Study on Sealing Performance of Packers in Deformed Casing of Ultra-Deep Horizontal Wells

Abstract Aiming at the problem of packer sealing failure caused by casing deformation in ultra-deep horizontal wells and intervals with complex crustal stress, this study reveals the characteristics of casing elliptical deformation under the combined action of non-uniform crustal stress and formation creep. Based on the theory of large deformation of rubber and elastic mechanics, the three-dimensional numerical model of the packer sealing mechanism considering casing deformation is established. Using sealing contact strength as the evaluation index, the evolution law of rubber cylinder deformation, stress distribution, and sealing performance indices of the packer under different elliptical aspect ratios and pressure loads are analyzed. The research shows that elliptical deformation results in an “elliptical” distribution of contact stress between the rubber cylinder and the casing, with contact stress in the minor axis region significantly higher than that in the major axis region. When the aspect ratio is ≤ 1.02, the packer can maintain effective sealing through adaptive deformation of the rubber cylinder. When the aspect ratio is ≥ 1.04, the circumferential stress non-uniformity intensifies, and the contact stress in the major axis region is insufficient, resulting in a significant increase in the risk of sealing failure. The research results provide a theoretical basis and engineering guidance for the optimal design and sealing technology of packers under complex well conditions.