摘要
在模拟高温、高压、高H_2S/CO_2分压的腐蚀环境中,通过高温高压腐蚀模拟实验,结合失重测量、扫描电子显微镜(SEM)和能谱分析(EDS)等技术手段研究了不同Cl^-浓度对镍基合金718腐蚀行为的影响。结果表明:在205℃,CO_2分压3.5 MPa、H_2S分压3.5 MPa的腐蚀环境下,随着Cl^-浓度的增加,腐蚀速率呈现增加趋势,镍基合金718的点蚀敏感性显著增加。当Cl^-浓度达到180 g/L时,镍基合金718表面开始出现点蚀。点蚀起源于表面钝化膜的硫化破坏,Cl^-浓度达到临界值后穿透钝化膜,导致点蚀的产生。虽然在Cl^-浓度达到200 g/L时仍然没有出现应力腐蚀开裂现象,但当Cl^-浓度达到180 g/L时开始出现点蚀,并在应力的作用下点蚀呈现为垂直于应力方向的沟槽状,长时间的服役可能存在应力腐蚀开裂的风险。
Nickel-based alloy 718, as a metallic material for downhole-tools and-facilities, is commonly used in high acid oil and gas wells. In this paper, the effect of chloride ion concentration on the corrosion behavior of nickel-based alloy 718 in a simulated corrosion environment with high H2 S/CO2 partial pressure at high temperature and high pressure was studied by means of weight loss measurement,scanning electron microscopy（SEM） and X-ray energy spectrum analysis（EDS）. The results show that in high acidic environment with 3.5 MPa partial pressure of CO2 and H2 S respectively at 205 ℃, the corrosion rate increases with the increase of chloride ion concentration and the pitting susceptibility is signifi-cantly increased as well. When the chloride ion concentration reaches to 180 g/L, the surface of the nickel-based alloy 718 begins to suffer from pitting corrosion. Pitting corrosion originates from sulfureting induced damages of the surface passivation film, once the chloride ion concentration reaches a critical value and passes through the passivation film, the pitting corrosion may initiate. Although the stress corrosion cracking did not occur at chloride ion concentration of 200 g/L, however, groove-like pitting occurred when it reaches to 180 g/L, which may be the risk of stress corrosion cracking for long-term service.
作者
张瑞
阮臣良
尹慧博
李大朋
廖洪千
路民旭
ZHANG Rui;RUAN Chenliang;YIN Huibo;LI Dapeng;LIAO Hongqian;LU Minxu(State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, SINOPEC Research Institute of Petroleum Engineering, Beij ing 100101, China;Institute of Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China)
出处
《腐蚀科学与防护技术》
CAS
CSCD
北大核心
2018年第3期285-290,共6页
Corrosion Science and Protection Technology
基金
国家科技重大专项(2016ZX0521005)
中国石化科技部攻关项目(P14113)
页岩油气富集机理与有效开发国家重点实验室开放基金(10010099-16-ZC0607-0002)~~
