Search Results (650)

Decarbonization requires oil and gas companies to combine gas-monetization projects with measures to improve operational efficiency and reduce emissions. This study develops a scenario-based approach to portfolio selection for a gas-condensate asset, accounting for economic value, risk, net gas-resource requirements, and carbon effects. Projects are evaluated relative to baseline pipeline gas sales. Within-scenario uncertainty is represented using triangular distributions and Latin hypercube sampling. Feasible portfolios are generated by exhaustive enumeration, followed by Pareto selection and risk-adjusted ranking. The synthetic model-based application considers six project solutions, generating 63 nonempty combinations. Under the specified assumptions, the number of feasible portfolios decreases from 37 in the inertial scenario to 19 in the moderate scenario and 2 in the stringent scenario. The mere presence of a decarbonization component does not determine project priority. Operational projects gain portfolio significance when they improve resource use and carbon performance. The capital-intensive project combining value-added gas processing with CCUS plays a different role: for the project set considered, it becomes necessary only when the minimum portfolio carbon requirement exceeds 1.90 but does not exceed 2.40 million t CO₂e/year. Above this level, no feasible portfolio can be formed. This threshold interval is case-specific. These results reveal how decarbonization can affect both project ranking and portfolio feasibility, highlighting an asset-level energy–environment–economy trade-off. Full article

CO₂ flooding is essential for enhancing oil recovery in low-permeability reservoirs; however, the large viscosity contrast between CO₂ and crude oil leads to severe gas channeling and low sweep efficiency. In this study, a binary composite system was constructed with a gas-soluble nonionic surfactant (OXO1312) as the foaming core and nano-SiO₂ as the Pickering stabilizer. The solubility of the surfactants in scCO₂ was evaluated at 60 °C and 20 MPa using a variable-volume apparatus, the foam performance was assessed by the Waring Blender method, and the foam morphology was observed by optical microscopy. The nonionic surfactants exhibited markedly higher scCO₂ solubilities (>2 wt%) than the anionic surfactants (<1 wt%), following a clear carbon-chain-length window effect. OXO1312, combining high CO₂-philicity with an appropriate EO number, was selected as the optimal foaming agent. The addition of 1.5 wt% nano-SiO₂ increased the drainage half-life of the OXO1312 system by 84% through pronounced Pickering stabilization. The binary system remained stable below 50 °C under moderate salinity, whereas the half-life declined sharply above 70 °C. These findings provide a theoretical basis for the formulation design of CO₂ foam flooding systems for CCUS-EOR. Full article

Tight sandstone gas reservoirs are characterized by low single-well productivity, rapid natural decline, and generally low recovery rates, which limit the effectiveness of conventional development strategies. The injection of CO₂ into tight gas reservoirs offers broad prospects for both enhanced gas recovery (EGR) and integrated CO₂ capture, utilization, and storage (CCUS). However, during the depletion and CO₂ injection processes, fracture conductivity, reservoir fluid distribution, and gas–water relative permeability evolve continuously, exhibiting pronounced time-varying behavior. Conventional models have certain limitations in characterizing these time-varying mechanisms, often resulting in significant discrepancies between predicted performance and actual conditions. To address this, we develop a robust and generic model that explicitly incorporates the time-varying mechanisms and stress sensitivity. This model also accounts for the non-equilibrium flash (NEF) behavior of the gas–liquid mixture during CO₂ injection into tight gas reservoirs. The successive substitution iteration method is adopted for non-equilibrium flash calculation, and the Newton–Raphson iteration (NRI) method is used for obtaining a fully implicit solution of the reservoir flow equations. The accuracy and reliability of the proposed model are verified through comparisons with commercial simulator results, and a quantitative comparison with traditional models highlights the key discrepancies caused by neglecting time-varying mechanisms. Parametric analyses further clarify the impacts of time-varying behavior and stress sensitivity on CO₂-EGR performance and CO₂ sequestration efficiency. The results show that the displacement process of CO₂ in tight gas reservoirs can be divided into four characteristic stages. The results also indicate that if the time-varying effects and the stress sensitivity of the reservoir permeability are ignored, the calculations tend to overestimate the true gas production capacity of the reservoir and underestimate the CO₂ sequestration performance. Full article

This paper explores the barriers impacting the electrolyzer industry in emerging hydrogen-transition economies like India, assesses how these barriers interact, and proposes a phased strategic intervention roadmap that supports sustainable industry growth aligned with the national decarbonization goals. Through a detailed literature review, expert opinions, and multi-stage validation, nine barriers were analyzed using DEMATEL methodology to classify cause-effect relationships and identify their significant interdependencies. These challenges were then grouped as root causes, pivot barriers, and symptom barriers to prioritize the interventions. Policy uncertainty and regulatory gaps emerged as the most influential barrier, followed by low technology awareness and a shortage of skilled workers. Considering the existing energy resources the country has, the proposed coordinated strategy suggests short- and long-term actions, including green hydrogen-specific regulations; technology and workforce development; water-efficient electrolyzer technologies; expanded storage and distribution; low-carbon alternatives with CCUS; and tailored financial support to accelerate a resilient, environmentally responsible green hydrogen ecosystem in India. The study’s novel causal-mapping approach, combined with a phased intervention roadmap, helps stakeholders align risk-mitigation and investment decisions to support balanced, sustainable growth by integrating clean or low-carbon hydrogen technologies in developing economies like India. Full article

Coal-dependent regions face a multidimensional transition challenge that extends beyond energy substitution and requires coordinated transformation of industrial systems, landscapes, infrastructure, governance and local economies. Using a structured narrative review and framework-building approach, this paper develops a systems-based framework for sustainable post-lignite transition, using Western Macedonia as the main integrated case and Megalopolis as a comparative Greek lignite region. The proposed approach integrates four interrelated domains: subsurface and geological potential, industrial decarbonisation pathways, post-mining land and infrastructure reuse, and socio-economic and governance transition. Particular emphasis is placed on the role of carbon capture, utilisation and storage (CCUS), low-carbon industrial technologies, renewable energy integration, energy-storage options, land rehabilitation, heritage valorisation and place-based development strategies. The analysis highlights that successful post-coal transition depends not only on the availability of individual technological solutions, but also on their spatial, environmental, economic and governance compatibility within the regional system. By aligning geological knowledge, engineering innovation, environmental management and just-transition planning, the paper proposes an integrated planning framework intended to structure the consideration of multiple forms of evidence in former lignite regions. The framework is broadly consistent with the Sustainable Development Goals, particularly those related to clean energy, resilient infrastructure, sustainable communities, responsible land reuse, climate action and ecosystem restoration, and offers transferable insights for European coal regions seeking resilient, diversified and low-carbon development pathways. Full article

Plastic film mulching (FM) improves crop productivity in dryland agriculture but risks soil quality degradation under continuous chemical fertilization. Under FM with optimized nitrogen (N) input from a controlled-release and conventional urea blend (CCU), straw return (SR) management may either contribute to grain yield or alter aggregate-associated N pools. A two-year film-mulched experiment was conducted with three treatments: no fertilization (CK), CCU alone (CU), and CCU plus SR (CS). Compared with CU, CS did not further increase grain yield despite greater total N uptake during critical growth stages. However, CS increased the proportion of large macroaggregate (LM) by an average of 10.0 percentage points and the mean weight diameter by 35.7%, and also increased N concentration in most aggregate fractions. A significant increase in N stock was detected in the LM fraction in both years. In contrast, N stock in the microaggregate (MI) was significantly lower under CS in 2020, whereas N stocks in small macroaggregate (SM), silt and clay (SC), and bulk soil were not significantly affected in either year. SM N stock was positively correlated with grain yield in the pooled dataset, but this association was attenuated after controlling for year and should therefore be considered exploratory. Overall, CS maintained grain yield comparable to CU while altering aggregate-associated N distribution, suggesting a potential decoupling between short-term yield and aggregate-associated N pools; however, the origin of the additional aggregate-associated N could not be resolved without isotopic tracing. Full article

Occupational burnout among Critical Care Unit (CCU) staff is a pressing issue, yet the relationship between parental burnout and this high-demand professional domain remains underexplored. Thus, this study aimed to analyze the association between parental and occupational burnout in critical care healthcare professionals. A multicentre cross-sectional study was conducted across three CCUs in hospitals within the Vigo Health Area (northern Spain). The sample included 106 CCU staff members with dependent children. Data were collected using the Burnout Screening Inventory, Parental Burnout Assessment, and Oslo Social Support Scale. Although the overall prevalence of occupational burnout was low in this sample, total parental burnout emerged as a statistically significant positive predictor of occupational burnout (β = 0.303, p = 0.003). Among its dimensions, parental emotional distancing acted as the most salient predictor (β = 0.409, p = 0.006). Parental burnout is significantly associated with higher levels of occupational burnout among CCU professionals, with parental emotional distancing being the most relevant dimension in this relationship, with perceived social support as an inverted association. These findings highlight the co-occurrence of both phenomena and the need to acknowledge the intersection of family demands and high-intensity work environments when addressing occupational wellbeing in critical care settings. Full article

Functional polymer catalysts have emerged as a transformative class of materials for CO₂ capture and conversion, offering exceptional tunability, high CO₂ affinity, and excellent recyclability. This review provides a comprehensive polymer-centric analysis of four major classes of functional polymer catalysts—linear and soluble polymers, crosslinked networks and resins, porous organic polymers (POPs), and polymer–metal hybrids—with a unified focus on their roles in CO₂ capture, CO₂ cycloaddition to epoxides, CO₂ hydrogenation, and integrated carbon capture and utilization (CCU) strategies. We discuss how the polymer backbone chemistry, active site density, microenvironmental effects, hydrophilic–hydrophobic balance, and pore confinement collectively govern the CO₂ uptake capacity, activation, conversion, and selectivity of these materials. The stability, recyclability, and green metrics of the polymer catalysts were critically assessed, and their performance was benchmarked against that of inorganic supports, metal–organic frameworks (MOFs), and covalent-organic frameworks (COFs). Current challenges, including structure–activity gaps, operando characterization, standardized performance reporting, processability, and scale-up, are also discussed. Full article

Precision medicine in the intensive care unit (ICU) is increasingly defined by individualized, bedside physiologic assessment rather than protocolized treatment algorithms. Critical care ultrasound for targeted volume management (CCUS-TVM) operationalizes this shift by helping clinicians answer two questions before administering intravenous (IV) fluids: is it safe, and will it be effective? Static measures, such as inferior vena cava (IVC) assessment and the Venous Excess Ultrasound Score (VExUS), identify venous congestion and predict fluid intolerance, while dynamic measures, such as change in left ventricular outflow tract velocity time integral or carotid flow time after passive leg raise, predict volume responsiveness. Together, these tools allow clinicians to tailor resuscitation to an individual patient’s underlying hemodynamics, complementing the four-interface model of shock physiology. Recent meta-analyses and the 2024 Society and Critical Care Medicine and 2026 Surviving Sepsis Campaign guidelines show that CCUS-TVM—particularly dynamic assessment—contributes to fewer episodes of renal replacement therapy and mechanical ventilation, shorter ICU stays, and decreased mortality. Beyond clinical benefit, this communication presents an original, exploratory estimate of the potential per-patient cost savings associated with dynamic CCUS-TVM in sepsis— approximately $2600–4400—driven by reductions in renal replacement therapy, mechanical ventilation, and ICU length of stay. Taken together, CCUS-TVM offers a clinically validated and economically favorable framework for advancing precision medicine in resuscitation. Full article

The continuous increase in carbon dioxide (CO₂) has intensified the need for sustainable technologies to mitigate greenhouse gas emissions. Carbon Capture and Utilization (CCU) represents a promising strategy to convert captured CO₂ into valuable products, contributing to climate change mitigation and the circular economy. This review provides an overview of the main carbon management pathways, including Carbon Capture and Storage (CCS), Carbon Capture, Utilization and Storage (CCUS), and CCU, with a focus on biological CCU (bio-CCU) based on microalgae and carbonic anhydrases (CAs). Particular attention is given to the role of CAs as highly efficient biocatalysts that accelerate CO₂ hydration, enhancing inorganic carbon availability. Recent advances in enzyme immobilization technologies and support materials are examined, highlighting their potential to improve enzyme stability, reusability, and process performance. Furthermore, the integration of immobilized CAs with microalgal cultivation systems is explored as an emerging strategy in which CAs facilitate inorganic carbon availability and delivery, potentially enhancing its photosynthetic fixation by microalgae and biomass productivity. Building on previous studies on microalgal bio-CCU and CA-assisted carbon capture, this review provides an integrated perspective on CA immobilization strategies, support materials, and their potential implementation in microalgal bio-CCU systems, highlighting how enzyme immobilization can connect enzymatic CO₂ conversion with microalgal carbon fixation and contribute to sustainable CO₂ valorization and environmental remediation. Full article

Carbon capture, utilization and storage (CCUS) is a critical technology for the fossil energy industry to achieve the dual carbon goals. Organic amine-based absorption methods, represented by mono-ethanolamine (MEA), methyl-diethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP), are currently the most widely adopted approaches for carbon dioxide capture. If the concentration of leaked organic amines exceeds the safety threshold, inhalation will cause severe respiratory irritation and even serious illnesses in humans. Accordingly, in situ monitoring of organic amine concentrations in waste gas is of great significance for process optimization, environmental protection, early health warning, energy conservation and emission reduction. In this study, a metal oxide semiconductor (MOS) sensor array was developed to identify categories and concentration variations in small-molecule organic amines. To realize effective gas classification and accurate concentration prediction, single-component gas data and mixed gas data with varying concentrations of the three amines collected in the laboratory were adopted to train a one-dimensional convolutional neural network (1D-CNN) and a bidirectional gated recurrent unit (Bi-GRU) via five-fold cross-validation. The proposed model achieved a classification accuracy of 0.9969 ± 0.0006. For MEA concentration prediction, the optimal determination coefficient (R²), root mean square error (RMSE), and mean absolute error (MAE) were 0.9969, 2.1306 and 1.5503, respectively. The experimental results demonstrate that the proposed method possesses promising practical application prospects in in situ gas monitoring and early hazard warning. Full article

During deepwater carbon capture, utilization, and storage (CCUS) riserless (open-loop) drilling, the drill string is directly exposed to a complex marine environment, resulting in mechanical behavior and failure mechanisms that differ from those under conventional riser-supported drilling conditions. This study develops a full-depth dynamic model of a drill string in riserless drilling that covers both the seawater and formation sections. In the seawater section, the Morison equation and a wake oscillator model are introduced to represent wave–current loading and vortex-induced vibration (VIV), respectively. In the formation section, the equations of motion are derived from Hamilton’s principle, and nonlinear contact between the drill string and borehole wall is treated using the penalty function method. A deepwater CCUS drilling operation in the South China Sea is examined to systematically evaluate drill-string deformation, internal-force and stress distributions, heave transmission, and full-depth fatigue damage. The results reveal a dual-scale coupled response: large-displacement, low-frequency drift occurs in the in-line direction, whereas small-displacement, high-frequency oscillation occurs in the cross-flow direction. The region near the mudline is the principal mechanical weak point and fatigue-control location along the entire well depth. Since the drill string moves downward, every joint passes through this hotspot, making cumulative fatigue damage a primary concern for drill-string integrity management. Damage localization is primarily caused by the combined effects of axial-bending stress and high-frequency VIV. The effectiveness of the passive heave-compensation sub is strongly load dependent. It effectively suppresses the transmission of large-scale axial displacement but provides limited attenuation of high-frequency weight-on-bit (WOB) fluctuations. These findings provide a theoretical basis for drill-string design, integrity assessment, and operating-parameter optimization in deepwater CCUS drilling. Full article

The Chang 8 reservoir in the Baima Middle Block of the Ordos Basin is an ultra-low-permeability reservoir that has faced formation-pressure depletion, a rising water cut, and poor remaining-oil recovery during long-term water-injection development. CO₂ flooding in CCUS can simultaneously enhance oil recovery and achieve carbon sequestration; however, comprehensive and integrated research on the CO₂–crude oil phase behavior, miscibility characteristics, and nonlinear flow in porous media for this block is still lacking. To address this gap, this study used crude oil and natural cores from the block and natural cores to conduct a series of experiments at 70 °C, including PVT high-pressure physical-property tests, CO₂ constant-mass-expansion tests, slim-tube minimum-miscibility-pressure (MMP) tests, pendant-drop oil–gas interfacial-tension measurements, and CO₂-flooding threshold-pressure-gradient measurements in cores of different permeability. The results showed that as the CO₂ mole fraction increased from 0% to 61.78%, the bubble-point pressure of the crude oil rose from 17.424 to 22.575 MPa, the viscosity decreased from 9.026 to 4.906 mPa·s, and the volumetric expansion coefficient increased from 1.0000 to 1.1454. As the water cut increased from 0% to 80%, the apparent MMP of CO₂ increased from 15.83 to 17.69 MPa. The oil–gas interfacial tension gradually decreased with increasing system pressure, and droplet instability and atomization occurred under near-miscible high-pressure conditions. The CO₂-flooding threshold pressure gradient decreased with core permeability following a power-law relationship, and a knee-like trend appeared near 0.5 mD within the limited permeability dataset of this study; this trend cannot be generalized without further experimental evidence. This study comprehensively reveals the coupled mechanisms of phase behavior, miscibility, and nonlinear flow during CO₂ flooding in the target block, providing experimental and theoretical support for optimizing the injection pressure and reservoir-stimulation schemes of CCUS-EOR in ultra-low-permeability reservoirs. Full article

In CO₂ flooding, variations in mobility and formation heterogeneity may cause gas to traverse high-permeability or interconnected channels, leading to ineffective gas circulation. This limits recovery rates, ultimately leading to reduced financial benefits. Consequently, the identification of CO₂ gas channeling becomes crucial for developing targeted management strategies and improving the efficacy of CCUS-EOR operations. This paper applies an established AHP–fuzzy comprehensive evaluation framework to the screening and prioritization of gas-channeling risk in an ultra-low-permeability CO₂-EOR reservoir. This approach combines six static geological parameters and three dynamic production parameters as indicators, enabling a comprehensive analysis of potential gas channeling in the A block of the Haian Oilfield. This method was applied to the production data from the A block, showing strong consistency with the observed production response. The results offer significant technical assistance and theoretical understanding for the scientific identification, risk evaluation, and subsequent management of CO₂ gas channeling in oilfields. Full article

Sodium molybdate (Na₂MoO₄) is attractive for lithium storage because of its multielectron conversion chemistry, but its low electrical conductivity and structural reconstruction during cycling limit active-material utilization and long-term reversibility. Here, hierarchical C/Cu₂O/Na₂MoO₄ composite fibers were constructed by combining a cotton-derived micro/nanofibrous carbon framework with Cu₂O interfacial modification and electrostatic layer-by-layer (LbL) assembly. The resulting architecture retains the interconnected fibrous structure of the original cotton fibers. A Na₂MoO₄-containing active layer is constructed on the Cu₂O-modified carbon fiber surface, and its loading can be regulated by changing the number of LbL assembly cycles. When evaluated as an anode for lithium-ion batteries, the C/Cu₂O/Na₂MoO₄-50 composite exhibits the best overall electrochemical performance, with an initial Coulombic efficiency of 65.2% and a reversible capacity of approximately 579.3 mAh g⁻¹ after 1000 cycles, whereas pristine Na₂MoO₄ retains only about 66.7 mAh g⁻¹. The hierarchical fibrous carbon network supplies long-range electron conduction, while the micro- and nanoscale fiber surface places the conversion-active phase close to the electrolyte and shortens the Li⁺ transport distance. The Cu₂O-modified surface provides the interface for subsequent LbL deposition, allowing Na₂MoO₄ to remain distributed along the conductive fiber rather than forming an isolated bulk active phase. This work shows that combining biomass-derived structural inheritance with controllable LbL assembly provides a viable route for regulating the integration and utilization of conversion-active phases in lithium storage electrodes. Full article