Subsea completion system and method of using same

Abstract

The present invention is directed to various embodiments of a subsea production system. In one illustrative embodiment, a subsea completion system includes a tubing string, a Christmas tree defining a bottom opening adapted to have the tubing string inserted therein, and means for latching the tubing string to prevent movement relative to the Christmas tree. A method includes coupling a tubing string with a Christmas tree above water and landing the Christmas tree on a subsea wellhead.

1 . A subsea completion system, comprising: 
 a tubing string;    a Christmas tree defining a bottom opening adapted to have the tubing string inserted therein; and    means for latching the tubing string to prevent movement relative to the Christmas tree.    
   
   
       2 . A subsea completion system, according to  claim 1 , wherein the means for latching the tubing string in the subsea completion system comprises a tubing hanger assembly adapted to be operatively coupled with the Christmas tree.  
   
   
       3 . A subsea completion system, according to  claim 2 , wherein the Christmas tree defines a bore including a sealing surface and a groove profile and the tubing hanger assembly comprises: 
 a body including an upper end received in the bore of the Christmas tree and a lower end threadedly connected to the tubing string;    a seal disposed on the upper end engaged with the sealing surface of the Christmas tree bore for sealing between the Christmas tree and the body;    a lock ring disposed about the body;    an anti-backoff member threadedly engaged with the body; and    a lock mandrel slidably disposed about the body and resting on the anti-backoff member, the lock mandrel being engageable with the lock ring to expand the lock ring and engage the groove profile of the Christmas tree.    
   
   
       4 . A subsea completion system, according to  claim 3 , wherein the anti-backoff member comprises an anti-backoff nut.  
   
   
       5 . A subsea completion system, according to  claim 3 , wherein the Christmas tree bore includes a first sealing surface and a second sealing surface and the tubing hanger assembly comprises a metal-to-metal seal engaged with the first sealing surface and an elastomeric seal engaged with the second sealing surface.  
   
   
       6 . A subsea completion system, according to  claim 1 , wherein the Christmas tree comprises an annulus valve disposed on the side of the Christmas tree or in a separate wing block of the Christmas tree.  
   
   
       7 . A subsea completion system, according to  claim 1 , wherein the tubing string is latched above water.  
   
   
       8 . A subsea completion system, according to  claim 1 , further comprising a tubing hanger, wherein the tubing string is latched to the Christmas tree via the tubing hanger.  
   
   
       9 . A subsea completion system, according to  claim 1 , further comprising a tubing hanger and a tubing head, wherein the tubing string is latched to the Christmas tree via the tubing hanger and the tubing head.  
   
   
       10 . A subsea completion system, according to  claim 9 , wherein the tubing hanger comprises a latch.  
   
   
       11 . A subsea completion system, according to  claim 9 , wherein the tubing head comprises a latch.  
   
   
       12 . A subsea completion system, according to  claim 1 , further comprising a tubing hanger, wherein the tubing string is adapted to be latched to a well head via the tubing hanger.  
   
   
       13 . A subsea completion system, according to  claim 1 , wherein the means for latching comprises one of a hydraulically actuated connector, a threaded connector, a threaded retainer nut, and a shrink-fit coupling.  
   
   
       14 . A subsea completion system, according to  claim 13 , wherein the shrink-fit coupling comprises: 
 a pin attached to one of the tubing string and the Christmas tree; and    a box defining a fluid flow path and attached to the other of the tubing string and the Christmas tree, the box being operatively engageable with the pin,    wherein the box is disengaged from the pin when a pressurized fluid is transmitted through the fluid flow path and the box is engaged with the pin when a pressurized fluid is absent from the fluid flow path.    
   
   
       15 . A subsea completion system, according to  claim 14 , further comprising a sealing element for inhibiting or preventing fluid flow between the box and the pin.  
   
   
       16 . A system adapted to be coupled to a subsea wellhead, comprising: 
 a tubing hanger adapted to be positioned in the wellhead, the tubing hanger defining a flow opening extending therethrough; and    a Christmas tree operatively coupled to the tubing hanger above water.    
   
   
       17 . A system, according to  claim 16 , further comprising a tubing string attached to the tubing hanger and defining a flow opening therethrough, such that the flow opening of the tubing string and the flow opening of the tubing hanger are in fluid communication.  
   
   
       18 . A system, according to  claim 16 , wherein the Christmas tree is operatively coupled to the tubing hanger via a tubing head.  
   
   
       19 . A method, comprising: 
 coupling a tubing string with a Christmas tree above water; and    landing the Christmas tree on a subsea wellhead.    
   
   
       20 . A method, according to  claim 19 , wherein coupling the tubing string with the Christmas tree comprises installing a tubing hanger on an uppermost joint of the tubing string and locking the tubing hanger to the Christmas tree.  
   
   
       21 . A method, according to  claim 20 , wherein locking the tubing hanger to the Christmas tree comprises expanding a lock ring of the tubing hanger.  
   
   
       22 . A method, according to  claim 21 , wherein expanding the lock ring of the tubing hanger comprises engaging a lock mandrel of the tubing hanger with the lock ring.  
   
   
       23 . A method, according to  claim 20 , further comprising lowering the tubing hanger, with the tubing string attached, to a support structure of a rig or vessel.  
   
   
       24 . A method, according to  claim 23 , further comprising landing the Christmas tree on tree supports disposed on the support structure.  
   
   
       25 . A method, according to  claim 24 , further comprising manipulating the tree supports to mate the Christmas tree and the tubing hanger.  
   
   
       26 . A method, according to  claim 19 , further comprising guiding the Christmas tree to the subsea wellhead using the tubing string.  
   
   
       27 . A method, according to  claim 26 , further comprising installing a stabbing guide over the subsea wellhead before guiding the Christmas tree to the subsea wellhead.  
   
   
       28 . A method, according to  claim 27 , wherein installing the stabbing guide comprises installing the stabbing guide with a remotely operated vehicle.  
   
   
       29 . A method, according to  claim 19 , further comprising running the Christmas tree, the tubing hanger, and the tubing string open-water to a well extending from the subsea wellhead.  
   
   
       30 . A method, according to  claim 29 , wherein running the Christmas tree, the tubing hanger, and the tubing string further comprises running the Christmas tree, the tubing hanger, and the tubing string without a blow-out preventer.  
   
   
       31 . A method, according to  claim 19 , further comprising removing a stabbing guide from the subsea wellhead before landing the Christmas tree on the subsea wellhead.  
   
   
       32 . A method, according to  claim 31 , wherein removing the stabbing guide comprises removing the stabbing guide with a remotely operated vehicle.  
   
   
       33 . A method, according to  claim 19 , wherein coupling the tubing string with the Christmas tree comprises installing a tubing hanger on an uppermost joint of the tubing string, locking the tubing hanger in a tubing head, and attaching the tubing head to the Christmas tree.  
   
   
       34 . A method, comprising: 
 coupling a tubing string with a tubing hanger above water;    landing the tubing hanger on a subsea wellhead; and    landing a Christmas tree on the subsea wellhead.    
   
   
       35 . A method, according to  claim 34 , further comprising latching the tubing hanger to the Christmas tree.  
   
   
       36 . A method, according to  claim 34 , further comprising latching the tubing hanger to the wellhead.  
   
   
       37 . A method, according to  claim 34 , wherein landing the tubing hanger on the subsea wellhead further comprises landing the tubing hanger on the subsea wellhead via a tubing head and latching the tubing hanger to the tubing head.  
   
   
       38 . A subsea Christmas tree defining a lower bore adapted to mate with a tubing string, such that the tubing string is latchable in the Christmas tree.  
   
   
       39 . A subsea Christmas tree, according to  claim 38 , wherein the lower bore is adapted to mate with the tubing string via one of a tubing hanger, a hydraulically actuated connector, a threaded connector, a threaded retainer nut, and a shrink fit coupling.