Riser

Abstract

A riser and a method for reducing the risk of failure of a riser system comprising a riser ( 100 ) arranged between an installation and a subsea well the riser ( 100 ) having a bore ( 116 ) for conveying fluids therebetween, the method comprising the step of providing at least one vortex shedding member ( 111 ) in said bore ( 116 ) of said riser ( 100 ) and flowing the fluid between the subsea well and the installation.

1 . A method for reducing the risk of failure of a riser system comprising a riser arranged between an installation and a subsea well, the riser having a bore for conveying fluids therebetween, the method comprising:
 providing at least one vortex shedding member in said bore of said riser; and   flowing the fluids between the subsea well and the installation.   
     
     
         2 . The method in accordance with  claim 1 , further comprising deploying said at least one vortex shedding member into the bore while the riser remains installed on said subsea well. 
     
     
         3 . The method in accordance with  claim 2 , wherein said at least one vortex shedding member comprises a coil biased against an inner surface of said riser. 
     
     
         4 . The method in accordance with  claim 3 , wherein the deploying the at least one vortex shedding member is carried out by unfurling the coil in the bore. 
     
     
         5 . The method in accordance with  claim 3 , wherein the deploying the at least one vortex shedding member is carried out by unfurling the coil in the bore with a constant pitch. 
     
     
         6 . The method in accordance with  claim 3 , further comprising dragging said coil through said bore to install the at least one vortex member in said bore. 
     
     
         7 . The method in accordance with  claim 6 , wherein the dragging said coil through said bore is carried out using a coiled tubing injector. 
     
     
         8 . The method in accordance with  claim 1 , wherein the at least one vortex shedding member comprises a tube filled with fluid, the method further comprising monitoring the fluid in the tube to assess integrity of the at least one vortex shedding member. 
     
     
         9 . A riser, comprising:
 a hollow tubular body having an inner surface defining a bore through which fluids may flow; and   an internal member arranged to follow a spiral path within the bore.   
     
     
         10 . The riser as claimed in  claim 9 , wherein the internal member forms a continuous spiral. 
     
     
         11 . The riser as claimed in  claim 9 , wherein the internal member is biased against or fixed to an inner surface of the riser. 
     
     
         12 . The riser as claimed in  claim 9 , wherein the internal member comprises a tube. 
     
     
         13 . The riser as claimed in  claim 9 , wherein said internal member comprises a plurality of fins projecting from the inner surface of the riser. 
     
     
         14 . The riser as claimed in  claim 9 , further comprising an inner liner having fins projecting from the inner liner into the bore of the riser. 
     
     
         15 . The riser as claimed in  claim 14 , wherein said inner liner is formed from a coiled strip having said fins arranged thereon. 
     
     
         16 . A method for installing a coiled internal member into a riser, the method comprising:
 dragging said coiled internal member through a bore on an end of a coiled tubing deployed along the riser with a coiled tubing injector.   
     
     
         17 . A riser, comprising:
 a hollow tubular body having an inner surface defining a bore through which fluids may flow; and   a vortex shedding member along a substantial portion thereof.