Freestanding Hybrid Riser System Including a Bottom Configuration with a Flexible Pipe Joint and a Diverless Pipe Connector

Abstract

A freestanding hybrid riser system includes a steel pipe riser having a bottom end anchored to a foundation on a seabed through a flexible joint and a diverless pipe connector. A tube is mounted to the foundation and connected to the diverless pipe connector for providing a static connection to a subsea pipeline on the seabed for a flow of fluid between the steel pipe and the subsea pipeline and through the flexible pipe joint and through the diverless pipe connector and through the tube. In a preferred implementation, the flexible pipe joint includes alternate elastomer layers and metal layers reinforcing the elastomer layers, and a receptacle of the diverless connector is mounted on a foundation such as a suction pile on the seabed, or a pile grouted in a bore in the seabed.

What is claimed is: 
     
         1 . A freestanding hybrid riser system comprising:
 a vertical steel pipe having a top end and a bottom end;   a floating tank coupled to the top end of the vertical steel pipe for supporting the vertical steel pipe;   a flexible pipe joint;   a diverless pipe connector attached to the flexible pipe joint;   a foundation mounted on a seabed, and the bottom end of the vertical steel pipe being anchored to the foundation through the flexible pipe joint and the diverless pipe connector; and   a tube mounted to the foundation and connected to the diverless pipe connector for providing a static connection to a subsea pipeline on the seabed for a flow of fluid between the vertical steel pipe and the subsea pipeline and through the flexible pipe joint and through the diverless pipe connector and through the tube.   
     
     
         2 . The freestanding hybrid riser system as claimed in  claim 1 , wherein the flexible pipe joint includes alternate elastomer layers and metal layers reinforcing the elastomer layers. 
     
     
         3 . The freestanding hybrid riser system as claimed in  claim 1 , wherein the flexible pipe joint has an upper end attached to the bottom end of the vertical steel pipe, and the flexible pipe joint has a lower end attached to the diverless pipe connector. 
     
     
         4 . The freestanding hybrid riser system as claimed in  claim 1 , wherein the flexible pipe joint has an upper end attached to the bottom end of the vertical steel pipe, the diverless pipe connector has a connector hub attached to a lower end of the flexible pipe joint, and the diverless pipe connector has a connector receptacle mounted to the foundation, and the tube has an upper end attached to the connector receptacle and provides a vertical-to-horizontal transition from the diverless pipe connector to the static connection to the subsea pipeline. 
     
     
         5 . The freestanding hybrid riser system as claimed in  claim 1 , wherein the tube is a J-tube having an upper end attached to a receptacle of the diverless pipe connector, and the J-tube has a lower end for providing the static connection to the subsea pipeline. 
     
     
         6 . The freestanding hybrid riser system as claimed in  claim 1 , wherein the foundation includes a suction pile, and the tube passes through the suction pile. 
     
     
         7 . The freestanding hybrid riser system as claimed in  claim 1 , wherein the foundation includes a pile grouted in a bore in the seabed, and the tube extends from a branch fitting mounted on top of the pile. 
     
     
         8 . A bottom configuration for a freestanding hybrid riser system, the bottom configuration comprising:
 a flexible pipe joint;   a diverless pipe connector attached to the flexible pipe joint; and   a tube connected to the diverless pipe connector for providing a vertical-to-horizontal transition from the diverless pipe connector for conveying fluid when the fluid flows through the flexible pipe joint and through the diverless pipe connector.   
     
     
         9 . The bottom configuration for a freestanding hybrid riser system as claimed in  claim 8 , wherein the flexible pipe joint includes alternate elastomer layers and metal layers reinforcing the elastomer layers. 
     
     
         10 . The bottom configuration for a freestanding hybrid riser system as claimed in  claim 8 , wherein the flexible pipe joint has an upper end configured for attachment to a lower end of a vertical steel pipe of a riser, and the diverless pipe connector has a hub attached to a lower end of the flexible pipe joint, and the diverless pipe connector has a receptacle configured for engaging the diverless pipe connector hub, and the tube has an upper end attached to the diverless pipe connector receptacle for conveying the fluid when the diverless pipe connector hub is engaged in the diverless pipe connector receptacle and fluid flows through the flexible pipe joint, through the diverless pipe connector hub, through the diverless pipe connector receptacle, and through the tube. 
     
     
         11 . The bottom configuration for a freestanding hybrid riser system as claimed in  claim 8 , further comprising a suction pile upon which the diverless pipe connector is mounted, and the tube passes through the suction pile. 
     
     
         12 . The bottom configuration for a freestanding hybrid riser system as claimed in  claim 8 , further comprising a branch fitting upon which the diverless pipe connector is mounted, and the branch fitting has a first arm configured for attachment to an upper end of a pile, and the branch fitting has a second arm attached to the tube. 
     
     
         13 . A method of installing a freestanding hybrid riser to assemble a freestanding hybrid riser system, the freestanding hybrid riser including a steel pipe having a top end and a bottom end, said method comprising:
 (a) installing a foundation structure upon a seabed, the foundation structure including a foundation on the seabed and a tube mounted on the foundation for providing a static connection to a subsea pipeline on the seabed;   (b) orienting the steel pipe over the foundation structure; and   (c) engaging a diverless pipe connector to anchor the bottom end of the steel pipe to the foundation structure and to complete a connection between the bottom end of the steel pipe and the foundation structure, the connection including a flexible pipe joint and the diverless pipe connector between the bottom end of the steel pipe and the tube for a flow of fluid between the bottom end of the steel pipe and the subsea pipeline, and through the flexible pipe joint, through the diverless pipe connector, and through the tube.   
     
     
         14 . The method as claimed in  claim 13 , which includes attaching a first end of the flexible pipe joint to the bottom end of the steel pipe, and wherein the engaging of the diverless pipe connector mounts a second end of the flexible pipe joint to the foundation structure. 
     
     
         15 . The method as claimed in  claim 14 , wherein the second end of the flexible pipe joint is terminated by a diverless pipe connector hub, and a receptacle of the diverless pipe connector is mounted to the foundation structure, and the method includes landing the hub of the diverless pipe connector in the receptacle to mount the second end of the flexible pipe joint to the foundation structure. 
     
     
         16 . The method as claimed in  claim 15 , wherein the receptacle for the diverless pipe connector has an engagement mechanism for locking the diverless pipe connector hub into a fixed engagement position with respect to the receptacle, and the method further includes orienting the steel pipe in a vertical position once the diverless pipe connector hub has been landed into the receptacle, and then actuating the engagement mechanism to lock the diverless pipe connector hub into the fixed engagement position with respect to the receptacle. 
     
     
         17 . The method as claimed in  claim 15 , wherein the diverless pipe connector hub becomes engaged with the receptacle when the diverless pipe connector hub is landed into the receptacle, and the method further includes thereafter increasing buoyancy of a floating tank supporting the steel pipe in order to place the steel pipe in a state of tension for stability.