1. Field of the Invention
This invention relates to a liner seal for use with a liner or gravel screen, and more particularly, to a liner seal which forms a part of a tool string and which interconnects the liner screen with a releasing mechanism on the tool string.
2. Description of the Prior Art
Positioning liner screens and packing gravel therearound in a well bore is known in the art. Typically, the liner screen is at the bottom of a tool string, releasably disposed at a point below a gravel packer. After the gravel packing operation, the gravel packer is unset, and the tool string is detached from the liner screen. The gravel pack keeps the liner screen positioned. The tool string is removed from the well, and it is then necessary to lower a liner seal into the well bore above the liner screen and the gravel pack. The liner seal is then set for sealing engagement with the well bore for preventing migration of the gravel pack up the well annulus.
The apparatus of the present invention eliminates the step of removing the drill string and lowering the liner seal in that the present invention includes a liner seal releasably attached to the tool string originally lowered into the hole. After the gravel packing operation, the liner seal can be released from the tool string and set to its sealing position. The tool string is then removed from the well, and a separate operation of lowering a liner seal after packing is eliminated. This greatly reduces the cost and time involved in a gravel pack operation.
The releasing mechanism used in the present invention is a pressure actuated, non-rotational collet releasing device. Such a non-rotational releasing mechanism is disclosed in pending application Ser. No. 756,892, assigned to the assignee of the present invention.