Patent ID: 8430170
Filing Date: 2013-04-30
Classification: E21B

Abstract:
1. A bottom-to-surface connection installation at a great depth of more than 1000 m, the installation comprising: a) at least one substantially vertical rigid rising pipe comprising a vertical riser fastened at a bottom end to an anchor device at the sea bottom; and b) at least one flexible connection pipe providing a connection between a floating support and a top end of said vertical riser; and c) one end of said flexible pipe directly connected without a gooseneck device to the top end of said vertical riser of the vertical rigid rising pipe; and d) the bottom end of said vertical riser comprising a terminal rigid pipe element of a length of at least 10 m enabling a rigid clamped connection, said terminal pipe element forming an inertia transition piece in which inertia varies in such a manner that the inertia of said terminal pipe element at a top end is substantially equal to that of a pipe element of a main portion of the vertical riser to which the terminal pipe element is connected, said inertia of the terminal pipe element increasing progressively down to a bottom end of said inertia transition piece, and including a first fastening flange enabling the bottom end of said vertical riser to be clamped at said anchor device at the sea bottom, wherein, a terminal portion of the flexible pipe adjacent to a junction of the flexible pipe with the top end of said vertical riser presents positive buoyancy, and at least the top portion of said vertical riser presents positive buoyancy, such that the positive buoyancies of said terminal portion of the flexible pipe and said top portion of said vertical riser enable said vertical riser to be tensioned in a substantially vertical position and enable alignment or continuity of curvature to be achieved between the end of said terminal portion of the flexible pipe and the top portion of said vertical riser at which the flexible pipe and the vertical riser are directly connected together, said positive buoyancy being provided by at least one of a regularly spaced apart plurality of coaxial peripheral floats and a continuous coating of positive buoyancy material; and said terminal portion of the flexible pipe presenting positive buoyancy extends over a fraction of the total length of the flexible pipe, such that the flexible pipe presents an S-shaped configuration, with a first portion of said flexible pipe beside said floating support presenting concave curvature in the form of a catenary in a diving catenary configuration and said remaining terminal portion of said flexible pipe presenting convex curvature in an inverted catenary shape as a result of the positive buoyancy of the terminal portion of the flexible pipe, the end of said terminal portion of the flexible pipe at the top end of said vertical riser being situated above and substantially in alignment with the axis Z