US2236682A - Marine foundation and method of construction - Google Patents

Description

H. E. GROSS April 1, 1941.

CONSTRUCTION Original Filed Dec. 31, 1937 6 Sheets-Sheet 1 Hal 0m: @055 N NT Ii \L.

I VE OR IATTQRNEY I April 1941- H. E. GROSS 2.236.682

IARII lE FOUNDATION AND METHOD OF CONSTRUCTION Original Filbd Deq.- 31, 1937 6 She sts-Sheet 2 f/E/VQVZ 6 9055 INVENTOR ATTORN EY April 1, 1941. H. E. GROSS MARINE FOUNDATION AND METHOD OF CONSTRUCTION 31, 1937 6 Sheets-Sheet 3 Original Filed Dec.

flf/MQVE 6905.5 INVENTOR ATTORN EY \w an Ap 1941- H. E. GROSS 36,682

amiss rouummou m urn-non or consnwcnou Original Filed Dec. 31, 1937 6 Sheets-Sheet 4 HE/VQVE 6m;

INVENTOR A'I I'ORNEY April 1, 1941. GROSS 2,236,682

MARINE FOUNDATION AND METHOD OF CONSTRUCTION Original Filed Dec. 31, 1937 6 Sheets-Sheet 5 INVENTOR ATTORN EY April 1, 1941. H. E GROSS IARINE FOUNDATI ON AND IETHOD 01'' CONSTRUCTION Original Filed Dec. 31, 1937 6 Sheets-Sheet 5 flf/VQV Z: 6;?055

INVENT My 7 ATTOR Patented Apr. 1, 1941 UNITED. STATES PATENT A OFFICE I azsacsz I mama rooms-non AND mz'rnon or consrauc'non Henry Emmett Gross, College Station, Tex ass'ignor to Standard Oil Development Company, a corporation of Delaware Application 19 Claims.

My invention relates to improvements in marine foundations and in their construction.

Great difliculty has always been encountered in building marine foundations in any great depth of water, and the cost of constructing such foundations under present methods of construction is almost prohibitive. The driving of piles in from 500 to 1000 feet of wateris out of the question, and the sinking of caissons in such depths is well nigh impossible, as well as economically prohibitive. Submersible barges have not proven successful at such depths. As a result there are no man made mid-ocean airplane landing docks, we have been unable to core drill the English Channel to determine the feasibility of a tunnel from England to France, and we have not, as yet, been able to drill for oil economically in more than approximately 65 feet of water.

The chief object of my invention therefore, is to provide a marine foundation construction which will not only allow any hydraulic engineer to build such a foundation and locate it in 1000 or more feet of water, but which can be constructed in such depths of water at a cost approximating the present shallow water foundations built under present methods ofconstruction.

Other objects of the invention are, to provide a marine foundation construction which eliminates the use of piles or caissons; which will as- December 31, 1937, Serial No. 182,829

Renewed July 1, 1939 panying drawings, which are chosen for illustrative purposes only, and in which Figure'l is a side elevation of a foundation made in accordance with this invention, and illustrates particularly its use as a foundation for oil well derricks and complete drilling equipment;

Figure 2 is a side sectional view of aportion of the foundation and illustrates particularly a means of rigidly anchoring the foundation on the marine floor;

Figure 3 is a side elevation of the lower portion of the foundation, and illustrates a preferred weight method of firmly positioning the base of the foundation on the marine floor in accordance with the invention;

Figures 4 and 5 are sectional side and end elevations respectively of similar portions of the device illustrating construction details, as well as details of the preferred weight anchoring method;

Figure 6 is a plan view of a portion of the base of the foundation illustrating construction details, and further details of the weightanchorsure maximum strength and stability combined with minimum weight on the ocean floor, thereby sired and placed in position on a submerged mountain top; which may be constructed on land, towed to position, sunk and anchored in great depths of water; which is substantially unaffected by the tide, wind or wave action due to its skeleton formation, its natural inertia, its use of buoyancy to maintain its vertical position, and its extremely rigid construction; and which may be used in the building of bridges, lighthouses, piers and mid-ocean airplane landing fields, as a foundation for geophysical instruments, as well as for oil well drilling where the well location is in deep water.

For simplicity, the invention will be described in detail in its adaptation to oil well drilling foundations located in 500 feet or more of water.

The details in construction of a preferred form of my invention, together with other objects, will be better understood from the following description whenread in connection with the accomstruction of the enlarged base;

ing method;

Figures '1 and 8 are side and plan views re- Figures 9 and 10 are fragmentary plan and side elevations respectively of similar portions of the foundation, illustrating details of one preferred method of bracing the foundation;

Figures 11 and 12 are plan views of one end of a solid brace rod, Figure 12 illustrating the way in which the end of the rod is treated preparatory to securing it to one of the other structural members, and Figure 11 illustrating the actual fasten- In general, the structure, as built for oil welldrilling, consists of a derrick-like foundation 5 made up of buoyant hollow casing uprights surrounding ahollow central conductor pipe, all rigidly spaced apart by hollow buoyant cross braces. All cross bracing members may either be hollow and buoyant, as in Fig. 15, or some may be solid according to the details of construction shown in Figs. 9 and 10, and hereinafter explained. The uprights may be vertical and parallel or they may taper inwardly from the bottom upward to form a substantially frusto-pyramidal skeleton structure, as illustrated. In either case, the lower ends of the uprights are spaced apart sufllciently to give the entire structure a large bottom area, which area will be governed by the height to which the finished structure is to be built. It will be understood throughout this description that the central conductor pipe 39 will be included in the structure only when it is to be used as a well drilling foundation. When used for other purposes the conductor pipe is not an essential feature of the foundation, and may be eliminated. Hollow buoyant structural members are used not only to facilitate the section by section construction of the foundation in the water, but to serve as a very positive and forceful means of maintaining the foundation in a vertical position in great depths of water. An experiment which clearly illustrates this use of buoyancy is the holding of one end of a light stick of wood under the surface of water and barely permitting the other end of the stick to protrude from the water. The stick will assume and maintain a vertical position in the water, and in comparison to the actual weight of the stick in the atmosphere, a large force must be applied to the protruding end to move it out of vertical position.

Referring to the drawings, (Figs, 9 and 15),

the hollow upright members 20, 2|, 22, and 23 are formed preferably of numerous sections of thick walled hollow casing, the adjacent ends of the sections being rigidly fastened together by means of the usual pipe joints 24 (Fig. 1) the joints being welded to lend additional rigidity, as well as to assure a water tight joint. The end of the lowermost sections are made water tight by inserting and Welding a metal plate 25 therein, as shown in Fig. 2. The horizontal compression members 26 are also made preferably of substantially the same type hollow casing, the outer ends of which are made water tight by the welded insert plate method, mentioned above. The ends of each of the members 26 are pre-cut to fit precisely, a template being used for the purpose. (The various joints are illustrated in Figs. 4, 9, and 10.) The shaped ends are then fitted into position against the upright members, and are welded thereto, the joint again being made water tight. As to the diagonal horizontal brace members 21 and 21A (Figs. 9, 10 and 15), and the diagonal upright sway braces 28 and 28A (Figs. 1 to 4, 9 and 10), they may be made either of hollow casing or of solid rods. If these braces are hollow as designated by the numerals 2'1 and 28, the ends are made water tight as above, and secured in position by welded template joints. If formed of solid rods, as designated by the numerals 21A and 28A they are of considerably smaller diameter (as shown in Figs. 9 and 10), and the ends of the rods are split longitudinally, heated and bent into shape around the tubular members, after which they are firmly welded in position, (See Figs. 11 and 12.) The relative advantages of the solid and the hollow diagonal brace members 21, 21A, 28, and 28A will be hereinafter discussed with relation to the buoyan y desired and the particular conditions under which the foundation is being constructed. When solid members are used it is contemplated they will preferably be formed of one continuous piece of rod between tubular members.

The details of construction thus far described are not in themselves unusual, save for the water tight joints and the sealing of the ends of the various sections of easing used. The inventive idea, however, not only includes the construction of a marine foundation, but also a method of construction which will enable one skilled in the art to build such a foundation in 500 to 1000 feet of water. Figs. 13 and 14 particularly illustrate the preliminary steps in the method of building the foundation.

It is contemplated, of course, that the ultimate location of the foundation will have first been determined, and that the exact depth of the water at that point also will have been determined. The latter is necessary in order to determine the approximate size of the base needed to properly support a foundation of the required height. The condition of the marine fioor, whether firm or soft, as well as the wave action at the particular location must also be taken into consideration in determining the size of the base. The condition of the marine floor will also determine somewhat the width of the skids 29, 30,31, 32,33, and 34 (Figs. 8 and 15).

When the desired size for the base has been determined, construction of the skids is begun. The skids are preferably formed of what is commonly known in the oil industry as junk casing," but the walls of the individual sections should be water tight. I prefer to use this junk casing to cut the cost'of construction, although any new or used casing may be used for the purpose. All the joints are preferably screw and weld joints as previously described, and the ends of the individual members 35 are preferably plugged with a metal plate 25 and welded water tight, as previously described, and as illustrated in Fig. 2. As shown in Figs. 5 and 6, a number of these casing members 35 are laid side by side, and heavy boiler plate 36 is spot welded, as indicated by the numerals 31, to the assembled casing members. The boiler plate is first perforated at proper intervals, and the weld is made through the perforations directly to the outer wall of each casing member. (Fig. 4.) This makes a very rigid connection and holds the various casing members rigidly side by side, yet permits these casing members to remain water tight. The boiler plate serves as the bottom of the skid. The various casing mem bers 35 are bent upward at their opposite ends, and the boiler plate is bent to conform. The ends of the casing members 35 are cut at different points to form a substantially arcuate prow for the skid, as shown in Figs. 5, 6, 15, and 16, and the boiler plate is out along the ends of the casing members, as illustrated. A piece of boiler plate 52 (Figs. 4 and 6) is then similarly welded to the opposite surface of some of the members 35 near each end of each skid. These plates 52 serve as bases for the uprights 20, 2|, 22, and 23, the uprights as well as the adjacent ends of the lowermost members 26 being welded firmly to the plates 52, thus anchoring the skids rigidly to the rest of the structure. The width of the'skids may be varied to suit conditions.

After the skids have been completed, the first section of the foundation is built thereon, as previously described, and as illustrated in Fig. 13. The first section will probably be about 40 feet in height, if Range 3 standard length casing sections'are used for uprights. It will include the diagonal sway braces 28 or 28A and the horizon tal compression members 25. The construction of the skids and the entire first section may be completed on the ocean beach, (Fig. 13) in proximity to the water line, and when completed, the entire structure is moved into the water This may be done at high tide by dragging it across the beach on its skids, tugs being the motive power; or, at low tide, double railroad tracks may be laid, one for each skid, the entire structure may be placed on railroad car trucks and rolled to the waters edge, where it may be easily launched at high tide, and the tracks and trucks reclaimed.

ed is offset, and it is comparatively easy to move the foundation from point to point in the water toward its ultimate location as each section is added. I prefer to build the foundation of casing members which will contribute positive buoyancy to it during construction. For this reason I prefer to construct the skids 29, 30, 3|, 32, 33 and 34, the compression members 26, the sway braces 28, and the uprights 2|, 22, 23, and 24 all of 18 O. D. 96 #/ft. casing which has a net positive buoyancy of 25 per foot. Such a positive buoyancy would morethan offset the weight of solid 2" diagonal horizontal braces 21A, and of solid-2" diagonal hangers 38 (Fig. 10) for supporting the conductor pipe 39, together with the weight of an open ended conductor pipe,

- although a closed ended buoyant conductor pipe may be used if desired. The foundation, then, regardless of the stage of construction, would be comparatively easy to move by tug power. If hollow cross bracing is used throughout, then a standard casing may be chosen which has approximately 12# buoyancy per foot.

After the first section has been completed and launched it will be towed by tug power toward its 16, the lower end of this pipe being spaced somewhat above the skids. It is contemplated that solid hangers 38 will be used even'though all cross bracing and sway bracing is made of hollow casing. Any other practical means, however, may be used for supporting the weight of this conductor pipe. When the second section has been completed, the structure is again pulled by tug toward its ultimate location until only 10 or 15 feet of it protrudes from the water. Let it be said here that it is not contemplated that the structure can be towed to each successive new location at a speed of 5 knots or even 1 knot. It may require 24 hours or even '72 hours to move it from one location to another, but even so, the man hour cost of construction will be comparatively very low. By moving it slowly, the resistance of the water is negligible, and with the inherent buoyancy of the structure offsetting the weight of the structural members and tending to keep the structure upright in'the water, the moving operation is comparatively easy.

Section afterv section is constructed in this manner, a halter-like tow line being used after the structure has grown in height. To prevent any possibility of the buoyancy of the lower end of the structure tending to topple it over in the water, the lower end of the foundation may be weighted, by such means as is illustrated in Figs.

3 to 6, although otherweighting means may be' employed. Any means used, however, I should insure the placing of the weight atthe place lengths 4| and 42 of the same size I-beam are ultimate location until the 'water increases in depth to about 30 feet, leaving some 10 feet of the first section out of the water.

water will be sufficient to offset the buoyancy of the submerged members and to keep the first section and its skids setting firmly on the marine floor. If a casing of comparatively high buoyancy is used, the section may be weighted as required by any suitable method to keep it on the i the construction may proceed with dispatch. With the exception of the first section, all sections may be constructed from a floating barge which carries its own hoisting machinery. together with suflicient supplies to build several complete sections.

After the uprights and cross braces of the second section have been secured in position, the

The weight of the casing members above the surface of the.

then placed, one on each side of the central beam 7 40, as shown, and welded into position, their tops forming a weight supporting platform. A total of four or more of these platforms are built, as shown in Fig. 15. As shown in Figs. 4 and 5, the lowermost compression members 26 pass through suitably sized andproperly located holes in the I-beams 40, 4| and 42, and may be welded to the adjacent portion thereof, if desired. To the platform formed by the tops of these I-beams, is welded the lower end of a string of casing 43, and this string of casing is built up, section by section, as the rest of the structure increases in height. Surrounding the string 43 is a second string of casing 44 which is also built up section by section, with the rest of the foundation.

The string 44 is preferably formed of flush joint casing sections, and a heavy outstanding flange 45 is firmly welded about its lower end. The upper ends of these two strings of casing 43 and 44 are held in position by means of slips 46 and split spiders 41 (Fig. 4), temporarily supported on timber false work 48, all of which may be moved upward from cross brace to cross brace, as the foundation increases in height, section by section. The bottom surface of the flange 45 rests freely on the I-beam platform, while its upper surface is adapted to receive weights, such as railroad car'wheels 49. It will be remembered first two sections of the conductor pipe 39 are secured in position, as shown in Figs. 14, 15, and

that the lower end of the inner string 43 only is welded to the I-beams, and that the outer string 44 is entirely free to move longitudinally with respect to the inner string. The joints of the outer string, being flush, present no obstruction to the downward progress of railroad car wheels or other similar weights dropped over the upper end of the string. I prefer to use junk railroad car wheels for weights because of their compact form. They weigh from 750# to 900#, only vary in diameter from 33" to 36", and can be obtained with 8", 9", or 10 hub diameters. With such a method of weighting, the weights may be added as needed, and may also be recovered simply by pulling up the outer string of casing 44 and reclaiming the various casing sections as they emerge. The flange 45, being of larger diameter than .the holes in the weights, prevents the weights from slipping off the lower end of the string 44, and the string 43 acts as a guide to prevent injury to the cross bracing or sway bracing as the weights are lifted through the interior of the structure. Necessarily, the first section of these two strings of casing 43 and 44, must be placed in position and their upper ends temporarily supported as described, before the first section of the foundation is launched. With this method of weighting it will be easily seen that more buoyant casing sections than previously mentioned can be used for all structural members, and that the buoyancy can thus be utilized to keep the entire structure vertical in the water under any and all conditions on or near the surface of the water, regardless of the stage of con struction.

After the foundation has been towed to its ultimate location, and the last section has been erected (the upper end of which should in most cases be from 40 to 50 feet above sea level), an alternative method of anchoring may be-used if desired, in place of the weights. Fig. 2 illustrates this alternative method, which will ordinarily be used only when the foundation is to be permanently located. To properly anchor the foundation according to this method, a suitable platform is constructed (bridge truss construction approximately 10 feet deep) and a rotary drilling rig is positioned on the platform. The

rig is positioned over each of the uprights 20, 2|,

22 and 23 in turn, and the drill stem lowered through these uprights. The respective plates in the lower end of each upright are drilled through and penetration into the ocean floor is continued to a desired depth, say 500 feet. Casing Si is then set in each hole through the upright members of the foundation, or if preferred the drill pipe may be left in the hole for this purpose. Cement is then introduced, and the inner casing ii is cemented in the manner common to oil well drilling practice, the cement rising about the outside of the casing, as well as into the upright leg members. (See Fig. 2.) With a casing 5| thus cemented in each of the upright members of the foundation a very firm anchorage is provided and, if desired, the strings of casing 43 and 44 together with the weights 49 ,may then be removed, as previously described. To prevent any possibility of relative longitudinal movement between the leg members and their respective inner casings 5|, a casing head 53 may be attached to the upper end of each leg member and to the upper end of its respective inner casing 5|.

Still another alternative method of maintaining the foundation in upright position against wind and wave action is illustrated in Figs. 7 and 8. In these figures is illustrated an enlarged octagon shaped base, there being two longer skids I0 and 3| substituted for the shorter skids 33 and 34, and two skids I! and 32 added at the side edges. The skids are formed in substantially the same manner, and the central upright portion is made substantially the same as the base of the foundation illustrated in Figs. 1, 3 and 13 to 16 inclusive. For purposes of clarity, only the main structural members have been shown in these two figures, the cross bracing and sway bracing being omitted. It is contemplated, however, that suitable bracing will be used, that the casing sections used will be water tight, and thatthe various joints will be fitted and welded, as previously described. This type of base gives approximately six times the base area and fully three times the stability, completely ignoring the buoyancy factor in both constructions.

It is believed that the inventive idea has been fully disclosed by the above description, and that said description would enable those familiar with the art to practice the invention. Figures 9 to 12 simply illustrate the use of solid sway braces 25A, and solid diagonal horizontal members "A, as opposed to the use of hollow brace members 21 and 28 as shown in the other figures.

I point out that a foundation constructed in accordance with my invention will have a high degree of stability. The features which contribute stability are: the large base firmly anchored in a horizontal plane (by either or both of the two methods disclosed) with the rigid upright skeleton structure rigidly secured thereto; the inherent buoyancy of the structure, which tends to keep it in vertical position; the natural inertia of the structure due to its own weight in the atmosphere; and the resistance of the water surrounding the submerged structural members against movement of the members in any direction. To move the foundation away from vertical position, then, the force would have to be suflicient to overcome all these factors combined.

Any wind, water, or wave action would necessarily be applied to that portion of the foundation which protrudes from the surface of the water, or to that portion immediately adjacent the water level. Due to its skeleton construction, the protruding portion presents comparatively little resistance to such forces. Considering this small surface resistance together with the. four above mentioned stability features, it

' will be easily understood that the completed structure will have as high a degree of stability in deep water as the larger, more bulky foundations now in use have in shallow water.

While I have described and illustrated specific embodiments of my invention I am aware that numerous alterations and changes may be made therein and I do not wish to be limited except by the prior art and by the scope of the appended claims.

I claim:

1. An elongated marine foundation comprising a plurality of rigid individually water buoyant structural sections of skeleton formation superimposed one upon the other and rigidly secured together; and a plurality of substantially flat bottomed skids rigidly secured to the lowermost section and adapted to facilitate the moving of the skeleton structure across the ocean floor at any stage of its construction, and also adapted to serve as a base for the structure.

2. An elongated marine foundation comprising a plurality of rigid water buoyant structural sections of skeleton formation superimposed one upon the other and rigidly secured together; a plurality of substantially fiat bottomed skids rigidly secured to the lowermost section' and adapted to facilitate the moving of the skeleton structure from place to place on the ocean floor at any stage of construction as well as to serve as a base for the structure; and means extending from the top of the uppermost section to said skids for guiding weights to a predetermined resting place on said skids.

3. A marine foundation comprising: a plurality of spaced sealed air filled hollow water buoyant upright leg members; intersecting spaced sealed air filled hollow water buoyant cross brace members rigidly secured at intervals to said leg members; diagonally disposed horizontal and upright sealed hollow water buoyant bracing tension members likewise rigidly secured to said leg members and to each other where they intersect, all of said members together forming a rigid buoyant elongated skeleton structure; spaced weights positioned on the base of said structure; and means for guiding said weights from the top of said structure to predetermined locations on its base, whereby all the buoyancy of the elongated structure which is above said weights and is submerged plurality otjspaced sealed air filled hollow water buoyant cross brace members rigidly secured at intervals to said leg members; diagonally disposed horizontal members and diagonally disposed upright members rigidly secured to said leg Y members, to said cross brace members, andto brace members, their opposite ends rigidly sein a liquid is utilized to maintain said structure in vertical position in the liquid.

4. A marine foundation comprising a multiplicity of' water buoyant structural members including spaced upright leg members, compression brace members, and tension brace members all rigidly secured together in a manner to form a water buoyant rigid skeleton structure; weights for the base of said structure suflicient to permit its inherent buoyancy to maintain the structure in an upright position in water while permitting its upper end to protrude from the surface of the water; and means for guiding additional weights from the protruding end of said structure to its base for causing its base to seat solidly on the marine floor.

5. Organization as described in claim 4, and means extending from the inside of each of said leg members, out through the lower ends thereof and into the ocean fioor for firmly anchoring said foundation in permanent position.

6. A derrick-like marine foundation comprising a multiplicity of hollow sealed water buoyant structural members including spaced upright leg members, horizontal cross brace members having their opposite ends rigidly secured at intervals to said leg members, diagonal horizontal cross brace membershaving their opposite ends rigidly secured at intervals to opposed ones of said leg members and to each other where they intersect,

and diagonal upright compression brace members having their opposite ends rigidly secured to opposite ends of certain proximate onesbf said first mentioned horizontal cross brace members as well as to adjacent ones of said leg members, said aforementioned members together forming a water buoyant rigid skeleton structure; removable weights for the base of said structure sufficient to permit its inherent buoyancy to maintain the structure in upright position in water while permitting its upper end to protrude from the surface of the water; and means extending from its protruding upper endto the base of said structure for guiding said weights through the water to a particular point on said base, and for removing said weights as desired.

7. A marine foundation for oil well drilling comprising: a plurality of spaced sealed air filled water buoyant upright leg members; a greater cured to adjacent ones of said leg members at intervals; a plurality of diagonal horizontal cross brace members intersecting in pairs and each pair having their opposite ends rigidly secured to opposed ones of said leg members; diagonal upright sway brace members connected rigidly to adjacent ones of said leg members at intervals and disposed between opposite ends of certain ones of said first mentioned horizontal cross brace members and rigidly secured thereto; a plurality of substantially fiat bottomed skids each rigidly secured to the lowermost ends of a plurality of said leg members as well as to certain of the lowermost cross brace members and adapted to facilitate the moving of the entire foundation from point to point on the ocean fioor as well as to serve as a base for the foundation; and weight guiding means extending from the top of the structure to said skids for guiding weights to a predetermined resting place on said skids.

10. A marine foundation comprising: a plurality of spaced sealed air filledhollow upright leg members; and a greater plurality of spaced sealed air filled hollow cross brace members rigidly secured to adjacent ones of said leg members to form a completely rigid skeleton structure, said structure, as a unit, being substantially symmetrical and having a slightly negative buoyancy when submerged. in water.

11. -A marine foundation comprising: a plu-' rality of spaced sealed air filled hollow upright leg members; a plurality of structural cross brace members secured to adjacent ones of said leg members to form a completely rigid skeleton structure, the buoyancy of said leg members being sufiicient to substantially offset the weight of the entire structure making it only very slightly heavier than the water which it displaces when it is submerged in a body of water; and means for weighting the lowermost end of said structure at predetermined points after it is submerged in water.

12. The method of constructing a marine foundation which comprises building a buoyant first section on dry land; launching and towing said first section toward its ultimate location to a point at which the water is slightly less in depth than the height of said first section; building a buoyant second section on the upper protruding end of said first section; towing the partially completed buoyant structure farther toward its ultimate location to a point at which the water is slightly less in depth than the height of the two combined sections; weighting the base of the buoyant structure as needed to maintain it in an upright position in the water; repeating these steps until the foundation has reached its required height and until it has reached its ultimate location; and anchoring the base of the foundation firmly on the marine floor.

13. An elongated marine foundation comprising a plurality of rigid water buoyant, structural sections of skeleton formation, superimposed one upon the other and rigidly secured together, and

a substantially flat bottomed skid-like base secured to the lowermost section and adapted to facilitate the moving of the skeleton structure from place to place on the bed of, a body of water at any stage of construction, aswell as to serve as a base for the structure.

14. An elongated marine foundation comprising a-plurality of rigid water buoyant, structural sections of skeleton formation, superimposed one upon the other and rigidly secured together, a substantially flat bottomed base member rigidly secured to the lowermost section and adapted to facilitate the moging of the skeleton structure from place to place on the bed of a body of water at any stage of construction as well as to serve as s,ase',ess

ber when the latter is in the desired anchoring position and to be cemented in place in the earth.

17. A method for anchoring a marine foundation for oil well drilling comprising providing on said foundation a plurality of hollow leg members rigidly secured to said foundation, passing a drill stem-through each of said members and drilling into the earth below the foundation a substantial distance, inserting a tubing through each of said hollow leg members and into the boreholes so drilled and forcing cementing material into said boreholes and up around said tubing.

18. A method for anchoring a marine foundation for oil well drilling having a derrick structure provided with hollow leg members terminating adjacent the bottom of said foundation comprising inserting a drillstem in each of a plurality of said leg members and drilling into the earth boreholes in alignment with corresponding leg members, placing tubing in each of said leg members extending into its corresponding borehole and forcing cementing material into said boreholes and up around said tubing.

19. A marine foundation foroil well drilling comprising a plurality of spaced sealed gas filled, water-buoyant, upright leg members, a greater plurality of spaced, sealed, gas-filled, waterbu'oyant, cross-bar members rigidly secured to said leg members, all of said members together forming a rigid. buoyant, elongated structure, a conductor pipe centrally placed within said structure. and means for rigidly holding said conductor pipe in spaced relation to said leg members. HENRY EMMETI GROSS.

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