Oil Viscosity Research Articles

Study on fluid phase behavior characteristics of low permeability reservoir under different CO2 injection amounts

M reservoir is a low peremeability reservoir located in northwest China. Currently, it faces the problem of difficult water injection, low single well production, and rapid production decline. CO2 flooding technology is considered to be implemented to solve these problems by effectively supplementing formation energy. Considering that the phase behavior of reservoir fluid during CO2 injection and its influence on the development effect are complex, the PVT test experiment of reservoir fluid is carried out to analyze the variation of reservoir fluid properties under different CO2 injection volumes. The experimental results show that the saturation pressure, solution gas-oil ratio, volume coefficient and expansion coefficient of crude oil increase with the increase of CO2 injection, while the viscosity and density of oil continue to decrease. When the CO2 injection amount reaches 32 %, the dissolved gas-oil ratio increases from the original 36.2 m³/m³to 150.2 m³/m³, the viscosity of the formation oil is reduced by about 76 % than before CO2 injection; and the volume of crude oil has expanded to 1.28 times of that without CO2 injection. Moreover, the P-T phase diagram is drawn and the influence of CO2 injection on the distribution of phase regions in the phase diagram and the critical parameters of oil is analyzed. The high pressure physical properties of reservoir fluids at different CO2 injection volumes are obtained, which can provide a good foundation for the study of enhancing oil recovery by CO2 injection in M reservoir.

Impact of CuO nanoparticles on the viscosity and vibration damping characteristics of shock absorber oil

This study investigates the potential of copper oxide (CuO) nanoparticles as additives to enhance the viscosity and vibration-damping characteristics of shock absorber oil. Shock absorbers play a critical role in vehicle safety and handling by mitigating vibrations from road irregularities. However, their effectiveness deteriorates over time. To address this, CuO nanoparticles were explored for their ability to improve lubricant performance. Nano-lubricants were prepared by dispersing CuO nanoparticles at varying concentrations of 0.25 wt%, 0.5 wt%, 1 wt%, and 1.5 wt% in a base oil using ultrasonication. The novelty of this research lies in the innovative use of CuO nanoparticles to significantly enhance the viscosity and vibration-damping properties of shock absorber oil. The viscosity of these nano-lubricants increased significantly, with the 1 wt% CuO nano-lubricant achieving a 20% increase at 25 °C compared to the base oil, indicating improved load-carrying capacity and potential friction reduction. Vibration damping performance was evaluated using a dedicated shock absorber test rig. The nano-lubricants exhibited reduced overall vibration acceleration compared to plain oil, with a 15% improvement in damping effectiveness at the optimal CuO concentration. However, the transmissibility ratio, a key damping metric, did not show significant variation, suggesting that traditional shock absorber designs might require modifications to fully leverage the benefits of CuO nanoparticles. These findings demonstrate the potential of CuO nanoparticles to enhance the viscosity and damping characteristics of shock absorber oil, leading to improved performance at lower temperatures.

Experimental study on in-situ emulsification of heavy oil in porous media

Under the strategic goal of “dual-carbon”, reducing oil viscosity by in-situ emulsification using chemical method has become a new direction for high-efficiency and low-carbon development of heavy oil reservoirs. This technology can transform the originally immovable heavy oil into movable dispersed oil droplets through in-situ emulsification, and thus enhances heavy oil recovery. However, there is still a lack of sufficient understanding about the characteristics and influencing laws of in-situ emulsification of heavy oil in porous media. So, this paper carried out experimental studies on in-situ emulsification and influencing factors for heavy oil in porous media. The results show that, due to the transport and adsorption loss of viscosity reducer in porous media, the emulsification area expands gradually from the inlet to the outlet. At the same sampling position, with the increase of injection volume, the dispersed oil droplet size decreases, the distribution density increases, and the color of produced liquid changes from light yellow to dark brown. Under the same injection volume, the closer to the outlet, the smaller the particle size of the dispersed oil droplets and the higher the distribution density, which is resulted from the shearing effect of the porous media. With the increase of injection rate, the hydrodynamic shear effect is enhanced, so the in-situ emulsification of heavy oil starts earlier and the emulsification oil ratio curves have a higher slope and distribute more densely. With the increase of agent concentration, the adsorbed number of viscosity reducer molecules on the oil–water interface is increased, making it easier to emulsify the remaining oil. With the increase of pre-conversion oil recovery, the remaining oil in the porous media is more dispersed and the oil–water contact surface increases, so the emulsification is easier and the percentage of dispersed oil droplets in the produced oil phase increases. The research results based on sampling analysis deepen our understanding on in-situ emulsification of heavy oil in porous media, which provides valuable reference for designing suitable viscosity reducer agent and effectively enhancing heavy oil recovery in the future.

Machine Learning Analysis Using the Black Oil Model and Parallel Algorithms in Oil Recovery Forecasting

The accurate forecasting of oil recovery factors is crucial for the effective management and optimization of oil production processes. This study explores the application of machine learning methods, specifically focusing on parallel algorithms, to enhance traditional reservoir simulation frameworks using black oil models. This research involves four main steps: collecting a synthetic dataset, preprocessing it, modeling and predicting the oil recovery factors with various machine learning techniques, and evaluating the model’s performance. The analysis was carried out on a synthetic dataset containing parameters such as porosity, pressure, and the viscosity of oil and gas. By utilizing parallel computing, particularly GPUs, this study demonstrates significant improvements in processing efficiency and prediction accuracy. While maintaining the value of the R2 metric in the range of 0.97, using data parallelism sped up the learning process by, at best, 10.54 times. Neural network training was accelerated almost 8 times when running on a GPU. These findings underscore the potential of parallel machine learning algorithms to revolutionize the decision-making processes in reservoir management, offering faster and more precise predictive tools. This work not only contributes to computational sciences and reservoir engineering but also opens new avenues for the integration of advanced machine learning and parallel computing methods in optimizing oil recovery.

Synthesis and Mechanistic Investigation of an Amphiphilic Polymer in Enhancing Extra-Heavy Oil Recovery via Viscosity Reduction.

When applied to extra-heavy oil, conventional polymer surfactants exhibit poor efficacy in reducing viscosity and have limited adaptability. In this work, a novel amphiphilic polymer named PAADB was prepared by incorporating 2-acryloylamino-2-methyl-1-propanesulfonic acid (AMPS), benzyldimethyl [2-[(1-oxoallyl) zoxy] propyl] ammonium chloride (DML), and poly(ethylene glycol) methyl ether acrylate (BEM) into the main chain of acrylamide through free radical polymerization. PAADB exhibited outstanding interfacial activity, water-phase thickening ability, and emulsifying performance. The critical micelle concentration of PAADB was approximately 2500 mg/L, with a viscosity of 84.69 mPa·s at 50 °C. Additionally, interfacial tension experienced a notable decrease from 46.53 to 14.56 mN/m. At an optimal concentration of 4000 mg/L, PAADB reduced the viscosity of extra-heavy oil by over 92% across various temperatures and by more than 93% for different types of extra-heavy oil. PAADB demonstrated excellent emulsification ability and emulsion stability, effectively dispersing crude oil to create water-in-oil droplets measuring 35.33 μm in size. Meanwhile, molecular dynamics simulations further unveiled the viscosity reduction mechanism of PAADB. The hydrophilic groups within PAADB molecules are regularly distributed on the water interface, while the hydrophobic groups infiltrate the oil molecules to form a stable interfacial film. PAADB and asphaltene spontaneously form a sandwich structure, reducing intermolecular forces and disrupting the interlayer structure of asphaltene molecules. In general, this novel amphiphilic polymer demonstrates broad applicability and potential in extra-heavy oil recovery, providing valuable insights for the development of new heavy oil viscosity reducers (HOVRs).

Synergistic Catalysis of Water-Soluble Exogenous Catalysts and Reservoir Minerals during the Aquathermolysis of Heavy Oil.

Oil serves as the essential fuel and economic foundation of contemporary industry. However, the use of traditional light crude oil has exceeded its supply, making it challenging to meet the energy needs of humanity. Consequently, the extraction of heavy oil has become crucial in addressing this demand. This research focuses on the synthesis of several water-soluble catalysts that can work along with reservoir minerals to catalyze the hydrothermal cracking process of heavy oil. The goal is to effectively reduce the viscosity of heavy oil and lower the cost of its extraction. Based on the experimental findings, it was observed that when oil sample 1 underwent hydrothermal cracking at a temperature of 180 °C for a duration of 4 h, the amount of water added and catalyst used were 30% and 0.2% of the oil sample dosage, respectively. It was further discovered that the synthesized Mn(II)C was able to reduce the viscosity of oil sample 1 by 50.38%. The investigation revealed that the combination of Mn(II)C + K exhibited a significant synergistic catalytic impact on reducing viscosity. Initially, the viscosity reduction rate was 50.38%, which climbed to 61.02%. Subsequently, when catalyzed by the hydrogen supply agent isopropanol, the rate of viscosity reduction rose further to 91.22%. Several methods, such as freezing point analysis, thermogravimetric analysis, DSC analysis, component analysis, gas chromatography, wax crystal morphology analysis, and GC-MS analysis, were conducted on aqueous organic matter derived from heavy oil after undergoing different reaction systems. These analyses confirmed that the viscosity of the heavy oil was decreased. By studying the reaction mechanism of the model compound and analyzing the aqueous phase, the reaction largely involves depolymerization between macromolecules, breakdown of heteroatom chains, hydrogenation, ring opening, and other related consequences. These actions diminish the strength of the van der Waals force and hydrogen bond in the recombinant interval, impede the creation of a grid-like structure in heavy oil, and efficiently decrease its viscosity.

A Scalable and Surfactant-Free Emulsion Method for Producing Microbeads from Varied Biomass Feedstocks.

Despite national and international regulations, plastic microbeads are still widely used in personal care and consumer products (PCCPs). These exfoliants and rheological modifiers cause significant microplastic pollution in natural aquatic environments. Microbeads from nonderivatized biomass like cellulose and lignin can offer a sustainable alternative to these nondegradable microplastics, but processing this biomass into microbeads is challenging due to limited viable solvents and high biomass solution viscosities. To produce biomass microbeads of the appropriate size range for PCCPs (ca. 200-800 μm diameter) with shapes and mechanical properties comparable to those of commercial plastic microbeads, we used a surfactant-free emulsion/precipitation method, mixing biomass solutions in 1-ethyl-3-methylimidazolium acetate (EMImAc) with various oils and precipitating with ethanol. While yield of microbeads within the target size range highly depends on purification conditions, optimized protocols led to >90% yield of cellulose microbeads. Kraft lignin was then successfully incorporated into beads at up to 20 wt %; however, higher lignin contents result in emulsion destabilization unless surfactant is added. Finally, the microbead shape and surface morphology can be tuned using oils of varying viscosities and interfacial tensions. Dripping measurements and pendant drop tensiometry confirmed that the higher affinity of cellulose for certain oil/IL interfaces largely controlled the observed surface morphology. This work thus outlines how biomass composition, oil viscosity, and interfacial properties can be altered to produce more sustainable microbeads for use in PCCPs, which have desirable mechanical properties and can be produced over a wide range of shapes and surface morphologies.

Analysis of Inter-Layer Interference in Multi-Layer Reservoir Commingled Production Wells

During the operation of commingled production wells, inter-layer interference is a key factor affecting the recovery rate and flooding extraction efficiency. This study proposes a well deliverability equation that is characterized by a multi-parameter coupled inter-layer interference coefficient, which is applied to quantify the commingled production wells in a multi-layer reservoir. This study used principal component analysis (PCA) to study the combined effects of correlation parameters for inter-layer interference. The results show that the starting pressure gradient and the crude oil viscosity contrast have the most significant impact on inter-layer interference. Changes in these two parameters directly enhance the heterogeneity between different oil layers, thereby intensifying inter-layer interference. Additionally, the positive correlation between permeability and permeability contrast also highlights the contribution of physical property differences in the oil layers to the interference. The sensitivity analysis shows the main influencing factors of inter-layer interference in commingled production wells. providing references for subsequent improvements and optimization of the exploitation schemes and adjustments in reservoir management measures. The results not only enhance the understanding of the mechanisms of inter-layer interference in the exploitation of multi-layer oil reservoirs but also provide scientific evidence and technical support for oilfield development.

Effect of Grease Composition on Impact-Sliding Wear

Impact-sliding experiments were performed by using four self-made lithium-based greases, namely Yangtze Grease 1, Yangtze Grease 2, Yangtze Grease 3, and Yangtze Grease 4. The influence of base oil viscosity, thickener content, and morphology of thickener fiber clusters on the lubricating state were visually explored, combined with field-emission microscopy and two-light interference technology. The grease film distribution at the middle section was measured using Dichromatic Interference Intensity Modulation (DIIM) software. All experiments were executed in a completely flooded environment. The results show that among the components of grease, the base oil’s viscosity has the greatest impact on the anti-wear performance of the grease. As the viscosity of the base oil increases, the grease exhibits better anti-wear performance. The grease film thickness under the condition of high-viscosity base oil is about 10 times higher than that under the condition of low-viscosity base oil. Secondly, the content of thickener in the grease needs to be controlled within a reasonable range. The experiments indicate that the effect of thickener content on the grease’s film-forming properties becomes more pronounced at higher speeds. From the experiment using YG 4, it can be seen that a higher thickener content under high-speed conditions increases the thickness of the lubricating grease film by about 10 times. The dimensions of the thickener fibers and the density of their entanglement structure significantly influence the rheological properties and load-bearing capacity of the grease. Larger fiber sizes and higher entanglement densities result in reduced grease fluidity and recovery but enhance its load-bearing capabilities. In order to obtain the best anti-wear performance during impact-sliding motion, the size of the thickener fiber and the density of the entanglement structure need to be controlled within an appropriate range.

Pore-scale investigation of injectivity impairment caused by oil droplets during produced water reinjection using volume of fluid method

Produced water from subsurface may often contain oil droplets, even when not directly extracted from oil wells. Oil droplets can migrate into water-bearing stratigraphic layers, leading to the generation of oily water. This study evaluates the dynamic clogging behavior of oil droplets concerning various injection fluid properties, including injection velocity, interfacial tension, oil droplet size, concentration, viscosity, and medium wettability. The primary objective is to validate common clogging mechanisms associated with oil droplets and quantitatively assess the impact of these parameters on injectivity impairment within porous media. To achieve this, a volume of fluid approach is employed, integrating fluid interfacial properties to account for coalescence and surface adherence. The results are then compared to similar findings in existing literature. Our study reveals that increasing the capillary number enhances injectivity, up to a critical point where the flow regime attains optimal stability, contingent upon relative permeability and phase mobility. Investigation into system wettability demonstrates that while contact angle significantly affects the injectivity index, the impact on injectivity diminishes when altering it beyond 90°. Aligning droplet viscosity with that of the displacing fluid proves to be an effective solution for minimizing injectivity impairment, nearly eliminating damage. This research provides valuable insights into commonly studied emulsion parameters, like Jamin Ratio and oil concentration, and underlines the importance of investigating less-explored factors, such as wettability and oil viscosity, particularly in scenarios involving unstabilized droplets and coalescence dynamics.

Impact of Oil Viscosity on Emissions and Fuel Efficiency at High Altitudes: A Response Surface Methodology Analysis

This study investigates the effect of oil viscosity on pollutant emissions and fuel consumption of an internal combustion engine (ICE) at high altitudes using a response surface methodology (RSM). A Chevrolet Corsa Evolution 1.5 SOHC gasoline engine was used in Cuenca, Ecuador (2560 m above sea level), testing three lubricating oils with kinematic viscosities of 9.66, 14.08, and 18.5 mm2/s, measured at a temperature of 100 °C under various engine speeds and loads. Key findings include the following: hydrocarbon (HC) emissions were minimized from 150.22 ppm at the maximum load to 7.25 ppm with low viscosity and load; carbon dioxide (CO2) emissions peaked at 15.2% vol with high viscosity and load; carbon monoxide (CO) ranged from 0.04% to 3.74% depending on viscosity and load; nitrogen oxides (NOx) were significantly influenced by viscosity, RPM, and load, indicating a need for model refinement; and fuel consumption was significantly affected by load and viscosity. RSM-based optimization identified optimal operational conditions with a viscosity of 13 mm2/s, 1473 rpm, and a load of 78%, resulting in 52.35 ppm of HC, 13.97% vol of CO2, 1.2% vol of CO, 0 ppm of NOx, and a fuel consumption of 6.66 L/h. These conditions demonstrate the ability to adjust operational variables to maximize fuel efficiency and minimize emissions. This study underscores the critical role of optimizing lubricant viscosity and operational conditions to mitigate environmental impact and enhance engine performance in high-altitude environments.

Photothermally responsive, magnetic and flame-retardant MOF-based polyurethane sponges for oil/water separation and emulsion purification

The development of a multifunctional sponge with photothermal effect for adsorbing high-viscosity oil, as well as magnetic drive and excellent flame-retardant property, is significant in the field of oil/water separation, but also extremely challenging. In this work, a multifunctional MOF-based polyurethane (PU) sponge was successfully prepared using a simple method. Fe3O4-loaded NH2-MIL-101(Fe) nanoparticles were immobilized on PU sponge via low surface energy polydimethylsiloxane (PDMS) to obtain superhydrophobic NH2-MIL-101(Fe)@Fe3O4@PDMS@PU sponge (WCA = 155.6°), which exhibited excellent oil absorption, oil/water selectivity and reusability. The introduction of NH2-MIL-101(Fe)@Fe3O4 endowed the modified sponge with excellent photothermal properties, which was manifested in that with the help of solar energy, the sponge heated up rapidly and could achieve efficient adsorption of high viscosity oil. The magnetic property of the modified sponge made it effectively separate oil and water mixture along a certain path under the control of a magnetic field. In addition, the NH2-MIL-101(Fe)@Fe3O4@PDMS coating made the sponge exhibit excellent flame retardancy, which could effectively improve the safety of the modified PU sponge in practical applications. In summary, NH2-MIL-101(Fe)@Fe3O4@PDMS@PU sponge has potential application prospects in the oil/water separation field.

A solar-driven nanocellulose Janus aerogel with excellent floating stability and dual functions of oil–water separation and photocatalytic degradation of organic pollutants

Effective and practical cleanup of viscous crude oil spills is extremely important in real harsh marine environments. Herein, we designed a solar–driven, nanocellulose-based Janus aerogel (Janus-A) with excellent floating stability and dual function of oil–water separation and degradation of aqueous organic pollutants. Janus-A, with its amphiprotic nature, was prepared through polypyrrole (PPy) deposition, freeze-drying, octyltrichlorosilane (OTS) impregnation, TiO2 spraying on the bottom surface, and UV irradiation treatment. The photothermal conversion effect of PPy coating raised the surface temperature of aerogel to 75.8 °C within 6 min under one simulated solar irradiation, which greatly reduced the viscosity of the crude oil and increased the absorption capacity of the aerogel to 36.7 g/g. Benefiting from the balance between the buoyancy generated by the hydrophobic part and water absorption of the hydrophilic part, Janus-A showed excellent floating stability under simulated winds and waves. In addition, Janus-A exhibited high degradation efficiency for organic pollutants in water owing to the synergistic photocatalytic properties of TiO2 and PPy. These excellent performances make Janus-A ideal for integrated water–oil separation and water remediation.

“Component flow” conditions and its effects on enhancing production of continental medium-to-high maturity shale oil

Based on the production curves, changes in hydrocarbon composition and quantities over time, and production systems from key trial production wells in lacustrine shale oil areas in China, fine fraction cutting experiments and molecular dynamics numerical simulations were conducted to investigate the effects of changes in shale oil composition on macroscopic fluidity. The concept of “component flow” for shale oil was proposed, and the formation mechanism and conditions of component flow were discussed. The research reveals findings in four aspects. First, a miscible state of light, medium and heavy hydrocarbons form within micropores/nanopores of underground shale according to similarity and intermiscibility principles, which make components with poor fluidity suspended as molecular aggregates in light and medium hydrocarbon solvents, such as heavy hydrocarbons, thereby decreasing shale oil viscosity and enhancing fluidity and outflows. Second, small-molecule aromatic hydrocarbons act as carriers for component flow, and the higher the content of gaseous and light hydrocarbons, the more conducive it is to inhibit the formation of larger aggregates of heavy components such as resin and asphalt, thus increasing their plastic deformation ability and bringing about better component flow efficiency. Third, higher formation temperatures reduce the viscosity of heavy hydrocarbon components, such as wax, thereby improving their fluidity. Fourth, preservation conditions, formation energy, and production system play important roles in controlling the content of light hydrocarbon components, outflow rate, and forming stable “component flow”, which are crucial factors for the optimal compatibility and maximum flow rate of multi-component hydrocarbons in shale oil. The component flow of underground shale oil is significant for improving single-well production and the cumulative ultimate recovery of shale oil.

Wear Performance Evaluation of Polymer Overlays on Engine Bearings.

Modern engine bearing materials encounter the challenge of functioning under conditions of mixed lubrication, low viscosity oils, downsizing, start-stop engines, potentially leading to metal-to-metal contact and, subsequently, premature bearing failure. In this work, two types of polymer overlays were applied to the bearing surface to compensate for extreme conditions, such as excessive loads and mixed lubrication. Two different polymer overlays, created through a curing process on a conventional engine bearing surface with an approximate thickness of 13 µm, were investigated for their friction and wear resistances under a 30 N load using a pin-on-disc setup. The results indicate that the newly developed polymer overlay (NDP, PAI-based coating) surface has a coefficient of friction (COF) of 0.155 and a wear volume loss of 0.010 cm3. In contrast, the currently used polymer overlay (CPO) in this field shows higher values with a COF of 0.378 and a wear volume loss of 0.024 cm3, which is significantly greater than that of the NDP. It was found that, in addition to accurately selecting the ratios of solid lubricants, polymer resins, and wear-resistant hard particle additives (metal powders, metal oxides, carbides, etc.) within the polymer coating, the effective presence of a transfer film providing low friction on the counter surface also played a crucial role.

Fe3O4/AM-PAA/Ni nanomagnetic spheres: A breakthrough in in-situ catalytic reduction of heavy oil viscosity

In-situ catalytic technology for heavy oil reservoirs is widely regarded as one of the most promising methods for heavy oil extraction. However, its large-scale application faces significant challenges due to the lack of efficient stable catalysts, and issues related to the dispersion of catalysts during the injection process. This study introduces a modified nanomagnetic sphere, Fe3O4/AM-PAA/Ni, with catalytic and surface-active properties. With a 1 % mass fraction of Fe3O4/AM-PAA/Ni and 1 % tetrahydronaphthalene (hydrogen donor) at 180°C, heavy oil viscosity dropped by 94.21 %, and asphaltenes and resin reduced by approximately 20 %. Core flooding and alternating magnetic field experiments demonstrated superior dispersion and heating effects for Fe3O4/AM-PAA/Ni nanoparticles compared to traditional Fe3O4. Mechanism analysis revealed that the unpaired electrons and d-orbitals on Fe3O4/AM-PAA/Ni’s transition metals facilitated hydrocarbon chain breakdown and interaction with heteroatoms, while nanoscale nickel enhanced catalytic activity for C-S bond cleavage, further reducing oil viscosity. The amphiphilic polymers on the surface of magnetic nanospheres significantly enhanced the dispersion of the catalyst in heavy oil, increasing the reaction contact area and thereby improving the catalytic performance. This research not only offers vital theoretical insights and practical strategies for efficient heavy oil extraction but also paves the way for advancements in reservoir in-situ modification technologies, showcasing significant application potential and academic value.

Experimental and Numerical Simulation Study on CO2-Assisted Steamflooding in Ultraheavy Oil Reservoirs

Summary Certain ultraheavy oil reservoirs with depths approaching 1000 m feature wide well spacing. After cyclic steam stimulation (CSS), cold oil zones with high residual oil saturation exist between wells. This leads to a high oil saturation at the steam front during the subsequent steamflooding process, which in turn results in a high injection pressure. The simultaneous injection of CO2 and steam into the formation can optimize formation pressure and enhance steam utilization efficiency. A majority of laboratory-based experimental studies have reported favorable outcomes with CO2-assisted steamflooding. However, some field tests of CO2-assisted steamflooding have encountered severe steam channeling problems, resulting in oil recovery and an oil/steam ratio below the expected level. Consequently, this study uses an ultraheavy oil reservoir as a case study and integrates physical simulation with numerical simulation to investigate the impact of CO2-assisted steamflooding on enhanced oil recovery in ultraheavy oil reservoirs. The findings suggest that the beneficial effect of CO2 in reducing oil viscosity and injection pressure plays a significant role in models with smaller thickness, thereby improving oil production rate and recovery factor. However, as the thickness of the model increases, the adverse effect of CO2 exacerbating steam channeling becomes increasingly evident, leading to a decline in the oil recovery factor and a longer duration to reach the maximum recovery factor. Therefore, in field applications, it is essential to consider adjusting the CO2 injection method or using thermosetting plugging agents to achieve superior results.

Innovative strategy for the facile construction of active multifunctional coating on inert thermal insulation surface

Ethylene propylene diene monomer rubber is highly attractive as a thermal insulation material for solid rocket motors but is plagued by its inherent low wettability. Existing methods have been used to solve this problem by manually or mechanically sanding the surface, which is environmentally hazardous. Herein, a multifunctional composite coating is constructed on the surface of inert thermal insulation materials using a two-step low temperature plasma surface treatment via an efficient hydrogen-bonding assembly strategy. The resultant composite coating exhibits excellent adhesion to the inert thermal insulation substrate. Benefitting from this, the coating retained its superhydrophilicity after 80 abrasion cycles and 12 h of agitation scrubbing with saturated salt water. Due to the superhydrophilicity of the coating, a self-cleaning effect for oils of different viscosities on the surface can be achieved by the simple action of water. Besides the adiabatic performance tests showed that the average top surface temperature of the coated thermal insulation was 30.9 °C lower than that of the original thermal insulation. Char residue analysis showed that the coating formed a more complete char layer at high temperatures, resulting in improved adiabatic performance. Our work would afford a new frontier to fabricate solid rocket motor thermal insulation materials with excellent surface comprehensive properties in a simple, eco-friendly and sustainable way, opening new possibilities for the advancement of high-performance inert materials.

Improved Amott Method to Determine Oil Recovery Dynamics from Water-Wet Limestone Using GEV Statistics

Counter-current spontaneous imbibition of water is a critical oil recovery mechanism. In the laboratory, the Amott test is a commonly used method to assess the efficacy of brine imbibition into oil-saturated core plugs. The classic Amott-cell experiment estimates ultimate oil recovery, but not the recovery dynamics that hold fundamental information about the imbibition mechanisms. Retention of oil droplets at the outer core surface and initial production delay are the two key artifacts of the classic Amott experiment. This retention, referred to here as the “external-surface oil holdup effect” or simply “oil holdup effect”, often results in stepwise recovery curves that obscure the true dynamics of spontaneous imbibition. To address these holdup drawbacks of the classic Amott method, we modified the Amott cell and experimental procedure. For the first time, using water-wet Indiana limestone cores saturated with brine and mineral oil, we showed that our improvements of the Amott method enabled accurate and reproducible measurements of oil recovery dynamics. Also for the first time, we used the generalized extreme value (GEV) statistics to describe oil production histories from water-wet heterogeneous limestone cores with finite initial water saturations. We demonstrated that our four-parameter GEV model accurately described the recovery dynamics, and that optimal GEV parameter values systematically reflected the key characteristics of the oil–rock system, such as oil viscosity and rock permeability. These findings gave us a more fundamental understanding of spontaneous, counter-current imbibition mechanisms and insights into what constitutes a predictive model of counter-current water imbibition into oil-saturated rocks with finite initial water saturation.

Analyzing the influence of feedstock selection in pyrolysis on aviation gas turbine engines: A study on performance, combustion efficiency, and emission profiles

Commercial aviation is primarily reliant on fossil fuels, yet the depletion of these sources and the consequences of climate change necessitates the exploration of sustainable alternatives. The pyrolysis process offers a viable method for producing biofuels from various feedstocks. This research examines the combustion, emission, and performance characteristics of biofuels derived from agricultural residues, waste tyres, and plastics using pyrolysis. Pyrolysis oils derived from forestry or agricultural products exhibit high viscosity and moisture content, which impairs combustion efficiency and increases carbon monoxide (CO) from 70 % to 187 % and unburned hydrocarbon (UHC) emissions. Conversely, pyrolysis oils from plastics and waste tyres provide stable combustion with carbon monoxide and total hydrocarbon emissions (THC) comparable to those of commercial jet fuel. However, nitrogen oxide (NOX) emissions are significantly elevated from 57 % to 157 %. Engine performance tests demonstrated that forestry pyrolysis oils result in thrust loss due to their high viscosity value (14.3–113 mm2/s) and low calorific value (17.3–31.7 MJ/kg). In contrast, plastic and tyre pyrolysis oil perform similarly to commercial jet fuels but may potentially cause performance loss due to their high aromatic content (>47.67 %). Overall, upgrading the viscosity, moisture, and aromatic content of pyrolysis oils can enhance their suitability as alternative aviation fuels. These improvements could assist the aviation sector in achieving its carbon-neutral goals by making pyrolysis oils competitive with conventional jet fuels.