Importance

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Abstract

A downhole activated circulating sub is adapted to be interconnected between various tools installed on coiled tubing and placed into a wellbore; for example, between a coiled tubing/measurement while drilling tool and a downhole motor/drill bit for drilling a wellbore. The circulating sub can be repeatedly set and reset while the circulating sub is disposed in the wellbore. As a result, it is not necessary to retrieve the circulating sub to the wellbore surface for the purpose of resetting the sub. The circulating sub includes a latch mechanism which locks and latches the sub in either a set condition or a reset condition when a fluid is pumped through the circulating sub. When fluid flow through the circulating sub stops, the latch mechanism is unlocked and the circulating sub can change between the set condition and the reset condition. When fluid flow stops and the latch mechanism is unlocked, in response to a pull or a push on the coiled tubing, the coiled tubing will move laterally a distance of about 11/2 inches which will enable a mandrel to move. When the mandrel moves, a second pair of upsets on a mandrel in the circulating sub moves from a first position surrounding a first upset on an intermediate member to a second position surrounding a second upset on the intermediate member. This movement of the mandrel changes the condition of the circulating sub between the set condition and the reset condition. When fluid flow through the circulating sub restarts, the latch mechanism once again latches the circulating sub in either the set or reset condition.

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First Claim