Helical groove for a tubular connection

Abstract

A tubular connection and methods of manufacturing a box member. The tubular connection includes a box member that includes an internal thread and a pin member that includes an external thread. The external thread is adapted to threadedly engage the internal thread. A substantially helical groove is formed on an outer surface of the box member. The method of manufacturing the box member includes selecting an outer diameter for a box member that causes the tool joint to have a greater than a selected bending strength ratio. A helical groove is formed on the outer diameter of the box member such that the helical groove reduces the bending strength ratio to be about the selected bending strength ratio. An internal thread is formed on an internal surface of the box member. Another method of manufacturing the box member includes forming an internal thread on an internal surface of a cylinder and forming a substantially helical groove on an outer surface of the cylinder. The substantially helical groove is positioned substantially in-lead with the internal thread.

1 . A tubular connection comprising: 
 a box member comprising an internal thread;    a pin member comprising an external thread, the external thread adapted to threadedly engage the internal thread; and    a substantially helical groove formed on an outer surface of the box member.    
   
   
       2 . The tubular connection of  claim 1 , wherein the substantially helical groove is positioned substantially in-lead with the internal thread.  
   
   
       3 . The tubular connection of  claim 1 , wherein the box member further comprises a first seal surface and the pin member further comprises a second seal surface, wherein the first and second seal surfaces are adapted to form a seal after radial plastic expansion of the tubular connection.  
   
   
       4 . The tubular connection of  claim 1 , wherein the internal thread and external thread comprise substantially dovetail-shaped threads.  
   
   
       5 . The tubular connection of  claim 1 , wherein the at least one substantially helical groove has a cross section selected from the group consisting of a rectangular cross section, a trapezoidal cross section, a V-shaped cross section, a parabolic cross section, a U-shaped cross section, or a semi-circle cross section.  
   
   
       6 . The tubular connection of  claim 1 , wherein the at least one substantially helical groove has a cross section that varies along an axial length of the box member.  
   
   
       7 . The tubular connection of  claim 1 , wherein the internal thread and the external thread comprise wedge threads.  
   
   
       8 . The tubular connection of  claim 7 , wherein a width of the at least one substantially helical groove varies at a rate substantially equal to a varying of a width of crests of the internal thread.  
   
   
       9 . The tubular connection of  claim 7 , wherein the internal thread and external thread are substantially dovetail-shaped threads.  
   
   
       10 . A tubular connection comprising: 
 a box member comprising an internal thread, a first seal surface, and a second seal surface;    a pin member comprising an external thread, a third seal surface, and a fourth seal surface, the external thread adapted to threadedly engage the internal thread and the first and third seal surfaces are adapted to form a seal against an external pressure and the second and fourth seal surfaces are adapted to form a seal against an internal pressure upon engagement thereof; and    a substantially helical groove formed on an outer surface of the box member,    wherein the substantially helical groove is positioned substantially in-lead with the internal thread.    
   
   
       11 . The tubular connection of  claim 10 , further comprising: 
 a groove formed on an internal surface of the box member proximate the second seal surface, wherein the groove is adapted to receive a sealing ring.    
   
   
       12 . The tubular connection of  claim 10 , further comprising: 
 a groove formed on an external surface of the pin member proximate the third seal surface, wherein the groove is adapted to receive a sealing ring.    
   
   
       13 . The tubular connection of  claim 10 , wherein the internal thread and the external thread comprise substantially dovetail-shaped threads.  
   
   
       14 . The tubular connection of  claim 10 , wherein the at least one substantially helical groove has a cross section selected from the group consisting of a rectangular cross section, a trapezoidal cross section, a V-shaped cross section, a parabolic cross section, a U-shaped cross section, or a semi-circle cross section.  
   
   
       15 . The tubular connection of  claim 13 , wherein the at least one substantially helical groove has a cross section that varies along an axial length of the box member.  
   
   
       16 . The tubular connection of  claim 10 , wherein the internal thread and external thread comprise wedge threads.  
   
   
       17 . The tubular connection of  claim 16 , wherein a width of the at least one substantially helical groove varies at a rate substantially equal to a varying of a width of crests of the internal thread.  
   
   
       18 . The tubular connection of  claim 16 , wherein the internal thread and external thread are substantially dovetail-shaped threads.  
   
   
       19 . A method of manufacturing a box member of a tool joint, the method comprising: 
 selecting an outer diameter for a box member, wherein the outer diameter causes the tool joint to have a greater than a selected bending strength ratio;    forming a helical groove on the outer diameter of the box member, wherein the helical groove reduces the bending strength ratio to be about the selected bending strength ratio; and    forming an internal thread on an internal surface of the box member.    
   
   
       20 . The method of  claim 19 , wherein the helical groove is positioned substantially in-lead with the internal thread.  
   
   
       21 . A method of modifying a box member comprising an internal thread, the method comprising: 
 forming a substantially helical groove on an outer surface of the box member,    wherein the substantially helical groove is positioned substantially in-lead with the internal thread.    
   
   
       22 . A method of manufacturing a box member, the method comprising: 
 forming an internal thread on an internal surface of a cylinder; and    forming a substantially helical groove on an outer surface of the cylinder,    wherein the substantially helical groove is positioned substantially in-lead with the internal thread.