Abstract: A method includes providing a lower platform block (300) including a first frame (315), a plurality of docking tubes (305) connected to the first frame, and a plurality of first conductor tubes (310) connected to the first frame. At least a first jacket connector block (400) including a second frame (415) and a plurality of second conductor tubes (405) connected to the second frame is releasably coupled to the lower platform block to align the second conductor tubes with the first conductor tubes. A platform deck block (500) including a third frame (515) defining a deck and a plurality of third conductor tubes (505) connected to the third frame is releasably coupled to the first jacket connector to align the third conductor tubes with the first conductor tubes.

Abstract: A platform for a semi-submersible floating type offshore structure according to an exemplary embodiment of the present invention includes a main body which is installed on the sea and has an arrangement structure in which a plurality of pontoons is combined to form a plurality of polygonal shapes; and a protrusion member connecting unit which extends from each corner of the main body and connects a protrusion member outwardly protruding from the main body to the main body.

Abstract: The invention relates to a unit, having a floating wind turbine, which has a floating foundation, and having a floating mooring buoy, which can be connected to the floating foundation of the floating wind turbine and which has at least one anchoring means for anchoring the mooring buoy to the bed of a body of water, characterized in that the floating foundation of the floating wind turbine has a hole for holding the mooring buoy.

Abstract: According to one or more embodiments disclosed herein is a method of transporting equipment between sea-surface and seafloor by providing a structure with equipment mounted thereon. The equipment may be liquid storage tanks, pumps, compressors, separators, metering systems, energy sources, communication systems, buoyancy tanks, and the like. The structure is used for disposal and installation in a subsea environment by changing the volume of buoyancy material within at least one buoyancy tank.

Abstract: A foundation structure for locating an object mounted on the foundation structure on a sea bed or a river bed comprises an integral buoyancy device having variable buoyancy and a rigid control surface. The integral buoyancy device is movable relative to the foundation structure to vary the position of the rigid control surface and to control the position of the center of buoyancy relative to the position of the center of gravity. This stabilizes the foundation structure during submergence and surfacing. A method for controlling the deployment and retrieval of the foundation structure is also described.

Abstract: A method for installation of an offshore wind turbine. The method includes prefabrication of a foundation that provides buoyant force and uprighting force to the foundation so as to keep it upright without external forces. The method further includes installation on a dock that includes assembling the offshore wind turbine into a complete set, and finishing testing in a state of the complete set. The method further includes transporting the complete set to an offshore site in a way of floating on the water, and then offshore installation that includes sinking the complete set onto a sea bed by gravity on the offshore site, and fixing the foundation to finish the installation. The present invention also provides a method for recovery of an offshore wind turbine, which is performed generally in steps reversed to the method for installation.

Abstract: A method for mounting at last one tidal turbine and its associated support structures in a river or sea bed. The turbine and associated support structures are joined to a base of such weight as to involve gravitational forces of such magnitude as to be sufficient to withstand forces acting to tend to displace the turbine and its associated support structures. The base structure can be pre-assembled and transported to a required location of installation by lowering to the sea or river bed. Conveniently, the transportation is by means of an installation vessel incorporating a facility for lowering the entire assembly including at least one turbine, a support column, and the base structure in a controlled manner to rest at a desired position on the river or sea bed.

Abstract: The invention relates to an offshore installation method of a wind power generator and its fabrication segments. A prefabricated wind power generator is finished at a first location, and then carried by a ship to a second location for installation, largely saving installation time. With a tower inserted down through a base to shrink height of the generator, the ship can not only effectively diminish shaking posed by wind and sea waves, advancing steadiness of delivery, but also be one with smaller tonnage to save cost.

Abstract: The invention relates to a supporting element (8) for an offshore wind turbine (3), comprising a base body (1) formed by a circular or polygonal basement (4), a shaft (5) with vertical walls and a plurality of vertical cavities (6) extending over the entire height thereof and a slab (2) dispose on the shaft (5) of the base body (1), on which slab (2) a wind turbine (3) is positioned and secured. The base body (1) of the supporting element (8) is produced using sliding formwork, from the basement (4) up to the upper base thereof. In addition, the method includes the following steps: ballasting the supporting element (8) by partially filling the above-mentioned vertical cavities (6); seaward towing the supporting element (8) from the production site thereof to the offshore wind turbine installation site; anchoring the supporting element (8) by filling the vertical cavities (6) completely; until the supporting element (8) rests on a stone bed (19) on the sea bed; and mounting the wind turbine (3).

Abstract: Embodiments of gravity base structures are disclosed that comprise first and second elongated base sections separated by an open region and configured to support the on-bottom weight of the structure and be supported by the floor of the body of water, and an upper section positioned above the open region and configured to extend at least partially above the water surface to support topside structures. Some embodiments further comprise first and second inclined sections coupling the base sections to the upper section.

Abstract: Embodiments of gravity base structures are disclosed that comprise first and second elongated base sections separated by an open region and configured to support the on-bottom weight of the structure on a seabed, and an upper section positioned above the open region and configured to extend at least partially above the water surface to support topside structures. Some embodiments further comprise first and second inclined sections coupling the base sections to the upper section. Some embodiments comprise a skirt structure below the base sections for facilitating engagement with the seabed. Some embodiments comprise selectively fillable internal fluid chambers to facilitate raising and lowering the structure in a sea and relocating the structure.

Abstract: A structure (20) for loading and unloading at least one fluid transport ship (1): a ship (1) mooring platform (21), comprising at least one concrete caisson (22) having an opening and closing device for moving the caisson by filling water, between a flotation position for transporting the platform, and a position anchored at the bottom of the sea. The platform comprises a submerged lower anchoring portion and an upper portion, partially outside of the water, for berthing the ship.

Abstract: Process for installing an offshore tower, specifically a substructure, which basically comprises the following steps: a) dry manufacturing a foundation comprising a block (1, 1?) basically made of concrete and dry manufacturing a base section (25) of a shaft (2); b) applying said base section to said foundation block, forming a unit called the “starting unit”; c) moving said starting unit to the installation point of said substructure; and d) actuating in a controlled manner, first ballast valve means in such a manner that said starting unit sinks until resting on the seabed; having placed said foundation block or said starting unit in the body of water where the installation point said substructure is located.

Abstract: The invention relates to a system for installing tubular foundation elements having open ends, in particular (mono)piles, in an underwater ground formation, comprising an hydraulic driver, an anvil, and an adaptor for transmitting energy from the anvil to the toe of the foundation element, which adaptor fits inside the tubular foundation element.

Abstract: The present invention provides a method for installation of an offshore wind turbine, comprising a step for prefabrication of a foundation, a step for installation on the dock, a step for transportation and a step for offshore installation. The foundation provides buoyant force and uprighting force to the entire structure so as to keep it upright without external forces; the step for installation on the dock comprises assembling into the complete set, and finishing the test in a state of complete set; in the step for transportation, the complete set is transported to the offshore site in a way of floating on the water; the step for offshore installation comprises sinking the complete set onto the sea bed by gravity on the offshore site, and fixing the foundation to finish the installation. The present invention also provides a method for recovery of an offshore wind turbine, which is performed generally in steps reversed to the method for installation.

Abstract: A foundation structure for locating an object mounted on the foundation structure on a sea bed or a river bed comprises an integral buoyancy device having variable buoyancy and a rigid control surface. The integral buoyancy device is movable relative to the foundation structure to vary the position of the rigid control surface and to control the position of the centre of buoyancy relative to the position of the centre of gravity. This stabilizes the foundation structure during submergence and surfacing. A method for controlling the deployment and retrieval of the foundation structure is also described.

Abstract: Embodiments of gravity base structures are disclosed that comprise first and second elongated base sections separated by an open region and configured to support the on-bottom weight of the structure on a seabed, and an upper section positioned above the open region and configured to extend at least partially above the water surface to support topside structures. Some embodiments further comprise first and second inclined sections coupling the base sections to the upper section. Some embodiments comprise a skirt structure below the base sections for facilitating engagement with the seabed. Some embodiments comprise selectively fillable internal fluid chambers to facilitate raising and lowering the structure in a sea and relocating the structure.

Abstract: A support structure for use in the offshore wind farm industry, and a method of manufacturing and installing same, including a foundation for installation on a seabed below a body of water and a tower connected to and extending upwards from the foundation and being capable of supporting at least an equipment unit. The foundation includes a bottom slab and a wall extending upwards from the bottom slab, thereby defining a first cavity for holding ballast and for providing buoyancy during tow-out and installation. The foundation further includes a circumferential skirt extending downwards from the bottom slab, thereby defining at least one compartment underneath the foundation.

Abstract: A building over the water, maneuvering methods for the building and hosting sites of the building. The buildings including a superstructure (A) provided a floor structure (1) that is placed over a water surface (2) on which an inhabitable subassembly (3) is positioned, a support (B) sitting on ground (4) positioned under the floor structures (1), and mobile floating docks (C) with variable and controllable buoyancy that includes a load carrying platform (5) positioned under the floor structure (1). The superstructure (A) is held above the water surface (2) by the supports (B), that sit on the ground (4), and respectively carried by the floating docks (C), the superstructure being detachable from the ground (4), and transportable on water on the mobile floating docks (C), thus being possible to reposition the superstructure (A) on ground (4), at a destination of choice.

Abstract: A floating platform for drilling after or production of hydrocarbons comprises a semi-submersible main platform (2) carrying process and/or drilling equipment at its upper surface (7), and which is designed as a vertical, essentially flatbottomed cylinder. The main platform (2) is provided with a central vertical shaft (8) which at its lower end is adapted for reception and releasable locking of an anchoring buoy (3) carrying fastening equipment for anchoring lines (10) and for risers (14, 15) and umbilicals.

Abstract: The present invention describes an offshore foundation system (10,10a,10b) that is operable for preloading after self-weight installation on a seabed without relying on additional or external ballasts. The foundation system (10,10a,10b) is also operable for extraction by reversing the process of preload operation. In one embodiment, the foundation system (10) comprises a reaction base (20) and suction compartment (60). In another, the foundation system (10a,10b) comprises a plurality of units of reaction base (20) and suction compartments (60), with the units being connected by bridging structures (21). In yet another, the foundation system comprises a reaction base (20) and a plurality of suction compartments (60). A closed-top of the suction compartment (60) projects above the reaction base (20) so that, in use, there is a gap h between a top of a soil plug inside a suction compartment (60) and its closed-top.

Abstract: The support (1) includes a working deck (2) and floatation members (3) supporting this deck (2). According to the invention, the spacing between the vertical axes (Z) passing through the centre of the floatation members (3) is such that the sum of the moments, taken in relation to the horizontal axis passing through the centre of the support (1) is perpendicular to the swell direction, of the vertical excitation forces of the swell on the floatation members (3) situated on one side of the vertical plane (P) passing through this horizontal axis is equal to the corresponding sum associated with the floatation members (3) situated on the other side of this plane, when the swell period is equal to the period of a swell having this direction and of which the yearly probability of being encountered on the site or the support where it is installed is 1/100.

Abstract: An apparatus for use in offshore oil or gas production in which a plurality of vertical stabilizing columns are supported on a submerged horizontal water entrapment plate is provided to support minimum offshore oil and gas production facilities above a subsea wellhead, or subsea processing facilities, or a submarine pipeline, and whose main function is to provide power or chemicals or to perform other operations such as compression, injection, or separation of water, oil and gas. The apparatus is maintained in the desired location by a plurality of mooring lines anchored to the sea-bed. The respective size and shape of the columns and water entrapment plate are designed to provide sufficient buoyancy to carry the weight of all equipment on the minimum floating platform and mooring lines, umbilical and risers attached to it, and to minimize the platform motion during normal operations.

Abstract: A method and system for attaching a TLP to its tendons using pull-down lines to rapidly submerge the hull to installation draft while compensating for inherent hull instability during submergence and to provide motion arrest and aid in station keeping. The system includes tensioning devices mounted on the TLP, usually one for each tendon. Each tensioning device is equipped with a pull-down line which is connected to the corresponding tendon. The TLP hull is submerged to lock-off draft by applying tensions to the pull-down lines connected to the top of the tensions, or by a combination of applying tensions to the pull-down lines and ballasting the hull. As the tensioners take in pull-down line, the hull submerges, i.e. the draft increases.

Abstract: A bottom-supported jack-up rig has a hollow ring mat with a central opening for accommodating a lower portion of a hull nested therein when the rig is in transit. The ring mat has a predetermined surface footprint sufficient to provide stability to the rig when embedded in the sea bottom. The mat buoyancy helps support the hull and the legs in a floating position when the rig is in transit, while allowing lowering of the mat to the sea bottom without assistance of a ballasting/de-ballasting means.

Abstract: Platform for drilling after or production of hydrocarbons at sea, consisting of a semi-submersible platform body which supports drilling and/or production equipment on its upper surface. The platform body is designed as a vertical mainly flat bottomed cylinder which is provided with at least one peripheral circular cut-out in the lower section of the cylinder since the centre of buoyancy for the submerged section of the platform is positioned lower than the centre of gravity of the platform.

Abstract: A marine buoy for the offshore support of subsea production and drilling activities that has a closed-bottomed base section with a solid ballast and variable ballast chambers, a chamber in the base section for storing equipment and supplies, and an upper section with a smaller cross-sectional area than the base section having an elevator shaft leading from the top of the upper section to the chamber in the base section. The upper section supports a deck for housing process equipment for operations that the marine buoy is supporting.

Abstract: A bottom-supported jack-up rig has a hollow ring mat with a central opening for accommodating a lower portion of a hull nested therein when the rig is in transit. The ring mat has a predetermined surface footprint sufficient to provide stability to the rig when embedded in the sea bottom. The mat buoyancy helps support the hull and the legs in a floating position when the rig is in transit, while allowing lowering of the mat to the sea bottom without assistance of a ballasting/de-ballasting means.

Abstract: A floating platform to provide fluid separation and storage of hydrocarbon effluents and the like. The platform includes a floating hull structure with a hollow central section and a center assembly mounted within the hollow central section and being retractable and extendable below the hull. A floating platform is described wherein fluid separators and/or storage vessels are disposed within the floating hull to provide additional separation capacity. The floating hull may also house ballast tanks and liquid storage tanks. Additionally, fluid separators may be housed within the central section.

Abstract: A semi-submersible, multicolumn, deep draft, floating offshore oil and gas drilling and production platform comprises a floating hull having an adjustably buoyant base, a plurality of columns vertically upstanding from the base, and an equipment deck that is supported atop the columns when the platform is operationally deployed. Each of the columns comprises a cellular structure that includes a plurality of elongated tubes having a variety of cross-sectional shapes extending from the base to the top of the column. Each of the tubes defines one or more closed compartments. At least one of the compartments has a buoyancy that is fixed, and at least another one of the compartments has a buoyancy that is adjustable. The buoyancy of the compartments and the base can be controllably adjusted with pressurized air to provide a safer and less costly method for deploying the platform for offshore operations.

Abstract: A heave suppressed, floating offshore drilling and production platform comprises vertical columns, lateral trusses connecting adjacent columns, a deep-submerged horizontal plate supported from the bottom of the columns by vertical truss legs, and a topside deck supported by the columns. The lateral trusses connect adjacent columns near their lower end to enchance the structural intergrity of the platform. During the launch of the platform and towing in relatively shallow water, the truss legs are stowed in shafts within each column, and the plate is carried just below the lower ends of the columns. After the platform has been floated to the deep water drilling and production site, the truss legs are lowered from the column shafts to lower the plate to a deep draft for reducing the effect of wave forces and to provide heave and vertical motion resistance to the platform.

Abstract: An apparatus for offshore production of hydrocarbon fluids is disclosed. The apparatus comprises a base and a buoyant structure secured to said base and connected or adapted to be connected to a subsea well or wells. The key characteristics of the apparatus are that: (A) the apparatus includes storage facility means for fluid(s) received from the subsea well or wells and/or for processed fluid(s) produced by the apparatus; (B) the buoyant structure is tethered to the base by a plurality of flexible tethers; and (C) the buoyant structure comprises (i) a sub-surface housing containing facilities for processing fluids received from the subsea well or wells via said storage facility in said base; and (ii) a column extending upwardly from the housing to a level above the sea surface. The invention also relates to the buoyant structure per se.

Abstract: A submersible floating dock which can be sunk beneath the water line in the event of the approach of a violent storm for protection of the dock against wave action, storm surge, and high winds. A dock with a deck supported on hollow floatation chambers is attached to pilings by rings. The rings allow the dock to move up and down in response to changes in the water level. As a storm approaches water is allowed to enter the hollow floatation chambers which are ordinarily filled with air. This causes the dock and deck to sink beneath the water line making it resistent to damage from storm surge, wave action, and high winds. After the storm has passed, pressurized air is introduced into the floatation chambers forcing the water in the floatation chambers out of the chamber. The air increases the buoyancy of the floatation chambers, hence, of the dock so that it rises above the water line for use by an owner after the danger of storm surge, high winds, and waves has passed.

Abstract: An oil drilling barge stabilization system and method provide that an array of substantially vertically-oriented piles is formed in the sea bed to a depth beneath the sea bed that finds solid support. A barge is towed into position over the array of piles, and the barge is partially flooded with ballast to lower it in the water so that a set of cylindrical tubes is positioned to surround top ends of at least some of the piles. Air is then forced into the tubes to force the water out the bottom of the tubes, to create a dry environment for workers. Workers weld the tubes to the piles. The air pressure is removed from the interior of the tubes so that water may again flood the bottom of the tubes. The joints between the tubes and piles secure the barge to the array of piles, even in the face of varying tides, currents, and ice flow conditions. The barge may be used to support oil rigs and a variety of other support facilities.

Abstract: Apparatus for providing an offshore drilling operation in a sea, the apparatus comprising a drilling derrick support structure (2) having a base (4) to rest on the sea-floor (5) and a deck (7) to support a drilling derrick (1), the structure being in the form of a concrete block (2) having a hollow cavity to enable the block (2) to be floated to the site where drilling is to take place and being adapted to receive ballast into the cavity in such a way and in a sufficient quantity as to cause the block (2) to sink base-first and rest upon the sea-bed with the deck (7) clear of the surface of the sea, a drilling derrick (1) for mounting on the deck (7) of the block (2) and a tender assist barge (3) for transport to the site in down to 2 m of water to provide services, supplies and equipment to the drilling derrick (1).

Abstract: A jack-up platform of the type having a buoyant upper barge (10) mounted so that it can be moved along the length of bearing legs (12), mechanical mechanism (18) for moving the legs (12) relative to the barge (10), and submerged storage tank (14) intended to rest on the bottom. The tank (14) has a lower opening (26) allowing the inside of the tank (14) to be placed in contact with the marine environment. The tank defines a bell-shaped/inverted U-shaped cavity confining an air bubble (30) in its upper part. The tank (14) is connected to the lower end of the legs (12) so that it can be moved relative to the barge (10) from the mechanical mechanism (18) for moving the legs.

Abstract: Improvements to a ring pontoon semisubmersible vessel. The centerlines of the corner columns ar displaced with respect to the axial centerlines of the forward and aft portions of the ring pontoon. Additionally, the centerlines of the corner columns may be displaced with respect to the axial centerlines of the starboard and port portions of the ring pontoon. The superstructure deck may be supported by radial braces extending from the ring pontoon to locations on the superstructure deck which are inward of the ring pontoon.

Abstract: A deep water platform, suitable for use as a hydrocarbon exploration or production facility in very deep offshore waters, and a method of constructing the same are shown. The platform is positioned on top of a buoyant leg structure. During normal drilling operations the platform is anchored by a gravity base tethered with pre-tensioned cables to the buoyant leg structure. According to the invention, the gravity base is retractable to permit the platform to be moved from site to site within a drilling region. Long distance relocation is also possible by retracting the gravity base, disassembling the platform, transporting the component parts, and reassembling the rig in a new location.

Abstract: A large semisubmersible building is made up of a submerged section installed underwater, an intermediate section consisting of a plurality of column structures erected on the submerged section at specified intervals, and an above-water section built upon the intermediate section so that it is always situated above water. The submerged section is made larger than the above-water section. Because of this construction, the large semisubmersible building remain stable and stationary at a specified depth of water even in stormy weather conditions. When the water level changes or when the specific gravity of the building changes as a result of changes in the weight of goods stored in the building, the semisubmersible building can be stably held at the specified depth of water.

Abstract: An offshore double cone structure for operation on an ocean foundation has a double-cone concrete shell having a neck ring at the top of the shell and a base caisson that supports the double-cone shell. The caisson rests on the ocean foundation. The environmental loads, topside weight, and self weight of the double-cone shell are transferred by double-cone shell action through the base caisson to the foundation. The base caisson's exterior wall can be either vertical or sloping. The neck ring is at an elevation sufficiently high that the wave and ice interactions with the neck ring do not increase global ice loads acting on the structure. The neck ring has sufficient area to provide room for facilities through the neck.

Abstract: A submersible mobile caisson having ice crush resistance for adapting semi-submersible mobile offshore drilling units and mobile offshore oil well production rigs, which are ice crush sensitive for use in ice bearing offshore ocean waters, is provided. The caisson comprises a floatable generally four sided structure composed of front and rear outer walls, and opposing side outer walls, with the rear outer wall having a removable entrance door. Inner walls are positioned in a spaced apart, opposing relationship with each of the outer walls, and so that the inner and outer walls define a perimeter structure and the inner walls define a cavity which is located within the perimeter structure. The perimeter structure has a plurality of ballast compartments which permit the caisson to float or be sunk so as to rest on the ocean floor. A drilling/production moon pool system is also provided in the perimeter structure.

Abstract: An improved columnar support for offshore drilling platforms intended for installation in a body of water such as the ocean, comprising a cylindrical shaft of unitary cemetitious construction, a frustrum shaped hollow capital having a first peripheral flange, a frustrum shaped hollow base having a second peripheral flange and seals, which may include removable plugs in the open ends of the capital and the base for creating a scuttle opening therein to admit water and sink the columnar support at a designated position on the sea floor.

Abstract: A structure that is floatable on a ocean surface and that is fixable relative to an ocean bottom. The structure includes an array of floatable, submersible caissons and a floatable box girder capable of supporting a modular superstructure. The box girder is floated to a position on the ocean surface above the submerged array of caissons. The array of caissons is then raised to engage and connect with the box girder. The caissons may also be secured to the ocean bottom.

Abstract: A mobile submersible caisson is employed to drill for and recover petroleum products from subsea wells and to deliver the products to shore or to vessels at the well site. The well drilling technique applies to water depths beyond 300 ft. and in areas where severe winds, waves, spray and frigid atmosphere can cause long downtime or make it impossible to maintain the positions of surface platforms for extended periods of time. Caissons containing drilling, completion, workever, separation, pumping and compressing equipment are towed to sea in the caisson in the horizontal position. At the work site the caisson is erected, connects an attached wire cable to a platform placed on the sea bottom, and is submerged and winched down. The caisson mates and becomes sealed with the platform, providing a one atmosphere working space for the drilling crew. Water between the caisson and the platform is pumped out so this area can also be used as a work area.

Abstract: A marine structure, for example an offshore production plantform comprises a floating base section, which can be flooded, having caissons thereon and a topsides mounted on the caissons. The caissons comprise at least two telescopic sections,the uppermost section carrying the topsides and the lowermost being mounted on the base. The structure can be installed by supporting hte topsides for example, using the derrick of a jack-up rig, and then partially flooding the base section until the jack-up rig is supporting the topsides. On lowering the hook, more of the topsides weight is applied to the base and the structure sinks to the sea-bed where it is secured by grouting. The upper supported section is then lifted to the desired height and the telescopic sections locked. Piling and drill casings, strings etc. may be lowered through the topsides into the hollow regions within the legs.

Abstract: Protective barrier consisting of at least two ballastable elements (3, 4) adapted to surround at least partially the work to be protected (1).The height of the individual elements is greater than the water depth. The elements comprise a connection device permitting the structural continuity of the elements after assembly. The protective barrier is entirely independent of the work to be protected. The positioning of the elements around the work is effected by means of a positioning system provided in the sea bed and/or the individual elements of the protective barrier.

Abstract: A submersible production storage barge and method for transporting and installing a jack-up rig in a body of water has the submersible production storage barge releasably secured to a jack-up rig while the jack-up rig and submersible production storage barge are towed as a unit to the desired offshore location.

Abstract: A gravity base structure for an offshore platform includes a caisson having a bottom slab, a top slab, and inner and outer concentric walls which extend between the bottom and top slabs, and partition walls that form a lattice structure of triangular prisms between the concentric walls, and a plurality of teeth elements which extend outwardly of the outer wall of the caisson for absorbing the force of iceberg impacts and transmitting such force to the caisson.

Abstract: A marine operations structure for use in arctic seas having steel/concrete composite ice walls positioned to permit multi-year ice ridges to be broken up with lower vertical forces imposed on the structure than heretofore possible. The structure provides for simultaneous contacting and fracturing of both surface ice floe and multi-year ice ridges by proportioning of the ratio of the annular dimension of a first sloped surface to the radius of the structure within the range of about from 0.15 to 0.30. The structure is fabricated by modular construction techniques which lowers total construction costs. The structure is in the form of a sixteen-sided polygonal sloped walled marine structure with internal ballast tanks for providing gravity founding of the structure on the sea floor. Modular drilling equipment is provided for and supported by the structure for use through two rectangular shaped moon pools extending vertical throughout the central core of the structure.

Abstract: A light-weight, modular drilling template. A template is constructed of light-weight tubular steel having ring stiffeners to provide adequate crush resistance to withstand collapse under hydraulic loading provided by water pressure at 1800 feet water depth. The template is constructed as a pod-receiving frame with separable pods that may be installed after the frame has been set on the seafloor and leveled. The individual pods may be fine tune leveled by means of adjustable jacking mechanisms that form part of the latching devices that secure the pods to the frame. A method for installing a foundation template subsequent to installing the drilling template is also described.