Multi-piece stacked sealing system and method of using same

Abstract

Subsea wells have a variety of proprietary well head configurations that require sophisticated locking and sealing profiles that allow the well bore to be sealed off and the production of hydrocarbons to be safely controlled. A universal tubing hanger and lockdown assembly uses a sealing apparatus to annularly seal the well bore. When compressed, a multi-piece stacked sealing system employs rigid and elastic members to seal the well bore annulus in both the top-down and bottom-up directions. Top-down pressure containment is needed for appropriate well system testing and bottom-up pressure containment is necessary to control the internal pressure of the well.

1 . A system ( 10 ) for sealing an annular space between well bore tubulars, said system comprising:
 a plurality of rigid rings ( 20 ) having a tapered upper surface and a tapered lower surface and arranged and designed to be stacked around an inner tubular ( 82 ), said plurality of rigid rings each having an outside diameter smaller than an inside diameter of an outer tubular ( 118 );   a plurality of elastic rings ( 40 ,  44 ,  46 ) having a tapered upper surface and a tapered lower surface and arranged and designed to be stacked between said plurality of said rigid rings such that said tapered upper and lower surfaces of said rigid rings compliment said tapered upper and lower surfaces of said elastic rings, said plurality of elastic rings each having an outside diameter smaller than an inside diameter of said outer tubular;   an upper support ring ( 22 ) disposed above said plurality of rigid rings and having one ( 44 ) of said plurality of elastic rings interposed therebetween, said upper support ring having a tapered lower surface to compliment said tapered upper surface of said one of said plurality of elastic rings and having an outside diameter smaller than an inside diameter of said outer tubular, said upper support ring arranged and designed to be disposed around said inner tubular;   a lower support ring ( 24 ) disposed below said plurality of rigid rings and having another ( 46 ) of said plurality of elastic rings interposed therebetween, said lower support ring having a tapered upper surface to compliment said tapered lower surface of said another of said plurality of elastic rings and having an outside diameter smaller than an inside diameter of said outer tubular, said lower support ring arranged and designed to be disposed around said inner tubular;   an upper spring ( 60 ) disposed in an upper recessed groove ( 64 ) in an upper surface ( 52 ) of said one of said plurality of elastic rings, said upper recessed groove ( 64 ) forming a upper outer lip ( 56 ) within said one of said plurality of elastic rings, said upper spring arranged and designed to transfer axial force acting upon said upper support ring to said upper outer lip; and   a lower spring ( 62 ) disposed in a lower recessed groove ( 66 ) in an lower surface ( 54 ) of said another of said plurality of elastic rings, said lower recessed groove ( 66 ) forming a lower outer lip ( 57 ) within said another of said plurality of elastic rings, said lower spring arranged and designed to transfer axial force acting upon said lower support ring to said lower outer lip.   
     
     
         2 . The system of  claim 1  wherein,
 said upper support ring carries within an inner surface ( 32 ) thereof a seal arranged and designed to seal between said upper support ring and said inner tubular, and 
 said lower support ring carries within an inner surface ( 34 ) thereof a seal arranged and designed to seal between said lower support ring and said inner tubular. 
 
     
     
         3 . The system of  claim 1  wherein,
 said inner tubular is a tubing hanger ( 82 ) and said outer tubular is production casing ( 118 ). 
 
     
     
         4 . The system of  claim 1  wherein,
 said plurality of elastic rings are at least in part composed of a thermoplastic elastomer. 
 
     
     
         5 . The system of  claim 4  wherein,
 said thermoplastic elastomer is at least in part composed of a polyester. 
 
     
     
         6 . The system of  claim 1  wherein,
 said system is arranged and designed to be carried by a tubing hanger assembly ( 80 ). 
 
     
     
         7 . A method of sealing an annular space between well bore tubulars, said method comprising the steps of:
 carrying a sealing system ( 10 ) on an inner tubular ( 82 ), said sealing system having a plurality of rigid rings ( 20 ) tapered on an upper surface and a lower surface and stacked around said inner tubular, said plurality of rigid rings each having an outside diameter smaller than an inside diameter of an outer tubular ( 118 ), said sealing system further having a plurality of elastic rings ( 40 ,  44 ,  46 ) tapered on an upper surface and a lower surface and stacked between said plurality of said tapered rigid rings such that said upper and lower surfaces of said rigid rings compliment said upper and lower surfaces of said elastic rings, said plurality of elastic rings each having an outside diameter smaller than an inside diameter of said outer tubular, said sealing system further having an upper support ring ( 22 ) disposed above said plurality of rigid rings with one ( 44 ) of said plurality of elastic rings interposed therebetween, said upper support ring having a tapered lower surface to compliment said upper surface of said one of said plurality of elastic rings and having an outside diameter smaller than an inside diameter of said outer tubular, said upper support ring disposed around said inner tubular, said sealing system further having a lower support ring ( 24 ) disposed below said plurality of rigid rings with another ( 46 ) of said plurality of elastic rings interposed therebetween, said lower support ring having a tapered upper surface to compliment said lower surface of said another of said plurality of elastic rings and having an outside diameter smaller than an inside diameter of said outer tubular, said lower support ring arranged and designed to be disposed around said inner tubular, said sealing system further having an upper spring ( 60 ) disposed in an upper recessed groove ( 64 ) in an upper surface ( 52 ) of said one of said plurality of elastic rings, said upper recessed groove ( 64 ) forming an upper outer lip ( 56 ) within said one of said plurality of elastic rings, said upper spring arranged and designed to transfer axial force upon said upper support ring to said upper outer lip, and said sealing system further having a lower spring ( 62 ) disposed in a lower recessed groove ( 66 ) in an lower surface ( 54 ) of said another of said plurality of elastic rings, said lower recessed groove ( 66 ) forming an lower outer lip ( 57 ) within said another of said plurality of elastic rings, said lower spring arranged and designed to transfer axial force upon said lower support ring to said lower outer lip;   positioning said sealing system carried by said inner tubular within an outer tubular at a position for sealing an annular space between said outer tubular and said inner tubular using said sealing system; and   applying an axial force on said sealing system such that said upper support ring, said plurality of rigid rings, and said lower support ring are moved closer together, thereby compressing and deforming said plurality of elastic rings into sealing contact with said outer tubular.   
     
     
         8 . The method of  claim 7  wherein,
 said upper support ring carries a seal arranged and designed to seal between said upper support ring and said inner tubular, and 
 said lower support ring carries a seal arranged and designed to seal between said lower support ring and said inner tubular. 
 
     
     
         9 . The method of  claim 7  wherein,
 said axial force is produced by hydraulic fluid acting on said sealing system. 
 
     
     
         10 . The method of  claim 7  wherein,
 said inner tubular is a tubing hanger ( 82 ) and said outer tubular is production casing ( 118 ). 
 
     
     
         11 . The method of  claim 7  wherein,
 said plurality of elastic rings are at least in part composed of a thermoplastic elastomer. 
 
     
     
         12 . The method of  claim 11  wherein,
 said thermoplastic elastomer is at least in part composed of a polyester.