US3347052A

US3347052A - Method of and apparatus for transporting, erecting, and salvaging off-shore structures

Info

Publication number: US3347052A
Application number: US450976A
Authority: US
Inventors: James L Steitle; Robert H Macy; Maurice B Thomas
Original assignee: MOVIBLE OFFSHORE Inc
Current assignee: MOVIBLE OFFSHORE Inc
Priority date: 1965-04-26
Filing date: 1965-04-26
Publication date: 1967-10-17
Anticipated expiration: 1984-10-17

Description

Oct. 17, 1967 J. 1.. STEITLE ET AL 3,347,052

METHOD OF AND APPARATUS FOR TRANSPORTING, ERECTING, AND

SALVAGING OFF- SHORE STRUCTURES Filed April 26, 1965 3 Sheets-Sheet l Jamar 1. J2@/?/@ Robe/*2 b". Mary May/v66 5. 7770/7705 1NVENTOR3 I, M BY J a #4 aha/I ATTO/P/VE'V6 Oct. 17, 1967 METHOD OF AND APPARATUS FOR TRANSPORTING, ERECTIN SALVAGING OFF-SHORE STRUCTURES Filed April 26, 1965 J. L. STEITLE ET AL G, AND

3 Sheets-Sheet 2 James Z. Jze/f/e fiaberz H. Macy Mao/v09 5. Thomas INVENTORS Oct. 17, 1967 J s T ET AL 3,347,052

METHOD OF AND APPARATUS FOR TRANSPORTING, ERECTING, AND SALVAGING OFF-SHORE STRUCTURES Filed April 26, 1965 3 Sheets-Sheet 5 United States Patent Ofifice 3,347,52 Patented Oct. 17, 19%? 3,347,052 METHOD 6F AND APPARATUS FOR TRANSPORT- lNG, ERECTKNG, AND SALVAGING OFF-SHGRE STRUCTURES James L. Steitle, Lafayette, La, and Robert H. Macy, Pascagonla, Miss and Maurice B. Thomas, Houston, Tex., assignors to Movible ()tishore, Inc., Houston, TeX., a corporation of Delaware Filed Apr. 26, 1965, Ser. No. 450,976 4 Claims. (Cl. 6146.5)

ABSTRACT OF THE DISCLGSURE The present invention i directed to a method of and apparatus for transporting, erecting and salvaging offshore structures, and more particularly, is directed to a method and apparatus of transporting, erecting and salvaging an offshore drilling rig by means of pontoons. The present invention utilizes releasably attached pontoons at the top of the rig on two opposing sides and on the bottom of the rig on one of said sides. This arrangement enables one to tow the rig to the site in a horizontal position, and to easily and quickly rotate it into a vertical position, and lower it onto the ocean floor. The pontoons may then be released and later re-attached for salvage purposes.

Generally, there is an increasing use of oflshore drilling rigs for drilling oil and gas wells on the floor of a body of water. However, these rigs or jackets are extremely bulky and large. For instance, a jacket for use in 200 feet of Water may have a length of 220 feet and a weight of 740,000 pounds. The method of transporting, erecting, and salvaging these rigs by means of barges and cranes is expensive and dangerous because of the size of the drilling rigs.

It is a general object of the present invention to provide a method of and apparatus for transporting, erecting, and salvaging, if desired, a drilling rig or jacket without the use of barges or dern'cks.

A still further object of the present invention is the provision of a method of and means for transporting, erecting, and salvaging drilling rigs or jackets by means of pontoons to provide the necessary stability and buoyancy.

Still a further object of the present invention is the provision of a method of and means for transporting, erecting, and salvaging, if desired, a drilling rig with a minimum of pontoons and yet providing a high degree of reliability, safety and control.

A still further object of the present invention is the provision of a method of and means for transporting, and erecting drilling rigs on the floor of a body of water by utilizing pontoons to horizontally float the rig in a generally horizontal position out of the water for providing greater safety and less towing resistance so that the rig may be towed to the desired location, and thereafter by the actuation of suitable ballasting controls the pontoons will rotate the rig to a generally vertical floating position and set it on the floor of the water. Thereafter, after use, the rig can again be salvaged by filling the pontoons with air to raise the rig and rotate it to a generally horizontal position for transportation to a new location.

Still a further object of the present invention is the provision of a method of and apparatus for transporting,

erecting, and salvaging, if desired, an offshore drilling structure with a minimum of pontoons which provide the necessary stability and buoyancy for horizontally supporting the rig for transportation to location, and which are suitably positioned and located on the rig to rotate the rig from a horizontal to a vertical position and then set the rig on the floor of the water wherein the pontoons may be readily removed if desired to reduce the wave forces on the structure. And after the use of the rig is completed, the pontoons may be reconnected to the rig for removing the rig from the water floor, and rotating it to a horizontal position for transportation to a new location.

Yet a still further object of the present invention is the provision of a method of and apparatus for transporting, erecting, and salvaging an oflsho-re. drilling rig having at least four legs and having a top and bottom by providing a first elongate pontoon releasably connected to the outside of one of the legs adjacent the bottom of the rig and a second elongate pontoon releasably connected to the outside of a second leg adjacent the bottom whereby the first and second pontoons will support the bottom of the rig out of the water when the rig is being transported horizontally on the water, and a third and fourth pontoon are provided releasably connected to the outside of the first and second legs, respectively, at the top of the rig whereby the third and fourth pontoons will support the top end of the rig out of the water when the rig is being transported horizontally in the water, and fifth and sixth elongate pontoons are releasably connected to the outside of the third and fourth legs, respectively, at the top of the rig, and suitable selective ballasting means is connected to each of the pontoons for selectively controlling the ballast of each of the pontoons whereby the rig may be suitably rotated from the horizontal to the vertical position and lowered in the water and can again, after use, be lifted and rotated to a horizontal position for movement to a new location.

Yet a still further object of the present invention is the provision of a method of and apparatus for transporting and erecting a four leg offshore drilling rig by providing floating pontoon means on one side of the rig at both the top and the bottom for floating the rig to location in a generally horizontal position, providing floating pontoon means on the side opposite the one side of the rig at the top, ballasting the floating pontoon means at the bottom of the rig while all of the top floating pontoon means are buoyant whereby the rig will assume a vertical floating position supported by the top floating pontoon means, and ballasting all of the floating pontoons at the top of the rig thereby vertically submerging the rig in a vertical position in the water. And the method further comprehends salvaging and transporting the rig to a new location by filling the floatable pontoons connected to the top of the rig on the side opposite from the side on which the lower floatable pontoons are connected with air thereby causing the rig and the lower floatable pontoons to rotate about the air filled pontoons until the lower pontoons pass beyond a vertical plane through the air filled pontoons, filling the lower pontoons with air thereby rotating and floating the bottom end of the rig out of the water, and filling the pontoons at the top of the rig on the same side as the lower pontoons with air thereby horizontally floating the rig out of the water for transporting the rig to a different location.

Still a further object of the present invention is the provision of a method of and apparatus for transporting, setting, and salvaging a four legged off-shore drilling structure with a minimum of pontoons by providing first pontoon means connected to the outside of the rig on one side thereof and at one end for supporting the one end out of the water, providing the second pontoon means connected to the rig and positioned outside the rig on the one side and at the second end thereof for supporting the second end out of the water, providing third pontoon means connected to the rig and positioned outside of the rig on the side opposite the one side and at the second end thereof, and in which the second pontoon means each include water outlets at each end adjacent the side remote from the connected rig for emptying the second pontoon means as the rig is rotated in either direction.

A stillfurther object of the present invention is the provision of a method of and apparatus for transporting, setting, and salvaging an off-shore drilling rig by the use of pontoons all of which may be releasably connected to and disconnected to the rig by suitable means extending above the water surface.

Other and further objects, features and advantages will be apparent from the following description of a presently preferred embodiment of the apparatus of the present invention, taken in conjunction with the accompanying drawings, where like character references designate like parts throughout the several views, and where FIGURE 1 is a schematic side elevation illustrating the method and apparatus of the present invention wherein a minimum number of pontoons are utilized to horizontally support and control the erection of a drilling rig,

FIGURE 2 is a side elevation illustrating the drilling rig of FIGURE 1 being rotated from a horizontal position by the pontoons,

FIGURE 3 is a side elevation of the apparatus of FIG- URE 1 illustrating the rig rotated to and floating in a vertical position,

FIGURE 4 is a side elevation of the apparatus of FIG- URE. 1 illustrating the drilling rig in a vertical position on the bottom of a body of water,

FIGURE 5 is a side elevation of the present apparatus illustrating a rig being rotated from a floating vertical position for raising the rig,

FIGURE 6 is a side elevational view showing the rig in an intermediate position of being rotated from the vertical floating position to the horizontal position,

FIGURE 7 is an illustration of one type of ballasting connections for filling and emptying the pontoons with water and air,

FIGURE 8 is a cross-sectional view taken along the line 8-8 of FIGURE 1, and

FIGURE 9 is a cross-sectional view taken along the line 99 of FIGURE 8.

Referring now to the drawings, and particularly to FIGURES l and 8, an off-shore drilling rig is shown generally indicated by the reference numeral 10, which is desired to be moved to a location and placed in a vertical position on the floor of the body of water for conventional drilling operations. The present invention is generally directed to providing a minimum number of pontoons specifically positioned and whose buoyancy is so controlled to perform the necessary operations of transporting, erecting and salvaging the conventional four-leg drilling rig 10.

In order to avoid the use of an expensive barge for transporting .the rig 10 to location, suitable pontoon means are connected to one side of the rig 10 at each end for supporting the rig 10 in a generally horizontal position. Thus,

pontoons

12 and 14 are connected to one side at the top of the rig, and similar pontoons 16 and 18 (not shown) are connected to the same side of the rig, but at the bottom end of the rig 10. It is to be noted that the pontoons are preferably releasably connected to the

lowerlegs

20 and 22 outside of the rig in position to buoyantly hold the rig 10 out of the Water in a horizontal position to reduce towing resistance. In

addition, it is noted from FIGURE 8 that the pontoons on the rig 10 extend outwardly from each side of the

legs

20 and 22 so that the rig is stable when it is floated horizontally thereby reducing the tendency for the rig 10 to capsize. After the

pontoons

12, 14, 16 and 18 are connected to and support the rig 10 out of the water, the rig may be suitably towed to the desired location.

Pontoons

24 and 26 are suitably connected to the top of legs 28 and 30 whereby pontoons 24.and 26 are on the opposite side of the rig 10 from the pontoons 16 and 18 which are positioned at thelower end of the rig. Pontoons 24 and 26 act in conjunction with the other four

pontoons

12, 14, 16 and 18 for suitably rotating the rig 10 from a horizontal to a vertical position and back. Thus, when the rig 19 reaches the desired location the lower pontoons 16 and 18 are filled with water from a suitable ballasting system, not shown, and the rig thereby rotates from the horizontal to the vertical position as shown in FIGURE 3, or may, as shown in FIGURE 2, make an angle of about 10 from the vertical and floats above the bottom 32 by virtue of the buoyancy of the upper tanks '12, 14, 24 and 26 which are still filled with air. As has been stated, generally, the rig 10 will assume a generally vertical position in the water supported by the upper tanks. The rig 10 may then be lowered onto the bottom 32,.as best seen in FIGURE 4, by suitably filling all of the

upper tanks

12, 14, 24 and 26 with water. Of course, assuming that the rig 10 makes a slight angle from the vertical as shown in FIGURE 2,

pontoons

24 and 26 would be supplied with enough water to make the unit 10 stand exactly vertical, as shown in FIGURE 3, before filling the remaining two

upper pontoons

12 and 14 with water.

While, of course, the pontoons can be secured to the rig 10 such as by welding, to form a permanent installation, it is usually desirable to remove the pontoons once the rig 10 is in place and later reinstall them for the purpose of recovering the rig, if desired. Since the pontoons may be relatively large, for example, in a 220 foot rig the pontoons may be 42 feet in length and 17 feet in diameter, the removal of the pontoons from the rig would reduce the wave forces on the rig structure 10.

and would also make the pontoons available for use on other rigs.

Referring now to FIGURES 8 and 9, any suitable means for releasably connecting the pontoons to the rig 10 may be used. For example, a suitable clamp 40 may be pivotally secured to the pontoon by a hinge member 42 whereby the member 40 may be rotated to encircle and engage a leg so that the pontoon will securely engage the leg by means of plurality of clamps 40" and seating pads 44. The clamps may be rotated into gripping engagement with a leg by means of a suitable rod 46 connected to the clamp 40 which extends to the top of the rig 10 for actuation. Thus, the pontoons may be releasably connected and disconnected by actuation from the surface thereby avoiding the use of underwater divers. For providing additional stability, as best seen from FIGURE 8, suitable bracings 48 may be provided between adjacent pairs of pontoons for additional stability. Of course, the lower pontoons 16 and 18 may be similarly attached, but the hinges 40 should preferably be on the opposite side of the legs so that the actuating rod 46 will be offset from the hinges 40 and actuating rods on the upper pontoons.

When it is desired to salvage and remove the jacket or rig 10, the water in the

upper pontoons

12,14, 24 and 26 is replaced with air if the jacket is stuck in the soil or mud on the bottom 32. These four upper pontoons will provide the necessary vertical pull to break the rig 10 out of the mud so that the rig will assume a vertical floating position as best seen in FIGURE 3. However, assuming the jacket has been broken out of the mud or is sitting free on the bottom 32 the correct removal sequence, is to fill

upper tanks

24 and 26 with air while the opposite :two

upper tanks

12 and 14 and the lower two tanks 16 and 18 remain ballasted with water. As best seen in FIGURE 5, this causes the rig to rotate about the upper

buoyant tanks

24 and 26 until the center of the lower tanks 16 and 18 pass beyond the center of the

upper tanks

24 and 26. When this occurs the lower tanks 16 and 18 may then be filled with air and the rig 10 then assumes the position shown in FIGURE 6 with the bottom end higher than the top end, but with the rig in a stable position.

Tanks

12 and 14 are then filled with air to raise the upper end of the rig 10 whereby the entire rig is again in a floating horizontal position, as in FIG- URE l, and is in a transit condition on the water surface for going to a new location. It is to be noted that the combination of the location of the tanks and their sequence of operating assures that the rig 10' can be salvaged without the use of a crane and without danger of capsizing.

Referring now to FIGURE 7, a typical pontoon 24 is shown having an air inlet and outlet 50 and a water inlet and outlet 52. It is to be noted that the water inlet is an elongate tube with its inside end extending to the bottom and far end 58 of the pontoon 24. This arrangement of the air and water inlets and outlets will adequately provide for emptying and filling

pontoons

24, 26, 16 and 18. However, for

pontoons

12 and 14, since they may be tilted in either direction in an entire erecting and salvaging sequence of operation, it is necessary to provide an additional water outlet 56 at the bottom and at the other end 60 to expel water from the pontoon when the end 60 is lower than the end 58.

The present invention thus provided a limited number of pontoons which are positioned at specific locations and which can perform the functions of supporting the rig 10 while it is in a generally horizontal position for towing to a location, can be selective actuation of the buoyancies of the various pontoons move the rig to a vertical position and lower it to the water floor, and when it is desired to remove the rig, the pontoons can then again be floated in a controlled sequence to raise up the rig, rotate it to a horizontal position and buoyantly support it for towing to a new location.

It is believed that the method of the invention is apparent from the foregoing description of the apparatus of the invention. The method, however, comprehends the steps of transporting and erecting an ofl-shore drilling rig, having at least four legs by providing floating pontoons on one side of the rig at both the top and bottom for floating the rig to location in a generally horizontal position, providing floating pontoons on the side opposite the one side of the rig at the top, ballasting the floating pontoons at the bottom of the rig while all of the top floating pontoons are bouyant whereby the rig will assume a vertical floating position supported by the top floating pontoons, ballasting all of the floating pontoons at the top of the rig thereby vertically supporting the rig in a vertical position on the water floor, and disconnecting all of the floating supports. The method further comprehends salvaging and transporting a four leg elf-shore drilling rig vertically positioned on the floor and extending into the water by connecting floatable pontoons to each leg at the top of the rig and extending below the water level, connecting ballasted floatable pontoons to the legs adjacent the bottom of the rig, filling the floatable pontoons connected to the top of the rig on the side opposite from the side on which the lower pontoons are connected with air thereby causing the rig and the lower floatable pontoons to rotate about the air filled pontoons until the lower pontoons pass beyond a vertical plane through said air filled pontoons, filling the lower pontoons with air thereby rotating and floating the bottom end out of the water, and filling the pontoons at the top of the rig on the same side as the lower pontoons with air thereby horizontally floating the rig out of the water for transporting to a different location.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned as well as others inherent therein. While a presently preferred embodiment of the invention is given for the purpose of disclosure, numerous changes in the details of construction, arrangement of parts, and steps of the process can be made which will readily suggest themselves to those skilled in the art and which are encompassed within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. A method of salvaging and transporting a four leg off-shore drilling rig vertically positioned on the floor and extending out of the water comprising,

connecting floatable ballasted pontoons to each leg at the top of the rig and extending below the water level, connecting ballasted floatable pontoons to two of the legs adjacent the bottom of the rig.

filling the floatable pontoons connected to the top of the rig on the side opposite from the side on which the lower floatable pontoons are connected with air thereby causing the rig and the lower pontoons to rotate about the air filled pontoons until the lower pontoons pass beyond a vertical plane through said air filled pontoons,

filling the lower pontoons with air thereby rotating and floating the bottom end of the rig out of the water, and

filling the pontoons at the top of the rig on the same side as the lower pontoons with air thereby horizontally floating the rig out of the water for transporting to a dilferent location. 2. A method of transporting, erecting and salvaging a four leg off-shore drilling rig comprising,

providing a floating pontoon on each end and outside of two adjacent legs for floating the rig to location in a generally horizontal position out of the water,

providing a floating pontoon on the two adjacent legs opposite said first two adjacent legs at the top of the ballasting the floating pontoons at the bottom of the rig while the pontoons at the top of the rig are buoyant whereby the rig will assume a vertical floating position with the bottom downward,

ballasting all of the floating pontoons at the top of the rig thereby vertically submerging said rig in a vertical position in said water whereby the rig is ready for use, and after use, salvaging said rig including,

filling the pontoons connected to the top of the rig on the side opposite from the side on which the lower pontoons are connected with air thereby causing the rig and the lower pontoons to rotate about the air filled upper pontoons until the lower pontoons pass beyond a vertical plane through said air filled upper pontoons, filling the lower pontoons with air thereby rotating and floating the bottom end of the rig, and filling the pontoons at the top of the rig on the same side as the lower pontoons with air thereby horizontally floating the rig out of the water for transporting it to a diflerent location. 3. An apparatus for transporting, erecting and salvaging an oitshore drilling rig having at least four legs and having a top and a bottom comprising,

first pontoon means releasably connected to the outside of said rig on one side at the bottom thereof for buoyantly supporting the bottom out of the water,

second pontoon means releasably connected to the outside of said rig on said one side and at the top of the rig for buoyantly supporting the top of the rig out of the water,

third pontoon means releasably connected to the outside of said rig on the side opposite said one side and at the top thereof,

ballasting means connected to each of said pontoon means for selectively regulating the ballast of each of said pontoons for transporting, erecting and salvaging said rig,

said second pontoon means having top and bottom surfaces essentially parallel to the top and bottom of said rig, and

a. Water outlet in each of said top and bottom surfaces for emptying said second pontoon means of water Whether tilted to either end.

4. The invention of claim 3 and including,

disconnecting means extending from said first pontoon 10 means toward the top of sald rig a distance sufficient to be above the Water level when the rig is erected for releasing said first pontoon means from said rig.

References Cited 1 UNITED STATES PATENTS Manes 61-46.5 Reeve 6146.5 Brinkmann 61-46.5 Sims 6182 Alcorn et a1. 6146.5 Borrmann 61--46.5 Clark 61-465 DAVID J. WILLIAMOWSKY, Primary Examiner.

JACOB SHAPIRO, Examiner.

Claims

1. A METHOD OF SALVAGING AND TRANSPORTING A FOUR LEG OFF-SHORE DRILLING RIG VERTICALLY POSITIONED ON THE FLOOR AND EXTENDING OUT OF THE WATER COMPRISING, CONNECTING FLOATABLE BALLASTED PONTOONS TO EACH LEG AT THE TOP OF THE RIG AND EXTENDING BELOW THE WATER LEVEL, CONNECTING BALLASTED FLOATABLE PONTOONS TO TWO OF THE LEGS ADJACENT THE BOTTOM OF THE RIG. FILLING THE FLOATABLE PONTOONS CONENCTED TO THE TOP OF THE RIG ON THE SIDE OPPOSITE FROM THE SIDE ON WHICH THE LOWER FLOATABLE PONTOONS ARE CONNECTED WITH AIR THEREBY CAUSING THE RIG AND THE LOWER PONTOONS TO ROTATE ABOUT THE AIR FILLED PONTOONS UNTIL THE LOWER PONTOONS PASS BEYOND A VERTICAL PLANE THROUGH SAID AIR FILLER PONTOONS, FILLING THE LOWER PONTOONS WITH AIR THEREBY ROTATING AND FLOATING THE BOTTOM END OF THE RING OUT OF THE WATER, AND FILLING THE PONTOONS AT THE TOP OF THE RIG ON THE SAME SIDE AS THE LOWER PONTOONS WITH AIR THEREBY HORIZONTALLY FLOATING THE RIG OUT OF THE WATER FOR TRANSPORTING TO A DIFFERENT LOCATION.