Non⁃ionic surfactants, fluorinated cationic surfactants, and fluorocarbon polymers have been evaluated for their ability to alter wettability and injectivity in tight sandstone reservoirs through contact angle tests and injectability tests. The results showed that, compared with other chemical agents, the fluorocarbon polymer CRS⁃850 had better gas wetting inversion effect, and the contact angle of the core surface increases from 45.6° to 92.1°; the self⁃absorption of salt water before wettability changing was 0.360 8 g, the self⁃absorption after treatment dropped to 0.020 6 g, the core self⁃aspiration decreased by 98.85%, and the max self⁃suction rate decreased from 0.053 g/min to 0.002 g/min. The wet reversal agent increased the liquid⁃phase percolation capacity of the coreand the gas⁃driving permeation rate significantly, and the recovery effect of core gas drive permeability is remarkable, which increases by 501.69% to 673.91% on the basis of the gas flooding brine, indicating that the gas⁃wetting reverser has beneficial to remove liquid⁃phase damage in tight sandstone reservoirs.

Aiming at the problems of large amount of oilfield waterflooding technology, long measuring and adjusting period, low precision of measuring and measuring, and severe influence of well inclination, the mechanical stratified water injection technology is studied. The technology for the first time adopts hydraulic machinery style control, and integrates intelligent downhole monitoring, automatic tool control and other characteristics, to achieve a real⁃time monitoring, on⁃line measurement functions. The successful application of this technology in Well X6, an oil field in Bohai sea in June 2017 shows that the stratified water injection tool has reliable performance, on⁃line real⁃time measurement and adjustment, and improves the measuring and adjusting efficiency. It can be applied to acidizing operations, interwell tracer and other operations, and provides a new technical idea for stratified water injection development technology in Bohai oilfield.

In order to further improve the recovery of oil after binary composite flooding in offshore oil fields,based on the development contradiction existing after the binary flooding,combined with the indoor physical simulation experiment,three different combinations of oil displacement systems were designed on the basis of conventional oil displacement agents. According to the characteristics of the reservoir after the binary flooding,three kinds of high concentration polymer flooding,high concentration polymer + two yuan and heterogeneous phase were proposed and compared with the experiment. The results showed that the three experimental schemes showed different degrees of secondary decline in water,the shunt rate of the high permeability layer decreased,and the shunt rate of the medium and low permeability layer increased.The recovery rate of experiment was 13.55%,10.93% and 16.05%,respectively.It provides technical support for subsequent profile optimization and individual well personalized design,which lays the foundation for the completion of a set of recovery technology method system after a set of two yuan flooding.

Aiming at the demanding requirements of sealing performance in ultra⁃deep oil and gas wells, a double main sealing structure consisting of conical surface to conical surface and cylindrical surface to spherical surface was designed based on the special thread sealing mechanism. Using numerical simulation method, the changes of contact stress and the contact length of the sealing surface under the four conditions of tensile, compression, tension and internal pressure, tension and internal and external pressures were analyzed. The sealing performance of threaded joints under the ultimate load was studied, and the change rule of sealing capacity with different loads was obtained. The full⁃scale test results show that the sealing performance of the double main seal premium threaded joint meets the application requirements.

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.

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.

The two zones of water injection after X well repair in Bozhong 25⁃1 oilfield are confronted with two major problems. First, the injection pressure difference between two layers is 18 MPa, and secondly, the application of steel wire or coiled tubing is used to replace the horizon. The operation cycle is long and the cost is high. In order to solve the above problem, a new type of non⁃throwing fishing periodic water injection technology is applied, and the underground water injection level and water injection volume are adjusted by surface hydraulic control. The optimum design of sand control pipe string and water injection pipe string is matched to replace repeated steel wire operation. The problem has been solved, which guarantees the safety of water injection operation in high pressure differential layer, and saves 100% of the time and cost of steel wire allocation.

In order to realize the efficient development of the oilfield,it is needed to evaluate the productivity of the reservoir. According to the structure of horizontal well, the form of fracture and the distance of fracture, combined with the theory of seepage mechanics, a well test analysis model for multistage fractured horizontal wells considering wellbore storage and skin factor is established. A typical curve fitting chart of pressure and derivative is obtained, and a well testing interpretation software system based on the theoretical plate is developed. Based on the well test interpretation software system compiled by the theoretical plate, the IPR curve and the production decline curve are plotted by using multistage fracturing horizontal well test interpretation software.The results show that under the same production conditions, the influence of fracture distance and crack skin factor on productivity is less than the effect of crack half length on productivity. According to the curve of production flow rate with bottomhole flow at different production stages and the curve of output with production time at different bottomhole flow pressures, and the production capacity is predicted and evaluated at different stages of fracturing horizontal wells. It provides a strong guarantee for the efficient development of multistage fracturing horizontal wells.

The enhanced oil recovery technology of ASG (alkali, surfactant and nitrogen) composite foam and water alternating injection was studied in high temperature and high salinity low permeability reservoir. The ASG foam and water alternating injection experiments were carried out through indoor flooding experiments, and compared with water flooding nitrogen flooding and surfactant flooding. The results show that the enhanced oil recovery of the method adopted by this study is 16.61%, 10.26% and 9.21%, respectively, compared with water flooding, nitrogen flooding and surfactant flooding technology. Experimental study on injection parameters optimization of ASG foam and water alternating injection is carried out, and the parameters such as slug size, injection rate and gas fluid ratio of ASG composite foam are optimized by bench scale displacement test. The results show that under the condition of the same foam injection volume (1.2 times the pore volume), the effect of foam slug injection with 0.4 times pore volume is best. The foam injection rate has an optimum value of 1.5 mL/min. When the injection rate is too low, less foam is produced, gasliquid separation is easy to occur, and the blocking effect is poor. When the injection rate is too high, the size of the bubble is different, and it is easy to cause the bubble to merge, causing the bubble to burst, and at the same time, it is easy to cause the shear defoaming of the foam. When the gas fluid ratio is 3∶1, 2∶1 and 1.5∶1, respectively, the recovery rate is 2.04% higher than that of the single gas fluid ratio.

Passes temperature balance system of ethylene cracking furnace is a multivariable, nonlinear, strong coupling complicated process. Under the circumstances of multi-passes, the complexity and uncertainty of system could be increased by using difference control method. In view of the above problems, an improved difference control scheme was proposed, which processes all the passes as a whole. This scheme avoided employing the difference control technique reiteratively. The controller structure is simple and easy to be implemented. Simulation experiment shows that the improved difference control method is reasonable and has good tracking performance.

When acoustic method was used to leak detection, external interference (operation of compressor and valve, pipeline knocking, etc.) should be distinguished with acoustic leak signals to improve the accuracy of leak detection and reduce false alarm. The technologies of extracting wave characteristics were summarized. The acoustic leak signals and interfering signals were gathered by a high pressure and long distance leak test loop to analyze characteristics of time domain, frequency domain and time-frequency domain. The main characteristics of time domain were mean value, root mean square value, kurtosis, skewness and correlation function, etc. Frequency spectrum analysis and power spectrum density were adopted to analyze the feature of frequency domain, while short time Fourier transform was used to process time-frequency analysis. The results show that the external interference can be removed effectively by the characteristics of time domain, frequency domain and time-frequency domain.

Disodium nonylphenol polyoxyethylene monoester sulfoitaconate was synthesized through the esterification and sulfonation reactions using nonylphenol polyoxyethylene ester, itaconic acid and sodium sufite as raw materials. The effects of reaction temperature and molar ratios of reactants on reaction were investigated. And the production was applied to styrene-acrylic emulsion polymerization as new emulsifier,which compared with the traditional emulsifier. The results show that the emulsifier was obtained under the condition of n(NPEO (10))∶n(IA)=1.00∶1.06,n(IA)∶n(Na2SO3)=1.00∶1.06, reaction temperature 120 ℃ and 90 ℃. A stable styrene-acrylic emulsion was got with the new emulsifier dosage of 2.4%, the dosage of emulsifier is 20% less when the traditional emulsifier was replaced by new product.

Montmorillonite was changed to organophilic with the hexadecyltrimethy lammonium bromide and dodecyl trimethy ammonium bromides, and organic montmorillonite was obtained. OMMT/E-51 composite modification for waterborne polyurethane was prepared. The effect of OMMT, DMPA and E-51 mass percentage on OMMT/E-51 composite modificationfor waterborne polyurethane were studied. The results show that the the mass fraction of OMMT was 1.5%, the mass fraction of DMPA was 4.0%，the mass fraction of E-51 was 4.0%，the emulsion and adhesive film possessed a good performance, the water absorption is 5.9%, the water contact angle is 98°, the tensile strength is 32 MPa, the elongation at break is 571%. 

Physical and chemical properties and poor quality of sulfolane was analysed, and the effect of several additives on the thermal stability of sulfolane was studied. An optimized experiment condition, water-vapour absorption, nitrogen protection, 220 ℃ and 6 h were set. Four amine alcohols were used as additives. The thermal stability of sulfolane was evaluated indirectly by the generation amount of BaSO4, and finally by the content of released SO2. The less content of released SO2 indicated the better effect of additives on restraining sulfolane thermal decomposition. The different quantity of addition of every additive are investigated, certain effect of all four additives can be observed, in which, quantity of addition of HW-D-01 at 0.04% lead to a best effect on thermal stability of sulfolane.

Xanthan gum(XG)/2-acrylamido-2-methylpropanesulfonic acid(AMPS)/bentonite composite water plugging agent for oil field was synthesized by aqueous solution polymerization. Effect of the amount of AMPS, bentonite, crosslinking agent and initiator on waterabsorption capacity of water shutoff agent were investigated. Waterabsorbency and water retaining rate of the water shutoff agent at different temperature were tested. NaCl concentration on waterabsorption capacity of water shutoff agent were researched. The results show that the optimum process conditions were obtained as follows: w(bentonite) is 15％, w(AMPS) is 3％, w(crosslinking agent) is 2％, w(initiator) is 2.5%, and reaction temperature is 40 ℃ for 4 hours. Under the optimum technological conditions, with the environmental temperature of 20 ℃, waterabsorbency for deionized water and 0.9％ NaCl solution of the water plugging agent for oil field are respectively 1 677 g/g,165 g/g. With the environmental temperature of 80 ℃, waterabsorbency for deionized water of the water plugging agent for oil field are respectively 1 590 g/g,within 12 h can hold water over 20%, which possessed a good thermal stability and salt tolerance.

The structural style and working principle of the external floating roof tank's automatic breather valve were briefly introduced.Fixed the analogical standard of the oil vapour space between the factory end and the floating plate when it was unrisen.The volume ofthe roof tank decides the heat affecting volume calculate the tank throughtout and the breathing area of the breather valve.According to the fluid steady flow mathematical equation,deduced the height computing formula of petroleum production flowing into the automatic breather valve.Definite the design height that the valve handle must possess when the breathing area was given.And then analyze the oil spill reasons of the established oil tanks,which may be caused by the lacking of breathing area or the design height of valve handle,and the problems must pay attention to in future design.

One-dimensional,non-isothermal gas flow model was adopted to simulate the transient phenomena in gas transmission pipelines.The model was coupled with SRK,PR,BWRS and AGA8 equations of state respectively and solved with the method of characteristics.The results show that there is little difference of pressure and flowrate between the four equations of state,and slice temperature difference existed which is adoptable in practical application.The calculation speed varied,therefore,when selecting the equations of state the balance between speed and accuracy demand in projects should be considered.

Based on different selection of the basic parameters, including pressure (p), enthalpy (H), density (ρ), entropy (s) and flow velocity (u), the traditional conservative model of gas transmission pipelines was transformed into 3 types: pρu, pHu and psu model. The method of characteristics was adopted to solve the above three model. The fast transient caused by instantly opening and closing valves in the gas transmission experimental pipeline was simulated with the three models respectively. The results show that the simulation process of the gas pipeline is not sensitive to the selection of the basic parameters. Comparatively, the pHu model owned a slice advantage on accuracy and computing speed over the other two models.

A numerical model was developed to simulate the three-phase flow with condensation of the mixture of methane (CH ₄), water vapor (H ₂O) and nonane (n-C ₉H ₂₀). Using this model the condensing flow of methane with saturated water vapor and nonane vapor in a convergent-divergent nozzle were investigated. The result shows that in this three-phase flow, the nucleation position of nonane vapor is 0.05 m downstream of that of water vapor, which is a result of the different thermo-physical properties of H ₂O and n-C ₉H ₂₀. With the inlet pressure rises, the supercooling leading to nucleation, the nucleation rate, the number of liquid droplets and the mass fraction of liquid phase decrease for both water vapor and nonane vapor. The result also indicates that in the three-phase flow, the latent heat released during the condensation processes of water vapor and nonane vapor changes each other's supercooling. As a result the condensation processes of water vapor and nonane vapor are weakened.