Reamer tool positionable in a wellbore

Abstract

Described herein is a reamer tool ( 100 ) having a body ( 105 ) with bays ( 115 ) in which cutter arms ( 110 ) are mounted for deployment between a stowed position and a deployed position. A deployment mechanism is provided for deploying the cutter arms from their stowed position to their deployed position that maintains each cutter arm in a position that is substantially parallel to a longitudinal axis of the body ( 105 ) whilst in its stowed position and in its deployed position as well as during its deployment from its stowed position to its deployed position. A control module ( 300 ) is also described for controlling the deployment of the cutter arms ( 110 ). The control module ( 300 ) comprises a motor ( 310 ), a gearing mechanism ( 315 ) and a moveable element ( 320 ) that closes a port ( 385 ) in a first position and opens the port ( 385 ) in a second position. Fluid flow enters a chamber ( 340 ) behind a piston ( 170 ) through the port ( 385 ) to allow pressure to build up before actuating the piston ( 170 ) and thereby the deployment mechanism for the cutter arms ( 170 ).

1 . A reamer tool positionable downhole in a wellbore, said tool comprising:
 a substantially hollow body having a longitudinal axis and including an external wall having a first outer diameter; at least one arm bay formed in a portion of the external wall around the periphery of the body;   at least one expandable arm located in an associated arm bay and mounted for expansion between a retracted position within the body and an expanded position in which each expandable arm describes a second outer diameter which is greater than the first outer diameter; and   at least one expansion mechanism for expanding an associated expandable arm between the retracted and expanded positions; wherein each expansion mechanism comprises two elongate links pivotally connected to the associated expandable arm at one end position and to its associated arm bay at another end position, each expandable arm being pivotally mounted at the two end positions with respect to its associated arm bay so that each expandable arm is maintained substantially parallel to the longitudinal axis in both the retracted and expanded positions, and, during its expansion and retraction between the retracted and expanded positions.   
     
     
         2 . The reamer tool of  claim 1 , further comprising an actuation mechanism for activating the expansion mechanism, each expandable arm being pivotally connected at another end position to the actuation mechanism. 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . The reamer tool of  claim 1 , further comprising at least one return member for deactivating each expansion mechanism. 
     
     
         6 . The reamer tool of  claim 5 , wherein each return member comprises a spring biased against the action of the actuating mechanism. 
     
     
         7 . The reamer tool of  claim 1 , further comprising a shoulder block locatable in each arm bay to limit the expansion of the expandable arm. 
     
     
         8 . The reamer tool of  claim 1 , wherein the second outer diameter is up to 1.3 times the first outer diameter. 
     
     
         9 . The reamer tool of  claim 1 , wherein each expandable arm comprises a cutter arm. 
     
     
         10 . An expandable cutter arm for a reamer tool postionable downhole in a wellbore, the expandable cutter arm comprising at least a front cutting blade and a back cutting blade, each cutting blade comprising a plurality of cutting elements, one cutting element on each of the front cutting blade and the back cutting blade providing an attack point for the associated cutting blade. 
     
     
         11 . The expandable cutter arm of  claim 10 , further comprising a first side and a second side located either side of a plane, each side being spaced at respective predetermined distances from the plane so that the attack point for the front blade and the attack point for the back blade are equi-spaced from the plane. 
     
     
         12 . The expandable cutter arm of  claim 11 , wherein the predetermined distance for the first side is different to the predetermined distance for the second side. 
     
     
         13 . The expandable cutter arm of  claim 10 , wherein the cutting elements comprise polycrystalline diamond cutting element. 
     
     
         14 . A reamer tool postionable downhole in a wellbore, said tool having at least one expandable cutter arm comprising:
 at least a front cutting blade and a back cutting blade, each cutting blade comprising a plurality of cutting elements, one cutting element on each of the front cutting blade and the back cutting blade providing an attack point for the associated cutting blade; and   a first side and a second side located either side of a plane, each side being spaced at respective predetermined distances from the plane so that the attack point for the front blade and the attack point for the back blade are equi-spaced from the plane, and wherein the predetermined distance for the first side is different to the predetermined distance for the second side.   
     
     
         15 . A reamer tool positionable downhole in a wellbore, said tool having a longitudinal axis, the reamer tool comprising at least one expandable cutter arm, each expandable cutter arm having a plurality of cutting elements arranged to form at least a front cutting blade and a back cutting blade, one of the cutting elements on the front cutting blade and one of the cutting elements on the back cutting blade providing respective attack points for their associated cutting blades, wherein the attack point for the front cutting blade and the attack point for the back cutting blade are equi-spaced from a plane extending through the longitudinal axis. 
     
     
         16 . The reamer tool of  claim 15 , further comprising at least one expansion mechanism for expanding an associated expandable cutter arm between a retracted position and an expanded position, and an actuation mechanism for activating each expansion mechanism. 
     
     
         17 . The reamer tool of  claim 16 , wherein each expansion mechanism comprises at least two elongate links pivotally connected to the associated expandable cutter arm at one end position and to its associated arm bay at another end position, each expandable cutter arm are being pivotally mounted at the two positions with respect to its associated arm bay so that each expandable cutter arm is maintained substantially parallel to the longitudinal axis in both the retracted and expanded positions, and, during expansion and retraction between the retracted and expanded positions. 
     
     
         18 . The reamer tool of  claim 17 , wherein the expansion mechanism further comprises a third elongate link pivotally connected to each expandable cutter arm and to the actuation mechanism, each expandable cutter arm being pivotally connected at another end position to the actuation mechanism. 
     
     
         19 . The reamer tool of  claim 16 , wherein the actuation mechanism comprises a piston. 
     
     
         20 . The reamer tool of  claim 16 , further comprising at least one return member for deactivating each expansion mechanism. 
     
     
         21 . The reamer tool of  claim 15 , further comprising a shoulder block locatable in each arm bay to limit the expansion of the expandable cutter arm. 
     
     
         22 . The reamer tool of  claim 21 , wherein the expandable cutter arm has an opening range up to 1.3 times an outer diameter of the reamer tool, the shoulder block limiting the opening in accordance with its size. 
     
     
         23 - 33 . (canceled)