Patent ID: 7753116

Claim:
A double-acting jar comprising: an inner mandrel and an outer housing; the inner mandrel being at least partially disposed telescopically within the outer housing to define a fluid chamber between the inner mandrel and the outer housing, the fluid chamber containing fluid and being sealed at an uphole end and at a downhole end; an uphole restriction and a downhole restriction spaced from one another within the fluid chamber and spaced from the uphole end and from the downhole end; an uphole valve disposed within the fluid chamber, the uphole valve having a first seating surface engageable with an uphole facing sealing shoulder in the fluid chamber to seat the uphole valve when the upper restriction slides relatively downward over at least an initial portion of the uphole valve, the uphole valve having a first exterior surface that fits with close tolerance within the uphole restriction over at least a portion of the first exterior surface; a first bypass, defined by at least one of the uphole valve, the outer housing, and the inner mandrel, is exposed when the first seating surface unseats from the uphole facing sealing shoulder; a downhole valve disposed within the fluid chamber, the downhole valve having a second seating surface engageable with a downhole facing sealing shoulder in the fluid chamber to seat the downhole valve when the downhole restriction slides relatively upward over at least an initial portion of the downhole valve, the downhole valve having a second exterior surface that fits with close tolerance within the downhole restriction over at least a portion of the second exterior surface; a second bypass, defined by at least one of the downhole valve, the outer housing, and the inner mandrel, is exposed when the second seating surface unseats from the downhole facing sealing shoulder; first jarring surfaces on the inner mandrel and outer housing respectively for jarring contact with each other during a jar in a first direction; and second jarring surfaces on the inner mandrel and outer housing respectively for jarring contact with each other during a jar in a second direction; the uphole restriction and downhole restriction being separated such that when the downhole restriction slides relatively upward over the initial portion of the downhole valve to seat the downhole valve, at least a portion of the uphole restriction extends upwardly beyond a downhole end of the uphole valve sufficient to allow a jar in the first direction to be carried out, and when the uphole restriction slides relatively downward over the initial portion of the uphole valve to seat the uphole valve, at least a portion of the downhole restriction extends downwardly beyond an uphole end of the downhole valve sufficient to allow a jar in the second direction to be carried out.