Method and apparatus for suction anchor and mooring deployment and connection

Abstract

A method and apparatus for deployment of mooring systems for buoyant marine structures such as mobile offshore drilling units (MODU's) and for connecting the same to the mooring lines thereof. An anchor handling vessel carries one or more anchors each having a deployment connection and a mooring connection and individually moves each anchor over its stern roller and deploys it to the sea bottom for installation. A handling line is disconnected by ROV from the deployment connection and is moved from the deployment connection to the mooring connection so as to become the main mooring line. Syntactic buoys are then mounted on the main mooring line for elevating it above the sea bottom for recovery. When MODU stationing is desired the anchor handling vessel then recovers the surface buoy and connects to the rig mooring line using a short section of mooring chain. A J-chaser stopper device is then installed in the mooring string and is connected to the mooring line of the MODU by a short section of chain. The J-chaser lowers the mooring string, completing the mooring connection between the anchor and the MODU. A plurality of mooring strings, typically eight, are deployed in this manner to properly station the MODU. Disconnection of the MODU is accomplished essentially by the reverse of the above deployment procedure.

1 . A method for deployment of mooring systems for mobile offshore drilling units and for connecting the same to the mooring lines thereof, comprising: 
 (a) providing an anchor handling vessel having a stern roller and having at least one suction anchor thereon having a deployment connection and a mooring connection, said anchor handling vessel having an anchor deployment mechanism incorporating a handling wire having a quick-disconnect socket connector for accomplishing movement of said suction anchor over said stern roller for line deployment to the sea bottom;    (b) after deployment of said suction anchor, disconnecting said handling wire from said deployment connection and moving said anchor handling wire from said deployment connection to said mooring connection, said handling wire becoming the main mooring wire;    (c) connecting syntactic buoy means with said main mooring wire for elevating said main mooring wire for recovery; and    (d) repeating said method steps (a)-(c) for each plurality suction anchors and mooring wires.    
     
     
         2 . A method for stationing a mobile offshore drilling rig to a pre-deployed rig mooring system having a plurality of suction anchors to which is connected a plurality of mooring wires having syntactic buoys elevating the ends of the mooring wires above the sea bottom, comprising: 
 (a) recovering said syntactic buoys with the lifting winch of a service vessel;    (b) connecting said mooring wires to the mooring wires of said mobile offshore drilling unit;    (c) attaching a length of chain to each of said mooring wires and installing a J-chaser stopper device to said length of chain, the mooring wire, chain and J-chaser stopper being a mooring string;    (d) lowering the mooring string from the service vessel with a J-chaser to permit said mobile offshore drilling unit to accept the weight of said mooring string; and    (e) with said service vessel, sliding said J-chaser along said mooring wire toward said mobile offshore drilling unit until said J-chaser moves free of said mooring wire.