为满足海上油田集输管线的腐蚀防护需求,解决南海某油田高CO2含量、高矿化度和高流速等复杂工况下的腐蚀问题,实验室内以月桂酸及二乙烯三胺为原料合成出咪唑啉中间体,经硫脲改性和复配后获得水溶性硫脲基咪唑啉缓蚀剂。参照该南海油田工况条件开展静态挂片腐蚀评价实验并确定出产品配方,随后对该配方进行工业放大生产获得工业中试样品。通过对室内合成和工业中试的两个样品开展动态挂片腐蚀评价实验发现,两个样品对X65碳钢的缓蚀率均在98%以上。将工业中试复配的产品推广至目标油田现场进行应用,成功将平均腐蚀速率控制在0.015 59 mm/a左右,取得了良好的缓蚀效果。实践证明,水溶性硫脲基咪唑啉缓蚀剂能够很好地解决该类复杂工况条件下的油田管道腐蚀问题,具有良好的应用前景。

This paper presents the study on the corrosion protection of the gathering pipelines in offshore oil fields. The study addresses the issues of high corrosion rate under complex working conditions including high CO2 content, high salinity and high flow rate in an oilfield in the South China Sea. An imidazoline intermediate was synthesized using lauric acid and diethylenetriamine as raw materials in the laboratory. Then a water-soluble thioureido-imidazoline corrosion inhibitor was obtained after thioureid-based modification and combination. According to the working conditions of the oil field in the South China Sea, the static corrosion coupon evaluation experiment was carried out and the product formula was determined. Then, the industrial scale production of that corrosion inhibitor was used to obtain industrial pilot samples. Through the dynamic corrosion coupon evaluation experiment using the two inhibitor product samples from indoor synthesis and industrial scale pilot testing, it is found that the corrosion inhibition rates of the two samples to X65 carbon steel are above 98%. Finally, the product formulated in the industrial pilot test was extended for application to the target oil field, and the average corrosion rate was successfully controlled at about 0.0155 9 mm/a, achieving a good corrosion inhibition effect. It has been proven from actual practices that the water-soluble thioureido-imidazoline inhibitor can tackle the pipeline corrosion in oil fields under such complex working conditions and has a good prospect for wider application.