Search Results (298)

Shallow gas reservoirs exhibit low formation pressure and gas injection levels, leading to low-resistivity contrast between gas-bearing reservoirs and fully water-saturated layers. Gas-bearing formation identification and water saturation estimation face great challenges. To improve the accuracy of shallow gas reservoir identification and logging evaluation, it is essential to analyze the genesis mechanisms underlying the low-resistivity contrast. This study used the HJ Formation, a typical shallow gas reservoir located in the BY Sag of the eastern South China Sea Basin as an example. Combining the results of nuclear magnetic resonance (NMR), full rock mineral analysis and X-ray diffraction of clay minerals in the laboratory, it was determined that the genesis mechanism for the low-resistivity contrast in the gas-bearing reservoir was due to the high irreducible water saturation (S_wi) and the cation-induced supplementary conductivity. Afterwards, we integrated three methods, density–neutron correlation, calculation of the apparent formation water resistivity, and cross-plots of conventional and gas-logging curves, to identify shallow gas reservoirs. In addition, we also established a Waxman–Smits-based model to estimate water saturation. Compared with the typical Archie’s equation, the predicted water saturation curve using the Waxman–Smits-based model was more reasonable. The established methods and models can be used in target shallow gas reservoir evaluations, and it also has reference value for other types of oilfields with similar physical characteristics. Full article

Waterflooding, a key method for secondary hydrocarbon recovery, has been employed since the early 20th century. Over time, the role of water chemistry and ions in recovery has been studied extensively. Low-salinity water (LSW) injection, a common technique since the 1930s, improves oil recovery by altering the wettability of reservoir rocks and reducing residual oil saturation. Recent developments emphasize the integration of LSW with various recovery methods such as CO₂ injections, surfactants, alkali, polymers, and nanoparticles (NPs). This article offers a comprehensive perspective on how LSW injection is combined with these enhanced oil recovery (EOR) techniques, with a focus on improving oil displacement and recovery efficiency. Surfactants enhance the effectiveness of LSW by lowering interfacial tension (IFT) and improving wettability, while ASP flooding helps reduce surfactant loss and promotes in situ soap formation. Polymer injections boost oil recovery by increasing fluid viscosity and improving sweep efficiency. Nevertheless, challenges such as fine migration and unstable flow persist, requiring additional optimization. The combination of LSW with nanoparticles has shown potential in modifying wettability, adjusting viscosity, and stabilizing emulsions through careful concentration management to prevent or reduce formation damage. Finally, building on discussions around the underlying mechanisms involved in improved oil recovery and the challenges associated with each approach, this article highlights their prospects for future research and field implementation. By combining LSW with advanced EOR techniques, the oil industry can improve recovery efficiency while addressing both environmental and operational challenges. Full article

The development of overstory vegetation can considerably influence the composition and dynamics of herbaceous layer vegetation. However, the type of ecological processes underlying these changes remain poorly understood. We aimed to analyze changes in herbaceous layer species composition in Quercus mongolica Fisch. ex Ledeb. forests in central South Korea and identify the ecological processes driving succession, using zeta diversity and species turnover. We also sought to address regional bias in existing long-term monitoring data. Permanent 1 ha survey plots were established according to International Long Term Ecological Research Network guidelines, divided into 100 subplots. Data on species composition, crown openness, transmitted light, and structural variables were collected through four surveys (2014, 2015, 2017, and 2020) between 2014 and 2020. Zeta diversity and turnover metrics were used to evaluate succession dynamics. Species richness, cover, and turnover in the herbaceous layer were significantly correlated with overstory structure and rock cover. Crown openness and transmitted light declined but did not correlate with species turnover. Zeta diversity shifted from a power function model (2014–2017) to an exponential model (2020), indicating a shift from deterministic to stochastic processes. Successional changes in herbaceous vegetation may indicate a potential shift in forest structure in Q. mongolica stands—from stable, deterministic patterns to more variable, stochastic processes—highlighting the need for long-term monitoring in dynamic forest ecosystems. Full article

Spatially intersecting roadways in mines are prone to stress concentration due to disturbances during mining operations, which significantly affects the stability of the inter-roadway surrounding rock between the roadways. Analyzing the stability of underlying roadways under the influence of disturbances from overlying roadways, as well as enhancing the stability of the inter-roadway surrounding rock, is critical for ensuring safe and efficient mining operations. Based on the geological conditions at the spatial intersection of the 5⁻¹ Coal Auxiliary Transportation Roadway and the 5⁻² Coal Auxiliary Transportation Roadway in the Hengliao Coal Mine, this study investigates the deformation and failure characteristics of the surrounding rock between roadways under dynamic loading. A stability criterion equation for the inter-roadway surrounding rock is established using the limit equilibrium method. Furthermore, numerical simulations are conducted to analyze the stress–strain distribution in the surrounding rock and supporting structures at the intersection area of the 5⁻¹ roadway under the dynamic loading conditions induced by trackless rubber-tired vehicle operation in the 5⁻² roadway. Field applications demonstrate that the proposed combined support scheme effectively controls roadway deformation and ensures the stability of the rock mass between roadways. This study provides valuable insights for stability assessment and support design of spatially intersecting roadways. Full article

The geological structural complexity and microscale heterogeneity of shale reservoirs, characterized by the brittleness index and natural fracture density, exert a decisive effect on hydraulic fracturing’s effectiveness. However, the mechanisms underlying the true microscale heterogeneity of shale structures, which is neglected in conventional models and influences fracture evolution, remain unclear. Here, high-resolution scanning electron microscopy (SEM) was employed to obtain realistic distributions of mineral components and natural fractures, and hydraulic–mechanical coupled simulation models were developed within the Realistic Failure Process Analysis (RFPA) simulator using digital rock techniques. The analysis examined how the brittleness index and natural fracture density affect the fracture morphology’s complexity, mineral failure behavior, and flow conductivity. Numerical simulations show that the main fractures preferentially propagate toward areas with high local brittleness and dense natural fractures. Both the fracture’s fractal dimension and the stimulated reservoir volume increased with the brittleness index. A moderate natural fracture density promotes the fracture network’s complexity, whereas excessive densities may suppress the main fracture’s propagation. Microscopically, organic matter and silicate minerals are more prone to damage, predominantly tensile failures under external loading. These findings highlight the dominant role of microscale heterogeneity in shale fracturing and provide theoretical support for fracture control and stimulation optimization in complex reservoirs. Full article

Close-distance coal seam mining in Danhou coal mine has caused serious deformation in the underlying soft rock roadways. The mechanism of this type of deformation is explored through theoretical analysis and numerical simulation, and corresponding control measures are proposed. Firstly, the mechanical model of abutment stress transfer along the underlying rock stratum is established, and the analytical solution of abutment stress at any point of the underlying rock stratum is derived. Secondly, the impact of upper working face mining on the underlying soft rock roadway is investigated through numerical simulation. Subsequently, the stress distribution characteristics of the surrounding rock of the rectangular roadway and straight- wall arch roadway are compared and analyzed. Finally, a support scheme for the underlying soft rock roadway is presented and implemented in engineering practice. Field engineering application results demonstrate that, after the combined support of high-strength bolts and grouting, the average deformation on both sides of the roadway is reduced by 63.4%, and the average floor heave is decreased by 93%. This indicates that the technology effectively controls the deformation of the surrounding rock in soft rock roadways during close-distance coal seam mining. Full article

The Qinghai–Tibet Plateau presents a unique challenge for infrastructure development due to its extreme geological and climatic conditions—high elevation, large diurnal temperature fluctuations, frequent freeze–thaw cycles, intense ultraviolet radiation, and seasonal precipitation. These factors greatly accelerate the weathering of rock materials, leading to aggregates with increased porosity, microcracking, and weakened mechanical properties. While the engineering implications of such degradation are evident, the underlying material science of weathered aggregates—particularly their microstructure–property relationships—remains insufficiently explored, necessitating further investigation to inform material selection and design. In this study, three representative types of weathered aggregates (silica-rich, carbonaceous, and alumina-rich), alongside unweathered natural aggregates, were examined through both macro-scale (density, water absorption, crushing value, abrasion resistance) and micro-scale (scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS)) analyses. To capture the material evolution, we introduced a simplified classification framework based on the Si/Al ratio and porosity and applied a gray entropy correlation model to quantify the coupling between microstructure and mechanical performance. Results show that weathering reduces the Si/Al ratio from 2.45 to 1.82, increases porosity from 4.2% to 12.7%, enlarges the average pore size to 0.85 μm, raises microcrack density to 1.40 μm/μm², and increases the proportion of connected pores to 68.2%. These microstructural degradations correlate with decreased aggregate density, increased water absorption (up to 8.0%), higher crushing value (27.4%), and abrasion resistance loss (26.0%). Based on these findings, a weathered aggregate classification and pretreatment strategy is proposed, offering a practical reference for engineers to improve material performance in high-altitude road construction. Full article

Background: Genome-wide association studies (GWAS) have been extensively employed to elucidate the genetic architecture of body weight (BW) traits in chickens, which represent key economic indicators in broiler production. With the growing availability of genomic data from diverse commercial and resource chicken populations, a critical challenge lies in how to effectively integrate these datasets to enhance sample size and thereby improve the statistical power for detecting genetic variants associated with complex traits. Methods: In this study, we performed a multi-population GWAS meta-analysis on BW traits across three genetically distinct chicken populations, focusing on BW at 56, 70, and 84 days of age: P1 (N301 Yellow Plumage Dwarf Chicken Line; n = 426), P2 (F2 reciprocal cross: High Quality Line A × Huiyang Bearded chicken; n = 494), and P3 (F2 cross: Black-bone chicken × White Plymouth Rock; n = 223). Results: Compared to single-population GWAS, our meta-analysis identified 77 novel independent variants significantly associated with BW traits, while gene-based association analysis implicated 59 relevant candidate genes. Functional annotation of BW56- and BW84-associated SNPs (single-nucleotide polymorphisms) 1_170526144G>T and 1_170642110A>G, integrated with tissue-specific regulatory annotations, revealed significant enrichment of enhancer and promoter elements for KPNA3 and CAB39L in muscle, adipose, and intestinal tissues. Through this meta-analysis and integrative genomics approach, we identified novel candidate genes associated with body weight traits in chickens. Conclusions: These findings provide valuable mechanistic insights into the genetic mechanisms underlying body weight regulation in poultry and offer important references for selective breeding strategies aimed at improving production efficiency in the poultry industry. Full article

Rock creep, a key factor in the long-term stability of deep geotechnical engineering, remains challenging to study due to the complexity of its microscopic damage mechanisms. Laboratory creep tests are limited by long durations and scale effects, while phenomenological models cannot fully capture the underlying processes. This study employs the parallel-bonded stress corrosion (PSC) model in PFC2D to simulate sandy mudstone’s creep behavior, systematically correlating macroscopic creep deformation with microscopic damage evolution and energy conversion. The model reproduces the four stages of the idealized creep curve and quantifies the effects of axial stress level and confining pressure on creep lifetime, rate, and failure mode. Increasing axial stress shortens creep lifetime; every 10% increase raises the creep rate by a factor of 4–14, and high stress enhances nonlinear deformation, producing stair-stepping curves due to unstable microcrack propagation. In contrast, confining pressure prolongs lifetime; at 90% uniaxial compressive strength (UCS), 15 MPa extends it from 2.78 h to ~25 years. Confinement also enhances ductility by suppressing tensile stresses and delaying damage accumulation. This study reveals the coupling mechanism of stress-corrosion-induced subcritical crack propagation and energy dissipation, clarifies the microscopic origin of stepped creep curves, and provides a micromechanical framework for long-term stability evaluation in deep geotechnical engineering. Full article

Underground blasting vibrations are a critical factor influencing the stability of mine slopes. However, existing studies have yet to establish a quantitative relationship or clarify the underlying mechanisms linking blasting-induced vibrations and slope deformation. Taking the Shilu Iron Mine as a case study, this research develops a dynamic mechanical response model of slope stability that accounts for blasting loads. By integrating slope radar remote sensing data and applying the Pearson correlation coefficient, this study quantitatively evaluates—for the first time—the correlation between underground blasting activity and slope surface deformation. The results reveal that blasting vibrations are characterized by typical short-duration, high-amplitude pulse patterns, with horizontal shear stress identified as the primary trigger for slope shear failure. Both elevation and lithological conditions significantly influence the intensity of vibration responses: high-elevation areas and structurally loose rock masses exhibit greater dynamic sensitivity. A pronounced lag effect in slope deformation was observed following blasting, with cumulative displacements increasing by 10.13% and 34.06% at one and six hours post-blasting, respectively, showing a progressive intensification over time. Mechanistically, the impact of blasting on slope stability operates through three interrelated processes: abrupt perturbations in the stress environment, stress redistribution due to rock mass deformation, and the long-term accumulation of fatigue-induced damage. This integrated approach provides new insights into slope behavior under blasting disturbances and offers valuable guidance for slope stability assessment and hazard mitigation. Full article

The layering of the lower layered kakortokite in the per-alkaline Ilímaussaq complex has been interpreted as an orthocumulus rock. Petrographic observation and mineral chemical data from the topmost and the lowest part of the layered kakortokite show signs that indicate massive metasomatic overprint. The occurrence of globular structures in the top part of kakortokite and fine-grained inclusions in the lower layered kakortokite are interpreted as the precursor of kakortokite and the result of a subsolidus reaction between a fluid phase and the underlying rock, respectively. Two different processes led to the formation of kakortokite, a precursor where a clear repetitive layering occurs and a chemical reaction between a fluid phase and the underlying rock where different kakortokite types are randomly interstratified. Both metasomatic events led to a higher rare earth element (REE) grade of the original REE mineralization. Full article

The Mazenod Lake region of the southern Great Bear Magmatic Zone (GBMZ) of the Northwest Territories, Canada, comprises the north-central portion of the Faber volcano-plutonic belt. Widespread and abundant surface exposure of several coalescing hydrothermal systems enables this paper to document, without ambiguity, the relationships between geology, structure, alteration, and mineralization in this well exposed iron-oxide–copper–gold (IOCG) mineral system. Mazenod geology comprises rhyodacite to basaltic-andesite ignimbrite sheets with interlayered volcaniclastic sedimentary rocks dominated by fine-grained laminated tuff sequences. Much of the intermediate to mafic nature of volcanic rocks is masked by low-intensity but pervasive metasomatism. The region is affected by a series of coalescing magmatic–hydrothermal systems that host the Sue–Dianne magnetite–hematite IOCG deposit and several related showings including magnetite, skarn, and iron oxide apatite (IOA) styles of alteration ± mineralization. The mid to upper levels of these systems are exposed at surface, with underlying batholith, pluton and stocks exposed along the periphery, as well as locally within volcanic rocks associated with more intense alteration and mineralization. Widespread alteration includes potassic and sodic metasomatism, and silicification with structurally controlled giant quartz complexes. Localized tourmaline, skarn, magnetite–actinolite, and iron-oxide alteration occur within structural breccias, and where most intense formed the Sue–Dianne Cu-Ag-Au diatreme-like breccia deposit. Magmatism, volcanism, hydrothermal alteration, and mineralization formed during a negative tectonic inversion within the Wopmay Orogen. This generated a series of oblique offset rifted basins with continental style arc magmatism and extensional structures unique to GBMZ rifting. All significant hydrothermal centers in the Mazenod region occur along and at the intersections of crustal faults either unique to or put under tension during the GBMZ inversion. Full article

The Nanmiao Emergency Groundwater Source Area, rich in H₂SiO₃, serves as a strategic freshwater reserve zone in western Jiangxi Province. However, the mechanisms underlying groundwater formation in this area remain unclear. This study applied a combination of statistical analysis, isotopic tracing, and hydrochemical modeling to reveal the hydrochemical characteristics and origins of groundwater in the region. The results indicate that Na⁺ and Ca²⁺ dominate the cations, while HCO₃⁻ and Cl⁻ dominate the anions. Groundwater from descending springs is characterized by low mineralization and weak acidity, with hydrochemical types of primarily HCO₃–Na·Mg and HCO₃–Mg·Na·Ca. Groundwater from boreholes is weakly mineralized and neutral, with dominant hydrochemical types of HCO₃–Ca·Na and HCO₃–Ca·Na·Mg, suggesting a deep circulation hydrogeochemical process. Hydrogen and oxygen isotope analysis indicates that atmospheric precipitation is the primary recharge source. The chemical composition of groundwater is mainly controlled by rock weathering, silicate mineral dissolution, and cation exchange processes. During groundwater flowing, water and rock interactions, such as leaching, cation exchange, and mixing, occur. This study identifies the recharge sources and circulation mechanisms of regional groundwater, offering valuable insights for the sustainable development and protection of the emergency water source area. Full article

Authenticity is a core principle in conservation guidelines and a key goal of heritage preservation, especially in Serbia, where many aging objects face ongoing deterioration. The subject of this study is the church within the Blagoveštenje Monastery complex in the Ovčar-Kablar gorge, built using stone from a local quarry at the beginning of the 17th century. The inclination of the structure, observed as progressively increasing over the centuries, raises important concerns regarding its stability. This research focuses on identifying the underlying causes of this phenomenon in order to support its long-term preservation. The methods used the study are long-term in situ observations including analysis, geodetic research, 3D laser imaging, geophysical, geological, archaeological research, evaluation of current condition, determination of structural failures and their cause and monitoring the structural behavior of elements. All methods were carried out in accordance with the definition of rehabilitation measures and the protection of masonry buildings. The main contribution of this study is identifying that the church’s inclination and deviation result from the northern foundation resting on weaker soil and a deeper rock mass compared to the southern side. The research approach and findings presented in this paper can serve as a guide for future endeavors aimed at identifying the causes of deformations and the restoration and structural rehabilitation of masonry buildings as cultural heritage. Full article

In recent years, major breakthroughs have been achieved in oil and gas exploration within China’s complex thrust–fault zones in the western region, confirming their significant potential. The northern piedmont zone of the Turpan–Hami Basin, a classic thrust–fold belt formed by the Bogda Orogenic belt’s overthrusting, has seen the discovery of several Jurassic–Cretaceous hydrocarbon fields, yet exploration at its thrust-front margins remains relatively underdeveloped. This study focuses on the central piedmont segment at Qialekan and Kekeya, integrating 3D seismic data with fault-related folding theory and balanced cross-section restoration to systematically analyze the area’s tectonic evolution. We specifically examine the formation and modification of wedge structures and assess their petroleum geological significance. Our results indicate that the wedge bodies formed in the Late Jurassic, along with their subsequent basinward insertion, critically controlled the present-day structural framework. In the Qialekan area, wedge formation coincided with the main hydrocarbon expulsion phase of underlying Permian source rocks. Type I faults acted as effective migration pathways, while later tectonic reworking was limited, favoring for hydrocarbon preservation. In contrast, in the Kekeya area, wedge structures underwent intense modification by Type II faults, which pierced the wedge and facilitated vertical hydrocarbon migration, creating a mixed-source accumulation pattern. The findings of this study provide new theoretical insights and practical guidance for future exploration in the northern piedmont zone and also offer a valuable reference for hydrocarbon exploration in structurally similar foreland basins. Full article