Ball valve capping stack

Abstract

A capping stack for use with a subsea well includes a ball valve disposed along a first flowline that is axially aligned with a main flowbore of a manifold body so that a tubing string can be passed through the ball valve into the well and whereby the ball valve can be activated to both close the flowline and sever the tubing string as desired. The main flowbore of the manifold body is defined along a primary axis and the capping stack includes second and third flowlines that each intersect the primary axis at an angle greater than zero and that each include a choke mechanism and a pair of spaced apart ball valves disposed along the flowline.

What is claimed is: 
     
         1 . A capping stack for use with a subsea well, the capping stack comprising:
 a manifold body having a main flowbore defined along a primary axis, a first flowbore in fluid communication with the main flowbore and axially aligned with the main flowbore, and a second flowbore in fluid communication with the main flowbore and intersecting the primary axis at an angle greater than zero;   a first flowline in fluid communication with the first flowbore and affixed to the manifold body so as to be axially aligned with the primary axis, the first flowline having a proximal end adjacent the manifold body and a distal end;   a second flowline in fluid communication with the second flowbore, the second flowline having a proximal end adjacent the manifold body and a distal end;   a ball valve disposed along the first flowline between the proximal and distal ends of the first flowline;   a valve disposed along the second flowline between the proximal and distal ends of the second flowline; and   a choke mechanism disposed along the second flowline between the valve and the distal end of the second flowline,   wherein the ball valve is movable between a first position and a second position, said first position allows tubing to be passed through the flowline and manifold body along the primary axis and said second position blocks passage of tubing through said ball valve.   
     
     
         2 . The capping stack of  claim 1 , wherein the valve disposed along the second flowline is a ball valve. 
     
     
         3 . The capping stack of  claim 1 , wherein said manifold body has a third flowbore in fluid communication with the main flowbore and intersecting the primary axis at an angle greater than zero, and wherein the valve disposed along the second flowline is a ball valve, said capping stack further comprising a third flowline in fluid communication with the third flowbore, the third flowline having a proximal end adjacent the manifold body and a distal end; a ball valve disposed along the third flowline between the proximal and distal ends of the third flowline; and a choke mechanism disposed along the third flowline between the ball valve and the distal end of the third flowline. 
     
     
         4 . The capping stack of  claim 3 , further a connector having a bore defined therein along a connector axis, said connector affixed to the manifold body so that the connector bore and main flowbore are axially aligned to permit tubing to be passed therethrough. 
     
     
         5 . The capping stack of  claim 4 , wherein said connector comprises a stab connector assembly. 
     
     
         6 . The capping stack of  claim 1 , further comprising: a frame at least partially enclosing the manifold body and the ball valve along the first flowline. 
     
     
         7 . The capping stack of  claim 6 , wherein said frame comprises a deck from which an upper portion of each flowline extents, and a support structure mounted on said deck and supporting the upper portion of the second flowline. 
     
     
         8 . The capping stack of  claim 3 , further comprising an additional ball valve disposed along each flowline and spaced apart from the other ball valve along the flowline. 
     
     
         9 . The capping stack of  claim 10 , wherein each flowline comprises a first portion at the proximal end of the flowline and a second portion at the distal end of the flowline, wherein the second portions of the first, second and third flowlines are substantially parallel. 
     
     
         10 . The capping stack of  claim 11 , wherein one ball valve along a flowline is located along the first portion of the flowline and one ball valve along the flowing is located along the second portion of the flowline. 
     
     
         11 . A method for well intervention comprising:
 attaching a capping stack to a subsea wellhead, BOP or other subsea mandrel;   passing well intervention equipment through the capping stack along a flowline of the capping stack; and   actuating a first ball valve disposed along the flowline in order to sever a tubing string on which the well intervention equipment is supported.   
     
     
         12 . The method of  claim 9 , further comprising: withdrawing the tubing remaining in the flowline upstream of the first ball valve; and actuating a second ball valve disposed along the flowline upstream of the first ball valve. 
     
     
         13 . The method of  claim 11 , wherein actuating the ball valve comprises driving the ball valve from an open position to a closed position. 
     
     
         14 . The method of  claim 13 , further comprising, releasing flow from the capping stack through multiple flowlines. 
     
     
         15 . The method of  claim 11 , further comprising aligning a central flowline of the capping stack with the central flow passage of a wellhead and passing the well intervention equipment through the central flowline and central flow passage into a wellbore. 
     
     
         16 . The method of  claim 15 , further comprising, performing well intervention operations within the wellbore. 
     
     
         17 . The method of  claim 11 , further comprising, attaching well intervention equipment to a tubing string and utilizing the tubing string to deploy the well intervention equipment into the wellbore by passing the tubing string along a flowline of the capping stack. 
     
     
         18 . A capping stack for use with a subsea well, the capping stack comprising:
 a manifold body having a main flowbore defined along a primary axis, a first flowbore in fluid communication with the main flowbore and axially aligned with the main flowbore, and a second and third flowbores in fluid communication with the main flowbore, each of the second and third flowbores intersecting the primary axis at an angle greater than zero;   a first flowline in fluid communication with the first flowbore and affixed to the manifold body so as to be axially aligned with the primary axis, the first flowline having a proximal end adjacent the manifold body and a distal end;   a second flowline in fluid communication with the second flowbore, the second flowline having a proximal end adjacent the manifold body and a distal end;   a third flowline in fluid communication with the third flowbore, the third flowline having a proximal end adjacent the manifold body and a distal end;   a ball valve disposed along the first flowline between the proximal and distal ends of the first flowline and movable between a first position and a second position;   a ball valve disposed along the second flowline between the proximal and distal ends of the second flowline and movable between a first position and a second position;   a ball valve disposed along the third flowline between the proximal and distal ends of the second flowline and movable between a first position and a second position;   a choke mechanism disposed along the second flowline between the valve and the distal end of the second flowline;   a choke mechanism disposed along the third flowline between the valve and the distal end of the third flowline,   wherein the first position of the ball valve along the first flowline allows tubing to be passed through the first flowline and manifold body along the primary axis.   
     
     
         19 . The capping stack of  claim 18 , further comprising an additional ball valve disposed along each flowline and spaced apart from the other ball valve along the flowline, wherein each flowline comprises a first portion at the proximal end of the flowline and a second portion at the distal end of the flowline, wherein the second portions of the first, second and third flowlines are substantially parallel, and wherein one ball valve along a flowline is located along the first portion of the flowline and one ball valve along the flowing is located along the second portion of the flowline. 
     
     
         20 . The capping stack of  claim 19 , further comprising: a frame at least partially enclosing the manifold body and the ball valve along the first portion of each flowline.