Research Progress on Stabilization and Enhancement of Photocatalytic Activity of WO_3-x
Zhao Dongxue，Zhang Jing，Wang Fangfang
2021, 34 (1): 1-6. DOI:10.3969/j.issn.1006‐396X.2021.01.001
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It is an effective way to enhance the photocatalytic activity by fabricating some defects such as oxygen vacancy into WO₃ lattice to make nonstoichiometric WO_3-x. This paper firstly describes the mechanism of the effect of oxygen vacancy on the photocatalytic activity of WO₃, and then, reviews the influence of the localized surface plasmon resonance (LSPR) effect and the synergistic effects of noble metal/carbon containing materials, and oxygen vacancy. Finally, prospectsing and challenging of WO3-x application in the field of photocatalysis are discussed in the end of this work.
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Preparation of V₂O₅/g⁃C₃N₄ Catalyst and Desulfurization Ability in Model Oil
Zhang Hao， Li Xiuping， Zhao Rongxiang
2021, 34 (1): 7-14. DOI:10.3969/j.issn.1006-396X.2021.01.002
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The V₂O₅/g⁃C₃N₄ catalyst was prepared by calcination method, using melamine, ammonium metavanadate, boric acid as precursors and methanol as solvent. The structure and morphology of the catalyst were characterized by X⁃Ray Diffraction (XRD), Fourier transform infrared spectroscopy (FT⁃IR), X⁃ray photoelectron spectroscopy (XPS), scanning tunneling microscope(SEM) and brunauer⁃emmett⁃teller(BET). The desulfurization ability of dibenzothiophene (DBT) in model oil was investigated using V₂O₅/g⁃C₃N₄ as catalyst, acetonitrile as extractant and H₂O₂ as oxidant. The effects of reaction temperature, amount of catalyst and extractant, n(H₂O₂)/n(S) molar ratio, and different sulfides on desulfurization rate were investigated. Under the optimum conditions: 5.0 mL model oil, 3.0 mL acetonitrile, n(H₂O₂)/n(DBT)=8, 0.02 g of catalyst, temperature was 30 ℃ and reaction time was 60 min, the desulfurization rate of DBT can reach 91.9%, which can also keep at a higher value at 85.7% after 5 times of catalyst regeneration.
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Progress of Residual Marine Fuel Desulfurization Technology
Ma Rui1， Song Yongyi， Zhang Qingjun， Zhang Shudong， Liu Jihua， Li Xiaohui， Zhang Qingyao
2021, 34 (1): 15-21. DOI:10.3969/j.issn.1006-396X.2021.01.003
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With the implementation of the International Maritime Organization (IMO) sulphur limit policy for marine fuel in 2020, residual marine fuel desulfurization technology has brought widespread attention. The heavy oil is the main component of residual marine fuel, and desulfurization technologies of heavy oil could be categorized as two types: hydrogenation and non⁃hydrogenation technologies. Hydrogenation technologies include fixed bed, ebullating bed, suspended bed, and moving bed, et al. Non⁃hydrogenation technologies include alkali metal compound treatment, selective oxidation⁃extraction/thermolysis/process intensification, electrochemical, biodesulfurization, and sodium, et al. Among these hydro⁃desulfurization technologies, fixed bed hydro⁃treating is more proper in producing residual marine fuel with the sulfur content lower than 0.5% at present. Meanwhile, to produce residual marine fuel with sulfur content lower than 0.1%, it needs to choose the low sulfur containing raw materials and/or blend oils. For non⁃hydrogenation desulfurization technologies, selective oxidation⁃ultrasound and sodium technologies can directly produce heavy fuel oil with sulfur content lower than 0.1%, while sodium desulfurization technology shows a better application prospect.
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Preparation of In⁃Situ Precipitated SOFC Composite Anode Based on Fe⁃Based Perovskite
Xu Jingsheng， Cai Hongdong， Zhang Leilei， Yao Guibin， Song Zhaoyuan
2021, 34 (1): 22-27. DOI:10.3969/j.issn.1006-396X.2021.01.004
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The Mo ions with high valence state in La_0.5Sr_0.5Fe_0.9Mo_0.1O_3-δ (LSFM) were partially substituted by trace amounts of Ni, which was found to weaken the structural stability of La_0.5Sr_0.5Fe_0.9Mo_0.1O_3-δ under reducing atmosphere. In this way, Fe⁃Ni alloy nanoparticles precipitated on the surface of the oxidized perovskite under reducing atmosphere, and a composite anode then be prepared showing improved catalytic properties, electrochemical characterizations of which were evaluated. The experimental results indicate that power densities of single cell using La_0.5Sr_0.5Fe_0.9Mo_0.07Ni_0.03O_3-δ (LSFMN0.03) as anode are 0.84 W/cm² and 0.62 W/cm² (800 ^oC) with polarization resistance of 0.35 Ω·cm² and 1.01 Ω·cm² (800 ^oC) under H₂ and CO fuels, respectively. The performances of cell with LSFMN0.03 anode are obviously higher than that of La_0.5Sr_0.5Fe_0.9Mo_0.1O_3-δ anode. The results of stability tests indicate that, the cell with LSFMN0.03 anode could maintain an excellent electrochemical stability, when the H₂ content in H₂/CO mixture fuel is more than 40%.
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A Novel GO/MoS₂ Composite Electrode： Preparation and Application in Pb(II) Adsorption
Wang Yiming， Huang Wei， Cong Yufeng
2021, 34 (1): 28-33. DOI:10.3969/j.issn.1006-396X.2021.01.005
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A new type of electrode has been prepared by composite of molybdenum disulfide (MoS2) and graphene oxide (GO), and applied in adsorbing Pb(II) in water using capacitance deionization method. The electrode was characterized by X⁃Ray Diffraction (XRD), Raman, Transmission Electron Microscopy(TEM), and Brunauer⁃Emmett⁃Teller(BET). The adsorption mechanism was investigated using X⁃ray photoelectron spectroscopy (XPS), XRD and cyclic voltammetry (CV). The results indicate that GO in the GO/MoS₂ composite could prevent aggregation of MoS2 and increase the interface of electrode with electrolyte. Besides, the absorption mechanism is proved to be the synergistic absorption effects of double electrode layer and pseudo⁃capacitance, and the former is more effective. The adsorption capacity of GO/MoS₂ composite electrode is 4 614.9 mg/g, higher than that of pure GO 1 876.9 mg/g and pure MoS2 1 175.4 mg/g, Therefore, GO/MoS₂ electrode shows superior performance in removal of Pb(II) with high concentration.
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Research on the Control Index of High Mass Concentration Flowback Fluid in Chengdao Oilfield
Lü Jiaxing， Hou Lei， Liu Fangyuan， Zhu Zhenyu， Wang Yujiang
2021, 34 (1): 34-38. DOI:10.3969/j.issn.1006-396X.2021.01.006
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The flowback fluid during oil acidizing operation process would directly enter the gathering and transportation system,resulting in deterioration or invalidation of conventional treatment agents,such as demulsifiers.The flowback fluids from the Chengdao Oilfield were divided into two types ，one is high mass concentration,the other is low mass concentration.The high mass concentration flowback fluid is transported back by the operating ships to the shore for further treatment,and the low mass concentration flowback fluid is directly discharged into the gathering and transportation system under the ground.The flowback cycle is long and affected by sea conditions. In order to reasonably estimate the amount of high mass concentration flowback fluid produced by crude oil dehydration process,this paper analyzes the factors affecting the oil⁃water separation of acidified flowback fluid.The volume of flowback fluid and indicators of water in two acidified oil wells were monitored,and thermal deposition of mixed flowback fluid and crude oil were tested. According to the demulsification effect and the water content of crude oil form the joint station, the quantified critical control index are listed as: the pH value of the water from the acidified oil well is higher than 6, the iron ion concentration is lower than 250 mg/L；and the auxiliary control index: the amount of backflow reaches 6 times higher than that of the acid liquid. An inspection method is proposed for the on⁃site operation of the flowback fluid discharging into the gathering and transportation system, properly reducing the flowback time without adding a new processing flow, which is beneficial to increase the oil well production rate and improve economic efficiency.
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Optimization of Production and Operation Parameters of New Daqing-Harbin Oil Pipeline in Alpine Region
Wei Lixin， Zheng Lilong， Li Wenzhong， Ouyang Xin， Chu Yongqiang， Liu Junbo
2021, 34 (1): 39-44. DOI:10.3969/j.issn.1006-396X.2021.01.007
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The optimization of production and operation parameters of oil pipelines can effectively reduce operation energy consumption and improve the economic benefits of pipeline transportation. Aiming at the newly⁃built Qingha oil pipeline in the high and cold regions,the production energy optimization model was established with the constraints of the minimum energy consumption in production and operation,and the constraints of temperature constraints,pressure constraints,and oil pump operating characteristics constraints.In order to improve the solution efficiency,the hybrid PSO⁃Powell algorithm is used to solve the problem.The optimization results show that after optimization,the thermal energy loss is reduced by 38.3%,the pressure energy loss is increased by 90.3%,and the total energy loss is reduced by 26.3%.The energy saving effect is obvious.
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Research of EOR Technical Measures for Natural Water Drive Thin Oil Reservoir
Li Futang， Xin Chunyan， Wu Qiong， Li Jiahui， Wang Bo
2021, 34 (1): 45-49. DOI:10.3969/j.issn.1006-396X.2021.01.008
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Nanbao shallow reservoir is a typical complex fault block reservoir. According to oil products, 60.9% of the reserves belong to conventional thin oil reservoirs. The reservoir has the geological characteristics of active marginal and bottom water, small fault block and small oil area and has come into extra high water cut stage. Because of low water flooding production rate, it is urgent to carry out technical research to further improve reservoir recovery. The paper regarded the reservoir of NmⅡ4② layer in Gao 63⁃10 block as a typical unit. According to the geological characteristics of small oil sands area and sufficient natural energy, the paper puts forward a new oil drive method named deep huff and puff. Based on the oil well，this new oil drive method can improve the swept volume and flushing efficiency and has the advantages of small scale, low investment and flexible adjustment. It provides technical reference for development and adjustment of similar reservoirs at extra⁃high water cut stage.
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Calibration of Grid Upscaling Effect by Segmental Translation Phase Permeability Curve Method
Zhang Jicheng， Yan Zhiming， Fan Jiale， Bao Zhikui
2021, 34 (1): 50-57. DOI:10.3969/j.issn.1006-396X.2021.01.009
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Grid upscaling is to keep the reservoir physical properties and seepage characteristics of the two models as same as possible before and after upscaling. Thus, the model after upscaling can achieve the same development effect as before upscaling. The permeability is upscaled by harmonic average and arithmetic average. It's found that the relationship curve between recovery degree and water cut after upscaling is different from that before upscaling. Based on reservoir engineering theory, a functional relationship between slope and intercept of Kro/Krw⁃Sw relationship curve and slope and intercept of water⁃oil ratio and recovery relationship curve is derived. Therefore, the phase permeability curve after upscaling can be deduced back. It's found that there is a linear relationship between the displacement distance of the phase permeability curve and the intercept of the fitting line of the water⁃oil ratio curve and the recovery degree curve. The displacement distance of the phase permeability curve can be calculated. The phase translation law is verified by using actual oilfield data. The error of water⁃oil ratio and recovery degree curve between after translation and before coarsening is 3.16%, and the precision is high.
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Prediction of Corrosion Rate of Casing Steel Containing CO₂/H₂S Based on Multiple Linear Regression
Chen Hao， Yang Erlong， Ji Dawei， Li Yilin， Zhao Liang， Yang Yunqing
2021, 34 (1): 58-62. DOI:10.3969/j.issn.1006-396X.2021.01.010
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At present,the research on the corrosion rate of the oil casing in the wellbore containing CO2/H2S is the current research hot spot in the field of corrosion and protection. In order to accurately study the corrosion situation of the oil casing and predict the corrosion rate,the weight loss method was first adopted to study the corrosion rate under different corrosion time,and the experimental results were fitted. Secondly, combining the research results of this paper with the previous research content,the Table Curve 3D software for multiple regression was used to determine the corrosion rate prediction model.The results show that the corrosion rate decreases continuously with the increase of time.The fitting of the experimental results R2 is 0.989 3,the error is small.The model established by multiple regression can accurately predict the corrosion rate and the error is within 5%,which meets the accuracy requirements,and can lay the foundation for the on⁃site oil and gas well safety evaluation.
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Research Progress of Natural Gas Dehydration with Supersonic Separator
Dai Guohua， Sang Jun， Wan Yufei
2021, 34 (1): 63-71. DOI:10.3969/j.issn.1006-396X.2021.01.011
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The research and application of supersonic separator (3S for short) have been extensively investigated and applied overseas, but is not yet adequate in China. Numerous theoretical studies have been conducted, which mainly focus on the swirl flow, the internal flow and the condensation process. However, experimental results, specially on condensation and separation mechanism of high⁃pressure natural gas are rarely reported, as well as industrial and field test. A lot of work has been carried out in structural design, mainly focusing on comparative analysis, and no feasible structural design strategies have been proposed. The basic research on droplet condensation is even rarer. At present, the process is mainly characterized by CNT and Gyamathy model. In pratical conditions, an appropriate model needs to be selected for calculation and analysis according to the characteristics of various modified models. In order to improve the efficiencies of gas condensation and gas⁃liquid separation, the next research should focus on the effect of the main factors, such as the inlet temperature & pressure, supersaturation, the converter installation position, the supersonic nozzle structure, on the condensation process, so as to the experimental researches on the high⁃pressure natural gas supersonic separation. The industrialization of domestic supersonic separators will provide an effective tools to the dehydration, deacidification, de⁃heavy hydrocarbon before pipelining for the limited offshore platform.
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Effect of Dissolved⁃Air Flotation on Flow Field Characteristics of Produced Water in Settlement Separation Process
Zhang Jing， Pang Yanping， Li Zhimin， Wang Zhihua
2021, 34 (1): 72-79. DOI:10.3969/j.issn.1006-396X.2021.01.012
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Based on the dissolved⁃air flotation process, a multiphase flow mixture model numerical simulation was established to simulate the pressure field distribution, particles trace characteristics and the removal effect of oil and suspended matter in the process of settlement separation of produced water by air flotation, the influence of air flotation on the characteristics of the settlement separation flow field of produced water is revealed by comparing with the characteristics of conventional gravity settlement separation. The results indicate that the more stable pressure field distribution is obtained by the sedimentation with dissolved⁃air flotation through adapting the change of treatment amount, and relatively stable and orderly motion tracks of oil droplets and suspended particles with uniform distribution in the flow field are obtained by avoiding vortexing. The removal rates of oil and suspended solids under simulated conditions are increased by 8%~11% compared with the conventional gravity sedimentation separation, and the improvement of the settlement separation effect of produced water was effectively ensured. The construction of the adaptability of air flotation process and the basis of improving the efficiency of produced water treatment are provided by the understanding of the flow field characteristics in the settlement separation of air flotation.
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The Spreading Behavior of Oil Droplets in Water on Different Wettability Surfaces
Han Yunrui， Huo Fuyong， Zhu Guocheng， Du Xin， Chi Kun， He Limin
2021, 34 (1): 80-87. DOI:10.3969/j.issn.1006-396X.2021.01.013
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The spread behaviors of the underwater oil droplet on smooth brass substrate were studied using high⁃speed microscopic imaging technology. Chemical and physical modifications were made on the surface of the brass sheet to change its surface properties, and the controllable regulation of superoleophilic–superoleophobic wettability gradient of the surface was achieved successfully. The spreading length and contact angle of the oil droplet rising to different modified surfaces were tested. Different from that in air condition, influence of water surrounding the oil droplet must be considered, which is complicated in water. In this work, on the basis of the energy conservation mechanism, quantitative relationship among the eigenvalues for the spreading behaviors of the oil droplet rising to the surfaces, such as droplet dimensionless spreading length, the droplet impact velocity, droplet size, droplet properties, viscosity of the water and surface wettability, were obtained. An optimized spreading dynamic model was constructed to describe the spreading behaviors of underwater oil droplets on surfaces with different wetting properties, to give support for the design of new oil⁃water separation equipment.
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Temperature Drop and Transportation Scheme of Submarine Pipeline Considering Overburden Heat Storage
Wan Yufei， Liu Chunyu， Li Liwan， Huang Yan， Hao Ming， Wang Wenguang
2021, 34 (1): 88-94. DOI:10.3969/j.issn.1006-396X.2021.01.014
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The temperature profile has a decisive influence on the timing of the replacement and blending water of subsea pipeline, as well as smooth restart after shutdown. For a quantitative evaluation on the delay effect resulted from consideration heat storage and dissipation of cover layers, the energy storage capacity of each layer is analyzed theoretically, and the influence of heat storage of steel pipe and soil on the temperature drop of different types of pipelines after shutdown is simulated and calculated. Taking two practical pipelines in Bohai Sea as an example, the transportation scheme is optimized. The results show that the total stored heat by steel is about half of the heat of the crude oil in oil pipeline, 1/4 of the water in water pipeline and 4~16 times of the natural gas in gas pipeline, which depends on the system's pressure. The heat storage and heat dissipation of steel pipe and soil can delay the temperature drop of fluid shutdown. For the insulation pipeline, the stored heat by steel makes a different on temperature drop, while for the non⁃insulation pipeline, the heat by soil has a great impact on temperature profile. Within the crude oil pipeline in Bohai Bay of China, there is about a 3.5~13.5 ℃ temperature increase at the outlet of pipeline when consideration the heat storage and dissipation of cover layers. When the GOR is greater than 10, there is a particularly obvious effect on the temperature drop when shutdown, which is conducive for a safe and smooth transportation. Considering the influence of heat storage and heat dissipation of soil or steel pipe on the temperature drop of shutdown, the water mixing transportation can be delayed or cancelled.
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