Search Results (240)

This study addresses the challenges of low-pressure oil well workover operations, namely, severe loss of water-based workover fluid, significant reservoir damage from conventional temporary plugging agents, and slow production recovery, by focusing on the yet-mechanistically unclear “fuzzy-ball workover fluid.” Laboratory experiments combined with field data were used to evaluate its plugging performance and reservoir-protective mechanisms. In sand-filled tubes (diameter 25 mm, length 20–100 cm) sealed with the fuzzy-ball fluid, the formation’s bearing capacity increased by 3.25–18.59 MPa, showing a positive correlation with the plugging radius. Compatibility tests demonstrated that mixtures of crude oil and workover fluid (1:1) or crude oil, workover fluid, and water (1:1:1) held at 60 °C for 80 h exhibited only minor apparent viscosity reductions of 4 mPa·s and 2 mPa·s, respectively, indicating good stability. After successful plugging, a 1% ammonium persulfate solution was injected for 2 h to break the gel; permeability recovery rates reached 112–127%, confirming low reservoir damage and effective gel-break de-blocking. Field data from five wells (formation pressure coefficients 0.49–0.64) showed per-well fluid consumption of 33–83 m³ and post-workover liquid production index recoveries of 5.90–53.30%. Multivariate regression established mathematical relationships among bearing capacity, production index recovery, and fourteen geological engineering parameters, identifying the plugging radius as a key factor. Larger radii enhance both temporary plugging strength and production recovery without harming the reservoir, and they promote production by expanding the cleaning zone. In summary, the fuzzy-ball workover fluid achieves an integrated “high-efficiency plugging–low-damage gel-break–synergistic cleaning” mechanism, resolving the trade-off between temporary-plugging strength and production recovery in low-pressure wells and offering an innovative, environmentally friendly solution for the sustainable and efficient exploitation of oil–gas resources. Full article

A series of high-viscosity ferrofluids with variations in particle concentration and carrier liquid molecular weight were synthesized in a fluoroether oil base by the chemical coprecipitation method. The microstructure, surface coating, and magnetic properties of the nanoparticles were characterized, and the rheological properties of the corresponding ferrofluids were systematically investigated to elucidate their governing mechanisms and underlying mechanisms. The results indicate that the synthesized zinc-doped ferrite particles are spherical with a size of less than 50 nm and are chemically coated with a fluoroether acid. Moreover, the saturation magnetization of the ferrofluids increases with rising particle concentration. With the increase in particle concentration, the zero-field viscosity and shear stress of the ferrofluids increase significantly. The zero-field viscosity and shear yield stress of the ferrofluid increase significantly with the molecular weight of the carrier liquid, due to the strengthened entanglement of its molecular chains. At a carrier liquid molecular weight of 4600 g/mol, the 50 wt.% ferrofluid displayed a liquid character, in contrast to the gel-like character displayed by the 60 and 70 wt.% samples. The 60 wt.%-7480 g/mol sample demonstrated superior elasticity to its 60 wt.%-4600 g/mol counterpart. Furthermore, the application of a 100 mT magnetic field induced a transition from a liquid to a gel state in the 50 wt.%-4600 g/mol sample. This transition, driven by the formation of magnetic field-induced chain-like structures, significantly enhanced the magnetoviscous effect. This study provides the theoretical basis and experimental support for the development of high-viscosity ferrofluid sealing materials suitable for high-pressure, liquid environments and corrosive working conditions. Full article

As one of the most important future energy solutions, liquid hydrogen has advantages in terms of high energy density, ease of storage and transportation, low cost, and high safety. Valves are critical components for liquid hydrogen systems; compared to other energy systems, liquid hydrogen systems require higher sealing performance for valves at working temperatures to ensure operational safety and efficiency. However, recent research either focuses on cryogenic valves for liquid nitrogen and higher temperature ranges or liquid hydrogen temperatures (−253 °C) with safety valves and small diameters (typically below DN50). In this work, the sealing performance of liquid hydrogen globe valves at design temperatures was investigated through the finite element method and experimental tests. The behavior of different sealing structures under liquid hydrogen conditions was observed by means of comparative numerical analysis. Furthermore, a test system for liquid hydrogen valves with diameters ranging from DN10 to DN100 was established, covering a size range that encompasses 80% of commercially available liquid hydrogen valve products. By employing an internal cooling method utilizing liquid helium to reach target temperatures, the valve leakage rates (both internal and external) were assessed using helium mass spectrometry. The test results indicated that valve leakage was recorded at only 25% of the maximum allowable leakage, thereby adhering to the standards set for liquid hydrogen valves. These test results provide actionable insights for optimizing valve design and advancing hydrogen energy infrastructure development. Full article

The ultrasonic sensor method is the most significant and widely accepted technique for measuring liquid levels in tanks. Ultrasonic waves are particularly advantageous in the case of explosive, flammable, or aggressive liquids because of the possibility of introducing ultrasonic pulses through the tank wall safely. Often, the measurement of these liquids should be performed automatically using electronic devices to ensure that the tank remains sealed. In the case of ultrasound, measurements are made using the echo method, with a transmitting-receiving (transceiver) ultrasonic transducer that sends vibration pulses into the tank. The measured delay between the transmitted pulse and the pulse reflected from the liquid surface is proportional to the liquid level in the tank. The volume of liquid can be calculated on the basis of the dimensions of the tank. In this method, it is very important to accurately determine the delay by detecting the beginning of the reflected pulse, which determines the accuracy of the measurement of the level of the liquid and its quantity in the tank. To improve this accuracy, this paper proposes the use of the Akaike Information Criterion (AIC) used in statistics for model selection. As part of the research, ultrasonic test measurements were performed for a tank filled with water and extraction gasoline. This allowed a favorable comparison of the AIC method with the most commonly used threshold method and for determining the accuracy of liquid volume measurements in the tank using both methods in relation to the parameters of several selected ultrasonic sensors. The accuracy obtained using the AIC method was found to be better than that of the fixed-fractional amplitude threshold method. Furthermore, the AIC method is more versatile because it is less sensitive to interference and is capable of detecting the onset of a pulse regardless of its shape and frequency, even in noise. It is suitable for real-time embedded systems for liquid level measurement as well. Full article

The environmental impact of petroleum-based plastics has accelerated the search for sustainable alternatives in food packaging. Polylactic acid (PLA), a biobased and compostable polymer, is among the most promising candidates, yet its inherent brittleness and poor moisture barrier limit its application in high-humidity contexts such as dairy packaging. This study investigates immiscible PLA/poly(butylene succinate-co-adipate) (PBSA) blend films as potential biobased packaging materials for perishable foods. Even if these blends have been already studied, limited attention has been given to the systematic characterization of the baseline barrier properties of unmodified PLA/PBSA blends in contact with liquid dairy products. Four blend ratios (PLA/PBSA = 30/70, 40/60, 50/50, 60/40 wt%) were prepared via micro-compounding and compression molding. The films were characterized through melt flow analysis, FTIR, SEM, DSC, DMTA, and tensile testing to evaluate their thermal, morphological, and mechanical properties. Crucially, moisture barrier performance was assessed under simulated dairy conditions by sealing fresh whey at 4 °C and monitoring weight loss over 30 days. Results revealed that while tensile strength and storage modulus (E’) decreased nearly linearly with increasing PBSA content, elongation at break exhibited a non-linear trend, highlighting the complex interplay between blend morphology and mechanical behavior. The study provides a baseline understanding of neat PLA/PBSA blends in contact with liquid dairy, identifying the most promising formulations for future scale-up. These findings contribute to the development of biodegradable packaging systems tailored for refrigerated, high-moisture food applications Full article

The magnetic fluid seal (MFS) is a novel sealing technique that offers numerous benefits such as non-wear, long life, zero leakage, etc. There are numerous potential applications for it in the fields of energy and chemical industry, aerospace, machinery and electricity, etc. However, compared with a mechanical seal, the pressure of MFS is relatively low, which greatly limits its application promotion. Therefore, in this paper, a magnetic fluid sealing device with a dual magnetic source (present MFS) is firstly designed to improve the sealing pressure. Secondly, the effects of different sealing gaps, pole tooth heights, pole tooth angles and pole tooth eccentricity distances on the sealing pressure are investigated through numerical simulations to obtain the better combination of structural parameters for sealing performance. Finally, a test rig was built to confirm the reliability of the new device, and the results show that the new device’s sealing pressure is significantly higher than the conventional MFS’ at the same rate of rotation, with a maximum increase of 1.69 times and 1.71 times in sealing gas and liquid, respectively. This paper provides a reference for the improvement of sealing pressure of MFS in engineering applications. Full article

Fractured lost circulation remains a major drilling challenge due to low compatibility between conventional plugging materials and fractures. By utilizing thermosetting resin emulsification and high-temperature crosslinking coalescence, this study developed a temperature-activated nanomaterial enhanced liquid–solid phase transition plugging emulsion. The system adapts to varying fracture apertures, forming plugging particles with a broad size distribution and high strength upon thermal activation. The structural characteristics, mechanical properties, and fracture-plugging performance of the plugging particles were systematically investigated. Results demonstrate that the optimized system, comprising 8 wt.% emulsifier, 0.16 wt.% dispersant, 0.4 wt.% crosslinker, 0.4 wt.% viscosifier, 70 wt.% distilled water, and 2 wt.% nano-silica (all percentages relative to epoxy resin content), can produce particles with a size of 1–5 mm at formation temperatures of 80–120 °C. After 16 h of thermal aging at 180 °C, the particles exhibited excellent thermal stability and compressive strength, with D(90) degradation rates of 3.07–5.41%, and mass loss of 0.63–3.40% under 60 MPa. The system exhibits excellent injectability and drilling fluid compatibility, forming rough-surfaced particles for stable bridging. Microscopic analysis confirmed full curing in 140–180 min. Notably, it sealed 1–5 mm fractures with 10 MPa pressure, enabling adaptive plugging for unknown fracture apertures. Full article

As industry moves from fossil fuels to green energy, substituting hydrocarbons with hydrogen as an energy carrier seems promising. Hydrogen can be stored in salt caverns, depleted hydrocarbon fields, and saline aquifers. Among other criteria, these storage solutions must ensure storage safety and prevent leakage. The ability of a caprock to prevent fluid from flowing out of the reservoir is, thus, of utmost importance. In this review, the main factors influencing fluid flow are examined. These are the wettability of the caprock formation, the interfacial tension (IFT) between the rock and the gas or liquid phases, and the ability of gases to diffuse through it. To achieve effective sealing, the caprock formation should possess low porosity, a disconnected or highly complicated pore system, low permeability, and remain strongly water-wet regardless of pressure and temperature conditions. In addition, it must exhibit low rock–liquid IFT, while presenting high rock–gas and liquid–gas IFT. Finally, the effective diffusion coefficient should be the lowest possible. Among all of the currently reviewed formations and minerals, the evaporites, low-organic-content shales, mudstones, muscovite, clays, and anhydrite have been identified as highly effective caprocks, offering excellent sealing capabilities and preventing hydrogen leakages. Full article

To protect the environment, sequestering CO₂ during the extraction of natural gas hydrates is a highly promising carbon-neutral technology. We investigated methane extraction and CO₂ storage by a combined depressurization and CO₂-injection method. In the seabed environment, the hydrate-forming period is ~300 min. When injecting liquid carbon dioxide into the reservoir, a replacement rate of ~11.1% is insufficient to meet the requirements for extracting methane and sealing carbon dioxide. Increasing the depressurization pressure can increase gas production. However, an excessively large depressurization pressure will cause the permeability damage rate (PDR) to reach 76.40%, which is not conducive to the continuous progress of the project. Increasing the depressurization pressure (7 MPa) and extending the depressurization pressure time (3 h) can effectively increase the final hydrate saturation (HS) and protect the reservoir permeability. This means higher reservoir stability and more sealed carbon dioxide. A new method has been proposed, namely, the coupling of depressurization and CO₂ injection. This method actually extends the depressurization time, resulting in an average reservoir permeability of 1.72 millidarcies, thereby achieving a carbon dioxide storage rate of 27.7%. At the same time, it avoids the repeated implementation of pressure reduction and CO₂ injection, reducing the complexity of the project. Full article

HP, as an isotropic physical stress, has been widely applied in cell biology and reproductive research to simulate the effects of environmental pressure on cellular functions. In this study, the elastic silicone membrane of a novel bionic insemination catheter was employed as the pressure medium, with semen perfused into a sealed silicone chamber. As the silicone membrane underwent controlled deformation, the liquid inside the chamber generated a nearly uniform isotropic pressure, thereby maintaining spermatozoa in a stable HP environment. Boar sperm are susceptible to physiological and functional damage under HP stress, which can impair fertilization capacity. This study aimed to investigate the effects of TMAO, BET, or their combination on the quality of semen from eight Landrace boars under HP during storage at 17 °C (experiment repeated three times). Semen was collected using the manual collection method and treated with different concentrations of TMAO or BET. Sperm motility parameters were assessed using a CASA system to determine the optimal concentrations. Subsequently, experimental groups were established: the fresh group, HP control group, T group (optimal TMAO), B group (optimal BET), and H group (optimal TMAO + BET). The results showed that the optimal concentrations were 8 mmol/L for TMAO and 20 mmol/L for BET. Compared with the HP control group, the T, B, and H groups showed significantly improved sperm viability, mitochondrial membrane potential (MMP), and plasma membrane integrity (p < 0.05), and significantly reduced DFI, ROS, MDA, and NO contents (p < 0.05), while acrosome integrity showed no significant differences (p > 0.05). Additionally, the B group showed significantly increased T-AOC (p < 0.05). Non-targeted lipidomic analysis revealed 49 differential lipids in the T group, 262 in the B group, and 269 in the H group compared with the HP control. These differential lipids were mainly associated with PC, AcCa, and sphingolipid signaling pathways, with key sphingolipid pathway lipids including Cer, SM, and DG. These findings indicate that BET and TMAO + BET improve HP-induced sperm damage by modulating the sphingolipid signaling pathway and maintaining PC and AcCa levels, whereas TMAO alone may exert protective effects through additional mechanisms. In conclusion, TMAO, BET, or their combination effectively mitigates the detrimental effects of HP on boar sperm. Full article

Wellbore washing technology is a basic operation in wellbore maintenance. Problems such as low automation levels, long processing times, the fact that it is easy to cause downhole falling, and cleaning blind areas greatly affect the use and maintenance of traditional cleaning equipment. These problems usually come from design defects such as a complicated installation process, a lack of an anti-impact structure, and a fixed jet direction. To address the aforementioned issues, this paper proposes an efficient and integrated rapid-disassembly and -assembly automatic filtration rotary jet cleaning device. The device is divided into two main units and further subdivided into four modules. The quick-assembly unit comprises an elastic connection module and a downstroke quick-assembly module, which can automatically compensate for deviations in equipment position during the installation process, ensuring the reliability of the installation process and the sealing of the equipment and facilitating the rapid connection and separation of the tool string. The wellbore cleaning unit includes a hydraulic rotary washing module and a rotary filtration storage module. The wellbore is jet-flushed by hydraulic drive, and the solid particles are separated and filtered during the cleaning fluid circulation process to realize the purification and reuse of the cleaning fluid. The device reduces the installation operation time and labor cost, improves the reliability of equipment in the well, improves the flushing coverage area and the cleaning efficiency, realizes the reuse of the cleaning liquid in the wellbore, reduces the energy consumption of the flowback treatment, and comprehensively improves the cleaning efficiency and the energy utilization efficiency. Full article

A liquid-sealed single-mode–no-core–single-mode (SNS) structure fiber temperature sensor based on polyvinyl alcohol (PVA) partial replacement coating is proposed. Using a liquid-sealed glass capillary structure, the PVA solution is introduced into the SNS structure and avoids its influence by environmental humidity. Temperature can be obtained by measuring the shift of the multimode interference spectrum, which is affected by the thermal optical effect of the PVA solution. Through theoretical simulation of the sensor, the optimal NCF fiber length and coating stripped length are obtained by comprehensively considering the transmitted loss and output spectrum signal-to-noise ratio (SNR). The optimal PVA solution concentration is selected by measuring the thermo-optic coefficient (TOC) and refractive index (RI). Based on the theoretical optimization results, a PVA solution-coated SNS fiber optic temperature sensor is experimentally fabricated, and temperature-sensing characteristics are measured within −3.6 to 73.2 °C. The experimental results show that the sensor has a high sensitivity (nm/°C, maximum is 21.713 nm/°C) and has a resolution of 10⁻³ °C. ${\lambda }_{dip}$ has a stable negative linear relationship with temperature, and the correlation coefficient of the fitting curve exceeds 95%. The temperature cycling experiment and long-term stability test show that the temperature sensor has good repeatability and stability. The experimental results also show the nonlinear relationship between the temperature measurement range and sensitivity, clarify the important factors affecting the response performance of fiber temperature sensors, and provide important reference values for optical fiber temperature sensors. Full article

Ammonia (NH₃) emissions from swine manure pits contribute significantly to odor nuisance, health risks, and secondary PM_2.5 formation. This study assessed the pilot-scale performance of three source-control technologies: surface sealing with surfactant-based foam system (FOAM SYSTEM), swine manure wiping and removing system (WIPING SYSTEM), and belt-conveyor-based solid–liquid separator system (BELT SYSTEM). Each technology targets a different pathway in the ammonia generation process. The FOAM SYSTEM suppresses volatilization by forming a foam barrier at the air–liquid interface. The WIPING SYSTEM reduces precursor contact time by periodically removing feces. The BELT SYSTEM separates feces and urine upon excretion, inhibiting enzymatic ammonia formation. Among the individual systems, the BELT SYSTEM achieved the highest ammonia reduction efficiency of 91.7%, followed by the FOAM SYSTEM (73.6%) and WIPING SYSTEM (64.4%). The combined FOAM SYSTEM + BELT SYSTEM yielded the best performance with an ammonia reduction efficiency of 94.4%, showing modest synergy without operational interference. In contrast, the FOAM SYSTEM + WIPING SYSTEM configuration achieved 71.1%, slightly lower than the FOAM SYSTEM alone, likely due to foam disruption. Environmental sensitivity tests revealed that higher temperatures and alkaline pH elevated NH₃ emissions, whereas systems that maintained near-neutral pH, like the FOAM SYSTEM, demonstrated greater stability. These findings highlight the importance of integrating physical and source-control mechanisms while considering environmental variability for effective on-farm ammonia mitigation. Full article

Efforts to enhance the mechanical and physicochemical properties of conventional glass ionomer cement (GIC) are ongoing. This study aimed to evaluate the effect of incorporating varying concentrations of frankincense and myrrh liquids into conventional GIC on its microhardness and sealing ability. Frankincense and myrrh liquids were prepared by dissolving 25 g of each ground resin in 50 mL of distilled water at 60 °C and allowing the solutions to stand for 8 h. Five experimental groups were evaluated: Group A (conventional GIC), Group B (15% frankincense-modified GIC), Group C (25% frankincense-modified GIC), Group D (15% myrrh-modified GIC), and Group E (25% myrrh-modified GIC). Microhardness was evaluated using a Vickers hardness tester, and sealing ability was evaluated via interfacial gap measurements using scanning electron microscopy (SEM). SEM analysis revealed that all modified GIC groups exhibited significantly smaller interfacial gap sizes (Groups B–E: 6.1, 5.22, 5.9, and 5.34 µm, respectively) compared to conventional GIC (Group A: 6.88 µm). However, there were no statistically significant differences in microhardness among the groups (p > 0.5). The incorporation of 15% and 25% concentrations of frankincense or myrrh liquids into conventional GIC significantly improved sealing ability without compromising hardness. Full article

This study presents a microfluidic chip platform designed using a multiscale 3D printing strategy for fabricating microfluidic chips with integrated, high-resolution, and customizable membrane structures. By combining two-photon polymerization (2PP) for submicron membrane fabrication with liquid crystal display printing for rapid production of larger components, this approach addresses key challenges in membrane integration, including sealing reliability and the use of transparent materials. Compared to fully 2PP-based fabrication, the multiscale method achieved a 56-fold reduction in production time, reducing total fabrication time to approximately 7.2 h per chip and offering a highly efficient solution for integrating complex structures into fluidic chips. The fabricated chips demonstrated excellent mechanical integrity. Burst pressure testing showed that all samples withstood internal pressures averaging 1.27 ± 0.099 MPa, with some reaching up to 1.4 MPa. Flow testing from ~35 $\mathsf{\mu }$L/min to ~345 $\mathsf{\mu }$L/min confirmed stable operation in 75 $\mathsf{\mu }$m square channels, with no leakage and minimal flow resistance up to ~175 $\mathsf{\mu }$L/min without deviation from the predicted behavior in the 75 $\mathsf{\mu }$m. Membrane-integrated chips exhibited outlet flow asymmetries greater than 10%, indicating active fluid transfer across the membrane and highlighting flow-dependent permeability. Overall, this multiscale 3D printing approach offers a scalable and versatile solution for microfluidic device manufacturing. The method’s ability to integrate precise membrane structures enable advanced functionalities such as diffusion-driven particle sorting and molecular filtration, supporting a wide range of biomedical, environmental, and industrial lab-on-a-chip applications. Full article