US2631742A - Marine edifice - Google Patents

Description

March 17, 1953 R. WHITE MARINE EDIFICE 2 SHEETS-SHEET 1 Filed Aug. 4. 1947 I i a IE. R

a E ww INVENTOR:

. Ross WHIT W3 mm A T TORNEY March 17, 1953 R. WHITE MARINE EDIFICE 2 SHEETS-SHEET 2 Filed Aug. 4. 1947 INVE-NTOR: Ross WHITE BY 2 Z 2 ATTORNEY Patented Mar. 17, 1953 MARINE EDIFICE Ross White, Houston, Tex., assignor to Brown and Root, Inc., Houston, Tom, a corporation of Texas Application August l, 1947, Serial-No. 765,857

1 Claim. 1

This invention pertainsto a marine; edifice suitable for a base of operations, particularly .marine construction operations such as offshore drilling for petroleum'.

Thejprincipal' object of the invention is to make it possible.- to carry onsuch operations during all types of weather excepting hurricanes and storms of likeseverity.

It is, a further object of the invention to minimizethe dangers to life and property of such operations.

A still further object of the invention is to reduce the costof such operations.

Briefly described, the invention contemplates the provision of a. small stationary platform supported .outof the water on piling, from which platform operations such as drilling .an under water well hole. may be. carried on. At a considerable distance from the. platform a tower is erectedv out of the Water and betweenthis tower and, .a. similar tower mounted on or near the main platform there will be mounted a highline on which an ordinary cable. car can be suspended and operated to move back and forth between the towers and up and down beneath the highline. Between the main platform and the tail tower for the highline a large floating vessel is moored. Preferably, the vesselis moored with its bow in the direction ofv the prevailing wind, the mooring being adjustable from the vessel to take care of minor shifts in the wind so that the vessel can always be made to face directly into the wind. The vessel should be ofsuch length that itwil-l span the distancebetween Wave crests of any ordinary waves which areencountered in the area where the construction is to be carried on. By the term ordinary waves is meant such waves'as occur during ordinary weather, rough as Well as calm, but excluding hurricanes and storms of like severity." Usually such waves will not be overtwo hundredfeet long.

On board the floating vessel are carried all the necessary supplies and personnel needed for carrying on the marine construction. Bothtmen and materials are transferred to the working platform asneeded by. means of the cable car. Certain fluid materials such aswater, fuel oil and drilling: mud: may be transferred from the'fioating vessel to the main: platform by means of underwater pipes connected to the vessel by flexible users.

The advantages ofjthe-invention as just de scribed can most easilybe pointed out by comparisonwith anotherproposed form of operating base for offshore drilling comprising a fixed plat.- form; which large enough to carry not only 2 the dri11ing rig but also a substantial quantity of'materials and equipment such as pipe and mud and also to provide a permanent living quarters for the workmen. Such an arrangement has a high initial cost and a low salvage value when the drilling operation is completed. In addition there is a great risk of loss or serious damage to the platform and the equipment thereon-during conditions of bad weather, for the entire platform being immobile is exposed: to the full force of the wind and sea at all times. Offshore drilling conducted on even the largest fixed platform which can be economically constructed is not a self-sufficient operation and the platform must be continually supplied with pipe, drilling mud, fuel oil, and provisions from shore'by small boats or barges. Thissupply may be interrupted during rough weather which makes it dangerous to personnel and equipment for small barges to go alongside the platform for unloading; A third disadvantage of the fixed platform system is the personnel problem. Not only are the personnel exposed to danger by being unable toleave the site of drilling operations in case'of severe storm or hurricane but their quarters for living are necessarily cramped. There is the-further problem of making suitable disposition of off-shift personnel in a manner so as-not to affectthe efiiciency nor morale of the men who-are working.

All three disadvantages of the large fixed platform system of offshore drilling are overcome by the present invention; thus since only a small platform is provided of just sumcient size to accommodate the derrick, draw works and high pressurepumps, together with a small supply of equipment and. materials, it will not have. nearly the high initial'cost of a large platform nor will there be as great a problem of salvagingv the platform when the drilling operation has been completed and it is desired to move the platform elsewhere; Since the structure need not carry such a heavy weight of supplies a minimumof lateral bracing can be used so as to'reduce the area exposed to violent wave action. Only a single deck'need beprovided, which can be arranged in -pan'els for rapid erection and dismantling. All large stores ofequipm'ent and'all-housing and'messing facilities and personnel willbe provided'on' the floating vessel which may easily be. moved from one location to another when drilling operations have been completed. In-case of. severe stormxorv hurricane the vessel canbe removed to a safe position; Such supplies and material as are neede'don the platform caneasily be transferred from the floating vessel to: the

platform by means of the cable car. This can be accomplished even in rough weather since a large vessel will have but a small rise and fall due to the fact that it bridges between waves rather than rides on an individual wave.

For a detailed description of a preferred embodiment of the invention reference will be had to the accompanying drawings in which- Figure 1 is an elevation of a marine edifice according to the invention, and

Figure 2 is a plan view thereof.

Referring to Figure 1 there is shown a platform l supported on piling II. The piling is driven or otherwise placed into the ground beneath the floor l2 of the body of water [3. Light cross braces such as that indicated at l4 may be used to tie the piles together. Where the platform IQ is to be used as a base from which to carry on drilling operations a derrick [5 may be erected on the platform [0. At one side of the platform In there is erected a tower I6.

At a considerable distance from the platform l0, perhaps 500 feet more or less, a second tower I! is erected on piles l8 which, like the piles H, are placed into the ground beneath the floor of the body of water l3. In some cases where drilling operations are to be carried on fairly near to the shoreline the tower I! may be erected on dry land but in the usual case both towers will be over water.

Between the towers l6 and I! there is placed a cable way of known construction which may comprise, for example, a main supporting cable fixed each end to opposite towers. A carriage 2! is supported on wheels which run on the cable 20. The carriage 21 can be moved back and forth along the cable between the towers l6 and I! by means of a traversing cable 22 which passes around sheaves at the tops of the towers I6 and I1 and the ends of which are both connected to the carriage 2|. A bight of the cable at tower 16 passes around reversible winch 23. A skip 24 is supported on a hook depending from sheave 25 which in turn is supported from the carriage 2| by a hoist line 26 fixed at one end to the carriage 2i and passing around the sheave 25 and a pulley on the carriage 2|. The other end of the hoist line 26 passes through guides 2i suspended from the main cable 20 and thence over a sheave at the top of tower l'l down to another reversible winch 28.

Beneath the cable way there is moored a floating vessel 30. Between the vessel 30 and the platform l0 there are suitable conduits for fluid materials, each of which includes a flexible hose 3| connected to an underwater pipe 32 laid on the floor 12 and a riser 33. These fluid conduits are shown in plan view in Figure 2 where by way of example there are shown three conduits 34, 35 and 36 for carrying low pressure mud, fuel oil, and water from the vessel 30 to the platform I0 where drilling operations are carried on.

Figure 2 illustrates a preferred method of mooring the vessel 30. The vessel is connected by 4 cables 4|, 42, 43 and 44 to spring buoys 45, 45, 41 and 48. The spring buoys comprise merely large buoys connected by very heavy chains 49, 50, 5| and 52 to heavy anchors such as that shown at 53 which preferably is of the type known as the Eell anchor which has two long angularly disposed tapered flukes extending backward from the anchor stem. The buoys 45, 46, 41 and 48, being of large size will normally remain out of water and the heavy chains connecting them to the Bell anchors will assume the form of a catenary. In case of a sudden force applied to the vessel by wind or wave the spring buoys will act as shock absorbers, reducing the tension on the cables 4|, 42, 43 and 44. In such case the buoys will be pulled slightly under water and the chains connecting them to the anchors will straighten out.

The cables 4|, 42, 43 and 44 pass through rotary chocks and thence to power winches such as that shown at 54. By adjusting the lengths of the cables with the winches the vessel 30 can be turned to any desired position within limitations depending on the geometry of the particular mooring. By this means the vessel 30 can be turned so that its longitudinal or streamline axis is directed into the wind. The mean position of the ship as determined by the positions of the four anchors should be that of the prevailing wind and the range of change of direction of the vessel should be sufficient to care for normal variations of the usual wind direction.

The vessel 30 should be of small beam compared to the distance between the platform [0 and the tower IT to minimize the possibility of the vessel being carried over against one of them in a storm. In addition, although the ship is of small beam compared to its length the length of the vessel should be substantially less than the distance between the platform l0 and tower I! to minimize the possibility of one end of the vessel swinging over against the platform in case it breaks loose from its moorings at one end. For example, as shown in the drawing, the vessel 30 is of a length equal to approximately twothirds the distance between the platform I0 and the tower I1. Since the platform [0 is the location of the construction work to be performed, e. g., oil well drilling, it is particularly important that the vessel never be allowed to contact the platform [0 and for this reason additional moorings may be provided. As shown in Figure 2 these side moorings comprise cables 55, 56 which are connected to spring buoys 51, 58 similar to the spring buoys of the main 4-point mooring, each being provided with a heavy chain and Bell anchor as shown at 59 and 60. The length and tension of the cables 55 and 56 can be changed by means of a power winch 6| to which either of the cables can be connected through a suitable block and tackle 62 and stationary pulley 63. For additional stability the usual bow and stem anchors 64 and 65 carried on chain 66 and cable 61 respectively, can be used.

The towers l6 and I! are preferably disposed so that a line drawn between them is at right angles to the direction of the usual wind and sea so that when the vessel 30 is moored therebetween heading into the wind the cable 20 will run athwart ship thereof. While it is usually preferable to place the tower IS on the platform I!) or immediately adjacent thereto so that the cableway operator in the tower 16 can be in immediate communication with the workmen on the platform I0 it is within the purview of the invention that the tower can be placed at some distance from the platform II). It is only necessary that the cableway pass over the top of the platform I0.

There is also some latitude with respect to the point along the length of the vessel 30 at which the cableway crosses for as long as the vessel 30 is of considerable length compared to the crest to-crest wave length of the rough sea normally encountered there will be very little pitch. However, it is preferable that the cableway 20 cross the vessel 30 directly amidship, in which case the pitch of the vessel will have practically no effect whatsoever andthe only motion noticeable will be a slight rise and fall and also perhaps a slight roll if the vessel is not headed directly into the wind. It is because of this comparative stability of the amidship section of a large vessel that it is possible to transfer men and materials from the skip 24 to the vessel 39 even in relatively rough weather.

In use of the marine edifice previously described the men will be housed on the vessel 30 and all the materials required for a normal drilling operation to the expected depth of the well will also be carried on the vessel. On the platform It there will be carried only enough men to operate the drilling rig and the cableway. Pipe, casing, and other materials will be transferred to the platform from the vessel 3:: as needed. Fluid materials will be pumped to the platform through the underwater conduits. In case of storm all the men can be removed from the platform to the vessel 30 and if a hurricane or other severe storm is predicted the vessel 30 may be disconnected from its moorings and taken to a place of shelter. For this purpose the connections between the cables 4|, 42, 43 and 44 and the spring buoys is preferably made of a quick attachable-detachable type. The flexible hose for the fluid conduits are also disconnected from the vessel, blanked off and buoyed so that re-connection can be made after the storm is over. The vessel 30 is preferably self-propelled but may in some cases be merely a barge which is towed to and from location with a tug.

While a preferred embodiment of the invention has been shown and described, many modifications thereof can be made by one skilled in the art without departing from the spirit of the invention and it is intended to cover by Letters Patent all forms of the invention falling within the scope of the appended claim.

I claim:

Apparatus for conducting ofishore marine operations comprising a structure built completely off shore on the marine floor and rising above water, a working platform supported above water on said structure, an elongated vessel, means for elastically mooring the vessel to the marine floor whereby the vessel can move without breaking loose its mooring but is constantly restrained from motion, means on said vessel for adjusting said mooring means to keep the vessel headed into the wind whereby to minimize rolling of the vessel, said vessel having a length of about two hundred feet at least whereby the vessel can span the crests of the longest calm and normal rough weather ocean waves to minimize rise and fall and pitching of the vessel, a pair of structures built on the marine floor and rising above water, two towers supported one on each of said pair of structures, said tower supporting structures being spaced apart with said platform and the amidships section of the vessel in between and in line therewith, the distance from the amidships section of the vessel to the nearest one of said platform and tower supporting structures being greater than half the length of the vessel whereby as the vessel is turned to head into the wind it will always be clear of said structures, said line between the tower supporting structures being perpendicular to the direction of the prevailing wind whereby the vessel when headed into the wind will as nearly as possible always be at right angles to said line between said pair of tower supporting structures with its narrowest part in the direction of the line between said pair of structures and its bow and stern far removed from said pair of structures and said platform supporting structure, a high line supported on said towers running over the platform and over the amidships section of the vessel where the vessel is most nearly stationary, a skip supported on the high line, and means to move the skip up and down and along the high line between the vessel and platform whereby men and materials can be conveyed between said vessel and working platform in all weather except severe storms and hurricanes, said towers supporting the highline above the highest point of the vessel whereby the vessel is entirely clear thereof and can be moved freely therebeneath when the skip is raised away therefrom, said mooring means being releasable whereby the vessel can be moved out of the path of a storm, said structures for supporting said platform and towers being of openwork construction to allow high velocity fluids to pass therethrough without damage to said structures.

ROSS WHITE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 89,794 Rowland May 4, 1869 281,446 Brown July 17, 1883 387,794 McDonald Aug. 14, 1888 551,506 Miller Dec. 17, 1895 676,626 I-Ioshor June 18, 1901 726,685 Holbrook Apr. 28, 1908 874,223 Miller Dec. 17, 1907 919,178 Johnston Apr. 20, 1909 949,961 Morris Feb. 22, 1910 2,512,783 Tucker June 27, 1950

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