Buoyancy element, riser assembly including a buoyancy element and a method of supporting a riser

Abstract

A buoyancy element, riser assembly including a buoyancy element and a method of supporting a riser are disclosed. The buoyancy element includes a body of at least partly flexible structure having a volume that is adjustable between an expanded and contracted position, and an entry port for fluid to be supplied to and/or removed from the body to thereby adjust the volume of the body.

1 . A buoyancy element for providing buoyancy to a flexible riser, comprising:
 a body of at least partly flexible structure having a volume that is adjustable between an expanded and contracted position, and   an entry port for fluid to be supplied to and/or removed from the body to thereby adjust the volume of the body in response to a signal from a control means external to the buoyancy element, and   a depth monitoring device for communicating depth or buoyancy level to the control means.   
     
     
         2 . A buoyancy element as claimed in  claim 1 , further comprising a conduit in fluid communication with the entry port for supplying fluid to and/or removing fluid from the body. 
     
     
         3 . A buoyancy element as claimed in  claim 1 , wherein the entry port is configured for fluid to be supplied to and removed from the body. 
     
     
         4 . A buoyancy element as claimed in  claim 2  further comprising a further tube in fluid communication with a further entry port to the body. 
     
     
         5 . A buoyancy element as claimed in  claim 1  further comprising one or more check valve configured to allow a maximum pressure of fluid within the body. 
     
     
         6 . A buoyancy element as claimed in  claim 1  wherein the body is an inflatable bladder. 
     
     
         7 . A buoyancy element as claimed in  claim 1 , wherein the body comprises a rigid support structure portion and a flexible portion. 
     
     
         8 . A buoyancy element as claimed in  claim 1 , further comprising a clamping element for clamping the buoyancy element to a flexible riser. 
     
     
         9 . A buoyancy element as claimed in  claim 8 , wherein the clamping element is attached to the rigid support structure portion of the body. 
     
     
         10 . (canceled) 
     
     
         11 . (canceled) 
     
     
         12 . A riser assembly for transporting fluids from a sub-sea location, comprising:
 a flexible pipe; and   one or more buoyancy element, comprising a body of at least partly flexible structure having a volume that is adjustable between an expanded and contracted position,   an entry port for fluid to be supplied to and/or removed from the body to thereby adjust the volume of the body in response to a signal from a control means external to the buoyancy element, and   a depth monitoring device for communicating depth or buoyancy level to the control means.   
     
     
         13 . A riser assembly as claimed in  claim 12 , further comprising a tethering element for tethering the riser assembly to a fixed structure. 
     
     
         14 . A riser assembly as claimed in  claim 12 , further comprising drag elements for decreasing the speed at which the flexible riser can move underwater. 
     
     
         15 . A riser assembly as claimed in  claim 12 , further comprising at least one buoyancy element of a substantially fixed buoyancy, not connected to a fluid supply/removal conduit. 
     
     
         16 . A method of supporting a riser, the method comprising the steps of:
 providing a riser comprising at least one segment of flexible pipe;   providing at least one buoyancy element for providing buoyancy to a portion of the riser, the buoyancy element having a body of at least partly flexible structure;   providing a control means external to the buoyancy element;   providing a depth monitoring device for communicating depth or buoyancy level to the control means; and   adjusting the volume of the body by supplying fluid to and/or removing fluid from the body in response to a signal from the control means.   
     
     
         17 - 19 . (canceled)