Reliability and Sensitivity Analysis of Y361 Packer Combination Rubber Tubes

ABSTRACT

As a core component of downhole annular sealing tools, packers play a crucial role in oil well production. This paper examines the reliability and sensitivity of the Y361 packer's combination rubber tubes sealing system through finite element method simulation, with an emphasis on its sealing mechanism. An axisymmetric finite element model incorporating geometric, material, and state nonlinearities is developed for the simulation. Reliability and sensitivity analyses are performed by integrating Stress‐Strength Interference Theory and response surface methodology, considering manufacturing tolerances and variations in operating conditions. Under seated sealing conditions with axial compression, the combined rubber tubes exhibit progressive radial expansion, producing a casing contact stress distribution characterised by five local peaks corresponding to the contact regions of the six rubber tube units. Compared with the conventional single rubber tube packer, the sealing capability of the combination rubber tubes is significantly enhanced; the maximum contact stress is increased by 56.3%, and the average contact stress is increased by 10.1%. Reliability assessment indicates that the sealing system achieves a high operational reliability of 99.4233% based on the shear strength criterion, and a reliability of 100% when using the maximum contact pressure criterion. Sensitivity analysis reveals that the casing's inner diameter exerts the most significant influence on the maximum contact pressure and shear stress, followed by the friction coefficient, rubber tube length, and material constants. This study provides theoretical guidance and practical insights for optimizing the design and manufacturing of packer combination rubber tubes.