Patent ID: 7416025
Filing Date: 2008-08-26
Classification: B63B,E21B

Abstract:
1. A variable tension riser to connect a subsea wellhead, a subsea flowline end termination (FLET) or a subsea pipe line end termination (PLET) to a floating platform, comprising: a negatively buoyant region, a weighted region, a variable buoyant region, a positively buoyant region, and a tensioned region; wherein the negatively buoyant region and the weighted region hang below the floating platform; wherein the weighted region is intermediate the negatively buoyant region and the variable buoyant region; wherein the variable buoyant region is located between the weighted region and the tensioned region; wherein the positively buoyant region is positioned to create positive tension in the tensioned region; wherein the tensioned region is connected to the FLET, PLET, or subsea wellhead; wherein the variable tension riser includes a stress joint proximate to a distal end of the floating platform; and wherein the stress joint is connected to a keel joint guided with a keel guide connected to the distal end of the floating platform; and a communications conduit to allow communications from the floating platform to a wellbore of the subsea wellhead, FLET, or PLET.