Patent ID: 8869901
Filing Date: 2014-10-28
Classification: E21B,F16L

Abstract:
1. An offshore drilling system for water depths greater than 1000 m and for reservoir pressure of at least 10,000 psi, comprising a floating vessel, a well drilled in the sea bottom, a tubular riser extending the well up to the floating vessel, and an aerial wellhead comprising a blowout preventer fastened to the end of the riser at the level of the floating vessel, characterized in that said riser comprises tubular elements connected to one another by high-pressure connectors able to withstand the internal pressure of the well, in that each of said tubular elements comprises a metallic tubular body hooped by windings of fibers coated with a polymer matrix, and in that the riser comprises several sections, each section comprising at least one of said tubular elements and having a hoop stress as a function of the depth at which the section lies and of the mechanical strength of said tubular body, wherein at least one of said several sections has different hoop stress than at least one other of said several sections and wherein the various sections have metallic tubular bodies of the same steel grade and of constant geometry throughout the riser, and the various sections have different hoop thicknesses, the hoop thickness of the several sections decreasing with depth.