Marine riser

In a tubular joint for use in a marine riser adapted to be suspended from a vessel for releasable connection at its lower end to a subsea terminal, the improvement comprising,

• a body about the joint having passageway means therethrough opening to each end of the body for disrupting smooth flow along the length of the riser and thereby damping the vertical oscillation of the riser when released from the subsea terminal.

In a tubular joint for use in a marine riser adapted to be suspended from a vessel for releasable connection at its lower end to a subsea terminal, the improvement comprising,

• a body of bouyant material carried about the joint having passageway means therethrough opening to each end of the body for disrupting smooth flow along the length of the riser and thereby damping the vertical oscillation of the riser when released from the subsea terminal.

In a tubular joint for use in a marine riser adapted to be suspended from a vessel for releasable connection at its lower end to a subsea terminal, the improvement comprising,

• a body formed integrally with and about the joint having passageway means therethrough opening to each end of the body for disrupting smooth flow along the length of the riser and thereby damping the vertical oscillation of the riser when released from the subsea terminal.

In apparatus for use in drilling an offshore well wherein a marine riser suspended from a vessel is releasably connected at its lower end to a subsea terminal, the improvement comprising

• a body about the riser having passageway means therethrough opening to each end of the riser for disrupting smooth flow along the length of the riser and thereby damping its vertical oscillation when released from the subsea terminal.

In apparatus for use in producing an offshore well wherein a marine riser suspended from a vessel is releasably connected at its lower end to a subsea terminal, the improvement comprising

• a body about the riser having passageway means therethrough opening to each end of the riser for disrupting smooth flow along the length of the riser and thereby damping its vertical oscillation when released from the subsea terminal.

In a marine riser adapted to be suspended from a vessel and releasably connected at its lower end to a subsea terminal, the improvement comprising

• baffles extending outwardly from the riser for disrupting smooth flow along its length and thereby damping the vertical oscillation of the riser when released from the subsea terminal.

In a maring riser adapted to be suspended from a vessel and releasably connected at its lower end to a subsea terminal, the improvement comprising

• means forming a more restricted passageway to flow in one longitudinal direction along its length than the other and thereby damping the vertical oscillation of the riser when released from the subsea terminal.

In a tubular joint for use in a marine riser adapted to be suspended from a vessel for releasable connection at its lower end to a subsea terminal, the improvement comprising

• baffles extending outwardly from the joint for disrupting smooth flow along its length and thereby damping the vertical oscillation of the riser when released from the subsea terminal.

In a tubular joint for use in a marine riser adapted to be suspended from a vessel for releasable connection at its lower end to a subsea terminal, the improvement comprising

• one way valve means to allow fluid passage along the length of the joint when the joint moves in one vertical direction and to block fluid when the joint moves in the opposite direction, to thereby damp the vertical oscillation of the riser when released from the subsea terminal.