Subsea Well Intervention Systems and Methods

Abstract

A system for performing an intervention on a subsea wellhead, the system including a production tree having a central axis, a first end, a second end, and a first flow bore extending axially from the first end to the second end. The production tree includes a master valve disposed along the first flow bore, a swab valve disposed along the first flow bore between the master valve and the first end, and a shearing device disposed along the first flow bore between the master valve and the second end. The second end of the production tree comprises a connector configured to releasably couple to the subsea wellhead, and the shearing device is configured to shear a component extending through the first flow bore.

1 - 18 . (canceled) 
     
     
         19 . A system for performing an operation on a subsea well, the system comprising:
 a production tree having an upper end, a lower end, and a first flow bore extending vertically from the upper end to the lower end, wherein the production tree includes a first valve disposed along the first flow bore, a second valve disposed along the first flow bore between the first valve and the upper end, and a shearing device disposed along the first flow bore between the first valve and the lower end;   wherein the lower end of the production tree comprises a connector configured to releasably couple to the subsea well;   wherein the shearing device is configured to shear a component extending through the landing string and the first flow bore;   a landing string comprising an elongate conduit and a running tool coupled to a lower end of the elongate conduit, wherein the running tool is configured to releasably and directly attach to the upper end of the production tree.   
     
     
         20 . The system of  claim 19 , wherein the upper end of the production tree comprises a receptacle, and wherein the running tool is configured to be received and seated within the receptacle. 
     
     
         21 . The system of  claim 20 , wherein the running tool is configured to be releasably locked in the receptacle. 
     
     
         22 . The system of  claim 19 , wherein the running tool is configured to sealingly engage the upper end of the production tree. 
     
     
         23 . The system of  claim 19 , further comprising a valve disposed at the lower end of the elongate conduit. 
     
     
         24 . The system of  claim 19 , wherein the production tree includes a second flow bore extending horizontally from the first flow bore between the first valve and the second valve, and wherein the production tree includes a third valve disposed along the second flow bore. 
     
     
         25 . A method for performing an operation on a subsea well disposed below a sea surface, the method comprising:
 (a) isolating the subsea well with a subsea production tree disposed at an upper end of the subsea well, wherein the production tree has an upper end, a lower end, a vertical flow bore extending from the upper end to the lower end;   (b) lowering a landing string subsea from a vessel disposed at the sea surface, wherein the landing string includes a conduit, a running tool coupled to a lower end of the conduit, and a retainer valve disposed at the lower end of the conduit;   (c) directly attaching and securing the running tool to the upper end of the production tree;   (d) allowing fluid communication between the subsea well and the conduit through the vertical flow bore after (c).   
     
     
         26 . The method of  claim 25 , wherein (c) comprises:
 (c1) receiving the running tool into a receptacle at the upper end of the production tree;   (c2) seating the running tool in the receptacle; and   (c3) locking the running tool in the receptacle after (c2).   
     
     
         27 . The method of  claim 26 , wherein (b) further comprises forming a seal between the running tool and the production tree. 
     
     
         28 . The method of  claim 25 , wherein (b) comprises lowering the landing string from the vessel through open water to the production tree. 
     
     
         29 . The method of  claim 25 , wherein (a) comprises closing a first valve or a second valve in the vertical flow bore. 
     
     
         30 . The method of  claim 29 , wherein (d) comprises opening the first valve and the second valve. 
     
     
         31 . The method of  claim 25 , further comprising removing a cap from the upper end of the production tree before (c). 
     
     
         32 . The method of  claim 25 , further comprising:
 (e) lowering an intervention member through the conduit, the running tool, and the vertical flow bore of the production tree into the subsea well after (d).   
     
     
         33 . The method of  claim 32 , further comprising:
 (f) closing a shearing device positioned along the vertical flow bore below the first valve and the second valve; and   (g) shearing the intervention member disposed in the vertical bore.   
     
     
         34 . The method of  claim 33 , further comprising:
 (h) lifting an upper portion of the sheared intervention member into the landing string after (g);   (i) isolating the well with the production tree after (h);   (j) closing the retainer valve; and   (k) decoupling the landing string from the upper end of the production tree after (j).   
     
     
         35 . A method for performing an operation on a subsea well disposed below a sea surface, the method comprising:
 (a) isolating the subsea well with a subsea production tree disposed at an upper end of the subsea well, wherein the production tree has an upper end, a lower end, and a vertical flow bore extending from the upper end to the lower end;   (b) lowering a landing string from a vessel disposed at the sea surface through open water to the production tree, wherein the landing string includes a conduit, a running tool coupled to a lower end of the conduit, and a retainer valve disposed at the lower end of the conduit;   (c) releasably coupling the running tool to the upper end of the production tree;   (d) allowing fluid communication between the subsea well and the conduit through the vertical flow bore after (c); and   (e) lowering an intervention member through the conduit, the running tool, and the vertical flow bore of the production tree into the subsea well after (d).   
     
     
         36 . The method of  claim 35 , wherein (c) comprises directly attaching and securing the running tool to the upper end of the production tree. 
     
     
         37 . The method of  claim 36 , wherein (c) comprises:
 (c1) receiving the running tool into a receptacle at the upper end of the production tree;   (c2) seating the running tool in the receptacle; and   (c3) locking the running tool in the receptacle after (c2).   
     
     
         38 . The method of  claim 37 , wherein (c) further comprises forming a seal between the running tool and the production tree, wherein the seal is configured to prevent the flow of fluids between the running tool and the production tree. 
     
     
         39 . The method of  claim 35 , wherein (a) comprises closing a first valve or a second valve in the vertical flow bore; and
 wherein (d) comprises opening the first valve and the second valve.