As the global energy system accelerates its transition toward renewable energy,electrochemical energy storage devices play an increasingly vital role in ensuring power supply stability and promoting efficient energy utilization.However,low-temperature environments pose a significant challenge to the performance of electrochemical energy storage devices.Especially for widely used lithium-ion batteries,the problems such as significant decrease of charge and discharge capacity,increase of internal resistance and shortening of cycle life are particularly prominent,which seriously limits the commercialization development of lithium-ion batteries in cold regions and other scenarios.To address this challenge,this paper provides a systematic review of current research progress on the performance of electrochemical energy storage devices in low-temperature environments.First of all,focusing on the core research topic of modification and optimization of battery cathode materials and electrolyte systems.This study systematically elucidates the mechanism contributing to battery performance under low-temperature conditions,including changes in material resistivity,reduced reactivity of active materials,and increased viscosity of electrolyte materials.Then,the modification strategies of electrolyte to improve the performance of batteries under low temperature are reviewed and analyzed.In addition,other effective ways to optimize the low-temperature performance of energy storage devices and their mechanisms for improving the electrochemical performance are also expounded.
Polymer composites are the primary materials for water-lubricated bearings owing to their superior wear resistance, low friction coefficient, and resistance to water and corrosion. Their performance directly governs the safety, reliability, and operating costs of the bearing systems. This paper provides a systematic review of the properties of commonly used polymer composites for water-lubricated bearings and recent research progress. It focuses on analyzing the load-carrying capacity, wear resistance, and frictional behavior of different materials, while comparing their relative advantages and limitations. Finally, by addressing the current challenges with existing materials, the review proposes future research directions for high-performance water-lubricated bearing materials and suggests strategies for optimizing their design and engineering applications, aiming to offer valuable insights for further development.
In the process of offshore chemical drive, water drive well network and polydrive well network coexist after well network densification, which exerts a deep influence on oil development. To quantitatively characterize the perturbation degree of injected water and polymer, a water-polymer perturbation coefficient considering the dynamic changes of displacement volume of injected water and polymer is proposed. The production characteristics and laws under different displacement modes are analyzed based on the water-polymer perturbation coefficient, and the control strategies are discussed.The results show that the injected water would compress the polymer displacement area and exert an interference on the polymer front edge. Water-polymer perturbation coefficient has a good correlation with stage net oil increase curve, and water-polymer co-flooding process can be divided into five stages according to the water-polymer perturbation coefficient. In addition, water-polymer co-flooding has a better oil production than pure polymer flooding at the initial stage, but for a long period, development effect of pure polymer flooding is much better, and water-polymer alternating injection can balance the displacement front and improve the development effect. The result has a great significance to quantitatively characterize water-polymer perturbation degree and make adjustment measurements.
To ensure the effect of several rounds of profile control in Bohai oilfield, the adaptability of a drag-increasing in-situ gel profile control agent was investigated specifically in the study. The gelation property, thermal stability and micromorphology after gelation were measured by viscosimetry, rheological analysis and scanning electron microscope respectively. The injectivity, plugging property, selectivity and enhanced oil recovery effect of the profile control agent were investigated by sand packing experiments. The results show that the profile control agent has low initial viscosity, excellent injectability and deep migration performance, and weak chromatographic separation behavior in the reservoir. At the reservoir temperature of 65 ℃, it has a long gelation time, high gelation viscosity and good thermal stability. After gelation, it has a three-dimensional network structure with microspheres as cross-linked nodes inside, and demonstrates shear thickening characteristic at a shear rate of 4~12 s?1. Additionally, the profile control agent possesses excellent selective plugging performance and preferentially enters the breakthrough area to form plugging, , while maintaining a low oil plugging rate in the oil layers. The profile control agent shows a significant effect on enhancing oil recovery and the increase in crude oil recovery rate reaches 15.0%~23.0% after injecting 1.000 pore volume (PV). Generally, the drag-increasing in-situ gel profile control agent can adapt to the reservoir characteristics of Bohai offshore oilfield well, and realize in-depth profile control in the reservoir.
The characteristics and evolution of the imbibition front during spontaneous oil recovery in mixed wetting capillaries are critical for predicting imbibition efficiency in tight oil reservoirs with complex wettability. By establishing a spontaneous imbibition model under mixed wetting conditions, this study investigates the influence of spatially heterogeneous wettability distribution and the degree of mixed wettability on the spontaneous imbibition front distance and the interfacial deformation behavior. The critical condition for achieving efficient spontaneous imbibition in mixed wetting capillarie is identified. A higher water-wetting fraction results in smaller differences in the stabilized static suction front edge distance, achieving optimal oil recovery time more efficiently. Conversely, a larger cosine difference in contact angles between wet and dry sidewalls leads to greater disparities in this critical parameter. By combining simulation data with a fitting formula for static suction front edge distance variations, combined with analytical solutions for the front distance, we can quantitatively characterize the dynamic patterns of front distance changes and interfacial deformation characteristics in mixed-wetting capillary systems. These findings provide theoretical support for efficient and low-carbon development strategies in mixed-wet tight oil reservoirs.
With the development of large-scale storage tanks,structural safety issues such as foundation settlement and structural deformation that affect the operation of large storage tanks have increasingly become the focus of equipment management and inspection personnel.Research on foundation settlement detection and structural integrity evaluation of large storage tanks is of practical significance for ensuring the safe operation.This article analyzes the types and typical damage forms of tank foundation settlement,and proposes requirements for tank foundation settlement detection based on the characteristics of different tank service stages such as design,construction,and regular inspection.It clarifies the detection and evaluation methods for different types of settlement,and focuses on the research of graded evaluation methods for uneven settlement around the tank.A 4-level evaluation method for basic uneven settlement,including settlement difference evaluation,deviation from the plane settlement amplitude evaluation,local non-uniform plane settlement evaluation,and stress analysis evaluation,is proposed to effectively support equipment management and inspection personnel in conducting structural suitability evaluation under tank foundation settlement conditions.
During the shutdown period of the J-Y refined oil product pipeline, there is a significant difference between the temperature of the transported oil and the outside soil temperature, which leads to a pressure drop in the pipeline after the shutdown. When the pressure at the high point of the pipeline drops below the saturated vapor pressure, air resistance occurs inside the pipeline, making it impossible to maintain pressure. This further poses a potential threat to the safe operation of the pipeline system. The SPS software was used to establish a pipeline model to simulate the equivalent soil temperature distribution along the pipeline. Through simulation and analysis, the inlet temperature error at the terminal station was effectively corrected, thereby obtaining the average soil temperature along the pipeline and the temperature drop range after shutdown. A fitting equation was utilized to reveal the relationship of equivalent soil temperature change over time. Combined with the pre-pump temperature measurement value and the equivalent soil temperature value obtained from the simulation, a shutdown operation was carried out after the system had been running for a period of time, and the trend of temperature and pressure changes after shutdown was simulated by the SPS model. The analysis shows that the temperature difference between oil and soil shows an exponential relationship with the pressure preservation time after shutdown. If the temperature difference between oil and soil before shutdown is small enough, vaporization is less likely to occur in the whole line after shutdown. If the temperature difference between oil and soil before shutdown is negative, the pressure in the pipe will increase after shutdown.
Compared with clastic reservoirs,carbonate reservoirs have extremely strong heterogeneity,multiple types of storage spaces,and uneven development of pores,caves,and fractures.How to characterize the three-dimensional storage space of strongly heterogeneous carbonate gas reservoirs is the key to fine reservoir description.By integrating geological,logging,seismic,and production dynamic data with reservoir characterization insights,this study focuses on the Maokou Formation fracture-dong carbonate reservoir in Hechuan Block.Random modeling combined with deterministic modeling methods is used to gradually construct a detailed geological model of the reservoir with various attributes such as structure,sedimentary facies,reservoir classification,porosity,permeability,and gas saturation,quantitatively characterizing the distribution characteristics of reservoir attributes.By combining geostatistics with multi-attribute collaborative simulation technology,this paper establishes a multi-scale integrated fracture-hole model,quantitatively characterizes the spatial distribution characteristics of reservoirs,and forms a set of fine fracture-hole carbonate reservoir modeling methods based on sedimentary facies-reservoir type classification control and multi-scale information fusion.
In order to resolve the limitation of the built-in catalyst database in Aspen simulations,a dual-rate kinetic model based on the Power Law (PL) formulation is proposed.The kinetic model is integrated into Aspen Plus for multi-process simulation of hydrogen production.By incorporating the influence of catalysts on the reactions during the simulation,a more realistic chemical process simulation is achieved.The dual-rate kinetic model accurately reflects actual hydrogen production conditions: increasing temperature and reducing liquid hourly space velocity (LHSV) both enhance methanol conversion and simultaneously increase CO selectivity.The steam-to-carbon molar ratio has a minor impact on the reaction.By considering energy consumption,the optimal range of the steam-to-carbon molar ratio is 1.0~1.4.Under the condition in which the reaction temperature is 280 °C and the feed flow rate is 1.5 mL/min,the multi-process simulation results demonstrate that the CO concentration in the product is reduced to only 6.89 μL/L after methanol steam reforming, water-vapor shift,and CO selective oxidation.This CO concentration meets the requirements for proton exchange membrane fuel cells(PEMFC).
