Patent ID: 6659690
Filing Date: 2003-12-09
Classification: E21B,F16L

Abstract:
A subsea production riser for connecting a surface structure to subsea equipment, the riser comprising:a string of production riser sections extending from an upper end near the surface structure to a lower end near the subsea equipment, the riser sections having an outer diameter; an upper riser transition section extending below and having an upper end joined to a lower end of the string of production riser sections, the upper riser transition section tapering from a larger outer diameter at the upper end of the upper riser transition section to a smaller outer diameter at a lower end of the upper riser transition section; a cylindrical intermediate riser section below the upper riser transition section and having an outer diameter that is the same as the smaller outer diameter of the upper riser transition section; and a lower riser transition section below the intermediate riser section and tapering from the outer diameter of the intermediate riser section to a lower outer diameter larger than the outer diameter of the upper end of the upper riser transition section.