Abstract: A method of operating a safety joint that allows disconnection from a downhole section of a drill string without rotating the drill string. In an example class of embodiments, the innovative safety joint includes a sleeve with a j-slot that fits to a lug attached to the mandrel. A piston is attached to the sleeve. The safety joint is disconnected by first pulling up on the string to shear a set of shear pins, the upward movement also lifting the sleeve and piston. As the piston lifts, a passage through a part of the piston allows fluid to move from an upper chamber to a lower chamber. A valve prevents fluid from moving back up into the upper chamber, so that the lower chamber acts as a stop to prevent the piston and sleeve from lowering again. Downward pressure on the drill string forces a lug against the j-slot, causing the sleeve to rotate until the lug is aligned with a vertical slot of the j-slot.

Abstract: A safety joint that allows disconnection from a downhole section of a drill string without rotating the drill string. In an example class of embodiments, the innovative safety joint includes a sleeve with a j-slot that fits to a lug attached to the mandrel. A piston is attached to the sleeve. The safety joint is disconnected by first pulling up on the string to shear a set of shear pins, the upward movement also lifting the sleeve and piston. As the piston lifts, a passage through a part of the piston allows fluid to move from an upper chamber to a lower chamber. A valve prevents fluid from moving back up into the upper chamber, so that the lower chamber acts as a stop to prevent the piston and sleeve from lowering again. Downward pressure on the drill string forces a lug against the j-slot, causing the sleeve to rotate until the lug is aligned with a vertical slot of the j-slot.