Search Results (122)

The Ordos Basin hosts significant shale gas resources in China, yet its marine-continental transitional sedimentary setting causes intense reservoir heterogeneity that severely hinders accurate sweet spot identification in the Permian Shanxi Formation. This study aims to reveal the synergistic controls of lithofacies, mineralogy, and organic matter on shale gas sweet spot formation in the southern Yishan Slope of the eastern Ordos Basin. A multi-dimensional characterization approach was adopted, integrating drilling/logging data and systematic core analyses including X-ray diffraction (XRD), organic geochemical testing, porosity/permeability measurement, and on-site gas content desorption, to quantify reservoir heterogeneity across lithofacies, mineralogy, organic geochemistry, and petrophysical properties. The results show that three lithofacies associations are identified in the target interval: mud-wrapped sand, sand-mud interbedding, and sand-wrapped mud, among which sand-mud interbedding and mud-wrapped sand associations exhibit higher total organic carbon (TOC) contents and strong inter/intra-well heterogeneity. The organic matter in the reservoir is dominated by Type III kerogen, with TOC values ranging from 0.04% to 12.15%, and the Shan 2 Member shows significantly higher average TOC (2.55%) than the Shan 1 Member (1.36%). The reservoir is characterized by ultra-low porosity (average of 0.77%) and low permeability (average of 0.26 × 10⁻³ μm²), with mesopores and macropores contributing over 99% of the total pore volume and showing a significant positive correlation with gas content. Quartz (average of 34.86%) and clay minerals present strong vertical heterogeneity, with the Shan 2 Member being more heterogeneous than the Shan 1 Member due to differences in sedimentary environment evolution. A TOC threshold of 1.5% is determined for sweet spot identification in the study area, and shale gas sweet spots are synergistically controlled by high TOC abundance, moderate brittle mineral content, and 0.1–3 m thick sandy interbeds. This study enriches the theoretical understanding of marine-continental transitional shale reservoirs and provides a scientific basis for sweet spot prediction and development optimization in similar heterogeneous shale gas systems worldwide. Full article

The heterogeneity of pore structure in deep coal reservoirs is a critical factor controlling the storage and transport capacity of coalbed methane (CBM). However, the fundamental control exerted by macrolithotypes remains inadequately quantified. This study systematically investigates the No. 8 coal seam of the Taiyuan Formation in the Daniudi gas field, Ordos Basin, using an integrated multi-technique approach including high-pressure mercury intrusion (HPMI), low-temperature N₂ adsorption (LTGA-N₂), and low-pressure CO₂ adsorption (LPGA-CO₂). Results reveal a consistent bimodal pore structure across all samples, dominated by well-developed micropores and macropores, whereas mesopores are relatively underdeveloped. More importantly, a clear macrolithotype control is established: as coal brightness decreases from bright to dull coal, the proportions of micropores and macropores decline significantly, leading to a substantial reduction in total pore volume and specific surface area. Fractal analysis further indicates that dull and semi-dull coals exhibit larger fractal dimensions, reflecting more complex pore structures and stronger heterogeneity compared to bright and semi-bright coals. This heterogeneity shows a positive correlation with ash and mineral contents, but a negative correlation with vitrinite and fixed carbon contents, suggesting that coal composition plays a primary governing role. These findings underscore that bright and semi-bright coals, with their superior micropore storage capacity and well-connected macropore networks, represent the most favorable targets for deep CBM exploration. This work establishes macrolithotype as a practical key indicator for reservoir quality assessment and production strategy optimization in deep CBM plays. Full article

Short dry spells during the rainy season have become increasingly common in Brazil, reinforcing the need for soil water conservation practices. Plastic mulching can enhance plant water use and mitigate abiotic stress. This study evaluates water use efficiency in terms of soil physical quality, root systems, and photosynthetic performance of citrus plants grown in different Inceptisols. The field experiment, in a randomized block design with a split-plot arrangement, was conducted in Lavras, Brazil, and involved citrus (orange) plants from 2012 to 2014. Undisturbed soil samples were collected at depths of 0.00–0.05, 0.20–0.25, and 0.90–0.95 m, two years after the installation of white plastic (WP), black plastic (BP), and no plastic (NP) mulching treatments in two Inceptisol types, totaling 54 samples. The soil water-retention curve, pore size distribution, and soil physical quality indicators were determined, and root system distribution maps were generated using B-splines. Leaf gas exchange was measured under contrasting precipitation conditions. Inceptisol I showed minimal impact from mulching, except for the bulk density and total porosity, which positively correlated with transpiration under BP. In contrast, in Inceptisol II, WP increased photosynthetic rates under low- and high-precipitation conditions but reduced water use efficiency, correlating positively with macropores and negatively with micropores. Plastic mulching reduces physiological stress in citrus and improves soil physical quality, with WP being the most effective across precipitation levels, particularly in less stable soils. Full article

The irreducible water saturation of reservoirs seriously restricts the efficient drainage of unconventional energy sources. NMR logging can be used to determine parameters such as total porosity, effective porosity, irreducible water saturation, and permeability, which play an important role in oil and gas identification. T_{2 cut off} value identification using the NMR T₂ spectrum is the key to clarifying the irreducible water saturation of unconventional reservoirs. In this paper, saturation and centrifugal T₂ spectra of sandstone and coal samples are used to study and calculate the T_{2 cut off} value, with methods including single fractal dimension, multi-fractal dimension, and spectrum morphological discrimination; in addition, the applicability of these three methods in characterizing T_{2 cut off} is discussed. According to the morphological difference of the saturated T₂ spectrum, relationships between morphological parameters and the T_{2 cut off} of four types of sample are described. The parameters related to T_{2 cut off} can be divided into two types: (1) the first type includes morphological parameters main peak position (T_M) and smaller-pore volume percentage (SPVP); with an increase of T_{2 cut off}, T_M increases linearly and SPVP decreases exponentially, and the correlation between SPVP and T_{2 cut off} is stronger than that of T_M. (2) The other type includes fractal parameters D₂ (fractal dimension of larger pore), D₋₁₀ – D₁₀, and D₋₁₀/D₁₀; with the increase of T_{2 cut off}, single and multi-fractal dimensions all increase linearly, and the correlation between D₂ and T_{2 cut off} is stronger than that of the multi-fractal dimension. When calculating the T_{2 cut off} of samples with macro-pores developed, spectrum morphological methods should be used preferentially, while the fractal dimension discrimination methods need be used for the T_{2 cut off} of samples with developed micro-pores. Then, the T_{2 cut off} value prediction and evaluation system are described. The overall results of this work can provide a theoretical basis for the inversion of bound water content in the original formation. Full article

Nymphaea ‘Blue Bird’, a tropical water lily prized for its ornamental appeal, has been less explored as a source of bioactive flavonoids. This study developed an efficient extraction and purification protocol for flavonoids from this plant and compared their distribution and bioactivities across different tissues. Supercritical CO₂ fluid extraction (SFE) proved optimal, yielding 2.56% under conditions of 24.3 MPa, 39 °C, 91 min, and a CO₂ flow rate of 16 L/min. Subsequent purification with HPD500 macroporous resin enhanced flavonoid purity from 3.05% to 11.46%. Among the tissues analyzed, petals contained the highest levels of total flavonoids (6.43 mg/g) and total phenolics (45.71 mg/g), and exhibited the most potent antioxidant (as shown by the lowest EC₅₀ values for ABTS⁺ and DPPH scavenging) and broad-spectrum antibacterial activities (indicated by the lowest MIC and MBC against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans). Antibacterial efficacy was generally superior against Gram-positive bacteria. Widely targeted metabolomics identified 560 metabolites, predominantly flavonols and flavonoids. Principal component and cluster analyses revealed tissue-specific metabolite profiles. KEGG enrichment analysis underscored the significance of the flavonoid biosynthetic pathway, and key differential metabolites—such as luteolin, myricetin, taxifolin, and quercetin—were strongly correlated with the observed bioactivities. These results highlight N. ‘Blue Bird’ petals as a promising source of natural antioxidants and antimicrobials, providing a scientific basis for their future functional applications. Full article

The tight sandstone reservoir of the Fuyu Oil Layer in the Quantou Formation of the Cretaceous in the Bayan Chagan area displays intricate microscopic pore structures and pronounced heterogeneity, limiting hydrocarbon exploration and development efficiency. Utilizing core CT scanning digital core technology integrated with field emission scanning electron microscopy (FE–SEM) and whole-rock/clay mineral X-ray diffraction (XRD) analysis, this research performs multi-scale quantitative characterization on 15 representative rock samples from the study area, systematically elucidating reservoir pore structure diversity and its formation mechanisms. The study demonstrates that reservoirs in the study area can be categorized into three types: A, B, and C, exhibiting progressively declining reservoir performance. Type A reservoirs are characterized primarily by dissolution-formed large to medium pores, where macropores (radius > 5 μm) account for more than 92% of storage capacity, average coordination numbers reach 0.27~0.45, and connectivity is optimal. Type B reservoirs are influenced by siliceous cementation, featuring developed residual intergranular pores, macropore volume share declining to 88%, and coordination numbers decreasing to 0.11~0.20. Type C reservoirs experience intense compaction and illite cementation modification, where micropores (radius < 1 μm) constitute 5.6% numerically, yet macropore volume share is merely 76%, coordination numbers drop to 0.02–0.03, and connectivity is minimal. Mineralogical analysis reveals that quartz content exhibits a positive correlation with reservoir properties, as its rigid grain framework effectively resists compaction. Illite content rises with increasing burial depth, and plastic illite occupies pores and segment throats, resulting in Type C reservoir permeability reduction to 0.01~0.25 mD. Dissolution intensity (Type A > Type B > Type C) and cementation types (quartz cementation prevailing in Type B, illite cementation prevailing in Type C) represent crucial factors governing reservoir quality differentiation. This research confirms the reliability of digital core technology for tight reservoir classification and assessment, developing a discrimination model founded on “pore structure-mineral composition-diagenesis”. It provides a geological basis for sweet spot prediction and efficient development in the study area. Full article

The exploration potential, storage capacity, and exploitability of the deep shale-gas reservoirs are governed by various characteristics of their pore networks. Conventional methods cannot fully capture these features across scales, highlighting the need for an integrated, multi-technique approach. In this study, pore structure and connectivity of the Wufeng–Longmaxi Formation (Luzhou Block) were investigated using Scanning Electron Microscopy (SEM) with the Mosaic Acquisition and Positioning System (MAPS), ImageJ (ImageJ 2.14.0)-based pore analysis, Mercury Intrusion Porosimetry (MIP), and Nuclear Magnetic Resonance (NMR). Based on the samples from eight reservoir layers of Wufeng-WF and Longmaxi-LM1₁^1–7, shale pore connectivity was classified into three grades. Grade A layers, with connected pore volumes above 0.0067 cm³/g and porosity exceeding 1.75%, showed trimodal NMR pore-size distributions and strong connectivity among micro, meso, and macropores. Grade B layers exhibited bimodal pore distributions, moderate pore connectivity (0.0057–0.0067 cm³/g; 1.55–1.75% porosity), and sponge-like organic pores with isolated mineral pores. Grade C layers, with connected pore volumes below 0.0057 cm³/g, showed poor connectivity and unimodal NMR responses. Connected pores (1–100 nm) contributed 20–35% of total pore volume, reflecting the strong heterogeneity of the formation. Interconnected inorganic mineral-hosted pores were found to link locally connected organic pores, forming continuous pore networks. The qualitative and quantitative identification of the pore connectivity of shale reservoirs with MAPS, MIP, and NMR approach provides a robust framework for evaluating shale pore connectivity and identifying high-quality reservoir targets. Full article

Filling mining offers significant technical advantages in controlling rock mass movement and preventing disasters. Investigating the correlation between the macro- and micro-scale characteristics of filling materials will help optimize this process. The paper analyzes the variation patterns and mechanisms of the pore structure and mechanical strength characteristics of the filling body based on low-field nuclear magnetic resonance (NMR) technology and fractal theory, exploring the relationship between microstructure and macroscopic features. Results indicate that as the cement-to-sand ratio or mass concentration decreases, the total pore structure count in the filling material increases, predominantly consisting of micropores that account for over 76%. The complexity of total pores, micropores, mesopores, and macropores progressively decreases. Mechanical strength exhibits a positive correlation with both the cement-to-sand ratio and mass concentration. A reduced cement-to-sand ratio diminishes hydration products, lowering the cohesive strength of tailings particles. As mass concentration increases, the internal structure of the filling body becomes denser, enhancing its mechanical properties. An increase in pore number progressively improves pore connectivity, reducing fluid flow resistance. The porosity of the pore structure exhibits a strong correlation with fractal dimension, mechanical strength, and permeability coefficient, with a coefficient of determination ranging from 0.631 to 0.996. The strength prediction model constructed using mesopore porosity and material intrinsic characteristics also demonstrated excellent accuracy. Full article

The purpose of this study was to evaluate how a multi-component soil conditioner consisting of zeolite, calcium carbonate, potassium humate, and Ascophyllum nodosum extract affects selected soil properties (physical, chemical, and water-related properties, as well as microbial and enzymatic properties) and the growth and grain yield of spring barley (Hordeum vulgare L.). To achieve the goal, one-year research experiments were conducted at three conventionally tilled sites, which were situated on farms across three geographically separate regions in the Kuyavian–Pomeranian Region of Midwestern Poland. Most of the chemical properties, namely, total organic C, total N, pH in KCl, cation exchangeable capacity (CEC), as well as exchangeable (Mg, Ca, K, and Na) and available (Mg, K, and P) forms of nutrients, were not significantly affected by the conditioner or sampling time. Independent of the study location, the percentage of macropores in total porosity (TP) and dissolved nitrogen content (DNt) determined in July were considerably greater in the soil treated with Solactiv compared to the reference soil. Bulk density (BD), in turn, showed the opposite tendency, also suggesting the positive effect of the studied conditioner. At all study sites, application of the conditioner significantly reduced the percentage of micropores in total porosity (TP) (by 17%), while significantly increasing the content of macropores in TP (15%) and enhancing the percentage of available and readily available water capacity (8.5% and 14%). No clear changes in the results of C and N form and enzymatic activity were noted. The activities of DHA and FDAH behave differently in each study site, making it difficult to draw clear conclusions. The cellulase was the only enzyme that was significantly and positively affected by Solactiv at all study sites and for both sampling times. The values of dry matter of roots and plants, barley root length and surface, and barley grain yield were considerably greater in soil amended with Solactiv compared to the reference soil. Because some important soil and plant properties showed a positive response toward the tested conditioner, despite the low dose used, further studies should be conducted at a larger scale, focusing on different soils and plants. Full article

An integrated analysis including total organic carbon (TOC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and gas adsorption experiments was conducted on core samples from the deep Wufeng–Longmaxi (WF-LMX) Formation in the Zigong area to characterize its lithofacies and reservoir characteristics and their influencing factors. The results suggest that eight distinct lithofacies are distinguished and argillaceous/calcareous mixed siliceous shale lithofacies (S-1) is the most optimal lithofacies. The pore surface fractal dimension (D) was derived by applying the Frenkel–Halsey–Hil (FHH) model to low-temperature N₂ adsorption (LTNA) data. The meso-macropore regime shows higher heterogeneity than the micropore regime (since D₂ > D₁). Both D₁ and D₂ show a significant positive relation with TOC and carbonate content, a slight negative correlation with quartz content, and no clear link with clay content. In the initial depositional stage of the LMX Formation, a low-energy, stagnant, and strongly reducing environment facilitated the accumulation of siliceous biogenic sediments, leading to the formation of siliceous shale characterized by high paleoproductivity. In the middle to late stages of LMX Formation deposition, increased input of terrigenous clastic material, shallower water depths, and the gradual disruption of the anoxic conditions resulted in diminished paleoproductivity, causing a transition from siliceous shale to a mixed shale lithofacies. Increased TOC and carbonate content enhance pore heterogeneity, with TOC predominantly influencing micropores and carbonates controlling macropores. In contrast, higher quartz content inhibits pore development. Full article

Camellia oleifera Abel shell is an abundant lignocellulosic byproduct of the Chinese woody oil industry, which is currently underutilized. To achieve its high-value utilization, this study developed an innovative cascade process integrating ultrasound-assisted extraction and macroporous resin purification for the efficient preparation of purified polyphenols from the shell (P-CPCS). The major constituents were identified by quadrupole/Orbitrap high-resolution mass spectrometry (HPLC-Q-Exactive-MS: Biotech Pack Co., Ltd., Beijing, China) analysis. The optimized process significantly enhanced the polyphenol yield (40.05 ± 0.58 mg GAE/g dw) and purity (57.72%), surpassing conventional methods. P-CPCS exhibited exceptional multifunctional bioactivities, including potent antioxidant capacity (with low IC₅₀ values against DPPH, ABTS⁺·, and ·OH radicals), effective tyrosinase inhibition (whitening effect), and significant bacteriostatic effects against various pathogens. Furthermore, P-CPCS notably suppressed the LPS-induced inflammatory response in RAW264.7 macrophages by reducing NO overproduction. This work highlights a novel and efficient strategy for upcycling agricultural waste into a high-performance natural antioxidant, positioning P-CPCS as a promising ingredient for applications in functional foods, cosmetics, and biomaterial stabilization. Full article

Understanding the shear behavior of loess–concrete interfaces is essential for foundation design in collapsible loess regions, yet the pore-scale mechanisms remain unclear. This study investigates the relationship between interface shear strength and loess microstructure at different burial depths. Direct shear tests were conducted on undisturbed loess samples under stress conditions simulating in situ confinement. High-resolution SEM images were analyzed via Avizo to quantify pore area ratios at multiple scales, fractal dimensions, and directional probability entropy. Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA) were employed to statistically interpret the microstructure–mechanics relationship. Results show that interface shear strength increases significantly with depth (35.2–258.4 kPa), primarily due to reduced total porosity and macropore content, increased small and micropore fractions, and enhanced isotropy of pore orientation. Fractal dimension negatively correlates with strength, indicating that compaction-induced boundary regularization enhances particle contact and shear resistance, while entropy positively correlates with strength, reflecting structural homogenization and isotropic pore orientation. PCA and HCA further confirm that small and micropores are the dominant contributors to interface resistance. This study provides a quantitative framework linking microstructural evolution to mechanical performance, offering new insights for optimizing pile–soil interface design in loess areas. Full article

The nanoporous structure of coal is crucial for the occurrence and development of coalbed methane (CBM). This study, leveraging the combined characterization of atomic force microscopy (AFM) and Gwyddion software (v2.62), investigated six anthracite samples with varying degrees of metamorphism (R_o = 2.11–3.36%). It revealed the intrinsic relationships between their nanoporous structures, surface morphologies, fractal characteristics, and coalification processes. The research found that as R_o increases, the surface relief of coal decreases significantly, with pore structures evolving from being macropore-dominated to micropore-enriched, and the surface tending towards smoothness. Surface roughness parameters (R_a, R_q) exhibit a negative correlation with R_o. Quantitative data indicate that area porosity, pore count, and shape factor positively correlate with metamorphic grade, while mean pore diameter negatively correlates with it. The fractal dimensions calculated using the variance partition method, cube-counting method, triangular prism measurement method, and power spectrum method all show nonlinear correlations with R_o, moisture (M_ad), ash content (A_ad), and volatile matter (V_daf). Among these, the fractal dimension obtained by the triangular prism measurement method has the highest correlation with R_o, A_ad, and V_daf, while the variance partition method shows the highest correlation with M_ad. This study clarifies the regulatory mechanisms of coalification on the evolution of nanoporous structures and surface properties, providing a crucial theoretical foundation for the precise evaluation and efficient exploitation strategies of CBM reservoirs. Full article

Large soil pores critically influence water and solute transport in soils. The presence of preferential flow paths created by soil macropores can profoundly impact water quality, underscoring the necessity of accurately assessing the characteristics of these macropores. However, it remains unclear whether variations in macropore structure exist between different altitudes and positions of terraced paddy fields. The primary objective of this research was to utilize X-ray computed tomography (CT) and image analysis techniques to characterize the soil pore structure at both the inner field and ridge positions across different altitude levels (high, medium, and low altitude) within terraced paddy fields. The results indicate that there are significant differences in the distribution of large soil pores at different altitudes, with large pores concentrated in the surface layer (0–10 cm) in low-altitude areas, while in high-altitude areas, the distribution of large pores is more uniform. Additionally, as altitude increases, the porosity of large pores shows an increasing trend. The three-dimensional equivalent diameter and large pore volume are primarily characterized by large pores ranging from 1 to 2 mm and 0 to 5 mm³, respectively, with their morphology predominantly appearing spherical or ellipsoidal. The connectivity of large pores in the surface layer of paddy soil is stronger than that in the bunds. However, this connectivity gradually weakens with increasing soil depth. The findings from this study provide valuable quantitative insights into the unique characteristics of soil macropores that vary according to the altitude and position in terraced paddy fields. Moreover, this study emphasizes the necessity for future research that encompasses a broader range of soil types, altitudes, and terraced paddy locations to validate and further explore the identified relationships between altitude and macropore characteristics. Full article

The development of deep coalbed methane (buried depth > 2000 m) in the Yan’an block of Ordos Basin is limited by low permeability, the pore structure of the coal reservoir, and the gas–water occurrence relationship. It is urgent to clarify the key control mechanism of pore structure on gas migration. In this study, based on high-pressure mercury intrusion (pore size > 50 nm), low-temperature N₂/CO₂ adsorption (0.38–50 nm), low-field nuclear magnetic resonance technology, fractal theory and Pearson correlation coefficient analysis, quantitative characterization of multi-scale pore–fluid system was carried out. The results show that the multi-scale pore network in the study area jointly regulates the occurrence and migration process of deep coalbed methane in Yan’an through the ternary hierarchical gas control mechanism of ‘micropore adsorption dominant, mesopore diffusion connection and macroporous seepage bottleneck’. The fractal dimensions of micropores and seepage are between 2.17–2.29 and 2.46–2.58, respectively. The shape of micropores is relatively regular, the complexity of micropore structure is low, and the confined space is mainly slit-like or ink bottle-like. The pore-throat network structure is relatively homogeneous, the difference in pore throat size is reduced, and the seepage pore shape is simple. The bimodal structure of low-field nuclear magnetic resonance shows that the bound fluid is related to the development of micropores, and the fluid mobility mainly depends on the seepage pores. Pearson’s correlation coefficient showed that the specific surface area of micropores was strongly positively correlated with methane adsorption capacity, and the nanoscale pore-size dominated gas occurrence through van der Waals force physical adsorption. The specific surface area of mesopores is significantly positively correlated with the tortuosity. The roughness and branch structure of the inner surface of the channel lead to the extension of the migration path and the inhibition of methane diffusion efficiency. Seepage porosity is linearly correlated with gas permeability, and the scale of connected seepage pores dominates the seepage capacity of reservoirs. This study reveals the pore structure and ternary grading synergistic gas control mechanism of deep coal reservoirs in the Yan’an Block, which provides a theoretical basis for the development of deep coalbed methane. Full article