氯离子对石油测井仪器用Cr13不锈钢点损伤行为的影响

采用高温高压模拟环境装置和实时动电位极化和交流阻抗技术对石油测井仪器用Cr13不锈钢在模拟井下不同氯离子环境中电极的腐蚀失重和电化学行为进行了研究.实验结果表明,当地层水或者钻井液中氯离子浓度较高时,Cr13不锈钢表面的点损伤难以避免;随着氯离子浓度的升高,Cr13的均匀腐蚀速率增大,试样表面点蚀坑增多;局部氯离子以FeCl2和FeCl3形式吸附是造成钝化膜损伤的主要原因.应尽量减少仪器在含氯离子环境中的停留时间或提高材料等级.

Effect of chlorine ion on the pitting corrosion behavior of Cr13 stainless steel for RFT (repeat formation tester)

The corrosion weight loss and the electrochemical behavior of Cr13 stainless steel electrode are studied in the simulated downhole environments of different chlorine ion concentrations in a high-temperature and high-pressure unit. The experimental results shown that, the pitting damage on the surface of Cr13 stainless steel can not be avoided when the concentration of chlorine ion is higher in formation water or drilling fluid; the uniform corrosion speed of Cr13 stainless steel and the corrosion pits on the surface of test samples increase with the increase of the concentration of chlorine ion; the adsorption of local chlorine ion in the form of FeCl_2 and FeCl_3 on the surface of test samples is the main cause resulting in passivating film damage. Therefore, the detention time of RFT in the environment with chlorine ion should be reduced or the grade of the stainless steel for RFT should be enhanced to decrease its corrosion.