Column-stabilized offshore vessel

Abstract

The invention relates to a semi-submersible vessel designed to operate in water depths of 200 to 10,000 feet. The vessel has a ring pontoon with an outer and inner configuration of the pontoon forming a triangle. Three corner columns are fixedly attached at their lower ends to the ring pontoon. The upper ends of the stabilizing columns carry an upper deck designed to support drilling and production operations. The vessel uses no diagonal or horizontal braces, nor auxiliary supporting columns. The triangular shape of the vessel minimizes environmental forces acting on the vessel, thus improving its stability at any operational draft. The vessel can be fully constructed and outfitted quay (dock) side.

We claim:  
     
         1 . A semi-submersible vessel, comprising: 
 a buoyant generally triangularly-shaped pontoon;    a plurality of vertical stabilizing columns fixedly attached to said pontoon, each column having an intercostal connection with a respective corner of said pontoon; and    a platform supported by upper ends of said columns for conducting offshore operations therefrom.    
     
     
         2 . The vessel of  claim 1 , wherein said pontoon is a ring pontoon.  
     
     
         3 . The vessel of  claim 2 , wherein an outer perimeter of said ring pontoon forms a triangle.  
     
     
         4 . The vessel of  claim 2 , wherein an inner perimeter of said ring pontoon forms a triangle.  
     
     
         5 . The vessel of  claim 1 , where said pontoon comprises a plurality of pontoon sections, each end of each pontoon section being fixedly attached to an adjoining pontoon section and to at least one of said stabilizing columns.  
     
     
         6 . The vessel of  claim 5 , wherein each of said columns is attached to said pontoon along at least one side.  
     
     
         7 . The vessel of  claim 5 , wherein each of said pontoon section has a generally rectangular cross section.  
     
     
         8 . The vessel of  claim 1 , wherein each of said stabilizing columns has a generally square cross-section, and wherein outer corners of each of said stabilizing columns is outwardly convex to reduce drag forces acting on the vessel.  
     
     
         9 . A semi-submersible vessel, comprising: 
 a buoyant ring pontoon having an outer perimeter defining a triangle;    a plurality of vertical stabilizing columns fixedly attached to said pontoon, each column being connected along at least one side to an intersecting corner of the ring pontoon sides; and    a platform supported by upper ends of said columns for conducting offshore operations therefrom.    
     
     
         10 . The vessel of  claim 9 , wherein the ring pontoon has a non-continuous connection to each of said stabilizing columns.  
     
     
         11 . The vessel of  claim 9 , where said pontoon comprises a plurality of pontoon sections, each end of each pontoon section being fixedly attached to an adjoining pontoon section and to at least one of said stabilizing columns.  
     
     
         12 . The vessel of  claim 9 , wherein an inner perimeter of said ring pontoon forms a triangle.  
     
     
         13 . The vessel of  claim 9 , wherein each of said stabilizing columns has a generally square cross-section, and wherein outer corners of each of said stabilizing columns are outwardly convex to reduce drag forces acting on the vessel.  
     
     
         14 . The vessel of  claim 11 , wherein each of said pontoon sections has a generally rectangular cross-section.  
     
     
         15 . The vessel of  claim 9 , wherein each of said columns is attached to said pontoon along at least one side.  
     
     
         16 . The vessel of  claim 9 , wherein each of said columns is attached to said pontoon along more than one side.