Methods and apparatus for increasing the reach of coiled tubing

Abstract

The subject disclosure generally relates to the field of elongated structures such as coiled tubing and coiled tubing applications in hydrocarbon wells. More particularly, the subject disclosure relates to increasing the reach of coiled tubing by delaying the onset of buckling.

1 . A method of delaying the onset of buckling in an elongated structure having an outer surface traversing a tubular path having an inner surface, comprising:
 adapting at least one of the outer surface of the elongated structure and the inner surface of the tubular path to increase a coefficient of friction between the outer surface of the elongated structure and the inner surface of the tubular path in a first direction, while maintaining or decreasing a coefficient of friction between the outer surface of the elongated structure and the inner surface of the tubular path in a second direction; and   inserting said elongated structure into the tubular path.   
     
     
         2 . A method according to  claim 1 , wherein:
 said first direction is a lateral direction, and said second direction is an axial direction.   
     
     
         3 . A method according to  claim 1 , wherein:
 said adapting comprises providing said outer surface of the elongated structure with a plurality of longitudinal rails.   
     
     
         4 . A method according to  claim 3 , wherein:
 at least one of said plurality of longitudinal rails has a generally triangular cross-section.   
     
     
         5 . A method according to  claim 1 , wherein:
 said adapting comprises providing said inner surface of the tubular path with a plurality of longitudinal rails.   
     
     
         6 . A method according to  claim 5 , wherein:
 at least one of said plurality of longitudinal rails has a generally triangular cross-section.   
     
     
         7 . A method according to  claim 1 , wherein:
 said adapting comprises providing both said outer surface of the elongated structure and said inner surface of the tubular path with a plurality of longitudinal rails.   
     
     
         8 . A method according to  claim 1 , wherein:
 said plurality of longitudinal rails are integral with the outer surface of the pipe structure.   
     
     
         9 . A method according to  claim 1 , wherein:
 said plurality of longitudinal rails are integral with the inner surface of the tubular path.   
     
     
         10 . A method according to  claim 1 , wherein:
 said tubular path is a wellbore casing.   
     
     
         11 . A method according to  claim 1 , wherein:
 said elongated structure is a pipe formed from a coiled tubing.   
     
     
         12 . A method according to  claim 10 , wherein:
 said elongated structure is a pipe formed from a coiled tubing.   
     
     
         13 . A method of delaying the onset of buckling in an elongated structure having an outer surface traversing a tubular path having an inner surface, comprising:
 adapting the elongated structure to have an anisotropic bending stiffness; and   inserting said elongated structure into the tubular path.   
     
     
         14 . A method according to  claim 13 , wherein:
 at a first location said elongated structure has a cross-section with an outer surface defining a circle and an inner surface defining an oval.   
     
     
         15 . A method according to  claim 13 , wherein:
 at a first location said elongated structure has a cross-section with an outer surface defining an oval and an inner surface defining a circle.   
     
     
         16 . A method according to  claim 13 , wherein:
 at a first location said elongated structure has a cross-section with an outer surface defining a first circle and an inner surface defining a second circle, wherein said first circle is non-concentric with said second circle.   
     
     
         17 . A method according to  claim 13 , wherein:
 said elongated structure includes a helical seam weld.   
     
     
         18 . A method according to  claim 14 , wherein:
 said elongated structure includes a longitudinal seam weld.   
     
     
         19 . A method according to  claim 14 , wherein:
 said elongated structure has an orientation of anisotropic bending stiffness that varies along the length of the elongated structure.   
     
     
         20 . A method according to  claim 13 , wherein:
 said tubular path is a wellbore casing.   
     
     
         21 . A method according to  claim 20 , wherein:
 said elongated structure is a pipe formed from a coiled tubing.   
     
     
         22 . A method according to  claim 13 , wherein:
 said elongated structure is a pipe formed from a coiled tubing.   
     
     
         23 . An apparatus wound about a reel and for use in a tubular path, comprising:
 a hollow pipe wound about the reel to form a coiled tubing, said pipe when unwound from the reel having a length of at least 1000 feet, an outer diameter of between 0.75 inches and 5.0 inches, and adapted to have at least one of (i) an anisotropic bending stiffness, and (ii) an outer surface adapted to increase a coefficient of friction between the outer surface and an inner surface of the tubular path in a first direction while maintaining or decreasing a coefficient of friction between the outer surface of and the inner surface of the tubular path in a second direction.   
     
     
         24 . An apparatus according to  claim 23 , wherein:
 said hollow pipe has an anisotropic bending stiffness with an orientation that varies along the length of the pipe.   
     
     
         25 . An apparatus according to  claim 23 , wherein:
 said hollow pipe has an outer surface having a plurality of longitudinal rails.