Hydraulic Disconnect

Hydraulic disconnect is a downhole tool which run into the well as part of the borehole assembly for workover or other type of works.Used for controlled disconnection of the part of the BHA below the disconnect from the BHA above the disconnect.

The disconnect occurs in the following way: at the surface a steel ball dropped inside the coiled tubing, which is pumped down the coiled tubing till landing of the ball in the disconnect ball seat.

After landing the ball to the seat of the disconnect, the ball closes the flow path and the pressure begins to increase above the ball. At a certain point, when the pressure exceeds the cutting pressure of the pins, the pins are cut off and the top and bottom of the disconnect are undocked.

The disconnect is used in any downhole operation, where is a risk of BHA stuck. Thus, in the case of stuck, controlled undocking with a disconnect - less risky operation than trying to free the BHA by pulling by the CT injector, because an overpull of the CT may lead to its breakage.