Against the background of fossil fuel exhaustion and lithium resources shortage,sodium?ion batteries are considered promising secondary batteries due to their abundant resources,low theoretical cost, good quick?charge performance and excellent low?temperature performance.They are expected to play a key role in developing new energy,large?scale energy storage and low?speed electric vehicles.The selected cathode material is one of the important factors influencing the energy density,cycling performance and rate performance of a sodium?ion battery.This paper reviews the cathode materials of sodium?ion batteries,including transition metal oxides, polyanionic compounds,Prussian blue compounds and organic compounds.The paper introduced the advantages and disadvantages of sodium?ion batteries,analyzed the characteristics and research focuses of various cathode materials,and provided an outlook on the development direction of cathode materials for sodium?ion batteries.
Taking oily sludge as the research object,this paper conducted solidification experiments with fly ash, clay, and laboratory?made liquid binder as a composite binder.It explored the effects of dosages (mass fractions) of binder components on the solidified block strength and determined the optimum dosage of the curing agent. The results show that the strength of the solidified block is the best in the case of the fly ash dosage of 30%,the clay dosage of 10% and the liquid binder dosage of 5%. Under the optimal process conditions, the cold strength of the solidified block is 2.19 MPa and the hot strength is 2.21 MPa, which indicates that it has sufficient cold strength and thermal stability. The forming mechanism of the solidified block was studied with the help of Fourier transform infrared spectroscopy (FT?IR),X?ray diffraction (XRD), and scanning electron microscopy (SEM). The forming mechanism of the solidified block was put forward according to the characterization results.
During gravel packing operations in offshore oilfields, incomplete packing or packing failure may occur due to design, irregular borehole, formation, and other reasons, which has a great impact on the production of oil wells. A new type of multi?channel bypass screen is designed and developed. After conventional packing is completed, the gap section continues to be packed through the bypass channel. The performance of the designed multi?channel bypass screen is evaluated with a self?developed large full?scale horizontal well gravel packing test simulation system, and the following conclusions were obtained through experiments. In the gravel packing experiment through the bypass pipe without a sand bridge, the packing efficiency of the bypass section measured is 100.0%. When the glass conveying pipe is connected, the ratio of the return flow rate at the outlet to that of the glass conveying pipe is 0.68
The sand?carrying migration law of slick water in fractures is of great guiding significance to the practice of slick water fracturing.Sand transport profiles with different injection parameter combinations were tested by a visual parallel plate fracture simulator.The results show that the sand?carrying capacity of the slick water is favorable under the combination of slick water for fracturing +70~140 mesh proppant +8% sand ratio.In this case,no sand banks are observed at the fracture inlets,and the proppant does not fill the fractures adequately,under the combinations of low?viscosity slick water +40~70 mesh proppant +10% sand ratio and high?viscosity slick water +20~40 mesh proppant +20% sand ratio, the amount of sand filling fractures is large, and the sand banks in deep fractures are high,while the filling at fracture inlets is poor.With the increase in construction displacement, the various combination modes all exhibit growing positions of the front edges of the sand banks, decreasing heights of front edges, and insignificant changes in balance heights. Injection combination is an important aspect affecting the sand bank pattern. The sand bank patterns and characterization parameters corresponding to different injection parameter combination modes vary greatly. Therefore, the combination mode needs to be optimized on site to improve the conductivity of fractures at the inlet.
CeO2?modified three?dimensional nitrogen? and phosphorus?doped carbon?based catalysts (CeO2?NPC) were prepared with cerium chloride hexahydrate as the precursor,sodium chloride as the template,and milk as the carbon source.The results of rotating disc electrode (RDE) and rotating ring?disc electrode (RRDE) tests were used to analyze the influence of catalyst preparation conditions on the oxygen reduction reaction (ORR) process.The influence of the synthesis process on the structure was investigated by X?ray photoelectron spectroscopy (XPS) and Raman spectroscopy.Heteroelements such as N and P spilled out with small molecules during calcination temperature increase.In this process,the degree of defects on the carbon carriers was increasing and the content of CeO2 was invariably in an increasing trend.
Supported SnCl2 is a mercury?ree catalyst for acetylene hydrochlorination.5.0%Sn(acac)2Cl2/AC catalyst was prepared by introducing acetylacetone ligand to enhance the catalytic performance of SnCl2 in acetylene hydrochlorination.The results show that the acetylene conversion of 5.0%Sn(acac)2Cl2/AC catalyst is up to 96% under the conditions of acetylene?to?hydrogen chloride molar ratio of 1∶1.1,170 ℃ and GHSV(C2H2) of 90 h-1, which is higher than that of the 5.0%SnCl2/AC catalyst. The physical and chemical properties of the catalysts before and after the reaction also proved that the introduction of acetylacetone ligand can enhance the acetylene adsorption capacity of the SnCl2 catalyst and inhibit Sn loss during the reaction.Therefore,the activity and stability of the SnCl2 catalyst were effectively improved.
Conductive polymers have attracted the interest of scientific researchers due to their high electrical conductivity,light weight,corrosion resistance,and good electrical and optical properties.As a typical conductive polymer,polypyrrole has attracted much attention because of its simple synthesis conditions,good environmental stability,environmental friendliness,and the wide range and tunability of electrical conductivity.However,it suffers from some shortcomings such as difficulties in dissolution and melt and poor mechanical properties and processing properties,which limit its application.Composites formed by polypyrrole and other materials not only improve the original shortcomings of polypyrrole but also combine the advantages of the two to endow the materials with new properties and broaden their application fields.This paper briefly described the main synthesis methods of polypyrrole,analyzed the advantages and disadvantages of each method,and summarized its applications in the fields of supercapacitors,gas sensors,and biological tissue engineering.The paper also discussed the problems facing polypyrrole composites and corresponding solutions and provided an outlook on their future development.
A micropore throat plugging material was prepared by emulsion polymerization. Its structural characteristics were analyzed by Fourier transform infrared (FT?IR) spectrum analysis, Raman spectrum analysis, and thermogravimetric?differential thermal analysis (TG?DTA). The particle size range of the synthesized product was determined by a laser particle size analyzer. The inhibition performance and plugging performance of the micropore throat plugging material were also investigated. The results show that the thermal decomposition temperature of the synthesized product is 321.0 °C and that its particle size distribution is between 500 nm and 2 250 nm. When the quantity of the micropore throat protection material used is 1.5%, it performs excellently in inhibiting clay hydration. Moreover, the inhibition effect significantly improves when the micropore throat plugging material is compounded with 0.5% sodium chloride. The filter membrane plugging experiment proves that the filter membrane with a pore diameter of 0.45~10.00 μm can be effectively plugged by the proposed material, and the plugging time is up to 35.43 min when the plugging quantity is 1.5%. After aging at 120 °C for 16 h, the high temperature and high pressure filtration loss is 10.0 mL when the amount of the micropore throat plugging material added is 1.5%.
A self?made long?chain cationic surfactant (SFC111) and a low interfacial energy substance (SFC115) were used to prepare a cationic emulsion for further application as surfactant for low permeability oil and gas reservoirs. The dispersion of the emulsion in water, the contact angle of the core before and after the emulsion treatment and the surface tension were investigated by particle size analyzer, contact angle meter, and rotating drop interfacial tension meter, respectively. The thermodynamic parameters of the emulsion at 20 ℃ and 70 ℃ were calculated. Particle size of 0.5% concentration emulsion is D50=420.8 nm at 20 ℃, D50=728.0 nm at 70 ℃.The contact angle of clear water on the surface of the core increases from 10° to 120°. The emulsion could reduce the surface tension of water to 24 mN/m at 70 ℃, indicating the good waterproof lock performance. The adsorption characteristic of emulsion conforms to the langmuir adsorption theory. The thermodynamic results show that as the temperature increases, the amount of adsorption on the surface of the emulsion decreases, the area occupied by the molecules on the surface of the emulsion goes down, and the thickness of the adsorption layer decreases.
Given the deep burial depth,high temperature and high pressure, significant heterogeneity of the deep gas reservoirs in the southern margin of the Junggar Basin,the temporary plugging and diverting stimulation technology with stratification and segmentation was used to achieve efficient stimulation and improve the producing degree of those reservoirs.The plugging of fractures and perforations by temporary plugging agents under the high temperature of 140~180 ℃ was experimentally investigated,and the degradation rates and pressure?bearing capacities of five temporary plugging materials were evaluated respectively.The results show that the commonly used temporary plugging materials will soften under a high temperature and tend to flow with the carrying fluid under the displacement pressure difference, resulting in a decreased pressure?bearing capacity of the temporary plugging section and the loss of plugging effect. A temporary plugging material with a pressure?bearing capacity of 30.00 MPa at 180 ℃ was selected, and its field application results showed that the temporary plugging improved production significantly.
Accurately predicting the power consumption of crude oil pipelines is conducive to controlling the energy consumption level of such pipelines and fully tapping the energy saving potential of crude oil pipeline transportation systems. Actual operation data of such pipelines have the characteristics of large fluctuation range serious noise interference, and information redundancy, which affect the accurate prediction of pipeline power consumption. To solve these problems, this paper proposes a power consumption prediction model based on a hybrid neural network. The daily operation data of crude oil pipelines are decomposed by complete ensemble empirical mode decomposition with adaptive noise. Principal component analysis is performed to reduce the dimensions of the decomposed data. The improved particle swarm optimization algorithm is applied to adjust the structural parameters of the neural network. The proposed model is applied to predict the power consumption of a crude oil pipeline and compared with some common prediction models. The results show that the decomposition algorithm can improve the prediction accuracy of the model. The hybrid neural network model has the highest prediction accuracy. The average absolute error of the test set is 5.394%, which is 39.200% lower than that before the decomposition algorithm is used.
To evaluate the consequences of leakage accidents of the shallow subsea natural gas pipeline, this paper builds a calculation model of the shallow subsea pipeline leakage and diffusion process in light of computational fluid dynamics and multiphase flow theories for the strait?crossing section of a natural gas pipeline abroad. Three main factors, leakage aperture, leakage rate, and water flow velocity, are selected as condition variables to simulate the motion process of the gas?liquid two?phase flow under different conditions. The results show that underwater gas diffusion can be divided into three stages: the formation of gas masses above the leakage hole, the mushroom?like rise of gas masses, and the splitting of gas masses from large bubbles into small ones. Leakage aperture and leakage rate have a significant effect on the time when the underwater gas diffuses to the water surface. A larger leakage aperture and a higher leakage rate lead to a larger gas leakage amount, which further results in larger volumes of underwater air masses and ultimately a shorter time for them to reach the water surface. Water flow velocity has a significant effect on gas diffusion trajectory. As water flow velocity increases, the angle between the gas trajectory and the seabed decreases, and the diffusion distance along the ocean current direction becomes longer. This study can provide scientific guidance for emergency treatment of underwater natural gas pipeline leakage accidents.
