High degree of freedom riser tensioner system

Abstract

A riser tensioner system has a riser support device, an actuator, and a bearing assembly disposed between the riser support device and the actuator. The bearing assembly is configured to provide at least five degrees of freedom of movement of the riser support device relative to the actuator.

What is claimed is: 
     
         1 . A riser tensioner system ( 114 ), comprising:
 a riser support device ( 118 );   an actuator ( 120 ); and   a high degree of freedom (HDOF) bearing assembly ( 124 ) disposed between the riser support device ( 118 ) and the actuator ( 120 ), the HDOF bearing assembly ( 124 ) being configured to provide at least five degrees of freedom of movement of the riser support device ( 118 ) relative to the actuator ( 120 ).   
     
     
         2 . The riser tensioner system ( 114 ) of  claim 1 , wherein the HDOF bearing assembly ( 124 ) comprises at least two bearing stacks ( 132 ,  140 ). 
     
     
         3 . The riser tensioner system ( 114 ) of  claim 2 , wherein at least one of the two bearing stacks comprises a HDOF spherical bearing stack ( 132 ). 
     
     
         4 . The riser tensioner system ( 114 ) of  claim 3 , wherein the HDOF spherical bearing stack ( 132 ) allows a relative cocking motion. 
     
     
         5 . The riser tensioner system ( 114 ) of  claim 2 , wherein at least one of the two bearing stacks comprises a planar bearing stack ( 140 ). 
     
     
         6 . The riser tensioner system ( 114 ) of  claim 5 , wherein the planar bearing stack ( 140 ) allows a relative translational motion. 
     
     
         7 . The riser tensioner system ( 114 ) of  claim 2 , wherein the at least two bearing stacks ( 132 ,  140 ) comprise a HDOF spherical bearing stack ( 132 ) configured to allow a relative cocking motion and planar bearing stack ( 140 ) configured to allow a relative translational motion. 
     
     
         8 . An offshore hydrocarbon production system ( 100 ), comprising:
 a riser tensioner system ( 114 ), comprising:
 a riser support device ( 118 ); 
 an actuator ( 120 ); and 
 a high degree of freedom (HDOF) bearing assembly ( 124 ) disposed between the riser support device ( 118 ) and the actuator ( 120 ), the HDOF bearing assembly ( 124 ) being configured to provide at least five degrees of freedom of movement of the riser support device ( 118 ) relative to the actuator ( 120 ). 
   
     
     
         9 . The riser tensioner system ( 114 ) of  claim 8 , wherein the HDOF bearing assembly ( 124 ) comprises at least two bearing stacks ( 132 ,  140 ). 
     
     
         10 . The riser tensioner system ( 114 ) of  claim 9 , wherein at least one of the two bearing stacks comprises a HDOF spherical bearing stack ( 132 ). 
     
     
         11 . The riser tensioner system ( 114 ) of  claim 10 , wherein the HDOF spherical bearing stack ( 132 ) allows a relative cocking motion. 
     
     
         12 . The riser tensioner system ( 114 ) of  claim 9 , wherein at least one of the two bearing stacks comprises a planar bearing stack ( 140 ). 
     
     
         13 . The riser tensioner system ( 114 ) of  claim 12 , wherein the planar bearing stack ( 140 ) allows a relative translational motion. 
     
     
         14 . The riser tensioner system ( 114 ) of  claim 9 , wherein the at least two bearing stacks ( 132 ,  140 ) comprise a HDOF spherical bearing stack ( 132 ) configured to allow a relative cocking motion and planar bearing stack ( 140 ) configured to allow a relative translational motion. 
     
     
         15 . A method of providing six degrees of freedom of movement between a riser ( 108 ) of an offshore hydrocarbon production system ( 100 ) and a platform ( 102 ), comprising:
 disposing a high degree of freedom (HDOF) bearing assembly ( 124 ) between a riser ( 108 ) and an actuator ( 120 ), the HDOF bearing assembly ( 124 ) comprising at least two bearing stacks ( 132 ,  140 ).   
     
     
         16 . The method of  claim 15 , wherein at least one of the two bearing stacks comprises a HDOF spherical bearing stack ( 132 ). 
     
     
         17 . The method of  claim 16 , wherein the HDOF spherical bearing stack ( 132 ) allows a relative cocking motion. 
     
     
         18 . The method of  claim 15 , wherein at least one of the two bearing stacks comprises a planar bearing stack ( 140 ). 
     
     
         19 . The method of  claim 18 , wherein the planar bearing stack ( 140 ) allows a relative translational motion. 
     
     
         20 . The method of  claim 15 , wherein the at least two bearing stacks ( 132 ,  140 ) comprise a HDOF spherical bearing stack ( 132 ) configured to allow a relative cocking motion and planar bearing stack ( 140 ) configured to allow a relative translational motion.