US2472869A - Island for well drilling - Google Patents

Description

Jim@ M w. J. TRAVERS, JR 2,4?28

l v ISLAND FOR WELL DRILLING Filed Feb. 24, 19m l 2 sneaks-sheet 1 June i4 1949i w. .5. TRAVERS, JR K ,472,59

` ISLAND EoR WELL DRILLING Filed Feb. 24, 1 947 2 sheets-sheet 2 gul 38 l lMil 40 mi il@ "mail" ummm `device being built on low ground behind an arti- Patented June '14, 1.949

ISLAND Fon WELL'DRIILING William J. Travers, Jr., `Los Angeles, Calif.,v assignor to Richfield Oil Corporation, Los Angeles, Calif., a corporation. of Delaware Application February 24, 1947, Serial No. 730,337

4 Claims. l

This invention relates to an artificial island for the drilling of wells from offshore marine locations or for supporting well drilling apparatus above any body of water of relatively vshallow depth. This invention is particularly directed to a method of installing an artificial islandl in a .desired location and to an artificial island structure particularly well adapted for supporting well ldrilling apparatus.

The principal object of this invention is to provide a normally buoyant structure having a central opening, the structure being sinkable to rest on bottom with a portion of the structure projecting above the `water level and in which the central opening may be filled with waterdisplacing material resting on bottom to prevent lateral shift of the structure.

Another object is to provide an improved method of constructing a normally buoyant structure and positioning it at a desired location on bottom in a body of water with a portion of the structure projecting upwardly beyond the water level.

Another object is to provide an articial drilling island comprising an annularfring having a central opening, the ring'being normally buoyant to permit the ring to be floated to position and being sinkable to rest on bottom.

Another object is to provide such a ring structure having concentricinner and outer upwardly extending walls joined by an annular oor, the floor being reinforced by radially extending beams formed integrally with the walls and floor to resist deection of the oor while the structure is being oated to'position.

Another object is to provide a ring structure of this type `having a plurality of upwardly extending pipes through which a plurality of wells may be drilled. the pipes being spaced at intervals around the annular iloor.

' Another object is to provide an artificial island for supporting drilling apparatus which is iloate able to position and'which is adapted to resist action of waves, tide, weather and storms for a period of years until depletion of wells drilled from the island and which may then be reiloated if desired for removal to some remote point.i

Otherobiects and advantages will appear hereinafter. l

In the drawings: v l

Figure 1 is a perspective view. partly lbroken away. showing construction of a preferred form of 'artiiicial island embodying my invention, the.

cial dam adjacent tide water;

Figure 2 is a.' perspective view partly broken away showing the artiiicial island being noated to position;

Figure 3 is an elevation showing the island resting on bottom and a plurality of wells being drilled simultaneously; and

Figure 4 is a perspective view partly in section showing the artificial island resting on bottom and illustrating a preferred' form of contour of the upper surface ofthe island during well drilling operations.

Referring to the drawings, the ring structur generally designated Iii may preferably be constructed behind a temporary dam Il adjacent tide water. The ring structure maybe of any convenient or desirable shape and is provided witha central opening i2. As shown in the drawings, the opening I2 is defined by an inner upstanding circular wall I3. This wall I3 is encircled by an outer upstanding circular wall I4 defining an annular space I5 between the inner y and outer concentric walls I3 and Il.

\ vAn annular floor I6 extends between the walls I3 and. I4 near the lower ends thereof and is forcements I8. Bands I9 may be provided on ,tionalstin'ness v It is contemplated that the entire structure theinn'er surface of the outer wall I4 for so far described may be 4:formed of reinforced concrete. Steel reinforcement members are not shown in the drawings, although it is to be understood that suchsteel reinforcing will be included in the manner taught by conventional practice.

Concrete forms 20 are shown diagrammatically in Figure` 1, illustrating a preferred manner of forming the outer wall I4, but it is recognized that these formsmay take any convenient or desirable shape and may be constructed-of wood, metal or othermaterials. It will be noted that the upper 1 portion of the outer' wall i4 is iiared outwardly.

as lshown atQIZI,v for a purpose to be later described.

surface thereof and .these pipesarearranged in the annular .space I5 between `the inner and outer vwalls y113 and. Il. Suitable interconnecting bracing is provided' formaintaining the pipes addi- 3 22 in position, and additional lateral tie rods 24 may be provided.i1,l desired.

When the reinforced concrete structure thus described is complete. the temporary dam II is removed to allow tide water to encircle the structure. The proportions of the structure are such that it oats with only a relatively small portion of the outer wall I4 submerged.

Figure 2, which is partly broken away, shows the buoyant ring being floated to position and one or more tugs 25 may be provided for towing the ring to the desired location.

-An important advantage of the annular buoyant structure just described resides in the provision oi the central opening I2. If this opening were to be omitted and the iloor I6 continued completely across the structure in circular form, the buoyant forces acting on the floor I6 would require reinforcing beams I1 of greatly increased size in order to provide sumcient stiffness over such an increased span. Floor beams of such large size would be seriously detrimental in that the increased weight would more than onset the increased buoyancy with the result that the structure would float much lower in the water. and the hazard of capsizing or foundering before reaching the desired location would be greatly increased. Furthermore, the additional cost of greatly increasing the size of the oor beams would be economically disadvantageous.

When the annular buoyant structure is positioned over the desired drilling location, the ring is sunk to rest the bottom surface of the floor I6 on the bottom of the ocean door 28. This is accomplished by admitting water into the annular space I by means (not shown). Subsequently this water may be displaced by illling the space I5 with sand or rock dredged from the ocean floor. Additional sand or rock 21 is deposited within the central opening I 2 and acts as a core or plug resting on the ocean floor 28 to prevent lateral shift of the entire structure. When the ring is resting on bottom, any convenient form of top surface is constructed over the annular space I5 between the walls I3 and I4 and over the central opening I2.

As shown in Figure 4, the upper surface of the structure may be formed by concentric concrete pads and walls forming an annular scupper 28,

an annular ditch 28 and flat ring surfaces 30 and 3 I separated by the annuius 32. The pipes 22 project upwardly into the annulus 22.

A central depression 32 is provided by the horizontal pad 34 extending over the central opening l2 and over a portion of the annular space I5. This central depression 8l is adapted to accommodate the usual pumps 3S for circulation of drilling fluid employed in the rotary process of drilling wells. Mud tanks 88 are also contained within the depression 23 for storing, settling and mixing of such mud fluid as will be readily understood by those skilled in the art.

The annular structure I8 is formed of sumcient size to accommodate a plurality of well drilling derricksv and their associated equipment for simultaneous drilling of a plurality of wells. Each of the derricks 21 is mounted on a substructure 38 and is provided with the usual engine house 38 and pipe rack 48.- Each of the derricks 31, together with its associated drilling equipment comprises a unitary assembly hereinafter designated 4I.

Each of the drilling assemblies 4| is supported on the upper surfaces oi' the structure I0 and may rest on the annular pads I0 and 3 I if desired.

curing each of the assemblies in selected position so that a plurality of wells may be drilled simultaneously. Each of the derricks 81 is centered over one of the pipes 22 and the drill string 42 operates through the particular pipe 22 selected for drilling a well. Conventional techniques for slant drilling are employed so that a relatively large area o! formation may be exploited from the relatively small area of the single artificial island Il.

After each individual well is completed, the drilling unit 4I is moved to position over one of the other pipes 22. As an example of the relative size of operations to .be conducted from such an artificial drilling island, it is contemplated that with a particular embodiment of my invention over one hundred wells may be drilled from an island of approximately two hundred feet outside diameter and that as many as four drilling units may operate simultaneously.

'I'he flaring portion 2| at the upper end of the outer wall I4, together with the circular rim 43 provides the scupper 28 for collecting any water which comes over the edge of the outer wall due to wave action or storms. Water passing over the upper edge of the outer wall flows into the scupper 28 and passes outwardly through ports 44 and drainage openings 48 back into the sea. The annular ditch 28 is also connected to the drainage passageways 48 so that water passing the scupper 28 is also trapped and returned. The flaring portion further acts as a defiector to prevent waves from breaking over the wall I4.

When the drilling of -wells has been completed, the drilling units 4I. including th'e'vderricks 31, are dismantled and withdrawn from the artificial island and the tanks Il a'nd pumps 35 are likewise removed.

Conduits (not shown) are provided for conveying the oil produced from the wells to shore for disposal since, under ordinary circumstances, it is contemplated that oil will not be stored on the island. Any suitable means for producing the oil, such as natural ilow, gas lift, plunger lift, sucker rod, etc. may be employed for raising the oil to the surface through the pipes 22.

After a period of years. the oil strata will be depleted to the point where it is not economically feasible to continue productive operations. At such time the island could be converted into a park for recreational purposes, small boat anchorage, etc., and if such use is adopted, the scupper 28 can be used, if desired, for ornamental planting of trees, such as the palm trees 48.

It is to be understood that the ornamental trees and other recreational faculties may not be installed onrthe island until after removal of the well drilling units 4I.

If it is desired to remove the island at the end of its period of usefulness, the annular space I5 between the walls I3 and I4 may be evacuated and thereby again render the structure buoyant. The structure thus retloated may be towed to any desirable point for scrapping or disposal in some other manner.

It is contemplated that the use of reinforced concrete for the side walls and iioor of the structure will be suillciently resistant to wave action, weather and chemical erosion to remain in service during the useful productive period in withdrawing oil-from the vstrata below the ocean oor.

While the structure Il has been shown and described as annular in'shape, it is recognized that either the inner wall I3 or the outer wall Il. or both could be polygonal in shape rather than circular, the only essential requirement being that a central opening can be provided.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth, but my invention is of the full scope of the appended claims.

I claim:

l. A device for supporting well drilling apparatus in an offshore marine location, comprising in combination: inner and outer concentric upstanding wallsy joined by `an annular oor, the inner wall dening a central opening completely through the device, the annular space between the walls being filled with material to sink the ring and thereby hold it on bottom with the outer wall extending above the water level, and the central opening being filled with Water-displacing material resting on bottom to thereby resist lateral shift of the device.

2. A device for supporting well drilling apparatus in an offshore marine location, comprising in combination: inner and outer concentric upstanding walls joined by an annular floor, the inner wall dening a central opening completely through the device, the annular space between the walls being lled with material to sink the ring and thereby hold it on bottom with the outer wall `extending above the water level, a plurality of upwardly extending pipes spaced about theannular floor through which wells may be drilled, and the central opening being filled with waterdisplaci-ng material resting on bottom t thereby resist lateral shift of the device.

3. A device for supporting well drilling appara'- combination: inner and outer concentric upstanding walls joined by an annular floor, the inner Wall dening a central opening completely through the device, the annular space between vthe walls being lled with material to sink the in combination: inner and outer concentric upstanding walls joined by an annular floor, the

' inner wall defining a central opening completely tus in an offshore marine location, comprising in through the device, the annular space between the walls being lled with material to sink the ring and thereby hold it on bottom with the outer wall extending above the water level, and the central opening being filled with water-displacing material resting on Abottom to thereby resist lateral shift ofthe device, and a plurality of reinforcing beams extending radially on said annular oor from said inner to said outer walls.

' WILLIAM J. TRAVERS. JR.

REFERENCES CITED VThe following references are of record. in the` le of this patent:

UNITED STATES PATENTS Number Name f Date 875,699 Dumais Jan. '7, 1908 1,465,664 ('iriesser Aug. 21, 1923 1,856,312. Bradshaw May 3, 1932

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