Search Results (674)

As oil and gas exploration advances, the development of deep, low-permeability, high-temperature, and high-salinity reservoirs poses increasing challenges. To address this, a novel amphoteric surfactant (TASS) was synthesized via free radical polymerization, and a high-performance water-based fracturing fluid system was developed. The system exhibited excellent thermal and salt resistance, with viscosity decreasing by less than 3.3% after 72 h at 150 °C and 20 wt% NaCl. It demonstrated clear shear-thinning behavior and strong elasticity. Interfacial activity tests showed that increasing NaCl concentrations reduced interfacial tension from 28.5 to 24.3 mN/m, while the contact angle on sandstone surfaces decreased significantly, indicating enhanced wettability and oil flow. Field applications further confirmed its effectiveness, with oil and gas production increasing by 81% and 133%, respectively, and a payback period of around 10 days. These results highlight the TASS fracturing fluid as a promising solution for stimulation in complex reservoirs. Unlike conventional betaine-type VES, the silane-grafted amphoteric design of TASS ensures viscosity retention at 220 °C and 25 wt% salinity. Full article

Lubricants play a crucial role in improving the reliability of internal combustion engines. The deterioration of engine oil is influenced not only by mileage and usage time but also by subjective factors. Currently, engine oil is replaced in accordance with the manufacturer’s recommendations. At the time of a scheduled oil change, two situations may arise: the degree of lubricant wear may exceed normal levels, in which case the technical systems may also be damaged, with serious consequences for the environment and, implicitly, for human health; or the degree of wear may be low, consistent with normal engine operation, in which case prolonging oil use is recommended, thereby reducing consumption. In this paper, the authors propose a method for diagnosing the engine through periodic analysis of the physico-chemical properties of used engine oil, based on which appropriate vehicle maintenance strategies are issued. Also, recommendations are made for prolonged use of the oil on the condition of its periodic evaluation. Thus, for samples taken from 43 trucks the following physico-chemical properties were analyzed: kinematic viscosity, density, flash point, fuel content, water content, and metal content and their values, for all samples, were within the recommended limits. However, for some samples, more pronounced variations in the values of some properties were found and suitable preventive maintenance recommendations were issued. Full article

In this study, low-viscosity (<5 mm²·s⁻¹, fits European Biodiesel Standard-EN 14214) quaternary microemulsification fuels were developed and tested in a CRDI diesel engine to evaluate their effects on engine performance, injection, combustion, and emission characteristics. The fuels were formulated using 50% petro-diesel, 30% waste frying oil (without converting biodiesel), and a combination of 10% n-butanol with either 10% methanol or 10% ethanol. Engine tests were conducted at constant speed of 2000 rpm and five different engine loads. The results indicated that both microemulsified fuels exhibited increased brake specific fuel consumption by about 20% and brake specific energy consumption by around 8% compared to petro-diesel, while thermal efficiency decreased by about 8%. Injection timing for both pilot and main injections occurred earlier with the emulsification fuels, and higher injection amount and injection rate values were observed at all loads. As engine load increased, the peak cylinder pressures of the emulsified fuels surpassed those of petro-diesel, although the crank angles at which these peak values were attained were similar. The combustion duration was shorter for both quaternary fuels, with similar maximum pressure rise rates to petro-diesel. Emulsification fuels caused higher exhaust emissions (especially THC) and this difference increased with increasing load. When comparing two formulations, the methanol-containing fuel demonstrated slightly better results than the ethanol-containing blend. These findings suggest that microemulsified fuels containing bio-alcohols and waste frying oil can be sustainable fuel alternatives for partial petro-diesel substitution if the injection settings are adapted in accordance with the properties of these fuels. Full article

Berry pomace is a valuable source of dietary fiber (DF) with promising applications in functional food development. This study aimed to evaluate and compare the technological and rheological properties of soluble (SDF) and insoluble (IDF) fiber fractions isolated from cranberry, black currant, lingonberry, and sea buckthorn pomace. SDF fractions demonstrated higher water solubility and lower swelling capacity, compared with IDF fractions. Meanwhile, water and oil retention capacities depended on fiber type and the sources of pomace. Fractionation notably affected color parameters, with SDFs generally being lighter. Rheological analysis revealed pseudoplastic, shear-thinning behavior in all SDF samples, with viscosity dependent on both pH and shear rate. In particular, the black currant SDF demonstrated higher yield stress compared to other SDFs, suggesting enhanced resistance to deformation and superior structural stability under low shear conditions. The consistency coefficient varied across samples, indicating differences in gel-forming potential. These findings highlight the importance of berry source and fiber fraction in determining functionality. The distinct hydration, binding, and rheological properties suggest that both SDF and IDF from berry pomace can be strategically applied as thickeners, stabilizers, or texture enhancers in food systems. This study supports the valorization of berry by-products as sustainable and functional ingredients in the formulation of fiber-enriched foods. Full article

Tight gas reservoirs, as important unconventional natural gas resources, face low recovery rates due to low porosity, low permeability, and strong heterogeneity. CO₂ Storage with Enhanced Gas Recovery (CSEGR) technology combines CO₂ geological storage with natural gas development, providing both economic and environmental benefits. However, the main controlling factors and influence mechanisms remain unclear. This study utilized the PR-EOS to investigate CH₄, CO₂, and natural gas physical properties, established a numerical simulation model considering CO₂ dissolution and geochemical reactions, and explored the influence of injection scheme, injection rate, production rate, and shut-in condition on CO₂ enhanced recovery and storage effectiveness through orthogonal design. Results show that CO₂ exhibits significant differences in compressibility factor, density, and viscosity compared to natural gas, enabling piston-like displacement. Intermittent injection slightly outperforms continuous injection in recovery enhancement, while continuous injection provides greater CO₂ storage capacity. The ranking of the significance of different influencing factors for enhanced oil recovery is as follows: injection rate > production rate > injection scheme > shut-in condition. For the effect of geological storage of CO₂, it is as follows: injection rate > injection scheme > production rate > shut-in condition. During gas injection, supercritical, ionic, and dissolved CO₂ continuously increase while mineral CO₂ decreases, with storage mechanisms dominated by structural and residual trapping. The study provides scientific basis for optimizing CO₂ flooding strategies in tight gas reservoirs. Full article

To the film thicknesses of grease-lubricated ball bearings, the viscosity of the base oil is considered in the Elastohydrodynamic Lubrication (EHL) equations. For very low speeds, the grease film thickness is much larger than the calculated base oil film thickness. Initially, the grease film thickness decreases with speed to a minimum value, followed by an increase, thus generating a “V-shape pattern”. To evidence this behavior of grease film in a ball bearing, the authors used the method of measuring electrical resistance. Using an oil with a viscosity close to a grease base oil viscosity, a relationship was obtained between the electrical resistance of the ball bearing and the average film thickness in the ball–race contacts. Based on this relationship, the variation in the grease film thickness was obtained by measuring electrical resistance at a bearing speed between 1 and 500 rpm for short running periods of 60 s. A “V-shape pattern” was evidenced with a minimum value of grease film thickness at around 10 rpm. Additionally, the electrical resistance methodology was considered, evidencing the good stability of the film thickness for long operation time at speeds between 200 rpm and 1500 rpm. After 8 running hours, minor fragmentation of the soap filaments was observed under the scanning electron microscope compared to the fresh grease structure, without affecting the thickness of the grease film. Full article

High-permeability emulsified asphalt has emerged as a promising prime coat for enhancing interlayer bonding in semi-rigid pavement structures. However, its widespread adoption remains limited by insufficient permeability and inconsistent mechanical properties. This study systematically investigated the effects of emulsifier ionic type (cationic or anionic), kerosene dosage (0–20%), and diluted asphalt content (corresponding to oil-water ratios of 5:5 and 4:6) on the comprehensive performance of high-permeability emulsified asphalt. Fundamental physical tests (sieve residue, evaporation residue, penetration, softening point, ductility), permeability evaluation, rotational viscosity measurements, and adhesion performance tests were conducted. Grey relational analysis (GRA) was employed to quantify the influence of each factor and their interactions on key performance metrics. The results reveal that anionic emulsifiers significantly improved low-temperature ductility and permeability. A low kerosene dosage (<10%) enhanced permeability and viscosity but compromised thermal stability at higher levels. Reducing the diluted asphalt content partially offset these adverse effects. GRA identified kerosene dosage as the dominant factor influencing permeability, softening point, and adhesion performance while emulsifier ionic type primarily affected ductility, and oil-water ratio strongly governed emulsification quality and viscosity. These findings provide quantitative insights for optimizing the composition of high-permeability emulsified asphalt and serve as a theoretical foundation for its engineering application in durable prime coats. Full article

Lubricating oil plays a critical role in protecting mechanical systems. Driven by sustainable development strategies, the development of high-performance, biocompatible green lubricants has become an urgent industry need. Biomass resources, characterized by wide distribution, renewability, and environmental friendliness, represent ideal raw materials for replacing petrochemical-based lubricants. In this study, renewable Xanthoceras sorbifolia oil was utilized as the feedstock. Branched modification was achieved via ring-opening esterification using 2-ethylhexanol (2-EH) as the modifier and tetrafluoroboric acid (HBF₄) as the catalyst. This epoxidation-branching modification process was synergistically combined with Nano-C₁₄MA/MMT treatment. This approach significantly reduced high-temperature kinematic viscosity loss while maintaining excellent low-temperature flow properties, resulting in an Xanthoceras sorbifolia oil-based lubricant with outstanding viscosity–temperature performance and low-temperature fluidity. At a Nano-C₁₄MA/MMT mass ratio of 0.3 wt% of the base oil, the lubricant demonstrated superior wide-temperature performance: KV₄₀ = 424.1 mm²/s, KV₁₀₀ = 50.8 mm²/s, VI = 180.8. The SP was reduced to −43 °C, exceeding the performance requirements of V-class environmentally friendly lubricants (e.g., synthetic ester oils). Furthermore, the coefficient of friction (COF) was 0.011 and the anti-wear scar diameter (AWSD) was 0.44 mm, indicating lubrication performance significantly superior to SN-class lubricants (specifications: COF < 0.12, AWSD < 0.50 mm). Full article

Background: Skin mycoses affect approximately 10% of the global population, and the range of effective topical antifungal agents remains limited. Voriconazole (VRC) is a broad-spectrum triazole with proven efficacy against drug-resistant fungal infections. This study aimed to develop and optimize VRC-loaded microemulsion (ME) polymer gels (Carbopol^®-based) for cutaneous delivery. Selected formulations also contained menthol (2%) as a penetration enhancer and potential synergistic antifungal agent. Methods: A comprehensive screening was performed using pseudoternary phase diagrams to identify stable oil/surfactant/co-surfactant/water systems. Selected MEs were prepared with triacetin, Etocas™ 35, and Transcutol^®, then gelled with Carbopol^®. Formulations were characterized for pH, droplet size, polydispersity index (PDI), and viscosity. In vitro VRC release was assessed using diffusion cells, while ex vivo permeation and skin deposition studies were conducted on full-thickness human skin. Rheological behavior (flow curves, yield stress) and texture (spreadability) were evaluated. Antifungal activity was tested against standard strain of Candida albicans and clinical isolates including a fluconazole-resistant strain. Results: The optimized ME (pH ≈ 5.2; droplet size ≈ 2.8 nm) was clear and stable with both VRC and menthol. Gelation produced non-Newtonian, shear-thinning hydrogels with low thixotropy, favorable for topical application. In ex vivo studies, performed with human skin, both VRC-loaded gels deposited the drug in the epidermis and dermis, with no detectable amounts in the receptor phase after 24 h, indicating retention within the skin. Menthol increased VRC deposition. Antifungal testing showed that VRC-containing gels produced large inhibition zones against C. albicans, including the resistant isolate. The VRC–menthol gel exhibited significantly greater inhibition zones than the VRC-only gel, confirming synergistic activity. Conclusions: ME-based hydrogels effectively delivered VRC into the skin. Menthol enhanced drug deposition and demonstrated synergistic antifungal activity with voriconazole. Full article

Mineral oil-based lubricants contain harmful elements, such as sulfur and phosphorus, pose significant harm to the environment. In current research on the application of waste oils and fats in bio-based lubricants, most studies focus on single pretreatment processes or additive preparation, lacking systematic investigations into the combined use of composite pretreatment and additives on lubricant performance. Moreover, the decolorization efficiency of traditional physical adsorption methods for treating waste oils and fats is limited, making it difficult to meet the raw material requirements for bio-based lubricants. The purpose of this study is to conduct composite pretreatment processes on waste oils and fats, understand the impacts of parameters such as additive dosage and environmental factors on lubricant performance, establish an environmentally friendly and performance-compliant preparation process for bio-based lubricants, and provide a theoretical basis and technical support for its industrial application. Recent studies have shown that new decolorization processes for waste oil treatment significantly improve decolorization and recovery rates, as evidenced by research comparing new and traditional methods. Pretreatment with hydrogen peroxide, activated clay, and activated carbon significantly improved the color and odor of treated waste oil, meeting standards for bio-based lubricant production. The intercalation polymerization reaction between ethyl cellulose (EC) and montmorillonite (MMT) was employed to develop an additive (CTAB-MMT/KH560-EC). A thorough investigation was performed to analyze the impact of temperature, processing time, and additive concentration on the rheological behavior. The bio-based lubricant exhibited a kinematic viscosity of 200.3 mm²/s at 40 °C and 28.3 mm²/s at 100 °C, meeting the standard conditions as outlined in ASTM D2270-10e1. This lubricant achieved an improved low-temperature performance with a pour point of −22 °C, a friction coefficient of 0.081, and an average pitting diameter of 0.94 mm, indicating its suitability for a range of applications. These lubricants exhibit outstanding viscosity characteristics, meeting the relevant requirements for energy and environmental applications in green, eco-friendly, and biodegradable sustainable development strategies while expanding their application scope. Full article

To investigate the time-varying influence of oil viscosity and water content on flow behavior in crossing pipelines, we developed a three-dimensional finite element/CFD model using advanced simulation software with fluid dynamics capabilities. Simulations were performed under varying viscosity and water-cut conditions, and the analyses covered fluid velocity, pressure distribution, and secondary flow characteristics. The results show clear quantitative trends: in the horizontal span, the stabilized centerline velocity reached 2.46 m/s (+23.0% versus the 2.00 m/s inlet). At Node 10, increasing viscosity from 0.306 to 0.603 Pa·s reduced the mean pressure by 11.2 kPa (−11.2% relative to a 0.10 MPa baseline), and a further increase to 1.185 Pa·s produced an additional 4.5 kPa (−4.5%) drop. At Node 1, the low-viscosity case yielded a centerline velocity 1.1× higher than the high-viscosity case (+10.0%). Consistent with these observations, higher viscosity and water cut decreased the average flow velocity and lengthened the duration of pressure fluctuations. These findings provide quantitative insight into the dynamic behavior of multiphase flow and offer a basis for understanding fluid–structure interaction phenomena in crude oil pipeline transport systems. Full article

The Pinghu Oil and Gas Field in the East China Sea Shelf Basin represents a significant offshore hydrocarbon-producing region in East Asia. However, the Paleogene hydrocarbon system in the Pinghu Oil and Gas Field is complex, and the fluid properties, charging stages, and hydrocarbon accumulation process are still unclear. A comprehensive integrated analysis of the hydrocarbon accumulation characteristics, fluid properties, temperature pressure regimes, primary hydrocarbon sources and origins (genesis), charging stages, preservation conditions, and evolutionary history of hydrocarbon accumulation have been studied by utilizing a series of well data, oil and gas geochemical parameters, carbon isotope, and fluid inclusion analyses. Hydrocarbon charging in the Huagang Formation experienced one stage, and the crude oil is characterized as light and conventional, exhibiting low density and viscosity, a low pour point, and low contents of wax, resin, and sulfur. In contrast, the reservoir of the overpressured Pinghu Formation experienced a two-stage hydrocarbon charging process (oil filling and gas filling), exhibiting higher density, viscosity, and wax content compared to the Huagang Formation. The hydrocarbon charging and evolution process of the Pinghu Formation and Huagang Formation in the Pinghu Oil and Gas Field can be summarized in three different stages, including the oil filling period (10–5 Ma), gas filling period (5–2 Ma), and oil and gas adjustment period. The Pinghu Oil and Gas Field, especially in the lower Pinghu Slope Belt (Fangheting Structure), has good potential for further exploration. Full article

Mayonnaise is a widely consumed food emulsion. Traditional mayonnaise contains approximately 70–80% lipids, making it a high-fat, calorie-dense food. This study aimed to develop a reduced-fat mayonnaise with physicochemical properties comparable to commercial low-fat formulations but with a lower oil content (<30%). Three formulations were prepared using canola oil and high-oleic sunflower oil at different concentrations (10%, 15%, and 30%), with and without the addition of synthetic antioxidants (BHA and BHT). Guar gum was used to control the viscosity of the continuous phase, adjusting its concentration between 0.75% and 1.55%. The formulations were compared with a commercial low-fat sample (MH) in terms of flow and rheological properties, color, phase separation stability, particle size, microscopy, and oxidative stability. The formulations exhibited flow behavior and Konini’s viscosity similar to MH. The 15% oil formulation (MHO-15%) had a particle size comparable to MH. Both MH and the experimental formulations exhibited a weak gel structure. To achieve the characteristic yellow color, β-carotene should be added to MHO-15%. Formulations containing canola oil and those without antioxidants showed higher susceptibility to oxidation, leading to the selection of high-oleic oil with added antioxidants. Based on these findings, a potential reduced-fat mayonnaise-type sauce could be formulated by decreasing lipid content from 30% to 15%. Full article

During machining, most of the mechanical energy is converted into heat. A substantial part of this heat is transferred to the cutting tool, causing a rapid rise in tool temperature. Excessive thermal loads accelerate tool wear and lead to displacement of the tool center point, reducing machining accuracy and workpiece quality. This challenge is particularly pronounced when machining titanium alloys. Due to their low thermal conductivity, titanium alloys impose significantly higher thermal loads on the cutting tool compared to conventional carbon steels, making the process more difficult. To reduce temperatures in the cutting zone, cutting fluids are widely employed in titanium machining. They have been shown to significantly extend tool life. Cutting fluids are broadly categorized into cutting oils and water-based cutting fluids. Owing to their distinct thermophysical properties, these fluids exhibit notably different cooling and lubrication performance. However, current research lacks comprehensive cross-comparative studies of different cutting fluid types, which hinders the selection of optimal cutting fluids for process optimization. This study examines the influence of three cutting fluids—emulsion, cutting oil, and synthetic oil-free fluid—on tool wear, temperature, surface quality, and energy consumption during flood-cooled end milling of Ti-6Al-4V. A novel experimental setup incorporating embedded thermocouples enabled real-time temperature measurement near the cutting edge. Tool wear, torque, and surface roughness were recorded over defined feed lengths. Among the tested fluids, emulsion achieved the best balance of cooling and lubrication, resulting in the longest tool life with a feed travel path of 12.21 m. This corresponds to an increase of approximately 200% compared to cutting oil and oil-free fluid. Cutting oil offered superior lubrication but limited cooling capacity, resulting in localized thermal damage and edge chipping. Water-based cutting fluids reduced tool temperatures by over 300 °C compared to dry cutting but, in some cases, increased notch wear due to higher mechanical stress at the entry point. Power consumption analysis revealed that the cutting fluid supply system accounted for 60–70% of total energy use, particularly with high-viscosity fluids like cutting oil. Complementary thermal and CFD simulations were used to quantify heat partitioning and convective cooling efficiency. The results showed that water-based fluids achieved heat transfer coefficients up to 175 kW/m²·K, more than ten times higher than those of cutting oil. These findings emphasize the importance of selecting suitable cutting fluids and optimizing their supply to enhance tool performance and energy efficiency in Ti-6Al-4V machining. Full article

Meandering river point bar sand bodies, serving as critical reservoir units, exhibit significant lithofacies heterogeneity that governs remaining oil distribution patterns. Taking the Guantao Formation in the Gudao Oilfield as an example, this study integrates core observation, pore-throat structure characterization, and numerical simulation to reveal lithofacies characteristics of point bar sand bodies and their controlling mechanisms on incremental oil recovery distribution during surfactant–polymer (SP) flooding. The results demonstrate that point bar lithofacies display planar grain-size fining from concave to convex banks, with vertical upward-fining sequences (point bar medium sandstone facies → fine sandstone facies → siltstone facies). Physical property variations among lithofacies lead to remaining oil enrichment in relatively low-permeability portions of fine sandstone facies and low-permeability siltstone facies after waterflooding. SP flooding significantly enhances remaining oil mobilization through a “lithofacies-controlled percolation—chemical synergy” coupling mechanisms. The petrophysical heterogeneity formed by vertical lithofacies assemblages in the reservoir directly governs the targeted zones of chemical agent action (with interfacial tension reduction preferentially occurring in high-permeability lithofacies, while viscosity control dominates sweep enhancement in low-permeability lithofacies). This results in a distinct spatial differentiation of the incremental oil recovery, characterized by a spindle-shaped sweep improvement zone and a dam-type displacement efficiency enhancement zone. Full article