Floating platform for offshore drilling or production of hydrocarbons

Abstract

A floating platform for offshore drilling or production of hydrocarbons comprises a topsides with drilling and/or production equipment ( 8 ), and a substructure comprising a lower pontoon ( 3 ) and columns ( 4 ) connecting the pontoon ( 3 ) to the topsides ( 1 ). During its operation the platform is exposed to wave forces ( 9 ) which cause heave motion (v) and roll and pitch motion (p) of the platform. The substructure has a draught ( 11 ) which is at least 40 metres, preferably at least 50 metres and most preferred at least 60 metres, and the ratio between the distance ( 16 ) between the columns' centre axes ( 25 ), measured along a side of the substructure, and the lower substructure's draught ( 11 ) is between 1.0 and 1.5, preferably between 1.2 and 1.4 and most preferred between 1.3 and 1.35.

1 . A floating platform for offshore drilling or production of hydrocarbons, comprising a topsides with drilling and/or production equipment ( 8 ), and a substructure comprising a lower pontoon ( 3 ) and columns ( 4 ) connecting the pontoon ( 3 ) to the topsides ( 1 ), where during its operation the platform is exposed to wave forces ( 9 ) which cause heave motion (v) and roll and pitch motion (p) of the platform,  
       characterized in that 
 a) the substructure has a draught ( 11 ) which is at least 40 metres, preferably at least 50 metres and most preferred at least 60 metres, and  
 b) the ratio of the substructure's draught ( 11 ) to the distance ( 16 ) between the columns' centre axes ( 25 ), measured along a side of the substructure is between 1.0 and 1.5, preferably between 1.2 and 1.4 and most preferred between 1.3 and 1.35.  
 
     
     
         2 . A floating platform according to  claim 1 ,  
       characterized in that the weight of the topsides ( 1 ), the design, displacement, number and position of the columns ( 4 ) and the design and displacement of the pontoon ( 3 ) are adapted so as to give the platform a natural period (t z ) for heave motion which is at least 22, preferably at least 24 and most preferred at least 26 seconds.  
     
     
         3 . A floating platform according to  claim 1  or  2 ,  
       characterized in that the ratio of total cross sectional area of the columns ( 4 ) in the waterline ( 10 ) to the platform's total mass is between 0.005 and 0.018 m 2 /metric ton, and preferably between 0.08 and 0.015 m 2 /metric ton.