HK1200416B - A semi-submersible platform with a movable submergible platform for dry docking a vessel - Google Patents

Abstract

The present invention disclosed in this application relates to a semi-submersible platform with a landing bay. The landing bay has a movable platform that allows the docked vessel to be raised/ lowered from/ to a body of water. The landing bay also has a stabilizing mechanism for holding a docked vessel stable when the platform is in motion.

Description

Semi-submersible platform with movable submersible platform for dry docking of a vessel

Technical Field

The invention relates to a semi-submersible platform with a landing bay. More particularly, the present invention relates to a semi-submersible platform comprising a landing bay having a movable platform sized to fit beneath a docked seaworthy vessel, wherein the movable platform moves with the docked vessel between a submerged position and an exposed position. Still more particularly, the present invention relates to a semi-submersible platform having a landing bay, wherein the landing bay has a stabilizing mechanism for maintaining a docked vessel stable as the platform and vessel are moved between a submerged position and an exposed position using a lift mechanism.

Background

Over the past decades, offshore drilling platforms have been widely used by oil drilling companies. Of these platforms, mobile semi-submersible platforms are preferred over fixed platforms because they do not rely on the surface of the sea floor to achieve a stable foundation. Another advantage of semi-submersible platforms is that these mobile platforms can be easily moved from one drilling site to another.

Over the years, various logistical problems have arisen as drilling sites have moved further away from land. In particular, oil drilling companies face logistical problems in transporting personnel to and from the drilling site. Typically, helicopters are used to transport personnel. Helicopters may be equipped when the drilling site is located at about 150km offshore, however, using helicopters as a conventional large transportation means becomes inefficient when the drilling site is located at about 300km offshore. To address this logistics problem, it has been proposed to build accommodation platforms midway between the shore and the drilling site. In this way, helicopters can be equipped to transport people from shore to accommodation platforms and then, if necessary, to the drilling site beforehand. However, such solutions are still expensive and inefficient because helicopters still need to transport personnel from the accommodation platform to the drilling site. Furthermore, accommodation platforms must provide the helicopter with fuel filling equipment and, since the helicopter still needs to travel a considerable distance each day, may be fatigued, thereby increasing the incidence of accidents.

The use of aircraft carriers as mobile accommodation centers has been proposed. By utilizing such large vessels, large numbers of personnel can be transported, and typically these vessels will be able to provide accommodation for a large number of personnel. A disadvantage of using an aircraft carrier as a mobile accommodation center is that the aircraft carrier has a thin hull designed for speed rather than stability. Thus, when aircraft carriers are stationary, they tend to sway with the motion of the waves, making it almost impossible to land the helicopter. Furthermore, due to the lack of stability of a fixed aircraft carrier, boarding/disembarking of personnel from the vessel to the drilling platform would be a risky and dangerous act.

It has also been proposed to use high speed vessels to transport personnel to the drilling site. However, it becomes extremely difficult and dangerous for passengers to board and disembark from the vessel due to the harsh ocean conditions in which the drilling platform operates. In rough sea conditions, the challenge is to ensure that the vessel remains stable long enough to berth/dock the vessel for embarking/disembarking passengers or loading/unloading material.

At or near shore, under normal weather conditions, a high speed vessel may dock at a port or port dock to allow passengers on the vessel to easily board/disembark. Most port terminals have a containment structure formed therein for receiving a ship. The containment structure isolates the vessel from the open sea area, thereby mitigating wind, sea waves, and currents caused by relative motion between the port and the vessel. Additionally, to reduce congestion at the port, a vessel lifting device may be used to lift the vessel out of the water to make room for the incoming vessel. The watercraft lifting device that can be used is a dry dock lifting device, a partially submerged dry dock and/or a floating dry dock.

A dry dock lifting device is described in U.S. patent publication No.2009/0067961 a1, published 3, 12, 2009 under the name Luis Perez-Rodenas Espada. This publication discloses a raised quay berth (marina berth) having a series of upper and lower movable platforms supported on parallel transverse beams. These platforms are used for mooring and launching of the vessel. A docked vessel moored at the lower platform will be vertically lifted using a cable or sling system. These cables or slings are secured to the lower movable platform and parallel cross-beams for stability and even load distribution. The cross beams are in turn supported by four brackets firmly resting on the solid ground. The four cradles are anchored to the sea floor to provide a solid foundation for the dry dock lifting apparatus. In a preferred embodiment, two brackets are provided to support each beam. These carriers are in turn firmly anchored to the sea floor to ensure even load distribution.

Another type of dry dock lifting device is described in U.S. patent No.7,419,329B1, published on 2.9.2008 in the name of Craig Allen Tafoya. This publication discloses a portable marine lift for lifting and unloading a marine vessel. The disclosed design may be adapted for various vessel support devices, such as rail and/or cradle systems. The design has at least one movable platform and a plurality of lift pods attached to the platform. The legs of the lift car are firmly anchored to the sea floor, providing a stable foundation for the movable platform. A vessel moored at the platform can be lifted/lowered vertically by using conventional lifting units at each of the lifting pods. In a preferred embodiment, the lift pods evenly distributed around the movable platform ensure that the weight of the vessel can be evenly distributed to the seafloor via the anchored legs of the lift pods.

A buoyant marine lift system having an adjustable leveling system is disclosed in U.S. patent publication No.2008/0008528 a1, published by Kenneth e.hey and Bryce m.kolster, 1.10.2008. This publication discloses a floating vessel for lifting and lowering a vessel in the water. In the disclosed design, the marine lift has a plurality of gas tanks, each configured with an internal cavity for receiving and releasing pressurized air. Each tank is connected to a swing arm. When the tank receives sufficient pressurized air, the tank has sufficient buoyancy to lift the docked vessel out of the water. When the tank releases the pressurized air, this causes the swing arm to be released from the raised position, thus submerging the hull of the docked vessel into the water. This design can only be used in situations where the vessel is lifted in calm water conditions and in docking situations where the vessel is positioned close to land. Under severe sea conditions, such a design would not result in a stable "dry dock" device, since the design disclosed in this publication would not achieve the level of stability required to operate under severe sea conditions. Furthermore, such designs do not provide a guiding or stabilizing mechanism for safely guiding the vessel into the docking area under rough sea conditions and for keeping the vessel stable when lifting the vessel.

Therefore, for the purpose of realizing a mobile accommodation platform for oil drilling operations, the skilled person is constantly looking for ways to provide a mobile accommodation platform with mooring means in order to allow safe berthing of ships under unpredictable and/or rough sea conditions.

Disclosure of Invention

The above-mentioned and other problems in the art are solved and an advance in the art is made in accordance with the present invention. A first advantage of the semi-submersible with landing bay according to the present invention is that it provides a landing bay for a vessel to berth at an offshore drilling site. A second advantage of the semi-submersible platform according to the invention is that the landing bay has a movable submersible platform for lifting and lowering a moored vessel within the landing bay. A third advantage of the semi-submersible according to the invention is that the landing bay of the semi-submersible has a stabilizing mechanism for keeping the vessel stable when the vessel is close to the landing bay and when the vessel is lifted or lowered.

According to an embodiment of the invention, the semi-submersible platform according to the invention comprises a semi-submersible structure. The semi-submersible structure has a landing bay located therein. The landing bay is accessible through an opening through which a docked vessel can pass. The landing bay further comprises: a platform sized to fit under a docked vessel; a stabilizing mechanism for keeping the docked vessel stable; and a lift mechanism for moving the platform between the submerged position and the elevated position. In the submerged position, the platform is at a depth below the surface of the water and at a depth below the hull of the docked vessel. In the raised position, the platform is lifted out of the water to a predetermined height together with the docked vessel. The stabilizing mechanism maintains the level of the docked vessel as it is lifted, thereby preventing the vessel from tipping over and hitting the sides of the landing bay.

According to one embodiment of the invention, the semi-submersible structure includes a first semi-submersible hull and a second semi-submersible hull. The floats are positioned generally parallel to each other and spaced apart from each other to define an open area therebetween.

According to an embodiment of the invention, the semi-submersible structure further comprises a plurality of first support columns extending upwardly from the first semi-submersible hull, wherein the support columns are aligned substantially parallel to each other. A plurality of second support columns also extend upwardly from the second semi-submersible hull, and these support columns are also aligned generally parallel to one another.

According to an embodiment of the invention, the lifting mechanism is affixed to a portion of the first semi-submersible buoy and a portion of the second semi-submersible buoy.

According to an embodiment of the invention, the landing bay is located between the first end of the first semi-submersible buoy and the first end of the second semi-submersible buoy.

According to an embodiment of the invention, another platform spans a portion of the plurality of first support columns and a portion of the plurality of second support columns at the second end of the first semi-submersible buoy and the second end of the second semi-submersible buoy.

According to another embodiment of the invention, the stabilizing mechanism comprises a plurality of suction moorings having a first end affixed to the semi-submersible structure and a second end for attachment to the side of the docked vessel.

According to another embodiment of the invention, the lifting mechanism comprises a plurality of hydraulic lifts.

According to a further embodiment of the invention, the semi-submersible structure comprises guiding means for guiding the docked vessel through the opening in the landing bay.

According to an embodiment of the invention the guiding mechanism comprises a docking car arrangement.

According to an embodiment of the invention, the semi-submersible structure further comprises a boarding mechanism and a disembarking mechanism. The first ends of these devices are positioned adjacent to the semi-submersible structure and the second ends are positioned adjacent to the docked vessel. According to some embodiments of the invention, the boarding and disembarking mechanisms comprise a telescopic personnel access system.

According to one embodiment of the invention, the fixture further comprises a plurality of air bags affixed to the sides of the platform. These air bags are used to receive the hull of a docked ship.

According to an embodiment of the invention, the semi-submersible platform comprises a crew compartment, a helipad, and a lifeboat.

Drawings

The above advantages and features of the method and apparatus according to the present invention are described in the following detailed description and are illustrated in the accompanying drawings:

FIG. 1 illustrates a front view of a semi-submersible accommodation center having a movable semi-submersible platform according to an embodiment of the present invention;

FIG. 2 illustrates a view at the midship of a semi-submersible accommodation center having a movable semi-submersible platform according to an embodiment of the present invention;

FIG. 3 illustrates a plan view of an embodiment of a parking mechanism;

FIG. 4 illustrates a side view of an embodiment of a parking mechanism;

FIG. 5 shows an enlarged view of a movable semi-submersible platform having a plurality of bladders;

FIG. 6 illustrates the bottom of the float of the semi-submersible accommodation center according to one embodiment of the invention;

FIG. 7 illustrates a floating body deck of a semi-submersible accommodation center according to an embodiment of the invention;

FIG. 8 illustrates a discharge deck of a semi-submersible accommodation center according to an embodiment of the invention;

FIG. 9 illustrates a main deck of a semi-submersible accommodation center according to an embodiment of the invention;

FIG. 10 illustrates a top view of a semi-submersible accommodation center according to an embodiment of the invention; and

fig. 11 illustrates the exterior of a semi-submersible accommodation center according to an embodiment of the invention.

Detailed Description

The invention relates to a semi-submersible platform with a landing bay. More particularly, the present invention relates to a semi-submersible platform comprising a landing bay having a movable platform sized to fit beneath a docked seaworthy vessel, wherein the movable platform moves with the docked vessel between a submerged position and an exposed position. Still more particularly, the present invention relates to a semi-submersible platform having a landing bay, wherein the landing bay has a stabilizing mechanism for stabilizing a docked vessel as the platform and vessel are moved between a submerged position and an exposed position using a lift mechanism.

Semi-submersible platform 100 shown in fig. 1 is a semi-submersible platform with a landing bay, according to an embodiment of the present invention. Semi-submersible platform 100 includes buoys 120 and 125. There is an opening between the first ends of floats 120 and 125. Which allows the vessel to enter landing bay 105 located within semi-submersible platform 100. Fig. 1 shows landing bay 105 located within semi-submersible 100. In this view, vessel 110 is shown moored within landing bay 105. Platform 115 is a movable platform located within the landing bay, and platform 115 is positioned between buoyant bodies 120 and 125. Platform 115 is arranged such that platform 115 fits beneath vessel 110 when vessel 110 is docked within landing bay 105. In an embodiment, the platform 115 may comprise a planar truss structure. Those skilled in the art will recognize that the platform 115 may comprise other types of planar structures without departing from the present invention.

In operation, a portion of semi-submersible platform 100 will be submerged below water level 130. Vessel 110 enters landing bay 105 through an opening located between floats 120 and 125. As shown in fig. 1, when vessel 110 is moored within landing bay 105, vessel 110 will be above submerged platform 115. When vessel 110 is positioned within landing bay 105, the structure of landing bay 105 will shield vessel 110 from external elements, thus allowing vessel 110 to dock safely. Once vessel 110 is safely moored within landing bay 105, platform 115 will move from a submerged state to an exposed state. This causes platform 115 to come into contact with the hull of vessel 110. When the platform 115 is lifted out of the water, the platform 115 also lifts the vessel 110 out of the water. Once the moored vessel 110 has been lifted out of the water, the boarding/disembarking process and/or the loading/unloading process can be safely carried out, since the vessel 110 is now in an extremely stable position. When vessel 110 is in such a position, vessel 110 will be unaffected by external factors, such as strong winds and any other external factors associated with rough sea conditions, because the structure of semi-submersible platform 100 will effectively act as a barrier for vessel 110. Further, once vessel 110 has been lifted out of the water, vessel 110 becomes immune to rough sea conditions because vessel 110 is no longer in contact with the sea. Unlike the prior art, where the vessel is only lifted out of the water under calm sea conditions, semi-submersible 100 is capable of lifting vessel 110 out of the water under rough sea conditions.

The parameters of influence of the motion of semi-submersible platform 100 are considered when designing semi-submersible platform 100. The design characteristics that affect motion of semi-submersible platform 100 are the shape and size of floats 120, 125. In particular, buoys 120 and 125 have been designed to minimize motion of semi-submersible platform 100. Additionally, the structural columns extending upward from pontoons 120 and 125 (see FIG. 4) are also shaped and sized to minimize motion of semi-submersible platform 100. The metacentric height of semi-submersible platform 100 is designed to be as large as possible to reduce the motion of semi-submersible platform 100. Furthermore, the waterplane area of semi-submersible platform 100 is minimized, thus reducing resonance between wave motion and the natural frequency of semi-submersible platform 100.

Additionally, to reduce heave motions of semi-submersible platform 100, floats 120 and 125 are submerged below water level 130. These features provide semi-submersible platform 100 with the necessary strength and air gap to resist environmental loads caused by wave motion when semi-submersible platform 100 is operated in offshore drilling conditions. Thus, semi-submersible platform 100 has an inherent heave period in the range between 18 seconds (0.35rad/sec) to 22 seconds (0.28 rad/sec). At an offshore drilling site, the wave excitation period is typically between 8 seconds (0.79rad/sec) and 15 seconds (0.42 rad/sec). Heave motion of semi-submersible platform 100 is reduced because the natural frequency of platform 100 does not resonate with the excitation frequency of the waves. The mismatch between the natural frequency of semi-submersible platform 100 and the excitation of the waves results in a semi-submersible platform that has very low heave motions and remains stable at all times.

In one embodiment, semi-submersible platform 100 is used as an offshore accommodation hub. Semi-submersible platform 100 is suitable for use as a mobile accommodation center because the transfer of personnel to and from the accommodation center is facilitated through the use of landing bay 105. Landing bay 105 allows a personnel-carrying vessel to safely dock within semi-submersible 100. An approaching vessel will enter landing bay 105 through an opening located between floats 120 and 125. Once safely docked within landing bay 105, platform 115, submerged at the bottom of landing bay 105, is lifted out of the water. This action in turn lifts the moored vessel from the water only to a predetermined height. In this embodiment, the vessel is lifted to a predetermined disembarking/embarking height. A telescoping personnel access system (not shown) located on either side of the accommodation center may then extend towards the docked vessel. Personnel can then easily board or disembark from a docked vessel. The telescopic personnel access system may comprise a self-stabilizing telescopic gangway which may actively compensate for all vessel movements to ensure that the transport of personnel to and from a docked vessel is done in a safe and efficient manner. Specific details of telescoping personnel access systems are known in the art and have been omitted for the sake of simplicity. Semi-submersible platform 100 may also be provided with crew compartments and crew facilities when semi-submersible platform 100 is used as an offshore accommodation hub. This allows a large number of people to remain on semi-submersible 100 for a long period of time.

As can be seen in fig. 1, the width of the opening of landing bay 105 is slightly wider than the width of vessel 110. Thus, to avoid vessel 110 from striking semi-submersible 100 when vessel 110 is near landing bay 105, a securing mechanism is used to hold vessel 110 steady while vessel 110 is near landing bay 105. Such a securing mechanism is shown in fig. 2. In one embodiment, mooring systems 205 and 210 positioned within landing bay 105 are used as securing mechanisms. Mooring systems 205 and 210 may include suction cups and associated suction control devices operable to secure the suction cups relative to the vessel. For simplicity, only the operation of the mooring system 205 is disclosed. Those skilled in the art will recognize that mooring system 210 may operate similarly to mooring system 205. In operation, as vessel 110 approaches landing bay 105, a suction pad (not shown) from mooring system 205 will be separated from landing bay 105. The suction pad will be connected to the mooring system 205 via a cable or chain (not shown). The suction pad would be secured to the side of the approaching vessel 110. Similarly, suction pads from mooring system 210 would be secured to the opposite side of the approaching vessel 110. Mooring systems 205 and 210 will automatically adjust the tension and/or length of the lines attached to the suction pads as vessel 110 approaches landing bay 105. In this way, vessel 110 will be able to safely pass through the opening into landing bay 105 with the aid of mooring systems 205 and 210.

Under rough sea conditions, when vessel 110 approaches landing bay 105 to dock, vessel 110 will have difficulty maneuvering itself safely into landing bay 105. To overcome this obstacle, a docking mechanism (not shown) may be used to securely pull vessel 110 through the opening and into landing bay 105. In an embodiment of the invention, the docking mechanism may comprise a docking car arrangement. The docking car arrangement comprises two rails on each side of the semi-submersible structure. A winch with a cable or chain is fixed on each of these rails. In operation, these cables or chains are securely fastened to vessel 110. The cable or chain is then hauled by the winch, pulling vessel 110 toward landing bay 105. Mooring systems 205 and 210 may also be used to assist in holding vessel 110 steady as vessel 110 passes through the opening into landing bay 105.

In another embodiment, the docking mechanism may comprise a rigid yoke structure having arms extending outwardly toward the vessel, as shown in fig. 3. Rigid yoke structure 300 has a generally V-shape or U-shape with curved arms 305 and 306. The rotatable member 307 is secured at the intersection of the curved arms 305 and 306. An outwardly extending arm 310 is connected at one end to the rotatable member 307 and at the other end to the rotatable member 320. The rotatable members 307 and 320 may rotate about 360 degrees axes thus allowing a rigid yoke structure to assist in the stabilization of the docked vessel. The rotatable member 320 is connected to the clasp 315 at the other end. Clasp 315 is used to lock or fasten to vessel 110 when vessel 110 is near landing bay 105.

In operation, curved arms 305 and 306 are secured to tracks located on both sides of landing bay 105. As vessel 110 approaches landing bay 105, rigid yoke structure 300 moves from landing bay 105 outwardly along the track. Clasps 315 of outwardly extending rigid yoke structure 300 are then secured to vessel 110 upon impact with docked vessel 110. Vessel 110 is automatically aligned with landing bay 105 due to the position of arm 310 on rigid yoke structure 300. Rigid yoke structure 300 then pulls vessel 110 into landing bay 105. It should be noted that the two opposite ends of the rigid yoke structure are affixed with bearings (not shown) that allow the rigid yoke structure to compensate for yaw and roll of vessel 110. Rotatable members 307 and 320 also assist in the compensation of yaw and sway of vessel 110 while vessel 110 is docked. Fig. 4 shows a side view of a rigid yoke structure 300. Those skilled in the art will recognize that fastening member 315 may comprise other fastening or securing means without departing from the present invention.

Mooring systems 205 and 210 assist in stabilizing vessel 110 within landing bay 105, thereby preventing vessel 110 from striking the sides of landing bay 105. Additionally, mooring systems 205 and 210 help to keep vessel 110 stable as vessel 110 is lifted by platform 115. However, having only mooring systems 205 and 210 is not sufficient to be able to keep vessel 110 stable when platform 115 is moved from the submerged position to the elevated position. When this occurs, the upper surface of platform 115 will be in contact with the hull of vessel 110. Since the hulls of most vessels do not provide a flat stable surface, securing means must be provided to ensure that the vessel 110 does not tip over when the vessel 110 is lifted out of the water or lowered into the water. This may be accomplished by introducing an air bag 225 between the hull of vessel 110 and the upper surface of platform 115. Bladder 225 acts as a cushion for the hull of vessel 110, encompassing the hull of vessel 110 when platform 115 is raised, thus keeping vessel 110 stable. One exemplary arrangement of the balloon 225 is disclosed in fig. 5. Those skilled in the art will recognize that the balloon 225 may be arranged in different configurations and is not limited to the arrangement shown in fig. 5. In fig. 5, the bladders 225 are arranged in rows to allow the weight of the docked vessel 110 to be evenly distributed throughout the platform 115.

Referring back to fig. 2, lift mechanisms 215 and 220 located within landing bay 105 are used to raise or lower platform 115. In one embodiment, the lifting mechanisms 215 and 220 may comprise hydraulic lifts. These hydraulic lifts are connected to hydraulic cylinders which are fixed to the sides of the semi-submersible structure. These hydraulic cylinders are designed so that they can withstand the total weight of the platform 115 and the vessel 110 with the personnel on the vessel.

The total load of vessel 110, platform 115 and personnel will be evenly distributed between the four hydraulic cylinders. Those skilled in the art will recognize that other devices or apparatus may be used as the lift mechanism without departing from the present invention. In operation, semi-submersible platform 100 will be moored at an offshore location at an operating draft. The operational draft of semi-submersible platform 100 is the vertical distance between the bottom surface of semi-submersible platform 100 floating in the water and water level 130. The additional weight of vessel 110 on platform 115 will result in an increase in the operating draft. The additional weight of vessel 110 on platform 115 is included in the design of semi-submersible platform 100.

In another embodiment, platform 115 may be provided with heave compensation mechanisms to dampen movement of semi-submersible platform 100 due to the motion of the rolling waves. The heave compensation mechanism incorporated in the platform 115 may comprise a drill string compensation device. One end of the drill string compensator may be connected to the bottom of the platform 115 and the other end of the drill string compensator may be anchored to the sea floor. The heave compensation mechanism coupled to the platform 115 ensures smooth operation of the platform 115 by minimizing downtime events in severe weather conditions. The heave compensation mechanism will also enhance the level of accuracy of the platform 115 when the platform 115 is lifted from the submerged position to the raised position.

As previously mentioned, in prior art designs, the disclosed dry dock docks or the disclosed watercraft lifting apparatus may be used for applications in calm sea, shallow waters, or dry land. These limitations are inherent in the previously disclosed designs because these designs do not have a heave compensation system that allows a vessel to be combined with a lifting apparatus to lift another vessel in deep water or under rough offshore conditions typically associated with oil drilling sites. The present invention addresses these problems by utilizing the heave compensation system of semi-submersible platform 100. The different levels of the semi-submersible platform are set up as follows. Fig. 6 shows the bottom level of the semi-submersible platform, which is a float level 600. Together, buoyant bodies 125 and 120 form a level area for buoyant body level 600. Buoys 120 and 125 are generally parallel to each other and are connected by connecting stringers 605. Buoys 120 and 125 include waterproof ballast that contributes to the buoyancy of semi-submersible platform 100. Semi-submersible platform 100 may be raised or lowered by adjusting the ballast of floats 120 and 125. In operation, floats 120 and 125 are submerged below water level 130, thereby increasing the draft of semi-submersible platform 100. This promotes stability of platform 115 and docked vessel 110 when platform 115 is lifted from a submerged position to a raised position.

Structural columns 610, 615, 620, 625, 630 and 635 extend upward from pontoons 120 and 125. Structural columns 610, 615, 620, 625, 630 and 635 are spaced apart from each other to ensure that buoys 120 and 125 can support a load. Structural columns 610, 615, 620, 625, 630 and 635, having a larger diameter, rise upward from buoy level 400 to above the surface of the ocean waves. Structural columns 610, 615, 620, 625, 630 and 635 are used to support the load of semi-submersible platform 100. When semi-submersible platform 100 is configured for offshore operations, buoy level 600 will be submerged below the water surface. The float level 600 is below the level of the ocean waves to reduce the response of the platform caused by the ocean waves.

The level above the float level 600 is the landing level 700. Figure 7 shows a buoyant hull deck 700. A buoyant deck 700 including platform 115 is also submerged under the ocean waves. For purposes of illustration, vessel 110 is shown in this figure to illustrate the positioning of vessel 110 at buoy deck 700 relative to platform 115. Fig. 7 also shows structural columns 610, 615, 620, 625, 630 and 635, which are evenly spaced on buoys 120 and 125 to achieve a stable and even load distribution on the buoys.

Fig. 8 shows the landing deck level 800 of semi-submersible platform 100. The figure shows an opening (represented by an arrow) into landing bay 105. A vessel approaching landing bay 105 will enter via an opening between structural columns 620 and 625, which are located on buoys 120 and 125, respectively. Those skilled in the art will recognize that the distance between buoys 120 and 125 may vary depending on the width of the vessel to be docked within landing bay 105 without departing from the present invention.

Fig. 9 shows the main deck of the semi-submersible platform 100. The structural columns 610, 615, 630, and 645 support the load of the deck 905. Deck 905 may be used to support production facilities, generators, and crew accommodation. Those skilled in the art will recognize that the interchanging of different modules of equipment and facilities may be made to accommodate the particular requirements of semi-submersible platform 100 without departing from the present invention.

Fig. 10 shows a top view of an embodiment of the invention, and fig. 11 shows an outboard view of an embodiment of the invention. In these views, crew quarters 1005 may be located between helicopter tarmac 1010. Lifeboats 1015 are strategically positioned around semi-submersible platform 100 for use by crew of semi-submersible platform 100 in emergency situations. A crane 1020 is located above the structural column 620 and may be used to load/unload cargo from the deck 905. Deck 905 is designed in an open frame manner, allowing modules 1005, 1010, and 1015 to be easily removed and replaced by other modules to change the functionality of semi-submersible platform 100 from a lodging center to a gas generation unit depending on the desired field of operation.

Semi-submersible platform 100 is advantageous over prior art dry dock installations because semi-submersible platform 100 is provided with landing bay 105 having movable semi-submersible platform 115 that is capable of lifting or lowering other vessels under a variety of ocean conditions. As previously mentioned, vessel 110 docked above platform 115 may be raised or lowered by lifting mechanisms 215 and 220. Furthermore, the lifting and lowering of vessel 110 is done in a stable and robust manner, since the additional weight of the lifted vessel 110 is absorbed by the design of semi-submersible platform 100.

The foregoing describes a semi-submersible platform having a movable semi-submersible platform that is capable of lifting a vessel under a variety of ocean conditions. It is anticipated that one skilled in the art can and will design alternative embodiments of the invention as set forth in the following claims.

Claims (18)

1. A semi-submersible platform, comprising:

a semi-submersible structure; and

a landing bay within the semi-submersible structure, the landing bay accessible to a vessel passing through an opening through the semi-submersible structure, wherein the landing bay comprises:

a platform sized to fit under a docked vessel and movable between a submerged position in which the platform is below the water surface in the landing bay to a depth that allows the docked vessel to float on the platform, and an exposed position in which the platform holds the docked vessel out of the water;

a lift mechanism for moving the platform between the submerged position and the exposed position; and

a stabilizing mechanism for maintaining the docked vessel in a horizontal position in response to movement of the platform from the submerged position to the exposed position, wherein the stabilizing mechanism comprises a plurality of suction mooring devices having a first end affixed to the semi-submersible structure and a second end for attachment to a side of the docked vessel.

2. The semi-submersible platform of claim 1 wherein the semi-submersible structure comprises:

a first semi-submersible hull located on a first side of the semi-submersible structure; and

a second semi-submersible hull located on a second side of the semi-submersible structure, wherein the first semi-submersible hull and the second semi-submersible hull are substantially parallel and spaced apart to define an open area between the first semi-submersible hull and the second semi-submersible hull.

3. The semi-submersible platform of claim 2 wherein the semi-submersible structure further comprises:

a plurality of first support columns extending from a top side of the first semi-submersible hull, wherein the plurality of first support columns are aligned substantially parallel to each other; and

a plurality of second support columns extending from a top side of the second semi-submersible buoy, wherein the plurality of second support columns are aligned substantially parallel to each other.

4. The semi-submersible platform of claim 2 wherein the lift mechanism is affixed to a portion of the first semi-submersible hull and a portion of the second semi-submersible hull.

5. The semi-submersible platform according to claim 3 wherein the landing bay is located between the first end of the first semi-submersible hull and the first end of the second semi-submersible hull.

6. The semi-submersible platform of claim 5 further comprising:

a further platform spanning a portion of the plurality of first support columns and a portion of the plurality of second support columns at a second end of the first semi-submersible buoy and a second end of the second semi-submersible buoy, wherein the further platform spans the open area between the first semi-submersible buoy and the second semi-submersible buoy.

7. The semi-submersible platform of claim 1 wherein the lift mechanism comprises:

a plurality of hydraulic elevators.

8. The semi-submersible platform of claim 1 wherein the semi-submersible structure further comprises:

a guide mechanism for guiding the docked vessel through the opening through the semi-submersible structure.

9. The semi-submersible platform of claim 8 wherein the guide mechanism comprises a docking car device.

10. The semi-submersible platform of claim 8 wherein the guide mechanism comprises a rigid yoke structure.

11. The semi-submersible platform of claim 1 wherein the semi-submersible structure further comprises:

a disembarking mechanism having a first end adjacent to the semi-submersible structure and a second end positioned adjacent to the docked vessel.

12. The semi-submersible platform of claim 11 wherein the departure mechanism comprises a telescoping personnel access system.

13. The semi-submersible platform of claim 1 wherein the semi-submersible structure further comprises:

a boarding mechanism having a first end adjacent the semi-submersible structure and a second end positioned adjacent the docked vessel.

14. The semi-submersible platform of claim 13 wherein the boarding mechanism comprises a telescoping personnel access system.

15. The semi-submersible platform of claim 1 wherein the landing bay further comprises a fixture comprising:

a plurality of airbags affixed to a first side of the platform for receiving the docked vessel.

16. The semi-submersible platform according to claim 1, further comprising:

a crew compartment.

17. The semi-submersible platform according to claim 1, further comprising:

a helicopter apron is disclosed.

18. The semi-submersible platform according to claim 1, further comprising:

a lifeboat.