Offshore platform structures

Claim 1

A method of constructing an offshore platform structure on a selected site on the sea floor, comprising: transporting to the site at least one center column having a length which is greater than the depth of the bodY of water at said site; transporting to said site at least three batter columns, the central column and each batter column having a multi-legged structure consisting of at least three legs, each leg having an upper end, a lower end, and each batter column having a length which is considerably greater than the length of said center column; erecting the center column on a selected area within said site whereby its upper end extends above the water surface; securing the lower end of said center column to said floor; erecting the batter columns around said center column, welding the upper ends of the batter columns to angularly spaced portions about the upper end of the center column above the water surface and fixedly securing their lower ends to said floor in bracing relation to said center column and to each other thereby forming a support structure; driving piles through the entire length of certain ones of the legs in each column to thereby fixedly secure each column to the sea floor, whereby the axial load on each pile resists a substantial portion of the lateral load on said support structure; and framing a working platform onto the erected support structure.

Claim 2

A method of constructing an offshore platform structure on a selected site on the sea floor, comprising: transporting to the site at least one center column having a length which is greater than the depth of the bodY of water at said site; transporting to said site at least three batter columns, the central column and each batter column having a multi-legged structure consisting of at least three legs, each leg having an upper end, a lower end, and each batter column having a length which is considerably greater than the length of said center column; erecting the center column on a selected area within said site whereby its upper end extends above the water surface; securing the lower end of said center column to said floor; erecting the batter columns around said center column, welding the upper ends of the batter columns to angularly spaced portions about the upper end of the center column above the water surface and fixedly securing their lower ends to said floor in bracing relation to said center column and to each other thereby forming a support structure; driving piles through the entire length of certain ones of the legs in each column to thereby fixedly secure each column to the sea floor, whereby the axial load on each pile resists a substantial portion of the lateral load on said support structure; and framing a working platform onto the erected support structure.

Claim 5

A method of constructing an offshore platform structure positioned in a body of water and extending from the bottom thereof to support a working platform above the water''s surface, comprising: erecting a vertical center column in the body of water having pivot means at angularly spaced apart points on the upper end of said column; pivotally securing a plurality of batter columns to said pivot means while maintaining said batter columns in a substantially horizontal position, each batter column having a multi-legged structure consisting of at least three legs, each leg having an upper end, a lower end, and a length which is considerably greater than the length of said center column; controllably ballasting the batter columns until their lower ends land on the marine bottom; affixing the lower ends of all batter columns to the marine bottom in bracing relation to the center column and to each other, whereby said center column and said batter columns form a support structure; driving piles through the entire length of certain ones of the legs in each batter column to thereby fixedly secure each column to the sea floor, whereby the axial load on each pile resists a substantial portion of the lateral load on said platform structure; and framing onto said support structure a working platform.

Claim 6

A method of constructing an offshore platform structure positioned in a body of water and extending from the bottom thereof to support a working platform above the water''s surface, comprising: erecting a vertical center column in the body of water having pivot means at angularly spaced apart points on the upper end of said column; pivotally securing a plurality of batter columns to said pivot means while maintaining said batter columns in a substantially horizontal position, each batter column having a multi-legged structure consisting of at least three legs, each leg having an upper end, a lower end, and a length which is considerably greater than the length of said center column; controllably ballasting the batter columns until their lower ends land on the marine bottom; affixing the lower ends of all batter columns to the marine bottom in bracing relation to the center column and to each other, whereby said center column and said batter columns form a support structure; driving piles through the entire length of certain ones of the legs in each batter column to thereby fixedly secure each column to the sea floor, whereby the axial load on each pile resists a substantial portion of the lateral load on said platform structure; and framing onto said support structure a working platform.

Claim 9

A method of constructing an offshore platform structure extending over a selected site on the sea floor, comprising: transporting to and erecting on said site a central column having a length which is greater than three hundred feet; transporting to said site at least three batter columns, each batter column having a multi-legged structure consisting of at least three legs, each leg having an upper end, a lower end, and a length which is considerably greater than the central column; uprighting each batter column by pivotally securing it above the water surface to the upper end of the central column and by ballasting its lower end, whereby the lower ends of said batter columns are widely spaced apart; grounding the lower end of each uprighted batter column; welding above the water surface the upper ends of said batter columns to said center column; driving piles through the entire length of certain ones of the legs in each batter column to thereby fixedly secure each column to the sea floor, whereby the axial load on each pile resists a substantial portion of the lateral load on said platform structure; lowering a transition structure having a plurality of legs over the welded upper ends of said columns; welding the legs of said transition structure to the welded upper ends of said columns; and framing a working platform onto said transition structure.

Claim 10

A method of constructing an offshore platform structure extending over a selected site on the sea floor, comprising: transporting to and erecting on said site a central column having a length which is greater than three hundred feet; transporting to said site at least three batter columns, each batter column having a multi-legged structure consisting of at least three legs, each leg having an upper end, a lower end, and a length which is considerably greater than the central column; uprighting each batter column by pivotally securing it above the water surface to the upper end of the central column and by ballasting its lower end, whereby the lower ends of said batter columns are widely spaced apart; grounding the lower end of each uprighted batter column; welding above the water surface the upper ends of said batter columns to said center column; driving piles through the entire length of certain ones of the legs in each batter column to thereby fixedly secure each column to the sea floor, whereby the axial load on each pile resists a substantial portion of the lateral load on said platform structure; lowering a transition structure having a plurality of legs over the welded upper ends of said columns; welding the legs of said transition structure to the welded upper ends of said columns; and framing a working platform onto said transition structure.