Unlocking packer setting method and device

Abstract

A dog sub is provided for use in an assembly for running liners with weight-set packers and/or other mechanically or hydraulically actuated devices that need to be located. The dogs are retained by a sleeve so that an applied pickup force to determine that the running string had released from the liner can be applied which even results in removal of the dog sub from the extension tube of the weight-set packer. The dogs are held in a retracted position, even if taken out of the extension tube initially. Thereafter, the dog sub is supported off the extension tube and the locking sleeve on the dogs is liberated, with the dogs inside the extension tube. A subsequent pickup force allows the dogs to move outwardly, whereupon a subsequent setdown force locates the dogs on the setting extension tube. A subsequent setdown force sets the packer and breaks a breakable member, such as a shear pin. Upon removal to the surface, surface personnel can see that a shear pin has broken to indicate that the requisite force has been applied to the weight-set packer.