Abstract: A universal catenary riser support that can be designed to accommodate all riser pipe diameters typically considered for production of offshore hydrocarbons and allows the catenary riser to exit from the vessel at any azimuth angle and at a wide range of angles from the vertical. The support structure at the keel of the offshore structure is provided with a receptacle to receive a curved riser segment. The curved riser segment is adapted to be received in the receptacle. The curved riser is also adapted to receive a vertical riser section through the offshore structure. Relative motions between the catenary riser and the offshore structure are accommodated by a tapered section of riser or flexible joint attached to the curved riser section. A removable plug may be provided in the curved riser section to prevent water from entering the catenary riser during installation in the offshore structure.

Abstract: A subsea hydraulic control module that is totally enclosed such that the hydraulic fluid does not contact the seawater. The majority of the power for the module comes from the hydrostatic pressure of the sea itself. Two oil-over-seawater actuators each have an internal piston that separates the oil from the seawater. Each actuator is provided with two solenoid valves that control the flow of seawater. A fluid line and one solenoid valve on the seawater side of each actuator is in fluid communication with a seawater recovery reservoir. These two valves are also in fluid communication with each other through a common fluid line to the seawater reservoir. The remaining solenoid valve on the seawater side of each actuator may be selectively opened or closed to the ambient seawater. A hydraulic line on the oil side of each actuator is in fluid communication with the equipment to be controlled.

Abstract: A floating offshore drilling/producing structure. The structure is formed from a plurality of closely spaced vertically oriented buoyant columns on which one or more modules or decks may be placed to support process equipment, a drilling rig, utilities, and accommodations for personnel. The columns are held in the spaced relationship by a plurality of horizontal plates spaced along the length of the columns and vertical plates located near the bottom of the columns and near the top of the columns. Drilling and/or producing is accomplished through risers located approximately in the center of the structure. The structure includes fixed ballast, an oil storage area, and voids and variable ballast for offsetting the lighter weight of the stored oil. The columns have a smaller water plane area than the horizontal plates.

Abstract: A riser guide and support mechanism for a floating vessel, and particularly a spar type structure, where the buoyancy can stem extends nearly the entire length of the floating vessel. A riser centralizing element is provided on the riser near the lower end of the buoyancy guide stem. Riser bend limiting elements are positioned on the riser so as to extend above and below the riser centralizing element. Since the buoyancy cans and buoyancy can stem are not required to rotate relative to the stem guides on the floating vessel, the stem guides can be formed from pipe sections that provide a much larger bearing area than is customary.

Abstract: A method and apparatus for rapidly deballasting and lifting a substructure in a marine environment to a level where it will engage with a deck so that both act together as one body. Generally, the installation is carried out as follows. The substructure is towed to the mating site and upended (if necessary). The substructure may be connected to a temporary mooring and fixed ballast installed if necessary. Selected compartments in the substructure are filled with sea water until the substructure is submerged below the water line to a desired depth. A predetermined quantity of compressed air is pumped into lower tanks in the substructure. The deck to be joined with the substructure is positioned above and in alignment with the substructure. The proper valves are opened to allow the compressed air in the lower tanks to flow into the upper tanks that contain sea water. The compressed air displaces the sea water from the upper tanks.

Abstract: An apparatus and method for the installation of a deck on an offshore substructure. The invention is particularly useful with a floating substructure. Two independent pontoons each have two columns spaced apart from each other that extend upwardly from the pontoons. On each pontoon, a support beam attached to the columns spans the space between the columns. Each pontoon is provided with ballast tanks that allow the pontoons to be selectively ballasted or de-ballasted to control pontoon depth for receiving a deck or installing a deck on an offshore substructure. The pontoons may be ballasted down during transit of the deck such that the main body portion of the pontoons is below significant wave action and the columns present a relatively small water plane area. The pontoons allow the deck to be placed directly above the offshore substructure. For a floating substructure, the pontoons are ballasted while the floating substructure is simultaneously de-ballasted to transfer the deck to the floating substructure.

Abstract: A drilling, production, test, and oil storage caisson for use in deep water offshore well operations. Separate low pressure and high pressure drilling risers are independently supported on buoyancy modules. Multiple drilling and production risers are left in the water and connected to the drilling rig and well(s) as needed to prevent the need for the raising and lowering of different risers during the various steps involved in beginning and completing wells. Surface and lower BOP stacks are utilized. Means for controlling the accelerations and velocity of the drilling riser buoyancy modules in the event of riser failure is provided. A subsea tree with dual master valves allows for production directly through a vertical production riser, flowline, to the production manifold on the caisson. A twisted tubing production riser is formed from three strings of tubing that are used for the flowline, annulus, and conduit for control lines.

Abstract: A stress relieving joint for use with riser pipe in floating systems wherein a vessel is subject to variable motion caused by wind, currents, and wave action. The riser pipe has one end connectable to the sea floor and an upper portion adapted to pass through a constraining opening at the bottom of the vessel. A ball joint and socket assembly is removably attached to the keel at the constraint opening. A sleeve is attached at substantially its midpoint in the ball joint. Riser pipe received in the sleeve is provided with wear strips that reduces the rate of reduction in wear surface diameter.

Abstract: A drilling, production, test, and oil storage caisson for use in deep water offshore well operations. Separate low pressure and high pressure drilling risers are independently supported on buoyancy modules. Multiple drilling and production risers are left in the water and connected to the drilling rig and well(s) as needed to prevent the need for the raising and lowering of different risers during the various steps involved in beginning and completing wells. Surface and lower BOP stacks are utilized. Means for controlling the accelerations and velocity of the drilling riser buoyancy modules in the event of riser failure is provided. A subsea tree with dual master valves allows for production directly through a vertical production riser, flowline, to the production manifold on the caisson. A twisted tubing production riser is formed from three strings of tubing that are used for the flowline, annulus, and conduit for control lines.

Abstract: A catenary riser support, for a floating offshore structure, that receives the riser and is attached to the floating offshore structure. The catenary riser support is formed from a tube that is rigidly attached to the floating structure and a flex joint in line with the catenary riser. The tube includes a gradual bend that complements the natural catenary curve of the catenary riser. A pipe adaptor attached in line with the flex joint and riser allow the flex joint to be pulled up against the tube. The flex joint allows the catenary riser to move relative to the floating structure.

Abstract: A shallow draft floating offshore drilling/producing structure. The structure is formed from a buoyant hull on which one or more modules or decks may be placed to support process equipment, a drilling rig, utilities, and accommodations for personnel. Drilling and/or producing is accomplished through a center well in the hull. The hull includes fixed ballast, an oil storage area, and voids and variable ballast for offsetting the lighter weight of the stored oil. The hull is designed to have a relatively small water plane area. The hull is also designed to have roll and pitch periods that are detuned from waves in the area that the hull is to be installed.

Abstract: A dynamically positioned loading buoy for transferring liquid from an offshore structure to a tanker. The loading buoy is a floating hull. The hull is provided with thrusters that are used to position the loading buoy and tanker in a safe position relative to the offshore structure. The use of thrusters on the loading buoy eliminates the need for anchors and mooring lines for the loading buoy. The transfer hose used to transfer oil between the offshore structure and the loading buoy may be stored on the loading buoy or the offshore structure. The transfer hose used to transfer oil between the loading buoy and the tanker is stored on a reel on the loading buoy.

Abstract: A dual draw works hoisting apparatus. A single derrick structure is provided for two drilling rigs. The crown block platform receives the crown blocks for both drilling operations such that both crown blocks are slidable along the crown block platform. The hoisting lines are reaved in a conventional manner, except for the dead lines. The dead lines from the two crown blocks are connected together by means of a sheave assembly which is locked in position during normal independent operation of the crown blocks and their respective travelling blocks. To provide increased lifting capacity for lifting the drilling riser, the crown blocks are moved closer together on the platform such that the travelling blocks may be attached to a spreader bar to be positioned above a drill slot and attached to the drilling riser. The sheave assembly connecting the two deadlines is unlocked to allow relative movement between the two deadlines during simultaneous use of the draw works for both travelling blocks.

Abstract: A riser tensioning device that utilizes parallel air cans. A stem having an inner diameter larger than the outer diameter of the riser is positioned around the riser and is fastened in position at the wellhead of the riser on the offshore structure. A yoke attached to the stem supports a number of sleeves around the stem. Each sleeve receives a variable buoyancy air can. The sleeves and air cans are provided with a retainer that retains the air cans in the sleeves and transfers the vertical loads of the air cans to the sleeve. The retainer is also designed to allow the air cans to be selectively removed from their individual sleeves without the need to pull the entire riser assembly.

Abstract: A catenary riser support tube that receives the riser and is attached to the floating offshore structure. The support tube is attached to the floating offshore structure at an angle from the vertical so as to be in line with the natural angle that the installed catenary riser would assume on a calm day. The support tube is attached to the floating offshore structure at different points along the length of the support tube and thus flexes about its attachment points to the floating structure. This minimizes stresses on the catenary riser.

Abstract: A drilling, production, test, and oil storage caisson for use in deep water offshore well operations. Separate low pressure and high pressure drilling risers are independently supported on buoyancy modules. Multiple drilling and production risers are left in the water and connected to the drilling rig and well(s) as needed to prevent the need for the raising and lowering of different risers during the various steps involved in beginning and completing wells. Surface and lower BOP stacks are utilized. Means for controlling the accelerations and velocity of the drilling riser buoyancy modules in the event of riser failure is provided. A subsea tree with dual master valves allows for production directly through a vertical production riser, flowline, to the production manifold on the caisson. A twisted tubing production riser is formed from three strings of tubing that are used for the flowline, annulus, and conduit for control lines.

Abstract: A deep water pile and installation and removal method that eliminates the need for underwater hammers or pile drivers. The pile is a hollow tube that is open at the lower end and provided with a fitting at the upper end for attachment to a lowering pipe. The fitting at the upper end also for fluid communication between the lowering pipe and the pile. Injecting air into the lowering pipe draws water from the lowering pipe and pile. This creates a hydrostatic pressure differential whereby the greater pressure on the outside of the pile head forces the pile into the sea floor. Removal of the pile may be accomplished by injecting high pressure water into the pile through the pile head. The high pressure water injection aids in overcoming the hydrostatic pressure on the outside of the pile head.