H2S与CO2共存条件下气田地面集输系统内腐蚀影响因素分析方法研究

Study on analysis method of internal corrosion affecting factor under the coexistence of CO2 and H2S in surface gathering system

关键词:  内腐蚀  影响因素  主导因素  归一化处理

Key words:  internal corrosion  affecting factor  main factor  normalization treatment

摘要:

CO₂和H₂S是最常见的两种管道内腐蚀介质,当系统中H₂S和CO₂共存时,其腐蚀行为远比H₂S或CO₂单独作用时复杂得多,即便是少量的H₂S也会对CO₂的腐蚀产生明显的影响,对气田开采与管输设备造成严重的破坏,甚至引发设备失效与安全事故。CO₂/H₂S共存体系下的金属腐蚀规律十分复杂且难于把握,与两种因素单一存在时截然不同。国外早期的研究始于20世纪80年代末,国内起步相对较晚。经过近30年的研究,发现腐蚀过程受CO₂或H₂S的控制取决于两者的含量、介质温度、压力、流速等因素。根据川东气田的气质和工况环境,进行实验研究与深入的理论归纳分析,得出川东气田H₂S与CO₂共存条件下地面集输系统内腐蚀影响因素及其交互作用的腐蚀影响权重。在此基础上,利用归一化方法,计算出重庆气矿中高含硫气井的腐蚀风险权重值,筛选出腐蚀敏感度较高的需要重点关注的气井及其采气管线。 

Abstract:

CO₂ and H₂S are two popular internal corrosion medias in pipeline, when CO₂ and H₂S coexistence, the corrosion behavior is much more complicated than CO₂ or H₂S existing independently. Even if a small amount of H₂S will have significant impact on CO₂ corrosion, which can damage the ground equipment seriously,and even cause equipment malfunction and safety accidents. The corrosion rule is very complex and difficult to control when CO₂ and H₂S are coexistence, because it is completely different from the single existence of the two factors. The abroad studies of this corrosion began in the late 1980s, and domestic studies started relatively late. After 30 years study, we find that the corrosion progress depends on the content of CO₂ and H₂S, medium temperature, pressure, flow rate and other factors. According to the gas properties and operating conditions of East Sichuan gas field, this paper carried on experimental research and theoretical induction analysis, then obtained the internal corrosion affecting factors and corrosion effect weights of their interaction under the coexistence of CO₂ and H₂S in the surface gathering system. On this basis, using normalization method, the corrosion risk weights of high sulfur gas wells in Chongqing Gas Distric were calculated, and the gas wells and pipelines with high corrosion sensitivity were selected, which need special attention.