Riser support

Abstract

A riser system including: at least one riser for extending from infrastructure on a sea bed and each riser having a riser termination; an end support restrained above and relative to the sea bed and having attachment means to couple each riser termination for storage and decouple each riser termination for coupling to a floating vessel; and an intermediate support supporting an intermediate portion of the riser to define a catenary bend between the intermediate support and the riser termination device.

1 . A riser system including:
 at least one riser for extending from infrastructure on a sea bed and each riser having a riser termination;   an end support restrained above and relative to the sea bed and having attachment means to couple each riser termination for storage and decouple each riser termination for coupling to a floating vessel; and   an intermediate support supporting an intermediate portion of the riser to define a catenary bend between the intermediate support and the riser termination device.   
     
     
         2 . The riser system of  claim 1  wherein the intermediate support and end support are configured to support the catenary bend portion above and clear of the sea bed when the riser termination is supported by the end support. 
     
     
         3 . The riser system of  claim 1  or  2  wherein the intermediate support is formed by one or more floats. 
     
     
         4 . The riser system of  claim 1  or  2  wherein the relative depth and spacing of the intermediate support and end support are selected so that contact between the end support and the riser is prevented when the riser termination is coupled to a floating vessel. 
     
     
         5 . The riser system of  claim 1  or  2  including a plurality of risers and a respective intermediate support for each riser, each riser having a respective riser termination. 
     
     
         6 . The riser system of  5  wherein the riser terminations are cooperable with the end support; the end support having respective attachment means for each riser. 
     
     
         7 . The riser system of  claim 5  wherein the end support has multiple attachment means to support multiple risers. 
     
     
         8 . The riser system of  claim 5  wherein each attachment means includes lead-in features for leading the respective riser or a respective riser connection means into coupling alignment. 
     
     
         9 . A method of storing a riser termination for later coupling to a floating vessel, the method including the step of releasably coupling the riser termination to an end support to the end support being above and in a fixed position relative to the sea bed. 
     
     
         10 . The method of  claim 9  including supporting an intermediate portion of the riser using an intermediate support to define a catenary bend between the intermediate support and the riser termination. 
     
     
         11 . The riser system of  claim 10  wherein the relative depth and spacing of the intermediate support and end support are selected so that contact between the end support and the riser is prevented when the riser termination is coupled to a floating vessel. 
     
     
         12 . A method of installing a riser system including the steps of guiding a riser termination to couple with an end support restrained above and in a fixed position relative to a sea bed; extending the riser from the end support to an intermediate support for supporting the riser to define a catenary bend portion intermediate the intermediate support and the end support; and extending the riser from the intermediate support to a low connection point. 
     
     
         13 . The method of  claim 12  wherein the step of guiding the riser termination to couple with the end support includes extending a line between a top portion of the riser termination and a first vessel and suspending the riser termination in an inverted position, extending the riser such that the riser termination is lowered and is suspended from the line in an upright position, and manoeuvring the riser via the line to couple the riser termination to the end support. 
     
     
         14 . The method  claim 13  wherein the suspending of the riser termination is from a second vessel. 
     
     
         15 . The method of  claim 14  wherein the length of line is shorter than a sea bed depth so that the riser termination is able to be lowered and suspended from the line in the upright position without the riser contacting the sea bed. 
     
     
         16 . The method of  claim 12  to  15  wherein the catenary bend is supported above and clear of the sea bed. 
     
     
         17 . The method of  claim 13  or  14  including coupling multiple risers to the end support, the end support having multiple attachment means to support multiple risers.