed. Finally, these two techniques are applied to control coal fires in the Anjialing Open Pit Mine. The results show that the three-phase foam and water mist techniques control coal fires efficiently and ensure the safe production of the mine as well as the security of personnel and equipments. Most importantly, this study provides a valuable method for the control of other coal fires.

Aqueous three-phase foam supported by fly ash for coal spontaneous combustion prevention and control

This work deals with the preparation and characterization of fly ash (FA) supported aqueous three-phase foams containing N2 for coal spontaneous combustion prevention and control. Uniform and dense three-phase foams featuring FA contents between 20wt.% and 33wt.% are prepared in batch mode using a home-made foam generating column with an internal Venturi tube. The effect of FA on the foamability, static and dynamic stability of the three-phase foams is discussed. Compared with two phase foams, the FA supported three-phase foams manifest higher static and dynamic stability, which increases with the FA content. Base on the excellent static and dynamic stability, a structure model to attach FA particles at the N2–water interfaces of the three-phase foams was proposed to elucidate the observed behaviors. The as prepared FA supported three-phase foams, exhibiting excellent coal fire extinguishing characteristic, can be used as a promising fire extinguishing material, especially for preventing the large coal area spontaneous combustion or extinguishing fire in high and unknown locations in goaf.

Fire Resistance of Three-Phase Foam with Modified Hollow Glass Microspheres

Fire Resistance of Three-Phase Foam with Modified Hollow Glass Microspheres

Experimental Investigation of Three-Phase Foam Sealing Material for Fractured Borehole

To develop a kind of ideal sealing material, uniform experiments were conducted in a simulation test device after the determination of material composition and approximate ratio range. The experimental data was fitted by stepwise regression analysis and optimal mixture ratio was obtained. The reliability is perfect when the ratio of foaming agent FP, foam stabilizer WP, solid filler RX and solid filler GX is 1.5:2:3:3. Field application tests show that sealing material in the above ratio has advantages of less time waste, higher reliability and better adaptability. It has a wide application prospect for fractured borehole sealing.

Preparation and Inhibition Characteristic of Multi-Phase Foamed Gel for Preventing <i>Spontaneous</i> Combustion of Coal

In order to prevent the spontaneous combustion of coal efficaciously, a kind of new compound material of multi-phase foamed gel, which is based on three-phase foam, composed of foaming agent, thickener, fly ash and nitrogen and formed by physical and mechanical stirring, is proposed. It makes use of the all-around capability of gel and three-phase foam to prevent mine fire. The effects of the mass fraction of foaming agent and slurry, the quantitative ratio of polymers and concentration on foam properties had been carried out. The results show that the properties of multi-phase foamed gel are the best when the mass fraction of foaming agent, polymers and slurry were 4‰, 6‰(the quantitative ratio was 1:1) and 16.66%(water cement ratio was 5:1). In addition, the inhibition characteristic of multi-phase foamed gel was studied experimentally and theoretically.

Experimental Research of Three-Phase Foam Fire-Fighting Technology in 7312-2 Caving Face Prevention Goal of a Coal Mine

Spontaneous combustion of coal is a serious threat to the normal working of the mine and the safety of miners, the research to prevent spontaneous combustion of coal has a great significance. Technology based on the three-phase bubble theory, combined with characteristics of coal of 7312-2 caving face of a coal mine in Xuzhou, using laboratory studies to determination the fly ash , Wong and a variety of surfactant , then determining the formula of three-phase foam which is fit for a coal mine coal, it can restrain goal spontaneous combustion effectively and beneficial to safety production and environmental prevention.

Prevention and control of coalfield fire technology: A case study in the Antaibao Open Pit Mine goaf burning area, China

It is very difficult to clearly detect the location of a burning area in a coal mine since it is hidden underground. So we conducted research on the distribution of the burning area before controlling it. Firstly, the original drilling technique was used to analyze and determine the loose and scope of caving of burning area through field test, and then obtained the gases and the temperature data in this area were according to the borehole data. By analyzing these data, we found out that the location of burning area concentrated in the loose and caving area; and finally, the location and development of the burning area within the tested area were accurately determined. Based on this theory, we used the ground penetrating radar (GPR) to find out the loose and caving scale in the burning area during the control process of the burning area, and then located the fire-extinguishing boreholes within target which we used to control burning fire in the section. A mobile comprehensive fire prevention and extinguishing system based on the three-phase foam fire prevention and control technique was then adopted and conducted in the burning area which took only 9 months to extinguish the 227,000m2 of burning area of 9# coal. This control technology and experience will provide a very important reference to the control of other coalfield fire and hillock fire in the future.

Study on Effect of the Modified Hollow Microspheres on the Foam Ability and Stability of Fire Fighting Foam

In this paper, fluoroalkylsilane (F3C-(CF2)5-(CH2)2-Si (OC2H5)3, F-8261) was successfully used as surface modifier to prepare oleophobic hollow microspheres. Three-phase foam was directly fabricated by oleophobic hollow microspheres. The result shows that outstanding improvement in the stability and anti-burning properties of three-phase foam on oil were achieved through the oleophobic modification. The optimum reaction conditions were 12% of fire fighting protein，the addition of 50% of hollow microsphere and0.5% F-8261.

Study on Effect of the Modified Hollow Microspheres on the Foam Ability and Stability of Fire Fighting Foam

In this paper, fluoroalkylsilane (F3C-(CF2)5-(CH2)2-Si (OC2H5)3, F-8261) was successfully used as surface modifier to prepare oleophobic hollow microspheres. Three-phase foam was directly fabricated by oleophobic hollow microspheres. The result shows that outstanding improvement in the stability and anti-burning properties of three-phase foam on oil were achieved through the oleophobic modification. The optimum reaction conditions were 12% of fire fighting protein，the addition of 50% of hollow microsphere and0.5% F-8261.

Research on Working Face of Residual Coal Self-Ignition Characteristics and Early Warning Technology

Development of air leakage in goaf and residual coal self-ignition Characteristics Study on the spontaneous combustion of residual coal in goaf in the early prediction, prevention and control management has very important significance. Based on the mining coal working surface pressure energy distribution and Sign gas detection of Nanzhuang coal mine working face within the airtight air leakage condition and the O2, CO, CO2, C2H6, C2H4, C3H8 and other Sign gas concentration variation, identified 4601, 8808 lane closed walls within Coal body broken belt of spontaneous combustion danger area and its morphology. According to the spontaneous combustion of residual coal in goaf features from strengthening ventilation management, strengthening the gas and temperature detection, perfusion of three-phase foam developed a comprehensive system for the prevention and control of coal spontaneous combustion