Piston converter for downhole drilling tool

Abstract

A steerable drilling tool in accordance to an embodiment includes a steering actuator having an axially moveable piston connected to a steering pad by a linkage to convert axial movement of the piston into a radial movement of the steering pad.

What is claimed is: 
     
         1 . A steerable drilling tool, comprising a steering actuator having an axially moveable piston connected to a steering pad by a linkage to convert axial movement of the piston into a radial movement of the steering pad. 
     
     
         2 . The tool of  claim 1 , wherein the steering pad comprises a rocker assembly. 
     
     
         3 . The tool of  claim 1 , comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         4 . The tool of  claim 1 , wherein the steering pad comprises a rocker assembly and further comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         5 . The tool of  claim 1 , further comprising a pair of steering components pivotally mounted to each other via a pivot joint and extending axially along a tool axis; and
 the steering actuator disposed with one of the pair of steering components such that axial movement of the piston moves the steering pad radially relative to the tool axis thereby pivoting the steering components relative to one another.   
     
     
         6 . The tool of  claim 5 , wherein the steering pad comprises a rocker assembly. 
     
     
         7 . The tool of  claim 5 , comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         8 . The tool of  claim 5 , wherein the steering pad comprises a rocker assembly and further comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         9 . A method, comprising:
 deploying a bottom hole assembly (BHA) on a drill string in a wellbore, the BHA comprising a drill bit and a steering actuator comprising an axially moveable piston connected to a steering pad by a linkage;   axially moving the piston in response to the application of a hydraulic pressure;   radially extending the steering pad in response to the axially moving the piston; and   steering the drill bit in response to radially extending the steering pad.   
     
     
         10 . The method of  claim 9 , wherein the steering pad comprises a rocker assembly. 
     
     
         11 . The method of  claim 9 , comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         12 . The method of  claim 9 , wherein the steering pad comprises a rocker assembly and further comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         13 . The method of  claim 9 , wherein the radially extending the steering pad comprises contacting the wellbore with the steering pad. 
     
     
         14 . The method of  claim 9 , wherein the radially extending the steering pad comprises pivoting a first and a second steering component relative to one another. 
     
     
         15 . The method of  claim 14 , comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         16 . A drilling system, comprising a bottom hole assembly (BHA) deployed in a wellbore on a drill string, the BHA comprising a drill bit and a steering actuator having an axially moveable piston connected to a steering pad by a linkage to convert axial movement of the piston into a radial movement of the steering pad. 
     
     
         17 . The system of  claim 16 , comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         18 . The system of  claim 16 , wherein the steering pad comprises a rocker assembly and further comprising a seal circumferentially encircling the axially moveable piston. 
     
     
         19 . The system of  claim 16 , wherein the BHA comprises a pair of steering components pivotally mounted to each other via a pivot joint and extending axially along a tool axis, whereby the steering components are pivoted relative to one another in response to radially extending the steering pad. 
     
     
         20 . The system of  claim 19 , comprising a seal circumferentially encircling the axially moveable piston.