Method and apparatus for facilitating hang off of multiple top tension riser or umbilicals from a compensated tensioning deck

Abstract

The disclosure provides a deck tensioning system, supporting multiple risers, that is coupled to an offshore platform and compensated for heave and horizontal movement. Such a tensioning system provides simplified access to the production trees on the risers. The tensioning system provides tensioning for a tensioning deck to which the multiple risers are coupled, while reducing the tensioning cylinders for individual risers. The deck tensioning system further provides a simplified tension flex connector (“TFC”) with an intermediate movable member for each riser. The TFC assists in absorbing and/or adjusting for forces that may cause the tensioning deck to pitch and roll from the interactions between the multiple risers coupled to the tensioning deck as a unitary structure. If a fire or other event causes damage to the tension flex connector, the tension flex connector is designed to maintain a supporting connection with the riser without the intermediate movable member.

1 . A deck tensioning system for an offshore floating platform having a plurality of risers extending downward from the platform and suspended from the platform, comprising:
 a tensioning deck having a frame, the frame defining a plurality of openings adapted to receive the plurality of risers;   a plurality of flexibly mounted control cylinders adapted to suspend the tensioning deck from the platform, the control cylinders coupled with flexible connections to the tensioning deck, the platform, or a combination thereof, the flexible connections adapted to allow the tensioning deck to move in at least one horizontal direction relative to the platform; and   a plurality of tension flex connectors coupled between the tensioning deck and the risers, the tension flex connectors disposed in the openings of the frame, the tension flex connectors adapted to allow the risers to move at angles to the tensioning deck while the tension flex connectors support the risers to the tensioning deck.   
     
     
         2 . The system of  claim 1 , wherein the flexible connections of the control cylinders are adapted to allow the tensioning deck to move in multiple horizontal directions relative to the offshore floating platform. 
     
     
         3 . The system of  claim 1 , wherein the control cylinders are adapted to control vertical movement of the tensioning deck and the risers coupled to the tensioning deck relative to the offshore floating platform. 
     
     
         4 . The system of  claim 1 , wherein relative vertical movement of the risers to the tensioning deck are fixed by the tension flex connectors. 
     
     
         5 . The system of  claim 1 , wherein the tension flex connectors comprise an inner body and an outer body and the outer body is adapted to resist a downward movement of the inner body through the outer body. 
     
     
         6 . A method of supporting a riser from an offshore floating platform, comprising:
 supporting a tensioning deck from the offshore floating platform, the tensioning deck having a frame;   allowing the frame to move in at least one horizontal direction and a vertical direction relative to the platform;   supporting a plurality of risers from the tensioning deck; and   allowing the risers to move angularly relative to the tensioning deck.   
     
     
         7 . The method of  claim 6 , wherein allowing the frame to move in the at least one horizontal direction comprises allowing the frame to move in multiple horizontal directions relative to the offshore floating platform. 
     
     
         8 . The method of  claim 6 , wherein allowing the frame to move in the at least one horizontal direction and the vertical direction relative to the platform comprises allowing the frame to move relative to pitch, roll, and yaw of the platform.