Search Results (714)

In order to solve the problems of low calorific value and pipeline corrosion caused by high concentration of CO₂ in oil-associated gas, and promote the resource utilization of associated gas, this study used validated grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation to investigate the adsorption characteristics of 11 different topological structures (straight-channel MFI/BEA, cage-channel LTA/FAU/CHA) and cation types (Ca²⁺, Na⁺, H⁺) of commercial zeolites for CO₂ and alkanes (CH₄, C₂H₆, C₃H₈) at 0%~90% RH. The results showed that the CO₂ adsorption capacity of all zeolites decreased with increasing humidity, but straight-channel zeolites (ZSM5-300, BETA-25) had excellent moisture resistance, with only a 20.8% and 30.6% decrease in capacity at 90% RH, respectively. The performance of cage-channel zeolite drops sharply under high humidity. Topology structure and cation synergistically regulate separation efficiency, maintaining stable diffusion order in straight channels. Ca²⁺ enhances dry state capacity but is prone to hydrophilic failure. The adsorption heat of CO₂ on straight-channel zeolite is 25–38 kJ/mol, resulting in lower regeneration energy consumption. ZSM5-300 is preferred for PSA (CH₄/CO₂ kinetic separation coefficient of 809.52 at 90% RH), and NaFAU is preferred for TSA (CO₂ adsorption capacity of 3.6 mmol/g and selectivity of 502.6 at 90% RH). This study clarifies the core structure-activity relationship and provides key theoretical support for the decarbonization of oil-associated gas. Full article

The high energy consumption and cost of operation which result from substantial pressure losses during the transportation of crude oil over long-distance pipelines due to frictional drag created by turbulence are fundamental issues. In order to cope with such challenges, the current research intends to develop a simulation-based study that employs MATLAB R2016b and Minitab 21 to assess the effectiveness of drag-reducing agents (DRAs). An effective mathematical representation of the use of basic fluid mechanics with a semi-empirical correlation on the DRA performance is therefore created and its performance compared to actual pipeline data, showing good compatibility with experimental results. The findings show that DRA addition can produce a significant reduction in the pressure drop by 30–35% with an increase in the overall flow efficiency by 40–60%. Using 25 ppm DRA concentration at a Reynolds number of 323,159 enables an optimised prediction of 33.43% in drag reduction with an efficiency of 45.13%. Moreover, it is also found that there are considerable energy savings, flatter radial velocity profiles, and enhanced particle transport, which highlights the radical effect of DRAs on the hydrodynamics of flows. More importantly, it is determined that DRAs are one of the most effective and cost-efficient solutions to improve throughput and decrease the pumping power in the oil pipeline. However, further research is required to generalise the model to multiphase flows and use the newest optimisation algorithms to control the dosage dynamically. Full article

To address the limitation of existing research on engine oil filter structural parameters—overemphasizing pressure drop while neglecting internal flow uniformity and filter media utilization—this study establishes a three-dimensional Computational Fluid Dynamics (CFD) model of a pleated oil filter for a certain type. With other structural and material parameters fixed, nine inner diameter schemes (60–84 mm) and seven pleat number schemes (50–80) were designed to systematically investigate their effects on pressure drop, flow uniformity, and media utilization via numerical simulations and experimental validation. The results show that pressure drop decreases monotonically with increasing inner diameter, with smaller diameters being more sensitive to flow rate variations; flow uniformity improves nonlinearly, with severe jets and large dead zones causing poor uniformity for smaller diameters, while uniformity is significantly enhanced with larger diameters, though marginal benefits diminish after a critical threshold. In contrast, pressure drop increases monotonically with more pleats, and higher pleat numbers are more sensitive to resistance changes; flow uniformity follows a threshold effect—deteriorating gradually without extensive dead zones for fewer pleats (maintaining high utilization) but declining sharply beyond a threshold due to narrowed inter-pleat spacing inducing intense jets and expanded dead zones. Full article

Accurate measurement of wall shear stress (WSS) is essential for both fundamental and applied fluid dynamics, where it governs boundary-layer behavior, drag generation, and the performance of flow-control systems. Yet, existing WSS sensing methods remain limited by low spatial resolution, complex instrumentation, or the need for user-dependent calibration. This work introduces a method based on artificial intelligence (AI) and Oil-Film Interferometry, referred to as AI-OFI, that transforms a classical optical technique into an automated and sensor-like platform for local WSS detection. The method combines the non-intrusive precision of Oil-Film Interferometry with modern deep-learning tools to achieve fast and fully autonomous data interpretation. Interference patterns generated by a thinning oil film are first segmented in real time using a YOLO-based object detection network and subsequently analyzed through a modified VGG16 regression model to estimate the local film thickness and the corresponding WSS. A smart interrogation-window selection algorithm, based on 2D Fourier analysis, ensures robust fringe detection under varying illumination and oil distribution conditions. The AI-OFI system was validated in the high-Reynolds-number Long Pipe Facility at the Centre for International Cooperation in Long Pipe Experiments (CICLoPE), showing excellent agreement with reference pressure-drop measurements and conventional OFI, with an average deviation below 5%. The proposed framework enables reliable, real-time, and operator-independent wall shear stress sensing, representing a significant step toward next-generation optical sensors for aerodynamic and industrial flow applications. Full article

Background and Clinical Significance: Macular holes are rare in pediatric patients and most often result from blunt trauma, commonly from soccer-related injuries. These cases present unique challenges due to delayed presentation, tightly adherent hyaloid layers, and difficulties with postoperative positioning. Larger, chronic macular holes have low spontaneous closure rates and poorer surgical outcomes, necessitating advanced surgical approaches. Herein we report a case of chronic traumatic macular hole in a pediatric patient that closed with an internal limiting membrane (ILM) flap surgical technique with silicone oil tamponade. Case Presentation: A 15-year-old male patient presented with a history of blunt ocular trauma from a soccer ball one year prior, resulting in a large chronic macular hole. The decision was made to perform pars plana vitrectomy with an inverted ILM flap technique and silicone oil tamponade. To stabilize the ILM flap and prevent displacement, a novel technique involving the placement of a single drop of silicone oil on the retinal surface prior to complete silicone oil fill was employed. This “silicone oil drop” technique allowed for smoother propagation of the oil over the flap, effectively securing it without the need for additional manipulation or perfluorocarbon liquid. Postoperatively, the macular hole was closed, and the patient’s vision improved. Conclusions: This case highlights the potential benefits of the ILM flap technique in treating pediatric macular holes with utilization of silicone oil as not only a tamponade but as a method to stabilize the flap. Full article

With the deepening of oil and gas exploration and development into ultra-deep and ultra-high pressure environments, the pressure of wellhead equipment is becoming higher and higher. The sealing performance of the casing head hanger is directly related to the safety and reliability of the whole wellhead equipment. Firstly, based on the numerical simulation method, the sealing performance of three different metal seal rings—H-type, X-type, and U-type—under 175 MPa working conditions is compared and analyzed. The simulation results show that the sealing performance of the H-type metal sealing ring is better than that of the X-type and U-type. The parametric analysis method is further used to study the influence of the structural parameters of the convex radius and the bottom angle of the H-ring on its sealing performance. The results show that when the convex radius is designed to be 3 mm, and the bottom angle is 90°, the effective contact width reaches 5.91 mm, and the contact uniformity is the best. Finally, based on the H-type metal sealing ring sample trial-produced with optimized parameters, a 175 MPa nitrogen medium sealing pressure test was completed on an 8 1/8” all-metal sealed mandrel casing hanger. The test results show that the system pressure drop is 0.7 MPa during the 5-min pressure stabilization process, which has good sealing reliability. Full article

This study presents an eccentric pipe separator (EPS) designed according to the shallow pool principle and Stokes’ law as a compact alternative to conventional gravitational tank separators for offshore platforms. To investigate the internal oil-water flow characteristics and separation performance of the EPS, both field experiments with crude oil on an offshore platform and computational fluid dynamics (CFD) simulations were conducted, guided by dimensional analysis. Crude oil volume fractions were measured using a Coriolis mass flow meter and the fluorescence method. The CFD analysis employed an Eulerian multiphase model coupled with the renormalization group (RNG) k-ε turbulence model, validated against experimental data. Under the operating conditions examined, the separated water contained less than 50 mg/L of oil, while the separated crude oil achieved a purity of 98%, corresponding to a separation efficiency of 97%. The split ratios between the oil and upper outlets were found to strongly influence the phase distribution, velocity field, and pressure distribution within the EPS. Higher split ratios caused crude oil to accumulate in the upper core region and annulus. Maximum separation efficiency occurred when the combined split ratio of the upper and oil outlets matched the inlet oil volume fraction. Excessively high split ratios led to excessive water entrainment in the separated oil, whereas excessively low ratios resulted in excessive oil entrainment in the separated water. Crude oil density and inlet velocity exhibited an inverse relationship with separation efficiency; as these parameters increased, reduced droplet settling diminished optimal efficiency. In contrast, crude oil viscosity showed a positive correlation with the pressure drop between the inlet and oil outlet. Overall, the EPS demonstrates a viable, space-efficient alternative for oil-water separation in offshore oil production. Full article

Widely used in treating oil mist aerosols generated from metalworking processes, conventional gas–liquid coalescing filters face drawbacks such as increased energy consumption, performance limitations, and shortened service life due to high steady-state pressure drop. To address these issues, this study proposes an innovative design for a filter based on wettability-regulated gradient pore structure. Using glass fiber filter media with different pore size parameters as the substrate and incorporating an intermediate mesh layer, a three-layer filtration structure of “large-pore filtration layer—mesh layer—small-pore filtration layer” was constructed. The surface wettability of each layer was regulated by a self-developed surface modifier, producing gradient pore structure filters with different wettability configurations. The variations in key performance parameters, including steady-state pressure drop, filtration efficiency, saturation, and service life, were systematically evaluated for these configurations. Experimental results demonstrated that the configuration with an “oleophobic large-pore filtration layer—mesh layer—oleophilic small-pore filtration layer” yielded the best overall performance. Analysis based on the “jump-channel” model indicated that the gradient pore structure achieves progressive droplet filtration and optimizes droplet coalescence and capture through wettability differences. Consequently, while maintaining exceptional filtration efficiency (>99%), this configuration significantly reduces the steady-state pressure drop by over 34% and effectively extends the service life by more than 66%. This wettability-regulated gradient pore structure provides a novel technical pathway for addressing the challenges of balancing pressure drop and filtration efficiency, as well as extending the service life, in gas–liquid coalescing filters. Full article

Shale oil is primarily hosted within nanopores, where its flow behavior exhibits significant deviations from classical Darcy flow. The combined influences of nanoscale confinement and interfacial interactions represent key scientific challenges that hinder efficient shale oil recovery. The results show that under 25 °C and 1 MPa, the displacement distances of shale oil within 12 s in 100, 200, and 300 nm channels were 2.88, 5.67, and 11.01 mm, respectively. As pore size decreases, flow capacity drops sharply, and the displacement–time relationship evolves from quasi-linear to strongly nonlinear, indicating pronounced nanoscale non-Darcy behavior. By incorporating an equivalent resistance coefficient into the plate-channel flow model, the experimental data were accurately fitted, enabling quantitative evaluation of the additional flow resistance induced by nanoconfinement and interfacial adsorption. The equivalent resistance coefficient increases markedly with decreasing pore size but decreases progressively with increasing temperature and driving pressure. Increasing temperature and pressure partially mitigates nanoconfinement effects. In 200 nm channels, the equivalent resistance coefficient decreases from 1.87 to 1.20 as temperature rises from 25 to 80 °C, while in 100 nm channels it decreases from 2.43 to 1.65 as driving pressure increases from 1 to 6 MPa. Nevertheless, even under high-temperature and high-pressure conditions, shale-oil flow does not fully recover to ideal Darcy behavior. This work establishes a nanofluidic-based prediction and evaluation framework for shale oil flow, offering theoretical guidance and experimental reference for unconventional reservoir development and the optimization of enhanced oil recovery strategies. Full article

The “Double High—Double Extra High” stage of offshore oilfields, where large pumps lift liquids, leads to a rapid rise in water concentration, which triggers a decrease in rock strength and exacerbates the risk of sand production; this leads to a blockage of the reservoir, thus restricting the release of production capacity. In this paper, for the typical weak cementation strength of unconsolidated sandstone of a Class I reservoir in the P oilfield, numerical simulation and indoor experimental methods are utilized to explore the plugging mechanism and law of the water-contenting conditions, with micro-sand and mud conditions, on the screen. Considering the combined effects of reservoir particulate transport plugging and near-well sand control media plugging, the additional pressure drop and skin factor calculation model is constructed, and a dynamic capacity prediction model for sand control wells is formed. By matching the physical properties of the target reservoir and optimizing the sand control method, the production capacity prediction model and the sand control optimization design method for the high water-content period of the unconsolidated sandstone reservoir are finally obtained. The results show that the median sand size of well A1 in the P oilfield Class I reservoir is 220 μm, the sand transportation diameter is about 15–20 m, the serious plugging area near the well is distributed in 2–2.5 m, and the predicted loss of production capacity is about 18%. The use of a foam metal screen can significantly reduce the plugging pressure and increase the flow of crude oil, which is 2.2 and 1.2 times higher than that of the precision mesh and pre-filled screen, respectively. These research results can provide technical support and theoretical guidance for the sustained, efficient, and stable production of sand reservoirs in the Bohai Oilfield. Full article

Oxygen-reduced air injection technology has demonstrated considerable potential for developing heavy oil reservoirs. However, the low-temperature oxidation (LTO) behavior and non-isothermal heat release of heavy oil under oxygen-reduced conditions remain poorly understood. Accordingly, this study systematically investigated the oxygen consumption characteristics of heavy crude oil under two oxygen concentrations (8% and 10%) through isothermal static oxidation experiments. Additionally, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were employed to analyze the microstructural evolution of rock cuttings and the exothermic characteristics of heavy oil before and after oxidation. The results indicated that as the oxygen concentration increased from 8% to 10%, the pressure drop during the LTO process rose from 1.73 to 2.04 MPa, and the oxygen consumption rate increased from 1.47 × 10⁻⁵ to 2.06 × 10⁻⁵ mol/(h·mL). This demonstrated that higher oxygen partial pressure promoted LTO reactions, thereby generating more abundant coke precursors for the subsequent high-temperature oxidation (HTO) stage. SEM analysis revealed that the microstructure of the rock cuttings after oxidation transitioned from an originally smooth, “acicular” morphology to a “flaky” structure characterized by extensive crack development, which significantly improved the connectivity of the pore-fracture system. DSC analysis further demonstrated that the mineral components in the rock cuttings played a dual role during the oxidation process: at the LTO stage, their heat capacity effect suppressed the exothermic behavior during oxidation; whereas at the HTO stage, their larger specific surface area and the catalytic effect of clay minerals enhanced the heat release from coke combustion. This study thus provided a theoretical foundation for developing heavy oil reservoirs through oxygen-reduced air injection. Full article

Energy security crises have historically been turning points for energy systems, exposing vulnerabilities, reshaping policy priorities, and boosting technological change. However, whether—and to what extent—such crises accelerate low-carbon transitions remains contested. This paper examines the effects of the 2022 energy crisis on the European Union (EU)’s energy transition, using policy analysis combined with a quantitative assessment of renewable energy trends, forecasts, and targets. We analyse the ambition, implementation, and outcomes of the REPowerEU plan, the main response to the crisis. In an unprecedented move, REPowerEU securitised renewable energy as a means to reduce dependence on Russian energy imports. However, the plan only moderately increased earlier renewable energy targets and did not reverse declining subsidies despite more forceful implementation measures. Its effects have been uneven across technologies. Already accelerating solar may overshoot its targets, onshore wind might only slightly accelerate beyond its current steady growth, and offshore wind remains constrained by economic and institutional uncertainties. Despite increased subsidies for fossil fuels, coal continued declining, oil remained stable, and natural gas dropped. Overall, REPowerEU sustained rather than transformed the EU’s low-carbon transition, illustrating both the potential and limits of accelerating decarbonisation under security crises. Full article

CO₂ miscible flooding provides dual advantages in enhancing oil recovery and facilitating geological sequestration, and has become a key technical approach for developing low-permeability oil reservoirs and carbon emission reduction. The pore-scale flow mechanisms governing CO₂ behavior during miscible flooding are crucial for achieving efficient oil recovery and secure geological storage of CO₂. In this study, pore-scale two-phase flow simulations of CO₂ miscible flooding in porous media are performed using a coupled laminar-flow and diluted-species-transport framework. The model captures the effects of diffusion, concentration distribution, and pore structure on the behavior of CO₂ miscible displacement. The results indicate that: (1) during miscible flooding, CO₂ preferentially displaces oil in larger pore throats and subsequently invades smaller throats, significantly improving the mobilization of oil trapped in small pores; (2) increasing the injection velocity accelerates the displacement front and improves oil utilization in dead-end and trailing regions, but a “velocity saturation effect” is observed—when the inject velocity exceeds 0.02 m/s, the displacement pattern stabilizes and further gains in ultimate recovery become limited; (3) higher injected CO₂ concentration accelerates CO₂ accumulation within the pores, enlarges the miscible sweep area, promotes a more uniform concentration field, leads to a smoother displacement front, and reduces high-gradient regions, thereby suppressing local instabilities, and improves displacement efficiency, although its effect on overall recovery remains modest; (4) CO₂ dynamic viscosity strongly influences flow stability: low-viscosity conditions promote viscous fingering and severe local bypassing, whereas higher viscosity stabilizes flow but increases injection pressure drop and energy consumption, indicating a necessary trade-off between flow stability and operational efficiency. Full article

At the moment, there are no available data or studies exploring the production of naphtha boiling range hydrocarbons via hydroprocessing of pretreated residual lipids. To that aim, this study targets the production of naphtha, jet and diesel boiling range hydrocarbons via hydroprocessing of refined waste cooking oils utilizing solar hydrogen. The technology was first optimized in a TRL-3 plant. A heteroatom removal catalyst and a saturation catalyst were combined with an isomerization and hydrocracking catalyst to upgrade lipids. The results show that the severity of the process plays an important role in the yields of the fuels. Higher naphtha yields were observed at 663 K, 13.78 MPa and a liquid hourly space velocity of 0.33 h⁻¹, leading to the production of a fuel consisting of 34 wt% naphtha, 23 wt% jet and 42 wt% diesel boiling range hydrocarbons. Subsequently, the technology was validated and demonstrated in an industrially relevant unit (TRL-5). The results from the fuel characterization show that the diesel fraction can be used as a high-quality road transport drop-in fuel, as it is characterized by a high cetane index (~96) and a high flash point (414 K). Although jet and naphtha meet most commercial fuel specifications, further optimization of the process is necessary to meet fuel standards. In conclusion, the current work provides novel data relevant to industrial applications for road, aviation and maritime fuel production via hydroprocessing of refined waste cooking oil. Full article

We present a theoretical framework describing how the electrophoretic mobility of a weakly charged oil droplet in an aqueous electrolyte varies with frequency when the system is subjected to an oscillatory electric field. The surface charge of the droplet arises from the adsorption of electrolyte ions. Our analysis is based on a simplified form of the Baygents–Saville model, in which the interior of the droplet is assumed to contain no dissolved ions. In this approach, variations in interfacial tensions along the droplet surface, generated by the Marangoni effect, are explicitly included. From the formulation, we derive a general expression for the dynamic electrophoretic mobility of a charged spherical droplet, and, in addition, obtain concise analytical formulas applicable in the limit of small zeta potentials. Full article