集输油环境氟橡胶O形圈老化行为实验研究*

为研究氟橡胶O形圈在集输油环境中的老化行为特征，以长庆油田使用的氟橡胶O形圈(位于非金属复合管连接接头处)为研究对象，采用宏观与微观相结合的方法，通过挂片实验分析氟橡胶O形圈在不同介质（采出油，采出水）、温度（25，50 ℃）、压力条件（0.1,4,6 MPa）下老化后的形貌、质量、拉伸性能及硬度。结果表明:采出油、采出水均能引起O形圈发生溶胀，从而降低O形圈的强度、韧性、硬度；采出水引起的溶胀显著高于采出油更易导致O形圈表面产生坑洞缺陷；渗透速率随温度升高而急剧增加，压力对渗透速率的影响不明显；硬度降低较小，最大降幅为4.17%。结合现场服役813 d的密封圈SEM形貌，证实集输介质渗透会引起氟橡胶圈溶胀、导致表面产生坑洞等缺陷。

Experimental study on aging behavior of fluororubber O-ring in oil gathering and transportation environment

In order to clarify the aging behavior characteristics of fluororubber O-ring in the oil gathering and transportation environment,aiming at the fluororubber O ring adopted in the connection joint of non metal composite pipe in Changqing oilfield,the appearance,mass,tensile properties and hardness of fluororubber O ring after aging in two media of produced crude oil and produced water under different temperature and pressure conditions,i.e.,25,50 ℃,0.1,4, 6 MPa were analyzed through the hanging piece experiments by the combined macro and micro method.The results showed that the swelling of O ring could be caused by both the produced crude oil and water,which resulted in the decrease of strength,toughness and hardness.The swelling caused by the produced water was significantly higher than that of produced crude oil,which was easier to cause the pit defects on the surface of O ring.The penetration rate increased dramatically with the increase of temperature,while the influence of pressure on the penetration rate was not obvious.The hardness decreased slightly with a maximum decreasing amplitude of 4.17%.Combined with the SEM appearance of sealing ring which had been used for 813 days in the field,it was confirmed that the swelling and the defects such as pits on the surface of the fluororubber O ring were resulted by the penetration of gathering and transportation medium.