System for accommodating motion of a floating body

Abstract

A system is provided for compensation for motion of a floating platform connected to a riser having at least two segments connected by an elbow. According to various example embodiments, a pre-determined portion of the riser flex in response to heave of the platform. In various example embodiments, the pre-determined portion comprises pre-formed curves that flex in response to the heave of the platform.

What is claimed is:  
     
         1 . A system for accommodating motion of a floating body connected to a seafloor wellhead, the system comprising: 
 a substantially vertical riser segment to be suspended from a floating-body such that a top portion of the substantially vertical riser segment moves as the floating body moves,    a substantially horizontal wellhead entry pipe to be connected to a wellhead, and    an angled segment connecting the substantially vertical riser segment and the wellhead entry pipe such that the angled segment is positioned with respect to the substantially vertical riser segment and the substantially horizontal segment to move in response to motion of the floating body.    
     
     
         2 . A system as in  claim 1 , wherein the substantially vertical riser segment comprises a substantially straight pipe.  
     
     
         3 . A system as in  claim 1 , wherein the substantially horizontal wellhead entry pipe comprises a substantially straight pipe.  
     
     
         4 . A system as in  claim 1 , wherein the substantially vertical riser segment comprises pre-formed, helical curves in a pre-determined flex portion.  
     
     
         5 . A system as in  claim 1  wherein the substantially vertical riser segment comprises pre-formed single-planar curves.  
     
     
         6 . A system as in  claim 5  wherein the single-planar curves comprise arched curves.  
     
     
         7 . A system as in  claim 1  wherein the substantially horizontal wellhead entry pipe comprises at least one pre-determined flex portion.  
     
     
         8 . A system as in  claim 7  wherein the pre-determined flex portion comprises pre-formed curves.  
     
     
         9 . A system as in  claim 8  wherein the pre-formed curves comprise helical curves.  
     
     
         10 . A system as in  claim 8  wherein the pre-formed curves comprise single-plane curves.  
     
     
         11 . A system as in  claim 8  wherein the pre-formed curves comprise arched curves.  
     
     
         12 . A system as in  claim 7  wherein the pre-determined flex portion comprises a substantially straight portion formed to flex more than other portions.