Pressure-compensated flow shut-off sleeve for wellhead and subsea well assembly including same

Abstract

A flow shut-off sleeve assembly adapted to be coupled to a subsea wellhead housing disposed within a conductor housing, which opens and closes at least one flow port in the conductor housing to annular fluid flow, is provided. The flow shut-off sleeve assembly includes an internal annular flow shut-off sleeve disposed around an exterior portion of the subsea wellhead housing and an external annular flow shut-off sleeve disposed around an exterior portion of the internal annular flow shut-off sleeve. The external annular flow shut-off sleeve is movable axially relative to the internal annular flow shut-off sleeve between an open position wherein the at least one flow port is open to annular fluid flow and a closed position, wherein the at least one flow port is closed to annular fluid flow. A subsea well assembly is also provided, which includes the flow shut-off sleeve assembly.

1 . A flow shut-off sleeve assembly adapted to be coupled to a subsea wellhead housing disposed within a conductor housing, which opens and closes at least one flow port in the conductor housing to annular fluid flow, the assembly comprising: 
 an internal annular flow shut-off sleeve disposed around an exterior portion of the subsea wellhead housing; and    an external annular flow shut-off sleeve disposed around an exterior portion of the internal annular flow shut-off sleeve, the external annular flow shut-off sleeve movable axially relative to the internal annular flow shut-off sleeve between an open position and a closed position.    
   
   
       2 . The flow shut-off sleeve assembly according to  claim 1 , wherein the internal annular flow shut-off sleeve comprises at least one first opening disposed therein and the external annular flow shut-off sleeve comprises at least one second opening disposed therein.  
   
   
       3 . The flow shut-off sleeve assembly according to  claim 2 , wherein the at least one first opening of the internal annular flow shut-off sleeve is substantially aligned with the at least one second opening of the external annular flow shut-off sleeve in the open position, and wherein the at least one first opening of the internal annular flow shut-off sleeve is substantially nonaligned with the at least one second opening of the external annular flow shut-off sleeve in the closed position.  
   
   
       4 . The flow shut-off sleeve assembly according to  claim 2 , wherein the external annular flow shut-off sleeve is capable of being secured in a substantially permanently open position, wherein the at least one first opening of the internal annular flow shut-off sleeve is substantially aligned with the at least one second opening of the external annular flow shut-off sleeve.  
   
   
       5 . The flow shut-off sleeve assembly according to  claim 4 , wherein the external annular flow shut-off sleeve is secured to the internal annular flow shut-off sleeve by at least one shear screw.  
   
   
       6 . The flow shut-off sleeve assembly according to  claim 1 , further comprising a pair of seals disposed between the internal annular flow shut-off sleeve and the external annular flow shut-off sleeve, wherein one of the pair of seals is disposed above the at least one first opening and the other of the pair of seals is disposed below the at least one first opening.  
   
   
       7 . The flow shut-off sleeve assembly according to  claim 6 , wherein the pair of seals comprises a pair of O-rings.  
   
   
       8 . The flow shut-off sleeve assembly according to  claim 1 , further comprising a shearable attachment, which secures the external annular flow shut-off sleeve to the internal annular flow shut-off sleeve in a temporary open position.  
   
   
       9 . The flow shut-off sleeve assembly according to  claim 1 , further comprising an actuator means adapted to be coupled to a running tool and adapted to engage the external annular flow shut-off sleeve to cause it to move axially between the open position and the closed position.  
   
   
       10 . The flow shut-off sleeve assembly according to  claim 9 , wherein the actuator means comprises an actuator sleeve having an ear which is engaged by a skirt of the running tool and an actuator rod coupled to the actuator sleeve, which engages the external annular flow shut-off sleeve.  
   
   
       11 . A subsea well assembly comprising: 
 a subsea wellhead housing coupled to a string of casing extending through a string of conductor pipe, the conductor pipe coupled to a conductor housing, the conductor housing having a sidewall including at least one flow port and a support profile, the support profile supporting the subsea wellhead housing and the string of casing;    an internal annular flow shut-off sleeve disposed around an exterior portion of the subsea wellhead housing; and    an external annular flow shut-off sleeve disposed around an exterior portion of the internal annular flow shut-off sleeve, the external annular flow shut-off sleeve movable axially relative to the internal annular flow shut-off sleeve and the conductor pipe sidewall between an open position, wherein the at least one flow port is open to annular fluid flow, and a closed position, wherein the at least one flow port is closed to annular fluid flow.    
   
   
       12 . The subsea well assembly according to  claim 11 , wherein the internal annular flow shut-off sleeve comprises at least one first opening disposed therein and the external annular flow shut-off sleeve comprises at least one second opening disposed therein.  
   
   
       13 . The subsea well assembly according to  claim 12 , wherein the at least one first opening of the internal annular flow shut-off sleeve is substantially aligned with the at least one second opening of the external annular flow shut-off sleeve in the open position, and wherein the at least one first opening of the internal annular flow shut-off sleeve is substantially nonaligned with the at least one second opening of the external annular flow shut-off sleeve in the closed position.  
   
   
       14 . The subsea well assembly according to  claim 12 , wherein the external annular flow shut-off sleeve is capable of being secured in a substantially permanently open position, wherein the at least one first opening of the internal annular flow shut-off sleeve is substantially aligned with the at least one second opening of the external annular flow shut-off sleeve.  
   
   
       15 . The subsea well assembly according to  claim 14 , wherein the external annular flow shut-off sleeve is secured to the internal annular flow shut-off sleeve by at least one shear screw.  
   
   
       16 . The subsea well assembly according to  claim 11 , further comprising a pair of seals disposed between the internal annular flow shut-off sleeve and the external annular flow shut-off sleeve, wherein the pair of seals is disposed above and below the at least one first and second openings on a same diameter of the internal annular flow shut-off sleeve and wherein the external annular flow shut-off sleeve is adapted to slide axially over the pair of seals to close off flow through the at least one first and second openings.  
   
   
       17 . The subsea well assembly according to  claim 16 , wherein the pair of seals comprises a pair of O-rings disposed on the same diameter of the internal annular flow shut-off sleeve so as to make the pair of O-rings pressure balanced.  
   
   
       18 . The subsea well assembly according to  claim 11 , further comprising a shearable attachment, which secures the external annular flow shut-off sleeve to the internal annular flow shut-off sleeve in a temporary open position.  
   
   
       19 . The subsea well assembly according to  claim 11 , further comprising an actuator means adapted to be coupled to a running tool and adapted to engage the external annular flow shut-off sleeve to cause it to move axially between the open position and the closed position.  
   
   
       20 . The subsea well assembly according to  claim 19 , wherein the actuator means comprises an actuator sleeve having an ear which is engaged by a skirt of the running tool and an actuator rod coupled to the actuator sleeve, which engages the external annular flow shut-off sleeve.