Mechanical properties of adhesive interface for the expandable packer rubber with nylon 66 cord under high pressure and high temperature

Abstract

In this paper, the expandable packer rubber with nylon 66 cord was selected as research object. By carrying out a single pull-out experiment of nylon 66 cord rubber, it was gotten that the critical failure energy of the adhesive interface between the cord and the rubber matrix was 3.21 kJ/m2. The Cohesive Zone Model (CZM) was used to describe the bonding state of interface between nylon cord and rubber matrix and the debonding failure criterion was then established for the adhesive interface between nylon 66 cord and rubber matrix. The mechanical properties and working performance were analyzed systematically for the expandable packer rubber under different pressures and well temperatures. The results showed that:1) When the fracturing pump pressure was 50 MPa∼80 MPa, the shear stress of the packer rubber matrix was less than the allowable shear stress of 17.5 MPa, and the matrix didn't appear shear tearing damage. So the packer rubber filled with nylon cord could effectively protect the rubber matrix and avoid shear tear damage. 2) When the fracturing pump pressure was 80 MPa, the interface failure energy of the lower rubber was greater than the critical failure energy of 3.21 kJ/m2, and the interface debonding failure occurred between cord and matrix. 3) When the well temperature was 25 °C–175 °C, the shear stress of the rubber matrix increased with the increase of well temperature, but he maximum shear stress of the matrix was less than the allowable shear stress of 17.5 MPa. The failure energy of the adhesive interface was less than the critical failure energy of 3.21 kJ/m2. So there was no shear tear on the matrix of the rubber and the adhesive interface was well bonded. Therefore, the expandable packer rubber with nylon 66 cord could work well in a higher well temperature environment. It is concluded that the research results can provide theoretical guidance for exploring the performance of the expandable packer rubber with nylon cord.