高温高压高含CO2环境下两种氟橡胶密封可靠性评价

Evaluation on Sealing Reliability of Two Kinds of Fluorinated Rubber in High Temperature,High Pressure and High CO2 Environment

目的研究两种氟橡胶O型圈在总压为25 MPa,CO2体积分数为5%,温度为120℃,液相介质Cl‒质量浓度为7000 mg/L的高温高压高含CO2工况下的密封可靠性。方法通过高温高压釜模拟井下实际工况,采用自研橡胶O型圈密封装置实现试样的承压状态,以物理性能、腐蚀形貌和抗渗透性能为考察指标,对两种氟橡胶O型圈的耐蚀性能和密封性能进行测试评价。结果氟硅橡胶O型圈在承压状态下腐蚀后,拉伸强度由18.1 MPa下降为13.4 MPa,拉断伸长率由172.8%下降为151.9%。AFLAS橡胶O型圈在承压状态下腐蚀后,拉伸强度由21 MPa下降为14.6 MPa,拉断伸长率由277%下降为212.3%,硬度从84HA下降为75.5HA,表面破损严重。两种橡胶O型圈抗渗透性能随压差增大、温度上升而减弱。结论承压状态下,两种橡胶O型圈性能衰减程度低于自由状态,氟硅橡胶O型圈在承压状态下表现出更好的密封可靠性。

The work aims to study the sealing reliability of two kinds of fluorosilicone O-ring in high temperature,high pressure and high CO2 environment(25 MPa,5%CO2,120℃and 7000 mg/L Cl‒).The actual conditions were simulated by the high-temperature and high-pressure autoclave.The stress state of the specimen was realized with self-grinding rubber O-ring sealing device.The corrosion resistance and sealing properties of two kinds of fluorine rubber O-rings were tested and evaluated in terms of physical properties,corrosion morphology and permeability resistance.The tensile strength of fluorosilicone O-ring decreased from 18.1 MPa to 13.4 MPa and the elongation at break decreased from 172.8%to 151.9%after corrosion under stress state.After the corrosion of AFLAS rubber O-ring under stress state,the tensile strength decreased from 21 MPa to 14.6 MPa,the elongation at break decreased from 277%to 212.3%and the hardness decreased from 84 HA to 75.5 HA.The surface damage of AFLAS rubber O-ring was serious.The permeability resistance of two rubber O-rings decreased with the increase of differential pressure and temperature.The degree of performance attenuation of two rubber O-rings under stress state was lower than that under free state.The fluorosilicone O-rings show better sealing reliability under stress state.