Research on the Influence of Stress Relaxation on the Sealing Performance of the Packer Under HTHP

As a key tool in hydraulic fracturing, the packer plays a vital role in the process of unconventional oil and gas production. Its sealing performance has a significant impact on production. The packer is in high-temperature and high-pressure (HTHP) environment for a long time. It is easy to produce significant stress relaxation, which affects the sealing performance of the packer. In this paper, rubber foundation tests at 150 degrees C temperature were carried out. The hyperelastic-viscoelastic model of the rubber material was determined. The influence of the stress relaxation on its sealing performance was investigated. In addition, the effects of setting load, height, inner diameter, and outer diameter on the sealing performance were systematically investigated. The findings show that under HTHP, the stress relaxation phenomenon leads to a 6.9% decrease in peak shear stress, 10.3% decrease in peak von Mises stress, and 6.7% decrease in peak contact stress, reducing the risk of damage to the packing element and leading to a decrease in its sealing performance. In addition, it was found that increasing the setting load can significantly increase the contact stress, which also increases the risk of damage. When increasing the height, the peak shear stress and peak contact stress do not change much but can significantly reduce the peak von Mises stress. When increasing the inner diameter, the peak shear stress and peak contact stress show a trend of first increasing and then decreasing, and the peak von Mises stress has been decreasing. Increasing the outer diameter can better improve the force situation, increase the contact stress, and make the contact stress distribution more uniform. It is necessary to consider the influence of stress relaxation on the sealing performance of the packer under HTHP; meanwhile, this paper has guiding significance for the design of packer structures.