A visible⁃light induced strategy for C-C bond cleavage, amination of cyclobutanols was reported. The key alkoxy radicals were generated by employing inexpensive cerium catalyst, though charge transfer under visible⁃light irradiation which would undergo a selective β⁃scission and trapped by DBAD to afford hexahydropyridazine derivatives effectively.This reaction combines visible light and inexpensive cerium salts to develop a general practical strategy for the selective carbon⁃carbon bond cleavage and functionalization of ketones. Under operationally simple conditions, cyclobutanone compounds can be successfully converted into universal chemical structural units. Provides a nitrogen⁃containing compound while enriching the carbon⁃carbon bond breaking conversion method.
HUSY/ZSM⁃5 composite zeolite was synthesized by hydrothermal crystallization, and the structure, acidity and morphology were characterized by X⁃ray diffraction (XRD), N2 adsorption⁃desorption, NH3⁃TPD and scanning electron microscope (SEM) and pyridine infrared(Py⁃FTIR). Epoxidized soybean oil was synthesized using solvent⁃free method, and the catalytic activity of HUSY, HUSY+ZSM⁃5 mechanical mixture and HUSY/ZSM⁃5 for the epoxidation of soybean oil was compared, and the composite zeolite HUSY/ZSM⁃5 showed the best catalytic performance. The optimum conditions for the synthesis of epoxy soybean oil were as follows: 20 mL of soybean oil , 16 mL of 30% hydrogen peroxide, 4.0 mL of acetic acid, 3 g of catalyst. Epoxidized soybean oil with an acid value of 0.46 mg/g and an epoxy value of 5.60% was obtained after reaction at 70 ℃ for 4 h. The product was characterized by FT⁃IR, 1H⁃NMR, and 13C⁃ NMR.
The main development direction of helicopter main reducer lubricating oil is to improve it’s load capacity by increasing the viscosity of base oil and using new additives, and increase the reliability of main reducer. On the basis of summarizing the research progress of the helicopter main reducer lubricating oil at home and abroad, this paper points out that our country should develop 9⁃centistokes main reducer synthetic lubricating oil which meets the requirements of MIL⁃PRF⁃32538, and strengthen the research on the lubricating theory and using performance evaluation equipment of aviation lubricating oil so as to promote the adaptability of aviation oil and aviation equipment of our country.
After screening the typical relative permeability curves of thin and poor reservoirs in Xing 6 area,the flow coefficient is used as the weight coefficient to compound the normalized curves of single layer, and the composite relative permeability curves are obtained. The study of composite relative permeability curve shows that thin and poor reservoirs in Xing 6 area have the characteristics of residual oil saturation, low irreducible water saturation, low oil displacement efficiency and narrow common permeability area. According to the relative permeability curve, the water cut and recovery degree are calculated. The results show that the relationship curve between water cut and recovery degree can be divided into two types: convex and S. By studying the relationship curves between displacement efficiency and permeability, crude oil viscosity and displacement pressure gradient of thin and poor reservoirs in Xing6 area, it can be seen that displacement efficiency increases with the increase of permeability and displacement pressure gradient, and decreases with the increase of formation crude oil viscosity. The correlation analysis between oil displacement efficiency and micro⁃pore parameters shows that the correlation coefficient between pore radius and oil displacement efficiency is the smallest, only 0.090. The correlation coefficient between displacement efficiency and throat radius is 0.437. The results show that the effect of pore radius on oil displacement efficiency is small in micro pore structure parameters, and the effect of throat radius and pore throat ratio on oil displacement efficiency is greater.
The development effect of polymer flooding composite well network adjustment technology is studied through physics experiment simulation, and the development effect of oil displacement and the distribution of remaining oil are analyzed from macroscopic and microscopic aspects. The micro⁃electrode technology was applied to the macroscopic physics experiment to study the development effect and residual oil distribution of the polymer flooding composite well network adjustment technology. The microscopic physics experiment applied nuclear magnetic resonance technology to study the microscopic distribution of residual oil in the high and low permeability core pores before and after polymer flooding. The experimental results show that by changing the injection⁃production well network system during polymer flooding, on the one hand, it can effectively improve the unevenness of the displacement and expand the swept volume. On the other hand, it can improve the profile, increase the macropore production in the middle and low permeability layers during subsequent water flooding. At the same time, due to the reduction of the injection⁃production well spacing after the adjustment of the well pattern, it is possible to increase the oil production while reducing the injection amount. After the end of the displacement, the remaining oil is mainly distributed in the areas where the middle and low permeability layers are not affected, as well as the small pores in the low permeability layer.
The degassing of crude oil in the formation will increase the seepage resistance,which seriously affects the development effect of low permeability reservoirs.This paper takes a low permeability reservoir in Weicheng as an example,using steady state water flooding test method to explore the effect of oil viscosity change on the oil water two⁃phase threshold pressure gradient,and study the effect of threshold pressure gradient on the effective displacement pressure difference in low permeability reservoirs.The results show that the threshold pressure gradient increases with the increase of oil viscosity after oil degassing,which results in the decrease of effective displacement pressure difference between wells.When the injection and production pressure difference is small,it is difficult to establish effective displacement.At the same time, some countermeasures are put forward to deal with this problem.The research results are of guiding significance for the design of injection⁃production well pattern and the later adjustment in low permeability reservoirs.
In view of the problems existing in the development of the second⁃class reservoirs in sandstone reservoirs,such as low utilization degree,high water⁃bearing and low oil recovery rate,a set of well pattern, multiple sets of layers,polymer flooding,and the method of reverse⁃exploiting second⁃class reservoirs layer by layer was proposed.The parameters such as pore volume,injection rate, polymer injection volume and slug combination were optimized by numerical simulation in Pu I1-2 layers of Daqing Xing Twelve area.The results showed that when the PV number was 1 PV,the injection rate was 0.16 PV/a,the polymer injection volume was 1 200 mg/L⋅PV,the high⁃concentration polymer slug was injected first, then the low⁃concentration polymer slug was injected,and the recovery rate reached 50.11%.Compared with the predicted water flooding recovery rate,it was improved by 10.1%.
The cost of the scheme can be reduced by selecting the appropriate test method and result of wax appearance point (WAT).The WAT of high pour point oil in SY and KF oilfields under different conditions was measured by four test methods.The results showed that the WAT measured by microscopic observation,differential scanning calorimetry,laser and rheological methods decreased in turn. It can be divided into the crystallization temperature,critical wax deposition temperature and deposition influence temperature according to the test conditions.The WAT was independent of wax content,and was greatly influenced by high carbon paraffin.The WAT of live oil near saturation pressure was the smallest,which decreased by 9 ℃ compared with the degrassed crude oil.When the pressure of degrass crude oil increases from 0.1 MPa to 24 MPa,the wax evolution temperature increases by 3.1 ℃.The WAT decreased by 2.9 ℃ when the shear rate of live oil increased from 10 s-1 to 1 191 s-1 under the same pressure.Influenced by the asphaltene deposition, the deposition temperature is higher than the critical wax deposition temperature when the pressure was lower than 15 MPa.The rheological test results meet the engineering needs, and the activation energy method can be utilized to deal with the experimental results.This study can provide theoretical and technical support for the selection of WAT in engineering.
Reversible invert emulsion can combines the advantages of different liquid forms in one to play a better role that is expected, it is mainly used to prerare reversible invert emulsion drilling fluid. Thought about the hydrochloric acid used in the oilfield is mainly industrial hydrochloric acid(concentration is 15%~20%),which is different from the diluted hydrochloric acid(concentration is near 5%) used in laboratory, and the concentration of different batches industrial hydrochloric acid is also different, this paper take a study on the effect of the concentration of acid and alkali on the performance of the pH⁃responsive reversible invert emulsion.Studies have been conducted on the effects of acid and base concentration on the pH⁃controlled reversible emulsion,by measuring microstructure and bulk properties of the emulsion.The studies demonstrated that, different acid/base concentrations result in different acid/base densities can affecting the phase transition point of the reversible emulsion, the difference in acid/base concentration causes the volume of the aqueous phase accompanying the addition of acid/base to the emulsion system, which also affects the phase transition point of the reversible emulsion, but the former has a greater impact than the latter.
An associative seawater⁃based fracturing fluids with temperature resistance of 180 ℃ was formed by thermostable and salt⁃resistant thickening agent containing hydrophobic groups, physical crosslinking agent with ionic surfactant, high temperature stabilizer and high efficiency chelating agent. The fracturing fluid forms a high⁃strength network structure through the physical association between the hydrophobic groups on the molecular chain of thickener and cross⁃linker, which enhances its viscoelasticity and takes elasticity as the dominant factor. The viscosity of the fracturing fluid can be maintained above 30 mPa•s for 90 minutes at 180 ℃ and 170 s-1, which has good static sand⁃carrying and wall⁃building properties. The viscosity of gel breaking fluid is 3.3 mPa•s, the residual content is 45 mg/L, and the damage rate of core permeability is less than 10%. The seawater⁃based fracturing fluid meets the requirements of fracturing for offshore ultra⁃high temperature deep reservoirs.
The offshore natural gas condensate wellhead platform has the characteristics of limited space, far from land, no permanent staff and high maintenance cost, which poses a higher challenge to the desanding equipment and technology. In order to solve this problem, a compact tubular sand removal equipment with small volume is proposed.The performance of the sand removal device is evaluated with pressure drop, mass separation efficiency and particle separation efficiency as evaluation indicators. The results show that the mass separation efficiency increases rapidly in the process of the separation chamber diameter changing from D1 to 2D1. Continuing to expand the diameter of separation chamber, the increasing trend of mass separation efficiency decreases and the pressure drop of sand remover increases rapidly; The desander with two⁃stage separation structure has obvious improvement in separation performance, and the mass separation efficiency has been increased by more than 20%. Comparing the particle size of separated gravel with the critical particle size of pipeline carrying sand and the critical particle size of wellhead safe operation, it can be concluded that the separation efficiency of large grain gravel can reach more than 80%, and the tubular desander can complete the pre⁃separation task of offshore wellhead platform gravel.
In order to improve the fluidity of wax⁃containing crude oil and ensure the normal operation of the oil pipeline, this study took paraffin as the only carbon source and selected a strain of hydrocarbon⁃cracking bacteria from the soil polluted by petroleum. After the growth conditions of the bacteria were optimized, the performance of the metabolites of the hydrolytic bacteria was studied, and the effect of the bacteria on the wax removal and viscosity reduction of Daqing crude oil was investigated. From different experimental perspectives, it was proved that the bacteria could emulsify the wax⁃containing crude oil of Daqing, reduce the surface tension of oil and water, and also have a good effect on the wax removal and viscosity reduction. The results show that the wax content of crude oil is reduced by 54%, the wax evolution point is reduced 2 ℃, the related abnormal pointis reduced by 3 ℃, the viscos
Using insulated tubing as production string is an effective measure to raise wellhead oil temperature and to reduce energy consumption of gathering and transportation system. Through investigation and analysis, optimization of aerogel as heat insulation material for insulated tubing, the thermal insulation effect of the insulated tubing is further verified by the measured data. Taking the actual oil well as an example, the governing equations of flow and heat transfer for down hole insulated tubing are established, the heat transfer characteristics of the insulated tubing are numerically simulated, and the influence of different insulation structures on the temperature drop of the oil flow in the pipe is studied. The results show that the four insulation structures meet the production requirements by using 6 mm,10 mm,6 mm+10 mm and 3 mm+10 mm, which provides a theoretical basis for the production of thermal insulation tubing by aerogel nano insulation materials.
In the pipeline operation, the phenomenon of wax deposition often occurs, which will lead to the reduction of the volume of transmission and even the occurrence of condensation accident. For Songshan⁃Huludao thermal insulation crude oil pipeline conveying Qingji mixed oil, a self⁃made indoor thermal insulation ring experimental device wasdeveloped, and a stepwise regression model and a support vector machine model of wax deposition rate were established. The results of comparison and verification showed that the stability and accuracy of the support vector machine model were higher than that of the stepwise regression model. The wax deposition rate model was used to predict the wax deposition in different seasons, which provided a theoretical basis for the determination of the optimal paraffin removal period.
Although the traditional profile control methods can displace and plug high reservoir and effectively use medium permeability reservoir. It is impossible to make effective use of low permeability reservoirs. The high formation pressure affects the injection volume and development effect of profile control and flooding agent. Taking medium⁃low permeability reservoirs as the research object, experimental study on weak gel and water alternating injection was carried out to reveal the mechanism and effect of cyclic deep profile control. The experimental results showed that the effect of cyclic deep profile control method was better than that of traditional profile control method. Compared with core No.1 (whole injection), the recovery of core No.2 (two rounds) was increased by 3.6%, and that of core No.3 (three rounds) by 5.3%. With the increase of injection cycles, the recovery rate increases, and the cyclic deep profile control method could improve the recovery rate of low permeability reservoir on the basis of effectively utilizing medium and high permeability layers. The field test results showed that after 2 rounds of gel deep flooding test, the cumulative oil volume in the experimental area was 1.53×104 t, and the recovery stage was 1.66%. The results have important practical significance for improving oil recovery in medium⁃low permeability reservoirs.
To solve the problem of low oil production ability of some wells caused by the imbalance of pressure in the water,polymer and ASP flooding of different regions of the same development zone in high water cut block X of Daqing oilfield in the high water cut,statistical calculation, theoretical analysis combined with reservoir numerical modeling are applied. It is concluded that the mutual interference of pressure in the high and low pressure areas of the reservoir plane is mainly caused by the difference in the pressurization effect of different oil displacement reservoirs,and the well number of the high and low pressure areas that need to be adjusted is determined.After that,through increasing the injection rate of water wells in the low⁃pressure area of the reservoir,fracturing the water wells of high⁃pressure and low⁃permeability reservoir block, and rising the production rate of the oil wells of high⁃pressure, medium⁃high⁃permeability regions, the imbalance of reservoir plane pressure is adjusted,and the mutual interference between high⁃pressure and low⁃pressure wells is alleviated.After adjusting the block pressure, the daily increase rate of oil wells in the same drive layer is above 2.5 t,and a good development adjustment effect is obtained.
