Search Results (68)

The upper Permian Dalong Formation in western Hubei Province is a crucial strategic successor for shale gas development in South China. However, the geological controls on reservoir pore development, particularly the influence of organic–inorganic interactions on the pore system, remain poorly understood. This restricts the precise optimization of shale gas exploration targets in this formation. To investigate the pore development characteristics and main controlling factors of the Dalong Formation shale reservoirs, this study takes the DFS from the Shuanghe section in western Hubei as the research object. X-ray diffraction (XRD), argon-ion polishing-scanning electron microscopy (SEM), and N₂/CO₂ gas adsorption–desorption technologies were integrated to achieve qualitative characterization and quantitative assessment of the pore network, with analyses of pore size distribution. The results show that the pores of the DFSs are dominated by interparticle pores and organic matter pores, and the pore structures of organic-rich and organic-lean shales exhibit significant differentiation characteristics. The quartz in the DFSs are mainly of diagenetic origin, and authigenic quartz cementation blocks primary intergranular pores, exerting a significant negative effect on pore development. In contrast, the smectite-to-illite transformation promotes the development of interlayer micropores, leading to a good positive correlation between clay mineral content and micropore volume, as well as specific surface area. Organic matter abundance is the core controlling factor for the construction of micro–nano pore networks. This study clarifies the dominant mechanisms of pore development driven by organic–inorganic interactions in the DFS. Authigenic diagenetic quartz impedes pore development, while smectite-to-illite transformation promotes micropore formation. Organic matter abundance is the dominant control on the micro-nanopore system. This study lays a critical geological theoretical foundation for the exploration evaluation and target selection of shale gas in the Dalong Formation. Full article

The marine shale of the Longmaxi Formation is the main layer for shale gas exploration and development in the Sichuan Basin. That said, the pore structure in the Longmaxi shale is strongly heterogeneous, and how these pores form and are preserved remains unclear—which limits our understanding of what makes a good reservoir and holds back efficient shale gas development. To investigate the coupling relationship between hydrocarbon generation and pore evolution in marine shale, medium-maturity shale from the Longmaxi Formation in NE Sichuan was collected for thermal maturation experiments. Shale samples and pyrolysis products from different evolutionary stages were obtained for a series of analyses, including gas composition and pore structure. The influence of organic hydrocarbon generation and inorganic diagenesis on the development of shale nanopores was revealed, and a pore evolution model for marine shale was established. The results show the following: (1) The hydrocarbon generation process of medium-maturity marine shale consists of three stages. The maximum methane yield is 362.58 mL/g. (2) As the thermal maturity increases, the quartz content shows a gradual increase, while the content of clay minerals, feldspar, and carbonate minerals decreases. (3) As the thermal maturity increases, pore evolution is observed in four stages: “slow decrease,” “rapid increase,” “relatively stable,” and “slow decrease.” The first stage is characterized by pore reduction dominated by intense compaction. The second stage is dominated by pore expansion driven by mineral transformation and dissolution. The third stage is the pore preservation stage, during which continuous natural gas generation occurs. The fourth stage is characterized by pore reduction, mainly driven by weak compaction. This study has enriched the theoretical understanding of the dynamic evolution of shale pores, providing a theoretical basis for the research on the formation and enrichment mechanism of shale gas and the exploration practice of shale gas reservoirs. Full article

This work examines the micromechanical response of Al₂O₃/IF-WS₂ (IF-inorganic fullerene-like) composite coatings formed on the EN AW 5251 aluminium alloy by anodic oxidation. The resulting amorphous oxide layer contains a nanopores system that can be filled with IF-WS₂ particles, provided the modifier is properly dispersed. Because commercial IF-WS₂ powders exhibit strong agglomeration, a high-intensity ultrasonic treatment was applied to enhance particle separation before incorporation. The influence of newly established incorporation parameters was assessed using a two-level experimental design. As part of the research, analyses of the microstructure, micromechanical, and sclerometric properties were performed. Cross-sectional SEM observations confirmed the presence of IF-WS₂ within the oxide structure and revealed differences in particle distribution, depending on the incorporation technique used. The results indicate that although microhardness and Young’s modulus are largely insensitive to the nanopowder incorporation method, the interaction between the anodising current density and the incorporation technique significantly influences the strain energy components and tribological response of the coatings. These findings suggest that appropriately selected processing parameters can be used to tailor the mechanical and tribological properties of Al₂O₃/IF-WS₂ coatings to specific loading conditions and functional requirements, rather than striving for a single, universal, optimal processing configuration. Full article

Shale oil reservoirs are complex multi-scale nanoporous media where fluid transport is governed by coupled micro-mechanisms, demanding a robust modeling framework. This study presents a novel fluid–solid coupling (FSC) numerical model that rigorously integrates the three primary scale-dependent transport phenomena: adsorption in organic nanopores, slip effects in inorganic micropores, and stress-sensitive conductivity in fractures. The model provides essential quantitative insights into the dynamic interaction between fluid withdrawal and reservoir deformation. Simulation results reveal that microstructural properties dictate the reservoir’s mechanical stability. Specifically, larger pore diameters and higher porosity enhance stress dissipation, promoting long-term stress relaxation and mitigating permeability decay. Crucially, tortuosity governs the mechanical response by controlling pressure transmission pathways: low tortuosity causes localized stress concentration, leading to rapid micro-channel closure, while high tortuosity ensures stress homogenization, preserving long-term permeability. Furthermore, high fracture conductivity induces a severe, heterogeneous stress field near the wellbore, which dictates early-stage mechanical failure. This work provides a powerful, mechanism-based tool for optimizing micro-structure and production strategies in unconventional resources. Full article

The characteristics of shale oil reservoirs, such as low porosity, ultra-low permeability, and complex pore structure, are key factors affecting effective pore space and fluid migration. This study focuses on medium-to-high maturity mud shale in the Qing-1 Member of the Qingshankou Formation in the Gulong Sag. Using methods such as XRD, organic geochemical testing, and multi-scale pore characterization (FE-SEM, low-temperature CO₂–N₂ adsorption, high-pressure mercury intrusion, and CT scanning), the lithofacies and pore structure were comprehensively characterized, and their controlling factors were analyzed. The results indicate: (1) The mineral composition is dominated by felsic and clay minerals. Based on a three-level classification standard of “mineral composition–sedimentary structure–organic matter abundance”, seven subfacies were identified, with the dominant lithofacies being Felsic–Clayey Mixed Shale and Felsic-bearing Clay Shale. (2) The reservoir space consists of inorganic pores, organic pores, microfractures, and a small amount of other auxiliary pores, exhibiting “bimodal” pore size characteristics. Micro–mesopores dominate adsorption, while macropores/microfractures control free oil seepage; mesopores contribute the most to pore volume. (3) In terms of oil-bearing potential, Felsic–Clayey Mixed Shale shows prominent movable oil potential (average OSI: 133.08 mg/g; S₁ > 2 mg/g, OSI > 100 mg/g). (4) CT-based 3D stick-and-ball models indicate that Felsic–Clayey Mixed Shale has the best connectivity (connectivity rate: 30.63%), with throat radii mostly ranging from 1–15 μm and pore radii from 2–20 μm. (5) Pore development is synergistically controlled by total organic carbon (TOC, with an optimal range of approximately 1–2.5%), clay/felsic mineral ratio, and bedding/structural fractures. The formation of the pore system is the result of dynamic coupling of organic–inorganic interactions during diagenetic evolution: intergranular pores of clay minerals and microfractures jointly contribute to specific surface area and pore volume, while bedding fractures connect nanopore clusters to enhance seepage capacity. This study improves the integrated understanding of dominant lithofacies, pore structure, and oil-bearing potential in the Qing-1 Member of the Gulong Sag, providing a basis for sweet spot evaluation and development optimization. Full article

Phenolic aerogel holds great promise for applications in thermal protection against ablation, and constructing inorganic–organic hybrid networks is an effective strategy to enhance its oxidation and ablation resistance. This study introduces a stepwise hybridization strategy for the preparation of SiO₂–ZrO₂–phenolic resin aerogels (SZPA). First, nano-silica sol and nanometer-scale zirconia were physically blended to form a uniformly dispersed mixture. Subsequently, the modified silica was incorporated into a phenolic resin solution to construct a three-dimensional hybrid silica–phenolic network framework. Nano-sized zirconia was then uniformly dispersed within the matrix as a physical reinforcing phase through high-shear dispersion. Finally, the SZPA with a hierarchical nanoporous structure was obtained via ambient-pressure drying. Owing to its unique hybrid network structure, the aerogel exhibits markedly improved properties: the thermal conductivity is as low as 0.0419–0.0431 W/(m·K) (a reduction of approximately 24%), and the specific surface area is as high as 190–232 m²/g (an increase of approximately 83%). Meanwhile, the inorganic network considerably enhances the residual mass at elevated temperatures, as well as the oxidation resistance and thermal stability of the matrix. Among the tested materials, the SZPA-4 exhibited outstanding thermal insulation capability at high temperatures; its back surface temperature reached only 74.4 °C after 600 s of exposure to a 1200 °C butane flame. This study provides a feasible route for the preparation of high-performance phenolic-based composite aerogels for aerospace thermal protection systems, thereby expanding their potential applications in extreme thermal environments. Full article

To clarify the organic matter enrichment regularity of Permian shales in the Kaijiang–Liangping Trough, as well as the differential characteristics of their reservoir lithology, mineral assemblage, and nanopore structure—and thereby provide a geological basis for the exploration and development of Permian marine shales in the eastern Sichuan Basin—core samples from different depths of the Wujiaping Formation and Dalong Formation in Well DY-1H were analyzed using a series of micro–nano technical research methods, including whole-rock X-ray diffraction, major/trace element analysis, conventional porosity-permeability measurement, high-pressure mercury intrusion porosimetry, nitrogen adsorption, and field emission scanning electron microscopy. Research finds that the Dalong Formation shale contains Type I organic matter with high abundance, whereas the Wujiaping Formation shale is dominated by Type II₂ organic matter. The Wujiaping Formation experienced stronger terrigenous input and higher weathering intensity, while the Dalong Formation was deposited under persistently anoxic conditions, in contrast to the frequent oxic–anoxic alternations in the Wujiaping Formation. Paleoproductivity indicators suggest higher productivity in the Dalong Formation than in the Wujiaping Formation. Mo/TOC ratios below 4.5 indicate deposition in a strongly restricted water body. Enrichment factors of multiple elements further support the enhanced paleoproductivity of the Dalong Formation. The Dalong Formation shale has higher contents of quartz and carbonate minerals, while the Wujiaping Formation shale has a higher content of clay minerals. The Wujiaping Formation shale is more developed with inorganic micropores, whereas the Dalong Formation shale is characterized by more developed organic nanopores. During the sedimentary period of the Dalong Formation shale, the paleoproductivity was high, the sedimentary waterbody had high reducibility and restriction, and the reservoir was well-developed with nanopores. The Dalong Formation is a more favorable interval for Permian shale gas exploration and development in the Kaijiang–Liangping Trough. Full article

New energy vehicles face a critical challenge in balancing the thermal safety management of high-specific-energy battery systems with the simultaneous improvement of energy density. With the large-scale application of high-energy-density systems such as silicon-based anodes and solid-state batteries, their inherent thermal runaway risks pose severe challenges to battery thermal management systems (BTMS). Currently, the thermal insulation performance, temperature resistance, and fire protection capabilities of flame-retardant materials (e.g., foam cotton, fiber felts) used in automotive batteries are inadequate to meet the demands of intense combustion and high temperatures generated during thermal failure in high-energy-density batteries. Against this backdrop, thermal insulation and fireproof aerogel materials are emerging as a revolutionary solution for the next generation of power battery thermal protection systems. Leveraging their nanoporous structure’s exceptional thermal insulation properties (thermal conductivity of 0.013–0.018 W/(m·K) at room temperature) and extreme fire resistance (temperature resistance > 1100 °C/UL94 V-0 flame retardancy), aerogels are gaining prominence. This article provides a systematic review of thermal runaway phenomena in automotive batteries and corresponding protective measures. It highlights recent breakthroughs in the selection of material systems, optimization of preparation processes, and fiber–matrix composite technologies for automotive fireproof aerogel composites. The core engineering values of these materials, such as blocking thermal runaway propagation, reducing system weight, and improving volumetric efficiency, are quantitatively validated. Furthermore, the paper explores future research directions, including the development of low-cost aerogel composites and the design of organic–inorganic hybrid composite structures, aiming to provide a foundation and industrial pathway for the research and development of next-generation high-performance battery thermal management systems. Full article

Bionic synthesis technology has made significant breakthroughs in porous functional materials by replicating and optimizing biological structures. For instance, biomimetic titanium dioxide-coated carbon multilayer materials, prepared via biological templating, exhibit a hierarchical structure, abundant nanopores, and synergistic effects. Bionic mineralization further enhances microcapsules by forming a secondary inorganic wall, granting them superior impermeability, high elastic modulus, and hardness. Through techniques like molecular self-assembly, electrospinning, and pressure-driven fusion, researchers have successfully fabricated centimeter-scale artificial lamellar bones without synthetic polymers. In environmental applications, electrospun membranes inspired by lotus leaves and bird bones achieve 99.94% separation efficiency for n-hexane–water mixtures, retaining nearly 99% efficiency after 20 cycles. For energy applications, an all-ceramic silica nanofiber aerogel with a bionic blind bristle structure demonstrates ultralow thermal conductivity (0.0232–0.0643 W·m⁻¹·K⁻¹) across a broad temperature range (−50 to 800 °C). This review highlights the preparation methods and recent advances in biomimetic porous materials for practical applications. Full article

Dewatering and gas production are applied on a large scale in shale gas development. The fundamental mechanisms of water flow in shale nanoporous media are essential for the development of shale oil and gas resources. In this work, we use molecular dynamic simulations to investigate water flow in two different quartz surface ($(10\overline{1}0)\text{-}\alpha$ and $(10\overline{1}0)\text{-}\beta$) nanopores. Results show that the $(10\overline{1}0)\text{-}\beta$ surface exhibits stronger water molecule structuring with a structure arranged in two layers and higher first-layer adsorption density (2.44 g/cm³) compared to the ($(10\overline{1}0)\text{-}\alpha$ surface (1.68 g/cm³). The flow flux under the $(10\overline{1}0)\text{-}\alpha$ surface is approximately 1.2 times higher than that under the $(10\overline{1}0)\text{-}\beta$ surface across various pressure gradients. We developed a theoretical model dividing the pore space into non-flowing, adsorbed, and bulk water regions, with critical thicknesses of 0.14 nm and 0.27 nm for the non-flowing region, and 0.15 nm for the adsorbed region in both surfaces. This model effectively predicts velocity distributions and volumetric flow rates with errors generally below 5%. Our findings provide insights into water transport mechanisms in shale inorganic nanopores and offer practical guidance for numerical simulation of shale gas production through dewatering operations. Full article

In order to better understand the micropore structure of shale reservoir in Jiyang Depression, permeability damage test, low temperature nitrogen adsorption and scanning electron microscopy (SEM) were carried out on six cores in the target block. The adsorption isotherms were analyzed by Frenkel–Halsey–Hill (FHH) model, and the fractal dimensions of different layers were calculated. The results show that the shale pore system is mainly composed of organic nanopores, inorganic nanopores and micro-fractures. The inorganic pores are mainly distributed around or inside the mineral particles, while microcracks are commonly found between mineral particles or at the organic–mineral interface. Organic pores are located within or between organic particles. The results of nitrogen adsorption show that the shale pores are mainly H2/H3 hysteresis loops with wedge, plate or ink bottle shapes. The pore structure is highly complex, and the fractal dimension is high. The mean D1 fractal dimension, which represents pore surface roughness, is 2.3788, and the mean D2 fractal dimension, which represents pore structure complexity, is 2.7189. The fractal dimension is positively correlated with specific surface area and total pore volume and negatively correlated with average pore radius. The permeability damage rates of the N layer, B layer, and F layer are 17.39%, 20.2%, and 21.6%, respectively. The contact Angle of the core decreases with the increase in water skiing time. In this study, the micropore structure of different formations in Jiyang Depression is compared and analyzed, which provides valuable insights for the optimization and differentiated development of shale oil and gas resources. Full article

Research has delved into the main controlling factors for the evolution of the pore-fracture structure in deep coal samples. The gas content is influenced by multiple factors, among which the pore-fracture structure in deep coal samples stands as one of the key determinants. To ascertain the evolution of the pore-fracture structure and the main controlling factors of the gas content in deep coal samples of the Yan’an Gas Field, 16 coal samples were collected from the Yan’an Gas Field in the Ordos Basin in this study. A series of laboratory tests and analyses were then carried out. According to the test results, the major controlling factors for the evolution of the pore-fracture structure of the samples were analyzed in accordance with the proximate analysis components, maceral components, mineral composition of the coal samples, and R_o,max, in conjunction with the pore volume and specific surface area of nanopores. Meanwhile, based on the in situ desorption experiment, the major controlling factors of the gas content in coal were explored. First, based on the SEM and hand specimen identification, the pore-fracture structure of the samples is relatively well developed. Calcite filling the fractures of samples can be seen in the hand specimens of samples. This indicates that the mineral composition has a very important influence on the evolution of the pore-fracture structure of samples. Secondly, this study indicates that pore-fracture structure evolution is influenced by multiple factors, primarily ash content and fixed carbon. As ash content increased, the mesopore surface area and volume rose across all sample types, with Type C showing the highest increase (78.1% in surface area and 12.4% in volume compared to Type A). Conversely, micropore characteristics declined, with Type C exhibiting a 4.8% drop in surface area and a 4.7% reduction in volume. The R_o,max of the samples is generally higher than 2.8%, which has a multifaceted impact on pore-fracture structure evolution. Finally, the gas content is mainly controlled by pore volume and the specific surface area of nanopores, with industrial components and maceral compositions showing minimal direct influence. This suggests that gas content results from the combined effects of material composition and pore-fracture structure evolution. Inorganic minerals like quartz and calcite indirectly affect gas content by influencing pore structure development—occupying spaces while also creating new pores, especially through calcite dissolution. Conversely, clay minerals generally hinder pore development by filling spaces with limited fracture-forming capacity. The main purpose of this study is to evaluate the gas content of coal samples in Yan‘an Gas Field. There are few studies on this area by previous scholars. Full article

Shale oil reservoirs feature a considerable number of nanopores and complex minerals, and the impact of nano-pore confinement and pore types frequently poses challenges to the efficient development of shale oil. For shale oil reservoirs, CO₂ flooding can effectively lower crude oil viscosity, enhance reservoir physical properties, and thereby increase recovery. In this paper, the CO₂ displacement process in the nanoscale pores of shale oil was simulated through the molecular dynamic simulation method. The performance disparity of quartz and calcite slit nanopores was discussed, and the influences of nanoscale pore types and displacement rates on CO₂ displacement behavior were further analyzed. The results demonstrate that the CO₂ displacement processes of different inorganic pores vary. In contrast, the displacement efficiency of light oil components is higher and the transportation distance is longer. Intermolecular interaction has a remarkable effect on the displacement behavior of CO₂ in nanopores. On the other hand, it is discovered that a lower displacement rate is conducive to the miscible process of alkane and CO₂ and the overall displacement process of CO₂. The displacement efficiency drops significantly with the increase in displacement velocity. Nevertheless, once the displacement speed is extremely high, a strong driving force can facilitate the forward movement of alkane, and the displacement efficiency will recover slightly. Full article

Accurately describing the behavior of a gas-water two-phase flow in shale gas reservoirs is crucial for analyzing production dynamics in the field. Current research generally lacks consideration of the differences in physical properties and adsorption characteristics between the oleophilic organic matrix and the hydrophilic inorganic matrix. This study considers the organic matrix system as a single-phase gas flow, while the inorganic matrix and fracture systems involve a gas-water two-phase flow. Taking into account the impact of the adsorbed water layer on permeability at the surface of nanoscale pores in an inorganic matrix, the model comprehensively incorporates multiple mechanisms such as adsorption-desorption, the slippage effect, and Knudsen diffusion in the organic matrix and clay minerals. A multiscale gas-water two-phase comprehensive flow model for shale gas reservoirs has been established, and the results of the numerical model were validated against commercial software and actual field data. Simulation results over 1000 days indicate that early production from gas wells is primarily supplied by fractures, whereas free gas or desorbed gas from inorganic and organic matrices gradually contributes to the flow during the middle and later stages of production. As the Langmuir pressure and volume in the organic matrix and clay minerals increase, so does the corresponding gas production. The adsorbed water layer on the surface of inorganic nanopores reduces permeability, leading to a decrease in single-well cumulative gas production by 8.41%. The impact of the adsorbed water layer on gas production cannot be overlooked. The simulation method proposed in this study provides theoretical support for analyzing the gas-water two-phase flow behavior in shale gas reservoirs. Full article

CO₂ injection in shale reservoirs is more suitable than the conventional recovering methods due to its easier injectivity and higher sweep efficiency. In this work, Grand Canonical Monte Carlo (GCMC) simulation is employed to investigate the adsorption/desorption behavior of CH₄-C₄H₁₀ and CH₄-C₄H₁₀-CO₂ mixtures in organic and inorganic nanopores during pressure drawdown and CO₂ huff and puff processes. The huff and puff process involves injecting CO₂ into the micro- and mesopores, where the system pressure is increased during the huffing process and decreased during the puffing process. The fundamental mechanism of shale gas recovery using the CO₂ injection method is thereby revealed from the nanopore-scale perspective. During primary gas production, CH₄ is more likely to be produced as the reservoir pressure drops. On the contrary, C₄H₁₀ tends to be trapped in these organic nanopores and is hard to extract, especially from micropores and inorganic pores. During the CO₂ huffing period, the adsorbed CH₄ and C₄H₁₀ are recovered efficiently from the inorganic mesopores. On the contrary, the adsorbed C₄H₁₀ is slightly extracted from the inorganic micropores during the CO₂ puffing period. During the CO₂ puff process, the adsorbed CH₄ desorbs from the pore surface and is thus heavily recovered, while the adsorbed C₄H₁₀ cannot be readily produced. During CO₂ huff and puff, the recovery efficiency of CH₄ is higher in the organic pores than that in the inorganic pores. More importantly, the recovery efficiency of C₄H₁₀ reaches the highest levels in both the inorganic and organic pores during the CO₂ huff and puff process, suggesting that the CO₂ huff and puff method is more advanced for heavier hydrocarbon recovery compared to the pressure drawdown method. In addition to CO₂ storage, CO₂ sequestration in the adsorbed state is safer than that in the free state. In our work, it was found that the high content of organic matter, high pressure, and small pores are beneficial factors for CO₂ sequestration transforming into adsorbed state storage. Full article