| CPC E21B 31/113 (2013.01) [E21B 34/08 (2013.01)] | 4 Claims |

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1. A method of employing a jarring device in a well comprising:
a) applying an upward force from the surface on a jarring device disposed in a well, the jarring device comprising:
a housing;
an axially movable mandrel positioned within the housing;
a dog clutch surrounding the mandrel, the dog clutch comprising a plurality of segmented release lugs having more than one mating projection which are non-uniformly spaced apart from each other;
a trigger sleeve surrounding the dog clutch;
the dog clutch and trigger sleeve having complementary surfaces which when in alignment will cause the dog clutch to release the mandrel;
a spring positioned within the housing; and
a hydraulic chamber and a piston located in the hydraulic chamber and surrounding the mandrel and, the piston being positioned between the spring and dog clutch;
b) moving the mandrel axially within the housing in an upward direction;
c) holding the mandrel with the dog clutch;
d) resisting the movement of the mandrel by a force of the spring and a hydraulic pressure generated by the piston compressing a fluid in the hydraulic chamber;
e) releasing the mandrel with the dog clutch when the complementary surfaces of the dog clutch and trigger sleeve come into alignment; and
f) striking an anvil on the housing with a hammer surface of the mandrel.
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