Search Results (305)

In this paper, to remove the water lock effect in tight gas reservoirs, amphipathic polymer-modified titanium quantum dots (PTQs) were synthesized via in situ polymerization, showing a hyper-branched structure and an excellent synergistic effect with the nonionic fluorocarbon surfactant to break the water lock. The molecular structure, fluorescent property, and micromorphology of the PTQs were obtained. The surface activity and wettability alteration of rock are discussed. Results show that PTQs have zwitterionic hydrophilic groups and the hydrophobic structure of long-chain groups on their molecular structure. PTQ fluid, with a median particle size of 3.6 nm, showed strong green fluorescence and had excellent dispersibility in 50,000 mg/L of standard saline fluid at 120 °C. Additionally, the surface tension decreased to 18.6 mN/m at a PTQ concentration of 0.08%. At a 0.1% concentration, PTQ fluid altered the water wettability of tight sandstone to 67.2°, which resulted in lower capillary resistance. Furthermore, the surfactant (PHPE) had a good synergistic effect with the PTQs to decrease surface tension and alter the wettability of the sandstone surface, leading to lower surface tension and significant amphiphobicity. The strong surface activity of PTQs results from their specific molecular structure, which enables electrostatic attraction, quantum size effects, hydrogen bonding, and van der Waals forces between the inter-polar molecules of PTQs and the surface of sandstone to forcefully eliminate the water lock effect. This study offers key guidance for the development of a high-performance water-lock-breaking agent and application of titanium quantum dots in tight gas reservoirs. Full article

This study addresses several key limitations identified in previous research on additively manufactured PLA composites. Unlike most earlier studies that focused primarily on the characterization of as-printed materials, the present work systematically investigates both mechanical and surface behavior before, during, and after artificial aging. In addition, six different printing configurations and reinforcement types (PVC and fiberglass mesh) were analyzed under controlled conditions, enabling a more reliable assessment of their combined influence on composite performance. Printed specimens were artificially aged for 45 and 90 days. The aging protocol combined cyclic changes in moisture, temperature, UV, and IR agents, trying to mimic real exploitation conditions as realistically as possible. The chemical and surface changes during aging were tracked using FTIR spectroscopy, colorimetry, contact angle, and surface free energy measurements. Mechanical performance at 0, 45, and 90 days was evaluated through tensile, three-point bending, and Charpy impact tests, as well as full-scale cantilever loading tests of real printed drone arms. Results show that artificial aging causes measurable chemical and surface modifications, as indicated by changes in the FTIR degradation index and surface wettability. However, these changes do not result in severe mechanical degradation within the investigated aging period. Reinforcement in the form of incorporated PVC and fiberglass mesh significantly affected failure behavior. Specimens printed with higher infill density and thicker infill lines generally exhibit improved mechanical properties. Specimens stiffness and impact resistance were also altered. Results demonstrate that reinforced PLA structures are suitable for lightweight drone applications. Full article

Heavy oil and extra-heavy oil represent mobility-limited petroleum resources because supramolecular associations of asphaltenes and resins, together with strong interfacial resistance, generate extremely high apparent viscosity. In recent years, nanotechnology has emerged as a promising approach for viscosity management and enhanced oil recovery (EOR). This review critically examines recent advances in nano-assisted viscosity reduction from a reservoir-operational perspective and organizes the literature into two field-relevant categories: metal-based and non-metal nano-systems. Metal-based nanoparticles (NPs) mainly promote catalytic aquathermolysis and related bond-cleavage and hydrogen-transfer reactions under hydrothermal conditions, enabling partial upgrading and persistent viscosity reduction during thermal recovery. In contrast, non-metal nano-systems—particularly silica- and graphene-oxide-derived materials—primarily operate through interfacial and structural regulation mechanisms at low or moderate temperatures. These effects include wettability alteration, interfacial-film stabilization, modification of asphaltene aggregation behavior, and the formation of dispersed-flow regimes such as Pickering-type emulsions that reduce apparent flow resistance in multiphase systems. Beyond summarizing nanomaterial types, this review emphasizes reservoir-scale considerations governing field applicability, including brine stability, NPs transport and retention in porous media, and formulation compatibility. Comparative analysis highlights the distinct operational windows of thermal catalytic nano-systems and cold-production nano-systems, providing a reservoir-oriented framework for designing nano-assisted viscosity-reduction technologies. Full article

Fine migration is widely recognized as a primary cause of production decline in unconsolidated sandstone reservoirs. Migrated fines may accumulate within pore throats and obstruct flow channels, or they may be transported into the wellbore with the produced fluids, leading to operational issues such as wellbore plugging, pump sticking, and equipment abrasion. Despite extensive studies on fine migration, the role of particle wettability has received limited attention. In this study, the mineralogical composition of formation particles was first characterized using X-ray diffraction (XRD) and quantitative clay analysis. Surface modification experiments were then conducted to investigate the effect of hexadecylamine (HDA) on particle wettability and to determine the optimal reaction conditions. Surface characterization techniques were employed to elucidate the modification mechanism. Subsequently, sand-packed tube displacement experiments were performed to evaluate the influence of wettability alteration on fine migration behavior. The underlying mechanisms were further interpreted through interfacial thermodynamic analysis. Two potential field application schemes are proposed to facilitate practical implementation in oilfield operations. The results indicate that the water contact angle of formation particles increased from 0° to 150° when treated with 0.8 wt% HDA for 24 h. Surface characterization confirms that HDA molecules were physically adsorbed onto the particle surfaces. Displacement experiments demonstrate that the permeability reduction rate decreases significantly with increasing particle hydrophobicity. Thermodynamic analysis suggests that the work of adhesion on the modified particle surface was reduced by 93.3%, thereby weakening fluid–particle interfacial coupling and suppressing fine mobilization. This study provides a wettability-based approach for mitigating permeability damage caused by fine migration in unconsolidated sandstone reservoirs. Full article

High-viscosity reservoirs are widely distributed across various countries with abundant reserves. However, their high resin and asphaltene content leads to elevated oil viscosity and low recovery rates. Conventional chemical flooding techniques are unsuitable for the development of such high-viscosity oilfields. Chemical viscosity reduction technologies face challenges such as low viscosity reduction efficiency, poor economic feasibility, and unclear mechanisms. Microbial-assisted chemical viscosity reduction represents a relatively novel approach. This study systematically investigated the enhanced oil recovery performance of a microbial-assisted chemical viscosity reducer. The results demonstrated that this microbial-assisted chemical viscosity reducer achieved a viscosity reduction rate exceeding 85% for five different crude oil samples. It effectively altered the wettability of oil-wet surfaces, improved the oil film stripping rate by 50–65% compared to pure chemical flooding agents, and achieved ultra-low oil–water interfacial tension on the order of 10⁻³ mN/m with crude oil, leading to an enhanced oil recovery (EOR) enhancement of 22–26%. The underlying mechanism is that viscosity-reducing bacteria degrade asphaltene in heavy oil, thereby weakening intermolecular forces. Their metabolites enhance the emulsion stability of the chemical viscosity reduction process. Chemical viscosity reducers enhance the physiological cycle and metabolic activity of microorganisms while also emulsifying and dispersing heavy oil and improving emulsion stability. Therefore, this novel microbial-assisted chemical viscosity reduction technology offers a new and effective EOR method for high-viscosity reservoirs. Full article

The prediction of drying kinetics in hygroscopic biological materials remains challenging due to the strong coupling between internal moisture diffusion, evolving surface wettability, material deformation and thermolabile bioactive compounds degradation. In this context, periodic temperature variations are inherent to many industrial and solar drying systems, yet most experimental and modeling studies evaluate product quality under constant-temperature conditions. This work provides a demonstration that periodic drying can alter quality degradation pathways in ways that may not be captured by constant-temperature experiments. A coupled non-isothermal lattice Boltzmann method (LBM) model for heat and moisture transport was integrated with a Weibull kinetic formulation to describe the degradation of total carotenoids, total polyphenols, and antioxidant activity in carrot slices. Validation against experimental data across 50–70 °C demonstrates excellent agreement (R² > 0.96 for moisture ratio; quality retention within ±2% of the literature values). Seven drying scenarios were systematically evaluated: constant temperature (60 °C), fast and slow periodic oscillations, high-amplitude cycles, a mixed strategy combining constant initial drying with subsequent oscillations, and two intermittent ON/OFF profiles. Results reveal that while total polyphenol degradation within the present model is constrained to ~13.3% retention under the adopted kinetic parameters, carotenoid and antioxidant retention are highly sensitive to temperature history. The mixed strategy (60 °C for 2 h followed by 50–60 °C oscillations) achieves the highest quality retention (TC: 51.6%, AA: 34.4%) while requiring the lowest energy input (0.512 kJ), outperforming constant drying (TC: 48.8%, AA: 32.9%, 0.563 kJ). Conversely, high-amplitude intermittent drying (70/25 °C) accelerates carotenoid degradation (TC: 46.7%) despite shorter drying time (8.81 h), and low-amplitude intermittent cycling (65/55 °C) yields the poorest mean quality (31.4%) with the highest energy consumption (0.583 kJ). The framework reveals that oscillation frequency critically determines quality outcomes: slow cycles (8 h period) marginally improve retention, while fast cycles (2 h) offer no benefit over constant drying. These findings provide quantitative insights toward the design of drying strategies, demonstrating that optimal strategies must account for the coupling between temperature history and moisture-dependent vulnerability, with the mixed strategy emerging as the best-performing strategy among the tested scenarios. Full article

Coal-bed gas well production is too low to realize a highly efficient exploitation of the #8 coal seam in the Shanxi formation in the Nalin region. Based on the reservoir characteristics, the designed poly-aromatic-grafted silicon-quantum-dot-based desorption agent (PQS) has been developed. Then, the adsorption/desorption behavior of CBM on the coal surface under the influence of this active chemical has been studied, and the synergy effect with an anionic–nonionic surfactant to desorption of CBM has also been discussed. The results show that the developed poly-aromatic-grafted silicon quantum dot, with a median size of 4.9 nm and +5.6 mV of zeta potential in neutral condition, has a significant emission peak with 470 nm at the excitation of 380 nm and 150,000 mg/L of salinity resistance, which also generates a strong adsorption capacity on the coal surface. A promoting effect to desorption of CBM for PQS nanofluid is exhibited and the Langmuir pressure is obviously increased. However, when the PQS nanofluid is synergized with an anionic–nonionic surfactant, the desorption of CBM is further improved and the wettability of the coal surface is altered from 78.2° to 84.2°. The desorption rate for this compound system reached 65.3%. It can be found that combining the quantum size, π–π stacking, π–π conjugation, and the synergy effect between PQS nanofluid and surfactant fluid with the traditional intermolecular force has a stronger capacity for promoting desorption of CBM than the conventional desorption agent. This study provides guidance for the molecular design of the desorption agent for deep coal rock and the application of silicon quantum dots. Full article

Low-salinity water flooding (LSWF) has been widely investigated as an enhanced oil recovery (EOR) method for carbonate reservoirs; however, the relative contributions of wettability alteration and oil–brine interfacial tension (IFT) reduction remain poorly understood, particularly under strongly oil-wet conditions. This study systematically investigates the physicochemical mechanisms governing oil recovery during hybrid LSWF–surfactant flooding in oil-wet carbonate systems. Oil-wet Indiana limestone cores were used as representative carbonate reservoir rocks. Seawater and its diluted analogs were employed as base brines and combined with anionic and cationic surfactants at varying concentrations. Zeta potential and pH measurements were conducted to characterize electrostatic interactions at the rock–brine and oil–brine interfaces, while dynamic contact angle and pendant-drop IFT measurements were used to quantify wettability evolution and fluid–fluid interactions. Core flooding experiments were subsequently performed to link interfacial phenomena to macroscopic oil recovery behavior. The results demonstrate that brine dilution induces more negative surface charges at both interfaces, promoting double-layer expansion and electrostatic repulsion, which stabilizes the aqueous film and drives wettability alteration toward a water-wet state. The addition of anionic surfactants further amplifies this effect by increasing surface charge negativity, whereas cationic surfactants preferentially adsorb onto the negatively charged rock surface, limiting wettability alteration despite producing greater IFT reduction. Sulfate ions enhance wettability alteration by facilitating divalent cation interactions with adsorbed oil components; however, excessive sulfate concentrations lead to precipitation-induced flow impairment. Core flooding results reveal that diluted seawater combined with an anionic surfactant yields the highest incremental oil recovery. Our findings conclusively demonstrate that wettability alteration—rather than IFT reduction—is the more dominant recovery mechanism in oil-wet carbonate reservoirs under the investigated conditions. These results provide mechanistic guidance for optimized brine and surfactant design in hybrid LSWF–chemical EOR applications. Full article

This study aims to reveal the mechanism of a novel method for fabricating hierarchical microstructured hydrophobic surfaces. Specifically, plasma shock waves induced by laser ablation are applied to the workpiece to replicate the microstructures on the mold surface, thus obtaining primary microstructures. Meanwhile, the material splashing effect induced by laser ablation is utilized to form secondary microstructures on the basis of the primary microstructures. Subsequently, fluorination treatment and aging treatment are adopted to alter the chemical composition of the hierarchical microstructures on the workpiece surface, thereby reducing the surface energy and enhancing hydrophobicity. In addition, this study investigates the effects of a different number of laser shocks, laser fluence and mold periods on the forming results. Under a laser fluence of 28.97 J/cm², within the range of one to five laser shocks, the forming effect of the aluminum foil workpiece improves with the increase in the number of laser shocks. When the number of laser shocks is set to 3, within the laser fluence range of 19.1–76.39 J/cm², the forming result of the aluminum foil workpiece is enhanced as the laser fluence increases. The larger the mold period, the better the forming effect of the workpiece. An analysis of aging treatment and fluorination treatment reveals their impacts on the workpiece through assessments of wettability, surface chemical composition, and surface morphology. The findings reveal that both aging and fluorination treatments significantly enhance the contact angle of the aluminum foil workpiece, all while preserving its original surface structure. The main changes occur in terms of element content and chemical composition, and a large number of non-polar groups are generated on the workpiece surface after the modification treatments. Full article

Microbial biosurfactants, derived from diverse aquatic and extreme ecosystems, offer a sustainable and environmentally compatible strategy for enhanced oil recovery by fundamentally altering subsurface rock wettability. These biologically produced amphiphiles can efficiently transform oil-wet rock surfaces into water-wet states, thereby mobilizing otherwise trapped crude oil. The primary aim of this review is to provide an integrative understanding of how these biomolecules function at the interface between aquatic microbial ecology and subsurface petroleum engineering, with a particular focus on wettability alteration as a key mechanism for enhancing oil recovery. This review surveys major biosurfactant classes—glycolipids, lipopeptides, and polymeric bioemulsifiers—and their core mechanisms, emphasizing their relevance to challenging reservoir conditions such as high temperature and salinity. A detailed assessment is devoted to persistent hurdles such as stability, adsorption onto rock formations, and economic scalability. Future prospects center on three key approaches: advancing synergistic “bio-hybrid” systems that integrate biosurfactants with complementary agents such as biopolymers and nanomaterials; achieving cost-effective production through the valorization of waste feedstocks; and expanding targeted bioprospecting of microbial diversity from extreme aquatic environments. Together, these strategies are reviewed to drive the advancement of robust, green microbial-enhanced oil recovery (MEOR) technologies, charting a course from fundamental insights to field-scale implementation. Full article

Superhydrophobic materials have clear potential for mitigating rain/humidity-induced damage to cultural heritage. In the present study, the wetting properties of Paraloid B72 were tailored to achieve superhydrophobicity by incorporating modified calcium carbonate (CaCO₃) nanoparticles (NPs). B72 is a well-established conservation product while CaCO₃ is chemically compatible with calcareous materials commonly found in cultural heritage buildings and objects. Initially, the wettabilities of CaCO₃ NPs, functionalised with caproic (C6), caprylic (C8), lauric (C12), myristic (C14), palmitic (C16), and stearic (C18) acid, were evaluated by measuring water contact angles (CAs) on NP pellets. For NPs with short hydrocarbon chains, CA increased with chain length, from 66.3° for CaCO₃-C6 to 118.0° for CaCO₃-C12 NPs. For NPs with longer chains, CA remained stable and around 118°. Based on these results, CaCO₃-C12 NPs were selected for further investigation and subjected to transmission electron microscopy analysis, which revealed chain-like agglomerates of aggregated nanocrystallites (5–10 nm) forming 40–150 nm polycrystalline NPs. Scanning transmission electron microscopy combined with elemental mapping revealed a homogeneous distribution of Ca, C, and O within the NPs. Next, CaCO₃-C12 NPs were dispersed in B72 solutions and sprayed onto limestone, which was employed as a model calcite-rich substrate. At optimal NP concentration, the resulting composite coating exhibited superhydrophobicity (CA > 150°), while it induced minimal colour alteration to limestone and effective resistance to capillary water absorption. The fluorine-free coating also demonstrated good durability against UV exposure, drop impact, salt attack, freeze–thaw cycles, tape peeling, drop pH variations, and thermal treatment. Full article

This study examines the impact of synthesized silica nanofluid on wettability and interfacial tension in sandstone reservoirs to enhance oil recovery. The parameters of the nanofluid are assessed using methods such as a DLS Zetasizer, contact angle measurements, and tensiometer. Preliminary findings indicate stable nanoparticle distribution and further results show significant wettability alterations and reduced interfacial tension, suggesting the nanofluid’s potential in optimizing fluid–rock interactions for enhanced oil recovery. This study highlights the potential of nanotechnology in the petroleum industry, provides a new understanding of fluid behavior in porous media, and increases the understanding of nanofluid-enhanced reservoir engineering. Full article

Poly(ethylene terephthalate) (PET) is a widely used commodity polymer owing to its low cost, excellent mechanical properties, and high processability. Chemical modification of PET surfaces to impart specific functionalities represents an effective strategy for transforming PET into high-value-added materials without altering its bulk properties. In this study, we investigated the surface functionalization of PET substrates using surface-initiated atom transfer radical polymerization (SI-ATRP). ATRP initiation sites were introduced onto PET surfaces through mild surface hydrolysis followed by polyethyleneimine coating. To further enhance the grafting density, an inimer-based strategy was employed, in which a bifunctional monomer containing both a polymerizable group and a latent initiation site was used to form hyperbranched polymer structures on the PET surface, thereby amplifying the number of active initiation sites. Using these modified PET substrates, SI-ATRP of functional methacrylate monomers was successfully carried out. Grafting of poly(2,2,2-trifluoroethyl methacrylate) imparted highly hydrophobic surface properties, yielding water contact angles above 120°, whereas grafting of poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride) produced hydrophilic surfaces with contact angles below 20°. Surface characterization by X-ray photoelectron spectroscopy confirmed successful graft polymerization and effective surface coverage. While the macroscopic wettability was primarily governed by the chemical nature of the grafted polymers, the inimer-based initiation-site amplification significantly enhanced the surface electrostatic properties of the polycationic polymer–grafted surfaces, increasing the ζ-potential from approximately +20 mV to over +100 mV. Antibacterial tests using Escherichia coli K-12 as a model bacterium demonstrated that PET substrates grafted with poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride) exhibited clear contact-active antibacterial activity, achieving up to 2-log reduction in viable bacterial counts after 3 h of contact incubation. These results highlight the importance of molecular-level control of grafting architecture and surface electrostatic properties in the design of functional antibacterial PET surfaces. Full article

Zirconia is a material that mimics human teeth and has been extensively studied and applied. This study investigated the surface modifications of dental zirconia induced by two UV-C wavelengths (222 and 254 nm). A total of 72 zirconia specimens were prepared and divided into groups for irradiation at varying distances (1, 6, 12 cm) and durations (40, 120, 480 and 1440 min), with three specimens retained as untreated controls. Surface changes were assessed by measuring colour difference (ΔE) and water contact angle, and by analyzing surface morphology and elemental composition using SEM and EDX, and XRD was employed to determine the crystalline structure. The results showed that both wavelengths induced clinically perceptible colour changes (ΔE > 2.0), with the most pronounced effect at 6 cm for 222 nm and 1 cm for 254 nm. WCA decreased significantly with irradiation time, showing a linear correlation with log(time), and 222 nm irradiation yielded lower WCA than 254 nm. While SEM revealed no morphological changes, both UV treatments significantly increased the Zr/O ratio compared to the control. XRD tests confirmed that UV-C irradiation does not damage the zirconium oxide crystal structure. It is concluded that both UV-C wavelengths can alter the colour and enhance the wettability of zirconia; these modifications are particularly relevant for dental restorative applications, specifically in the fabrication of anterior tooth crowns, where achieving a natural tooth-like appearance is desired. Full article

A tissue-engineered heart valve is a fully functional tissue facilitated through the cultivation of autologous cells on appropriate scaffolds. Scaffold’s surface charge and wettability are the main factors that significantly affect cell adhesion, which is known to be favourable on hydrophilic surfaces. Moreover, biocompatible scaffolds that induce minimal immunogenic response are also essential for successful tissue engineering (TE). However, commonly used biocompatible polymers with preferable bulk properties lack desirable surface properties. For example, poly-ε-caprolactone (PCL), which is widely used as a scaffold in TE, is known for its satisfying structural and mechanical properties, but due to its surface characteristics, cell attachment and, consequently, cell growth on this polymer are limited. In this study, we investigated the possible effect of H₂-N₂ plasma treatment on the surface wettability of electrospun PCL nanofibres to see the feasibility of improvement in cell adhesion and proliferation. Our results showed an increase in the hydrophilicity of the 650 nm PCL specimens after plasma treatment, which was followed by a significant enhancement in cell attachment without altering PCL mechanical properties. Plasma surface modification is a promising approach that can be used to improve hiMSCs growth without altering the desired bulk properties and fibre morphology of 650 nm PCL specimens. Full article