1. FIELD OF THE INVENTION
The present invention relates generally to downhole equipment for subterranean wells and in particular to a selective locking device, a running tool for emplacing the locking device at a selected location along a well conduit, and a retrieving tool for removal of the emplaced locking device.
2. DESCRIPTION OF THE PRIOR ART
Typically, a tubing string of a subterranean well is constructed with a plurality of landing nipples located at predetermined locations along the tubing. For example, landing nipples are incorporated into the tubing at locations where there is a present or future need for a well accessory such as a pressure equalization device or a flow control valve. These landing nipples are typically constructed with a restricted portion, or seal bore, having an inner diameter less than the inner diameter of the tubing, and a recessed portion, located above the restricted portion, with a diameter greater than the tubing diameter.
The well accessories are attached to a locking device which is subsequently lowered down the tubing and emplaced within a selected landing nipple by using a running tool. The running tool is connected to a conventional set of jars and wireline which are utilized to apply the requisite manipulative forces to the running tool for emplacing the locking device within the selected landing nipple.
Some prior art locking devices include expandable locking dogs which can be set to one of the three following positions: (1) a retracted position wherein the outside diameter of the dogs permit the locking device to pass down through the seal bore portions of each landing nipple; (2) a partially expanded, or no-go position wherein the dogs are expanded to enable the locking device to move through the tubing, but prevents the locking device from passing through the seal bore portion of a nipple; and (3) a fully expanded, or locked position, wherein the dogs are expanded within the recessed portion of a nipple to lock the device.
One method by which prior art locking devices are emplaced within a target landing nipple includes the steps of (1) lowering the running tool and locking device in the retracted position down the tubing through the target landing nipple; (2) pulling the running tool and locking device up through the target nipple to set the locking dogs to a no-go position; and (3) jarring down on the running tool to expand the dogs to a locked position within the recessed portion of the target nipple.
A prior art locking device which is set to the no-go position before reaching the target nipple is disclosed in U.S. Pat. No. 3,670,821 to Tamplen. In the Tamplen apparatus, the running tool and the locking device are run down the the tubing with the locking dogs in the retracted position until the locking device is positioned just above the target landing nipple. The running tool is then manipulated via a wireline and a set of jars to set the dogs of the locking device to a no-go position. The locking device is then lowered to locate in the target nipple where the dogs are expanded to a locked position as the running tool is pulled upwardly to retrieve the tool from the tubing.