高低温冲击条件下CO_2驱注入管失效危险性试验研究

Experimental study on failure risk of CO_2 flooding injection pipe under repeated high and low temperature impacts

为预防CO_2驱油过程中CO_2注入管受高低温冲击而发生沸腾液体扩展蒸气爆炸(BLEVE)事故,以某油田CO_2驱使用的P110钢注入管为研究对象,借助高低温冲击试验箱及自主设计的CO_2爆炸测试系统,研究在CO_2介质低温及地热反复作用下缺陷油管BLEVE失效的行为,并通过金相分析和力学测试,研究高低温冲击对CO_2驱注入管失效危险性的影响。结果表明,高低温反复冲击后缺陷油管爆炸破损程度加剧,且失效压力明显下降;力学性能和金相分析结果显示,高低温反复冲击使油管内马氏体转变为索氏体,油管屈服强度、抗拉强度和硬度普遍降低,在CO_2高压注入过程中油管BLEVE失效的危险性显著增大。

In order to prevent injection pipe explosion of BLEVE caused by high and low temperature impact in the process of CO2 flooding, P110 steel tubes and the high and low temperature impacts test device were used, an CO2 explosion system was also designed. The explosion process and BLEVE failure behavior of defected pipe under the low temperature impact from CO2 and the high temperature impact by subterranean heat were experimentally researched. The effect of high and low temperature impact on the material properties of pipe was also studied by mechanical testing and metallographic analysis. The experimental results show that the defective pipes under repeated high and low temperature impacts failed with larger fractures and lower burst pressures and the martensite inside the pipe changed into sorbite. It can be concluded that the repeated high and low temperature impacts reduced the yield strength, tensile strength and hardness of the pipe and increased BLEVE explosion risk during the CO2 injection process with high-pressure.