Abstract: The invention relates to a safety packer assembly for use in a cement-lined pipe. The assembly provides for the use of a packer body which carries one or more resilient collars that expand in response to a compression force created by rotation of an upper part of the packer body. A safety valve is provided in the upper part of the packer body to prevent escape of the downhole pressure. A safety centralizer is detachably secured to a lower part of the packer body, the centralizer being provided with a plurality of arcuate resilient members which extend along the length of the centralizer body and frictionally contact the wall of the cement-lined pipe to maintain the packer body in its predetermined position within the pipe and resist rotation of a lower part of the packer body when the upper part is rotated.

Abstract: The invention relates to a seal-sub packer assembly which is formed by a two-mandrel packer and a setting tool which positions the packer within the casing. A lower mandrel of the packer is provided with internal threads for engagement with the setting tool, thereby preventing premature setting of the packer. The exterior surface of the lower mandrel carries one or more sealing members which are compressed and forced to expand horizontally when the upper mandrel slides downwardly, shearing shear screws in response to a downward force acting on the setting tool. In an alternative embodiment, a liner hanger is secured to the lower mandrel, the liner hanger carrying an annular band with an inverted J-shaped slot through which a pin extends. When the body of the packer assembly is rotated in a predetermined direction, the guide pin extending through the J-slot resists premature setting of the packer.