Single Buoy Moorings Inc.

Seahorse Equipment Corporation

Thomas Prichard

Jeffrey Douglas Otten

Peimin Cao

Amir Salem

A top interface for subsea riser on offshore, floating vessel has an upper funnel and a co-axial lower funnel in spaced-apart relation. Tension loads on the riser are reacted at the upper funnel while lateral and bending loads are reacted at the lower funnel. The riser top interface may be used with flexible risers or steel catenary risers.

Steel catenary riser top interface

A removable riser hang-off connector is equipped with a flexible element that, in one embodiment, comprises rubber-encapsulated steel plates. The connector is designed for attachment to a hang-off collar provided on a steel catenary riser below the tapered stress joint or flex joint. Connection of the removable riser hang-off connector may be made by an ROV. With the removable riser hang-off connector attached, the tapered stress joint and/or flex joint may be raised out of the water (for inspection, maintenance, repair or replacement) by lifting the upper end of the SCR out of its porch receptacle with a chain jack (or other lifting device) and inserting the removable riser hang-off connector into the porch receptacle. This temporarily supports the SCR in an elevated state with the tapered stress joint and/or flex joint above the surface of the water.

Method and apparatus for elevating the tapered stress joint or flex joint of an SCR above the water

A top-tensioned riser system comprises a substantially vertical riser extending upward from the seafloor; a conductor surrounding an upper portion of the riser in spaced-apart relation; a coaxial keel guide surrounding a lower portion of the conductor; a tensioner attached to the conductor and the riser; a keel guide support structure attached to the keel guide and connected to the keel of a dry-tree, semi-submersible vessel; and, a keel joint centralizer attached to the riser proximate the keel guide and sized to prevent radial movement of the riser relative to the conductor. Side loads on the riser (such as those arising from displacement of the vessel from its nominal position or currents acting on the riser) are reacted from the riser to the conductor via the keel joint centralizer and then to the keel of the vessel via the keel guide.

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Houston, TX, United States of America

Thomas Prichard