Spartec, Inc.

Mcdermott International, Inc.

Robin M Converse

James Allan Haney

Dennis E Calkins

Cheng-Yo Chen

Daniel Major Houser

Roger S Osborne

Charles F Kasischke

Young-Chan Park

Thomas N Carr

Young Chan Park

Robert M Harrell

Charles E Kindel

Changshi Mao

Gautam K Chaudhury

Raymond J Serpas

A riser joint keel assembly. A tapered riser joint is connected to a larger diameter outer sleeve through a connection that allows the tapered section and outer sleeve to function as one unit. In the combined design, the outer sleeve provides the required sliding interface between the riser and the guide at the keel of the hull while also providing some of the bending compliance needed to transition from the riser supported in the hull to the riser unsupported below the hull. The tapered section also provides the remaining bending compliance needed for the transition. The connection between the tapered and sleeve sections is a forged, machined ring plate welded to the bottom end of the sleeve, which provides a base for either bolted or threaded type attachment points for the tapered riser joint below the ring plate and the internal riser joint that continues to the surface.

Riser keel joint assembly

An improved floating circular hull construction arrangement. The hull is divided into sections by watertight flats. The flats are stiffened with angles or bulb tees curved to form concentric circles that are in turn supported by the radial girders spaced around the flats and spanning between the inner and outer-shells. In each section, longitudinal girders spaced radially around the inside of the outer-shell terminate at the flats and attach to the flats and do not penetrate the flats. The longitudinal girders are attached to flats aligned with the locations of the radial girders that extend across the flats to the inner and outer shells. A panel stiffening arrangement on the inner circumference of the outer shell is attached to the outer shell and the longitudinal girders. Longitudinal girders spaced around the outer circumference of the inner shell extend along the length of the inner shell and are attached to the radial girders. With the inner and outer longitudinal girders connected to the radial girders, moment resisting frames are created that are arranged radially in each compartment. These frames stiffen the individual girders as well as balance the differential axial loadings in the inner shell and outer shell surfaces. The compartments are assembled with the sections in a vertical orientation to minimize self-weight distortion during erection and to provide direct access with shop cranes during assembly of the full sections. The completed sections are rotated to the horizontal to be joined to the other sections to form a complete cylinder.

Cylindrical hull structural arrangement

An improved floating circular hull construction arrangement. The hull is divided into sections by watertight flats. In each section, longitudinal stiffeners spaced around the inside of the outer shell terminate adjacent the flats and do not penetrate the flats. The longitudinal stiffeners are supported by full rings that are concentric with the center of the hull. The rings are received over the longitudinal stiffeners, extend radially inward and are laterally supported with members configured to act in tension in either axial direction and which are parallel to the longitudinal axis of the hull. Rings on the inner shell extend radially outward toward the outer shell and may be laterally supported similarly to the lateral supports of the outer shell. The flats are stiffened with angles or bulb tees curved to form concentric circles that are in turn supported with radial girders spaced around the flats and spanning between the inner and outer shells. The compartments are assembled with the circular sections in a vertical orientation to minimize self-weight distortion during erection. The completed circular sections are rotated to the horizontal to be joined to the other sections to form a complete cylinder.

Cylindrical hull structure

A method for fabricating sections of a floating offshore spar type structure and mating the sections offshore. A buoyant hard tank is fabricated vertically. The hard tank is then transported in a vertical orientation to a site where it is mated to a truss section of the spar structure offshore while the hard tank and truss section are both in the vertical orientation. The mated tank and truss sections are then towed in the vertical orientation to the operational site. The hard tank is fabricated with a larger diameter and correspondingly shallower draft than a more traditionally proportioned hard tank.

Method for fabricating and assembling a floating offshore structure

A fixed, non-compliant, non-floating offshore platform subject to lower wave, wind, current, and rig loadings resulting from a configuration that supports the portion of the well casings that extend from near the seafloor to a deck level above the water surface using tension instead of intermediate lateral supports. Only the smallest one or two well casings among all those that comprise the well casing system are extended back from the seafloor, which further reduces the lateral loadings on the structure.

Fixed offshore platform structures, using small diameter, tensioned,

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Houston, TX, United States of America

Robin M Converse