Controller for a Downhole Tool

Abstract

The controller comprises housing ( 2 ) within which located is an inner mandrel ( 4 ), which is biased in an upward direction by spring ( 16 ). Balls ( 10 ) in ducts ( 8 ) are locking the inner mandrel to housing ( 2 ). At a lower end of mandrel ( 4 ) are a plurality of ports ( 18 ) which may be aligned with a set of outer ports ( 22 ). When ports ( 18 ) are to be aligned with ports ( 22 ), the drill string is rotated, generating a centrifugal force which forces balls ( 10 ) radially along ducts ( 8 ), thereby unlocking inner mandrel from outer housing. Pressure is then applied to inner duct ( 7 ), creating a pressure difference across choke ( 6 ). Under sufficient pressure, the force created is sufficient to overcome the resistive force created by spring ( 16 ), and thus the inner mandrel translates axially to bring ports ( 18 ) in alignment with ports ( 22 ), through which some or all of the drilling fluid may flow, bypassing the rest of the drill string.

1 .- 32 . (canceled) 
     
     
         33 . A controller for switching between functional modes of a downhole tool, the controller comprising:
 an outer housing;   an inner mandrel located within the outer housing, through which drilling fluid may pass; and   a switching device adapted for switching between a plurality of functional modes by translating the inner mandrel within the outer housing;   wherein the outer housing comprises a ball which, when the downhole tool is rotating below a specific rate, protrudes from an inner surface of the housing, if unobstructed, and which is flush with the inner surface of the housing when the downhole tool is rotating at or above the specific rate;   wherein the inner mandrel further comprises a circumferential groove which receives the ball when rotation is below the specific rate so as to prevent translation of the inner mandrel.   
     
     
         34 . The controller of  claim 33 , wherein the ball is provided in an inclined port in the housing wall. 
     
     
         35 . The controller of  claim 33 , wherein the ball is spring loaded. 
     
     
         36 . The controller of  claim 33 , wherein the inner mandrel comprises one or more additional circumferential grooves which receive the ball. 
     
     
         37 . The controller of  claim 33 , wherein, if whilst the ball protrudes from the inner surface of the housing the pressure of the drilling fluid is under or exceeds a predetermined value, then the ball is prevented from becoming flush with the inner surface of the housing. 
     
     
         38 . The controller of  claim 33 , wherein the outer housing comprises a plurality of circumferentially aligned balls. 
     
     
         39 . The controller of  claim 38 , wherein the outer housing comprises one or more additional sets of circumferentially aligned balls. 
     
     
         40 . The controller of  claim 33 , wherein the switching device comprises an actuator operable to translate the inner mandrel within the housing to switch between the functional modes of the downhole tool. 
     
     
         41 . The controller of  claim 40 , wherein the actuator is electrical. 
     
     
         42 . The controller of  claim 33 , wherein the switching device comprises a choke to provide a pressure difference inside the inner mandrel, the inner mandrel being translatable within the housing in response to the pressure difference to switch between the functional modes of the downhole tool. 
     
     
         43 . The controller of  claim 42 , wherein a resistive force is provided to resist translation of the inner mandrel in response to the pressure difference. 
     
     
         44 . The controller of  claim 33 , wherein the functional modes include any of: acting as a conventional drill pipe, opening ports, moving of stabilizers, blades or sleeves, or a steering operation of a drill string or drill bit. 
     
     
         45 . The controller of  claim 44 , wherein the switching device comprises an actuator operable to translate the inner mandrel within the housing to switch between the functional modes of the downhole tool. 
     
     
         46 . The controller of  claim 44 , wherein the switching device comprises a choke to provide a pressure difference inside the inner mandrel, the inner mandrel being translatable within the housing in response to the pressure difference to switch between the functional modes of the downhole tool. 
     
     
         47 . The controller of  claim 33 , wherein the functional mode is determined from the axially translated displacement of the inner mandrel within the housing. 
     
     
         48 . The controller of  claim 47 , wherein the switching device comprises an actuator operable to translate the inner mandrel within the housing to switch between the functional modes of the downhole tool. 
     
     
         49 . The controller of  claim 47 , wherein the switching device comprises a choke to provide a pressure difference inside the inner mandrel, the inner mandrel being translatable within the housing in response to the pressure difference to switch between the functional modes of the downhole tool. 
     
     
         50 . A method of controlling a downhole tool using a controller, the controller comprising:
 an outer housing; and   an inner mandrel located within the outer housing, through which drilling fluid may pass;   wherein the outer housing comprises a ball which protrudes from an inner surface of the outer housing when the downhole tool is rotating below a specific rate, and the inner mandrel comprises a circumferential groove for receiving the ball;   the method comprising:
 rotating the downhole tool above a specific rate so that the ball is flush with the inner surface of the outer housing; and 
 translating the inner mandrel within the outer housing so as to switch between a plurality of functional modes. 
   
     
     
         51 . A controller for switching between functional modes of a downhole tool, the controller comprising:
 an outer housing;   an inner mandrel located within the outer housing, through which drilling fluid may pass;   a switching device adapted for switching between a plurality of functional modes by translating the inner mandrel within the outer housing; wherein the switching device comprises an actuator operable to translate the inner mandrel within the housing to switch between the functional modes of the downhole tool;   an electrically actuated locking means operable to lock the inner mandrel relative to the housing to prevent axial translation; and   a sensing device adapted to sense a plurality of input parameters; wherein the locking means releases the inner mandrel and the switching device switches from a first of the functional modes to a second of the functional modes when the sensing device senses a predetermined state of at least two of the input parameters.   
     
     
         52 . A method of controlling a downhole tool using a controller, the controller comprising:
 an outer housing; and   an inner mandrel located within the outer housing, through which drilling fluid may pass;   the method comprising:   locking the inner mandrel relative to the outer housing with an electrically actuated locking means to prevent axial translation;   sensing a plurality of input parameters; and   releasing the inner mandrel with the locking means and translating the inner mandrel within the outer housing an electrical actuator so as to switch between a plurality of functional modes when a predetermined state of at least two of the input parameters is sensed.