Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A top-tensioned riser (TTR) is supported by a tensioning system on the deck of a floating platform. The tension ring may include an elastomeric layer which permits small angular and lateral displacements of the tension joint. The tension joint comprises a tapered section to resist the bending moment and shear imposed by the vessel's motion. The riser tension joint may be supported laterally by rollers below the tension ring. The rollers react on the tapered section when the riser strokes up and down. The tapered section may be engineered to maximize the use of the tension joint, and to reduce bending moment and shear loads imposed on the tensioning system. In certain embodiments, there may be a small gap between the rollers and the tapered section. In certain other embodiments, the rollers may be spring-loaded to increase the stability of surface equipment on the upper terminus of the riser.

Abstract: 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 thence to the keel of the vessel via the keel guide.

Abstract: A top-tensioned riser (TTR) is supported by a tensioning system on the deck of a floating platform. The tension ring may include an elastomeric layer which permits small angular and lateral displacements of the tension joint. The tension joint comprises a tapered section to resist the bending moment and shear imposed by the vessel's motion. The riser tension joint may be supported laterally by rollers below the tension ring. The rollers react on the tapered section when the riser strokes up and down. The tapered section may be engineered to maximize the use of the tension joint, and to reduce bending moment and shear loads imposed on the tensioning system. In certain embodiments, there may be a small gap between the rollers and the tapered section. In certain other embodiments, the rollers may be spring-loaded to increase the stability of surface equipment on the upper terminus of the riser.

Abstract: A tensioning device is provided for applying tension to a riser from a surface deck of an offshore oil or gas well. The tensioning device is used with a riser of the type having threads formed on an exterior surface thereof. A tension ring of the tensioning device is formed from first and second ring halves that are clamped together about the riser. The first and second halves have inner threads for engaging the threads of the riser. A clearance exists between the first and second ring halves when the ring halves are clamped together about the riser to allow the first and second ring halves to be tightened against the exterior surface of the riser so that the tension ring is securely fastened to the riser. Fastening means are used for clamping the first and second ring halves together about the riser. Tensioning members that couple at one end to the tension ring and at the other end to the surface deck are used to apply tension to the riser from the surface deck.