Combination seal is one of the most important downhole tools in petroleum engineering. In order to improve the performance of the packer, the combined type consists of a pressed rubber tube and an expanded rubber tube.

In order to understand the sealing performance of the combined seal rubber tube, the stress of the double expansion combined rubber tube and the expansion and contraction combined rubber tube and the contact pressure of the rubber tube and the rubber tube were compared and analyzed by using ABAQUS finite element software. The analysis results show that under the 15 MPa set sealing pressure, the two rubber sleeves can effectively contact with the hose, and the contact pressure between the rubber sleeve and the inner wall of the hose is greater than that of a single rubber sleeve, so the combination can really improve the sealing and sealing effect. Among them, the sealing pressure difference of the expansion and pressure combination is the highest, which is 50% higher than that of the single expansion. Double expansion lower rubber sleeve and expansion pressing expansion rubber sleeve should be properly strengthened and thickened to improve the working stress of the rubber sleeve.

Combination seal is one of the most important downhole tools in petroleum engineering, which is widely used in various production links of oil and gas exploration and development. It is located between the tubing and the hose or between the hose and the borehole wall, and is used to seal off the annular space between the tubing and the hose or between the hose and the borehole wall. Among them, the sealing element (rubber sleeve) made of non-metallic materials such as rubber is the most important device, and there are two types of pressing rubber sleeve that relies on axial pressure to press the seal and expanding rubber sleeve that relies on radial pressure to expand the seal. With the development of petroleum engineering technology and the improvement of operating pressure, in order to improve the sealing and sealing performance, the combination of pressed rubber sleeve and expansion rubber sleeve is used, and the combined seal appears. The structure of the rubber sleeve must be reasonably designed and used within a limited pressure range, otherwise it is easy to cause damage to the rubber sleeve and loss of sealing. Because the rubber sleeve is a nonlinear material, its theoretical research is difficult, so the current use of finite element and other numerical analysis methods to analyze its related mechanical properties. The experimental data were fitted with the hyperelastic constitutive model in the ANSYS finite element analysis software, and the constitutive model that can accurately describe the stress-strain relationship of the rubber sleeve was determined, and the axial contact pressure distribution was obtained. A finite element computational mechanical model of the contact problem between the pressed and expanded components is developed, and the size of the contact pressure distribution is analyzed. The finite element software was used to analyze the influence of the working length, thickness, shoulder shape and steel cord arrangement on the force and deformation law of the expansion rubber sleeve. With the contact pressure and the volume of the rubber sleeve as the optimization target, the structure optimization design of the rubber sleeve is carried out by using the finite element method.

Whether it is a double expansion combined seal or an expansion compression combined seal, under the expansion and sealing pressure of 15 MPa, the two sealing cylinders can effectively contact the hose, and the contact pressure between the combined sealing cylinder and the inner wall of the hose is greater than that of a single sealing cylinder, so the combination It can indeed improve the sealing and sealing effect. Among them, the seal pressure difference of the expansion pressure combination seal is the highest, which is 50% higher than that of the single expansion.