316L不锈钢在模拟含二氧化碳原油中的耐腐蚀性能

为了进一步掌握316L不锈钢的适应性,以试验点CO2驱油后采出介质为主要溶液,采用高温高压反应釜,对316L不锈钢挂片的腐蚀规律进行了研究。以Cl-质量浓度、Ca2+质量浓度、CO2分压、温度、流速及油水比作为影响因素开展试验,并利用电子显微镜和电化学工作站对试验范围内腐蚀速率最高的挂片形貌和电化学腐蚀特征进行观察分析。试验结果表明:在Cl-质量浓度为3000~50000 mg/L、Ca2+质量浓度为100~6000 mg/L、CO2分压为0.15~0.75 MPa、温度为15~55℃、流速为0~0.5 m/s以及20%、85%两种含水率条件下,316L不锈钢的腐蚀速率均在10-3~10-2 mm/a数量级之间变化。通过电镜扫描和能谱分析发现,试件中耐腐蚀元素Mo的质量分数略高于最低限,在Al杂质较多的部位,316L不锈钢出现了腐蚀轻微的开口型点蚀坑,表明316L不锈钢在试验范围内具有很好的耐全面腐蚀能力,但点蚀问题不能忽视,试验用316L不锈钢中Cr、Ni、Mo的质量分数均略微高于最低限,建议在选材过程中对有利微量元素的质量分数给予关注。

Corrosion resistance of 316L stainless steel in simulated CO2-bearing crude oil

In order to further master the adaptability of 316 L stainless steel,the corrosion law of 316 L stainless steel coupon was studied in high-temperature and high-pressure reaction kettle by taking the medium produced at the test point after CO2 flooding as the main solution.The tests were carried out by taking Cl-mass concentration,Ca2+mass concentration,CO2 partial pressure,temperature,flow speed and oil-water ratio as the influencing factors,and then the morphology and electrochemical characteristics of the coupon with the highest corrosion rate in the test range were observed and analyzed using the electron microscope and electrochemical workstation.The test results show that under the Cl-mass concentration of 3000-50000 mg/L,the Ca2+mass concentration of 100-6000 mg/L,the CO2 partial pressure of 0.15-0.75 MPa,the temperature of 15-55℃,the flow speed of 0-0.5 m/s and the water cut of 20%and 85%,the corrosion rate of 316 L stainless steel changes in the order of magnitude of 10-3-10-2 mm/a.Electron microscope scanning and energy spectrum analysis reveal that the mass fraction of the corrosion resistant element Mo in the test specimen is slightly higher than the low limit and open pitting pits with slight corrosion appear in the 316 L stainless steel in the parts with more Al impurities.It is indicated that 316 L stainless steel has good comprehensive corrosion resistance in the test range,but the problem of pitting corrosion shall not be ignored.The mass fractions of Cr,Ni,and Mo in the 316 L stainless steel used in the test are slightly higher than the low limits,so it is recommended to pay attention to the mass fraction of favorable trace elements in the process of material selection.