Jars for Wellbore Operations

Abstract

An example of an apparatus for jarring a wellbore tool from an obstruction includes four sub-assemblies in communication with three springs such that the springs may be compressed forcing the subassemblies to become adjacent to one another. When the springs are actuated, the sub-assembly units spring apart from one another force dislodging the lower most sub-assembly component from the obstruction.

1 . An apparatus for dislodging wireline deployed tools stuck downhole, comprising:
 a first sub-assembly with an upper member secured to the lower end of a wireline;   a second sub-assembly attached to the first sub-assembly;   the second sub-assembly comprising a first housing, a shaft, and a first spring, wherein the shaft and the first spring are inside the first housing;   a third sub-assembly comprising a second housing and second spring arrangement; and   a fourth sub-assembly attached to the third sub-assembly comprising a third housing, and a third spring;   wherein the first, second and third string are capable of storing compressive energy; and   an actuator for releasing the stored energy in the first, second and third springs downward onto the fourth sub-assembly.   
     
     
         2 . A method of dislodging a tool stuck downhole in a wellbore, comprising the method of:
 providing a jarring apparatus above and attached to the tool, wherein the jarring apparatus has a first, second, third and fourth sub-assemblies moveably connected sequentially with each other;   attaching an upper end of the first sub-assembly to a member upstream;   imparting upward force on the first, second and third sub-assemblies by pulling the upstream member towards the surface of the well;   compressing a first, and second spring located in the second and third sub-assemblies;   releasing the compressed force stored within the second and third sub-assembly downward against the fourth sub-assembly attached to the stuck tool sufficient to dislodge the stuck tool.   
     
     
         3 . An apparatus for dislodging tools downhole, comprising:
 a first attachment means for attaching to the upper end of the apparatus to a wireline cable;   a second attachment means attached to the lower end of the apparatus and attached to the upper end of a downhole tool lodged downhole;   a spring mechanism housed internally within the apparatus for storing compressional force as the length of wireline above the apparatus applies upward force on the apparatus; and   an actuating means for rapidly releasing the stored compressional force downward onto the tool lodged downhole.