The galvanic corrosion behavior of magnesium alloy and Q235 steel system different Sc/Sa(negative / anode area ratio) in simulated solution of tank bottom water in Daxie oil depot was studied by immersion experiment, electrochemical test and micro morphology observation method. The impact of different Sc/Sa on corrosion rate was found out, which curve and expression were fitted. The results show that, the corrosion rate of magnesium alloy anode increases greatly with the increasing of Sc/Sa, but the increasing of corrosion rate for the negative part is not obvious. Based on the galvanic current image, the galvanic current fluctuates and decreases with time. When Sc/Sa is 1.0 or 2.0, the galvanic current decreases obviously, which does not decrease obviously when Sc/Sa is 0.5. The corrosion rate is calculated by galvanic current. It is demonstrated that the galvanic current, as well as the corrosion degree increases linearly with the increase of Sc/Sa.

Through the heat transfer analysis of the experimental loop of the insulated crude oil, the calculation model of the experimental loop temperature field of the insulated waxy crude oil was established.The internal temperature distribution of the pipeline and the variation of the temperature gradient of the inner wall of the pipeline were calculated.The effects of different ambient temperature,oil flow velocity and wax formation on the temperature field distribution of the pipeline were studied.The results showed that the greater the temperature difference between the oil temperature in the tube and the cooling water in the casing,the larger the average temperature gradient of the tube wall.The average temperature gradient of the pipe wall increased as the oil flow velocity increased,however,when the temperature gradient of the inner surface of the sediment deposit layer on the pipe wall was lower than the initial time, the magnitude of the decrease gradually decreased as the length from the inlet end increased.

Due to the effects of service environment, corrosion defects inevitably appear on pipeline surface, which will cause stress concentration and promote crack nucleation. In this study, a coupled stress and electrochemical multi⁃physical field model for predicting the morphological development of corrosion defects was established based on the finite element method. The time dependence of stress corrosion behavior and corrosion morphology of X70 pipeline steel in sea mud simulated solution were studied by using the established model via deformation geometry and dynamic mesh technology. The results showed that the mechanical⁃electrochemical effect played an important role in the nucleation of stress corrosion cracks. The smaller the width of corrosion defects, the greater the stress concentration, the negative shift of the electrode potential and the higher the corrosion rate. With the increase of the operating pressure, there was a large area of high stress concentration area in the bottom of the corrosion defect, and the area of metal loss caused by corrosion increased.

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.

The leakage geometry region of natural gas pipeline was provided. The leakage control equation of natural gas was established on the control volume principle and porous media theory. The numerical simulation was performed on the leakage of buried natural gas pipeline by using computational fluid dynamics software. Through the process of simulation, the concentration distribution of leakage natural gas in soil and air were got. The wind speed affect the diffusion law of natural gas was analyzed, the safe region was confirmed. The theoretical reference for emergency rescue and safety management of natural gas pipeline leakage was provided.

To the batch transportation of cool and hot crude oil, the total cost of transporting oil consists of fuel cost of fire furnace and power consumption cost of oil pump. It is very important to make the total consumption minimal under the premise of accomplishing safely transporting task. Taking the minimal of total energy consumption as the objective function, a batch transportation model of cool and hot crude oil pipeline was set up. The batch transportation in the model was divided into four time stages that unsteady stage of the cold oil head heated, quasi-steady-state stage of the cold oil unheated, unsteady stage of the cold oil end heated and quasi-steady-state phase of the hot oil heated. Two-layer nesting method was used to solve the quasi-steady-state stage; both two-layer nesting method and meeting the pitted in-station temperature of oil head (oil end) were used to select the optimization scheme. Combined the engineering practice, the optimization example of the batch transportation of cool and hot crude oil was given, and the research results can provide a decision-making basic for optimizing transmission of the batch transportation of cool and hot crude oil.

X80 pipeline steel specimens were treated by electrochemical hydrogen charging under various current densities and charging time. The polarization resistance and corrosion rate of X80 steel were analyzed in Yingtan simulated soil solution under the different hydrogen charging conditions. The results show that with the hydrogen charging current density increased from 1 mA/cm ² to 20 mA/cm ², the free-corrosion potential of X80 moved negatively, charge transfer resistance Rt dropped from 1 176 Ω·cm ² to 909 Ω ·cm ², double electric layer capacitors increased from 0.000 16 μF/cm ² to 0.001 7μF/cm ² and corrosion current density increased from 3.322 mA/cm ² to 6.880 mA/cm ². When filling hydrogen time increased from 1 h to 5 h, Rt changed from 1 522 Ω ·cm ² down to 749 Ω ·cm ², double electric layer capacitors increased from 0.000 14 μF/cm ² to 0.007 5 μF/cm2 and corrosion current density increased from 2.91 mA/cm ² to 5.01 mA/cm ². This suggests that electrochemical hydrogen charging result in anodic dissolution rate of the weak spots and concentration of metal ions increased. Hydrogen speeded up anodic dissolution of X80 steel and leaded to higher corrosion sensitivity at the steel surface.

Cyclic voltammetry was used to comprehensively investigate the fundamentals of the electrochemical corrosion reactions occurring at the steel／solution interface in Yingtan soil simulated solution． The interrelation between anode polarization and the cathodic hydrogen evolution was studied by changing the sweep rate， the upper potential limit，ions concentration and gas conditions．The results show that the electronically behaviors of X80 steel are irreversible charge transfer process．There is no stable oxide film formed on the steel surface． The anode polarization and cathodic hydrogen evolution reaction are enhanced by the corrosive ions in the solution ．The hydrogen evolution was catalyzed by the stable deposition film which generated during the anode polarizing．The introduction of oxygen could form a stable oxide film，which weakened the
catalysis to the hydrogen evolution．The stress corrosion cracking sensitivity of the welded metal is increased by CO_２ introduced to the solution．

According to heat transfer and filtration theory ，mathematical model and its control equation of ground － source
heat pump in cold climate were put forward ．The in heating situation was simulated by using finite element method to ground
－ source heat pump heating of the Daqing oil field in winter ．By comparison with and without consideration of soil freezing ，the
results show that the phase change latent heat could reflect the heat transfer effect ． The soil freezing can increase thermal
conductivity ，which is beneficial to the heating effect and pump efficiency ．

The safety management was among the most important management work for oil and gas pipelines． As an alternative，the risk grading division based on WebGIS was being considered to improve safety management．An information
management system for oil and gas pipeline based on WebGIS had been established using ArcGIS Server as the developing system of WebGIS，SQL Server as the database to store pipeline data and ArcSDE as the GIS Server．According to the practical pipeline situations，the expert grading method on risk assessment of oil and gas pipeline set by Muhlbauer W K was modified．
An analytic hierarchy process （AHP） was introduced to comprehensively evaluate the expert grading method，and a kind of categorization method for the risk of oil and gas pipelines was proposed．Finally，it was demonstrated with examples that this improved categorization method based on WebGIS is more intuitive and easier to apply．

The microstructure of X80 pipeline steel systemically was characterized by optical microscope, scanning electronic microscope, and transmission electron microscope, and studied electrochemical behavior of X80 pipeline steel in Ku'erle simulated soil solution, NS4 solution and Yingtan simulated soil solution by Potentiostat/Galvanostat model 2273.  It is shown that the microstructure of X80 pipeline steel is characterized by polygonal ferrite, acicular ferrite, and martensite-austenite (M/A) constituents.  There are dislocation cells and sub-grains in a ferrite grain and a lot of dislocation tangled around ferrite grain boundaries.  Only active region, and no

active-passive transition region is found in polarization curves of X80 pipeline steel in Ku'erle simulated soil solution, NS4 solution and Yingtan simulated soil solution.  Corrosive current density of X80 pipeline steel is the largest in Ku'erle simulated soil solution, and less in NS4 solutions, and the least in Yingtan simulated soil solution. Corrosive current density of X80 pipeline steel in Yingtan simulated soil solution is close to that of in NS4 solutions, but both of them much less than that of in Ku'erle simulated soil solution.

For the exposed crude oil pipelines，the heat capacity of oil in pipelines was much smaller than that in surrounding soil，so the cooling rate of exposed line was much faster than that of the buried line．And it becomes the key to limit shutdown time of oil transport line．Based on the bare hot oil pipeline thermal and hydraulic characteristics， established a pipeline shutdown temperature drop mathematical model．Use finite difference method after simplifying the model，changed the heat transfer partial differential equations into a system of linear equations，then used iterative method to calculate．Compile program diagram of the shutdown temperature drop of temperature field，calculated temperature distribution during different shutdown time．Compared the temperature of the governing center， 1/2 radius of the wall， developed a viable intermittent oil
transportation program．

 

For gas pipeline, simulating the working condition was necessary in order to work safely and economically and manage rationally. Some gas pressure was up to 10 MPa in the pipeline, in which the result by equation for ideal gas has the greater error. L-E-E equation was applied to solve the physical parameters such as the compression factor, practice gas density, specific heat, adiabatic index, entropy, enthalpy and so on. And the program was compiled to calculate the properties. The calculate results show that L-E-E equation is much accurate and can be applied widely in the practice.

The integer which was coded partheno-genetic algorithm (IPGA) will be used in the optimization of products pipeline pump distribution program. The rotation speed of pump was regarded as the decision-making variable. The optimization results were formed into chromosomes by using integer coding solution. Corresponding genetic methods and adaptation function were designed, and data of the western pipeline was used for verifying and calculating. The result shows that IPGA is feasible on product pipeline optimization.