Pressure amplifiers for downhole drilling tools

Abstract

A drilling system includes a drill string having a BHA carrying a drill bit, a steering pad carried by the BHA and radially moveable relative to a longitudinal axis of the BHA and a pressure amplifier connected between the steering pad and a hydraulic fluid at a first pressure, the pressure amplifier comprising a piston axially moveable in response to application of the first hydraulic pressure to move the steering pad radially at a steering force.

What is claimed is: 
     
         1 . A steerable drilling tool, comprising:
 a steering pad radially moveable relative to a longitudinal tool axis; and   a pressure amplifier operationally connected to the steering pad to increase a hydraulic fluid pump pressure applied to the steering pad.   
     
     
         2 . The tool of  claim 1 , wherein the pressure amplifier comprises a piston configured to move along an axial path substantially parallel to the tool axis. 
     
     
         3 . The tool of  claim 1 , wherein the pressure amplifier is a differential pressure amplifier. 
     
     
         4 . The tool of  claim 1 , wherein the pressure amplifier is a multiple stage pressure amplifier. 
     
     
         5 . The tool of  claim 1 , wherein the pressure amplifier is configured to act on a fluid to radially move the steering pad. 
     
     
         6 . The tool of  claim 1 , wherein the pressure amplifier is configured to act on a shaft to radially move the steering pad. 
     
     
         7 . The tool of  claim 1 , wherein the tool comprises a first component pivotally connected to a second component carrying a drill bit, the first and the second component pivot relative to one another in response to radially extending the steering pad. 
     
     
         8 . The tool of  claim 7 , wherein the pressure amplifier comprises a piston configured to move along an axial path substantially parallel to the tool axis, and the piston is configured to act on a fluid to radially move the steering pad. 
     
     
         9 . The tool of  claim 7 , wherein the pressure amplifier comprises a piston configured to move along an axial path substantially parallel to the tool axis, and the piston is configured to act on a shaft to radially move the steering pad. 
     
     
         10 . A method, comprising:
 applying a first hydraulic pressure to a pressure amplifier operationally connected to a steering pad located in a bottom hole assembly (BHA) having a drill bit and disposed in a wellbore;   driving a piston of the pressure amplifier axially relative to a longitudinal axis of the BHA; and   moving the steering pad with a steering force radially away from the longitudinal axis of the BHA in response to driving the piston axially.   
     
     
         11 . The method of  claim 10 , wherein the pressure amplifier is a differential pressure amplifier. 
     
     
         12 . The method of  claim 10 , wherein the pressure amplifier is a multiple stage pressure amplifier. 
     
     
         13 . The method of  claim 10 , wherein the moving the steering pad comprises increasing a pressure of a charging fluid over the first hydraulic pressure in response to driving the piston axially, the piston operationally connected to the steering pad by the charging fluid. 
     
     
         14 . The method of  claim 10 , wherein the piston of the pressure amplifier is operationally connected to the steering pad by a shaft. 
     
     
         15 . The method of  claim 10 , further comprising applying the steering force via the pad to a wall of the wellbore. 
     
     
         16 . The method of  claim 10 , further comprising pivoting first component and a second component of the BHA relative to one another in response to radially extending the steering pad. 
     
     
         17 . A drilling system, comprising:
 a drill string having a bottom hole assembly (BHA) carrying a drill bit;   a steering pad carried by the BHA and radially moveable relative to a longitudinal axis of the BHA; and   a pressure amplifier connected between the steering pad and a hydraulic fluid at a first pressure, the pressure amplifier comprising a piston axially moveable in response to application of the first hydraulic pressure to move the steering pad radially at a steering force.   
     
     
         18 . The system of  claim 17 , wherein the pressure amplifier is one of a differential pressure amplifier and a multiple stage pressure amplifier. 
     
     
         19 . The system of  claim 17 , wherein the piston is configured to act on a fluid to radially move the steering pad. 
     
     
         20 . The system of  claim 17 , wherein the piston is configured to act on a shaft to radially move the steering pad.