水溶性缓蚀剂在中低二氧化碳气井的应用

中国石油天然气股份有限公司长庆油田分公司上古气井具有中低二氧化碳、高矿化度及介质pH值变化大的腐蚀特点,同时气井井筒温度多处于腐蚀行为和机理多变的敏感区(60～100℃),这些特点对缓蚀剂的适应性提出了较高的要求。该文主要针对上述腐蚀环境的行为特征,通过缓蚀剂物化性能、相关配伍性、电化学性能、高温高压及现场井筒挂片质量损失分析,研究开发出适合中低CO2、高矿化度水气井腐蚀环境的水溶性缓蚀剂(HGCQ),具有水溶性良好,高温及低温稳定性优良,与甲醇及甲基二乙醇胺(MDEA)配伍性好的特点。室内研究了该缓蚀剂的缓蚀机理为阳极抑制型,确定其现场最佳加注质量浓度为300 mg/L。进行了模拟占古气井筒腐蚀环境的高温高压腐蚀试验和现场一口气井3个月的质量损失挂片测试,结果表明该缓蚀剂缓蚀效果明显,可以有效控制气井管柱的腐蚀。

Application of Water Soluble Corrosion Inhibitor in Gas Well with Low CO2

The Shanggu Gas Well of PetroChina Changqing Oil Field Company is characterized by low CO2, high minerality and greater variations of pH value of media, and gas wellg tube temperatures are mostly in the sensitive range （ 60 - 100℃） where the corrosion behavior and corrosion mechanisms change frequently. All these features impose a high requirement for the compatibility of corrosion inhibitor. Based upon the analysis of the characteristics of the above corrosion environment, the corrosion inhibitorg physical and chemical properties, associated compatibilities and electro - chemical performance as well as mass - loss of coupon testing in high temperature, high pressure and well tube, a water - soluble corrosion inhibitor （HGCQ） has been successfully developed for the corrosion environment of gas wells with low CO2 and high minerality. The corrosion inhibitor is good in water solubility, excellent in high - temperature and low - temperature stabilities and good in compatibility with methanol and MDEA. The laboratory tests have confirmed that the corrosion inhibition mechanism of the corrosion inhibitor is anode inhibition type and the optimal addition dosage is 300 mg/L. The high - temperature and high - pressure testing of simulated corrosion environment of Jingbian gas well and 3 months＂ mass - loss field coupon testing in a gas well show that the corrosion inhibitor is good in corrosion inhibition performance and effective in controlling the corrosion of pipe of gas well.