Fmc Technologies, Inc.

Other

Roy H Cottrell

L Terry Boatman

Yonghui Liu

Jose H Vazquez

Brent A Salyer

Martin Matthew Duensing

Barton D Grasso

Frank Strachan

Caspar Heyl

Richard H Gunderson

Vernon Raymond Jenkins

Rick A Hall

Semi-submersibles are subjected to loading from waves, causing racking, longitudinal shear and parallelogramming, or differential movement of the pontoons. The cyclic wave loading makes the various connections, where stress concentrations occur, susceptible to fatigue damage throughout the hull structure. This is most evident at the connections between the braces and the main hull structure. A revised brace to main hull connection with reduced bending stiffness is employed to reduce the moment being transferred from the brace to the hull, thereby reducing the bending stress and susceptibility to fatigue damage. This improved connection employs an internal member to transfer the loads between the brace and hull structure mainly as tension and compression. As a consequence of the improved fatigue performance, the structural weight of the connection can be greatly reduced, thus increasing the capacity with which the semi-submersible hull can operate.

Bending stiffness reducer for brace to hull connection

A mooring arrangement between a floating storage body spread moored in deep water and a shuttle tanker, the arrangement including a single point buoyant member that is adapted for mooring a shuttle tanker in offloading position relative to a floating production, storage and offloading vessel (FPSO) with a link between the floating storage body and the single point buoyant member. One embodiment () of the invention employs a submerged yoke (), having one end () rotatably coupled to a FPSO () and a second end (), supported by a buoy. A mooring hawser () extends from the buoy to the shuttle tanker and product hoses connect the shuttle tanker with the FPSO and extend along the submerged yoke. In another embodiment, the mooring buoy is stationed by a hold-back mooring system () and the FPSO or the tanker or both is provide with traction device () to move the tanker into loading position with respect to the FPSO. Other embodiments of the invention establish mooring of a shuttle tanker so that it can weathervane 360 degrees during offloading activity. In another embodiment, the mooring buoy () is provided with a dynamic positioning system () for controlling shuttle tanker positioning with respect to conditions of the environment or for moving the tanker to a desired position during loading.

Offloading arrangements and method for spread moored FPSOs

A swing arm type chain support with a hook arrangement integral with a swing arm which allows a mooring chain to ratchet over the hook while tensioning, then automatically engage the hook when tension is reduced.

Swing arm chain support method

A floating offshore platform configuration is provided, which decouples pitch, roll, and heave motions from acting on tensioned risers and accommodates the angular displacement induced by floating offshore platform surge and/or sway excursion without inducing bending in the riser at its entrance to the floating offshore platform. The risers are guided by an inner structure that is tethered from the sea floor and centered inside an outer hull structure. Outer hull structure heave, pitch and roll motions are substantially isolated from acting on the inner structure through a connection mechanism, and each riser is allowed to individually expand or contract.

Riser support for floating offshore structure

An arrangement for suspending a Single Point Mooring Turret from its corresponding vessel, by transmitting a circumferentially uniform axial vertical load without moment through the interface of motion between the vessel and turret, by decoupling mooring system loads, inertial loads and hull deflection induced loads, from transmission across that interface. The arrangement supports the turret through a pendular suspension system which includes bogies, having one or more wheels or rollers per bogie, which roll around the circumference of the moonpool on a rail to allow the bogies to rotate in a horizontal plane which is perpendicular to the center line of the moonpool, and to decouple the bearing loads from radial hull deflection due to ovaling caused by rough seas. Radial flexure is achieved by suspending the turret from the bogie through rocker arms and chains, cables, rods or columns between the bogies and a riser support structure of the turret.

Single point mooring with suspension turret

A buoyant hybrid riser/tension (BHRT) member moors a floating body on the sea surface to a pipeline terminated at a submerged structure. The BHRT includes one or more conduits, one or more tension members, and buoyancy. The conduits provide fluid communication from the pipeline at the submerged structure the tension member absorbs the mooring load and the buoyancy cooperates with the tension member to produce a soft restoring force for mooring the floating body to the submerged structure. The BHRT lower end connection allows angular, but not torsional displacement with respect to the submerged structure. In one arrangement of the BHRT lower end, localized flexing is allowed in the separate conductors via bend stiffeners. At the BHRT upper end, several arrangements for the connection between the BHRT and floating body are provided. In one arrangement, a rigid connection is established between a male coupler at an upper end of the BHRT and a female coupler on the floating body. In a second arrangement, the upper end of the BHRT includes a riser end buoy with a mating surface that connects with a female receptacle mounted on a bearing assembly on the floating body. On top of the female receptacle is an ESD valve block and a swivel (in one arrangement) or a manifold block (in another arrangement). The BHRT can &ldquo;wind up&rdquo; in torsion when the floating body weathervaning. Such wind up can be undone by temporarily releasing a brake which normally secures the female coupling to the floating vessel and allowing the BHRT and female coupling to rotate backward with respect to the floating vessel.

Hybrid buoyant riser/tension mooring system

A mooring system including a body/arm/vessel arrangement with passive damping and/or an active force restoring system. The active force restoring system includes a sensor for generating a displacement signal representative of the displacement of the vessel from a quiescent position and an active forcing device which responds to the displacement signal to force the arm in a direction to move the vessel toward the quiescent position. The passive damping arrangement includes a device, independent of and in addition to the damping of the water on the vessel or the arm, that damps the oscillation of the vessel in response to environmental conditions which force the vessel from its quiescent position. Hydraulic cylinder arrangements are provided for active forcing and passive damping. Powered winch/cable arrangements are also provided for active force systems. Alternative devices for active and passive damping systems of torque actuators include hydraulic powered cans with internal fins, or cans with internal elastomeric elements or disk brake elements.

Growing community of inventors

Cypress, TX, United States of America

Roy H Cottrell