US3306052A

US3306052A - Floatable structure and method of operating same

Info

Publication number: US3306052A
Application number: US304590A
Authority: US
Inventors: Kawasaki Masasuke
Original assignee: DIRECTO CORP
Current assignee: DIRECTO CORP
Priority date: 1963-08-26
Filing date: 1963-08-26
Publication date: 1967-02-28
Anticipated expiration: 1984-02-28
Also published as: NL6409902A; ES303480A1; GB1077738A; DE1484559A1; BE652206A

Description

1967 MASASUKE KAWASAKi 3,306,052

FLOATABLE STRUCTURE AND METHOD OF OPERATING SAME 5 Sheets-Sheet 1 Filed Aug. 26, 1963 A Masai/n49 flowarah INVENTOR. MW b By gal .m

ATTO/P/VEVJ 1967 MASASUKE KAWASAKI 3,396,052

FLOATABLE STRUCTURE AND METHOD OF OPERATING SAME Filed Aug. 26, 1963 5 Sheets-Sheet 2 M010: 0/46 //a WO'J 0h INVENTOR.

2 1967 MASASUKE KAWASAKI 3,306,052

FLOATABLE STRUCTURE AND METHOD OF OPERATING SAME NVENT R 5 Sheets-Sheet 3 Filed Aug. 26, 1963 Feb 1967 MASASUKE KAWASAK! 3,306,052

FLOATABLE STRUCTURE AND METHOD OF OPERATING SAME Filed Aug. 26, 1963 5 Sheets-Sheet 4 Mar 0: aka flan/cw 0/40 INVENTOR.

1967 MASASUKE KAWASAKI 3,

FLOATABLE STRUCTURE AND METHOD OF OPERATING SAME Filed Aug. 26, 1963 57001455 POI/770 5 Sheets-Sheet 5 McrJaJuA e /(0W0J0%/ INVENTOR. d 0mm an LA BY g P.

ATTOKF/VEVJ United States Patent Oil-ice 3,36,,fl52 Patented Feb. 28, 1957 3,306,052 FLQATAELE STRUCTURE AND METHOD OF OPERATING SAME Masasulre Kawasaki, Slideil, La., assignor, by mesne assigmeuts, to Eireeto Corporation, Slideli, 1.21., a corporation of Texas Filed Aug. 26, 1963, Ser. No. 304,590 15 Claims. (Cl. 61--46.5)

The present invention relates generally to floating bargeplatforms for use in marine operations to provide a stable platform with relation to the floor of the body of water on which the device is to operate. More specifically, the present invention relates to a barge-platform which is designed to float when it is not firmly fixed in location for drilling.

Prior to the present invention much of the offshore drilling for oil and gas has been accomplished from platforms which had legs that telescoped downwardly to the floor of the body of water or from platforms which have been erected on piling driven into the ocean floor. These prior structures have had vertically extending support legs. Such prior structures have had disadvantages in that they either had to be constructed on the drilling site or if they were of the floating platform type they have been extremely bulky and difficult to tow to the desired location, subject to overturning during movement to the desired location, and they have required extensive equipment for setting the platform on the ocean floor. Therefore, the primary object of the present invention is to provide a floating platform barge which is self-erecting and provided with support legs which extend downwardly and outwardly for stability of the platform when anchored.

Another object of the present invention is to provide a floating platform in which most of the structure is relatively close to the water when in towing position. A further object of the present invention is to provide a floating drilling platform for marine operation having hinged legs which can be actuated into drilling position by adding ballast to the compartments in the legs. Another object of the present invention is to provide a floating platform for drilling which may be erected in position for drilling by shifting ballast within the structure. A still further object of the present invention is to provide a marine drilling platform having downwardly and outwardly extending legs adapted to rest on the floor of the body of water in which the platform is desired to be positioned. Still another object of the present invention is to provide a marine drilling platform with hinged legs adaptable for positioning at a variety of angles extending downwardly and outwardly from the platform.

Another object of the present invention is to provide a barge platform having legs which may be ballasted wherein the legs are hydrostatically stable at an inclination during ballasting and de-ballasting of the structure to provide stability of the structure as a whole.

Another object of the present invention is to provide a barge platform having a plurality of legs two of which rotate from a parallel towing position for floating to an inclined position having an angle of divergence therebetween and such rotation is caused by a controlled ballasting of compartments in the legs.

A further object of the present invention is to provide a marine platform barge having buoyant legs which may be pivoted into a downwardly and outwardly extending position by ballasting of the legs and de-ballasting of the platform.

These and other objects of the present invention are more fully described in respect to the drawings wherein:

FIGURE 1 is a perspective view of the platform of the present invention with the legs down.

FIGURE 2 is a side elevation view of the platform of the present invention in floating position or towing position and with the legs up and illustrating such position with relation to the water level.

FIGURE 3 is a side elevation view of the platform of the present invention with the legs in the downward position and illustrating the floating of the platform in this position with relation to the Water level.

FIGURE 4 is another side elevation of the platform of the present invention in position on the floor of the body of water and illustrating the position with relation to the water level.

FIGURE 5 is a detail side elevation view of the platform of the present invention in floating position with the legs up.

FIGURE 6 is a partial sectional View taken along line 6-6 in FIGURE 5.

FIGURE 7 is a schematic view of one leg illustrating the compartments, piping, valving and pumps contained within the leg.

FIGURE 8 is a schematic illustration of the platform barge of the present invention having an inclined pivot of the rear legs and showing the upper position of the legs in solid lines and the lower position of the legs in dashed lines.

As shown in FIGURE 1, platform 1 is supported by

rear legs

2 and 3 and by front legs 4 and 5. Drilling tower 6 is positioned on drilling platform 7 which is fixed- 1y secured to the front edge of platform 1. Platform 1 may be of any suitable construction, but the preferred form should be compartmented and provided with suitable ballasting and deballasting pumps and controls for the reasons hereinafter more fully explained.

Rear legs

2 and 3 are suitably connected by horizontal braces S and 9 and by cross braces 10 and 11. Each of

legs

2, 3, 4 and 5 is composed of two tubular sections (12 and 13, 14 and 15, 16 and 17, and 18 and 19 respectively) joined at their outer extremities by welding to form each leg, by

pivot arms

20, 21, 22 and 23 respectively between each of the respective tubular sections of the legs and by

braces

24, 25, 26 and 27 respectively as shown. As best shown in FIGURE 6,

tubular sections

17 and 19 of front legs 4 and 5 are joined together at their inner extremities and are secured to platform 1 by pivot 28. If it is desired that legs 4 and 5 move independently of each other for reasons hereinafter more fully explained, then

tubular sections

17 and 19 shoud not be joined as shown in FIG- URE 6, but should be formed to allow movement of one with respect to the other. It should be noted that legs 4 and 5 are not joined to each other by bracing as are

legs

2 and 3. Suitable bracing may be used if

tubular sections

17 and 19 are to be joined and if such bracing does not interfere with the particular marine operation for which the device is to be used. When the device is to be used for drilling, care must be taken in bracing legs 4 and 5 together, particularly

sections

17 and 13, since such bracing might, in the positions to which the legs are lowered to support platform 1, interfere with the drilling operations. Pivot 28 comprises pintle 29 extending through the joined portions of

sections

17 and 19, through lugs 30 which depend from the lower surface of platform 1 and through

arms

22 and 23 whereby legs 4 and 5 are pivotally secured to platform 1.

Rear legs

2 and 3 are also pivotally secured to the lower surface of platform 1 by pivots 31 and 32 respectively. Pivot 31 includes pintle 33 extending through tubular section 13 of leg 2, through lugs 34 depending from platform 1 and through arm 20. Pivot 32 includes pintle 35 extending through tubular section 15 of leg 3, through lugs 36 depending from platform 1 and through arm 21.

Bolting plate 37 is secured as by welding to the inner nd of section 12 of leg 2 and is designed to pass through lot 38 in platform 1 when leg 2 is being lowered. Sim-iirly section 14 of leg 3 is provided with bolting plate 39 lhlCh is received in slot 46, section 16 of leg 4 is proided with bolting plate 41 which is received in slot 42 nd section 18 of leg 5 is provided with a similar bolt- Jg plate (not shown) which is received in slot 43. The olting plate for section 18 of leg 5 is not shown because is hidden in all of the drawings behind the other porions of the structure, but is of similar construction to iolting plate 41 except that it is reversed. Belting plates '7, 39, 41 and the bolting plate for leg 5 are all provided vith a plurality of holes as shown for receiving suitable tolting at any desired position of the legs to lock the iosition of the legs.

Legs

2 and 4 are provided with second bolting plates 37a and 41a secured to

sections

13 and 17 respectively, .s best shown in FIGURE 1, and legs 3 and 5 are proided with similar bolting plates (not shown). Such secnd bolting plates are provided to lock the legs in their owing position.

The leg shown in FIGURE 7 is typical of the interior :onstruction of all of the legs of the present invention. or purposes of clarity it is identified as leg 2. The outer uncture of

sections

12 and 13 is formed into compartnent 44 by welding partition 45 into section 12 and parition 46 into section 13.

Partitions

47, 48 and 49 are velded into section 12 forming compartments 5t), 51, 52 md 53.

Partitions

54, 55 and 56 are welded into section

l3 forming compartments

57, 58, 59 and 60. The outer :nd of leg 2 is closed by plate 61 which is welded therein to complete compartment 44. It should be noted that he position of plate 61 is such that it is designed to rest 7n the bottom of the body of water in which platform l is to be located and has the proper angle with respect 0 leg 2 so that it will be substantially horizontal when eg 2 is positioned in its supporting position. Also, all )f the partitions in

sections

12 and 13 should be completely seal-welded, thereby forming Watertight compartnents to prevent leakage of ballast between compartments.

Pump 62 is positioned within compartment and is provided with inlet 63 having valve 64 therein to control the fiow of water to pump 62. Pump 62 is shown to be powered by motor 65. It is preferred that motor 65 be electric for simplicity of control. The wiring and switches controlling motor 65 are not shown but are well known and any suitable control system may be used without departing from the principles of the present invention. Inlet 63 is connected to a water source which is to be used as ballast. Obviously, the body of water in which platform 1 is to be located is usually the best source of water for ballast unless the water contains such corrosive compounds as would make the ballast system (hereinafter more fully described) inoperative. In such event, a suitable source of water or other liquid ballast should be provided. The ballast system is designed to utilize normal sea water, and care is taken in the selection of materials for the pumps, valving and lines that normal sea water does not cause such corrosion as would render the ballast system inoperative.

Pump discharge 66 extends from pump 62 and acts as a manifold to

valves

67, 68 and 69. Line 70 connects from valve 67 into compartment 59, line 71 connects from valve 68 into compartment 58 and line 72 connects from valve 69 into compartment 57.

Vent lines

73, 74 and 75 are provided from

compartments

57, 58 and 59 respectively.

Discharge lines

76, 77 and 78 extend from compartments 57, 5S and 59 respectively to valves 7?, 80 and 81 respectively. Manifold 81a extends from

valves

79, 80 and 81 to the inlet of pump 82. Control rod 33 is shown extending from compartment 60 to valve 79 and is illustrative of the remote control provided for

valves

79, 80 and 81. Any suitable remote control may be provided to control the valves used in the ballasting system of the present invention without departing from the invention such as providing the valves with electric actuators and controlling the valves electrically.

Pump 82 is powered by motor 84 which is of a suitable type for remote control. Pump discharge line 35 extends upwardly through section 12 and out of compartment 53 and is controlled by valve 36. The water being used for ballast when discharged through line 85 will be discharged into the body of water in which platform 1 is located. Unless sufficient reserve buoyancy is provided in the structure of the present invention, ballast liquid should not be stored in the structure when it is discharged from the legs even though it is to be separately stored because of the unsuitability of the water in which the structure is located.

However, as hereinafter more fully explained, ballast is preferred to be stored in the compartments of the platform 1 and then pumped by a suitable pump 201 into the legs and returned from the legs to assist in the control of the positioning of the legs with respect to platform 1.

Discharge lines

87, 88 and 89 extend from compartments 5t 51 and 52 respectively to

valves

99, 91 and 92 respectively. Manifold 3 extends from

valves

90, 91 and 92 to the inlet of pump 82. Control rod 94 or other suitable control device extends from compartment 53 to

valves

90, 91 and 92.

Vent lines

95, 96 and 7 extend from

compartments

50, 51 and 52 respectively to the exterior of compartment 53 to provide suitable venting of the chambers during the filling or emptying of the respective compartments.

A filling system for

compartments

50, 51 and 52 is not shown in FIGURE 7 but is contemplated. It is pre ferred that pump 62 be used for the ballasting of

com partments

50, 51 and 52 and either additional valves should be provided on pump discharge 66 to direct the ballast water individually to

compartments

50, 51 and 52, or a separate filling pump and valving similar to that shown in compartment 60 should be provided in compartment 53.

In the preferred form of the present invention, each of the

compartments

50, 51, 52, 57, 53 and 59 should be connected to the filling and discharge of the ballast system so that they may be individually controlled. It is possible to modify such a ballast system whereby the filling and discharge of compartments is accomplished with a single set of controls and pumps merely by interconnecting the compartments, i.e., connecting compartment 50 to compartment 57, connecting compartment 51 to compartment 58, and connecting compartment 52 to compartment 59 but care must be taken with the design of such a system to assure that the position of the legs may be accurately controlled by the ballasting and deballasting. Individual control of the ballasting of each of the compartments is preferred. It is also within the scope of the present invention to provide individual ballasting of compartment 44 with suitable controls for filling, discharge and venting, but this is not shown in order that the control system is clearly illustrated with regard to the other compartments. It should be clearly understood that because of the extremely large sizes involved in the tubular sections of the respective legs that the enclosing of the valves, pump and motor within compartment 44 would iequire a relatively small amount of space with respect to the actual size of compartment 44. Alternately, compartment 44 may be filled with ballast water if the valves, pump and the motor are of such construction that they will operate properly when they are submerged in ballast water within compartment 44.

Prime concern in ballast and deballasting is stability of the barge. Direct flooding of the compartments in the legs through sea chests or bypassing pumps should not be used. Such direct flooding will leave air in the compartment exposed to additional pressure due to depth below the water surface and thus subject to volumechanges beyond human control and therefore will lead to erratic control of ballasting or deballasting which could result in upsetting or severe tilting of the barge.

Another method for ballasting and deballasting is to control the ballast water in the platform 1. As previously mentioned the platform 1 is constructed to contain ballast. Referring to FIGURE 2, the platform 1 could be heavily loaded with ballast water. At site the platform 1 is made lighter by deballasting with pump 201 and suitable piping in a similar fashion as previously explained for the legs. Then the platform 1 will emerge out of water while the legs are being lowered into water. The process should be continued until the legs reach desired depth. To be moved from the site the platform should be ballasted after the legs are loosed from bottom of the sea and the

bolting plates

37, 39, 41, etc., are unbolted.

This method of ballasting and deballasting the platform will provide a better control. However, if such method is used, the whole structure would normally be larger than otherwise contemplated. It is preferred that a compromise of the two methods will be beneficial in actual application depending upon the other limitations such as depth and range of water to be covered, dead weight to be carried, and limitation of water channel.

Stability of tubular members submerged in water is a delicate balance as may be readily understood by adding a small amount of water to an ordinary pop bottle. The bottle will not float at an inclined angle but will immediately take a substantially vertical position in the water.

For positive control, each leg is made up of two tubular columns formed in V-shape. Such leg structure also provides easy, positive and safe control, and also, as a byproduct, the necessary strength. Each leg must be stable by itself within the surface of its rotation, even if all the pins and bolts are loosened. As well known in naval architecture, the design and operation will be such as to keep the GM of each leg positive at all times. The V-shape indicated above which keeps a wide water plane between the ballasted compartment and the compartment full of air, is the preferred design to accomplish the above.

Positive GM as used herein indicates that the vessel considered is stable, i.e., that center of gravity with or without ballast should be below the metacenter at corresponding loads assumed at the hinge resulting from the support of platform 1.

As shown in FIGURE 8 the mounting of the

rear legs

2 and 3 on an inclined pivot rather than the horizontal pivots 31 and 32 shown in the other figures can position

legs

2 and 3 in parallel relationship to each other when they are in towing position and still provide a substantial angle of divergence when

legs

2 and 3 are in the submerged or support position. The inclination of these pivots is shown to be the angles designated a in FIG- URE 8. These two positions establish a plane in which the legs rotate and the pivot will extend perpendicular to such plane of rotation. This pivot is easily established by proper placement of the legs below platform 1 and drilling such legs and the pintle receiving lugs to receive a pintle so that the centerline of the pintle coincides with the desired pivot.

The placement of the device of the present invention is clearly explained with reference to FIGURES 2, 3 and 4. FIGURE 2 shows platform 1 and

legs

2, 3, 4 and 5 in the towing position, floating on the water surface 98. In this position the structure may be towed to the location where it is to be set. If considerable distances are involved in the towing of the floating structure to the desired location, it is contemplated that pivots 31 and 32 may be inclined to provide the desired spread of

legs

2 and 3 when in the down position and to allow

legs

2 and 3 to assume substantially parallel relationship to each other when in the up or towing position as is schematically shown in FIGURE 8 and hereinbefore de- 5 scribed. When such structure configuration is to be provided, then braces 3, 9, 10 and 11 will have to be eliminated and bolting

plates

37 and 39 will have to be sloped to enter

slots

38 and 40 during the movement of

legs

2 and 3.

With the legs positioned as shown in FIGURE 2, water ballast is added to the outer compartments of

legs

2, 3, 4 and 5 simultaneously from the compartments in platform 1 after unbolting the respective second bolting plates. The addition of water ballast to the leg compartments from the platform compartments will change the center of gravity of the legs outwardly while the center of mass through the buoyancy force acts is not changed. This shifting of the center of gravity outwardly will cause the legs to settle at their outer ends into the water and platform 1 will be raised upwardly from surface 98. If ballast is from a source other than platform 1, the structure as a whole will still displace sufficient water to remain floating in the water but will have more structure submerged than before ballast is added. The movement of the legs due to ballasting will continue until they reach the position illustrated in FIGURE 3.

Care should be taken and mechanical stops (not shown) provided if necessary to prevent the legs from being ballasted to a point, herein termed critical position, where the direction of righting moment is reversed. If any of the legs are allowed to reach such point then deballasting of the leg and ballasting of platform 1 might not allow the leg to be rotated into its upper position. By maintaining the angle of the legs with respect to the critical position below their respective pivots, proper return of the legs is assured solely by deballasting of the legs, by ballasting platform 1 and by both.

It should be noted that allowing the legs to assume the critical position below the pivot connections to platform 1 would result in instability of the structure and could result in a major accident during the deballasting of the legs since their upward movement could be restricted until they move away from their vertical position. If such movement is prevented until substantial deballasting has occurred then the forces due to buoyance of the legs would be tremendous as soon as the legs moved from the vertical position. At this point all of the legs are in the down position, and are locked in position by bolting through the bolting plates into the platform 1. It should be noted that platform 1 is substantially above water surface 98 and that the lower ends of the legs are still above floor 99. At this point the structure is said to have a reserve buoyancy, that is, additional ballast water must be added to position the legs of the structure on floor 99 as shown in FIGURE 4. This further ballasting is readily accomplished with the ballasting system.

Extreme care should be taken in the filling of the compartments in the legs with water ballast that platform 1 remains in a substantially horizontal position and that the legs are ballasted uniformly. This ballasting should be controlled from a central control (not shown) maintained on platform 1, and may be accomplished either manually by control of the pumps and valves or automatically by controls which are well known, to maintain the horizontal position of platform 1 during the ballasting of the legs.

Normally the device of the present invention will be designed to have legs of proper length and size so that the structure will have the desired reserve buoyancy for the depth of water in which the device is to 'be located. In the event that the water is relatively shallow in comparison to the length of the legs, then it is contemplated that the legs will be ballasted to a position less than the down position shown in FIGURES l, 3 and 4. The legs will then be locked in such position while the structure still has some reserve buoyancy, i.e., the legs are not touching the bottom 99. Such locking is accomplished by bolting through the respective bolting plates into platform 1. With the legs secured in such position, additional ballast is added and the whole structure will 7 lescend in the water until the legs rest firmly on bottom 9. It is further contemplated by the present invention hat the desired location may not have a bottom 99 which completely level, and therefore one or more of the legs nay be extended to different down positions to accomnodate such unevenness of bottom 99. Legs 4 and 5 vill 'be at the same position as long as sections 17 and [9 are joined, and

legs

2 and 3 will be at the same posiion unless

braces

8, 9, and 11 are omitted. If it s desired that legs 4 and 5 descend to different levels hen they should not be joined as shown in the drawing.

t is further contemplated by the present invention hat the location of the device may be in water having ufiicient depth that the legs will not set on the bottom, tl'ld therefore it is suggested that anchors having floats be )rovided to secure the structure in the desired location 11 a floating condition. Such anchor and float devices or fixing the desired location of a floating structure are vell known, and therefore are not illustrated in the lrawings.

When it is desired to relocate the structure of the :resent invention, the discharge and shifting of ballast s accomplished as hereinafter more fully explained. The lischar-ge of water ballast initially should return the .tructure to its condition of reserve buoyancy which is llustrated in FIGURE 3. At this point the bolting of he respective bolting plates into platform 1 should be lnbolted and then the discharge or shifting of water )allast continued until the structure is positioned in its owing position as illustrated in FIGURE 2. With the egs all in up position, they should be locked in place y bolting through their respective second bolting plates nto platform 1. The movement of the legs can easily )6 accomplished from one position to the other solely y the addition or discharge of Water ballast in the comartments contained in the tubular sections of the legs. t is contemplated, however, that in cases where sufiicient eserve buoyancy is not available because of the shallowless of the location, that additional mechanical means nay be provided for the rotation of the legs into their )referred down position whereby the desired reserve moyancy of the structure is maintained. Also, it may be lesirable to have such mechanical means for movement )f the legs to maintain their position during the periods :f bolting and un'bolting of their respective bolting plates 0 platform 1. Suitable winch, pulley and Wire ropes or )neumatic or hydraulic actuators are examples of the mechanical means contemplated by the present invention or assisting in the positioning of the legs. Such mechancal means should be capable of moving the legs without he assistance of ballasting and deballasting in the event if failure of the ballasting system.

The structure of the present invention will be contructed in different sizes, but because of the flexibility )f design and the variable positioning of the legs it is :ontemplated that, for example, a single structure will he built to accommodate water depths from 150 to 250 eet. This flexibility of the structure will allow a maxinum range of applicability for water depths for each ize structure.

Also in the design of a barge platform in accordance vith the present invention consideration must be given 0 the maximum wave height to which the structure will ie exposed when set on the ocean floor. Maximum wave ieights are normally assumed to be from 30 to 50 feet n normal offshore locations. Therefore, for any given lepth when the structure is to rest on the ocean floor, he minimum length of legs must be at least equal to the naximum depth of the water at the location plus the lesired height of the hinges above the waters surface )lllS an added length suificient to enable the legs to be n contact with the ocean floor without reaching a vertical iosition plus an added length of at least 30 to 50 feet 0 be equal to the expected maximum wave height.

The preferred form of the legs is tubular as shown,

however, the legs may be constructed from structural steel and be provided with reservoirs integral with each leg and the reservoirs must have sufficient buoyancy to support the legs, the platform and the payload and to lift the whole structure so that the platform is at least 30 feet above the surface of the water. Such reservoirs should also be provided with pump and controls for ballasting and de'ballastings as previously described herein relating to such pump and controls in the legs shown in the drawings.

The operation of the ballasting system is best understood in reference to FIGURE 7. With all compart ments empty the legs will be positioned as shown in FIGURES 2 and 5. Ballasting is commenced by opening valve 64 and supplying water to inlet 63. With valve 69 open, motor is started and pump 62 will pump water ballast through line 66, valve 69 and line 72 into compartment 57. It is suggested that if tubular section 12 is provided with a separate filling system that its pump be started at the same time as pump 62 and that compartment 50 be filled at the same time as compartment 57. If compartment 44 is to receive ballast, then it is suggested that it be filled first to provide the maximum turning moment on leg 2 to more quickly rotate leg 2 into its down position. As previously mentioned, the ballasting of all legs should proceed simultaneously and platform 1 should be maintained in a substantially horizontal position. When the compartments which are being filled first are completely full of water ballast, the next compartment to be filled should be the compartment which is the farthest horizontal distance from platform 1 and that compartment which will provide the maximum turning moment for the rotation of the leg. \/Vhen the leg has been partially ballasted by filling compartment 44, it is suggested that compartment 50 be filled before compartment 57 since it will have a greater effect on the movement of the leg into its down position. The order of filling of the compartments, assuming that they are all independently controlled, will proceed as follows: Compartment 44 should be filled first, then compartment 50, then compartment 57, then compartment 51, and, with the leg nearing its down position, compartment 52 should be filled to provide the final turning of the leg into its desired position.

Compartments

58 and 59 may be filled to overcome the reserve buoyancy after the legs have been locked in their desired position. It is suggested that when the structure is fixed in position on the bottom, that all compartments be completely filled to overcome any buoyancy and thereby provide a stable position for the structure which will not be affected by movement of the water, either by waves at the surface or by currents.

During the ballasting, when compartment 57 has been filled and it is desired to commence filling of compartment 58, valve 69 should be closed and valve 68 opened. The completing of the filling of compartment 57 may be determined by the observing of water being discharged through vent line 73, or the desired amount of water ballast may be metered, and, when sufiicient ballasting of compartment 57 has been accomplished, then the ballasting of the next compartment may be commenced by the changing of the

valves

67, 68 and 69.

Vent lines

73, 74, 75, 95, 96 and 97 are provided to all compartments which are to receive water ballast to prevent the building up of pressure within the compartments during filling and the creating of a vacuum in the compartments during discharge of water ballast. It is preferred that each compartment be filled less than completely full to prevent the filling of the vent lines. With the vent lines full, it is noted that the interior of the compartment would always be subject to a slightly higher pressure than the exterior of each compartment due to the slight height of the vent lines outlet above the level of the water. Filling of the vent lines will cause a pressure differential between a completely full compartment and its adjoining compartment if the adjoining compartment is not completely full. To avoid such pressure differentials and to always assure that the pressure in the compartments is lower than the water pressure surrounding the compartment, it is preferred that the vent lines not be filled and that the lower portions of the legs be desi ned to withstand the exterior pressure of the water at the depth to which they will be exposed.

The discharge of water ballast from the legs should be commenced by opening valve 86 and opening valve 81 by actuating control rod 83. With valve 81 and valve 85 open, motor 84 should be started and water will be pumped from compartment 60 through line 78, valve 81, manifold 81a, pump 82, line 85 and valve 86 to discharge normally into the compartments of platform 1 or in the body of water in which the structure is located. When compartment 64 is empty, valve 81 should be closed and valve 8% opened to proceed with the emptying of compartment 59. It should be noted that the compartments in tubular section 12 may be emptied of water ballast at the same time as the compartments in tubular section 13 are being emptied by the opening of

valve

90, 91 or 92, since both manifold 81a and manifold 93 are connected directly into the inlet of pump 82. Sufiicient ballast should be removed until the structure has returned to its position of reserve buoyancy illustrated in FIGURE 3, then the legs should be unbolted from platform 1, and thereafter the discharge of ballast should proceed until all of the legs have returned to their towing position. Care should be taken in the discharge of ballast to assure that platform 1 remains substantially level. This may be done through a manual control or by automatic control as hereinbefore suggested with relation to adding ballast to the legs.

From the foregoing it can be seen that the present invention provides a platform for offshore locations which will float for towing to location and Which will position itself for drilling or other application by the ballasting of compartments in its legs. The ballasting of the legs and de-ballasting of the platform will cause the legs of the device to rotate from a substantially horizontal or floating position into a downwardly and outwardly extending position, and further ballasting after locking the legs in position will set the device on the bottom in the desired location. The present invention provides a floatable platform for marine operations such as drilling having downwardly and outwardly extending legs engaging the floor of the body of water in which the device is to be located wherein the leg positions provide great flexibility of positioning and stability for the platform which they support.

The present invention provides a floatable barge platform hingedly connected to buoyant legs which are forced down whereby the platform in raised above the waters surface. \Vhen the legs are forced down to the proper position they are set so as to prevent them from turning any more around the hinges and the whole system may then be brought to rest on the oceans floor by ballasting.

The invention further provides a barge platform structure capable of being ballasted to any desired position and deballasted to return to its unballasted position. Thus, the position of the structure is controlled by the amount of ballast and by controlling the ballast stability of position is maintained. Also, this invention provides a floatable barge platform having a plurality of legs at least two of which pivot from a substantially parallel towing position to a divergent submerged position.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the method, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. A platform structure for offshore location comprisa platform, I

a plurality of V-shaped legs,

each leg including two tubular sections jointed together at one end and secured together at its other end by an arm to form the V-shaped legs,

each of said legs being pivotally secured to said platform at the arm end of one of said tubular sections,

each of said tubular sections being compartmented to receive ballast,

a bolting plate secured to the arm end of the tubular section of each leg opposite the tubular section which is pivotally secured to said platform for securing said leg to said platform, and

means for ballasting and deballasting the compartments in said tubular sections to pivot said legs with respect to said platform.

2. A platform structure according to claim 1 wherein each of said legs includes a reserve buoyancy to lift said platform when said legs have been pivoted by ballasting into a supporting relation below said platform.

3. In a method of operating a floating platform barge having a plurality of buoyant legs, said buoyant legs being characterized by having a length greater than the depth of the water in which the floating platform barge is to be used, each leg being pivotally secured to said platform, starting with the legs extending substantially horizontally with respect to said platform, the steps of ballasting said legs to move said legs downward in the water to a position extending downwardly and outwardly from said platform,

the downward movement of said legs in the water responsive to said ballasting lifting said platform above the water, and

locking said legs to said platform.

4. In the method as set forth in claim 3, the additional step of stopping the pivoting movement of said legs with respect to said platform before said legs reach a substantially vertical position below their respective pivotal connections to said platform.

5. In the method as set forth in claim 3 wherein said ballasting of the legs includes the step of shifting ballast from said platform to the outer ends of said legs to reduce the weight of said platform.

6. In the method as set forth in claim 3 wherein the downward movement of said legs in the water responsive to said ballasting and the combined reserve buoyancy of said legs when pivoted to a final supporting position lifts said platform above the water.

7. In a method of operating a floating platform barge having a plurality of buoyant legs, said buoyant legs being characterized by having a length greater than the depth of the water in which the floating platform barge is to be used, each leg being pivotally secured to said platform, starting with the legs releasably locked to the platform and extending downwardly and outwardly below the platform and supporting the platform above the water, the steps of releasing the locked connection between the legs and the platform, and

deballasting the legs to pivotally move the legs upward in the water to a substantially horizontal position,

the movement of the legs upwardly in the water responsive to said deballasting progressively decreasing the support of the platform by the legs to lower the platform to the surface of the water.

8. A floatable structure for offshore location, com

prising a platform,

a plurality of legs, each leg being pivotally secured at one end to said platform and adapted to pivot with respect to said platform,

means for admitting ballast to said legs,

means controlling the admission of ballast to said legs whereby said legs are pivoted from a substantially horizontal position downward in water below said platform, said legs having sufficient reserve buoyancy when ballasted to a position below said platform to lift said platform above the surface of the water, and

releasable locking means securing said legs to said platform to prevent pivoting of said legs with respect to said platform.

9. A floatable structure for offshore location, comprising a platform,

a plurality of legs, each leg being pivotally secured at one end to said platform,

means for admitting and discharging ballast to and from said legs, and

means controlling the ballasting of said legs whereby said legs are pivoted downward from a substantially horizontal towing position to a position below 'said platform,

at least two of said legs having inclined planes of rotation, said planes of rotation being inclined with respect to a vertical plane and extending outwardly and downwardly below the platform with respect to said vertical plane whereby said two legs are substantially parallel in their substantially horizontal towing position and diverge with respect to each other in all other positions.

10. A floatable structure for offshore location, comprising a platform,

means for shifting ballast between said legs and said platform, and means controlling the shifting of ballast between said legs and said platform whereby said legs are adapted to be pivoted with respect with said platform between a substantially horizontal position and a position wherein said legs extend downwardly and outward below said platform, said legs having sufficient reserve buoyancy to lift said platform when said legs are pivoted by ballasting to a position below said platform.

11. A structure according to claim 8 wherein the pressure exerted by the ballast in each leg is less than the water pressure on exterior of each leg and said legs have sufficient structural strength to withstand the pressure differential caused thereby.

12. A structure according to claim 10 wherein the combined reserve buoyancy of said legs is sufficient to lift said platform at least thirty feet above the surface of the water when said legs are positioned below said platform.

13. A fioatable structure according to claim 10 wherein said platform includes a plurality of ballast compartments,

each of said legs includes a plurality of ballast compartments, and

said controlling means controls the shifting of ballast between the ballast compartments of said platform and the ballast compartments of said legs.

14. A platform structure for offshore location, comprising a platform,

a plurality of legs,

each leg composed of two tubular sections joined together at one end and secured together at its other end by an arm to form a V-shaped leg,

means pivotally securing each of said legs to said platform at the arm end of one of the tubular sections of said legs,

each of said legs being compartmented to receive ballast,

means for ballasting and deballasting the compartments in said legs, and

means releasably securing the arm ends of the other tubular section of said legs to said platform in at least two positions to prevent pivoting movement of said legs with respect to said platform.

15. A platform structure for offshore location, comprising a platform,

a plurality of legs,

each leg having two tubular sections joined together at one end and secured together at their other end by an arm,

each of the legs being compartmented to receive ballast,

means for ballasting and deballasting the compartments in said legs,

said tubular sections being spaced apart at their arm ends a greater distance than at said joined end whereby said legs provide a positive GM at all positions of the legs with respect to said platform, and

means releasably securing the arm end of the other tubular section of said legs to said platform in at least two positions to prevent pivoting movement of said legs with respect to said platform.

References Cited by the Examiner UNITED STATES PATENTS 2,598,329 5/1952 Wilson 61 46.5 2,600,761 6/1952 Halliburton 6146.5 2,608,829 9/1952 Knapp 6146.5 2,622,404 12/1952 Rice 61-46.5 2,968,930 1/1961 Mangone 6146.5

CHARLES E. OCONNELL, Primary Examiner.

JACOB SHAPIRO, Examiner.

Claims

1. A PLATFORM STRUCTURE FOR OFFSHORE LOCATION COMPRISING, A PLATFORM, A PLURALITY OF V-SHAPED LEGS, EACH LEG INCLUDING TWO TUBULAR SECTIONS JOINTED TOGETHER AT ONE END AND SECURED TOGETHER AT ITS OTHER END BY AN ARM TO FORM THE V-SHAPED LEGS, EACH OF SAID LEGS BEING PIVOTALLY SECURED TO SAID PLATFORM AT THE ARM END OF ONE OF SAID TUBULAR SECTIONS, EACH OF SAID TUBULAR SECTIONS BEING COMPARTMENTED TO RECEIVE BALLAST, A BOLTING PLATE SECURED TO THE ARM END OF THE TUBULAR SECTION OF EACH LEG OPPOSITE THE TUBULAR SECTION WHICH IS PIVOTALLY SECURED TO SAID PLATFORM FOR SECURING SAID LEG TO SAID PLATFORM, AND MEANS FOR BALLASTING AND DEBALLASTING THE COMPARTMENTS IN SAID TUBULAR SECTIONS TO PIVOT SAID LEGS WITH RESPECT TO SAID PLATFORM.