Search Results (27)

Fractured vuggy reservoirs exhibit intricate fracture networks, where large fractures impose significant shielding effects on smaller ones, posing formidable challenges for efficient exploitation. A systematic evaluation of foaming volume, drainage half-life, decay behavior, and viscosity under varying temperatures and salinities was conducted for conventional foam, polymer-enhanced foam, and gel foam. The results yield the following conclusions: Compared to conventional foam, polymer-enhanced foam exhibits markedly improved stability. In contrast, gel foam, cross-linked with chemical agents, maintains stability for over one week at elevated temperatures, albeit at the expense of reduced foaming capacity. The three-dimensional network structure formed post-gelation enables gel foam to retain a thicker liquid film, exhibiting exceptional foam stability. As salinity increases, the base liquid viscosity of conventional foam remains largely unaffected, whereas polymer foam shows marked viscosity reduction. Gel foam displays a non-monotonic viscosity response—initially increasing due to ionic cross-linking and subsequently declining from excessive charge screening. All three systems exhibit significant viscosity decreases under high-temperature conditions. Visualized plate fracture model experiments revealed distinct flow patterns and mobility control performance; narrow fractures exacerbate bubble coalescence under shear stress, leading to enlarged bubble sizes and diminished plugging efficiency. Among the three systems, gel foam exhibited superior mobility control characteristics, with uniform bubble size distribution and enhanced stability. Integrating the findings from the foam mobility control experiments in parallel fracture systems with the diversion outcomes of mobility control and flooding, distinct performance trends emerge. It can be seen that the stronger the foam stability, the stronger the mobility control ability, and the easier it is to start the shielding effect. Combined with the stability of different foam systems, understanding the mobility control ability of a foam system is the key to increasing the sweep coefficient of a complex fracture network and improve oil-washing efficiency. Full article

Pulque is an ethnic and traditional fermented beverage produced and consumed in Mexico; it is obtained from certain varieties of Agave, and its final alcohol content is around 4% to 7%. It is rich in protein and its carbohydrate content brings it a characteristic flavor; also, some probiotic bacteria are present in pulque. On the other hand, foams are a colloid system where the air bubble phase is dispersed in a continuous liquid phase. The foaming of liquids has been recognized as a method that shortens processes such as drying and preserves quality attributes. The present work studied the drainage kinetics of different pulque foams prepared with egg white in order to obtain a product suitable for further drying. Different egg white and pulque concentrations, as well as mixing times, were evaluated. The drainage volume was recorded and foam density was determined among different experiments. It was found that the lowest volume was drained when mixing for 20 min, and the lowest foam density was obtained when egg white and pulque were mixed in a 2:1 ratio. The drainage kinetics of the foam determines important information for its further use in a new product with pulque. Full article

Nanoparticles (NPs) have shown great potential in stabilizing foam for enhanced oil recovery (EOR). However, conventional NPs are difficult to recover and may contaminate produced oil, increasing operational costs. In contrast, superparamagnetic Fe₃O₄ NPs can be efficiently recovered using external magnetic fields, offering a sustainable solution for foam stabilization. In this study, Fe₃O₄ NPs were coated with SiO₂ using tetraethyl orthosilicate (TEOS) and further modified with dodecyltrimethoxysilane to enhance their hydrophobicity. The modification effects were characterized, and the optimal foam-stabilizing Fe₃O₄@SiO₂ NPs were found to have a contact angle of 77.01°. The foam system formed with α-olefin sulfonate (0.2 wt%) as the foaming agent and the optimal modified NPs exhibited a drainage half-life of 452 s. After foam-stabilization experiments, the NPs were recovered and reused, with the results indicating that three recovery cycles were optimal. Finally, visual microscopic displacement experiments demonstrated that the foam stabilized by modified NPs effectively mobilized clustered, membranous, and dead-end residual oil, increasing the recovery rate by 17.01% compared with unmodified NPs. This study identifies key areas for future investigation into the application of magnetic nanoparticles for enhanced oil recovery. Full article

Gangue particle entrainment during flotation remains a significant challenge in mineral processing. Previous studies have shown that incorporating inclined plates into the froth zone can reduce the recovery of fine gangue particles. However, the effects of inclined channels on froth drainage have not been fully investigated. This study employed a custom-designed forced drainage system to systematically examine the impact of inclined channels on foam drainage and the underlying mechanisms. Results revealed that, at an SDS solution injection flow rate of 36 mL/min and an inclined channel angle of 30°, the foam drainage velocity in the inclined channel was significantly higher than that in the vertical channel for both two-phase and three-phase foams. This advantage became more pronounced as the SDS injection flow rate increased. A new drainage pathway formed between the inclined wall and the foam, facilitating faster liquid flow than within the foam structure. This mechanism was identified as the primary factor enhancing foam drainage velocity in inclined channels. These findings demonstrate that inclined channels can effectively improve foam drainage efficiency compared to vertical channels, providing valuable insights for optimizing froth zone structure. Full article

Nitrogen foam is a promising enhanced oil recovery (EOR) technique with significant potential for tertiary oil recovery. This improves the efficiency of the oil displacement during the gas drive processes while expanding the swept volume. However, in the high-temperature, high-salinity reservoirs of the Tahe Oilfield, conventional N₂ foam systems show suboptimal performance, as their effectiveness is heavily limited by temperature and salinity. Consequently, enhancing the foam stability under these harsh conditions is crucial for unlocking new opportunities for the development of Tahe fracture-vuggy reservoirs. In this study, the Waring–Blender method was used to prepare weathered coal particles as a foam stabilizer. Compared to conventional foam stabilizers, weathered coal particles were found to enhance the stability of the liquid film under high-temperature and high-salinity conditions. Firstly, the foaming properties of the six foaming agents were comprehensively evaluated and their foaming properties were observed at different concentrations. YL-3J with a mass concentration of 0.7% was selected. The foaming stabilization performance of four types of solid particles was evaluated and weathered coal solid particles with a mass concentration of 15% and particle size of 300 mesh were selected. Therefore, the particle-reinforced foam system was determined to consist of “foaming agent YL-3J (0.7%) + weathered coal (15.0%) + nitrogen”. This system exhibited a foaming volume of 310 mL at 150 °C and salinity of 210,000 mg/L, with a half-life of 1920 s. Finally, through interfacial tension and viscoelastic modulus tests, the synergistic mechanism between weathered coal particles and surfactants was demonstrated. The incorporation of weathered coal particles reduced the interfacial tension of the system. The formation of a skeleton at the foam interface increased the apparent viscosity and viscoelastic modulus, reduced the liquid drainage rate from the foam, and mitigated the disproportionation effect. These effects enhanced the temperature, salinity resistance, and stability of the foam. Consequently, they contributed to the stable flow of foam under high-temperature and high-salinity conditions in the reservoir, thereby improving the oil displacement efficiency of the system. Full article

In recent decades, numerous studies have focused on finding environmentally friendly substitutes for commonly used petrochemical-based compounds. This paper explores the potential use of poly-L-lysine/rhamnolipids and poly-L-glutamic acid/ethyl lauroyl arginate mixtures, for foam formation and stabilization. Two complementary methods were employed to investigate the synergistic and antagonistic effects of these mixed polyelectrolyte/surfactant systems: (1) the thinning and rupture of thin foam films formed under dynamic conditions were monitored using a dynamic fluid-film interferometer (DFI), and (2) foamability tests were conducted using a standard dynamic foam analyzer (DFA). The results demonstrated that adding polyelectrolyte to an oppositely charged surfactant primarily induces a synergistic effect, enhancing foaming properties and extending foam lifetime. Furthermore, interferometric methods confirmed improved stability and slower drainage of thin foam films in systems containing synthetic polypeptides. Full article

Foam drainage agents enhance gas production by removing wellbore liquids. However, due to the ultra-high salinity environments of the Hechuan gas field (salinity up to 32.5 × 10⁴ mg/L), no foam drainage agent is suitable for this gas field. To address this challenge, we developed a novel nanocomposite foam drainage system composed of quaternary ammonium and two types of nanoparticles. This work describes the design and synthesis of a quaternary ammonium foam drainage agent and nano-engineered stabilizers. Nonylphenol polyoxyethylene ether sulfosuccinate quaternary ammonium foam drainage agent was synthesized using maleic anhydride, sodium chloroacetate, N,N-dimethylpropylenediamine, etc., as precursors. We employed the Stöber method to create hydrophobic silica nanoparticles. Carbon quantum dots were then prepared and functionalized with dodecylamine. Finally, carbon quantum dots were incorporated into the mesopores of silica nanoparticles to enhance stability. Through optimization, the best performance was achieved with a (quaternary ammonium foam drainage agents)–(carbon quantum dots/silica nanoparticles) ratio of 5:1 and a total dosage of 1.1%. Under harsh conditions (salinity 35 × 10⁴ mg/L, condensate oil 250 cm³/m³, temperature 80 °C), the system exhibited excellent stability with an initial foam height of 160 mm, remaining at 110 mm after 5 min. Additionally, it displayed good liquid-carrying capacity (160 mL), low surface tension (27.91 mN/m), and a long half-life (659 s). These results suggest the effectiveness of nanoparticle-enhanced foam drainage systems in overcoming high-salinity challenges. Previous foam drainage agents typically exhibited a salinity resistance of no more than 25 × 10⁴ mg/L. In contrast, this innovative system demonstrates a superior salinity tolerance of up to 35 × 10⁴ mg/L, addressing a significant gap in available agents for high-salinity gas fields. This paves the way for future development of advanced foam systems for gas well applications with high salinity. Full article

This study investigated the enhancing effects of the temperature-resistant polymer Poly(ethylene-co-N-methylbutenoyl carboxylate-co-styrenesulfonate-co-pyrrolidone) (hereinafter referred to as Z364) on the performance of cocamidopropyl hydroxy sulfobetaine (CHSB) foam under high-temperature and high-salinity conditions. The potential of this enhanced foam system for mobility control during heavy oil thermal recovery processes was also evaluated. Through a series of experiments, including foam stability tests, surface tension measurements, rheological assessments, and parallel core flooding experiments, we systematically analyzed the interaction between the Z364 polymer and CHSB surfactant on foam performance. The results indicated that the addition of Z364 significantly improved the strength, thermal resistance, and salt tolerance of CHSB foam. Furthermore, the adsorption of CHSB on the polymer chains enhanced the salt resistance of the polymer itself, particularly demonstrating stronger blocking effects in high-permeability cores. The experimental findings showed that Z364 increased the viscosity of the liquid film, slowed down liquid drainage, and reduced gas diffusion, effectively extending the half-life of CHSB foam and improving its stability under high-temperature conditions. Additionally, in parallel core flooding experiments, the polymer-enhanced foam exhibited significant flow diversion effects in both high-permeability and low-permeability cores, effectively directing more fluid into low-permeability channels and improving fluid distribution in heterogeneous reservoirs. Overall, Z364 polymer-enhanced CHSB foam demonstrated superior mobility control during heavy oil thermal recovery, offering new technical insights for improving the development efficiency of high-temperature, high-salinity reservoirs. Full article

The dilute-foam dispersion system improves oil recovery by reducing interfacial tension between oil and water, altering wettability, and diverting displaced fluids by plugging larger pores. An optimized foaming system is obtained by formability evaluation experiments, in which the half-life for drainage and foaming volume by different types and concentrations of surfactants are analyzed, followed by the addition of partially hydrolyzed polyacrylamide (HPAM) with varied concentrations to enhance the foam stability. Using COMSOL Multiphysics 5.6 software, the Jamin effect and plugging mechanism of the water–gas dispersion system in narrow pore throats were simulated. This dispersion system is applied to assist CO₂ huff-n-puff in a low-permeability core, combined with the online NMR method, to investigate its effects on enhanced oil recovery from the pore scale. Core-flooding experiments with double-pipe parallel cores are then performed to check the effect and mechanism of this dilute-foam dispersion system (DFDS) on enhanced oil recovery from the core scale. Results show that foam generated by combining 0.6% alpha-olefin sulfonate (AOS) foaming agent with 0.3% HPAM foam stabilizer exhibits the strongest foamability and the best foam stability. The recovery factor of the DFDS-assisted CO₂ huff-n-puff method is improved by 6.13% over CO₂ huff-n-puff, with smaller pores increased by 30.48%. After applying DFDS, the minimum pore radius for oil utilization is changed from 0.04 µm to 0.029 µm. The calculation method for the effective working distance of CO₂ huff-n-puff for core samples is proposed in this study, and it is increased from 1.7 cm to 2.05 cm for the 5 cm long core by applying DFDS. Double-pipe parallel core-flooding experiments show that this dispersion system can increase the total recovery factor by 17.4%. The DFDS effectively blocks high-permeability layers, adjusts the liquid intake profile, and improves recovery efficiency in heterogeneous reservoirs. Full article

China is rich in high-grade coalbed methane resources, accounting for one-third of the total amount of coalbed methane resources. Qinshui Basin is the main high ranking coalbed methane mining basin in China. In the early stage of CBM development, low-production and low-efficiency wells were formed in the process of block development because of an insufficient understanding of reservoir geological conditions. The existence of low-yield and low-efficiency wells with low output and a poor development benefit seriously restricts the efficient development of coalbed methane. In order to improve the overall development efficiency of coalbed methane fields, how to revitalize low-yield and low-efficiency wells is the main problem facing the development process of coalbed methane. With the deepening understanding of the study area geology, the formation of low-yield and low-efficiency wells has been basically identified. With the advancement of development technology, developers have the ability to retrofit some low-producing and inefficient wells. Low-production and low-efficiency wells are widely distributed. It is difficult to find the criteria for classifying low-producing and low-efficiency wells because of the great differences in geological conditions and reservoir physical properties in different blocks. In addition, the causes of a low-production and low-efficiency well are complex, as the same well is often caused by many reasons, and how to identify the causes of low-production and low-efficiency wells is difficult. In recent decades, developers have studied many methods to retrofit low-production wells, but the retrofit results are not satisfactory. How to choose an economical and efficient reservoir reconstruction method to revitalize low-production and low-efficiency wells is particularly important. This paper starts with the definition of low-production and low-efficiency wells in different blocks, combining an economic evaluation and productivity characteristics to judge whether they are low-production and low-efficiency wells, and defines the distribution of low-production and low-efficiency wells in blocks. The reasons for the formation of low-production and low-efficiency wells are analyzed with the geological characteristics, production dynamic performance, and engineering reconstruction effects. This paper makes a comparative analysis of the current relatively mature low-production and low-efficiency well treatment measures, clearly identifies the advantages and disadvantages of different treatment measures, and takes corresponding stimulation measures for different causes of low-production and low-efficiency wells. The research shows that there are 687 low-production and low-efficiency wells in block A, accounting for 69.4% of the total number of wells, and the low-production and low-efficiency wells account for a relatively large proportion; so, it is necessary to treat them. The main causes of low-production and low-efficiency wells are geology, engineering and drainage systems. The geological reason mainly refers to the low gas production of coalbed methane wells influenced by three factors: resource abundance, faults, and collapse columns. According to the different causes, three treatment measures of large-scale secondary fracturing, temporary plugging, and diversion fracturing and foam fracturing are put forward. The research method in this paper is targeted at different geological conditions so it can be used to guide the treatment of low-yield and low-efficiency wells in other CBM blocks, and it has very important significance for revitalizing the existing low-efficiency CBM assets and improving the development efficiency of CBM. Full article

Surfactants play a pivotal role in daily life owing to their commendable performance. The outbreak of the COVID-19 pandemic notably escalated surfactant usage. Upon entering building drainage systems with wastewater, surfactants profoundly influence hydraulic performance, an aspect that has garnered limited scholarly attention. This study employs an equally proportioned drainage test device to meticulously examine the variances in physical properties between surfactants, such as sodium dodecyl benzene sulfonate (SDBS) and alkyl ethoxylate-9 (AEO-9), and their repercussions on the hydraulic dynamics of building drainage horizontal main drains. Our findings reveal that the introduction of surfactants leads to the following: (1) an augmentation in water velocity and deposition distances of the solid simulant in the building drainage horizontal main drain with concentrations exacerbating this effect. The deposition distance of the solid simulation surged by up to 527% under experimental conditions compared to no surfactant; (2) there was a suppression of hydraulic jump and full degree of the horizontal main drain, with the concentration amplifying this suppression; and (3) an exacerbation of positive pressure in the horizontal main drain was found with increasing concentration, reaching a staggering 235.3% elevation compared to no surfactant. Moreover, SBDS foam outperformed AEO-9, demonstrating a 17.70–36.04% higher positive pressure in the horizontal main pipes. SBDS exhibits lower starting and ultimate viscosity, along with smaller colloid particle sizes, resulting in a 0.9–2.0% reduction in hydraulic jump and full degree. However, its inferior drag-reduction capability leads to a 17.48–36.44% decrease in the final deposition distances of solid simulant in the building drainage horizontal main drain compared to AEO-9. Full article

Foam is a medium-stable system composed of gas and liquid phases, which has the advantages of low density at the gas phase and high viscosity at the liquid phase, and has a wide application in oil and gas field development and mineral flotation, but its special medium-stable system also brings many problems in industry applications. Scientists have carried out extensive analyses and research on the foam stability and bubble-bursting mechanism, which initially clarified the rules of bubble breakage caused by environmental factors such as temperature and pressure, but the mechanism of bubble bursting under the action of internal factors such as liquid mineralization and oil concentration of the films is still not clearly defined. In this paper, we propose a compound salt-resistant foaming agent, investigated the influence of the aggregation and adsorption behavior of oil droplets on the liquid films and boundaries, and established a relevant aggregation and adsorption model with the population balance equation. We put forward a liquid film drainage mechanism based on the distribution, aggregation, and transport of oil droplets in the liquid films, so as to explain the changes in foam stability under the action of oil droplets. On the other hand, the viscoelastic analysis of foam fluid is performed with a rheometer, and the results show that in comparison with conventional power-law fluid, foam fluid has a complex rheological behavior for low shear thickening, but high shear thinning. Full article

The first botanical gardens in Europe were established for the study of medicinal, poisonous, and herbal plants by students of medicine or pharmacy at universities. As the natural sciences became increasingly important in the 19th Century, botanical gardens additionally took on the role of public educational institutions. Since then, learning from living nature with the aim of developing technical applications, namely biomimetics, has played a special role in botanical gardens. Sir Joseph Paxton designed rainwater drainage channels in the roof of the Crystal Palace for the London World’s Fair in 1881, having been inspired by the South American giant water lily (Victoria amazonica). The development of the Lotus-Effect^® at the Botanical Garden Bonn was inspired by the self-cleaning leaf surfaces of the sacred lotus (Nelumbo nucifera). At the Botanic Garden Freiburg, a self-sealing foam coating for pneumatic systems was developed based on the self-sealing of the liana stems of the genus Aristolochia. Currently, botanical gardens are both research institutions and places of lifelong learning. Numerous botanical gardens provide biomimetics trails with information panels at each station for self-study and guided biomimetics tours with simple experiments to demonstrate the functional principles transferred from the biological model to the technical application. We present eight information panels suitable for setting up education about biomimetics and simple experiments to support guided garden tours about biomimetics. Full article

Currently there is gaining interest in pre-compressed foam sealing tapes to seal joints watertight between different building envelope components. Little to no information is available on the parameters affecting the resistance of these foam tapes to driving rain. On the other hand, several research studies have shown that water leakages can be expected at relatively low-pressure differences and that drainage should be provided. Therefore, a study was designed to on the one hand assess the material and installation parameters that affect the watertightness of pre-compressed polyurethane foam sealing tapes impregnated with an acrylic polymer dispersion and on the other hand evaluate the potential of providing drainage possibilities, either as a two-barrier system or by means of integrated drainage cavities. It was found that the joint width, the presence of an airtight coating, and the position of the tape relative to the exterior surface affected the watertightness of the sealed joints. Notably, 87% of the evaluated foam tapes applied as a single barrier showed water leakages at pressure differences of 600 Pa or lower. Foam tapes with integrated drainage cavities, on the other hand, resulted in watertight joints up to an average pressure difference of 825 Pa. Full article

Foam acidization has unique advantages such as low damage, low filtration, low friction, high efficiency, excellent retardation, and fast liquid discharge rate, which is suitable for stimulation and reconstruction of low-pressure oil and gas reservoirs that have been developed over many years. It is obtained that the main chemical components of downhole plugging materials include vegetable oil, fatty acids and their esters, silicone oil, amide polymers, and additional organic components, as well as non-organic components, elemental sulfur, ferrous sulfide, iron disulfide, silicon dioxide, mineral salts, etc. The performance of foam acid was investigated by experiments, including the effective range of action of active acids, reducing filtration, increasing temperature resistance and high-temperature stability of foam acid deep wells. The new foam acid system is developed and optimized to suitable for low-pressure deep well acidification operations. Experimental evaluation optimized the acid foaming agent and foam stabilizer and developed a new foam acid formulation with foam stability, filter loss reduction, temperature resistance, and easy backflow performance. The experimental condition is that the temperature is 90 °C, the foam quality can reach more than 70% when mixed for more than 30 s, the average half-life is 38.75 min, and the liquid separation rate is 19.90 s/mL. Its suspension is better than that of conventional hydrochloric acid, its corrosion rate is 1.872 g/m²·h, and the flowback rate of foam acid residue reaches 97%. Experimental evaluation has shown that the developed foam acid features high surface activity, stable foam, strong temperature resistance, significant speed and corrosion suppression, and excellent drainage assist performance. Dynamical simulation evaluation of reservoir core foam acidification demonstrated that the foam features long-life, strong suspension capacity, excellent rheology, low filtration, and significant acidization and plug removal effects, and can be used in stimulating the medium-deep, high-temperature, and low-pressure oil and gas reservoirs. Full article