Method and apparatus for disconnecting and retrieving multiple risers attached to a floating vessel

In combination with a floating vessel having a generally cylindrical turret mounted within a vertical opening in said vessel with the sea level positioned intermediate the length of said turret, the turret having a plurality of product conduits thereon;

• a riser buoy releasably docked within said turret;
• a plurality of flexible risers having upper ends mounted on said riser buoy and extending downwardly to the sea bottom for the transport of product from subsea wells;
• a plurality of couplings for releasably establishing flow paths between said flexible risers and said product conduits on said turret;
• a buoy weight coupled to said riser buoy by a buoy anchor line,
• means for raising said buoy anchor line until said weight is within said turret beneath said buoy and for lowering said buoy anchor line downward until said weight is below said buoy at a predetermined length, such that after release of said riser buoy from said turret, said weight is supported on the sea bottom with said riser buoy extending upwardly in the sea at a predetermined distance corresponding to said predetermined length.

A riser support structure for supporting flexible risers within a generally cylindrical turret mounted in a vertical opening of a vessel, the turret having a plurality of product conduits disposed therein for releasable connection to said flexible risers;

• said riser support structure comprising:
• mooring lines connected directly to said turret for anchoring said turret to the sea bed;
• a riser buoy arranged and designed for docking within said turret independently of said mooring lines;
• means for releasably docking said riser buoy within said turret;
• a plurality of flexible risers having upper ends connected to product flow paths of said riser buoy;
• said risers extending downwardly to the sea bed for the transport of product;
• and
• a plurality of couplings for releasably connecting said product flow paths to said product conduits on said turret at a location within said cylindrical turret.

A riser support structure for supporting flexible risers within a generally cylindrical turret mounted in a vertical opening of a vessel, the turret having a plurality of product conduits disposed therein for releasable connection to said flexible risers;

• said riser support structure comprising:
• positioning means for positioning said vessel in the sea;
• a riser buoy arranged and designed for docking within said turret independently of said positioning means;
• means for releasably docking said riser buoy within said turret;
• a plurality of flexible risers having upper ends connected to product flow paths of said riser buoy;
• said risers extending downwardly to the sea bed for the transport of product;
• a plurality of couplings for releasably connecting said product flow paths to said product conduits on said turret at a location within said cylindrical turret,
• wherein said means for releasbly docking includes,
• a retrieval line connected to said riser buoy;
• and
• winch means on said vessel for pulling said retrieval line and said riser buoy to a docked position within said turret, and
• further comprising:
• a weight connected to a lower end of said retrieval line which is arranged and designed to be pulled tightly against said riser buoy in said docked position of the riser buoy.