Abstract: A hydraulic disconnect comprises: a downhole housing, an uphole housing, an inner mandrel, a piston, and a lock. The inner mandrel has a latch to restrict the downhole housing from relative downhole movement. The inner mandrel is connected for transmission of torque to the downhole housing. A piston is within the inner mandrel and has a latched position, and an unlatched position. The piston has a valve seat. The lock maintains the piston in the latched position, the lock being adapted to unlock in use upon receipt by the valve seat of a disconnect valve member and a predetermined hydraulic pressure. The uphole housing has a stop for restricting the downhole housing from relative uphole movement. The inner mandrel is threaded to the uphole housing and relative rotation between the uphole and the downhole housing tightens the downhole housing between the latch and the uphole housing.

Abstract: A hydraulic disconnect is disclosed comprising: a downhole housing; an uphole housing; an inner mandrel at least partially disposed telescopically within the downhole housing, the inner mandrel having a latch extendable in a radially outward direction to latch against an inner shoulder of the downhole housing to restrict the downhole housing from relative downhole movement, the inner mandrel being connected for transmission of torque to the downhole housing; a piston at least partially disposed telescopically within the inner mandrel and having a latched position in which an outer surface of the piston is radially inward of the latch to maintain latching against the inner shoulder, and an unlatched position in which a groove in the outer surface is radially inward of the latch to allow radial contraction of the latch into the groove for release of the inner shoulder, the piston having a valve seat; and a lock for maintaining the piston in the latched position, the lock being adapted to unlock in use upon rece