US3118408A

US3118408A - Float for use in water

Info

Publication number: US3118408A
Application number: US212258A
Authority: US
Inventors: Richard P Knapp
Original assignee: Jersey Production Research Co
Current assignee: Jersey Production Research Co
Priority date: 1962-07-25
Filing date: 1962-07-25
Publication date: 1964-01-21
Anticipated expiration: 1981-01-21

Description

Jan. 21, 1964 R. P. KNAPP 3,118,408

' FLOAT FOR USE IN WATER Filed July 25, 1962 v 2 Sheets-Sheet 1 FIG l. lo

INVENTOR.

RICHARD P. KNAPP,

Jan. 21, 1964 R. P KNAPP 3,1

FLOAT FOR USE IN WATER Filed July 25, 1962 4 2 Sheets-Sheet 2 INVENTOR. RICHARD P. KNAPP,

ATTORNEY.

United States Patent 3,118,408 FLOAT FOR USE IN WATER Richard P. Knapp, New Orleans, La., assignor, by mesne assignments, to Jersey Production Research Company, Tulsa, Okla, a corporation of Delaware Fiied July 25, 1962, Ser. No. 212,258

7 Claims. (Cl. 114.5)

The present invention is directed to a float or buoy tor use in water that may be disturbed by waves. More particularly, the present invention is concerned with a float or buoy which minimizes the force of wave action. In its more specific aspects, the present invention is directed to an underwater or surface float or buoy which may be employed in various types of marine operations.

The present invention may be briefly described a a buoyant member formed by four equal diameter cylinders joining each other at right angles to form a plan of concentric squares in a single plane with a distance of at least two diameters between axes of parallel cylinders.

The buoy-ant member of the present invention may suit ably be employed to support a platform from which various marine operations may be performed. The buoyant member may suitably be provided with means for anchoring it and its supported equipment at a water location. For example, the bouyant member may be employed as a foundation to support a mobile drilling platform for conducting oil exploration and production operations therefrom, and may be provided with means for anchoring the foundation at a selected water location from which the structure may be moved a desired.

The buoyant member of the present invention may be constructed of buoyant material or it may be constructed of nonbuoyant material and suitably compantmented to obtain buoyancy therein. The compartments may be interconnected and may be provided with conduits for adding or removing ballast from the compartments. Thus, the buoyant member may be at least partially hollow or may be formed of buoyant material. The present invention may suitably be used when a negative buoyancy is provided. For example, it may be used suspended from another member having positive buoyancy and formed in accordance with the present invention with the suspended member having a negative buoyancy but yet being of a configuration such that minimum drag thereon is provided.

Various types of underwater floats or buoys have been used in marine operations. These underwater floats or buoys which have been used heretofore all present a prob lem with respect to wave drag. These floats or buoys require moorings or other positioning devices to maintain a useful position and to limit motion in a seaway. The present invention provides a new and improved type of float or buoy which minimizes the force of wave action that tends to move buoys or floats in a seaway. The present invention, which involves a float made up of four equal diameter cylinders joining each other at right angles to form a square torus having a plan of concentric squares in a single plane with a distance of two diameters or more between axes of parallel cylinders, has been found unexpectedly to minimize the force of wave action when exposed thereto. Thus, a float or buoy in accordance with the present invention encounters substantially less force value in waves than other floats exposed to waves of the same magnitude.

The present invention will be further illustrated by reference to the drawing in which:

FIG. 1 is a plan view of a float in accordance with the present invention.

FIG. 2 is a section taken along the lines 2--2 of FIG. 1 which is one axis of symmetry of FIG. 1.

FIG. 3 is a perspective view showing a float of the pres- 3,118,463 Patented Jan. 21, 1964 ent invention being used as an underwater buoy in drilling operations.

FIG. 4 is a similar enlarged view to FIG. 3, showing the float used both as a surface and underwater buoy.

FIG. 5 illustrates the float being used as a support for a floating platform.

FIG. 6 illustrates the bridle attachment employed in FIGS. 3 and 4.

Referring now to the drawing and specifically to FIG. 1, numeral 10 generally designates the float made up of

equal diameter cylinders

11, 12, 13, and 14. The cylinders 11, 1-2, 13, and .14 are joined together and terminate at their intersections as shown. The cylinders I l, 12, 13, and 14 may he at least partially hollow to provide suitable buoyancy to the float 10, as shown in FIGS. 1 and 2. While the float of the present invention may be partially hollow to provide buoyancy thereto, it is contemplated that the present invention may be constructed of buoyant material and therefore need not necessarily be at least partially hollow. The side of the float of the present in vention is indicated as having a length equal to the distance L, while the distance between axes of parallel cylinders as shown in FIG. 2 is L minus D. In all instances, the distance between axes of parallel cylinders must be at least two diameters. In other words, the distance L minus D must always be equal or greater than 21). Stating this otherwise, L equals or exceeds 3D. The diameters of the cylinders may vary greatly. For example, the diameters of the cylinders will be selected for the particular use to which the float will be put. Floats made up of cylinders having diameters ranging from about one inch to about 100 feet may be employed.

Referring now to FIG. 3, a mobile drilling vessel such as provided with a drilling rig, generally indicated as 21, is in a body of water 22 with a drill string 23 extending from vessel 20 and a casing 24 penetrating the water bottom 25 and extending into the sedimentary material 26. In order to locate the vessel 20, it is sometimes necessary to provide suitable markers. An ordinary vessel mooring is impractical in waters having great depth and, in these particular instances, a vessel such as 20 may be held at a particular location by propulsion means on the vessel. In this instance, a plurality iof radar reflectors, such as 27 may be provided with the radar reflectors connected by means 28 to buoys 29 which, in turn, are connected by lines 30 to underwater buoys 31. In the showing of FIG. 3, the

buoys

29 and 31 are formed, in accordance with the present invention, of four equal diameter cylinders joining each other at right angles to form a plan of concentric squares in a single plane with a distance of at least two diameters between axes of parallel cylinders. In the showing of FIG. 3, the vessel 20 is provided with radar equipment 32 from which signals are obtained from radar reflectors 27. The vessel may be also or alternatively provided with sonar equipment 33 which transmits signals to sonar transponders 34 on the buoys 31 and receives signals from sonar transponders 34. Thus, with a plurality of radar or sonar transponder signals, it is possible to locate vessel 20 accurately. The present invention is quite useful'in such operations in that the buoyant member, formed in accordance with the present invention, minimizes the horizontal drag force of wave action and permits the buoys to remain in a substantially con stant location which allows the vessel 20 to be properly located. As shown in FIG. 3, this allows drilling operations to be conducted in waters of great depth.

Referring now to FIG. 4, the floats of FIG. 3 are shown in more detail with the floats 31 being attached by flexible lines 35 to anchors 36 on the bottom 25, the

floats

31 and 29 being interconnected by flexible lines such as 37.

Bridle arrangements

38 and 39 may be employed on float 31, and a bridle arrangement such as 40 may be used on a float 29. The radar reflectors 27 may be suitably supported on a staff 41, which may be suitably braced by bracing members 42.

Referring now to FIG. 5, another embodiment of the 4 61 attached to

points

63 and 64 as seen more clearly in FIGS. 1 and 6.

In order to illustrate the invention further, platform models supported by equal volume floats of various conpresent invention involves a buoyant member such as has figurations were tested in a wave tank employing waves been described with respect to FIGS. 1 and 2. In this of equal characteristics. The drag on the several floats particular instance, a buoyant member 50 has attached was compared with the results as shown in the following thereto vertical supporting members 51 and cross-bracing table:

Table I Wave #1 Wave #3 Model Plan Section A-A lleight 0.5 Height .21

Length 0.28 Length 7.21 Water Depth 2.0 Water Depth 2.0 Drag Drug c (h A 4 Cylinders 4-1 33 A A Hollow Square 1-1 J 27 29 Square 'lorus: A A

=11.25" D=3.22 L.,. 18 in S uarc Torus: A- A q L=1-i.42" D=2A0 L... ....3 G11}: 7 1

Square Torus: A A

L=1S.05 D=2.n" L... b ca 0 o A A Hollow Cylinder L.@ J 18 A A Torus L t QIIQ Q3 23 1 Average force values compared on basis of model having the smallest average force as percent greater.

members 52 which support a platform 53 which, in turn, may support other equipment such as equipment used in well drilling operations. The buoyant member may be suitably anchored to the water bottom 54 by anchors 55 spaced outwardly from the buoyant member 50 and attached thereto by flexible lines 56 which may be attached to the four corners of the buoyant member 50. It is to be understood that other anchoring means may be employed and that a single line may be used to anchor the buoyant member 50. Likewise, while the anchors 55 have been shown as being spaced outwardly from the buoyant member 50, the anchors 55 may be anchored under the buoyant member 50 as may be desired or at any location. It should be noted that when anchors 55 are located outside the perimeter of float 50, the approach of a wave causes inclination of the platform 53 to increase the angle between the platform and the water surface, whereas the location of anchors 55 inside and below the perimeter of float 50 during an approach of a wave results in inclination 'of platform 53 to decrease the angle between the platform and the water surface. It will be noted with respect to FIG. 5 that the buoyant member 50 may be submerged with respect to water level 57 or may be floating at water level 57' as indicated by the dotted line. It will be preferred, however, to employ the buoyant member 50 submerged since wave drag decreases when employing the buoyant member of the present invention submerged.

Referring now to FIG. 6, a buoyant member such as 10 is provided with a bridle, such as 39 and 38 as described in FIG. 4, made up, respectively, of lines 60 and It will be noted from the data in the foregoing table that the square torus buoyant member of the present invention provides less drag than a float which is a hollow square or a hollow cylinder or a torus. Likewise, a float made up of four cylinders has greater drag than the buoyant member of the present invention. In the several floats compared in Table I, all floats or combinations of floats were of equal volume and thus the results are on a comparative basis.

The present invention is quite advantageous and useful and may be employed in any marine operations besides those given by way of illustration only.

The nature and objects of the present invention having been completely described and illustrated and the best mode and embodiment thereof set forth, what I wish to claim as new and useful and secure by Letters Patent is:

1. A marine structure comprising a buoyant member formed of four equal diameter cylinders joining each other at right angles to form a plan of concentric squares in a single plane with a distance of at least two diameters between axes of parallel cylinders, support means connected to said buoyant member and spaced to extend above said buoyant member, and means connected to said structure for anchoring said structure such that said buoyant member is submerged at a marine location.

2. A marine structure comprising a buoyant member formed of four equal diameter at least partially hollow cylinders joining each other at right angles to form a plan of concentric squares in a single plane with a distance of at least two diameters between axes of parallel cylinders, support means connected to said buoyant member and spaced to extend above said buoyant member, and means connected to said structure for anchoring said structure such that said buoyant member is submerged at a marine location.

3. A marine foundation comprising a buoyant member formed of four equal diameter cylinders joining each other at right angles to form a plan of concentric squares in a single plane with a distance of at least two diameters between axes of parallel cylinders, a platform vertically spaced above and supported on said buoyant member, and means connected to said foundation for anchoring said foundation at a water location with said buoyant member submerged.

4. A marine foundation comprising a buoyant member formed of four equal diameter at least partially hollow cylinders joining each other at right angles to form a plan of concentric squares in a single plane with a distance of at least two diameters between axes of parallel cyl inders, a platform vertically spaced above and supported on said buoyant member, and means connected to said foundation for anchoring said foundation at a water location with said buoyant member submerged.

5. A marine foundation comprising a buoyant member formed of four equal diameter cylinders joining each other at right angles to form a plan of concentric squares with a distance of at least two diameters between axes of parallel cylinders, a platform, support members interconnecting said platform and said buoyant member in vertically spaced-apart relationship, anchor means adapted to be placed on bottom of a water location, and at least a flexible member interconnecting said buoyant member and said anchor means to anchor said foundation and submerge said buoyant member.

6. A marine foundation comprising a buoyant member formed of four equal diameter at least partially hollow cylinders joining each other at right angles to form a plan of concentric squares with a distance of at least two diameters between axes of parallel cylinders, a platform, support members interconnecting said platform and said buoyant member in vertically spaced-apart relationship, anchor means adapted to be placed on bottom of a Water location, and at least a flexible member interconnecting said buoyant member and said anchor means to anchor said foundation and submerge said buoyant member.

7. A marine structure comprising a buoyant member formed of four equal diameter cylinders joining each other at right angles to form a plan of concentric squares in a single plane with a distance of at least two diameters between axes of parallel cylinders, support means connected to said buoyant member and extending above said buoyant member, said buoyant member being adapted to float in a body of water, a second member having a negative buoyancy formed of four equal diameter cylinders joining each other at right angles to form a plan of concentric squares in a single plane with a distance of at least two diameters between axes of parallel cylinders, said second member being spaced below said buoyant member in said body of Water, means interconnecting said buoyant member and said second member, and means connected to said second member for anchoring said structure such that said second member is submerged in said body of water.

Day Ian. 15, 1846 Marsh Oct. 13, 1959