Search Results (919)

The multi-cycle high-rate injection and production operations in Underground Gas Storage (UGS) facilities converted from depleted fracture-pore carbonate gas reservoirs induce complex rock–fluid interactions that threaten long-term integrity and performance. This study experimentally investigates the petrophysical responses of the Xiangguosi (XGS) UGS carbonate reservoirs in China using multi-cycle stress sensitivity tests, fines migration experiments, and water evaporation–salt precipitation analyses. SEM observations distinguish the contributions of crack closure and matrix compression to permeability evolution. Results show a sharp contrast in mechanical damage: high-quality rocks present negligible permanent deformation (<8% Young’s modulus reduction), whereas poor-quality rocks suffer catastrophic deterioration (>60%). Fines migration exhibits a three-stage behavior under cyclic flow, with water saturation significantly aggravating permeability impairment. A critical salinity threshold (220,000 ppm) is identified for the transition between drying-enhanced storage and salt plugging. Permeability declines sharply despite a slight porosity increase due to selective salt clogging of key pore throats, revealing a clear porosity–permeability decoupling. Salt deposition under movable water conditions can reduce UGS capacity by up to 1.45%. Reservoir heterogeneity, microfractures, karst structures, and initial petrophysical properties dominate the storage and flow space evolution. This work provides a predictive framework for optimizing injection–production strategies and improving the performance of complex carbonate UGS. Full article

Molten salt electrodeposition is a promising technique to prepare high-performance tungsten coatings for fusion reactor first-wall components. However, the ultra-high temperature during deposition causes severe grain coarsening and precipitate dissolution in CuCrZr alloy substrates, resulting in dramatic mechanical property degradation. In this study, a thermal cycle at 1223.15 K for 100 h was employed to simulate the thermal impact of molten salt tungsten electrodeposition (MSE) on CuCrZr alloys, and an aging treatment (703.15 K for 12 h) was adopted to restore the degraded mechanical properties. After aging, the tensile strength and yield strength recovered to 378.35 ± 7.40 MPa and 261.02 ± 3.40 MPa, meeting the minimum tensile property requirements of ITER for CuCrZr alloys. The recovery is attributed to nano-sized Cr-rich phase precipitation and high-density dislocations, providing effective Orowan precipitation strengthening. This work provides the first simple, engineering-friendly post-treatment to repair performance degradation of CuCrZr under the extreme thermal exposure of molten salt electrodeposition, which is critical for large-scale fabrication of high-performance plasma-facing components (PFCs) for fusion reactors. Full article

Two types of coatings, NiCrAlY and NiCrAlY/YSZ, were fabricated on the surface of M247 alloy by the atmospheric plasma spraying (APS) technique. Under pure Na₂SO₄ and 25 wt.% NaCl-containing mixed salt deposits at 900 °C in air, the M247 alloy underwent rapid catastrophic corrosion. The non-protective corrosion products formed on the surface included NiO and (Ni,Co)Cr₂O₄ spinel. The hot corrosion of M247 under the pure Na₂SO₄ salt deposit followed a basic fluxing mechanism, whereas under the NaCl-containing mixed salt deposit, it was dominated by an active oxidation mechanism. During hot corrosion, the NiCrAlY coating developed a continuous, dense, and highly protective α-Al₂O₃ oxide scale on its surface, endowing it with superior hot corrosion resistance. The thermal barrier coating of NiCrAlY/YSZ exhibited the best hot corrosion resistance, attributed to the physical barrier and thermal barrier effects of the outer YSZ ceramic layer. Full article

Inorganic scale formation in oil wells is a major flow assurance challenge, causing production losses, increased intervention costs and reduced operational efficiency. In Brazil, recent discoveries in pre-salt reservoirs have increased the relevance of calcium carbonate (CaCO${}_3$) scaling under high-pressure and high-temperature (HPHT) conditions. Experimental data representative of petroleum environments under such conditions, particularly regarding the influence of CO${}_2$ and flow conditions, remain limited. In this study, a compact pressurized experimental unit was designed and constructed to investigate the dynamic formation, deposition and adhesion of CaCO${}_3$ under conditions close to those encountered in oil production systems. A dedicated experimental methodology was developed to promote controlled mixing of aqueous sodium bicarbonate (NaHCO${}_3$) and calcium chloride (CaCl${}_2$) solutions and CO${}_2$ injection, enabling precise control of pressure, temperature and flow regime. The effects of turbulent flow, expressed by different Reynolds numbers, on the deposited CaCO${}_3$ mass and its adhesion to the substrate were systematically evaluated under controlled conditions of 40 °C and a pressure drop of 15 bar was imposed in the control valve in order to promote the flash of CO${}_2$ and CaCO${}_3$ precipitation. Complementary characterization analyses were performed to assess crystal morphology and adhesion detachment strength. The results provide new experimental insights into CaCO${}_3$ scaling mechanisms under CO${}_2$-rich flowing conditions, contributing to improved understanding of scale adhesion and the development of mitigation strategies for flow assurance in oil and gas operations. Full article

Redox-flow batteries are a promising emerging technology for large-scale storage of renewable energy. However, existing ion-exchange membranes used for separating electrolytes are expensive and often ineffective at preventing crossover of redox-active species, leading to a decrease in battery capacity over time. Herein, we introduce a new class of proton-conducting membranes formed by depositing highly alkylated waxy hydrophobic salts on porous polypropylene supports and demonstrate that they form self-assembled nanostructures which exclusively conduct protons via a unique mechanism of action. These new “ionowax” membranes display comparable proton conductivities to existing commercially available functionalized porous polymer membranes but are cheaper and easier to fabricate. We anticipate that these new membranes will facilitate future development of cheaper and/or longer-lasting aqueous redox-flow batteries. Full article

Nephrocalcinosis, defined as the deposition of calcium salts within the renal parenchyma, represents a radiologic and pathologic endpoint shared by a broad spectrum of metabolic and monogenic disorders. Advances in genomic medicine have identified more than 30 genes involved in tubular transport, mineral and acid–base homeostasis, oxalate metabolism, mitochondrial function, ciliary signaling, and nephron development, reframing nephrocalcinosis as a heterogeneous manifestation of discrete molecular defects rather than a single disease entity. Despite this diversity, these conditions converge on common physicochemical pathways of tubular supersaturation, crystal nucleation, growth, and intrarenal retention. These processes are amplified by the intrinsic vulnerability of the renal medulla—characterized by hyperosmolality, hypoxia, and slow tubular flow—and by epithelial injury, loss of crystallization inhibitors, and impaired ciliary signaling. Distinct genotype–phenotype signatures, including age at onset, biochemical profiles, and extrarenal manifestations, provide important diagnostic clues and help differentiate major monogenic entities. The increasing availability of targeted gene panels, whole-exome sequencing, and whole-genome sequencing has substantially improved diagnostic yield, particularly in pediatric populations. Molecular diagnosis now directly informs therapeutic decision-making and long-term management, enabling a shift toward precision nephrology. This narrative review integrates genetic, mechanistic, and clinical perspectives to illustrate how molecular diagnosis reshapes the evaluation, prognosis, and treatment of nephrocalcinosis. Full article

Inverse scattering problems seek anomalies in a medium given data measured after the interaction with emitted waves. Due to noise, predictions about the nature of these inclusions should be complemented with uncertainty estimates. To this end, we propose a progressive framework for inverse scattering from low- to high-dimensional Bayesian formulations depending on the prior information and the problem complexity. We aim to reduce computational costs by exploiting educated prior information. When we look for a few well-separated inclusions in a known medium with information about their number, we resort to low-dimensional parameterizations in terms of a few random variables representing their shape and material constants. We test this approach detecting anomalies in tissues and deposits in stratified subsoils. In more complex situations where the anomalies may overlap, we propose high-dimensional parameterizations obtained from Karhunen–Loève (KL) or Fourier expansions of the density and velocity fields. We employ these methods to characterize oil and gas reservoirs in a salt dome configuration, where the screening effect of the dome cap prevents the obtention of adequate prior information. We characterize the posterior probability by means of affine invariant ensemble and functional ensemble MCMC samplers depending on dimensionality. This provides information on configurations with the highest a posteriori probability and the uncertainty around them, identifying factors that could reduce the uncertainty. In high-dimensional setups, techniques based on KL developments are more effective and stable. A recurring issue is the choice of the a priori covariance (which strongly affects the results) and the choice of its hyperparameters. Here, we use educated choices. Formulations that include them as additional parameters could be a next step at a higher cost. Full article

Seawater desalination has become a critical approach to mitigating the global scarcity of freshwater resources. This study aims to comprehensively review desalination methods based on thermal and electromagnetic methods, examining their processes, benefits, and limitations. Thermal methods include multi-stage flash distillation, multi-effect distillation, thermal vapor compression, and mechanical vapor compression. These techniques rely on evaporation and distillation to remove salts and are effective in treating highly saline water. However, they consume large amounts of energy and are prone to problems such as limescale and corrosion. In contrast, electromagnetic-based technologies represent a novel, promising approach for enhancing desalination performance. Electromagnetic fields contribute to improved membrane performance and equipment longevity by modulating ionic behavior and mitigating surface fouling. Empirical studies suggest that such interventions can lead to reduced energy usage and lower rates of mineral deposition. The findings reviewed here suggest that integrating thermal and electromagnetic techniques may offer a viable pathway toward more sustainable, efficient, and reduced environmental impacts. Full article

Polyhalite, K₂SO₄•MgSO₄•2CaSO₄•2H₂O, a ternary evaporite mineral, is commonly found in evaporitic rock salt strata, where it acts as an indicator mineral for potash evaporite deposits. As a directly exploitable mineral potash fertilizer, polyhalite serves as an important substitute for potassium resources. The thermodynamic properties of polyhalite remain poorly characterized experimentally; consequently, current estimates predominantly rely on predictive modeling and indirect experimental approaches. The Raman spectra of free SO₄²⁻ vibrational modes in various sulfate minerals are sensitive to the local symmetry and hydrogen-bonding environment within crystal hydrates, and are directly influenced by the surrounding crystal field. This sensitivity makes Raman spectroscopy a powerful tool for investigating and identifying the crystal structures of sulfate minerals. In this work, the thermodynamic and Raman vibrational properties of polyhalite were investigated using density functional theory (DFT). Phonon calculations at the optimized geometry were employed to compute polyhalite’s key thermodynamic properties—specific heat, entropy, enthalpy, Gibbs free energy, and Debye temperature—over a temperature range of 0–1000 K. The results showed that: (1) the computed volume exhibited minimal error, approximately 0.87%, compared to experimental data; (2) the calculated values for the isobaric heat capacity and entropy were 420.72 and 531.39 J·mol⁻¹·K⁻¹ at 298.15 K, respectively; and (3) the calculated value for the free energy of formation at 298.15 K was −5670 kJ·mol⁻¹. The computed Raman spectrum results showed that the typical spectral features of polyhalite are: (1) ν1 for 1024 cm⁻¹, symmetric stretching mode; (2) ν2 for 464 cm⁻¹, symmetry bending mode; and (3) ν4 for 627 cm⁻¹, anti-symmetry bending mode. Full article

The tribocorrosion behavior of AZ31 and WE43 was investigated during sliding wear tests in Hank’s balanced salt solution (HBSS) and pure water. While wear volume increased monotonically with load in air and water, HBSS exhibited a distinct non-monotonic trend; the maximum material loss occurred at the minimum load (0.98 N) and decreased at 2.94 N before rising again. This indicates that at low loads, degradation is primarily driven by accelerated chemical dissolution (tribocorrosion) rather than by purely mechanical abrasion. The magnitude of wear followed the order [HBSS] > [air] > [water] in the low-load range (0.98–1.96 N), whereas it shifted to [air] > [HBSS] > [water] in the high-load range (2.94–5.88 N). A comparison of the wear rate of the alloys shows that the wear rate in HBSS differs from that in water, depending on the hardness of the substrate, similar to conditions in air. Notably, the specific wear rate decreased as test duration increased under low loads, further suggesting that corrosion-induced volume loss significantly outweighs mechanical wear in this regime. The static corrosion test revealed that volume loss during tribocorrosion was higher than that under static corrosion conditions. While the deposition of corrosion products affected net volume loss, chemical dissolution remained the primary driver of the observed wear trends at low loads. Electrochemical data from anodic polarization curves confirmed that the specimen tested under a 0.98 N load exhibited lower corrosion resistance. Mechanistically, it was suggested that Cl⁻ ions contributed to the overall increase in wear, while NaHCO₃ specifically contributed to the increase in wear in the low-load range. Full article

To investigate the seepage and mechanical behavior of the overlying strata during solution mining in salt deposits, porous sandstones with different grain sizes were selected for study. First, a series of microscopic tests, including SEM, MIP, and NMR, was conducted to characterize the pore structure of the rocks. Subsequently, using a servo-controlled triaxial rock testing system, permeability tests covering the complete stress–strain process were performed under different confining pressures and seepage pressures based on the steady-state method, in order to analyze the seepage and mechanical characteristics of the sandstones during deformation and failure. The results indicate that the investigated aquifer sandstones are characterized by weak cementation, high porosity, large pore size, good pore connectivity, and relatively high permeability. High confining pressure enhances the mechanical strength of the sandstone while reducing its permeability, whereas increasing seepage pressure decreases mechanical strength and enhances permeability during triaxial compression under pore water pressure conditions. Throughout the complete stress–strain process, the evolution of permeability is jointly controlled by the intrinsic pore structure of the rock, the stress loading path, and the failure mode. Under high confining pressure, localized compaction bands may develop, and the formation of such localized structures suppresses any increase in permeability. Acoustic emission shows good correlations with both the stress–strain response and permeability evolution. This study provides new insights into the pore structure of loose, highly permeable sandstones and their hydromechanical coupling behavior throughout the complete stress–strain process. Full article

The Permian Wargal Formation of the western Salt Range preserves a shallow marine carbonate-ramp succession, in which heterogeneity reflects coupled depositional architecture, facies-selective diagenesis, and deformation-related structural compartmentalisation of the Wargal interval. This study integrates balanced restoration with stratigraphic logging, microfacies analysis, paragenetic reconstruction, and quantitative pore-network topology to evaluate how stratigraphic packaging and diagenetic overprint govern connected pathway development within a structurally partitioned fold–thrust setting. Balanced restoration of a representative transect yields 1.1336 km of minimum tectonic shortening (18.7%) and indicates shortening shared between thrust slip and distributed folding, providing an admissible geometric framework for assessing compartmentalisation. The Wargal succession is ~130 m thick and organised into three carbonate packages bounded by laterally persistent argillaceous marker intervals (~21–23 m and ~98–105 m), with grain-supported shoal to shoal-margin facies dominating intervening units. Diagenesis is strongly facies-selective; grain-supported microfacies record progressive calcite cementation that occludes pore throats, whereas mud-supported facies retain microporosity but are preferentially modified by neomorphism, compaction, and pressure-solution fabrics. Image-based analysis of 20 thin-section fields of view shows that pore connectivity varies systematically among microfacies and that a connectivity-weighted index ($I_{\mathrm{conn}}$) covaries more closely with skeleton-derived connectivity than with segmented areal porosity (${\varphi }_{2D}=0.124$–9.750%). The combined results quantify the decoupling between pore volume and connectivity and provide a basis for predicting reservoir-quality evolution from facies architecture, diagenetic sequence, and structural segmentation, with direct relevance to subsurface characterisation of marine carbonate successions in hydrocarbon systems. Full article

Although the dissolution of sparingly soluble salts is of interest to many fields, such as material science, dentistry, and geochemistry, the simplicity of these reactions provides its own motivation for study. Three features of these reactions are examined in this paper: (i) the unusual forms of the kinetic expression that have been used to describe their rates of reaction, (ii) the observation that the rate of dissolution is correlated with the potential difference across the solid-solution interface, and (iii) the observation of non-stoichiometric dissolution. Mechanistic descriptions of the kinetics of dissolution in current use do not account for all these factors, while the surface vacancy model does. In this paper, it is shown that linear kinetics arise from a symmetry of the rates of removal and deposition of anions and cations. On the other hand, non-linear kinetics arise from an asymmetry in the rates of removal and deposition of anions and cations. Because the surface vacancy model is an electrochemical model, the influence of potential difference on the rate of reaction is inherent to the model. A transient, or non-stationary state, version of the model is used to explain how non-stoichiometric dissolution arises. Full article

Rare earth elements (REEs) play a critical role in provenance tracing and the environmental reconstruction of the Earth. However, systematic investigations into the geochemical behavior and fractionation mechanisms of REEs during halite crystallization in brine–salt systems remain limited. This study reports new trace element and REE data for Late Cretaceous halites from the Thakhek Basin, Laos. Ratios of Sr/Ba, Sr/Cu, and V/Cr indicate a marine origin for the halites, which formed under hot climatic and oscillating oxidizing–anoxic redox conditions. Both primary and secondary halites display uniform Post-Archean Australian Shale (PAAS)-normalized REE distribution patterns, characterized by relative enrichment in medium rare earth elements (MREE) and depletion in light (LREE) and heavy rare earth elements (HREE). Similar REE patterns are also observed in halites from other modern and ancient, continental and marine salt basins worldwide. These observations suggest that the influences of parent brine composition and external provenance supplies on REE fractionation are negligible, given the consistent source, salinity, and redox conditions recorded in these halites. Accordingly, REE fractionation in halite was largely controlled by crystallographic effects, with aqueous MREE preferentially incorporated into halite crystals during deposition. In addition, the relatively lower Zr/Hf ratios in secondary halites compared to primary halites further validate the utility of the Zr/Hf ratio for distinguishing authigenic halite from salt modified by diagenesis, weathering, dissolution, or recrystallization. While our results establish a fundamental REE distribution pattern for halite, further research is needed to better constrain the underlying fractionation mechanisms of REEs in evaporite minerals within brine–salt systems. Full article

Pollution flashover accidents of transmission line insulators have a wide impact and low reclosing success rates, posing a serious threat to the safe and stable operation of the power grid. The existing pollution discharge and flashover models of insulator based on equivalent salt deposit density (ESDD) present significant differences from the actual situation. To address this issue, the conductivity of electrolyte solutions experiments is carried out in this paper, and the quantitative functional relationship between conductivity and concentration of typical components is obtained. On this basis, the concept of effective salt deposit density (SDD_e) is introduced to characterize the actual mass of pollution participating in surface conduction per unit area. A DC discharge dynamic model for polluted insulators is established and verified based on SDD_e combined with the discharge development process. Research results indicate that the average difference between the calculated flashover voltage and experimental value is less than 7%. The deviation of flashover voltage between the SDD_e basis model and measured salt deposit density (SDD_m) basis value increases with the increasing proportion of slightly soluble components. With the increase of insulator surface water adhesion, the flashover voltage obtained by the proposed model decreases while the corresponding SDD_m basis value remains constant. The effects of factors such as slightly soluble pollution and surface water adhesion are considered in the proposed model sufficiently. The application of the model based on SDD_e can improve the accuracy of the insulator discharge process and flashover voltage prediction, especially for the complex pollution area. During the generation and propagation of the arc, the leakage current under SDD_m is relatively higher and the pollution layer resistance is lower compared to that under SDD_e; the variations in the pollution layer resistance and leakage current with arc development under SDD_m do not adequately reflect the actual conditions. Full article