Deep Oil Technology Incorporated

Global Marine, Inc.

Chevron Oil Field Research Co.

Edward E Horton

Raymond W Walker

John H Brewer

T A Hudson

William H Silcox

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.

Drilling, production, test, and oil storage caisson

A floating caisson for offshore drilling and production that includes means for increasing the natural period of the caisson and reducing heave, pitch, and roll without increasing the overall length of the caisson. The caisson is self buoyant by means of buoyancy tanks and is held in position by mooring lines. The caisson has a center well through which drilling and/or production risers pass. One or more plates extend radially from the caisson below the water surface. The plates provide additional mass and resistance to environmentally induced motions and thus increase the natural period of the caisson beyond the periods of maximum wave energy. This allows the caisson to be designed with a shallower draft than a caisson without the plates that would normally be used in deep water.

Floating caisson for offshore production and drilling

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.

Deep water piling and method of installing or removing

An offshore apparatus and method for oil operations at a deep water well site wherein a lower hull includes a pontoon portion providing a large water plane area and also includes an upwardly facing body opening, an upper hull is fabricated within said body opening in fully telescoped relation therewith, said upper hull and lower hull being vertically relatively movable, and a deck carried by the upper hull. The pontoon portion has suffient displacement to support the apparatus in towing draft mode. The lower hull and upper hull include floodable compartments for selective ballasting and deballasting to raise and lower the hulls relative to each other in order to submerge the apparatus under stable conditions and to change the draft from towing mode to operating mode in which the hulls are in extended nontelescopic relation at a selected draft. Support lines interconnecting the lower hull and deck are selectively tensioned to aid in the transition from towing draft to operating draft. Interengagable stop shoulders are provided between the upper and lower hulls and at operating draft may be secured to assist in maintaining the extended nontelescopic relation thereof. Guides for relative vertical motion of the upper and lower hulls are provided at the outer surface of the upper hull and the stop shoulder of the lower hull. The support lines may later serve as anchor lines.

Offshore apparatus and method for oil operations

A deep water offshore apparatus for use in oil drilling and production in which an upper buoyant hull of prismatic shape is provided with a passage longitudinally extending through the hull in which risers run down to the sea floor, the bottom of the hull being located at a selected depth dependent upon the wind, wave, and current environment at the well site, which significantly reduces the wave forces acting on the bottom of the hull, a frame structure connected to the hull bottom and extending downwardly and comprising a plurality of vertically arranged bays defined by vertically spaced horizontal water entrapment plates and providing open windows around the periphery of the frame structure, the windows providing transparency to ocean currents and to wave motion in a horizontal direction to reduce drag, the vertical space between the plates corresponding to the width of the bay window, the frame structure being below significant wave action whereby wave action thereat does not contribute to heave motion of the apparatus but inhibits heave motion, the frame structure serving to modify the natural period and stability of the apparatus to minimize heave, pitch, and roll motions of the apparatus. A keel assembly at the bottom of the frame structure with ballast chambers for enabling the apparatus to float horizontally and for stabilization of the apparatus against tilting in vertical position, and taut anchor lines connected to the apparatus at a location of relatively little cyclic movement of the apparatus, the said lines being connected to suitable anchors.

Deep water offshore apparatus

A method of setting out long mooring lines that includes the use of both a traction, or drum, winch and a linear winch. An anchoring vessel is provided with supply drums that contain the mooring line, a traction winch, and a linear winch. When the mooring line is lowered or retrieved, the traction winch, is used to maintain tension on the line until a connector approaches the traction winch. The linear winch is then engaged to maintain tension on the line, with the traction winch under low tension, until the connector passes through the linear winch. The traction winch is then reengaged to maintain all the tension on the line and the linear winch is disengaged until the next connector approaches the traction winch.

Method of installing or retrieving mooring lines indeep water

A submerged tubular tower 10 is connected at its lower end 15 to an ocean floor 11 at a site where at least one subsea hydrocarbon well is to be drilled. A riser duct 22 for each well to be drilled extends from an upwardly accessible connection point 20 at the upper end 14 of the tower to the lower end of the tower. The tower is positively buoyant to stand erect in an unguyed manner. The upper end of the tower is located a substantial distance above the ocean floor at a depth sufficiently small to enable wells to be drilled through the riser ducts, through equipment 19 landed on the top of the tower, using floating drilling equipment 12 designed for use in substantially shallower water depths.

Submerged buoyant offshore drilling and production tower

A development and production facility for an offshore oil or gas field is constructed and drilling of wells is performed using a jack-up drilling platform in an improved manner. The facility is composed of a development well platform and a production platform, each of which is composed of a modular prefabricated unitary deck assembly of substantially turn-key completeness and of a prefabricated jacket or leg assembly to which the deck assembly is matable. Crane or derrick barges are used only to position the deck assemblies on the leg or jacket assemblies after the latter assemblies have been placed erect on and secured to the sea floor by use of the jack-up platform. The development well platform is constructed first so that drilling of development wells can be performed from the jack-up platform through the former platform concurrently with the placement and completion of the production platform.

Method of installing and using offshore well development and production

A tension-leg offshore platform comprises a positively buoyant, floating upper unit in which an operations platform is supported above an ocean surface by a plurality of spaced vertical columns defining buoyancy chambers. The lower ends of the columns are connected to the ocean floor by a corresponding plurality of tension-leg assemblies. Each tension-leg assembly is comprised of a plurality of positively buoyant tubular members having their lower ends connected securely against upward movement to the ocean floor. The tubular members are of substantially equal length less than the pertinent water depth by an amount adequate to cause their upper ends to be located below the area of significant surface wave action yet substantially above the ocean floor. A separate flexible tension member for each tubular member connects the lower ends of the columns to the upper ends of the corresponding tubular members. The positive buoyancy of the platform upper unit, as connected to the tubular members, is greater than the buoyancy it would have if floated at the same draft free of connection to the tubular members.

Tension-leg off shore platform

A tension leg structure for use with a tension leg platform or the like to interconnect an anchor on the sea floor and platform in which the tension leg structure comprises interconnected buoyant pipe members for transmitting tension forces and for withstanding hydrostatic pressure. Each member has internal watertight bulkheads defining a buoyancy chamber. Tremie pipe extends through the bulkheads of each member and has ends terminating in a slipover coupling provided within a joint interconnecting adjacent tension buoyant members.

Tension leg structure for tension leg platform

A pipe construction for utilizing ocean energy including a plurality of toroidal pipe elements stacked one upon the other in coaxial relation to form a cylindrical wall of substantial diameter and length. Sealing means are provided between pipe elements to make leakproof the cylindrical wall, said pipe structure being suspended by a plurality of tension members arranged about the inner circumference of the cylindrical wall. A pipe construction having a circular or a polygonal cross sectional shape and having portions thereof of selected physical characteristics for selected depth of water.

Pipe construction and method of making same

A marine riser system is provided which extends between a floating offshore platform and well means in a seabed formation and which has riser end portions connected in novel manner to the floating platform and to wellhead structure at the well hole. Each end portion of the riser is adapted to yield axially, laterally, and rotatively during movement of the riser relative to the platform and to the wellhead structure. Each end portion of the riser is provided with fulcrum or pivot contacts with hawse pipe carried by the platform and with hawse pipe or casing means provided in the wellhead structure. Bending stresses at the riser end portions are reduced at the platform and at the wellhead structure.

Marine riser system

A means and method to facilitate making a flowline connection between a non-vertically disposed submerged connector means for subsea well operations. A surface vessel carrying a supply of flowline and of tension cable over a subsea well installation lowers one end of the tension cable to anchor the cable adjacent the subsea connector means and after moving away from the subsea installation, a tension control means imparts selected tension to the cable to maintain an approximate catenary curve while flowline is supported from and progressively advanced along the cable to the connector means at the subsea installation. Cable tension is controlled to provide a selected curve of the cable and flowline so that the attitude of the advancing end of the flowline is substantially aligned with the connector means at the subsea installation whereby a flowline connection with subsea pipe installations is effected without or with only minimum assistance from a diver or other subsea robot equipment.

Means and method for making a flowline connection to a subsea connector

A method and apparatus for laying continuous pipe particularly for offshore oil installations and wherein said continuous pipe is pre-formed into flat spirals of pre-selected inner and outer diameters depending upon available handling equipment and arranged in stacks in which each flat spiral is interconnected with the adjacent flat spiral. A stack of flat pipe spirals is positioned on a power driven rotatable pipe spiral carrier mounted on a deck of a pipe laying vessel. Pipe is withdrawn from the stack of spirals by rotating the pipe carrier and moving the pipe through pipe straightening and tensioning means, after which the pipe is fed to suitable pipe laying means for connecting the pipe to subsea installations.

Growing community of inventors

Rancho Palos Verdes, CA, United States of America

Edward E Horton