Offshore storage system

Claim 2

In combination, an offshore storage tank supported by a sea floor comprising: a circular cylindrical vertical metal shell; a continuous horizontal rigid bottom containing solid ballast, joined to the shell and resting on the sea floor; said vertical metal shell extending from the rigid bottom upwardly to above sea level for a height adequate for the shell to hold liquid to a liquid level above the level of the sea surrounding the tank to provide a pressure together with the pressure of the tank weight, which is adequate to hold the tank in place on the sea floor during storm conditions; said vertical shell only when supplemented by said internal liquid pressure being able to withstand storm conditions without buckling and collapsing with the tank resting on the sea floor; and liquid in the shell to a level above the surrounding sea which is adequate to hold the tank in place on the sea floor during storm conditions without buckling and collapsing.

Claim 3

A combination according to claim 1 in which the tank is covered by a fixed-position roof supported above sea level by the vertical metal shell.

Claim 4

In combination, an offshore storage tank supported by a sea floor comprising: a circular cylindrical vertical metal shell; a continuous horizontal rigid bottom containing solid ballast, joined to the shell and resting on the sea floor; said vertical shell extending from the rigid bottom upwardly to above sea level for a height adequate for the shell to hold a liquid to a liquid level above the level of the sea surrounding the tank to provide a pressure together with the pressure of the tank weight, which is adequate to hold the tank in place on the sea floor during storm conditions; said vertical shell only when supplemented by said internal liquid pressure being able to withstand storm conditions without buckling and collapsing with the tank resting on the sea floor; means for supplying a liquid hydrocarbon to, and for withdrawing it from, the tank, and means for supplying water to the tank and withdrawing it therefrom; said means for supplying a liquid hydrocarbon to, and withdrawing it from, the tank and said means for supplying water to, and withdrawing water from, the tank being operable to maintain a total liquid content in the tank which exerts a pressure on the tank bottom per unit area greater than the external sea pressure; and liquid in the shell to a level above the surrounding sea which is adequate to hold the tank in place on the sea floor during storm conditions without buckling and collapsing.

Claim 5

In combination, an offshore storage tank supported by a sea floor comprising: a circular cylindrical vertical metal shell; a continuous horizontal rigid bottom containing solid ballast, joined to the shell and resting on the sea floor; said vertical shell extending from the rigid bottom upwardly to above sea level for a height adequate for the shell to hold a liquid to a liquid level above the level of the sea surrounding the tank to provide a pressure together with the pressure of the tank weight, which is adequate to hold the tank in place on the sea floor during storm conditions; said vertical shell only when supplemented by said internal liquid pressure being able to withstand storm conditions without buckling and collapsing with the tank resting on the sea floor; means for supplying a liquid hydrocarbon to, and for withdrawing it from, the tank, and means for supplying water to the tank and withdrawing it therefrom; said means for supplying a liquid hydrocarbon to, and withdrawing it from, the tank and said means for supplying water to, and withdrawing water from, the tank being operable to maintain a total liquid content in the tank which exerts a pressure on the tank bottom per unit area greater than the external sea pressure; and liquid in the shell to a level above the surrounding sea which is adequate to hold the tank in place on the sea floor during storm conditions without buckling and collapsing.

Claim 6

A combination according to claim 3 in which the bottom comprises a metal plate on top of which is a substantially uniform layer of concrete.

Claim 7

A combination according to claim 4 in which a metal plate is located on top of the concrete layer and is joined to the vertical shell.

Claim 8

A combination according to claim 3 in which a metal skirt extends vertically downwardly from the tank bottom.

Claim 9

A combination according to claim 3 in which the means for withdrawing water from the tank includes a conduit inlet communicating with the bottom interior space of the tank and an outlet located at the height of the maximum water level wHich the tank is calculated to hold.

Claim 10

A combination according to claim 3 in which the means for withdrawing liquid hydrocarbon from the tank includes a conduit having an inlet in the tank at the height of the maximum water level which the tank is calculated to hold.

Claim 11

An offshore storage tank comprising: a circular cylindrical vertical metal shell made of horizontal metal rings with the rings of the shell subject to wave action thicker than the other rings in the vertical metal shell; a continuous horizontal rigid bottom comprising solid ballast, joined to the shell and adapted to rest on a sea floor; said vertical shell being tall enough to project above sea level, when the bottom is on the sea floor, for a height adequate for the shell to hold, when full, a liquid to a liquid level above sea level to provide a pressure together with the pressure of the tank weight, adequate to hold the tank in place during storm conditions at a locality where the tank is to be positioned; and said vertical shell only when supplemented by said internal liquid pressure being able to withstand storm conditions without collapsing when the tank rests on the sea floor.

Claim 12

An offshore storage tank comprising: a circular cylindrical vertical metal shell made of horizontal metal rings with the rings of the shell subject to wave action thicker than the other rings in the vertical metal shell; a continuous horizontal rigid bottom comprising solid ballast, joined to the shell and adapted to rest on a sea floor; said vertical shell being tall enough to project above sea level, when the bottom is on the sea floor, for a height adequate for the shell to hold, when full, a liquid to a liquid level above sea level to provide a pressure together with the pressure of the tank weight, adequate to hold the tank in place during storm conditions at a locality where the tank is to be positioned; and said vertical shell only when supplemented by said internal liquid pressure being able to withstand storm conditions without collapsing when the tank rests on the sea floor.

Claim 13

An offshore storage tank comprising: a circular cylindrical vertical metal shell having a plurality of horizontal spaced-apart stiffener rings joined to the internal surface thereof; said vertical metal shell having a cylindrical metal roof-guiding shell inside the upper portion thereof over the stiffeners adjacent thereto and the cylindrical metal roof-guiding shell has a height from maximum water level to maximum oil level in the tank; a floating roof having a periphery in close proximity to the cylindrical metal roof-guiding shell internal surface; a continuous horizontal rigid bottom containing solid ballast, joined to the shell and adapted to rest on a sea floor; said vertical shell being tall enough to project above sea level, when the bottom is on the sea floor, for a height adequate for the shell to hold, when full, a liquid to a liquid level above sea level to provide a pressure together with the pressure of the tank weight, adequate to hold the tank in place during storm conditions at a locality where the tank is to be positioned; and said vertical shell only when supplemented by said internal liquid pressure being able to withstand storm conditions without collapsing when the tank rests on the sea floor.

Claim 14

An offshore storage tank comprising: a circular cylindrical vertical metal shell having a plurality of horizontal spaced-apart stiffener rings joined to the internal surface thereof; said vertical metal shell having a cylindrical metal roof-guiding shell inside the upper portion thereof over the stiffeners adjacent thereto and the cylindrical metal roof-guiding shell has a height from maximum water level to maximum oil level in the tank; a floating roof having a periphery in close proximity to the cylindrical metal roof-guiding shell internal surface; a continuous horizontal rigid bottom containing solid ballast, joined to the shell and adapted to rest on a sea floor; said vertical shell being tall enough to project above sea level, when the bottom is on the sea floor, for a height adequate for the shell to hold, when full, a liquid to a liquid level above sea level to provide a pressure together with the pressure of the tank weight, adequate to hold the tank in place during storm conditions at a locality where the tank is to be positioned; and said vertical shell only when supplemented by said internal liquid pressure being able to withstand storm conditions without collapsing when the tank rests on the sea floor.