US2939290A

US2939290A - Marine drilling rig foundations

Info

Publication number: US2939290A
Application number: US459677A
Authority: US
Inventors: Wilfred S Crake
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1954-10-01
Filing date: 1954-10-01
Publication date: 1960-06-07
Anticipated expiration: 1977-06-07

Description

June 7, 1960 W. s. CRAKE MARINE DRILLING RIG FoUNDATloNs 3 Sheets-Sheet 1 Filed Oct. l, 1954 FIG.

FIG. 7

INVENTOR W.S. CRAKE BY f/.wmg

FIG. 6

HIS AGENT W. S. CRAKE MARINE DRILLING RIG FOUNDATIONS June 7, 1960 Filed Oct. l, 1954 3 Sheets-Sheet 2 D D M T m N J C E n n .G S. c A W 0 O O H H n U T A@ m n n v Y n m B C C M June 7, 1960 w. s. CRAKE 2,939,290

MARINE DRILLING RIG FOUNDATIONS Filed Oct. l, 1954 3 Sheets-Sheet 3 L9 Ll..

lo N

NVENTOR W. S. CRAKE Y HlS AGENT United States Patent O MARINE DRILLING RIG FOUNDATIONS Wilfred S. Crake, Houston, Tex., assignor to Shell Oil Company, a corporation of Delaware Filed Oct. 1, 1954, Ser. No. 459,677

1 Claim. (Cl. 6146.5)

`This invention relates to marine foundation structures for use in conjunction with a submersible barge for drilling oi shore oil and gas wells in offshore or inland waters, and pertains more specifically to a portable marine foundation which is particularly useful in moderately deep bodies of water, and which can be oated into position and removed after it has served its purpose so as to avoid the expense and delay ofproviding a piling structure to form a permanent foundation.

When drilling oil wells in submerged areas, serious problems are encountered in providing suitable foundations for use beneath conventional marine drilling barges in waters of a depth greater than that for which the drilling barge was designed. Submersible barges, which have been used with considerable success in relatively shallow land-locked water areas, are generally considered to be impractical when used in the greater depths and under the exposed conditions prevailing in offshore drilling. The restrictions on the use of semi-submerged drilling barges in deeper waters are mainly due to the fact that when the barge is sunk to the bottom, the deck or operating platform of the barge is either below the surface of the water or so close to the surface that drilling operations cannot be carried on safely. YThus, in drilling oil wells in submerged areas where the water is about feet or more deep, ordinary submersible drilling barges cannot be used and it is necessary to either build large expensive barges of special design, or to drive pilings on which a permanent offshore drilling platform may be constructed.

In many oshore locations, pads or submerged islands of oyster shells or other materials have been used, in order to spread the load of the drilling barge on poor loadbearing submerged soils, and/or to raise the bottom of the drilling location so that the submersible barge may be used in water deeper than that for which it was originally designed, thus extending the usefulness of the barge and its drilling rig positioned thereon. These islands have been raised as much as6 feet or more from the of the shells or other materials under water, excessively large quantities of shells must be used to` form an island having a top of suicient area for the barge to rest upon safely during drilling. v v

Since the problem of the actual drilling of an olfshore well requires heavier equipment and larger barges, and imposes heavy loads on the supporting mast or rig than does post-drilling work, it is necessary to build larger foundations or islands for drilling than for wellv repair and maintenance work, which is carried out with lighter equipment and can be accomplished in a much shorter time.

The -primary object of thisinvention is to provide a marine drilling rig foundation capable of carrying the load of a submersible drilling barge and comprising Va elsewhere.

2,939,290 Patented June 7, 1960'I icc `portion provides sufficient space for minor well repairsl and maintenance service.

A further object of the present invention is to provide a marine drilling rig foundation adapted to be used submersible barges and capable of acting as a break water for said barges.

Another object of this invention is to provide a marine drilling rig foundation for use with submersible drilling barges, a major portion of said foundation being adapted to be made buoyant and towed to another drilling location.

These and other objects of this invention will be understood from thefollowing description taken with reference to the drawing, wherein:

' Figure 1 is a diagrammatic view, partly in cross-section, of a conventional drilling barge positioned on a marine vdrilling rig foundation formed in accordance with the present invention.

Figures 2 and 3 are schematic plan views of alternate arrangements of the present marine foundation for drill ing barges.

Figure 4 is a view, partly in cross-section, of several sections of the oatable .barrier which forms that portion of the present marine drilling rig foundation which may be salvaged.

Figure 5 is an enlarged detailed view, partly in crosssection,.illustrating portions of two of the lloatable sections of the present oatable barrier, and the means by which they are hinged together.

Figure 6 is a schematic plan view illustrating a tug towing the hinged oatable barrier of the present invenwall and is lled with shell, sand, rock, or other suitable material 16 to serve as a base upon which the barge 11 can rest. The bottom soil level is indicated at 14, while l numeral 15 indicates the mean water level. y If the present barrier 13 were not employed to contain the shell 16, the normal angle of repose of the shells forming the island or foundation beneath the surface of the water would be substantially that of

dotted lines

17 and 18 which illustrate the sloping surface of the additional.

quantity of the shells which would be needed in `such case to form a foundation of the desired size. Furthermore, additional quantities of shells would have to be added to the foundation from time to time to replace shellsremoved by erosion or wave action during thel13 of the present invention comprises a plurality of hinged oatable sections sucient in number to surround the sub?` rrrrersible barge 11 beingrused. -Thus,the number of sec 'tions making up the barrier depends upon the size of the theV adjacent'floatable section of the barrier. Y

ymembers 26 and 27 of adjacent'sections 22 and 23 ofthe barrier may be held together by meansof a hinge pin 2 8 tions of the Vbarrier is Aa rigid, hollow,.viioatable. structure',

which maybe reinforced'by, internal:y bracingmembers 25as'- shown in Figure 5L The construction and lweighting offeach section of the barrier is suchthat these/ation may. be floated to a drilling location with the. major axis of each section positioned in a substantially vertical plane, as shown in Figures 4 and 5L One or more hinge members 26 are iixedly attached to each endV of each section 21 to 24 so as to interlock with hinge member 27 lixedlyV attached .to the -adjacentfendof The-hinge which extends therethrough. Alternatively, any two sections of the barrier, for

example sections

21 and 22, may have their hinged

members

26 and 27 secured together by means of a spud or small pile 31 which is driven through the hinge members 26 and 27V and down into the ocean oor 14Y (Figure 1) thus securely anchoring the, barrierA in position around the drillingsite.

VIn the event that spuds or piles '31 are employed to-` secure the hinged.

sections

26 and 27 of adjacent oatable sections of'a barrier together, each spud "31 is provided the

uppermost hinge member

26 or 27, a bolt can. be

slipped through the hole 32 to prevent the spud 31 fromk slipping down through the hinge members again.

' In ythe event that all sections 21'to 2'4 of the barrier are l to be connected together by means of hinge pins V28, several ,sections of the barrier, such for example as section 22 (Figure 4), should be provided with suitable spud- Vholding'means adapted to receive therein andv permit the passage therethrough a spudY or pile 34 which is driven into the ocean door to anchor the entire floatable barrier thereto. The Spud-holding means 33 may be eitherivsecured to the outside of a section 22 or may be positioned therein. In the event that the Spudholding means '33 is positioned vertically within the uidtight section 22, the Spud-holding means preferably rcomprises an elongated tubular member welded in a uidtight manner `at thetop.Y and bottom to the top and bottom of the section 22. The: internal diameter of the tubular Spud-holding -means 33,l

isslightly larger than the outside diameter ofthe spud to be positioned therein. At the same time, thel outside dif.V ameter of the 'tubular Spud-holding means 33 is less than the' internal width of the hollow oatable section 2in` order to allow the passage of air and water readily fromY 'one end of the section to the other.

vEach section of the barrier, for examplefoatab1e section 22, is provided with means for oodingthe section such as, for example, one or more ood valves 35,.whi'ch are in communication either directly or through` a short Y conduit member 36 (Figurev 5), with the space. outside the` section. YPreferably the ood valves 3S larepositioned within'the hollow chamber of each section 21 ('Figure 5) to protect them from being knocked ott when the barrier..

is'being moved from place to place.v However, it is, to be understood that theood valves 35 can be readily Vmcugulted'A on `the outsideof each chamber.` Preferably,-

each' oodlvalve )351s -provided with miv vextelrlsimr.Jumilla:

37 which extends upward through the topv of the section with the end of `the Vhandle being positioned in a recessed.

valve box 38 which protectsfthe valve handle from injury during operations.

Each section of the present barrier is also provided with valve means for introducing air into each' section in order to make a ooded section buoyant prior -to its removal to another location.'Y Each section is provided With at least one and preferablytwoair intake ,valves y41, one of/tlieV air intake Yvalves being' located'at either end of each section. vPreierablyghe air intake valves at :adjacent ends of adjacent sectionsA 21` andl 22JareVV` connected together by means of aexible conduit 42 sothat by pumping air into th'ecommon space Within all the sections, the entirehinged oatable barrier maygbe made uniformly Y buoyant when it is desired to raise the barrier and remove it to another location.

In preparing the marine drilling Yrig foundations to re- I ceive'a Asubmersible bargel in accordance; with. thezpresent with suitable means whereby it may be raised andre-vr tracted from the ocean oor without being withdrawn completely from the hinged members 26 and` 27, thus leaving all sections of the barrier hinged together'so..

invention, a plurality of vhollowiloatable. hinged members are'transportedto-,a drilling'V location.; The barrier to be I formedt the drillinglocation may be previously formed byconnectingthe several sections of the barrier together l -byhinge meansA and then towing. the oatable'barrier,

whichV may contain some water' for'ballast, to the drillingl site bymeans of. a-tug or other vessel. Alternatively, the

unhinged sections ofthe barrier maybe transported to the drillingIlocation-,ona Vbarge on which they have been stacked; inY Yunhingedv manner. On varrival ati the'rdrillinglocation, eachvindiyi'dual section 22.` ofthe'barrieris lowered into -the water and hinged to the'adjacent section until the entire barrier is formed and 'oated into position aroundthe drill site.A The dood valves .35 in. eachof the f Ybuoyant sections are then opened, allowing' the interior chamber within each section -togbeflooded with water so that the ybarrier sinks toV the bottom, of the ocean. At the same time that the Yilood Valves 35'are opened, the air intake valves 41 arefalsovented to the atmosphere.

With the Vhinged oatable barrier positioned on the ocean oor around` the drill site, spuds or piles 314 are driven down through the barrier and Vinto the ocean door to hold thebarrierin place. Thespace Within the barrier is then iilled with sand, rockor shellsflo as shown in Figure l'of the drawing. A submersible barge'll is then` oated into position above the center of the shell or rock foundation 16 and then sunk so that the bottom, of the barge 11 -rests'uponthe top of-theshells 16. If desired,

spuds 43 may be driven down through the barge to anchor it securely to the-shell foundation;

After drilling operations Ihave been completedya hin-ge pin which connects two of thexsections of the barrier may be removed so that a tug 44 (Figure 6) may attach a tow rope 45; to onesection A46 of the barrier. A source ofj pressureA (not shown) which may.l be carried by the-tug 44, Vis connectedto the 4air intake -valve 41 (Figure 4) of oneof thesections so lthat alllthe'sectionsare ooded: with' air after' which thev4 ioodevalves-'e35b are closed; After all the spuds 34'have beenY removed from therlbarrier, theentire oatable hingedbarrier may be pulledfclearofvthesand, shell' or rock' contained within thef barrier by the tug 44. It maythen bevtowedto yanother drill site. After the barrierv 13 `.(1 `igure 1') has been removed; the sand,Y shells' or rock which was contained within the barrier falls off' slightly, `as shown in Figure7, ,but still forms a substantialfoundationfof a su'icient size to permit maintenance work around. the wellhead 50; Additionally, the island of shells 16 (Fig-l ure 7) serves to some extent as a breakwater around the wellhead 50.

I claim as my invention: A n

The method of drilling a well- Yat an offshore location, said method comprising the steps of transporting to an oishore locationv a-'prefabricated oat-able barnier having la plurality of hollow iiuidtight flexibly-inter.

S connected sections adapted to be ooded, arranging said barrier to form a figure of closed periphery around' said drilling location, sinking the barrier to the ocean oor to a sufficient depth for enabling the drilling barge to be Voated over the barrier at the drilling location, filling the space within the barrier with crushed solid material, floating a drilling barge into a position disposed cen- -trally over said material, partial-ly submerging the drilling bange so that the bottom of the barge bears on the material, drilling a well from said barge, subsequently disconnecting the adacent ends of two sections of said barrier to open said barn-ier, oating said barrier, `and towing said disconnected exible barrier away from the solid materia-l it surrounds to another location.

References Cited in the file of this patent UNITED STATES PATENTS 559,116 Baldwin Apr. 28, 1896 924,362 Leow June 8, 1909 2,217,879 Willey Oct. 15, 1940 2,472,869 Travers June 14, 1949 FOREIGN PATENTS 261,246 Great Britain Nov. 1S, 1926