烟道气驱油过程中N80钢的腐蚀规律实验研究

Experimental study on the corrosion law of N80 steel during the process of flue gas flooding

随着注烟道气驱油技术应用的增多,烟道气对油井管柱的腐蚀问题日益突出。利用烟道气腐蚀测试装置模拟高温高压条件进行N80钢腐蚀实验,通过X射线衍射仪、扫描电子显微镜和能谱分析仪,分析腐蚀产物的成分和微观形貌,并研究温度、压力、流速、O_2和SO_2含量等对N80钢腐蚀速率的影响。结果表明:在模拟高温高压烟道气动态腐蚀环境下,随着时间的延长,腐蚀速率快速下降,72 h后趋于平缓;N80钢腐蚀产物成分主要为FeCO_3,Fe_3O_4和Fe_2O_3,腐蚀产物覆盖不完整,形态呈环形,排列无序。温度小于60℃时随着温度升高腐蚀速率变大,60℃时达到最大值,随后开始减小;压力增大,溶液中的碳酸浓度升高,腐蚀速率增大;流速和O_2体积分数增加,腐蚀速率增加;随着SO_2含量的增加,腐蚀速率呈先下降后增大的趋势。

As the technology of flue gas flooding is increasingly used,the severe corrosion of the flue gas on the wellbore arises becomes more important.Corrosion experiment on N80 steel was conducted at simulated high temperature and high pressure using the flue gas corrosion testing device.The composition and morphology of the corrosion product were ana?lyzed by X-ray diffractometer,scanning electron microscope and energy spectrometer.The effect of temperature,pressure,flow velocity and O2 and SO2 content on the corrosion rate of N80 steel was studied.The results show that the corrosion rate decreases fast with the increase of time and gradually reaches to a stable state after 72 h under the simulated dynamic corro?sion environment of flue gas at high temperature and pressure.The corrosion product of N80 steel is mainly composed of FeCO3,Fe3O4 and Fe2O3.The corrosion product was arranged disorderly with incomplete coverage and annular distribution.The corrosion rate increases with temperature when the temperature is lower than 60℃and reaches to the maximum at 60℃.When the pressure and the concentration of carbonic acid increase,the corrosion rate increases.With the increase of flow rate and oxygen content,the corrosion rate increases.With the increase of SO2 content,the corrosion rate shows a trend of decreasing first and then rising.