特殊螺纹石油套管接头密封结构优选

摘要

为了保证石油套管接头在高温、高压及强腐蚀工作环境下的密封完整性,采用金属对金属的密封方式代替橡胶密封.阐述了金属对金属密封的密封机理,根据厚壁圆筒弹性力学理论,推导出了石油套管接头锥形密封面最大过盈量的计算方法.利用有限元分析软件Marc建立石油套管接头的二维轴对称模型,分析了不同过盈量下密封面锥度和扭矩台肩角度对接头密封性能的影响,并对密封结构参数进行优化.采用有限元法与全尺寸试验相结合的方法验证石油套管接头在机紧、机紧+拉伸、机紧+拉伸+内压3种工况下的密封性能,结果表明该石油套管接头满足密封要求,在机紧+拉伸工况下接头的密封强度最差,设计时应优先考虑该工况.研究结果对特殊螺纹接头的开发和使用具有较高的参考价值.%To ensure the sealing integrity of casing connection in high temperature, high pressure and highly corrosive working environment, metal-to-metal sealing method is used instead of rubber sealing.The sealing mechanism of metal-to-metal seal has been described.Based on the theory of elasticity of thick-walled cylinder, the calculation method of the maximum interference of conical sealing surface of casing connection has been deduced.The finite element analysis software Marc was used to establish the 2-D axisymmetric model of the casing connection to study the influence of the sealing surface taper and the torque shoulder angle on the sealing performance of the connection, and to optimize the parameters of the sealing structure.The sealing performances of casing connection under the conditions of tight, tight+tension, tight+tension+internal pressure have been verified by the method of finite element method and full-size test.The results show that the casing connection meets the sealing requirements.The sealing strength of the connection is the worst in the tight+tension conditions, thus the design should give priority to this condition.The study results could provide references for the development and application of premium thread connection.