Pre-formed stress rings for inflatable packers

摘要

An inflatable packer apparatus for use in a well bore has pre-formed metal stress rings surrounding the respective opposite end portions of the packer element. The stress rings are machined to initially have conical outer surfaces, and then are outwardly stressed beyond their yield strengths to obtain plastic deformation such that such outer surfaces are generally cylindrical so that the packer element can be inflated to higher pressures.