Installation of vertically moored platforms

A method of installing a Vertically Moored Platform at a selected site, said platform having four buoyant legs positioned in a rectangular pattern which comprises:

• a. setting each buoyant leg on a section of a gravity base, the total buoyancy of the gravity base being sufficient to support said platform in water;
• b. positioning riser spacers on top of said gravity base;
• c. towing the platform and gravity base to the selected well site;
• d. reducing the buoyancy of two adjacent gravity base sections until the platform is tilted toward said two gravity base sections;
• e. thereafter reducing the buoyancy of all sections until the center line of the platform is vertical;
• then simultaneously reducing the buoyancy of each gravity base section until all buoyancy of each gravity base section has been removed and has a submerged weight;
• f. then partially flooding the buoyant legs until an operating draft has been reached;
• and
• g. thereafter lowering the gravity base to the bottom of th body of water while simultaneously lowering said riser spacers into position and securing anchor elongated members between each lowered gravity base section and its respective buoyant leg.

A method of installing a Vertically Moored Platform at a selected site in water, said platform having at least three buoyant legs positioned in a geometrical pattern which comprises:

• a. setting each buoyant leg on one of a plurality of buoyant sections of a gravity base, the total buoyancy of the gravity base being sufficient to support said platform in water;
• b. towing the platform and gravity base to the selected well site;
• c. reducing the buoyancy of at least one gravity base section until the platform is tilted toward said at least one gravity base section while maintaining said gravity base in a buoyant condition completely above the bottom of said water;
• d. thereafter and while said gravity base is still completely above bottom reducing the buoyancy of all sections until the center line of the platform is vertical;
• then simultaneously reducing the buoyancy of each said gravity base section in a manner to maintain the center line of the platform vertical until all buoyancy of each gravity base section has been removed and has a submerged weight;
• e. then partially flooding the buoyant legs until an operating draft has been reached;
• and
• f. thereafter lowering the gravity base of the bottom of the body of water and securing anchor elonated members between each lowered gravity base section and its respective buoyant leg.