J. Ray Mcdermott, S.a.

Spartec, Inc.

Cheng-Yo Chen

James Allan Haney

Robin M Converse

Daniel Major Houser

William P Roberson

Charles F Kasischke

Gautam K Chaudhury

Thomas N Carr

Robert M Harrell

An improved strake for structures that are subject to vortex induced vibrations and motions due to fluid flow around the structure. One embodiment includes a streamliner on the edge of the strake. The streamliner may be added to existing strakes or may be formed at the same time as the strake for extruded strakes. The streamliner reduces vortex induced vibrations and motions of the structure to which the strake is attached. Another embodiment of the invention provides a tension resisting support attached to the strake and structure. The support provides a different load path along the strake than the previously known art for carrying the pressure loading from fluid pressure acting normal to the surface of the strake.

Strakes

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 compliant offshore platform wherein the sole foundation support for platform loads not provided by seawater buoyancy is provided by traditional skirt piles rigidly attached to the platform base near the ocean floor. Lateral flexibility of the platform is enhanced by the introduction of unbraced portal frames located throughout the platform framing in such a way as to facilitate lateral shearing displacements within the platform framing to the extent that the required compliant characteristics are obtained for the sway mode (first structural mode) of vibration while at the same time allowing the overturning moments generated by wind, wave, and current loads to be resisted by the vertical forces within the platform legs and platform foundation. The addition of these portal framed sections at selected locations into an otherwise traditional jacket provides a framing system with improved fundamental modes of vibration as are required for compliant structural behavior. In the preferred embodiment the platform skirt piles are rigidly attached to the jacket near the lowest levels of the jacket framing but somewhat above the seafloor. The skirt piles provide lateral restraint for the base of the platform.

Compliant offshore platform

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Houston, TX, United States of America

Cheng-Yo Chen