US2677935A

US2677935A - Submarine drilling platform

Info

Publication number: US2677935A
Application number: US143681A
Authority: US
Inventors: Herbert J Schaufele
Original assignee: Signal Oil and Gas Co
Current assignee: Signal Oil and Gas Co
Priority date: 1950-02-11
Filing date: 1950-02-11
Publication date: 1954-05-11
Anticipated expiration: 1971-05-11

Description

y 1954 H, J. SCHAUFELE 2,677,935

SUBMARINE DRILLING PLATFORM Filed Feb. 11, 1950 5 Sheets-Sheet l A r TOKNE y- May 11, 1954 H. J. SCHAUFELE 2,677,935

SUBMARINE DRILLING PLATFORM Filed Feb. 11, 1950 5 Sheets-Sheet 2 V I I I II i w m 39 39 I I s I I I 9: v

J JNVENTOR. HERBERT l]. lsdmuFiLE May 11, 1954 H. .1. SCHAUFELE 2,677,935 SUBMARINE DRILLING PLATFORM Filed Feb. 11, 1950 5 Sheets-Sheet 5 IN V EN TOR. HERBER T J Sal-In UF'EL E ATTORNEY.

y 1954 H. J. SCHAUFELE SUBMARINE DRILLING PLATFORM 5 Sheets-Sheet Filed Feb. 11, 1950 INVENTOR. UFELE HERBERT (I SCH!) May 11, 1954 H. J. SCHAUFELE 2,677,935

SUBMARINE DRILLING PLATFORM Filed Feb. 11, 1950 5 Sheets-Sheet 5 WH'TER LEVEL 1N VEN TOR.

HERBERT JCHHUFI'LE A TTORNE y.

, others have devised Patented May 11, 1954 Herbert J. Schaufele, Lon

to Signal Oil and .Gas

Califi, a corporation of g Beach, Calif., assignor Company, Los vAngeles, Delaware Application February'll, 1950, Serial No. 143,681

19 Claims. I

This invention relates to a structure for submarinedrillin platforms, including in the term submarine the bottoms under oceans, :seas, bays, harbors, roadsteads, lakes, estuaries, and other waters where such structures are .to be erected.

The-problem'of devising a drillingplatformto be erected in submarine bottoms which can be economically erected on a drilling site and which will form a .safe and stable platform in heavy weather has not, to .applicants knowledge, been satisfactorily solved. Efforts have been made to devise structures which may be erected at the site, others have used structures of prefabricated sections which may beassembled at the site, and structures which may be prefabricated and transported as a unit. Various means of transportation over water and methods for-erection at-the site have'been suggested. In some, the units are transported on barges and pontoons and others have employed flotation tanks.

I have devised an improved, simple, and relatively inexpensive structure which 'may be fabricated and floated to the marine locations and erected to form a stable drilling base which may be used either for a single or for a multiple well location. The structure may be of minimum height suilicient 0 raise the deck of the platform above wave action so as to permit waves to pass underneath the deck without exerting any'serious uplifting force on the deck structure and present a minimum surface against which wave pressure may be exerted. Means are provided whereby a stable foundation may be formed for the structure.

The structure of my invention consists of a plurality of vertical members with suitable bracsubstantial size extending from near the top to'near the bottom of the structure. The conduit extends longitudinally of the column and maybe closed at the bottom and if desired at the top to form an elongated chamber extending longitudinally of the column. Means may be provided to flood conduit with water to control the buoyanceof the system. Additional buoyancy control means are provided which also will act to adjust the center of gravity of the structure. Thus a buoyancy tank is provided near the bottom of the structure and'means are provided to flood the lower tank with water to control the buoyancy and center of gravity.

The conduit also may .be used as a means for erecting and stabilizing the construction. Thus means ar provided for opening the bottom end of the conduit and for passing'excavating means through the conduit'to remove mud and earth from beneath the structure to permit of forming a good footing for thestructure. The conduit also makes it possible to introduce cement for the purpose of establishing a foundation for-the structure.

As a. permissible and, -I believe, highly-desirable feature, I make the bottom of the tank wedgeshaped; thus'it may be'conical. I intersect the conical bottom of the tank with the conduit. Thus, in elfect,'the'bottom.forms=a flared mouth for the conduit and thus :the cement forms a footing for the structure.

This stabilizing means, which, if desired, may be added to by means of piling driven through the tubular vertical members of the structure, stabilizes the'structure'in an economical, simple and eflicient'manner. The structure is thus stable and also removable. Thus, the'-structure may be removed from the well site by cutting the piles and after unloading the tanks and -buoyancy conduit, the structure may be floated-off its concrete base. The vertical members, if tubular, may also be used-as jet pipes to assist in the'erecting of the structure, and also when thestructure is to be removed, they assistiinbreaking the adhesion of the structure'in'the-earth or mud, and in freeing it and thus in the removal thereof.

These and other objects of my invention will be further described by reference to the drawings, in which Fig. 1 is an elevation of my structure;

Fig. 2 is an irregular section taken on line 2-2 of Fig. 3;

Fig. 3 is a plan view;

Fig. 4 is a section taken-on :line 4-4 of Fig. 2;

Fig.5 is a'section taken'on line 55 ofFig. 2;

Fig. 6 is a section taken-on linet-G of Fig. '2;

Fig. '7 is a detail of Fig. 1;

Fig. 8 is a section similar to Fig. 2 but showing the superstructure;

Fig. 8a is a fragmentary section of the leg structure with the pile in position; and

Figs. 9 to 15 show various stages in the erection of the drilling tower of my invention.

The structure as shown in Fig. 1 comprises a ring of tubular vertical leg :members I. They surround a centrally disposed vertical caisson -2. The members I are connected to the caisson 2 by means of radial braces 4 (Fig. 5) and chordal bracing members 3 (Figs. land 5) at several verti'cally spaced planes along the vertical memhere. At the top of the structure the floor 6 is supported on the members I by means "of a preand lower frame membefore erection does not 5, 5 and 6 and fabricated truss bracing bers 5. The structure carry the deck superstructure appears as indicated in Fig. 1.

At the bottom of this structure I provide a tank having an inclined bottom at an acute angle to the center line of the structure and of the central caisson 2. Where, as in the form shown in Fig. 2, the tank is disposed across the whole bottom and is annular, the bottom may be conical.

Thus, as is shown in Fig. 1, the tank is circular in section and encompasses the vertical members I with the caisson 2 centrally disposed of the annular tank so that the caisson passes through the central opening of the tank. The bottom I is conical in the shape of a truncated cone intercepted by the central caisson 2. The bottom of the tank is thus a flared opening connected to the central caisson 2. The tank is provided with a dome-shaped doughnut top 8 and sides 9. Vertical conduits l0 pass through the tank and the bottom '1 and top 8, making a water-tight connection with. said top and bottom. The tank is internally braced by means of suitable angular bracing IE and radial bracings l2 and chordal bracing H3. The lower corner of the tank formed by the juncture of the bottom 1 and the side 9 is reinforced by a hardened ring-cutting shoe 9 which is welded to the bottom and sides of the tank.

The top of the central caisson 2 is closed by a removable bonnet Ill suitably bolted by means of flanges to the caisson 2. Inside the caisson 2 and underneath the bonnet M I provide a spider l5, and near the bottom of 2 I provide a circumferential ring IS welded to the interior of the caisson 2. Spaced 90 apart I weld locking brackets I! underneath the ring I5. The brackets I! carry stops in the form of depending perpendicular edge ridges l8 and is.

The locking spider 20 has four arms 2! spaced 90 apart, each arm having an upstanding edge 23. A central hub 22 is also provided. The spider edge 23 fits inside the ridge l8 and abuts against the ridges [9.

A valve member 23 in the form of a dished plate having a downwardly formed lip 24 and a hub 25 is placed on the ring it. The ring [6 and the dished plate form a water-tight seal when the dished plate is clamped against the ring. To effect this clamping action, a stud 26 is welded or otherwise rigidly affixed in the hub 22 and passes through the hub 25. A wheel 28 is screwed onto the stud 2s and locked in place by nut 26a which is screwed on top of the stud 26. A pipe 29 is welded to the wheel 28 and is j ournalled in the hub 33' of the top spider l5. A shoulder 3| on the pipe 23 bears on top of the hub 30. A plug 31 with a square head is spot welded or otherwise secured to the top of the pipe 29.

A line 32, opening to atmosphere or water, is connected near the base of the caisson 2 above the plate 23'. A valve 33 on line 32 is actuated by a long rod 34 journalled near the top of the caisson 2 in a bracket 35 and actuated by a wheel 31.

Spaced 90 apart and positioned near the bottom corner where the bottom 1 joins the side 9 are four pipes 33 also opening to atmosphere or the water and having a valve 39 actuated by a long stem C 0 suitably supported at the top of the structure and actuated by a hand wheel 4|. Four air vent lines 42 ar connected 90 apart to the top of the convex doughnut-shaped roof 8 of the tank. Each line carries valve 43. A valved air vent M is positioned in the bonnet l4. This construction results in an elongated buoyancy chamber extending longitudinally of the structure and disposed centrally thereof, with a removable closure near the lower end thereof and a closure at the top thereof.

To erect the structure which may be assembled on shore, the structure as shown in Fig. 2 and as described, with the

superstructure

5, 5, and 6 removed, is assembled with the valve disc 23' in clamped position against ring [6 and with bonnet M in position and

valves

33, 38, 43, and 44 closed and the plugs I in position. The structure is floated on its side (see Fig. 10).

In employing the plugs l, the leg members I are thus partly filled with water but retain a large air chamber which thus acts to add buoyancy to the structure. However, with a sufficiently large caisson or tank, this added buoyancy is not necessary. I, therefore, in such case, omit the plugs I and instead, while the structure is on shore or after it is floated, I thread the piles 46 to be employed through the tubular legs I so that the ends of the piles are Within and close to the end of the legs I. The piles which are preferably tubular are held in position in the legs I by a bolt 41.

The buoyancy of the structure is attained by reason of the air filled lower tank and caisson 2. The size of the chamber and pipes is preferably, but not necessarily, such that the caisson 2 floats in the water in a horizontal position.

The caisson terminates above the bottom of the structure. In order to provide buoyancy for the lower end of the structure the bottom tank is provided. It will also be observed that the structure is symmetrical and will float on even keel.

When the structure is towed to the desired location I may, by means of the tow line or by bottom anchor, hold the structure in approximately the desired location. If desired I may employ a derrick barge so that the hoist line of a boom derrick may be connected to the top of the structure. The valves 38, which are submerged, are opened and the valve 43 on the line which is in the air is opened. Water enters the lower tank and the tank end of the structure sinks. As the caisson becomes covered with water its buoyancy increases and the upper end of the structure emerges from the water, unless water is admitted to the caisson to control the buoyancy.

Since, as is desirable, the lower tank is of limited capacity, determined primarily by the requirement designed to add flotation characteristics to the lower end of the structure below the end of the caisson, and due to the large buoyancy of the chamber of the caisson 2, it will be desirable to flood a portion of the volume of caisson 2 in addition to the flooding of the lower tank. This is accomplished by opening valve 33 and bleeding air through 44. Water enters into the tank and caisson and its rise is controlled by the bleeding of the air valves. The structure thus pendulums about its center of buoyancy about the boom, if that is employed, and floats vertically in the water. The percentage of the structure so immersed is determined by the amount of water entering the tank and particularly the caisson 2.

It is to be observed that it is desirable when this is accomplished that the structure in its vertical position be off bottom.

It will also be observed that when this is accomplished the water level in the caisson 2 will be below the water line, and the air thus be under some hydrostatic pressure, that is, there is residual buoyancy in the tank.

The degree of buoyancy may be additionally controlled by connecting the valve 54 and line 42 to valve 43 to an air compressor on the barge so that air may be bled from caisson 2 and tank, or air introduced to blow out some of the water in the caisson or tank. In this way the structure may be held off bottom in a floating and vertical position steadied, if desired, by bottom anchors or tow lines or a derrick boom 45.

With the structure in such position, the plugs I, if used, are removed and piles 4t are dropped through the tubular members i. If the piles have been previously threaded through the lugs, the bolts 47 are removed. With the structure floating in a vertical position or with the piles held in a vertical position, the piles are driven into the submarine bottom by means of a pile driving or derrick barge anchored alongside the structure. It will be observed that the feature of this invention whereby the piles are carried in threaded position in the legs is a highly advantageous one. For example, if the structure requires 100 to 200 feet of pile and is riding 2G to 50 feet out of the water, the problem of upending and lifting a 120-foot pile so its lower end is 20 to 50 feet and threading this through the leg in an open body of water, presents a practioal difficulty in operation. This is avoided by the proposed method of pre-threading the pile while the structure is on its side.

After the piles are driven, air is now bled from the tank, if it is not full of water, and from the caisson 2, and the structure settles gently as the air is bled down. ii'he piles guide it as it settles vertically on bottom. If desired, especially if a suilicient number of legs are employed so that they are not all necessary for guide members for the piles, I may, by suitably arranging the piles, employ certain of the legs distributed about the periphery of the shoe 9' as jet pipes to jet Water or air to assist in the setting of the structure.

When the seat bottom is not flat or is muddy, I may, because of the peculiar design of my structure, which is particularly designed to permit of this function. excavate from underneath the structure.

This is accomplished by removing the bonnet i4. By applying a wrench to the head 3i, I may rotate the pipe 29 and the wheel 28. The hand wheel rides up the stud (loosening the clamp on the valve disc 23) until it rides up against the collar 26. A further quarter rotation moves the spider from underneath the brackets ll. It will be observed that the spider arms 2.! cannot be entered underneath the bracket 11 by the further rotation of the hand wheel because 01" the ridges IS. In this position the spider i is loosened and the spider l5, pipe 29, and the valve closure 23 and spider it! may be withdrawn from caisson 2.

An excavating tool, as, for example, a clam shell or orange peel bucket, may then be lowered through the caisson from a suitably anchored derrick barge. The piles will hold the structure in position against lateral displacement.

The bucket excavates underneath the bottom aided by the sluicing effect of the sea. When sufiicient excavation has occurred to form the desired bottom to act as a foundation for the structure, ,I may remove the excavating -cquip- This dimension is given.

ment. It will be observed that as I excavate the structure will settle vertically on the piles and the cutting edge of the shoe 9' will cut into the earth. I remove the excavating bucket and introduce concrete into the caisson 2 so that it discharges from the end of the caisson and fills, in underneath the conical bottom I. If the sea bottom is sloping or if there is any unevenness, concrete may discharge underneath the edge 9 to create a concrete cone on the bottom on which the structure rests.

It will be observed that the caisson is made of suiiicient size for this purpose. In order to indicate the order of magnitude of the caisson and to illustrate, it will pass conventional grab bucket equipment used for excavation. I may mention that for the structure illustrated, I may use a caisson 8 feet in diameter, more or less. not by way of limita tion but to illustrate the order of magnitude of the structure and its multiple functions.

In order to increase the stability of the structure I may unwater the tank by means of compressed air blown through lines 42 and by opening valves 39, and then closing the valve. Mud or heavy weighting fluid may then be introduced through certain of the lines 42 into the bottom tank, valves 33 being closed, and other of the lines 42 acting as air vents. The stability may also be increased by reintroducing the spider I5, pipe 25, and the cover plate 23, and spider 20, and locking spider 20 and clamping the cover plate against the plate i 6 by rotating the head 3| so as to rotate the spider underneath the brackets il beside the ridge i8 and against the ridge 5 9, and clamping the plate by further rotation of the wheel. Weighting mud may then be run into the central caisson.

It is not my purpose, especially, as will be described below, when it is desired that the structure is to be made removable, to cause the cement to rise any material distance up the caisson 2. However, some cement tends to rise up the conduit iii. If desired, therefore, the surface conductor casing i of the oil wells to be drilled from the structure, may be first set in the conduit it), held vertically and driven into the earth, and the concrete poured via 2, thus rising in It and around the surface to hold the casing for use in drilling.

It will be observed that the cement cone acts with the piles and the cemented surface conductor pipe to act as a stabilizer.

If the structure is to be removed, for example, when it is used for oil well drilling and no oil field is found, or if it becomes exhausted and it is desired to move'the structure away, this may be done relatively simply. The equipment on the deck and superstructure formed of the bracings 5i, 5 and deck supporting the deck are removed. A bottom anchor or a derrick barge is used to steady or remove the structure after it is released in a manner similar to that employed in erecting the same. If no cement is in the caisson 2 above the ring iii, the valve member may be placed in position by introducing the spider pipe '2 9, and disk 23 and. clamping spider 26. The rotation of the pipe 29 clockwise will enter the clamping spider underneath the brackets 5?, as described above, and continued rotation of the pipe 25 will clamp the disk 23' against the ring iii. A conventional inside cutter is run in the surface conductor pipes s and they are cut off at or near the mud line. The tubular piles ii; are cut oil at themud line by dropping a charge of powder .on

an electrical line to the bottom of the piles at the mud line, electrically firing the charge. This will cut off the piles beyond the end of the legs I. The released conductor pipes and the piles may then be removed. The mud, if any in the tank, may be discharged in many ways, as, for example, by introducing compressed air through lines 42 and discharging the mud through valves 38. When the mud is discharged the valves are closed.

The water may be discharged from the caisson 2 by replacing the bonnet l4 and introducing air under pressure via valve 44, water discharging via valve 33. When air breaks through, valve 33 is closed. As the water and mud are discharged from

valves

39 and 33, and the buoyancy of the structure increases, a point will be reached when the structure starts to float. If the adhesion of the structure against the mud and the cement hinders the release of the structure, a water or air line may be connected to the top of the legs 1, as by welding on the fluid line, and air or water jetted underneath the conical bottom and the shoe 9 to break the adhesion of the mud or earth against the surfaces of the structure and assist in the removal of the structure.

If it is desired to make the structure perma nent, the tank may be filled with cement via the line 32, and, if desired, also the caisson 2 may be filled with cement or with reinforcing members anchored to the earth when forming the cone bottom.

While I have described as a preferred embodiment a structure with a central caisson having top and bottom closures, I may omit the bottom closure and employ auxiliary flotation tank positioned at the top of the structure. In such construction I sacrifice the advantage of employing the caisson as a flotation tank, but do preserve the other advantages of this structure. For this reason, I believe the structure described in the application in which a bottom closure for the central caisson is employed, is a preferred structure.

While I have described a particular embodiment of my invention for the purpose of illustration, it should be understood that various modifications and adaptations thereof may be made within the spirit of the invention as set forth in the appended claims.

I claim:

1. A portable submarine structure, which comprises a plurality of tubular members having their interiors unobstructed and their walls imperforate, an elongated vertically disposed caisson, the exterior wall of said caisson and the exterior wall of said tubular members being connected, a removable closure for both ends of said caisson, means for flooding said caisson with water, between said closures, to control the buoyancy thereof, a buoyancy tank disposed at the lower end of said caisson, and means for independently flooding said buoyancy tank to control the buoyancy of the tank independently of said caisson.

2. A portable submarine structure adapted to support a drilling platform at an elevation above the water line, which comprises a plurality of vertical tubular members having their interiors unobstructed and their walls imperiorate, an elongated vertically disposed tubular caisson, said caisson having imperforate side walls connected to said members, a removable closure for both ends of said caisson, means for flooding said caisson with water to control the buoyancy thereof, a buoyancy tank disposed at the lower end of tending from the upper 8 I said caisson, means for flooding said buoyancy tank with water to control the buoyancy thereof, and a flared conical bottom to said tank, said conical bottom communicating with the caisson below the said closure.

3. A portable submarine structure adapted to support a drilling platform at an elevation above the water line, which comprises a plurality of unitary vertical imperforate tubular members open throughout their length, an elongated vertically disposed caisson having an imperforate and tubular wall and open at each end and connected to said members, a removable closure for both ends of said caisson, means for flooding said caisson with water to control the buoyancy thereof, an annular buoyancy tank, said caisson being centrally disposed of said tank in the central opening thereof, and conduits passing through the top and bottom of said tank.

4. A portable submarine structure adapted to support a. drilling platform at an elevation above the water line, which comprises a plurality of vertical tubular members, the walls of which are imperforate and continuous from approximately the bottom to the top of the structure, an elongated vertically disposed caisson connected to said members, a removable closure for both ends of said caisson, means for flooding said caisson with water to control the buoyancy thereof, an annular buoyancy tank, said caisson being centrally disposed of said tank in the central opening thereof, a conical bottom for said tank, said conical bot tom forming a flared mouth for said tank, a conduit passing through the to and bottom of said tank, a ring mounted near the lower end of said caisson, a disk mounted on said ring to close the end thereof, a clamping member for holding said disk tightly on said ring, and a member connected to said clamping member and extending longitudinally of said caisson and actuable from the upper end thereof for manipulating said clamping members.

5. A portable submarine structure adapted to support a drilling platform at an elevation above the water line, which comprises a plurality of vertical tubular members open throughout and continuous for their full length and the walls of said tubular members being imperforate, a vertical caisson having an imperforate tubular side wall, removable closures for the top and bottom openings of said caisson, means for flooding said caisson between the said closures to control the buoyancy of said caisson, said caisson being centrally disposed of said vertical members and exto the lower part of said structure, a tank positioned at the lower end of said members, a flared mouth for said central caisson at the lower end thereof, and means for flooding said caisson and said tank with water.

6. A portable submarine structure adapted to support a drilling platform at an elevation above the water line, which comprises a plurality of vertical members open throughout their length and having imperforate walls throughout their length, a. vertical caisson centrally disposed of said vertical members and having an imperforate wall throughout the length thereof and extending to a flared mouth for said central caisson at the lower end thereof, and a tank positioned at the lower end of said members, said flared mouth forming the bottom of said tank.

7. A portable submarine structure adapted to support a drilling platform at an elevation above the water line, which comprises a plurality of vertical members, a vertical caisson centrally disposed of said vertical members and extending from the upper to the-lower part of said structure, said vertical members and said caisson having imperforate walls, said vertical members and said vertical caisson being joined together by structural members attached to their outer walls, a removable closure for the upper endof said caisson, means for flooding the caisson below said closure, means for unwatering said caisson below said closure to control the buoyancy of said caisson, a tank positioned at the lower end of said members, means to floor said tankwith water, means to empty said. tank of said flooding water, and a flared mouth for said central caisson at the lower end thereof, said flared mouth and the lower part of said caisson formingapluraiity of the walls of said tank.

8. A buoyant submarine drilling platform structure adapted for erection on a submarine bottom, to ,supporta drilling platform above water, which comprises a plurality of vertical members, a deck structure connected to one end of said members, an elongated caisson extending along and adjacent to said vertical members, the lower end of said caisson being adjacent the lower end of said vertical members, cross-bracing between said members and said caisson, an auxiliary flotation tank positioned adjacent the lower end of said caisson, and bracing connection between said tank and said vertical members.

9. A buoyant submarine drilling platform structure adapted for erection on a submarine bottom to support a drilling platform above water, which comprises a plurality of vertical members, a deck structure connected to one end of said members, an elongated caisson extending along and adjacent to said vertical members, the lower end of said caisson being adjacent the lower end of said vertical members, cross-bracing between said members and said caisson, an auxiliary flotation tank positioned adjacent the lower end of said caisson, bracing connection between said tank and said vertical members, and a removable closure for said caisson positioned near one end of said caisson.

10. A buoyant submarine drilling platform structure adapted for erection on a submarine bottom, comprising a plurality of elongated leg members, a deck structure connected to one end of said leg members, an elongated caisson extending along and adjacent said elongated leg members, the lower end of said caisson being adjacent the lower end of said leg members, a removable closure at one end of said caisson, a removable closure at the other end of said caisson, and an inlet pipe connection and an outlet pipe connection connected to said caisson between said closures.

11. A buoyant submarine drilling platform structure adapted for erection on a submarine bot-tom, comprising a plurality of elongated leg members, a deck structure connected to one end of said members, an elongated caisson extending along and adjacent said members, the lower end of said caisson being adjacent the lower end of said members, a removable closure at one end of said caisson, a removable closure at the other end of said caisson, an inlet pipe connection and an outlet pipe connection connected to said caisson between said closures, a flotation tank positioned adjacent the ends of said caisson and elongated members, and an inlet pipe connection and outlet pipe connection connected to said tank.

12. A buoyant submarine drilling platform structure, comprising a plurality of elongated vertical-members, adeck structure connected-to one end'ofsaidmembers, an elongated caisson extending adjacent to and along said vertical members, a flared'mouth at one end of said caisson andextending beyond the ends of said vertical members, and cross-bracing between said vertical members and said caisson.

13. A buoyant submarine drilling platform structure, comprising a plurality of elongated vertical members, a deck structure connected to one end-of. said'membe-rs, an elongated'caisson extending adjacent to and along said vertical members, a flared mouth at one end of said caisson and-extending beyond the ends of saidverticalmembers, cross-bracing between said verticalmem-bers and said caisson, and a removable closure for said'caisson positioned near one end of said caisson andabove said flared mouth.

14. A- buoyant submarine drilling platform structure, comprising a plurality of elongated vertical members, a deck structure connected to one end of said members, an elongated caisson extending adjacent and along said vertical members, a flared mouth at one end of said caisson and extending beyond the ends of said vertical members, cross-bracing between said vertical iembers and said caisson, a removable closure for said caisson positioned near one end of said caisson and above said flared mouth, a removable closure at the other end of said caisson, and an inlet and an outlet connection to the caisson between said closures.

15. A submarine drilling platform erected on a submarine bottom, comprising a plurality of elongated vertical members extending above the water, a drilling platform positioned on said members above the water line, a caisson extending adjacent to and along said members, cross connections between said members and said caisson, a flared mouth at one end of said caisson, said flared mouth positioned on said submarine bottom, concrete positioned in said flared mouth and on said submarine bottom, and piles driven through said elongated vertical members and into the submarine bottom.

16. A submarine drilling platform erected on a submarine bottom, comprising a plurality of elongated tubular Vertical members extending above the water, a drilling platform positioned on said members above the water line, a caisson extending adjacent to and along said members, one end of said caisson positioned on said submarine bottom, cross connections between said members and said caisson, concrete positioned in said end and on said submarine bottom, and piles driven through said elongated vertical tubular members and into the submarine bottom.

17. A buoyant submarine structure adapted to support a drilling platform at an elevation above the water line, which comprises a plurality of vertical tubular members, an elongated vertically disposed caisson connected to said members, removable closure for both ends of said caisson, an inlet and outlet connection for flooding said caisson between said closures, with water to control the buoyancy thereof, and a flared conical mouth connected to said caisson below said closure.

18. A buoyant submarine structure adapted to support a drilling platform at an elevation above the water line, which comprises a plurality of vertical members, a deck structure connected to one end of said members, a vertical caisson centrally disposedof said vertical members and extending from the upper to the lower part of said structure, said vertical members and said vertical caisson having imperforate walls, a removable closure for the upper end of said caisson, means for flooding the caisson below said closure, means for unwatering said caisson below said closure to control the buoyancy of said caisson, and a flared mouth at the lower end of said central caisson.

19. A buoyant submarine structure adapted to support a drilling platform at an elevation above the water line, which comprises a plurality of vertical tubular members, a vertical caisson centrally disposed of said vertical members and extending from the upper to the lower part of said structure, said tubular members having imperforate walls and being unobstructed throughout their length, a removable closure for the upper end of said caisson, means for flooding the caisson below said closure, means for unwatering said caisson below said closure to control the buoyancy of said caisson, a

tank positioned at the lower end of said members, and a flared mouth for said central caisson at the lower end thereof.

5 References Cited in the file or this patent UNITED STATES PATENTS Number Name Date Plummer Sept. 5, 1939 Voorhees Jan. 23, 1940 Kirby June 10, 1947 Shannon Dec. 19, 1950 Guenzel Jan. 1, 1952 Parks Apr. 1, 1952 FOREIGN PATENTS Country Date France of 1875 Italy of 1927 OTHER REFERENCES Eng. News-Record, page 842, June 13, 1935.