Offshore platform for hydrocarbon production and storage

Abstract

In a floating structure, a ballast weight is suspended at a truss angle from an upper section of the floating structure using at least three tension members. This ballast weight is suspended at such a depth and in such a manner that the center of gravity of the floating structure is below the center of buoyancy of the floating structure. The suspension of the ballast weight allows the floating structure to maintain greater stability and achieve desirable motions in response to environmental conditions such as wind and waves.

What is claimed:  
     
         1 . A floating structure, comprising: 
 a buoyant upper section which includes at least one vertical column arranged and designed at its upper most end to support at least one deck for offshore hydrocarbon operations;    a lower section including a ballast weight suspended beneath said upper section, wherein said ballast weight is suspended at a depth such that a center of gravity of said floating structure is below a center of buoyancy of said floating structure, said lower section further including: 
 at least three tension members which connect said ballast weight to said upper section, wherein at least three of said tension members in connecting said upper section to said ballast weight are arranged to form truss angles in at least two non-coplanar planes, and wherein said truss angles are arranged and designed to prevent any of said tension members to go slack, allowing said floating structure to act like a rigid body.  
   
     
     
         2 . The floating structure of  claim 1 , wherein at least one of vertical column of said upper section is buoyant.  
     
     
         3 . The floating structure of  claim 2 , wherein the floating structure includes a broad base at an underwater location.  
     
     
         4 . The floating structure of  claim 3 , wherein said ballast weight is at least one distributed mass with and opening disposed through it, and said floating structure is moored via a mooring means.  
     
     
         5 . The floating structure of  claim 3 , wherein said ballast weight is at least one concentrated mass, wherein the floating structure is moored via a mooring means.  
     
     
         6 . The floating structure of  claim 1 , wherein said floating structure includes a buoyant broad base at an underwater location.  
     
     
         7 . The floating structure of  claim 6 , wherein said ballast weight is at least one distributed mass with and opening disposed through it, and wherein said floating structure is moored via a mooring means.  
     
     
         8 . The floating structure of  claim 6 , wherein said ballast weight is at least one concentrated mass, and wherein said floating structure is moored via a mooring means.  
     
     
         9 . A method for providing static stability to a floating structure comprising step of: 
 suspending a ballast weight below an upper section of said floating structure via at least three tension members, wherein said ballast weight is at a depth such that a center of gravity for said floating structure is below a center of buoyancy for said floating structure; and    trussing at least three of said tension members between the connection of the upper section to the ballast weight in at least two non-coplanar planes, wherein the truss angles are arranged and designed to prevent any of said tension members to go slack, allowing said floating structure to act like a rigid body.    
     
     
         10 . The method of  claim 9 , further comprising the step of: 
 minimizing heave motions on the floating structure via the use of a broad base as part of said upper section.    
     
     
         11 . The method of  claim 10 , wherein the floating structures has a single, small waterplane area.  
     
     
         12 . A method of installing a floating structure comprising the steps of: 
 towing an upper section of the floating structure on site while floating the upper section on a broad base of the upper section;    deploying a ballast weight from the upper the broad base to lower the center of gravity of the floating structure to a depth below the center of buoyancy of the floating structure; and    ballasting the base to a desired equilibrium of floatation.