RELEASABLE CONNECTION FOR A DOWNHOLE TOOL STRING

A releasable connection for a downhole tool string is provided, having a first part with a connection profile and a second part with a releasable engagement profile that releasably engages the connection profile of the first part. The second part also has a locking piston, the locking piston moving axially along the second part between a locking position that locks the releasable engagement profile into engagement with the connection profile of the first part and a release position that permits the releasable engagement profile to release the connection profile of the second part, an expansion chamber in fluid communication with the locking piston, and a source of fluid pressure in communication with the expansion chamber, wherein, upon activation, the source of fluid pressure applies fluid pressure to move locking piston from the locking position toward the release position.