Study On The Performance Of O-ring For Packer

Packer is a kind of downhole tool commonly used in oil and gas well operation.As a key component in the packer,the performance of the O-ring affects the safe and effective operation of the downhole tools.In the oil and gas completion operation,it is found that the sealing design parameters selected by the O-ring in the actual application are not suitable,the comprehensive performance is bad,and the reliability is low,which will cause the O-ring to be vulnerable and the seal failure,which causes the tools not easy to equipment,and the well is not smooth and so on,which will bring adverse effects to the completion operation.Therefore,the research on the performance of O-ring for the packer is carried out to provide a theoretical reference for the selection and design of the seals.It is helpful to select the O-shaped seal reasonably and improve the safety and reliability of the packer's downhole operation.Firstly,based on the structure and working principle of the O-ring of the packer,the failure forms and criteria of the O-ring are expounded,and the relative standards at home and abroad are compared and analyzed in the light of the design parameters of the seal.Then,the L₈?4×2?orthogonal test scheme was designed for different specifications of O-ring,and the corresponding test tooling was manufactured and 72 groups of static seals and24 groups of friction tests were carried out under different working conditions.The results showed that under the different compression rates,the constant temperature,high temperature liquid and gas static sealing performance of the O-ring were stable when the 35MPa pressure was under pressure.The friction force increases with the compression rate.The analysis of the difference and variance shows that the inner diameter of the cylinder,the diameter of the piston and the bottom diameter of the groove are the significant factors that affect the friction performance.When the compression rate of the three O-rings is less than 16.51%,13.07%and 14.51%,the motion friction can meet the operating load allowed in the field operation.At the same time,the finite element software is used to simulate the static seal and motion process of O-ring.It is shown that the maximum contact stress increases but not significant when the compression rate increases.The compression ratio is more significant,and the compression ratio of medium pressure is more significant to the maximum Von Mises stress and the maximum contact stress.The maximum Von Mises stress,maximum contact stress and maximum shear stress all increase approximately linearly with the compression rate,and the compression rate is certain,and the maximum Von Mises stress,the maximum contact stress and the maximum shear stress at the time of movement are all larger than the results of pre compression.Finally,the results of the comprehensive test and the finite element simulation show that the compression ratio of the three specifications O-ring of the packer is 10%¹6%,10%¹3%and 10%¹4%,which is smaller than the international standard,and the friction force decreases more than 30%when the compression ratio is larger than the international standard,and it still has the 35MPa density.Sealing ability meets the working condition requirements of downhole tools,and gives the recommended design value of the seal groove.The design and selection program of O-ring are compiled,and the database of technical parameters is perfected.Under the three standards system,ISO,Parker and recommendation system,the sealing parameters that meet the requirements are selected.