Expansion apparatus having resistive medium

Abstract

An apparatus for expanding a portion of a tubular within a wellbore. The expansion assembly first comprises an expander tool. The expander tool is preferably a rotary expander tool which is lowered into the wellbore at the lower end of a working string. In one aspect, the rotary expander tool defines a tubular body having recesses, with each recess containing a compliant roller. The expansion assembly further comprises a chamber having a resistive medium therein. In one arrangement, the medium is a clean oil loaded into the chamber before being run into the wellbore. The fluid chamber is sized and configured to sealingly receive an elongated lower portion of the body of the expander tool. As the body of the expander tool travels into the fluid chamber, it encounters resistance from the fluid loaded therein. The fluid serves as a resistant force to the downward movement of the drill string and the expander tool during the expansion process, thereby preventing any rapid springing of the pipe string above it.

1 . An apparatus for expanding a tubular in a wellbore, the apparatus being disposed on a working string, the apparatus comprising: 
 an expander tool, the expander tool having an elongated tubular body;    a chamber for receiving a portion of the elongated tubular body when the expander tool is lowered during expansion operations; and    a resistive medium within the chamber for providing resistance against the body of the expander tool as the body enters the chamber.    
     
     
         2 . The apparatus of  claim 1 , wherein 
 the chamber comprises an outer wall having a side surface; and    the resistive medium is disposed within the outer wall.    
     
     
         3 . The apparatus of  claim 2 , wherein: 
 said chamber further comprises an inner wall;    said inner wall and said outer wall are connected by a connecting surface portion of said outer wall; and    said resistive medium is disposed between the inner wall and the outer wall.    
     
     
         4 . The apparatus of  claim 3 , wherein said resistive medium is a fluid.  
     
     
         5 . The apparatus of  claim 4 , wherein said resistive medium is oil.  
     
     
         6 . The apparatus of  claim 2 , wherein said resistive medium is a powerful spring.  
     
     
         7 . The apparatus of  claim 4 , wherein said chamber further comprises: 
 at least one valve disposed proximate to the connecting surface, each valve being designed to prevent fluid from entering the chamber, but to open so as to permit fluid to exit the chamber once pressure within the chamber reaches a designated level.    
     
     
         8 . The apparatus of  claim 7 , wherein the at least one valve is sized to permit the resistive fluid medium to slowly bleed from the chamber after the valve has been opened and as the body of the expander tool advances into the chamber.  
     
     
         9 . The apparatus of  claim 8 , wherein the at least one valve includes a diaphragm.  
     
     
         10 . The apparatus of  claim 8 , wherein the at least one valve defines a one-way valve.  
     
     
         11 . An apparatus for expanding a tubular in a wellbore, the apparatus being disposed on a working string, the apparatus comprising: 
 an expander tool, the expander tool having an elongated tubular body;    a chamber for receiving a portion of the elongated tubular body when said expander tool is lowered during expansion operations, the chamber comprising an inner wall and an outer wall; and    a resistive medium disposed between the inner wall and the outer wall of the chamber for providing resistance against the body of the expander tool as the body enters the chamber.    
     
     
         12 . The apparatus of  claim 11 , wherein said resistive medium is a fluid.  
     
     
         13 . The apparatus of  claim 12 , wherein said resistive medium is oil.  
     
     
         14 . The apparatus of  claim 11 , wherein said resistive medium is a powerful spring.  
     
     
         15 . The apparatus of  claim 13 , wherein said chamber further comprises: 
 a connecting surface connecting the inner wall and the outer wall; and    at least one valve disposed proximate to the connecting surface each valve being designed to prevent fluid from entering the chamber, but to open so as to permit fluid to exit the chamber once pressure within the chamber reaches a designated level.    
     
     
         16 . The apparatus of  claim 15 , wherein the at least one valve comprises an opening that is sized to permit the resistive fluid medium to slowly bleed from the chamber after the valve has been opened and as the body of the expander tool advances into the chamber.  
     
     
         17 . The apparatus of  claim 16 , wherein the at least one valve defines at least two valves, the at least two valves being opened in response to different pressure levels in order to incrementally throttle advancement of the body into the chamber.  
     
     
         18 . The apparatus of  claim 16 , wherein the at least one valve includes a pressure-sensitive diaphragm.  
     
     
         19 . The apparatus of  claim 11 , wherein the length of the chamber defines and controls the length of tubular that gets expanded.