"双碳"背景下,碳捕集、利用与封存(carbon capture,utilization and storage,CCUS)技术将发挥关键作用,其中针对CO2-EOR井中低温对封隔器及密封圈老化问题,首先建立CO2在注入井中温度分布理论模型;然后通过有限元方法建立密封圈数值模拟模型,开展不同温度下橡胶密封圈的等效应力、接触压力和真实应变的研究,并分析低温对密封圈力学性能影响和低温老化的原因.结果表明:CO2注入井中封隔器密封工作温度在其玻璃化转变温度Tg以上,正常工作不会产生低温老化;低温对注入管阀门密封圈的力学性能影响显著,较常温环境下的Mises应力和接触压力上升3～4倍.当环境温度低于Tg后,密封圈将会从高弹态转变为玻璃态,其硬度增加、弹性降低,老化程度逐渐加深,导致密封圈接触压力小于介质压力而失效.
Influence of Low Temperature on the Performance of Packer and Seal Ring in CO2-EOR Well
Under the background of"two-carbon",carbon capture,utilization and storage(CCUS)technology will play a key role.In order to solve the problem of low temperature in CO2-EOR well on packer and seal aging,a theoretical model of CO2 temperature distribution in injection well was first established.Then,a numerical simulation model of the sealing ring was established by finite element method,and the equivalent stress,contact pressure and real strain of the rubber sealing ring at different temperatures were studied,and the influence of low temperature on the mechanical properties of the sealing ring and the causes of low temperature aging were analyzed.The results show that the sealing operating temperature of the packer in the CO2 injection well is above its glass transition temperature Tg,and low temperature aging will not occur during normal operation.Mises stress and contact pressure increases 3～4 times compared with that at normal temperature,the mechanical properties of injection pipe valve seals are significantly affected at low temperature.When the ambient temperature is lower than Tg,the sealing ring will change from a high elastic state to a glass state,and its hardness will increase,elasticity will decrease,and the aging degree will gradually deepen,resulting in the failure of the sealing ring when the contact pressure is less than the medium pressure.
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