Method for fabricating and transporting an integrated buoyancy system

Abstract

A buoyancy system includes a plurality of buoyancy joints distributed along a riser system. Each joint can include a riser pipe, an external frame disposed around a riser and a vessel, and a buoyant cladding disposed between the vessel and the frame.

1 . A method for transporting and installing buoyancy for a riser of an offshore platform, comprising the steps of:
 a) providing a plurality of buoyancy joints, each buoyancy joint having an external frame with a lateral perimeter having at least three linear sides;   b) bundling the plurality of buoyancy joints together in a bundled configuration with the buoyancy joints laterally adjacent one another and the linear sides of adjacent buoyancy joints abutting one another;   c) transporting the plurality of buoyancy joints in the bundled configuration from a manufacturing site to a field site; and   d) disposing the plurality of buoyancy joints along a riser system extending submerged between the offshore platform and a wellhead with riser sections of the buoyancy joints operatively coupled in series and in fluid communication with riser sections of the riser system.   
   
   
       2 . A method in accordance with  claim 1 , wherein the step of bundling further includes the step of:
 stacking the plurality of buoyancy joints in a stacked configuration with each buoyancy joint in a horizontal orientation.   
   
   
       3 . A method in accordance with  claim 1 , wherein the step of transporting further includes the step of:
 disposing the plurality of buoyancy joints in the bundled configuration on a deck of a barge or a deck boat.   
   
   
       4 . A method in accordance with  claim 1 , wherein the step of disposing further includes the step of:
 engaging lift-eyes in the external frames of the buoyancy joints with hooks;   lifting the buoyancy joints with the hooks; and   positioning the buoyancy joints for coupling along the riser system.   
   
   
       5 . A method in accordance with  claim 1 , wherein the step of providing a plurality of buoyancy joints, further comprises providing a plurality of buoyancy joints each comprising:
 a) a riser section;   b) a vessel, directly coupled to the riser section, configured to be pressurized with gas;   c) the external frame disposed around the vessel;   d) an enclosure, associated with the external frame and substantially enclosing the vessel, defining a space between the enclosure and the vessel; and   e) a buoyant cladding, disposed in the space between the vessel and the enclosure.   
   
   
       6 . A method in accordance with  claim 5 , wherein the enclosure includes a plurality of flat panels forming a rectilinear box. 
   
   
       7 . A method in accordance with  claim 6 , wherein the flat panels include fiber reinforced plastic. 
   
   
       8 . A method in accordance with  claim 5 , wherein each of the plurality of buoyancy joints has a vessel with a diameter or length that is different from respective diameters or lengths of vessels of other buoyancy joints associated with the riser system. 
   
   
       9 . A method in accordance with  claim 5 , wherein the enclosure forms a mold configured to receive an uncured foam material therein to form the buoyant cladding. 
   
   
       10 . A method in accordance with  claim 5 , wherein:
 the vessel includes a fiber reinforced plastic;   the buoyant cladding includes rigid foam; and   the enclosure includes a fiber reinforced plastic.   
   
   
       11 . A method in accordance with  claim 5 , wherein the buoyant cladding includes rigid foam substantially filling the space between the vessel and the enclosure. 
   
   
       12 . A method in accordance with  claim 5 , wherein the vessel fills a majority of a volume defined by the external frame, and the cladding fills a minority of the volume with respect to the vessel. 
   
   
       13 . A method in accordance with  claim 5 , wherein the vessel has an outer diameter that substantially equals an inner diameter of the enclosure. 
   
   
       14 . A method in accordance with  claim 5 , wherein the cross-sectional shape is selected from the group consisting of: square, rectangular, triangular, pentagonal, hexagonal, and octagonal. 
   
   
       15 . A method in accordance with  claim 5 , wherein the vessel has a substantially circular cross-sectional shape with respect to the longitudinal axis. 
   
   
       16 . A method in accordance with  claim 5 , wherein the vessel includes opposite, spaced-apart, hemispherical domes, each having an aperture through which the riser section extends, and seals formed between the riser section and the domes. 
   
   
       17 . A method in accordance with  claim 5 , wherein the external frame includes:
 a pair of spaced apart end caps having an outer perimeter orthogonal to a longitudinal axis shaped with at least three linear sides;   longitudinal members, extending between the end caps; and   lateral members, extending between the riser section and the outer perimeter.   
   
   
       18 . A method in accordance with  claim 5 , wherein the external frame includes:
 means for intercoupling the external frame with other external frames of other buoyancy joints bundled together.   
   
   
       19 . A method in accordance with  claim 5 , further comprising means for joining the riser section to other riser sections. 
   
   
       20 . A method in accordance with  claim 5 , further comprising a pressurization tube extending into the vessel for pressuring the vessel. 
   
   
       21 . A method for fabricating a buoyancy joint for a riser of an offshore platform, comprising the steps of:
 a) providing a vessel with opposite apertures at opposite longitudinal ends capable of receiving a riser section therethrough, and an enclosure formed substantially around the vessel; and   b) injecting foam into the enclosure to substantially fill space between the vessel and the enclosure.   
   
   
       22 . A method in accordance with  claim 21 , wherein step a) further includes the steps of:
 a) disposing the vessel about the riser section and forming a frame around the vessel; and   b) forming the enclosure around the vessel.   
   
   
       23 . A method in accordance with  claim 21 , further comprising the step of:
 forming the vessel with a fiber reinforced plastic and overwrapping the vessel with fiber reinforcement.