Research On The Sealing Performance Of The Packer Rubber Barrel Based On The Super Viscoelastic Properties Of Rubber

As the development of oil and natural gas continues to advance deep strata and deep sea,high-temperature and high-pressure downhole environments continue to pose new challenges to downhole tools.Packer as a key layered packing tool under the well,the sealing element is prone to "shoulder protrusion" and stress relaxation during the process of setting and pressure-bearing,resulting in failure of the packer seal,downhole operations and the suspension of production wells.Therefore,the Y445-115 packer is used in this paper,which is suitable for high temperature and high pressure environment,as the research object.Based on the hyper-viscoelastic characteristics of rubber materials,the sealing performance of the packer rubber is studied in the process of setting and pressure-bearing.The specific contents as follows:(1)In order to describe accurately the mechanical behavior of rubber materials,on the basis of investigation and analysis of the hyperelastic and viscoelastic mechanical properties and constitutive model of rubber materials,combined with the requirements of the function of the packer rubber,The uniaxial tension,uniaxial compression,and compressive stress relaxation experiments of three types of rubber materials of Y445-115 packer are used to obtain the hyperelastic and viscoelastic constitutive equations at different temperatures,according to stress-strain,stress-time experimental data of the rubber.And through the comparison of the numerical simulation data and experimental data of the rubber test pieces,the rationality of the constitutive parameters are verified,which lays a theoretical foundation for the simulation analysis of the sealing performance of the packer rubber.(2)Based on the contact stress,contact length and Mises stress,the normal contact force is added as an evaluation index,which provided an evaluation method for a more comprehensive and accurate evaluation of the sealability and reliability of the packer rubber.(3)Based on the hyperelastic properties of rubber materials,the effect of the wall thickness of the casing,the geometric parameters of the rubber,the position and size of the the outburst prevention device,and the temperature on the sealing performance of the rubber is performed for with single-rubber sealing in the setting stage.The influence of the combinations of the hardness of the rubber,the temperature,and loading modes on the sealing performance is performed for the packer with three-rubber sealing in the setting stage.It provides guidance for the optimal design and selection of construction methods for the rubber and outburst prevention device.(4)Based on the viscoelastic properties of rubber materials,the effects of hardness,temperature,and load of the rubber during the pressure-bearing period on the stress relaxation of the packer rubber are studied by converting the pressure load equivalent to the displacement load.Improvement measures have been proposed to avoid the sealing failure of the rubber.In this paper,through the experiment of the hyper-viscoelastic mechanical properties of the rubber material of the rubber at different temperatures is conducted,the sealing performance of the packer rubber in the setting and pressure-bearing stage is studied by using ABAQUS finite element software.The research results provide the theory and method for the design and optimization of the packer rubber and the prevention of the sealing failure.It is of great significance to improve the working performance of the packer.