Abstract: A method for developing an offshore field comprises (a) coupling a plurality of top-tensioned risers to a first vessel at a first location. In addition, the method comprises (b) decoupling the first vessel from the plurality of top-tensioned risers after (a). Further, the method comprises (c) coupling a second vessel to the plurality of top-tensioned risers after (b) at the first location.

Abstract: An offshore structure comprises a hull having a longitudinal axis and including a first column and a second column moveably coupled to the first column. Each column has a longitudinal axis, a first end, and a second end opposite the first end. In addition, the offshore structure comprises an anchor coupled to the second end of the second column and configured to secure the hull to the sea floor. The first column includes a variable ballast chamber and a first buoyant chamber positioned between the variable ballast chamber and the first end of the first column. The first buoyant chamber is filled with a gas and sealed from the surrounding environment. The second column includes a variable ballast chamber. Further, the offshore structure comprises a topside mounted to the hull.

Abstract: An offshore structure comprises a hull having a longitudinal axis, a first end, and a second end opposite the first end. In addition, the structure comprises an anchor coupled to the lower end of the hull and configured to secure the hull to the sea floor. The anchor has an aspect ratio less than 3:1. The hull includes a variable ballast chamber positioned axially between the first end and the second end of the hull and a first buoyant chamber positioned between the variable ballast chamber and the first end of the hull. The first buoyant chamber is filled with a gas and sealed from the surrounding environment. Further, the structure comprises a ballast control conduit in fluid communication with the variable ballast chamber and configured to supply a gas to the variable ballast chamber. The structure also comprises a topside mounted to the first end of the hull.

Abstract: Methods for developing an offshore field comprising deploying a lead drilling and production vessel to a offshore field to drill and complete at least one well. Production from the at least one well is initiated and evaluated. A secondary production vessel is selected based upon the evaluated production and is deployed to the offshore field to replace the lead drilling and production vessel and support production of the at least one well.

Abstract: A system for offloading a fluid from an offshore structure comprises an annular conduit support structure disposed about the offshore structure. The support structure is fixably coupled to the offshore structure. In addition, the system comprises an annular reel disposed about the offshore structure and rotatably coupled to the support structure. The reel includes a conduit fairlead configured to move relative to the support structure. Further, the system comprises a flexible conduit having a fluid inlet end and a fluid outlet end. The flexible conduit includes a first portion wrapped around the conduit support structure and a second portion extending from the conduit support structure through the fairlead.

Abstract: A platform for offshore drilling and/or production operations comprises an equipment deck. In addition, the platform comprises a buoyant hull coupled to the equipment deck and configured to extend below the surface of the water. The hull comprises a first column having a central axis, an upper end coupled to the deck, a lower end distal the deck, and a plurality of axially stacked cells between the upper end and the lower end. Each cell defining an inner chamber within the cell and an exterior region outside the cell. The plurality of cells includes a first cell extending from the upper end of the first sub-column and a second cell axially positioned below the first cell. The first cell is water-tight. Further, the second cell includes a gas port configured to supply a buoyancy control gas to the inner chamber of the second cell.

Abstract: A floating oil storage system and associated methods for storing oil are disclosed. In some embodiments, the floating oil storage system includes a storage cell, a floating member disposed within the storage cell, whereby the storage cell is divided into a first compartment and a second compartment disposed below the first compartment, a pump operable to deliver oil under pressure into the first compartment, whereby the first compartment expands and the second compartment contracts expelling seawater from the second compartment, and a suction tank operable to receive oil expelled from the first compartment under hydrostatic pressure of seawater in the second compartment, whereby the first compartment contracts and the second compartment expands receiving seawater.

Abstract: A method for storing a gas. In some embodiments, the method includes positioning a gas storage system under water, the gas storage system having a gas inlet and injecting gas through the gas inlet into the gas storage system, wherein the gas is compressed. The method may further include venting the compressed gas through the at least one gas port to a storage facility.

Abstract: Production systems and associated methods are disclosed. In some embodiments, the production system includes a production barge and a production facility disposed on the production barge. The production facility is operable to produce a plurality of modular components for use in construction of an offshore structure, wherein the modular components comprise at least one of a stiffened plate and a stiffened tubular.

Abstract: A floating oil storage system and associated methods for storing oil are disclosed. In some embodiments, the floating oil storage system includes a storage cell, a floating member disposed within the storage cell, whereby the storage cell is divided into a first compartment and a second compartment disposed below the first compartment, a pump operable to deliver oil under pressure into the first compartment, whereby the first compartment expands and the second compartment contracts expelling seawater from the second compartment, and a suction tank operable to receive oil expelled from the first compartment under hydrostatic pressure of seawater in the second compartment, whereby the first compartment contracts and the second compartment expands receiving seawater.

Abstract: A configurable, multi-function vessel that comprises first and second pontoon barges and a plurality of interconnecting barges. The first and second pontoon barges have a plurality of connection members disposed on the inboard sides thereof. The plurality of interconnecting barges are disposable between the inboard sides of the first and second pontoon barges so that a plurality of connection members disposed on opposite sides of the interconnecting barges are adjacent to the connection members on either said first or second pontoon barge. A plurality of connectors releasably couple adjacent connection members so that the pontoon barges and the interconnecting barges form a unitary, oceangoing vessel.

Abstract: A deep ocean gas storage system for storing compressed gas, the system comprising an inflexible thin walled storage vessel anchored to the sea floor having an axis located in water substantially perpendicular to and on a sea floor below sea level, a gas intake for admitting and discharging compressed natural gas to and from the vessel; a water port for admitting and discharging water to the vessel using hydrostatic pressure to discharge compressed gas from the vessel at a substantially constant discharge pressure as the volume of the gas in the storage vessel decreases when water content of the vessel increases; a conduit fluidly connected with the water port oriented substantially parallel to the axis having a discharge opening above the level of sea water in the vessel; and a valve disposed at the gas intake to the vessel for controlling compressed gas admission and discharge.

Abstract: A method for making a deep draft semi-submersible drilling/production vessel having a center of gravity below its center of buoyancy by constructing a plurality of buoyant individual columns. The method connects a pair of columns with at least a first top truss and a first bottom truss. The method additionally floats a connected first and second columns horizontally in water. The method floats the semi-submersible structure to a location for installation. The method concludes by deballasting the semi-submersible structure with connected deck forming a semi submersible drilling/production vessel having a center of gravity below its center of buoyancy with a draft between 300 and 500 feet.

Abstract: Systems and methods for coupling a topside to a fixed or floating substructure during float-over installation of the topside are disclosed. Some system embodiments include a first plate coupled to a leg of the substructure and a retaining wall coupled to the first plate and extending substantially normally therefrom, wherein the retaining wall and the first plate form a recess. The system embodiments further include a second plate disposed at an end of a leg of the topside, the second plate received within the recess and engaging the first plate, and a plurality of shims disposed between the second plate and the retaining wall, wherein the plurality of shims are configured to inhibit translational movement of the second plate relative to the first plate.

Abstract: A method for storing a gas. In some embodiments, the method includes positioning a gas storage system under water, the gas storage system having a gas inlet and injecting gas through the gas inlet into the gas storage system, wherein the gas is compressed. The method may further include venting the compressed gas through the at least one gas port to a storage facility.

Abstract: A mooring method for a moored vessel that comprises a first chain stopper that is fixed to the vessel and is operable to selectively couple an upper chain to the vessel. A chain tensioner is coupled to the vessel and is operable to pull the upper chain. A second chain stopper is fixed to the vessel and is operable to selectively couple the upper chain to the vessel. The chain tensioner engages the upper chain at a location between the first chain stopper and the second chain stopper.

Abstract: A configurable, multi-function vessel that comprises first and second pontoon barges and a plurality of interconnecting barges. The first and second pontoon barges have a plurality of connection members disposed on the inboard sides thereof. The plurality of interconnecting barges are disposable between the inboard sides of the first and second pontoon barges so that a plurality of connection members disposed on opposite sides of the interconnecting barges are adjacent to the connection members on either said first or second pontoon barge. A plurality of connectors releasably couple adjacent connection members so that the pontoon barges and the interconnecting barges form a unitary, oceangoing vessel.

Abstract: A deep draft semi submersible structure wherein the semi-submersible has a center of gravity below its center of buoyancy and the structure is a floating vessel with at least three vertically oriented buoyant columns. Each of the vertically oriented buoyant columns have at least one ballasted compartment and the columns are spaced apart at a sufficient distance to reduce vortex induced vibration amplitude. There are at least two connecting structural sealed trusses connected to the columns below sea level, they are positioned to minimize hydrodynamic wave action on the trusses and to transfer shear loads between the columns while remaining transparent to wave and ocean current motion.

Abstract: Methods for developing an offshore field comprising deploying a lead drilling and production vessel to a offshore field to drill and complete at least one well. Production from the at least one well is initiated and evaluated. A secondary production vessel is selected based upon the evaluated production and is deployed to the offshore field to replace the lead drilling and production vessel and support production of the at least one well.

Abstract: A method for making a deep draft semi-submersible drilling/production vessel having a center of gravity below its center of buoyancy by constructing a plurality of buoyant individual columns. The method connects a pair of columns with at least a first top truss and a first bottom truss. The method additionally floats a connected first and second columns horizontally in water. The method floats the semi-submersible structure to a location for installation. The method concludes by deballasting the semi-submersible structure with connected deck forming a semi submersible drilling/production vessel having a center of gravity below its center of buoyancy with a draft between 300 and 500 feet.