Abstract: A hydrostatic coupling device for rapidly releasing a first object immersed in water from another object resting on the sea bed. The device comprises a seal mounted in a groove in the first object, which in use will be pressed against the other object. The groove is formed as a closed loop delimiting a space at the surface of the first object facing the other object. The seal is formed as a membrane mounted along its sides and dividing the groove into an outer part, open to the ambient water, and an inner part, which via a pipe can be connected to a reservoir above the water surface. This reservoir maintains a liquid column pressure in the inner part, being a certain amount higher than the ambient water pressure. A pumping device removes water from the space delimited by the seal and both objects.

Abstract: A marine unit for location on the sea bed has a cylindrical body and legs which are connected to the body by a pivot adjacent one end of the body. Each leg has a toothed member which engages a common worm driven by a motor. The legs are connected by webs of net. The body and nets nest within the legs for storage, the legs are partly opened for the descent, and are opened fully when the unit reaches the sea bottom to support the unit with its axis approximately vertical.

Abstract: This invention is directed to a novel method and apparatus for constructing artificial islands in relatively shallow bodies of water such as lakes, seas and oceans for use in drilling oil and gas wells and installing storage and production platforms. The method of building an artificial island in a Water-bound area comprises converting a conventionally designed oil tanker, oil/bulk/ore, or oil/ore (O, O/B/O, O/O) hull so that it can be partially submerged by liquid or solid ballast; transporting the hull to the water-bound area where the artificial island is to be created; and partially submerging the hull with liquid or solid ballast so that the bottom of the hull is founded on the bottom of the water body, while a portion of the hull remains above the water level.

Abstract: A jacket tower structure for use in deep water which includes a plurality of tapering jacket sections adapted to be nested, each section including at least three jacket legs. The base and lower jacket sections include cylindrical legs interconnected by box section bracing, the upper jacket sections including cylindrical bracing. The box section bracing is connected to the legs by a unique joint for transmitting stresses to the legs. The box section bracing is floodable for equilizing hydrostatic pressure during and upon installations. Certain transverse box section bracing at ends of adjacent jacket sections include intermediate connection projections for welding during joining of adjacent jacket sections. The cylindrical legs include a plurality of water tight compartments of selected volume, each compartment having one or more check valves for admitting water into the compartments when external water pressure exceeds air pressurization of the compartments.

Abstract: A flexure joint is formed at the base of a buoyant tower structure by piles driven into the ocean floor. The geometric arrangement of these piles increases the buoyant tower's resistance to lateral forces at the base, while allowing rotational displacement about any horizontal axis, and also allows wells to be directed through the piles to formations located a substantial distance from the tower.

Abstract: A method and apparatus is presented for anchoring a tension leg platform to the ocean floor using an anchor having an upper and lower assembly. The anchor's upper assembly is operatively connected to the lower ends of the tethers forming the tension legs of the tension leg platform, and acts to space and align each tether in a vertical manner when the anchor's upper assembly is connected to the anchor's lower assembly, which has previously been secured to the ocean floor by anchor piles.

Abstract: The invention provides a method of constructing an offshore tower structure having a base structure for positioning on the sea bed, a central enclosed tubular column containing services such as conductors and risers and extending from the base structure to above the water level for supporting a service platform which includes positioning the base structure on the seabed, floating the column and legs over the base structure, lowering the column and legs onto the base structure and securing them onto the latter.

Abstract: A mobile platform structure, installation and method for use in arctic waters where the dominant environmental loading threats are posed by winter ice pressures and summer ice floes. The structure includes an ice load bearing, submergible substructure and a platform superstructure of approximately equal lateral dimensions. The substructure has a height approximately equal its depth of submergence when ballasted down onto the sea floor and includes a plurality of peripherally arranged, surface accessible spud guides. The spuds are laterally restrained by the spud guides in the top and bottom walls for transmission of lateral loads therebetween at respective vertically spaced apart fulcrum points and are vertically movable in the spud guides for penetration into high shear soils which may be overlaid by relatively low shear soils whereby the shear capacities of both soils combine with the frictional capacity of the structure/sea floor interface to provide high displacement resistance to lateral ice loads.

Abstract: The present invention generally relates to devices and methods used to suppress the motion of an offshore structure due to wind, wave, seismic, and current forces. More specifically, the invention suppresses structural excitation due to secondary wave forces.The apparatus comprises a mechanical energy absorbing means and a submerged mass. The mechanical energy absorbing means may be a combination of linear or non-linear springs and dampers and is attached to the structure so the vibrating motion may be transferred to the motion damper. The proper weight or size of the damper and mechanical energy absorbing means is determined by first measuring the natural frequency of the structure and the mass of the structure then using those numbers in an equation to calculate the mass and spring constant for the desired apparatus.

Abstract: A platform is provided for use in combination with a foundation affixable to a sea bed to provide a fixed/movable marine structure system for use at selected offshore locations. The platform is capable of alternately existing in a fixed mode in which the platform is releasably coupled to the foundation, and in a floating mode in which the platform is uncoupled from the foundation. The platform comprises a working deck, and a supporting structure including buoyancy adjustment means and securing means. The buoyancy adjustment means preferably comprises ballast adjustment means. Also provided is a marine structure system comprising a platform and a foundation, and a method of coupling and uncoupling the platform from the foundation. The system of the present invention is well adapted for use at offshore locations subject to conditions which may require a platform to be both relatively rigid and stable on site at times and to be safely moved off site at other times.

Abstract: The invention provides an offshore tower structure comprising a base structure for positioning on the sea bed, a central enclosed tubular column 20 containing services such as conductors and risers and extending from the base structure to above the water level, in use, for supporting a service platform 21 and at least three tubular support legs 22, 23, 24 each extending between the base structure at a point spaced apart from the column and an upper portion of the tubular column, the support legs each being rigidly attachable to the base structure and to the column and the base structure providing means for maintaining the spacing between the support legs and the column, in which each support leg is attached to the column by welding and there is means to provide a water tight compartment around the joint from which water can be removed so that the leg can be welded to the column in dry surroundings.

Abstract: A method for ballasting a vessel in which a sequence of subsets of ballast tanks, each subset comprising three tanks of the totality of ballast tanks of the vessel, is used to arrive at a final ballast configuration. For each subset in the sequence excepting the last subset, ballast adjustments are repetitively selected and assigned to members of the subset until a selected ballast adjustment will completely fill or completely empty the ballast tank to which the adjustment is assigned. Thereafter, a new subset is selected. In the final subset of the sequence ballast adjustments are repetitively selected and assigned to members of the subset until the total weight of the vessel and ballast, including the ballast assignments, is within a preselected tolerance of a preselected, desired total weight for the vessel and ballast.

Abstract: Subsea drilling and foundation templates are lowered from a semi-submersible drill rig and levelled utilizing the drill string hoisting apparatus including a heave compensator suspended from the travelling block of the hoisting apparatus, a riser string suspensed from the heave compensator and connected to the template at substantially its center of gravity and further including a constant tension rotary drum air powered hoist supported on the riser string below the heave compensator and having a tension cable secured to a fixed reference point on the seabed such as one of the template supporting piles. The tension on the cable may be selectively adjusted to dampen the motion of the riser string during levelling procedure so that the position of the template with respect to its supporting piles may be referenced and the template secured to the piles when a level condition is reached.

Abstract: A method of conducting offshore well operations including exploration drilling and production from a single floatable platform which is converted from semisubmersible exploration mode to tension leg production mode at a well site.

Abstract: A temporary guide base for use in drilling underwater wells in areas where the bottom conditions are unstable comprises a plurality of boxes opened at the bottom having a centrally disposed hole for casing, and vent means to allow retrieval of the guide bases without causing a suction effect, the guide bases being open to the sea on the bottom to fill the sea water but float in the mud on the bottom.

Abstract: 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.

Abstract: A shallow water drilling barge (46) is supported on a silty water bed (50) of low bearing capacity by providing a submersible platform (74) such as the platform of a jackup drydock (40) with jacking legs (42), floating the jackup drydock into position, ballasting it until it rests on the bottom, floating the jackup drydock into position, ballasting it until it rests on the bottom, floating the drilling barge into position over the platform and floating the barge so that it comes to rest on the platform, with the weight of the barge and jackup drydock as so submerged being less than the load bearing capability of the underlying soil and then jacking down the legs of the jackup drydock to increase its load carrying capability.

Abstract: A steel-reinforced concrete gravity structure mounts a support framework with which to elevate a production deck above sea level. The structures are separately fabricated on shore, assembled in bordering shallow water, transported as a unit to the subsea well site, and subsequently installed on the sea floor.

Abstract: A floatable bottom-founded caisson is disclosed that is suitable for use in ice-covered waters. The annular caisson structure has a frusto-conical upwardly tapered inner wall which reduces skin friction between itself and the core fill material. By the application of heat and the use of insulation, freezing of the core fill material is prevented; this feature, together with the tapered wall, enables the caisson to be easily raised and moved to a new position. The outer, or perimetrical, wall is inclined to aid upward fracturing of the ice impinging on it. The caisson carries a deck structure for the support of offshore drilling or other equipment.

Abstract: A method of erecting a marine structure at an offshore site of a body of water. The structure has a plurality of hollow tubular members associated with it. Examples of such members include skirt piles, conductors, legs, etc. The bottom portion of at least some of the members is sealed by a watertight removable plug with each plug provided with a plurality of normally closed vents. The vents, when opened, permit the pressure on both sides of the removable plugs to become substantially equal. After the structure is transported to the site, the tubular members are oriented substantially vertically with the bottom portion of the members extending downwardly. The structure is then submerged, preferably the bottoms of the tubular members engage the bottom surface of the body of water at the site.

Abstract: An oscillatable marine installation comprises a concrete and steel lattice shaft supported by means of a demountable pivot joint on a base fixed to the-sea-bed and including an anti-torque device. The pivot joint is made up of three parts: a casing fixed to the shaft, a part-spherical housing fixed to the base, and a pivot member. The pivot member has an upper part cooperating with the casing, a flange which can be fixed to the casing, and a lower part-spherical part housing which supports a resilient assembly and a bush fixed on the housing. The anti-torque device comprises a universal joint, concentric with the pivot joint. Two opposite pivots of the crosspiece of the universal joint are supported by the lower part of the shaft and the other two pivots by the base. At least two opposite pivots have damping devices and the pivots supported by the base are mounted on supports the height of which can be adjusted.

Abstract: A shallow water drilling or production barge (46) is adapted for offshore use by means of a novel drydock (40) which has wing walls (52) of substantial freeboard and a platform (74) of essentially no freeboard. Jacking legs (42) extend down through the wingwalls to the sea bed (50). Valves (56) in the wing walls are opened to allow them to partially submerge and lower the platform enough to float the barge into place; and then jacking mechanisms in jacking towers (54) on the wing walls are operated to raise both the drydock and the barge up out of the water. The barge rides or rails 75 supported by roller assemblies on the platform; and after being raised the barge is pulled forwardly and locked in place.

Abstract: An offshore marine combination reach rod and grouting system wherein a reach rod extended from the upper end of an offshore platform leg or piling and piling sleeve to a flood valve connected to the lower end of a leg annulus passes through one or more tee connections as part of a grout feeding system to the leg annulus. The reach rod in the form of a hollow pipe is connected through flexible lines to flush water and grout feeding sources that permit twisting of the reach rod pipe to open and close the flood valve.

Abstract: A device for damping impacts between a load (1) and a floating support (70) while the load is being removed from said support which includes at least one housing (10) on which the load rests. The device includes means (11, 15, 18) for automatically and irreversibly inserting a damping unit (14) between the load and its bearing point on the floating support as soon as the weight of the load is removed from the bearing point.

Abstract: The specification discloses a single point mooring for vessels comprising a base member adapted to rest on the ocean bottom, a cross member joined to the base member at one end thereof and a mooring post member joined to the base member at the opposite end and perpendicular to a plane intersecting the base member and cross member. Placing the single point mooring by floating, towing and sequential flooding is also disclosed.

Abstract: Improvements in an offshore platform and submarine storage facility for highly chilled liquified gas, such as liquified natural gas, are disclosed. The improved facility includes an elongated, vertically oriented submerged anchoring frame to which one or more insulated storage tanks are moveably mounted so they can be positioned at a selected depth in the water. The double piston tank is constructed with improved seals to transfer ambient water pressure of the selected depth to the cryogenic liquified gas without intermixture. This transferred pressure at the depth selected aids in maintaining the liquified state of the stored liquified gas. Structural improvements to the tank facilitating ballasting, locking the double piston cylinders together and further facilitating surface access to the tank for inspection, repairs and removal, and structural improvements to the platform are disclosed.

Abstract: A recoverable or permanent rigid subsea form having retaining walls to contain fill material to stabilize, raise and/or provide a level surface above the sea floor. Portions of the retaining walls comprise hollow tanks that are alternately flooded and emptied to control the buoyancy of selected portions of the form. Alternatively, the retaining walls comprise solid plates. Means are provided in the retaining walls for allowing offshore equipment to pass into and out of the form.The form is set in place on or below the sea floor and the fill material is placed in the form. The fill material is leveled by gravity or other means to form a level surface at the desired elevation. Drilling and/or production equipment can then be placed on the level subsea surface.

Abstract: Method and apparatus for elevating a prefabricated, offshore, well-drilling or other platform on a prefabricated upright support in deep water. The platform is elevated by jacking units on a platform having legs suspended from a superstructure on the support. The upright support is stabilized against wind and wave action by four guy lines anchored at one end to the sea bottom and connected at its opposite end to the drum of winches mounted on two of the caissons. There are two drums in each of the two caissons. Each drum is connected to one guy line and is separately driven by a remotely controlled, reversible hydraulic motor. The motors are operated to maintain the support vertical and the fottings equally loaded; otherwise, uneven penetration of the footings into the sea bed would result. The guy lines are always tensioned against marine and wind forces.The platform is buoyant and has four open caisson wells arranged in the same geometric pattern as the caissons of the support.

Abstract: The invention relates to an off-shore marine structure that provides an elevated support for a drilling and/or production platform. A structure comprised of three interlocking components is provided, the first component being a large foundation base installed on the sea bed; the second being a conical shaped support component which is engagable with the foundation base and which, releasably carries the third platform supporting component. In the preferred form, the platform supporting component comprises a centrally-disposed vertical column, means being provided to facilitate engagement of the column with the platform and the second component and to subsequently elevate the platform to an operating height above sea level.

Abstract: The invention is related to an offshore platform with storage facilities for natural resources, such as LNG. The invention is particularly concerned with the problem of providing sufficient safety in storing such products, e.g., protection against collision with tankers.

Abstract: Sleeve valve for a tank having an opening therein.

Abstract: A drilling sub-base assembly for use from an offshore drilling vessel wherein drilling operations are conducted through a moon pool and at a drilling site where the bottom soil conditions are soft or unstable such that a conventional drilling sub-base dimensioned to pass through the moon pool would not provide an adequate foundational base for the carrying-on of drilling operations. The drilling sub-base assembly includes a main section dimensioned for ease of passage through the moon pool of the vessel and secondary sections pivotally affixed to the main section on at least two opposite sides thereof to be in a substantially vertical position relative to the main section when the drilling sub-base assembly is located in the moon pool and to be in a substantially horizontal position relative to the main section when the drilling sub-base assembly is positioned on the underwater bottom.

Abstract: In the installation of a jacket or substructure component of an offshore platform on the sea floor over an underwater fixture containing one or more wellheads, a jacket is first ballasted to rest in a vertical orientation on the sea floor. Power winches are mounted atop the jacket above the water line and anchored mooring lines are connected to the winches via fairlead sheaves which define points of attachment for the mooring lines to the jacket. The jacket is deballasted to float with a near sea bottom clearance and is maneuvered horizontally with the power winches toward the underwater fixture. Docking guides carried by the jacket engage vertical guideposts driven drilled into the sea floor at preselected locations relative to the underwater fixture to align the jacket with the underwater fixture. The jacket is then lowered into the desired on-bottom position during controlled ballasting procedures. Finally, piles are driven through hollow jacket columns to anchor the jacket to the sea bottom.

Abstract: PCT No. PCT/FR78/00005 Sec. 371 Date Feb. 28, 1979 Sec. 102(e) Date Feb. 26, 1979 PCT Filed June 28, 1978 PCT Pub. No. WO79/00016 PCT Pub. Date Jan. 11, 1979The invention relates to a method for positioning a support structure for installations outside a petroleum platform and to said support structure.The structure comprises a biped tower (2) supporting a bridge (1) which supports a flare (3) at one of its ends. The structure, in folded towing position, floating by means of floats (26) and dead men (10), is towed to the site, the tail of the structure is supported by the platform (40), and the dead men (10) and then the floats (26) are ballasted when the tower (2) is in vertical position. When the feet of the tower rest on the ocean bed (11) the tail is hoisted onto the platform (40) in order to anchor it to the latter and the floats (26) are recovered.The invention is applied to a flare support for a marine platform.

Abstract: An offshore floating tower comprises two coaxial cylindrical enclosures (2 and 11) interconnected by continuous radial bulkheads (10) forming in the upper portion a ring of damping chambers (12) and in the lower portion a ring of buoyancy tanks (4) around a bell-shaped chamber (5) which is partially filled with air to produce pneumatic damping of vertical movement of the tower. The upper portion of the tower is separated from the lower portion by a horizontal slab (3). The upper portion of the internal enclosure is perforated in the vicinity of the horizontal slab.

Abstract: A flooding and grouting valve is provided for use in an offshore jacket. The valve mechanism includes a flood valve portion including an opening to ambient water and a rotatable gate for selectively covering and uncovering the opening. The valve mechanism also includes a check valve mounted on the gate for rotation therewith. The check valve includes a passage which communicates with the interior of the gate, whereby the check valve and gate together form a passage for conducting grout. The check valve is to be connected to a grout supply line such that opening of the check valve is opened by the action of incoming grout. A conduit-type, drive rod is rotatably mounted on the jacket, is connected to the check valve, and serves as a grout conduit. The rod extends to an upper end of the jacket whereby an operator at the water surface may rotate the check valve, and thus the gate, to open or close the flood openings.

Abstract: An offshore submarine storage facility for highly chilled liquified gas, such as liquified natural gas, is disclosed. The facility includes an elongated, vertically oriented submerged frame. An insulated storage tank is movably mounted to the frame so as to be positionable at various depths in the water. The tank is constructed to transfer external ambient water pressure to the liquified gas without intermixture. This transferred pressure aids in maintaining the liquified state of the stored liquified gas.

Abstract: A sea-bottom, off-shore exploitation platform comprising a column having an emerged portion and a base for said column, intended to be laid down and anchored on the sea bottom, wherein the improvement consists in that the base is designed in the form of a tank floating and supporting said column during transport, said tank being sunk at the exploitation place.

Abstract: Apparatus for positioning an off-shore weight structure on a previously positioned sea bed unit during lowering of the weight structure onto the sea bed. The sea bed unit comprises a unit template surrounded by a guide structure in the form of a perimeter frame. The weight structure comprises a base caisson of reinforced concrete and at least one hollow reinforced concrete tower projecting upwardly therefrom for supporting a work deck out of the water.Co-operating contacts are provided on the sea bed unit and in a sea bed unit receiving recess in the lower surface of the base caisson, anda plurality of anchors for location on the sea bed around the sea bed unit and for fixing to the sea bed independently of the sea bed unit, and co-operatingwinches are connected to the anchors by cables. During lowering progressively more accurate guide systems are used. The winches enable the recess to come into contact with the guide structure surrounding the template.

Abstract: The invention relates to a method of assembling and installing a device for exploiting an oil-field. Said device comprises an upper structure comprising two superposed platforms provided with a vertically slidable column, and a lower structure comprising at least two tanks connected to the upper structure by means of support legs. Such a device allows its elements i.e. each of the platforms and the tanks to be fabricated separately, and the assembly to be performed only in floating conditions and not in a dry dock. Furthermore the fabrication can therefore take place in a yard designed for constructions of small size compared with that of the completely assembled device.

Abstract: A method of constructing a hollow column for resting on a base on a submarine bed, comprises the steps of simultaneously starting the construction of a number of elements that are to form the column, causing the partly constructed elements to float, finishing the construction of the elements afloat, bringing the elements into the horizontal position and connecting them together to form the column, said elements being provided with impervious closures at each end thereof and an impervious caisson adjacent each end thereof, and those of the closures and caissons not required when the column is placed in position are dismantled.

Abstract: Off-shore oil field production equipment with a production platform anchored on the ground of the drilling site, comprising a column pivotally connected through a universal cardan joint coupling to a base anchored to the sea bed in connection with a remote-located floating gas flare for burning gas extracted from the oil, wherein said gas flare is carried by a floating structure coming up into the wind while being connected to a swivel head of the column by means of a pivoted holder.

Abstract: A scissored sea-floor well template for positioning spacing of subsea wells or piling in the sea floor. Two arms, each having a pontoon template at each end thereof, are pivotally connected. The two arms are rotated about the pivot to a closed position for transportation to the marine site at which they are to be used. Inasmuch as the template is provided with pontoons, it can be towed and does not have to be loaded on a barge although it could be. Upon reaching the well site the arms are opened so that the pontoon templates assume the desired shape. The arms are then locked in this extended position and the scissor well template is then lowered to the ocean floor.

Abstract: The invention relates to platforms of the off-shore type. It consists principally in arranging the base of the platform in the form of an elongated reservoir able to float and of a sufficient length to serve as a support for a column during transport to the anchoring point. For positioning the reservoir-base on the sea-bed, the reservoir is first of all tilted under the effect of ballasting until one of the ends of the reservoir touches the sea-bed. Then the column is released to assume its vertical position by way of floats connected thereto; and the operation is completed by ballasting to bring the reservoir-base to a horizontal position on the sea-bed.

Abstract: A method and apparatus for fabricating an offshore structure intended to be installed at sea comprising a support structure and a platform mounted on the structure. The platform is made up of one or more pieces that are floatable in water. The support structure is immersed to a depth sufficient for the portion thereof intended for the reception of the platform to be situated near the level of the latter. The platform is then fixed to the support structure which is then made lighter and brought to the place where it has to be installed.

Abstract: A marine platform comprises a caisson unit adapted to be placed onto the submarine ground at a desired offshore site. A tower-like tubular structure comprising a plurality of columns extends vertically upwardly from said caisson unit and with their lower ends integrally fixed to said caisson unit. A deck unit adapted to be provided with petroleum drilling equipment or the like is integrally fixed to the upper ends of said columns. A floating unit is adapted to be displaceably and removably fixed to said columns.

Abstract: A hollow generally circular horizontal float body is provided. The body tapers in thickness from its central portion of its outer periphery and includes upper and lower walls which are inclined downwardly and upwardly, respectively, from the central portion to the outer periphery of the body. A horizontal work platform is spaced above the body and supported therefrom by upstanding supports extending and secured between the body and the platform at points spaced about the central portion of the body. The body includes a central vertical passage therethrough and the interior of the body spaced outwardly of and about the central portion includes structure defining ballast tanks which may be selectively flooded and evacuated of water.

Abstract: An off-shore gravity type platform for supporting a processing installation above the surface of a body of water and for housing processing components, comprising a pressure-resisting watertight central shaft extending from top to bottom of the platform structure, the lower end of the shaft being surrounded by a coffered base structure with a protective wall surmounted by pillars co-operating with the shaft for supporting a bridge, the shaft being so sized that the platform has a positive buoyancy, the top of the protecting wall being located below the level of the body of water, and the pillars being hollow and being filled with concrete after the platform is in place.