An offshore drilling and production apparatus (20) in which an upper buoyant hull (24) of prismatic shape has a passage (38) longitudinally extending through the hull in which risers (42) extend to the sea floor, the hull bottom (24) located at a depth dependent upon the wind, wave, and current environment at the site, which reduces the wave forces acting on the hull bottom (24), a frame structure (26) connected to the hull bottom and extending downwardly and comprising a plurality of vertical bays (50) defined by horizontal water entrapment plates (52) and providing windows (56) around the periphery of the frame structure, the windows providing transparency in a horizontal direction to reduce drag, the vertical space between the plates (52) corresponding to the width of the bay window (56), the frame structure (26) being below significant wave action whereby wave action thereat inhibits heave motion, the frame structure (26) modifies the natural period and stability of the apparatus (20) to minimize heave, pitch, and roll motions

Deep water offshore apparatus

A submersible/semi-submersible dry lift carrier for transporting a jack-up drilling rig in a body of water includes a hull, a deck, at least one stability column, and a plurality of ballast compartments capable of being flooded and emptied for lowering and raising the carrier The carrier further includes at least three leg wells, each well sized and spaced for receiving a leg from a jack-up drilling rig, and each of said wells comprising a vertical passageway having a first end opening through the deck and a second end opening through the bottom of the hull The carrier further includes at least three pinning receptacles, each receptacle sized and spaced for receiving a spud can and leg from a jack-up drilling rig In operation, the dry lift carrier is partially submerged by flooding the ballast compartments and then positioned beneath the floating jack-up rig The carrier is de-ballasted thereby lifting the jack-up rig from a floating "wet" mode to a "dry" mode on the deck of the carrier Alternatively, the dry lift carrier is submerged and rests on the floor of the body of water The floating jack-up rig is positioned over the dry lift carrier The carrier is de-ballasted thereby lifting the jack-up rig on the deck of the carrier

Submersible and semi-submersible dry lift carrier and method of operation for carrying a drilling rig and platform

A concrete barge having oil storage tanks secured to its deck is towed to an oil production site where it is sunk to the sea bottom. Oil from an adjacent caisson supported production facility is temporarily stored in the tanks pending later transfer to an oil tanker. The caisson may be braced from the barge in hard-bottomed locations or may be guyed to the sea floor. Compartments in the concrete barge are filled with water as required for ballast and trim while the barged is being towed to location. The compartments are flooded with seawater to provide the sinking force to carry the barge and tank assembly to the sea bottom and hold the assembly on the sea bottom. Descent of the barge from the surface to the sea bottom is regulated by controlling the placement and pressure of air in the storage tanks. The submerged barge and tanks are filled with seawater to prevent hydrostatically induced crushing pressure differentials. Oil added to the tanks from the production facility displaces an equal volume of seawater from the tanks to ensure that the tanks remain constantly filled with a fluid. Oil is displaced from the tanks to the tanker by the introduction of seawater into the tank bottoms. The outlet from the tanks is taken from the tank tops so that the lighter oil is discharged into the sales lines as the heavier water occupies an increasing volume in the lower level of the tank. The tanks are coated in concrete to increase their collapse resistance.

Offshore production and storage facility and method of installing the same

An offshore drilling structure of the semi-submersible type wherein holes connect a recessed area in the bottom of the floatable hull with the top of the hull, and reversibly acting thrusters are mounted within the holes.

Offshore drilling structure

In the erection of offshore structures, preferred method steps including releasably securing a vessel adapted for water navigation to a structure, said structure being adapted to be stabilized at selected locations of various depths wherein stabilization enables mineral-related, military, and transportation apparatus to function from said structure, altering the elevation of the vessel with respect to the structure whereby the vessel is made more free of wave action at the altered elevation and thereafter restoring the vessel to a navigable relationship to the body of water; said invention including apparatus for supporting a separable structure wherein the support immediately below the structure is designed principally with support of the structure in view and extends downwardly to a footing member, wherein support members below said footing member are founded in the soil beneath the body of water and are designed principally as foundation members.

Method and apparatus for offshore operations

Mobile marine platform apparatus

904,126 Submerged tanks BETHLEHEM STEEL CO Oct 19, 1960 [Oct 23, 1959], No 35816/60 Class 68 (2) A marine oil storage apparatus comprises a hull 1 which may be submerged on to the sea bed and which is divided into a number of separate compartments, eg 7, 10, 11, 12 Four columns 13 are secured to the hull, one at each corner, which extend above the surface of the surrounding water Oil is received in the tank battery 19 and may be passed to the compartments 7, 10, 11, 12 to displace the water already in the compartments up to the receiver 42 to overflow into the surrounding water Oil from storage may be passed to a tanker directly from the tanks 19 or it may be displaced from the submerged compartments into the lines 43, 44, 49, 50 by pumping water into the receiver 42 so that it passes to the compartment through lines 63 to 68 The apparatus may be refloated by using compressed air

Offshore storage unit

A method and apparatus for removing and/or adding column sections to a column of a marine structure, such as a mobile drilling platform, employs a carriage for supporting a column section slidably mounted on the marine structure platform and jacking means for moving the platform and column relative to each other. When a column section is to be added to the column, the carriage with a column section supported thereon is positioned above the column. The jacking means is then operated to bring the top of the column into contact with the bottom of the carriage supported column section. The column section is then welded to the column and detached from the carriage. When a column section is to be removed from the column, a carriage is positioned above the column. The jacking means is then operated to bring the column within the carriage, and the column is secured to the carriage. A portion of the column is then severed from the column.

John C Estes

Papers

Mobile marine platform apparatus

Offshore storage unit

Apparatus and method for removing and/or adding column sections to a column of a marine structure

Fluid tight shield