Abstract:

In the course of extracting gas from a field, several corrosive gases(H₂S, CO₂) will be produced, and at the same time, entrained condensate with high mineralization and high chlorine ion concentration will increase the danger of corrosion and leaking of gas field equipment and pipelines. Corrosion inhibitor addition is a typical anti-corrosion measure in oil and gas fields to lower the danger of corrosion and leakage in unit. Corrosion characteristics analysis is done based on the process flow and corrosion status of the gas field sewage treatment system, the types of corrosion in this environment mainly include acidic water corrosion, carbon dioxide corrosion, wet hydrogen sulfide damage, underdeposit corrosion, and microbial corrosion. Performance evaluation tests are conducted on two types of corrosion inhibitors by simulating on-site sewage corrosion environment, the selected organic amine+quaternary ammonium salt complex corrosion inhibitor has relatively good protective effect in the environment. The on-site verification test results indicate that when the dose is 150 mg/L, the corrosion inhibition rate reaches 85.5%, the corrosion rate of sewage tank in treatment station is controlled below 0.1 mm per year, the leakage rate of the pipeline in the unit area decreases by 62.5%, and the corrosion inhibitor has a good protective effect.

Key words: sewage treatment system, corrosion characterization, alcohol containing sewage, sulfur containing sewage, corrosion inhibitor, iron ion concentration, resistance probe detection, wall thickness monitoring

摘要：

在气田开采过程中会产生大量的腐蚀性气体(H₂S、CO₂),同时夹带出高矿化度和高氯离子含量的采出液，会加剧气田地上设备及管道的腐蚀泄漏风险。通过加注缓蚀剂来降低装置的腐蚀泄漏风险是油气田常用的防腐措施。基于气田污水处理系统的工艺流程和腐蚀现状进行腐蚀特征分析。该环境中的腐蚀类型主要包括酸性水腐蚀、CO₂腐蚀、湿硫化氢破坏、垢下腐蚀和微生物腐蚀。通过模拟现场污水腐蚀环境开展了两种缓蚀剂的性能测评试验，筛选出的有机胺+季铵盐复配物缓蚀剂在该环境下的防护效果相对较好。现场验证试验结果表明，当缓蚀剂加注量为150 mg/L时，缓蚀率达到85.5%,处理站排污罐的腐蚀速率控制在0.1 mm/a以下，装置区管线的泄漏率减少62.5%,防护效果良好。

关键词: 污水处理系统, 腐蚀特征, 含醇污水, 含硫污水, 缓蚀剂, 铁离子浓度, 电阻探针检测, 壁厚监测