Patent ID: 6230798
Filing Date: 2001-05-15
Classification: E21B

Abstract:
A hydraulic anchor packer for use in a well bore comprising:in inflatable packer element incorporating a cylinder and an elastomer sleeve provided on the exterior surface thereof, the elastomer sleeve being retained by retaining means adjacent the cylinder at the end portions of the sleeve but free of the cylinder intermediate the end portions;an aperture defined by the wall of the cylinder for connecting the exterior of the cylinder in a region where the elastomer sleeve is free thereof to the interior of the cylinder;means for releasably connecting the packer element to a well bore string;means for causing fluid from within the well bore string to flow through the aperture and between the elastomer sleeve and exterior surface of the cylinder to radially expand the elastomer sleeve; andmeans for trapping fluid which has flowed into the chamber between the elastomer sleeve and the cylinder to prevent relaxation of the elastomer sleevethe means for trapping fluid comprises a piston having a first position in which the aperture is in communication with the interior of the well bore string and the packer element is connected to the well bore string, and a second position in which the aperture is isolated from the interior of the well bore string and the packer element is released from the well bore string, and means are provided for shifting the piston from the first position to the second position when the pressure differential across the piston exceeds a predetermined value to trap fluid in the chamber and release the packer element form the well bore string.