Wellbore tool with indexing mechanism and method

Abstract

A wellbore tool, a wellbore fluid treatment string and a method with an indexing mechanism. The indexing mechanism can be shifted through one or more inactive positions before finally shifting into an active condition. The indexing mechanism is particularly useful with a plug that lands in a seat to impart an axially directed force on the mechanism before passing through the seat.

1 . A wellbore tool that is actuable through a plurality of positions comprising:
 a tubular housing including an upper end, a lower end, an axis extending between the ends and a wall defined between an inner surface and an outer surface;   a tool mechanism capable of being reconfigured from a first inactive position to an active position;   an indexing mechanism for reconfiguring the tool mechanism, the indexing mechanism including an indexing ring in the tubular housing, the indexing ring including an inner bore and being rotatably movable about the axis, and an inner sleeve positioned within the tubular housing and extending through the inner bore, the inner sleeve having an axial bore extending therethrough and a wall thickness, and a plurality of pawls forming a seat on the inner sleeve, each of the plurality of pawls being pivotally connected to the inner sleeve and having an inner facing surface open to and biased into the axial bore and a back side surface positioned for engagement with the indexing ring; and   an actuator for passing through the axial bore and contacting the inner facing surfaces to drive the plurality of pawls radially out into full meshing engagement with the indexing ring to thereby drive the indexing ring to rotate and to move the tool mechanism from the first inactive position toward the active position.   
     
     
         2 . The wellbore tool of  claim 1  wherein the indexing ring is rotatably moveable in one rotational direction only about the axis. 
     
     
         3 . The wellbore tool of  claim 1  wherein the indexing ring is a gear ring with an internally toothed profile and the plurality of pawls include at least one protrusion on the back side surface to mesh with the internally toothed profile. 
     
     
         4 . The wellbore tool of  claim 1  wherein the plurality of pawls are each pivotally connected to rotate about a fulcrum axis substantially parallel to the axis. 
     
     
         5 . The wellbore tool of  claim 1  wherein the sleeve is retained against rotating about the axis. 
     
     
         6 . The wellbore tool of  claim 1  wherein in the active position, the indexing ring is stopped from rotating. 
     
     
         7 . The wellbore tool of  claim 1  wherein in the active position, the plurality of pawls are stopped from rotation into full meshing engagement such that a sleeve shifting device cannot pass through the plurality of pawls. 
     
     
         8 . The wellbore tool of  claim 1  wherein the tool mechanism is the seat and in the active position, the seat forms a non-expandable ball seat. 
     
     
         9 . The wellbore tool of  claim 6  wherein the seat in the inactive position is expandable. 
     
     
         10 . A wellbore sliding sleeve sub comprising:
 a tubular housing including an upper end, a lower end, an axis extending through the upper end and the lower end and a wall defined between an inner surface and an outer surface;   a port through the wall of the tubular housing;   a sleeve in the tubular housing, the sleeve having an inner bore and being moveable from a closed position overlying the port to an open position exposing the port;   a ball seat on the sleeve configurable between an expandable form and non-expandable form, the ball seat including a plurality of pawls, each pawl having a front side surface exposed in the inner bore and a backside surface opposite the front side surface and each pawl being pivotally connected to the sleeve through a fulcrum having an axis of rotation substantially parallel to the axis such that the pawls are rotationally moveable between a constricted position protruding into the inner bore and an expanded position having an inner diameter greater than the constricted position;   an indexing mechanism for reconfiguring the ball seat from the inactive position to the active position, the indexing mechanism including a pawl protrusion on the back side surface of at least one pawl and an indexing ring with a plurality of teeth on its inner facing surface, the plurality of teeth forming at least one valley capable of meshing with the pawl protrusion, the indexing ring being rotatable relative to the sleeve and encircling the sleeve about the plurality of pawls, expansion of the plurality of pawls from the constricted position to the expanded position driving meshing of the pawl protrusion with the at least one valley and rotation of the indexing ring to accommodate the meshing; and   an actuator for passing through the inner bore and contacting the front side surfaces of the plurality of pawls to drive the pawls to the expanded position to force the pawl protrusion to mesh with the valley of the indexing ring and thereby to rotate the indexing ring relative to the sleeve to reconfigure the ball seat from the expandable form toward the non-expandable form.   
     
     
         11 . The wellbore sliding sleeve sub of  claim 10  wherein misalignment between the pawl protrusion and the valley drives rotation of the indexing ring when the pawl protrusion meshes with the valley. 
     
     
         12 . The wellbore sliding sleeve sub of  claim 10  wherein the indexing ring includes a number of valleys and the number of valleys defines a number of actuators that are passable through the plurality of pawls before the ball seat is moved to the non-expandable form. 
     
     
         13 . The wellbore sliding sleeve sub of  claim 10  wherein in the non-expandable form the indexing ring is stopped from rotation and the pawl protrusion is stopped from meshing. 
     
     
         14 . A wellbore fluid treatment string comprising a string and sliding sleeve sub according to  claim 11 , a first annular packer on the string uphole of the sliding sleeve sub and a second annular packer on the string downhole of the sliding sleeve sub, the first annular packer and the second annular packer being expandable to form an isolated wellbore segment therebetween. 
     
     
         15 . The wellbore fluid treatment string of  claim 14  further comprising a sleeve-shifting device to land on the ball seat after the ball seat is configured into the non-expandable form. 
     
     
         16 . A method for actuating a downhole tool to an active position, the method comprising: passing an actuator through a expandable ball seat in the downhole tool to permit incremental movement of an indexing ring about the ball seat until the indexing ring moves to a final position wherein the ball seat is held by the indexing ring against expanding and is capable of catching a sleeve shifting device. 
     
     
         17 . The method of  claim 16  wherein during passing the ball seat remains axially stationary in the downhole tool. 
     
     
         18 . The method of  claim 16  wherein passing includes driving a plurality of pawls that form the ball seat from a constricting position out into full meshing engagement with the indexing ring as the actuator passes over the plurality of pawls and biasing the plurality of pawls back into the constricting position when the actuator clears the plurality of pawls.