Abstract: A top tensioned riser extends substantially vertically from a platform hull to the seabottom. The riser includes length adjustment at its upper end and is detachably connected to an anchor pile at its lower end. Riser tension is monitored via load cells incorporated in the riser porch. The riser is connected to one or more import/export flowlines or pipelines.

Abstract: A tendon system for anchoring a floating platform to the seabed comprises composite tendon groups including one or more steel tendons in combination with tendons fabricated of synthetic materials. The synthetic composite tendons may be coaxially located within the steel tendons. Tendon resonance is inhibited by exerting damping forces through supplementary tendons/cables connecting a passive or active damping force system to the seabed. In another aspect of the invention, a passive tuned oscillator or an active driven mass oscillator provides damping of platform resonance motions.

Abstract: A floating platform for recovery of oil and gas from offshore oil and gas fields supports one or more decks above the water surface to accommodate equipment for drilling and processing oil, gas and water recovered from the oil and gas field. The platform includes a central column having a portion substantially below the water surface, and including a portion which extends above the water surface. The central column includes a base node and a plurality of pontoons extending outwardly therefrom and is anchored to the seabed by one or more tendons secured to the pontoons and to the seabed. Ballast modules fixedly or removably secured to the base node and/or the pontoons accept solid or liquid ballast for lowering the vertical center of gravity of the platform.

Abstract: A floating platform system supports one or more decks (14) above the water surface for accommodating equipment to process oil, gas and water recovered from a subsea hydrocarbon formation. The platform is secured to the seabed by one or more tendoms (17). A central column (12) of the platform includes a moonpool (19) extending axially through the central column (12). The moonpool (19) is open at the lower and upper ends thereof. Riser lateral restraint members (32) are supported within the moonpool (19) for laterally restraining risers (16) disposed in the moonpool (19) and minimizing riser spacing and riser deflection.

Abstract: A floating platform for recovery of oil and gas from offshore oil and gas fields supports one or more decks above the water surface to accommodate equipment for drilling and processing oil, gas and water recovered from the oil and gas field. The platform includes a central column having a portion substantially below the water surface, and including a portion which extends above the water surface. The central column includes a base node and a plurality of pontoons extending outwardly therefrom and is anchored to the seabed by one or more tendons secured to the pontoons and to the seabed. Ballast modules fixedly or removably secured to the base node and/or the pontoons accept solid or liquid ballast for lowering the vertical center of gravity of the platform.

Abstract: In a tension-leg mooring system a production platform supporting one or more decks above the water surface for accommodating equipment to process oil, gas, and water recovered from a subsea hydrocarbon formation is mounted on a single water surface piercing column formed by one or more buoyancy tanks located below the water surface. The surface piercing column includes a base structure comprising three or more pontoons extending radially outwardly from the bottom of the surface piercing column. The production platform is secured to the seabed by one or more tendons per pontoon which are secured to the pontoons at one end and anchored to foundation piles embedded in the seabed at the other end.