Patent ID: 7104329

Claim:
A marine riser assembly, comprising: (a) a relatively rigid, vertical, relatively long upper section adapted to be carried by a facility floating on the surface of a body of water, having an upper end adapted to be in flow communication with said facility, and having a lower end; (b) a relatively rigid, vertical, relatively short lower section adapted to be secured to the seafloor, having a lower end to be in flow communication with a fluid system carried by the seafloor, and having an upper end; (c) extensible means for flexibly connecting said upper section to said lower section, said extensible means having one end connected to said upper end of said lower riser section and in flow communication therewith, and having an opposite end connected to said lower end of said upper riser section and in flow communication therewith; and (d) tensioning means mechanically connecting said one end of said extensible means to said opposite end of said extensible means, for biasing said upper riser section towards said lower riser section and thereby resisting relative movement between said floating facility and said lower end of said lower riser section, wherein said tensioning means comprises: (i) a cylinder, having one end for being open to sea pressure, having an opposite end sealed from sea pressure, and connected to one of said upper section and said lower section; (ii) a piston within said cylinder slidingly and sealingly disposed for movement within said cylinder; and (iii) a piston rod sealingly and slidingly disposed for movement through said opposite end of said cylinder, having one end connected to said piston, and having an opposite end connected to the other of said upper section and said lower section.