Devices, systems, and methods for selectively engaging downhole tool for wellbore operations

A dart for deployment into a passage defined by a wellbore flow conductor of a wellbore, the wellbore flow conductor including a stop, the dart comprising:

• a body having a leading end, a trailing end, a ball seat defined therein, and an inner flow path defined therein, the inner flow path having:
• one or more inlets, each inlet of the one or more inlets extending radially in the body and opening to a respective circumferential location at a lengthwise side of the body, the respective circumferential location being between the leading end and the trailing end;
• and
• an outlet at the trailing end of the body,
• the ball seat being positioned between the one or more inlets and the outlet;
• a ball releasably receivable in the ball seat, wherein when the ball is received in the ball seat, the ball blocks fluid communication between the one or more inlets and the outlet, and when the ball is released from the ball seat, fluid communication is permitted between the one or more inlets and the outlet;
• and
• an engagement mechanism slidably supported on an outer surface of the body, the engagement mechanism being movable relative to the body from a first position to a second position, wherein in the first position, the engagement mechanism blocks the one or more inlets at the respective circumferential locations, and in the second position, the one or more inlets are unblocked by the engagement mechanism, the dart being actuable to transition from an inactivated configuration to an activated configuration, wherein:
• in the inactivated configuration, the engagement mechanism is in the first position, the ball is received in the ball seat, there is an absence of flow communication between the passage and the one or more inlets by the occluding of the one or more inlets by the engagement mechanism, and there is an absence of co-operability of the dart with an opposing surface of the stop such that there is an absence of preventing downhole travel of the dart, relative to the wellbore flow conductor, by the stop;
• and
• in the activated configuration, the engagement mechanism is in the second position with effect that downhole travel of the dart, relative to the stop is prevented by co-operation between the engagement mechanism and the stop wherein an engageable surface of the engagement mechanism is disposed in abutting engagement with an opposing surface of the stop, and flow communication between the passage, downhole from the stop, and the one or more inlets at the respective circumferential locations, for releasing the ball from the ball seat, is established.