Back-off apparatus and method for retrieving pipe from wells
OwnerJack A. Henninginventor
Life of this patent
Estimating the term…
Abstract
A new and improved apparatus and method for lowering the apparatus downwardly in a drill string on a wireline to releasably engage a recess in a threaded joint or collar of the drill string to prevent further downward movement of the apparatus and to thereafter detonate an explosive by manipulating a wireline actuated jar with repeated downward blows for exerting a jarring force to the joint as a result of the explosion to release the threads at the joint upon simultaneous application of a back-off torque to the drill string. The apparatus can be released and removed from the well without breaking or damaging the collar locating and supporting portion of the apparatus.
Claims18
An apparatus for locating and applying a jarring or hammering force to a threaded connection joining sections of a string of drill pipe, comprising:
- an elongated tool means for lowering in a well from a wireline;
- supporting means with the tool means operable for allowing downward movement of the tool means through the drill string until the tool means has been raised upwardly to a releasable locking position engaging the supporting means with a threaded connection to support the tool means and to thereafter prevent further downward movement of the tool means in the drill string;
- locating means with the supporting means and operable upon an upward movement of the tool means for locating a selected connection which is to be released to position the supporting means in the releasable locking position;
- explosive means with the tool means operable by manipulation of the wireline for exerting an explosive force adjacent to the connection for imparting a jarring force to the threaded collar connection for effecting release of the threaded upper portion of the connection by reason of the explosion and a back-off torque which is applied to the drill string;
- a wireline actuated jar connected to the wireline and adapted to be manipulated by the wireline to detonate the explosive means and to impart an explosive jarring blow to the connection to be released;
- and
- said supporting means preventing downward release from the locking position during repeated jars with said wireline actuated jar to thereby assure that when the explosion detonates, it occurs in proximity to the connection to be released.
A method for locating and applying a jarring or hammering force to a threaded connection joining sections of a string of drill pipe, comprising:
- lowering a back-off apparatus having a wireline actuated jar through a drill string with a wireline;
- releasing a locking support means with the back-off apparatus from a non-engaging position for lowering through the pipe string by manipulating the wireline;
- engaging and releasably locking the support means with the back-off apparatus with a recess formed by a connection to prevent further lowering of the apparatus upon lowering of the wireline and to support the back-off apparatus with the connection to sustain repeated jars from the jar;
- and
- manipulating the wireline for discharging an explosive with the back-off apparatus for exerting the explosive force to the support means and connection to impart a jarring or hammering force to the connection through the support means for effecting release of the threaded connection when a back-off torque is applied to the drill string.
Dependencies are inferred from the claim text.