Abstract: A riser tensioner system and a wellbay structure for a floating unit or platform for deep/ultra-deep water field development. The riser tensioner system includes a first cassette, a second cassette, a tension joint, one or more centralizers, and a plurality of cylinders. The one or more centralizers provide lateral support to the tension joint. Each of the plurality of cylinders comprises a first end, a second end, and an intermediate portion. The first end of each of the plurality of cylinders is secured to the first cassette, and an intermediate portion of each of the plurality of cylinders is secured to the second cassette. The wellbay structure includes a plurality of transverse girders and a plurality of longitudinal girders. The girders form a grid comprising a plurality of slots. Each of the plurality of slots is configured for receiving and supporting a first cassette of each a riser tensioner assembly.

Abstract: An offshore floating structure (10) for the drilling and production of oil and gas includes a generally circular toroidal, hollow pontoon (11) of substantially the same radial width throughout a perimeter of the pontoon. The offshore floating structure includes a plurality of columns (12) of substantially a same cross-sectional area, each coupled at a coupling point, on a bottom end thereof to the pontoon at an equidistant point along the perimeter of the pontoon, and adapted to be coupled on a top end to a deck structure. The diameter (23) from a center of the radial width of the pontoon is greater than a distance (21) from a center of one column to a center of an adjacent column.

Abstract: A deep draft semi-submersible production and drilling platform unit with dry trees is described. The platform unit preferably comprises four columns, a ring pontoon, a two-axis symmetrical hull with draft in the range of 100 to 155 feet, top-tensioned risers with push or pull tensioners of preferred combined vertical stiffness of 10% to 30% of the platform water plane stiffness, a wellbay with a well spacing in the range of 12 to 18 feet, a riser guiding system supported by the pontoons or at an elevated level, topside facilities supported by a box type of deck structure, mooring lines, and catenary risers.

Abstract: An offshore floating structure (10) for the drilling and production of oil and gas includes a generally circular toroidal, hollow pontoon (11) of substantially the same radial width throughout a perimeter of the pontoon. The offshore floating structure includes a plurality of columns (12) of substantially a same cross-sectional area, each coupled at a coupling point, on a bottom end thereof to the pontoon at an equidistant point along the perimeter of the pontoon, and adapted to be coupled on a top end to a deck structure. The diameter (23) from a center of the radial width of the pontoon is greater than a distance (21) from a center of one column to a center of an adjacent column.

Abstract: A deep draft semi-submersible production and drilling platform unit with dry trees is described. The platform unit preferably comprises four columns, a ring pontoon, a two-axis symmetrical hull with draft in the range of 100 to 155 feet, top-tensioned risers with push or pull tensioners of preferred combined vertical stiffness of 10% to 30% of the platform water plane stiffness, a well-bay with a well spacing in the range of 12 to 18 feet, a riser guiding system supported by the pontoons or at an elevated level, topside facilities supported by a box type of deck structure, mooring lines, and catenary risers.