The electrochemical corrosion behaviour of three Zr-Ag alloys (Zr-1Ag, Zr-3Ag and Zr-5Ag) was investigated. Open circuit potential, linear potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) ...The electrochemical corrosion behaviour of three Zr-Ag alloys (Zr-1Ag, Zr-3Ag and Zr-5Ag) was investigated. Open circuit potential, linear potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were employed in aerated artificial saliva (pH = 4.0) at 37°C. Silver alloying additions are found to be effective in enhancing the corrosion resistance of zirconium in artificial saliva environment. In fact, Zr-Ag alloys exhibit higher open circuit potentials, larger breakdown potentials and higher impedance values as compared to cp Zr. This behaviour can be ascribed to the formation of a thicker and more stable passive film with increasing compactness, able to provide better protection against the corrosion attack.展开更多
The influence of water pollution and welding defects on MIC (microbiologically influenced corrosion) was studied. The open circuit potential (OCP) was measured during MIC test. It was found that OCP shifted to a highe...The influence of water pollution and welding defects on MIC (microbiologically influenced corrosion) was studied. The open circuit potential (OCP) was measured during MIC test. It was found that OCP shifted to a higher level when the system was inoculated with bacteria while the OCP of those samples in water without bacteria was kept at a low level. The OCP decreased dramatically when MIC started in polluted water. Combination of weld defect heat tint, polluted water and adding bacteria causes MIC happen at high rate. Some elements inside the tubercle were analyzed with EDXA. The pits and biofilm were observed with SEM. Microbiological analysis revealed the difference of bacteria between corroded and uncorroded samples.展开更多
Calculating the absolute open flow potential timely and investigating production capacity so as to adjust working system of production wells is one of main means to effectively recovery gas reservoirs during intermedi...Calculating the absolute open flow potential timely and investigating production capacity so as to adjust working system of production wells is one of main means to effectively recovery gas reservoirs during intermediate and late development stage.In order to obtain the open flow potential of gas wells accurately,a new method which utilized a single steady point was proposed in this research,which was based on deliverability formula of a gas well in pseudo-steady state flow with pseudo-pressure form.The influence on factor B in binomial productivity equation caused by the changed permeability was taken into consideration.According to the stable production data,reservoir permeability K can be determined by iterative method firstly,and the coefficient A,B in binomial productivity equation can be calculated with the open flow potential subsequently.It illustrated clearly by a practical example that the new method was suitable for gas wells especially when the producing pressure drop is large.Additionally,the error between the open flow potential value and interpretation result from the multi-point test was small,which proved it to be more simple,economic and effective than the common one.展开更多
文摘The electrochemical corrosion behaviour of three Zr-Ag alloys (Zr-1Ag, Zr-3Ag and Zr-5Ag) was investigated. Open circuit potential, linear potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were employed in aerated artificial saliva (pH = 4.0) at 37°C. Silver alloying additions are found to be effective in enhancing the corrosion resistance of zirconium in artificial saliva environment. In fact, Zr-Ag alloys exhibit higher open circuit potentials, larger breakdown potentials and higher impedance values as compared to cp Zr. This behaviour can be ascribed to the formation of a thicker and more stable passive film with increasing compactness, able to provide better protection against the corrosion attack.
文摘The influence of water pollution and welding defects on MIC (microbiologically influenced corrosion) was studied. The open circuit potential (OCP) was measured during MIC test. It was found that OCP shifted to a higher level when the system was inoculated with bacteria while the OCP of those samples in water without bacteria was kept at a low level. The OCP decreased dramatically when MIC started in polluted water. Combination of weld defect heat tint, polluted water and adding bacteria causes MIC happen at high rate. Some elements inside the tubercle were analyzed with EDXA. The pits and biofilm were observed with SEM. Microbiological analysis revealed the difference of bacteria between corroded and uncorroded samples.
基金Fund project:National Basic Research Program of China(973 Program-2014CB239205).
文摘Calculating the absolute open flow potential timely and investigating production capacity so as to adjust working system of production wells is one of main means to effectively recovery gas reservoirs during intermediate and late development stage.In order to obtain the open flow potential of gas wells accurately,a new method which utilized a single steady point was proposed in this research,which was based on deliverability formula of a gas well in pseudo-steady state flow with pseudo-pressure form.The influence on factor B in binomial productivity equation caused by the changed permeability was taken into consideration.According to the stable production data,reservoir permeability K can be determined by iterative method firstly,and the coefficient A,B in binomial productivity equation can be calculated with the open flow potential subsequently.It illustrated clearly by a practical example that the new method was suitable for gas wells especially when the producing pressure drop is large.Additionally,the error between the open flow potential value and interpretation result from the multi-point test was small,which proved it to be more simple,economic and effective than the common one.
