油气田酸化压裂环境下碳钢油套管材的腐蚀行为研究

Study on Corrosion Behavior of Carbon Steel Oil Casing Materials in Acidizing and Fracturing Environment of Oilfield

为了明确某油田在酸化压裂环境下鲜酸、残酸对油套管材料腐蚀性能的影响规律及材料的适应性,采用腐蚀失重法、三维体视光学显微镜观察等方法分析了P110、C110油管材料在酸化全过程的腐蚀损伤发展趋势、点蚀敏感性和不同条件下的腐蚀形貌特征,并优化了酸化缓蚀剂。结果表明:随着鲜酸酸化温度的逐渐升高,材料腐蚀程度均呈增大趋势,当温度≥180℃时,C110的平均腐蚀速率v_(corr)=127.7 g/(m^(2)·h),P110的平均腐蚀速率v_(corr)=407.0 g/(m^(2)·h),均远高于指标要求;在模拟鲜酸温度为100℃时材料表面已出现点蚀形核现象,随着温度的升高,点蚀敏感性逐渐增大。在超高温180℃的残酸环境下,C110和P110材料均发生极严重腐蚀。酸化液组分中缓蚀剂在高温条件下明显失效,导致残酸返排环境下管材遭受严重腐蚀损伤。优化后的改性曼烯碱酸化缓蚀剂通过多层吸附膜的形成明显减缓了材料的腐蚀速率,在180℃高温鲜酸环境下缓蚀率为89.4%。

For clarifying the influence of fresh acid and residual acid on the corrosion performance of tubing materials and the adaptability of materials in an acid fracturing environment in a certain oil field,the corrosion damage development trend,pitting sensitivity in the whole process of acidizing and corrosion morphology characteristics of P110 and C110 tubing materials under different conditions were analyzed by corrosion weight loss method and three-dimensional stereo optical microscope observation,and the acidizing corrosion inhibitor was optimized.Results showed that as the acidification temperature of fresh acid gradually increased,the degree of material corrosion tends to increased.When the temperature was≥180℃,the average corrosion rate of C110 was_(vcorr)=127.7 g/(m^(2)h),while the average corrosion rate of P110 was_(vcorr)=407.0 g/(m^(2)h),which is much higher than the index requirement.When the simulated fresh acid temperature was 100℃,pitting nu-cleation occurred on the material surface.As the temperature increased,the pitting sensitivity gradually increased.In the residual acid environ-ment at ultra-high temperature of 180℃,both C110 and P110 materials suffered extremely severe corrosion.Furthermore,the corrosion inhib-itor in the acidizing fluid component was obviously ineffective under high temperature conditions,resulting in serious corrosion damage to the pipes in the residual acid flowback environment.The optimized modified manene alkali acidizing corrosion inhibitor significantly slowed down the corrosion rate of the material through the formation of a multilayer adsorption film,and the corrosion inhibition rate was 89.4%in a high temperature fresh acid environment at 180℃.