Positioning contact surface with a radial extension that decreases for a directional drilling assembly

Abstract

A downhole assembly for a directional drilling apparatus is provided. The downhole assembly includes at least one positioning element. The positioning element has a first radial extension when the downhole assembly is drilling a wellbore. When the downhole assembly inclination is greater than a predetermined amount, such as when the downhole assembly is horizontal, the positioning element has a second radial extension that is less than the first radial extension.

We claim: 
     
         1 . A downhole apparatus comprising:
 a housing configured and sized to fit within a wellbore, the housing including a drilling assembly at a bottom portion of the housing and having at least a first bend located above the drilling assembly;   at least one positioning element coupled to the housing, the at least one positioning element comprising:
 a blade wherein the blade comprises: 
 at least a radially inner portion and at least a removable radially outer portion coupled to the radially inner portion; and 
 wherein the blade has a first radial extension that includes the radially inner portion and the removable radially outer portion, 
 wherein the blade has a second radial extension that includes the radially inner portion when the removable radially outer portion is removed such that the second radial extension is less than the first radial extension. 
   
     
     
         2 . The downhole apparatus of  claim 1  wherein the at least one positioning element is coupled to the housing such that the first bend is located between the at least one positioning element and the drilling assembly. 
     
     
         3 . The downhole apparatus of  claim 1  wherein the blade is a metal and the removable radially outer portion is a wearable material. 
     
     
         4 . The downhole apparatus of  claim 3  wherein the wearable material comprises a material that is softer than a material comprising the radially inner portion. 
     
     
         5 . The downhole apparatus of  claim 4  wherein the wearable material selected from the group of material consisting of: a metal softer than the material of the first portion, a phenolic material softer than the material of the first portion, or a combination thereof. 
     
     
         6 . The downhole apparatus of  claim 1  wherein the removable radially outer portion comprises interstitial hard material. 
     
     
         7 . The downhole apparatus of  claim 1  wherein the removable radially outer portion is a dissolvable material. 
     
     
         8 . The downhole apparatus of  claim 7  wherein the dissolvable material is configured to dissolve based on a composition of a drilling fluid. 
     
     
         9 . The downhole apparatus of  claim 8  wherein the dissolvable material is a polymer material that dissolves in the presence of saltwater. 
     
     
         10 . A downhole apparatus comprising:
 a housing configured and sized to fit within a wellbore, the housing including a drilling assembly at a bottom portion of the housing and having at least a first bend located above the drilling assembly;   at least one positioning element coupled to the housing, the at least one positioning element comprising:
 a blade wherein the blade comprises: 
 at least a removable radially inner portion and at least a radially outer portion coupled to the removable radially inner portion; and 
 wherein the blade has a first radial extension that includes the removable radially inner portion and the radially outer portion, 
 wherein the blade has a second radial extension that includes the radially outer portion when the removable radially inner portion is removed such that the second radial extension is less than the first radial extension. 
   
     
     
         11 . The downhole apparatus of  claim 10  wherein the removable radially inner portion supports the radially outer portion until it is removed. 
     
     
         12 . The downhole apparatus of  claim 10  wherein the removable radially inner portion comprises a dissolvable material. 
     
     
         13 . The downhole apparatus of  claim 12  wherein the dissolvable material is a polymer. 
     
     
         14 . The downhole apparatus of  claim 13  wherein the polymer is configured to dissolve when salt is present in a drilling fluid. 
     
     
         15 . The downhole apparatus of  claim 10  wherein the radially outer portion comprises a hard metal. 
     
     
         16 . The downhole apparatus of  claim 10  wherein the radially inner removable portion comprises a piston operably coupled to a piston driver wherein the piston has an extended position and a retracted position such that the radially inner removable portion is removed when the piston is in the retracted position. 
     
     
         17 . The downhole apparatus of  claim 12  wherein the radially inner portion comprises a bladder and the dissolvable material comprises a seal for the bladder such that the bladder is filled with a fluid when the dissolvable material is not dissolved and the bladder is empty when the dissolvable material is dissolved. 
     
     
         18 . A downhole apparatus comprising:
 a housing configured and sized to fit within a wellbore, the housing including a drilling assembly at a bottom portion of the housing and having at least a first bend located above the drilling assembly;   at least one positioning element coupled to the housing, the at least one positioning element comprising:
 a movable first portion; and 
 a piston coupled to the first portion wherein the piston has an extended position and a retracted position, 
 wherein the movable first portion has a first radial extension when the piston is in the extended position and the movable first portion has a second radial extension less than the first radial extension when the piston is in the retracted position. 
   
     
     
         19 . The downhole apparatus of  claim 18  comprising a sensor to sense an inclination of the housing such that when the sensor detects that the inclination of the housing is greater than a predetermined orientation, the piston is moved from the extended position to the retracted position.