Method of expanding a tubular member in a wellbore

Abstract

The present invention provides methods for expanding a tubular with the aid of a compressive force. A tubular, such as a string of casing, is run into a wellbore on a working string, e.g., drill pipe. A carrying mechanism such as a collet is used to releasably attach the first tubular to the working string during run-in. The tubular is then expanded into frictional engagement with another tubular therearound within the wellbore. During the expansion process, a compressive force is applied to the portion of the tubular being expanded. In one aspect of the invention, a hydraulic ram is positioned above the string of casing and is activated by the injection of fluid under pressure in order to apply the compressive force to the expandable tubular. In another aspect of the invention, the portion of casing or other expandable tubular to be expanded is pre-stressed, such as to impart a barrel shape, in order to bias the tubular to more easily buckle outwardly during expansion.

1 . A method for expanding a first tubular into a second tubular in a wellbore, comprising the steps of: 
 positioning the first tubular within a wellbore;    running the second tubular to a selected depth within the wellbore such that at least a portion of the second tubular overlaps with the first tubular;    applying a compressive force to at least a portion of the second tubular; and    expanding a portion of the second tubular which is in compression so that the outer surface of the expanded portion of the second tubular is in frictional contact with the inner surface of the first tubular.    
     
     
         2 . The method for expanding a first tubular into a second tubular of  claim 1 , wherein the step of running the second tubular to a selected depth within the wellbore is accomplished by connecting the second tubular to a carrying mechanism on a working string.  
     
     
         3 . The method for expanding a first tubular into a second tubular of  claim 2 , wherein the step of applying a compressive force to at least a portion of the second tubular is accomplished by positioning a compressive force apparatus on top of the second tubular, and activating the compressive force apparatus so as to impart a downward force from the top of the second tubular.  
     
     
         4 . The method for expanding a first tubular into a second tubular of  claim 3 , wherein 
 said compressive force apparatus is a hydraulically actuated ram; and    said step of activating the compressive force apparatus so as to impart a downward force on the top of the second tubular is done by injecting fluid into an annular region within said hydraulically actuated ram.    
     
     
         5 . The method for expanding a first tubular into a second tubular of  claim 3 , wherein the first tubular and the second tubular each define a string of casing.  
     
     
         6 . The method for expanding a first tubular into a second tubular of  claim 5 , wherein 
 said carrying mechanism is a collet; and    said step of expanding a portion of the second tubular is accomplished by actuating a rotary expander tool having a plurality of rollers, said rotary expander tool being activated by hydraulic pressure.    
     
     
         7 . The method for expanding a first tubular into a second tubular of  claim 6 , further comprising the step of placing a swivel between said collet and said rotary expander tool such that rotation of said rotary expander tool does not interfere with the connection between said collet and the second tubular.  
     
     
         8 . The method for expanding a first tubular into a second tubular of  claim 6 , further comprising the steps of: 
 releasing said collet from said second tubular after expansion of the second tubular has begun; and    raising said expander tool within the wellbore so as to further expand the second tubular along a desired length.    
     
     
         9 . The method for expanding a first tubular into a second tubular of  claim 3 , further comprising the step of biasing at least a portion of the second tubular to be expanded before said step of running the second tubular to a selected depth within the wellbore, so as to bias said portion of the second tubular to buckle outwardly upon said step of expanding a portion of the second tubular.  
     
     
         10 . The method for expanding a first tubular into a second tubular of  claim 9 , wherein the step of biasing at least a portion of the second tubular to be expanded is accomplished by pre-stressing the portion of the second tubular to be expanded outwardly.  
     
     
         11 . A method for expanding a first tubular into a second tubular in a wellbore, the first tubular and the second tubular each having a top portion and a bottom portion, comprising the steps of: 
 positioning the first tubular within a wellbore;    connecting the second tubular to a working string by a releasable carrying mechanism;    connecting a rotary expander tool to said working string above said carrying mechanism;    connecting a swivel to said working string between said carrying mechanism and said rotary expander tool;    connecting a compressive force apparatus to said working string above said rotary expander tool, such that said compressive force apparatus is disposed on the top of the second tubular;    running the second tubular to a selected depth within the wellbore on said working string such that the top portion of the second tubular overlaps with the bottom portion of the first tubular;    activating said compressive force apparatus to apply a compressive force to the top portion of the second tubular between the top of the second tubular and the point of connection of the second tubular with the releasable carrying mechanism; and    activating said rotary expander tool so as to expand at least a portion of the top portion of the second tubular into frictional engagement with the inner surface of the first tubular.    
     
     
         12 . The method for expanding a first tubular into a second tubular of  claim 11 , wherein the first tubular and the second tubular each define a string of casing.  
     
     
         13 . The method for expanding a first tubular into a second tubular of  claim 12 , wherein said compressive force apparatus is a hydraulically actuated ram comprising: 
 a tubular mandrel having a top end, a bottom end, and a bore therein, said hollow bore being in fluid communication with said working string;    an outer body having a top end, a bottom end, and an inner surface therebetween,;    a through-opening within said mandrel;    an annular region between said mandrel and said inner surface of said body for receiving fluid from said through-opening in said mandrel, the annular region being configured such that the cross-sectional area of fluid above said through-opening is greater than the cross-sectional area of fluid below said through-opening;    an upper seal in said annular region, said upper seal being disposed between said mandrel and said inner surface of said body above said through-opening; and    a lower seal in said annular region, said lower seal being disposed between said mandrel and said inner surface of said body below said through-opening, thereby creating a fluidly sealed annular region around said through-opening.    
     
     
         14 . The method for expanding a first tubular into a second tubular of  claim 13 , wherein 
 the top end of the mandrel is threadedly connected to the working string; and    the bottom end of the mandrel is in fluid communication with the expander tool.    
     
     
         15 . The method for expanding a first tubular into a second tubular of  claim 14 , wherein said step of activating said compressive force apparatus and said step of activating said rotary expander tool are accomplished by injecting hydraulic fluid under pressure through said working string and into said fluidly sealed annular region.  
     
     
         16 . The method for expanding a first tubular into a second tubular of  claim 15 , wherein said carrying mechanism is a collet.  
     
     
         17 . The method for expanding a first tubular into a second tubular of  claim 16 , further comprising the steps of: 
 releasing said collet from said second tubular after expansion of the second tubular has begun; and    raising said rotary expander tool within the wellbore so as to expand the second tubular along a desired length.    
     
     
         18 . The method for expanding a first tubular into a second tubular of  claim 17 , further comprising the step of biasing at least a portion of the second tubular to be expanded before said step of running the second tubular to a selected depth within the wellbore, so as to bias said portion of the second tubular to buckle outwardly upon said step of activating said rotary expander tool.  
     
     
         19 . The method for expanding a first tubular into a second tubular of  claim 18 , wherein the step of biasing at least a portion of the second tubular to be expanded is accomplished by pre-stressing the portion of the second tubular to be expanded outwardly.