A SEMI-SUBMERSIBLE OFFSHORE LIFTING STRUCTURE, AND A METHOD FOR USING THE SAME

摘要

The present invention relates to a semi-submersible lifting structure (3) with controllable buoyancy for lifting offshore platforms (11) placed on jackets with jacket legs. The lifting structure (3) has two, in a longitudinal direction, first substantially parallel pontoons (4) and a between the two first substantially parallel pontoons (4) and, at one end of said first pontoons (4), extending transversal second pontoon (5) for connecting said first pontoons to form a first U, two longitudinal, substantially parallel first deck beams (7) and an, at one end of said first deck beams (7), extending transversal second deck beam (8) for connecting said first deck beams to form a second U. The columns (6) extends between the first U and the second U to form a unitary construction where the first U and the second U are substantially parallel. The structure is adapted to be rigidly attached to a second semi-submersible vessel (2) to form a complete lifting vessel (1). A method for using the lifting vessel (1) is also disclosed.