Microbes can improve the fluidity of waxy crude oil and increase the efficiency of transportation. The cultured Bacillus subtilis 6# and Pseudomonas aeruginosa 3# were mixed and cultured in a ratio of 2∶3, the growth conditions were optimized. DSC, polarizing microscope, HAKEE rheometer and interfacial tensiometer were used to analyze the effect of compound bacteria and waxy crude oil. The results showed that: after treatment with compound bacteria, the wax precipitation point of waxy crude oil decreased by 2.23 ℃, the peak point of wax precipitation decreased by 2.71 ℃, and the wax content of crude oil decreased by 51.64%; the wax crystal structure changed significantly; the apparent viscosity of crude oil decreased by 64.72% at 37 ℃. In addition, the emulsification index of the compound bacteria on liquid paraffin was 55.39%, and the surface tension of the liquid paraffin culture medium was reduced from 79.89 mN/m to 38.83 mN/m. Compared with single bacteria, compound bacteria are more effective in removing wax and reducing viscosity, and have wider application prospects.

Microbial paraffin removal and prevention has the advantages of low cost, safe operation and no damage to the formation. The effects of complex environment on microbial degradation were introduced, the effects of microbial degradation enzymes were analyzed,the effects of organic solvents and biological surfactants produced by microorganisms on the degradation of waxy crude oil were elaborated. Based on this, it is pointed out that the microbial technology should strengthen the research on the production mechanism of microbial degradation enzyme, organic solvent and surfactant, so that the microbial degradation of waxy crude oil has a broader application prospect

In order to explore the influence of deep sea T⁃tube flow difference and pipe diameter abrupt change on the flow characteristic parameters of the vertical pipe, a certain oil and gas field in the South China Sea was taken as the research object, and the numerical simulation method was used. The results show that the influence of flow rate difference is related to the sum of the total flow rate instead of the each flow; the effect of changing diameters of riser pipe on relevant parameters can be divided into three stages: DC=0.03 m, DC=0.06~0.12 m and DC=0.24 m. And when the vertical riser has a sudden change, the flow parameters are mainly related to its minimal pipe diameter.

In order to explore the flow characteristics of vertical pipe in the deep⁃sea horizontal pipe⁃catenary system, in this paper, aiming at an oil and gas field in the south China sea, the influence of diameters, total flow rate, water cut and outlet pressure were simulated. The results show that the position of the flow state in the pipe is the boundary, and the influence of each influencing factor on the flow state parameters in the pipe shows different changes, but the temperature distribution along the pipe is not affected by the relevant factors; From the perspective of the research scope of the above four parameters, the influence process of each parameter is divided into different stages. The influence of pipe diameter is divided into two stages: D=0.06~0.12 m and D=0.12~0.50 m, the total flow of Q=0.001~0.030 m3/s and Q=0.100~0.300 m3/s, the water content of w=10%~25% and w=25%~30%, and the outlet pressure is divided into three stages, including 0~5.0, 5.0~7.0, 7.0~10.0 MPa.

Spherical Fe3O4@SiO2 nanoparticles with good dispersibility (denoted as S1) were prepared by Stöber hydrolysis⁃polycondensation method, and the particle size was 300～430 nm.In order to investigate effect of carbon number in the organosilicone on 51 hydrophobicity and demusification of magnetic nanoparticles, the methyl triethoxysilane, n⁃hexyltriethoxysilane, n⁃dodecyltrimethoxysilane and n⁃octadecyltriethoxysilane were used to modify the surface of the S1 respectively, and the products were marked for S2—S5. The magnetic samples were characterized by electron microscopy (TEM), scanning electron microscope (SEM), X⁃ray diffraction (XRD), fourier transform infrared (FTIR) spectra and thermogravimetric analyses (TGA). The static water contact angle of magnetic nanoparticles (θW) were 10.6º、42.6º、113.6º、128.0º and 148.3º for S1—S5 respectively, and the results indicated that the θW increased with carbon number in the silane coupling agent increasing. Besides, the hydrophobic coating amount on the S1 surface of S2—S5 were estimated to be 0.005, 0.087, 0.092 g/g and 0.087 g/g respectively. The samples can be applied to removal the oil from water surfaces. Four kinds of silicone⁃modified magnetic particles can remove the surface oil, the n⁃dodecyltrimethoxysilane modified magnetic particles have the best effect of removing oil.

The small groove surface flowing in the direction can effectively reduce the wall friction and reduce the energy consumption of transportation. For the gas pipeline with triangular ribs on the inner surface, the large eddy simulation is used to simulate different flow states, and the flow field velocity vector diagram, root mean square velocity profile line and Reynolds shear stress are analyzed. The simulation results show that the best drag reduction effect is achieved when the dimensionless dimension s+=20.7; the vortex formed by the turbulence is cut by the rib peak when passing through the rib to form a small reverse small vortex in the rib, and the fluid is the sliding friction between the wall surfaces which is converted into rolling friction, which reduces the frictional resistance; the velocity profiles of smooth tube wall, rib peak and valley bottom surface only differ greatly near the wall surface, and tend to be consistent far from the wall surface, and the rib pair the influence of the flow field mainly occurs in the near wall area.

In order to study the erosion and wear of sand⁃bearing crude oil pipeline on elbow, the Euler⁃DPM bidirectional coupling model was established by using CFD analysis software.By changing the inlet flow rate, particle mass flow rate, particle diameter and other conditions, the flow field distribution and simulation were carried out with 45° elbow as the research object. The results show that the maximum wear rate increases exponentially with the increase of inlet jet velocity, and the velocity coefficient is 2;under the conditions of constant inlet flow rate and particle size, the maximum erosion wear rate increases linearly with the increase of discrete phase mass flow rate, and the slope is 1.633; the other variables are constant, the particle size is between 50～350 μm, and the maximum wear rate increases with the particle size. The maximum wear rate kept below 3×10－9 kg/(m2·s).When the particle diameter was larger than 350 μm, the maximum wear rate increased rapidly, and the maximum value was 12×10－9 kg/(m2·s).

The most important form of energy loss in long distance gas pipelines is turbulence resistance. In order to study the rib shape on the turbulent situation through the rib of the influence law of fluid medium, this paper uses the CFD software of triangular rib and the blade shape rib between two kinds of typical ribs large eddy simulation under Reynolds number of 5 300, the wall resistance and flow field are analyzed to obtain the shape of the rib with better drag reduction effect, and to find out the reasons why the different shape ribs affect the flow field. The results show that the blade shape ribs have smaller wall resistance and smaller velocity gradient near the wall than the spaced triangular ribs. The secondary vortices generated make the flow field more stable and have better drag reduction effect.

In order to reduce the hazards caused by the severe slug flow in the mixed pipeline, it is necessary to analyze and study its flow characteristics. Taking the experimental system of a horizontal downdip tube⁃catenary riser in some literature as the research object, the relevant mathematical and physical models are established. The CFD software is used to simulate the serious slug flow in this type of pipe, and the characteristics of the severe slug flow and the variation of pressure, velocity and gas content are analyzed.The flow pattern map is obtained by numerical simulation with different inclination angles, pressure curve and cycle variation analysis show that with the increase of the slope angle of the pipeline, the flow pattern map conversion boundary changes, the formation of severe slug flow to the superficial gas velocity increases, forming the intermittent flow to the superficial gas velocity decreases the maximum value; the maximum value of the severe slug flow pressure changes little with the tilt angle, and its period decreases with the increase of the tilt angle, and changes exponentially.

The characteristics of gas⁃liquid two⁃phase flow during the pigging process is helpful to the design and operation of the pipeline itself and the upstream and downstream equipment. In this paper, the multiphase flow simulation software OLGA is used to study the gas⁃liquid two⁃phase flow law during the process of natural gas pipeline pigging. The changes of key analysis pipeline such as flow pattern, pressure, liquid holdup, pigging velocity, fluid volume and other parameters. The results show that: the pigging process in the undulating terrain, the gas⁃liquid two⁃phase stratified flow, slug flow and annular flow pattern. The pressure at the entrance of the pipeline is the largest, and the pressure decreases gradually along with the pressure fluctuation; the overall speed of the pig is not fluctuating, the average speed is about 3.5~3.8 m/s. The maximum length of liquid slug in the process of pigging is 3 851.0 m. The liquid holdup is constantly changing, the maximum clear liquid is close to 300 m3. The research conclusion has certain practical significance to the pigging operation of the natural gas pipeline in the relief area.

Water in oil emulsion was prepared under different water volume fraction,stirring speed and temperature.By simulating the different situations encountered in the process of mixed transportation,the particle size distribution of the emulsion droplets and its relationship with viscosity were analyzed.The results show that when the volume fraction of water is less than 60% in the emulsion,the average particle size of the dispersed phase of the emulsion becomes smaller as the stirring speed is increased,and the viscosity becomes larger.With the increase of temperature,the average particle size of the dispersed phase of the emulsion is larger and the viscosity gradually decreases.As the volume fraction of water increases,the average particle size of the dispersed phase droplets becomes larger,and the viscosity shows a clear upward trend.However,when the water volume fraction is greater than 60%,the viscosity of the emulsion decreases drastically as the volume fraction of water increases,and the flow pattern of emulsion changes.The research results have certain guiding significance for the safe operation of pipelines and the study of gathering and transportation technology.

Wax in waxy crude oil is one of the main reasons for the poor fluidity of crude oil. In order to solve the great difficulties brought by the fluidity of waxy crude oil to crude oil mining and gathering, it is necessary to carry out wax removal treatment on crude oil.Microbial paraffin removal technology is the use of microbial metabolism to directly degrade wax components in crude oil and degrade long chain hydrocarbons into medium and short chains, thus reducing the wax content in crude oil at all. By detecting the wax content in crude oil and wax crystal morphology before and after the treatment of compound bacteria, the effects of the compound bacteria on the degradation of wax components in crude oil and the morphology and size of wax crystals in crude oil are studied, it is concluded that the wax removal characteristics of the compound bacteria are analyzed macroscopically. Finally, the paraffin removal effect of the compound bacteria is verified from the microscopic point by detecting the particle size distribution of the oil sample after paraffin removal treatment.

The most important form of loss of energy in long-distance gas pipelines was turbulence resistance. In order to study the V-shaped riblet influence on the resistance in the gas pipeline, this paper used the software of CFD to simulate two different geometric size of V-shaped riblets and smooth pipe. The Reynolds number was 74 880. By analyzing the flow field in the pipeline, the distribution of vorticity and wall shear stress, the reasons for increasing drag and decreasing resistance were found. Based on this, the drag reduction mechanism was obtained. The results showed that：compared with the smooth gas transmission pipeline，when the riblet size in the pipeline was s ⁺=22, the flow velocity, vorticity value, the area of wall shear stress and the shear stress were small. Riblet had the effect of drag reduction. When the riblet size of the pipeline was s ⁺=44, the flow velocity of the near wall area, the vorticity value at the top of the riblet, the wall shear stress increased area and the shear stress value was large. Riblet had the effect of increasing resistance.

With the rapid development of national economy in our country, the demand of oil and gas, as a representative of the major energy, continued to increase, and the security risks of long distance oil and gas pipelines also caused people's attention. Especially, the pipeline leakage deflagration happened from time to time in recent years, which caused not only great economic losses of the people's lives and property, also caused the ecological environment pollution and destruction. Therefore the leak detection of intelligent and efficient positioning method was applied to oil and it was critical for gas pipelines in a timely manner to prevent secondary disasters. The main cause of pipeline leak was analyzed, several kinds of leak detection methods used on the pipeline at present were summarized, and the method of negative pressure wave and flow balance method was dopt in crude oil pipeline leak detection experiments. The experimental results showed that the method could monitor oil pipeline leak in real time, especially small slow leakage, meanwhile could accurately locate the leak point.

The five common methods used residual strength assessment for oil and gas pipeline were studied.By comparing the results calculated by strength assessment equations and measured by blasting experiments, the calculation error of these equations were obtained.Then the error distribution interval was analyzed.The results showed that the equation of Modified B31G was less conservative than Origin B31G.Allowable stress method and PCORRC equation had the better evaluation results.The evaluation equation given by API 579-1 standard also had the problem of too-conservative evaluation results.For the different grade pipeline steels, the evaluation effects of the same evaluation equation were different.

With the development of marine petroleum industry, marine risers appeared a variety of forms. Due to pipe shapes and the complex seabed terrain factors, severe slugging often happened. This special flow pattern damaged the equipment, production and so on. Therefore, the simulation and the research for the severe slug flow of the marine riser system had very important significance. The research was summarized by the domestic and foreign scholars on the severe slug flow of the multiphase flow riser system, including its research methods, mechanism and characteristic parameters and theoretical model, etc,which provided a reference for further study of severe slug flow in riser system.

The conventional technologies of reducing heavy oil viscosity exit the shortages of affecting the quality of crude oil, heavy workload, high cost and other defects. Therefore, new method of heavy oil viscosity reduction based on hydrocarbondegrading bacteria was discussed. A hydrocarbondegrading bacterium was isolated in the laboratory. Its growth curve and its function of reducing viscosity and wax in heavy oil were studied. The results showed that the reduction rate of crude oil ranged from 22.49% to 32.93% and wax precipitation point decreased from the 44.4 ℃ to 39.5 ℃. The same as wax content dropped from 13.00% to 3.80%. The resin content dropped from 16.45% to 13.75%. After adding D1 strain, wax removal rate was 70.08% and wax precipitation point fell 4.9 ℃. The strain had a significant effect on reducing the viscosity of heavy oil and wax content.

Petrochemical enterprises in Northeast China mainly produced fuel hydrogen from natural gas; the gas units included crude distillation unit, reforming unit, hydro-treating unit, catalyst unit, ethylene unit, delayed coking unit, molecular sieve dewaxing unit, benzene and styrene unit. About （25~30）×10 ⁴ m ³ gas was consumed for one petrochemical enterprise processing ten million tons of crude oil per annum. The main factors that affected the total amount of natural gas consumption included alternative energy, seasonal variation, maintenance, market, emergencies, etc. The calculation of natural gas price bearing capacity with the surrogate worth trade off method showed the price of alternative energy such as naphtha and liquefied gas directly affected the economy of natural gas utilization. Clarifying the use regulation and economic characteristics of nature gas in petrochemical enterprises was conducive to optimizing the plan design of gas utilization, controlling cost and coordinating with the upstream gas suppliers.

The moisture content of soil will change when the ambient temperature changes in permafrost, and by this time the internal friction angle, cohesion and severe of permafrost will change accordingly. And for slope segments of buried pipelines, the soil will produce friction on the pipeline along the slope direction with the thawing of permafrost occurrence, to make the pipeline generate the additional tensile stress. Understanding the impact of frozen soil parameters on the pipeline stress correctly was convenient to the analysis of pipeline stress, and it had practical significance for the development of scientific and effective method of preventing damage. When the frozen soil around the buried pipeline of slope section thaws, the degree of influence on pipeline stress with different soil parameter was investigated, and yields the conclusion by the numerical simulation. The results show: when thaw landslide occurs, with the increasing of soil cohesion and weight of soil, the pipeline stress increased; and with the increasing of internal friction angle, the pipeline stress decreased. Moreover, the friction angle of the frozen soil was the most sensitive to the pipeline stress, weight of soil followed, and the influence of permafrost cohesion on pipeline stress was minimal.

Based on the measured oil station coordinate data and longdistance oil pipeline paper topographic map vector data,using ArcGIS combination of Sketchup modeling to realize 3D visualization,storaging graphics and attribute data in Geodatabase,using C# programming language combine of ArcGIS Engine secondary development component , 3D oil station and longdistance oil pipeline information system were designed. The system realized the functions including 2D and 3D Linkage showes,information inquiry,spatial analysis,information output,system maintenance,etc.