P110SS钢腐蚀产物膜结构与性能的研究

发布时间：2018-04-03 22:26

本文选题：P110SS钢　切入点：H_2S/CO_2腐蚀　出处：《西南石油大学》2017年硕士论文

【摘要】：P110SS钢为抗硫套管钢,主要应用于高酸性含硫油气田。在H2S/CO2环境中,钢材与环境介质发生的电化学腐蚀和氢渗透引起的氢脆严重威胁套管钢的正常服役。然而,在腐蚀环境中钢材表面会形成腐蚀产物膜,其性能对腐蚀速率、腐蚀类型和氢渗透行为有决定性的作用。因此,本文对P110SS钢在H2S/CO2环境中腐蚀产物的结构和保护性能进行了研究。采用高温高压釜制备了不同的腐蚀产物,其中H2S/CO2的分压比为1:0、1:3、1:7、0:1,腐蚀时间为5h、18h、72h。测试表明,在分压比为1:0、1:3、1:7的腐蚀环境中形成的均是FeS_(1-x)腐蚀产物,其中包含马基诺矿和立方相FeS;在分压比为0:1的环境中形成的是FeCO_3腐蚀产物。对于各FeS_(1-x)腐蚀产物,经过5 h的腐蚀后,其结构最致密,保护性最好;当腐蚀时间达到18 h,FeS_(1-x)腐蚀产物膜会经历脱落和晶粒二次生长的过程,因此其保护性最低;当腐蚀时间达到72 h后,腐蚀产物膜得到一定的修复,保护性提高,但仍然低于经过5h形成的腐蚀产物膜。但是在抑制氢渗透的能力上,腐蚀72 h形成的FeS_(1-x)腐蚀产物膜高于腐蚀5h形成的FeS_(1-x)腐蚀产物。当腐蚀时间为5h和72h时,随着CO2分压的增加,FeS_(1-x)腐蚀产物中马基诺矿的含量逐渐增大,立方相FeS的含量逐渐减小,腐蚀产物膜的保护性和抑制氢渗透的能力均逐渐增强。FeCO_3腐蚀产物膜的保护性和抑制氢渗透的能力均随腐蚀时间的增加而急剧增大,并且当腐蚀时间均为18 h和72 h时,以上性能均远高于FeS1x腐蚀产物膜。将以上各分压比中腐蚀72h形成的腐蚀产物膜分别在CaCl_2、MgCl_2、Na_2SO_4和NaHCO_3溶液中浸泡后,对其形貌和保护性能进行了分析。实验结果表明,经过CaCl_2和MgCl_2溶液浸泡后,FeS_(1-x)腐蚀产物的溶解程度较大,对基体局部腐蚀的抑制作用较弱,其保护性均随着CO2分压的增加而下降。经过Na_2SO_4和NaHCO_3溶液浸泡后,FeS_(1-x)腐蚀产物的溶解较小,对基体局部腐蚀的抑制作用较强,其保护性均随着CO2分压的增加而增强;但是以上溶液对FeC03腐蚀产物膜的侵蚀作用均非常轻微,并且FeC03腐蚀产物膜的保护性显著强于各种FeS_(1-x)腐蚀产物膜。对于各腐蚀产物膜,在不同溶液中保护性从高到低的顺序均为:NaHCO_3、Na_2SO_4、CaCl_2、MgCl_2。
[Abstract]:P110SS steel is a sulfur-resistant casing steel, which is mainly used in high acid sour oil and gas fields.In H2S/CO2 environment, electrochemical corrosion and hydrogen embrittlement caused by hydrogen permeation and electrochemical corrosion of steel and environmental media seriously threaten the normal service of casing steel.However, the corrosion product film is formed on the steel surface in corrosion environment, and its performance plays a decisive role in corrosion rate, corrosion type and hydrogen permeation behavior.Therefore, the structure and protective properties of corrosion products of P110SS steel in H2S/CO2 environment were studied in this paper.Different corrosion products were prepared in a high temperature and high pressure kettle. The partial pressure ratio of H2S/CO2 was 1: 0: 1: 1: 1: 1: 7: 01, and the corrosion time was 5 h / 18h / 72h.The results show that all the corrosion products formed in the corrosion environment with a partial pressure ratio of 1: 0 / 1: 1: 3: 1: 7 are FeSZ 1-x) corrosion products, which contain the Markino ore and cubic phase FeS, and the FeCO_3 corrosion products are formed in the environment with a partial pressure ratio of 0:1.After 5 h corrosion, the structure of the corrosion product is the densest and the most protective, and when the corrosion time reaches 18 h, the corrosion product film will undergo the process of shedding and grain secondary growth, so its protection is the lowest.When the corrosion time reaches 72 h, the corrosion product film is repaired and the protection is improved, but it is still lower than the corrosion product film formed after 5 hours.However, in the ability of inhibiting hydrogen permeation, the corrosion product film formed by corrosion for 72 hours is higher than that formed after corrosion for 5 hours.When the corrosion time is 5h and 72h, with the increase of CO2 partial pressure, the content of Macino ore in the corrosion product increases gradually, and the content of cubic phase FeS decreases gradually.The protection of corrosion product film and the ability of inhibiting hydrogen permeation increased rapidly with the increase of corrosion time, and when the corrosion time was 18 h and 72 h, the protective and inhibiting hydrogen permeation ability of corrosion product film increased rapidly with the increase of corrosion time.The above properties are much higher than FeS1x corrosion product films.The corrosion product films formed during 72 hours of corrosion in the above partial pressure ratios were soaked in CaCl _ 2MgCl _ 2C _ 2N _ 2SO _ 4 and NaHCO_3 solution respectively. The morphology and protective properties of the films were analyzed.The experimental results show that the dissolution degree of the corrosion products of CaCl_2 and MgCl_2 solution is larger, the inhibition of local corrosion of the matrix is weaker, and the protection of the corrosion products decreases with the increase of the partial pressure of CO2.After soaking in Na_2SO_4 and NaHCO_3 solutions, the dissolution of the corrosion products was relatively small, the inhibition of local corrosion on the substrate was stronger, and the protection of the corrosion products increased with the increase of partial pressure of CO2, but the corrosion effect of the above solutions on the corrosion product films of FeC03 was very slight.Moreover, the FeC03 corrosion product film is much more protective than various FeS-1-x corrosion product films.For each corrosion product film, the order of protection from high to low in different solutions is: NaHCO _ 3 / S _ 2SO _ 4 / CaCl _ 2MgCl _ 2.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG178

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