CPC E21B 31/1135 (2013.01) | 19 Claims |
1. A fishing jar, comprising:
an outer housing that is configured to connect to a work string;
a mandrel positioned at least partially within the outer housing and having a fish end configured to engage a fish, the mandrel and the outer housing defining an annulus therebetween;
an anvil coupled to or integral with the mandrel;
a hammer coupled to or integral with the outer housing; and
a triggering mechanism positioned in the annulus so as to partition the annulus into a first chamber and a second chamber, the first and second chambers separated axially apart and in fluid communication via the triggering mechanism, wherein the triggering mechanism is configured to:
permit hydraulic fluid to flow from the first chamber to the second chamber at a first rate in response to pressing the outer housing to move toward the fish end of the mandrel during a downstroke of the outer housing, until the outer housing reaches a trigger position relative to the mandrel; and
permit the hydraulic fluid to flow from the first chamber to the second chamber at a second rate that is greater than the first rate after the outer housing reaches the trigger position until the hammer impacts the anvil at an end of the downstroke.
|