Abstract: A locking system which includes landing nipples connectable in a well flow conduit and a lock mandrel to which well flow control devices are connectable. The landing nipples have an unrestricted full bore flow passage with profiled locking and locating recesses having no square shoulders in the flow passage The lock mandrel may be lowered through full bore landing nipples and operated to automatically locate in the full bore landing nipple in which the lock mandrel is to be operated to lock and expand a seal system to sealingly engage the landing nipple. The lock mandrel employs locking keys having no square shoulders. The automatic locator device has locating keys having no square shoulders, which position the lock mandrel in the landing nipple. After operating, the lock mandrel is releasably retained locked and sealed in the landing nipple.

Abstract: A system and apparatus useful in establishing a metal to metal seal between members in wells. A milling tool is used to cut and/or finish a seat on a shoulder in pipe or tools in the well, which will mate and seal with metal seal surfaces on seal units lowered into the well. One seal unit has elastomeric seals in addition to the metal seals.