Graphitic carbon nitride (g⁃C3N4) possesses a unique two⁃dimensional structure, which is used as a kind of excellent non⁃metallic semiconductor photocatalysts, owing to its visible light absorption, adjustable energy band grade, high stability, and so on. This review focus on recent research results and progress, and modification and catalytic mechanism related to photocatalysts are summarized based on microstructure changing, elemental doping, semiconductor loading, and multiphase composite of g⁃C3N4. Finally, the review presents the viewpoint for the development of g⁃C3N4⁃based photocatalytic performance.
Self⁃assembled monolayer films of i⁃salicylaldehyde⁃o⁃phenylenediamine (A) and di⁃o⁃vanillin⁃o⁃phenylenediamine (B) were fabricated respectively on copper electrode surface by molecular self⁃assembled process. The corrosion inhibition performance of the Schiff bases self⁃assembled films (SAMs) in 3.5% NaCl solution was examined by electrochemical methods. The best corrosion inhibition rate of Schiff base A reached to 94.06% with the concentration of 10 mmol/L and assembly time of 4 h at 25 ℃. For Schiff base B, the best corrosion inhibition rate reached to 96.62% with the concentration of 15 mmol/L and assembly time of 6 h at 25 ℃. The results showed that two inhibitors had good corrosion inhibition performance, and the inhibition effect of B was better than that of A.
In this paper,three types of RE⁃NaY zeolites modified by La,Ce,and Nd were prepared by liquid⁃phase ion exchange method. The influence of rare earth ions on the acidity and catalytic performance of zeolites was investigated. The X⁃ray diffraction (XRD) and N2 adsorption isotherms were used to characterize the structure and texture of the samples. The in situ FTIR spectroscopy was used to study the acidity of the molecular sieves. The Dagang light diesel oil was used as the raw material to evaluate the catalytic cracking microreaction activity of the molecular sieves. The results confirmed that Nd ions with smaller ion radii migrated more easily from the super cage into the SOD cage than Ce and La ions,resulting in the most B⁃acid center in the Nd⁃NaY sieve super cage with a larger pore size. So that it exhibited the best catalytic cracking activity. Therefore,it is proved that the modification of rare earth ions with a smaller ionic radius can effectively increase the utilization rate of supercage of Y zeolite in the catalytic cracking process.
This article simulated three mortar systems including mineral filler⁃asphalt,mineral filler⁃emulsified asphalt residue and cement⁃emulsified asphalt residue in cold recycled mixture with emulsified asphalt. The results show that cement⁃emulsified asphalt residue mortar owns higher modulus than the other two mortars because of cement hydration. The change of modulus and phase angle is different from that of ordinary mineral powder⁃asphalt mortar and mineral powder⁃emulsified asphalt mortar, and does not change linearly monotonously with powder⁃to⁃binder ratio. At the same time, the interface adhesive ability of cement⁃ emulsified asphalt residue is similar to that of the mineral filler⁃asphalt mortar, and much higher than that of the mineral filler⁃emulsified asphalt residue mortar in a lower filler dosage. In the process of mixture production, emulsified asphalt provides the initial stability of the mixture, and cement hydration and the formation of composite mortar system are the guarantee of the final cold recycled mixture strength.
To solve the problem of polymer plugging of polymer injection well area in the bohai sea, a kind of efficient composite depolymerization additive is screened in the paper. Laboratory experiments show that the degradation rate of 5 000 mg/L polymer solution can reach more than 99%, and the polymer scale samples with crude oil from oil well in Bohai can be degraded in 72 h because of the low interfacial tension and good oil washing effecthigh effect of washing oil. Meanwhile, the high chelating ability of this depolymerization additive is good for the depolymerization of the crosslinking polymer, and the degradation progress can be as less as 3 h.The plug removal application in one oil well well shows that the efficient depolymerization additive has remarkable capacity of enhancing liquid and oil.
After the XQ⁃45 block entering the multiple rounds of steam huff and puff, it is affected by edge water, faults, reservoir properties and other factors. The remaining oil distribution is complex, and steam huff and puff effect is getting worse. According to the reservoir dynamic data, the 79 wells in this block are divided into different types of heavy oil wells according to the remaining oil saturation parameters. Among them, the number of remaining oil wells affected by edge water is more than 22. As the edge water proceeds along the high⁃permeability layer to the oil well, the water content rises quickly and easily causes flooding. To further improve the effect of steam huff and puff, aim at the unutilized section in the edge water affected oil well, and take the single⁃layer steam huff and puff mode to study the optimization of steam huff and puff parameters affected by edge water. Through extract single⁃well geological model and compare different steam injection programs, the best program is selected: steam injection volume is 100 t/m, the oil steam ratio maintain at 0.2 t/t or more, obtain the maximum amount of oil production. The results show that cycle steam injection volume is 100 t/m, the oil production is the largest in the third cycle, and the sweep radius of steam reaches the maximum. After 5 rounds of steam huff and puff, cumulative steam injection volume is 3 700 t, cumulative liquid production is 4 500 t, cumulative oil production is 738.65 t, and the program implementation effect is getting better.
Fractal theory provides an effective means for quantitative characterization of reservoir pore structure, while the pore structure of the tight sandstone reservoir is complicated. It needs further study that whether the conventional characterization of the fractal features of pore structure is applicable to tight sandstone reservoir or not. In this paper, present fractal characterization methods of pore structure are systematically sorted out, the applicability of each method is evaluated based on mercury injection curves of 5 tight sandstone samples, and the fractal characteristics of tight sandstone reservoir are studied. The results show that the fractal definition method can effectively characterize the fractal features of pore structure of tight sandstone, while the He Chengzu method is only applicable to tight reservoirs with permeability higher than 0.1×10-3 μm2 and the Li Kewen method is only applicable to tight reservoirs with permeability lower than 0.1×10-3 μm2, and the Brooks⁃Corey method are completely not applicable to tight sandstone reservoirs. Tight sandstone reservoir has fractal characteristics in the whole pore radius region, and no fractal features exist. Fractal dimension is an important parameter in reservoir evaluation. And the higher the fractal dimension, the worse the physical properties of reservoir, the smaller the average pore radius, the higher the displacement pressure and the higher the bound water saturation.
Based on the thin section, grain size, sedimentary structure, vertical sequence, curvature calculation results and log response characteristics of the core in the target interval of the study area, it is shown that typical braided river deposits are developed in the VI sand formation of Y Group in the study area. According to the results of thin slice identification and core analysis, the sedimentary microfacies characteristics of the target interval of the study area are summarized. The relationship between sedimentary microfacies and well logging response is established and applied to the division of single well sedimentary facies. Refer to the recent research results about braided river, both in China and abroad, we propose a braided river sedimentary model of VI sand group of Y Group in Sudan P Oilfield, based on the distribution of braided river in the target layer both on plane and profile, which provides a reliable geological basis for the preparation of the next P oilfield development program.
In view of the weak research on the characteristics of geotemperature⁃pressure system in the northern part of Dongpu Depression, based on the measurements of ground temperature and pressure, the characteristics of geotemperature field, geopressure field and temperature⁃pressure system in the northern part of Dongpu depression are analyzed by T⁃P system theory. Combined with the structure distribution pattern, their effects on hydrocarbon distribution have been analyzed. The study demonstrates that the temperature gradient in north part of Dongpu depression is high, the sag zone has the characteristics of deep buried and high geotemperature, which is beneficial to the maturity of source rocks and the formation of hydrocarbon in the sag zone. The deep overpressure could be as the important motivating force for hydrocarbon migration. In vertical, the T⁃P system includes static pressure geothermal⁃geopressure system and overpressure complex geothermal⁃geopressure system. The lateral T⁃P system can be divided into 5 subareas, namely, HTHP, NTHP, HTNP, NTNP and LTNP, and the low⁃energy NTNP is the place where petroleum mainly accumulates. Different from other hydrocarbon rich depressions in the Bohai bay bain, due to the development of gypsum⁃salt cap rock, a large amount of hydrocarbon has accumulated in the high⁃energy NTHP.
Aiming at the problems such as the large decline in water flooding production, the poor utilization of reservoirs, and the low formation pressure in the development of North First and Second Section West, the potential of well pattern adjustment in this area was studied. Combined with several reasons that affect the development effect of the block, it is analyzed that it is difficult to effectively improve the overall development status of the block by relying only on regular dynamic adjustment measures. Through the implementation of layered well pattern adjustment, the daily production volume of the entire area is increased by 5 640 t and the daily oil production is increased by 197 t. The water content was basically stable, the oil production rate rose to 0.60%, the flow pressure subsidence was restored, and the overall development of the block was effectively improved. As of August 2017, it has accumulatively increased oil by 20.5×104 t, and it is expected to increase oil recovery by more than 2.0 percentage points. Well network encryption and subdivision layer system adjustments have achieved significant effects, which solved the problem of poor level of use and improved the ultimate recovery rate.
Corrosion of oil and gas pipeline steel in the marine environment is one of the important factors that damage the integrity of oil and gas pipelines. The effects of different HCO〖_(3)^-〗 concentrations in simulated ocean solution on the electrochemical corrosion behavior of X100 steel were investigated by using potentiodynamic polarization and AC impedance technique. The results showed that the corrosion current density, the corrosion pits number and area of X100 steel increased with increasing of HCO〖_(3)^-〗 ion concentration. In addition, when HCO〖_(3)^-〗concentration was 0.1 and 0.5 mol/L, transition passivation zone appeared in the anodic polarization curve of X100 steel, and unstable product film was formed on the metal surface.
Using waxy crude oil and pure water as the working material, several groups of W/O emulsions with different microscopic droplet distributions were prepared. With microscope and focused beam reflectance measurement instrument, the size and distribution of the dispersed droplets in emulsion were observed and measured. Furthermore, the effect of droplet distribution on the rheology and wax precipitation characteristics of emulsion was discussed. The results show that with the increase of water content, the apparent viscosity of W/O emulsion will be higher, the yield stress, gel point and wax appearance temperature will also increase, while the constant stress will show a gradually decreasing trendency. The phase transition point of Daqing waxy crude oil is about 60% water content.
Three⁃dimensional finite element model of buried casing is established using ANSYS software. Through laboratory tests, the relationship between the stress within the center of buried casing and the load on the ground, and the stress distribution in the direction of casing length under different loads is analyzed,respectively. Finally, a three⁃dimensional finite element model is established according to several casing cases in an oilfield. The magnitude of the load on the ground is obtained when the casing reaches the yield strength. The research results can provide a certain reference for the safety protection of pipelines and casing.
The effect of friction to dry gas seal performance can’t be ignored under the condition of high parameter. Based on the structure characteristics of the sealing system and end⁃face, it was established the calculative model of lubricating gas film, used IC⁃EM to divide the grid. Then, conducted numerical simulation to get gas film pressure distribution and velocity distribution by using Fluent software. Finally, it calculated the friction coefficient of lubricating film by the law of Newton internal friction. The result of research shows that the friction coefficient of the lubricating film increases with the increase of the rotational speed, and it decreases with the increase of the medium pressure and the average film thickness in the groove parameters remain unchanged case. When the operating parameters are unchanged, the film friction coefficient increases with the increase of the root diameter, decreases with the increase of the number of grooves and the depth of the groove, and in 75° to 76° spiral angle range is relatively stable.
Due to large fluctuation on average COT temperature in two ethylene cracking furnace named EF⁃111M and EF⁃111N of No.1 petrochemical plant of PetroChina Daqing petrochemical company, an advanced control system of average COT temperature for the furnaces is designed and developed. Firstly, based on the existing problem of conventional control strategy, the advanced control strategy of average COT is designed. In addition, the non⁃minimal state space model predictive control (NMSSMPC) is used as the design of the average COT temperature controller. Finally, the developed advanced control system of average COT temperature is applied to M# and N# furnace of Daqing petrochemical company. Compared with the conventional control strategy, standard deviation between measurement and set⁃point of COT temperature in M# furnace decreases from 1.24 ℃ to 0.57 ℃ with the advanced control strategy. And the standard deviation of average COT temperature in N# furnace decreases from 1.84 ℃ to 0.72 ℃. The standard deviation of average COT reduces by 54.03% and 60.87% for M# and N# furnace, respectively. It can achieve the expected goal to remain average COT within 1 ℃.
Cryogenic liquefied natural gas (LNG) tank container is the most typical equipment for transporting liquefied natural gas. It has the advantages of high mobility and flexibility. Due to the complex operation conditions of tank containers, the medium inside the tank is flammable and explosive and needs to be stored in low temperature environment, and the requirement for the cold insulation performance of the container is high. Based on the finite element theory and the actual working conditions, this paper calculates and analyzes the heat leakage problem along the axial direction of the top inlet pipe of LNG tank container by using ANSYS software, and it is found that the heat flux along the axial direction is high. The heat in the external environment is easily transferred into the tank along the pipeline and the heat transfer rate is fast. The broken bridge structure is introduced into the optimization design of the pipeline and an improved scheme is put forward to achieve the effect of heat flow blocking.
