注减氧空气驱油对不同管材的腐蚀行为分析

Analysis of Corrosion Behavior of Oil Flooding by Deoxygenated Air Injection on Different Pipe Materials

为了扩展注减氧空气驱油的适应范围,降低气驱腐蚀对油田生产的影响,采用灰色关联分析法确定地面和井筒管线腐蚀主控因素,利用挂片失重法衡量不同氧含量下、不同管材的腐蚀速率及制气成本的关系,通过宏观观察、扫描电镜、能谱分析、激光共聚焦显微镜等手段,考察了无水和气水混注工况对腐蚀类型和腐蚀发展的影响,统计了两种工况下的均匀腐蚀速率和点蚀速率,并对3种管材的腐蚀机理进行分析。结果表明,注减氧空气驱油腐蚀的主控因素为氧含量,同时受温度、压力的影响程度也较大;将临界氧含量控制在6%左右,可以兼顾安全、经济和腐蚀控制的要求;20^(#)、N80和13Cr等在气水混注工况下的腐蚀程度较重,以局部腐蚀和点蚀为主;且该工况不影响腐蚀产物类型,只影响腐蚀产物多少;无水和气水混注工况下的点,蚀速率均较大,在含水、高温、高压等作用的耦合下存在一定的穿孔风险。

In order to expand the adaptation range of deoxygenated air flooding and reduce the influence of gas flooding corrosion on oilfield production,the main controlling factors of surface and well bore pipeline corrosion are determined by the grey correlation analysis method,and the relationship between corrosion rate and gas production cost of different pipes under different oxygen content is measured by the hanging piece weight loss method.The influence of water-free and gas-water mixed injection conditions on corrosion type and corrosion development is investigated by macroscopic observation,scanning electron microscopy,energy spectrum analysis,laser confocal microscope,and other means.The uniform corrosion rate and pitting corrosion rate under two working conditions are calculated,and the corrosion mechanism of three kinds of pipe materials is analyzed.The results show that oxygen content is the main controlling factor affecting deoxygenated air flooding corrosion,temperature and pressure also have great influence.Controlling the critical oxygen content at about 6%can meet the requirements of safety,economy,and corrosion control.The corrosion degree of 20^(#),N80,and 13Cr is relatively serious under gaswater mixed injection conditions,mainly local corrosion and pitting corrosion.This working condition does not affect the type of corrosion products,only the amount of corrosion products.The pitting rate is relatively high under water-free and gas-water mixed injection conditions,and there is a certain risk of perforation under the coupling effects of water,high temperature,and high pressure.