Apparatus for releasing a pipe string from an object stuck downhole by continuously applying tension to said apparatus

摘要

A tension actuated device is adapted to be connected between a pipe string and an object stuck downhole in a wellbore and does not disconnect the pipe string from the object in response to a transient or temporary shock load that is temporarily applied to the pipe string. Rather, the tension actuated device selectively disconnects the pipe string from the object stuck downhole by continuously applying a pulling force of a predetermined magnitude to the device via the pipe string for a predetermined period of time. The tension actuated device includes an inner member adapted to be connected to an object stuck downhole, an outer member connected to the inner member and adapted to be connected to the pipe string, and a compressible material disposed between the inner and outer members, the compressible material being compressed and the inner member being disconnected from the outer member when a pulling force of predetermined magnitude is continuously applied to the outer member via the pipe string for a predetermined period of time. Transient loads cannot release the inner member from the outer member of the device because typical transient loads do not apply a force, of the predetermined magnitude, to the pipe string for a long enough period of time.