CIRCULATION SUB
A circulation sub tool includes a tool body with a bore extending therethrough, a sleeve movably disposed within the bore and having a sleeve bore extending therethrough, a collet disposed within the sleeve bore, and an activation dart configured to fit within the sleeve bore. The activation dart includes a dart body, a seal disposed on an outer surface of the dart body, and a channel recessed into the outer surface of the dart body.
1 . A circulation sub tool comprising:
a tool body with a bore extending therethrough;
a sleeve movably disposed within the bore and having a sleeve bore extending therethrough;
a collet disposed within the sleeve bore; and
an activation dart configured to fit within the sleeve bore and comprising:
a dart body;
a seal disposed on an outer surface of the dart body; and
a channel recessed into the outer surface of the dart body.
2 . The circulation sub tool of claim 1 , further comprising:
a dart catcher body coupled to the tool body and comprising a dart catcher bore extending therethrough; and
a cage disposed within the dart catcher body.
3 . The circulation sub tool of claim 2 , wherein the cage comprises openings that permit fluid to pass through the circulation sub tool when the activation dart is positioned in the cage.
4 . The circulation sub tool of claim 2 , wherein the cage has a length long enough to hold the activation dart, a second activation dart, and two deactivation darts.
5 . The circulation sub tool of claim 1 , further comprising a spring that biases the sleeve in a first position.
6 . The circulation sub tool of claim 1 , further comprising:
a port formed through a wall of the tool body; and
a sleeve port formed through a wall of the sleeve.
7 . The circulation sub tool of claim 6 , wherein when the sleeve is in a sleeve open position, the port formed through the wall of the tool body and the sleeve port formed through the wall of the sleeve are aligned.
8 . The circulation sub tool of claim 6 , wherein when the sleeve is in a sleeve closed position, the port formed through the wall of the tool body and the sleeve port formed through the wall of the sleeve are not aligned.
9 . The circulation sub tool of claim 6 , further comprising a deactivation dart comprising:
a dart body; and
a seal disposed on an outer surface of the dart body,
wherein, when the activation dart is seated in the collet, the deactivation dart has a length that positions a portion of the dart body to block the sleeve port when the deactivation dart is resting on the activation dart.
10 . The circulation sub tool of claim 1 , wherein the collet comprises a finger having a tab disposed on a distal end of the finger.
11 . The circulation sub tool of claim 10 , wherein:
the tab includes an angled face that contacts an angled face of the activation dart when the activation dart is seated in the collet; and
the angle of the angled faces tends to move the finger radially outward when a deactivation dart is landed on the activation dart.
12 . The circulation sub tool of claim 10 , wherein the tab extends into a channel formed into a surface of the activation dart when the activation dart is seated in the collet.
13 . The circulation sub tool of claim 1 , wherein the channel comprises:
a first face that is frustoconical in shape; and
a second face that is perpendicular to a central axis of the dart body.
14 . The circulation sub tool of claim 1 , wherein the activation dart comprises a bore that extends through the dart body.
15 . The circulation sub tool of claim 14 , wherein the activation dart comprises a nozzle that is disposed within the bore that extends through the dart body.
16 . The circulation sub tool of claim 15 , wherein the bore that extends through the dart body has a first portion with a first diameter and a second portion with a second diameter.
17 . The circulation sub tool of claim 16 , wherein the nozzle is disposed in the second portion.
18 . The circulation sub tool of claim 15 , wherein the nozzle comprises a beveled opening.
19 . The circulation sub tool of claim 1 , wherein:
the tool body comprises a guide pin that extends into a slot of the sleeve; and
the guide pin prevents rotational movement between the sleeve and the tool body.
20 . The circulation sub tool of claim 1 , wherein the channel includes a first face that tends to push fingers of the collet open when the activation dart moves in a downhole direction and a second face that prevents the activation dart from moving uphole.