US2552899A - Floating drilling rig - Google Patents

Description

May 15, 1951 o. B. MANES FLOATING DRILLING RIG 2 Sheets-Sheet 1 Filed May 19, 1947 lnvemor: Oscar Manes Dg his Afiorneg:

2 Sheets-Sheet 2 Filed May 19, 1947 mm 7 me vm mm em lnvznror: Qatar 5. Manes 59 his Afl'ornzg:

Patented May 15, 1951 FLOATING DRILLING RIG Oscar B. Manes, Houston, Tex., assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application May 19, 1947, Serial No. 748,985

6 Claims. i

The present invention relates to methods and apparatus for drilling wells or boreholes into ground submerged under water bodies, such as into formations beneath lakes, shallow coastal waters, etc, and pertains more particularly to improvements in the construction and use of floating drilling rigs.

Previously, several methods for handling equipment while drilling into formations submerged by water have been employed. One method consists of mounting the drilling equipment, such as drawworks, derrick, pump, etc., on large selfpropelled barges or boats equipped and designed for drilling operations. On such boats or barges the derrick is usually mounted at one end over an open bay or Well in the boat which permits the passage of the drill or casing string therethrough. This supplies a floating base from which drilling operations are conducted, but considerable difiiculty is experienced due to the rocking action of such a base caused by wave action.

Another method consists of mounting the drilling equipment on the superstructure of a barge capable of supporting such a load. The barge is towed to the selected location at which the well is to be drilled, and, by flooding the watertight compartments, is then firmly grounded into position on the bottom so that the deck on the superstructure, upon Which drilling equipment is mounted, remains above water. Such barges are also formed with a bay or open slot in one side to permit the passage of the drill or casing string therethrough, so that when the ballast tanks are emptied and the hull raised, the barge may be floated away from the well head to another location. This method is subject to considerable limitations as to the depth of the waters in which it may find application.

It is the primary object of the present invention to obviate the use of large and expensive boats or barges in transporting the drilling rig and other equipment to the location at which the borehole is to be drilled by providing a floating drilling rig, adapted to be towed and sunk into position for drilling, and later refloated in order description taken in reference to the drawings, wherein:

Fig. 1 is a side elevation of the drilling rig showing one possible location of the flotation tanks.

Fig. 2 is a schematic diagram of an air supply system connected to one leg of the drilling rig having tanks attached thereto.

Fig. 3 is a side view, partly in cross section, of a foot assembly attached to the base of the drilling rig.

Fig. 4 is a bottom view of a foot assembly.

Fig. 5 is a perspective view showing the drilling rig in position for drilling in shallow water with the accompanying towing boat.

Fig. 6 is a top view of a fluid distribution manifold and valve assembly located on the drilling tower.

Fig. 7 is a side elevation of another embodiment of the drilling rig.

Briefly, the present invention comprises a drilling tower having at least three tubular legs and adapted to be dismantled into a number of vertical sections, a top working platform, said tower having attached to each leg an extending foot assembly, and at least one vertical flotation tank having an air port and a water port, said tanks being adapted to be filled with air, thereby causing the tower to float, or to be filled with water, thereby causing the tower to sink.

Referring to Fig. 1 of the drawings, showing a side view of the floating drilling rig or tower of the present invention, a preferred form of the tower comprises a suitable number, preferably three or four, of sloping legs It), so that the structure has the shape of a truncated pyramid having a removable pipe-pulling tripod ll and working platform l2 at the top of the legs It. Each leg [0 comprises several pipe sections such as I3, l4, l5 and. 16 which are connected by any suitable means as, for example, by pipe unions ll. A foot assembly i8 is attached to each leg It in a similar manner and is reinforced by a brace IS. The corresponding sections (for example l3) are fastened together in a rigid manner by transverse braces 28 and diagonal braces 21. The braced and connected sections of the legs thus form removable sections of the drilling tower. The individual sections of the towerare constructed to any size that is easily transported and assembled. When the desired height of the drilling tower has been determined, the proper number of sections is connected together and the foot assemblies l8 are attached to the bottom of the legs of the lowermost section.

through of a short'tubular memberzor-zjet-pipe 25 adapted to be connected to the lower section iii of the tubular leg by means of a union i2.

Located within the short tubular member 25 is a downwardly opening check valve -23swhichr prevents mud and sand from entering the tubular leg, at the same time permitting :fiuid.iwhicl'inis';v

forced under pressure down'said-tubular leg to open the check valve 26. As the check valve opens, the closure plate 5i is forced: downward i by the fluid stream which impinges on the inner surface of said plate 5'5 and jets radiallyints J the formation adjacent the foot assembly I8.

Although :the -foot .:--assembly i8 is: shown a :as

a drum-like cylinder, it is understood that it may beaofzalnypther shapa-suclras square, hexto prevent the lower end of the leg from sinking, to anysubstantial dept'nrinto the bottom." Besides actingilgas a'solid base for the drill. rig ;the foot assemblies also serveas-i:counterweights,s since a fioat'able: structure -suchasthe fdrilling trig :of thefpresen-t-invention should be=counter-weighted, 7 preferably at the bottom end, in ordereto lower the centernofngravitybelow =the :center of buoyancy- When-"it'aisndesired to? float. the; rig from one :position to 1' another: iniian upright" position; the working platfo1'm.zi2- ema l: be :securelyfixed 17031-13116 -;top {of the rig -and the-"foot assemblies, preferably; 0f ."thB*hO110W-"d1lllIl ,type, niay be filled with a weighting material. As.:sl1own-in- Fig;-, -3,T a rfoot *assembly drum-=22 may be equipped with one or more openings ins-theatoprthereof, covered by;- removable-'piate- -1neans; 58, through which Weighting materialswmay.beadded; Radial". bracesa23 'may- :be equipped "with one or rrnoreopenings 59: which: -,ailow--.an even. distribution of theweighting material in the foot assembly. Inaorder: to be-able-to .vary' the -weights-of the foot assemblies for changing operating. conditions the drums of :-'the fo'ot assemblies" may be re-. movably;filleelwithsubstances such as lead shot, small pieces .of': scrap .-metal, sand, concrete, crushedistone, etc. Insome cases-.theifoot assemblies it'- on the present drilling.rigcansbe, eliminated-so that the entire 7 base. of the. rig, comprising the-legs and the lower cross supports .1 2fi',-lcould rest on the bottom andsupport thelrig It can. be easily seen, however thatany unevene 118534012 the bottom,.whenencountered ,by one i, ofuthe. cross supports .1223 would 1 cause a ..tilt'i'rig of.-;the tower. Such a tilting,,ofl'theetdwer. is eliminated oragreatly minimized by the .iusel of. athree or four-legged tower having legs equipped with the footlassemblies above-described; l

lnlorderltol enable the .drillingtower .to'fioat; in; a body 01", water e when being ,conveyedjlto. a drilling location. the .tower .is equipped IWith'Za-V number oflwatertight,ccmpartments .or flotation,

tanks. One,embodimentlof lthe tower of the present invention is shown. in Fig; l as. having a set of. main, flotation tanks Zlflower .fiotation tanks- 28'"and upper flotation 'tanks229, with" one I seotion of the tower shownias having. no tanks" attached thereto; The tanks are 'fastenedtO. the legsections l3; idanddt'in anysuitable manner as 1 by ring clamps 3% "which readily permit the "removal "or" "any tank or group'ofi tanks for repairs or when'not'neededf The tanks may be of any shape having a horizontal cross section that is circular, triangular, square, square with rounded corners, etc. Tanks having the shape of elongated cylinders are, however, preferred as being easy to fabricate while furnishing a maximum volume with a minimum cross section, thus possessing the maximum strength to handle their-pressures involved; Each: tank is equipped with air inlet and outlet means 3! and a water inlet and outlet means 32, the air port 3 Lbeing coupled, preferably by means of a flexible conduit=33 toia suitable air supply system usually located on a towing boat or barge 31 which also carries awate'r-pumpzfi (Fig. 5). An air supply system; as sch'ematically shown in Fig. 2, comprises-an=air compressor 35, driven by a motor 4fiwandqconnectingdrive belt ll, which maintains a supply of compressed air in a supply or storage tank iaa A conduit 49, having a valve 59 located therein, is in communication with an air distributing manifold--34? having valved outlets 5t,

5 landn5z which communicate'ithrough conduits- 33 with the 1112:1112 lower28,-;or upper'ZS flotation-- tanks. respectively,=, Thus :any, amount 'of; air

necessar y lto 110817.201 level-the -tower {may be admitted to. the. fiotat-ionl-tanksbyopening :valves 53, 54 and 55 in the outlets 50, 5t and.=52;.,Closingtheqvalves153, -54=eand -55traps the air in the tanks preventing-water from entering Loutlet ports ,on. the -.tanks.'

With such a-manifold:and'valve'. assembly 34,

it, will (be.- seen. that each tank- -can be filled I ill-:1-

dividually, or; all. thertanks -in -.-any;; section can be.- filled at once, or :all the :tanks; on the; entire drilling, rig can be filleel-atmoncel iesince the tanks have individual conduitsand z'CODIlBCtiOIlS to the valve .-ma-nifold,-; the, volume; ;of air or.- 7 Water.- in* 1 thee-flotation tanks can be tadjusted to tri-m,the tower. so, that it floats in a verticalpositionz- The flexible fluid conduits-1: 33 wbetweenthe. control manifold: 34:and rthe; :flotation tanks --should: be

of :sufiicient, length. to, allowafree movement of the-towing, boat-"31's In-lpractice a.drillingrtower--of .a predetermined size is assembled-:andequipped'with the necessary number. :of flotationtanks and ,foot assemblies.- The removable working platform I 2, tripod I, I and drilling. equipment (as schematically represented at 39, Fig. 5): maybe either securely attached -to:. the top, of the tower at this time @or they f maybe-attached. after the drilling ,towerhas:beensunkI intoe-positiona The drilling ,tower-- is, then; lowered intocthe water and attached to a towing barge $.31 by means ofeav-towing cable 38.2 The fluid-conduits 33 leading from the ivalvema-ni-w fold :34 tothe flotation, tanks; 21- and-'28 are grouped and bound together to forma singlecable '1 which in turn is suspended fromrthe-towingcable:

38.\- With the .valve-manifoldt l set-to deliver air to theeflotation tanks; the.- air compressor- :isaa operated:so.that all 'Ofrrthe flotation tanks :are filled :with air. .causingzthedrilling;- rig {to-:fioate The. air valves in the -manifold 34 ;are then, closed trapping the,air in the flotationtanks and giyin'g With the tankszfill'edavitheirto provide buoy-p ancy; thei-floating tower;is.ltowed -to1: the desired location The; ain compressor 3513s \shut 'off, or the outlet-i'valve .5Eiofrom the lairlisupply tank 248 isclosed, and: theair -exhaust valve 56 :in: the

manifold is opened thusventing it to-the atmos phere.- Air- 'valves- 53;-' 5 l and 55 in the manifold system S t-are opened permitting the air to escape" from the dictation tanks or to beforced therefrom through airports 3! by water which entersthe water ports 32, flooding the tanks and thereby causing the tower to sink to the bottom. An operator controls the air valves of the manifold 34 in a manner which permits a controlled flooding of the flotation tanks so that the tower is sunk in a vertical position, as shown in Fig. 5. Drilling of the borehole is accomplished by use of a suitable pipe 40, bit 4! and water-circulating system which includes a water-hose swivel 42, a water pump 36 and a connecting flexible fluid conduit 43, said water pump being located normally on the towing boat 31. (After drilling, the shot hole is then loaded and shot or the shooting may be delayed until after the tower has been moved.)

When the drilling tower is ready to be moved to another nearby location the valve manifold 34 is set so that the air compressor 35 delivers air through the air line 33 and air ports 3| to the main flotation tanks 21. These main tanks 21,

when blown free or nearly free of Water provide sufficient buoyancy to cause the tower assembly to rise and float in a substantially vertical position if the foot assemblies 6 8 do not adhere to the bottom. If settling of the foot assemblies l8 into the bottom has occurred and adherence thereto prevents the tower from rising immediately when sufficient buoyancy is provided, the water-circulating system comprising the pump 36 and hose 43 is connected at an auxiliary connection 44 of a control manifold-valve assembly having valved conduits 45 leading from said connection 44 to each tubular leg of the drilling rig, as shown in Fig. 6. Such a control manifold assembly is located preferably near the top of the upper section of the tower. Fluid is then pumped through said conduits 43 and 45 and circulated through the tubular tower legs (or other suitable conduits) leading to the jet-pipes 25 opening at the bottom of the foot assemblies IS. The discharge of water through the check valve 26 results in a radial jetting or washing action beneath the foot assemblies l8, and this jetting is continued until the adherence of the foot assemblies to the bottom is broken, at which time the tower will rise off the bottom. Such jetting action is very effective in breaking the footing loose from the bottom in all except the most unfavorable bottom conditions.

If the drilling tower does not float in a vertical position, it may be trimmed by adjusting the volume of air in the main flotation tanks 21 and the auxiliary tanks 28, entry of air into all of these tanks being individually controlled by the manifold and valve system 34. The drilling tower, now being afloat again and in proper trim, is towed by the service-boat 31 to the next location and the cycle of operations described above is repeated.

By a proper disposition of the flotation tanks on the drilling tower structure the tower floats in a vertical position and also possesses the necessary degree of stability for being towed through the water in that position, as diagrammatically shown in Fig. 5, without the removal of the working platform, tripod, etc., from the top of the tower. The substantially vertical positioning of the elongated flotation tanks on the drilling tower is an important feature of this invention as it has been found that with the tanks in this position the drilling structure has much more stability afloat and while anchored on the bottom, particularly in offshore waters where wave and swell actions are of such height and violence as to tend to upset the tower. Vertically disposed elongated tanks have a minimum reaction to wave and swell action. With vertical disposition of elongated tanks, it is also possible to secure the greatest variability of, and control over, the center of buoyancy of the flotation system, which results in the best control over the stability of the tower when it is afloat. Simplicity of design and construction are also achieved by the vertical positioning of the buoyancy tanks. Attachment of the tanks to the tower structure longitudinally with the legs places them as far as possible from the vertical axis of symmetry of the structure and also provides for maximum differential buoyancy between tanks, thus providing for best control of this differential buoyancy in adjusting the "trim of the tower afloat. Good trim control over a floatable tower may also be secured when the buoyancy tanks surround the legs or form the legs or part of the legs 60 themselves, as shown in Fig. '7 on another embodiment of a drilling tower of the present invention. When the buoyancy tanks surround or are formed around the leg members, they may be attached to said leg members by any suitable means, as by flanging, welding, riveting or the like.

When drilling operations are conducted in waters that are too shallow to float the drilling tower in a vertical position, a tower having both upper 29 and lower auxiliary tanks 28 is used, as shown in Fig. 1, so that the tower may be floated and towed in a horizontal position. On reaching the desired drillin location the tower is either sunk in the manner described above or it is elevated into position by a cable and winch (not shown) located on the towing boat.

I claim as my invention:

1. For use in offshore drilling in combination with fluid pumping means mounted on a floating platform, a floating drilling tower adapted to be connected with said pumping means by flexible fluid conduits, said tower comprising a plurality of braced legs, separate elongated flotation tank members attached to each leg longitudinally therewith and at substantially the same distance from the ends thereof, each tank member being arranged to be selectively flooded when said drill-- ing tower is erected off-shore for operation, port means in each tank member open to the medium surrounding said tank member, port means in each tank member connectable with said flexible conduit means, whereby the buoyancy of the tower can be controlled by supplying to said tank members a fluid from said pumping means, and a drilling platform mounted on the top of said tower.

2. For use in offshore drilling in combination with fluid pumping means mounted on a floating platform, a floating drilling tower adapted to be connected with said pumping means by flexible fluid conduits, said tower comprising a plurality of braced legs, each of said legs bein at least partially formed of an elongated cylindrical tank member, port means in each tank member open to the medium surrounding said tank member, port means in each tank member connectable with said flexible conduit means, whereby the buoyancy of the tower can be controlled by supplying to said tank members a fluid from said pumping means, and a drilling platform mounted with a floating platform having air and. liquid embassies pumpingg.meansii mountedzri thereon, a a floating i; tower:adapted-rtoibericonnectedrwithL said.air:.:-and:z

saidliquidzpumping means iby; flexible. -concluits v said :tower. :comprisinga plurality ofibraced :tubu-z lair-legs; separate :elongated flotationtank meme.

bers .attached .to each-leg longitudinally there-.-

and at substantially the. same: distance .-from-- -1 the. ends. :theref,.each tank member being; are.

rangedto be selectively flooded When..said.-.drill.- 1

ing ;tOWel.-:lS erected-offeshore for .operation a flat port means..in..each.@.floating tankmember opening to.,the..,mediu'msurrounding .said .tank, port meanslin ,eachltank member connectable. to the flexible. conduitmeans to the air pumping means,

wherebythe-buoyancy of thewtower can be .con-

trolled by supplying air tosaid tankimembers' from said pumpingmeans, port .means in each leg connectable to the flexible conduit means. .to'.

the liquid pumping means, whereby a liquid may be forced through said legs and jetted through said foot "valve means; and a drilling'platform' mountedlon' the top'of said tower.

4. For use in-oifshoredrilling in combination with fluid pumping means mounted-on a'floating platformyafioating drillingtower adapted to 'be connected with said pumpingmeans by flexible at least three-legs; said tank membersbeing arranged atea-ch of-said-le'gs at substantially the same distance from the ends -thereoi'each tank membenbeing--arrangedto 'be selectively flooded when said'drillingtower iserected off shore for operation, port means in each tank member open to the medium surrounding said tank member,

port means in? each tank member-connectable' with said flexible conduit'means; whereby the 1 buoyancy of the towercan'be controlled by supplying to said tank members a fluid from said pumping means, and a platform mounted 'on said" tower.

5..Foruse in'ofishore drilling in combination- Withfluid pumping means mounted on a floatingplatform, a'floating drilling tower'adapted to be connected with said 'pumping'means byfiexible fluid fconduits; said tower comprising I a plurality of braced legs, at least two'elongated floatation tank: members: carried :longitudinally; of; 6381312 other byeach :of atleast thIBE i'18gS ,"One0f said? tank;members beingipositioned on the upper; and: one.on:.the lower?:halves.aofxeacholeg, alllioffisaid-zz upper-and all. 10f: said :lower tanks-being spaced substantiallyiequally ,fromxthe lower; ends of *saida: legs; each .tank' member :being arranged to be i selectively. flooded when said drilling toweraisx; erected ioff=shore fortroperatiom port:means .jinw:

. each tankfmemberiopening to the medium SUIFD rounding said tank 'membemxport means iriseachw tank member connectableavithsaidiflexible cone; duit means, whereby' the 'buoyancyiofxth'e tower r. canbe controlled by supplying to "said tank-meme bers a fluid from said pumping means, andz-iax platform mounted on the eupper "half 1" of said towers:

6; Foruse in ofishoredrilling-xin combination; With fluid pumping-means mountedion afloating platform; a floatingidrilling tower adapted to be connected-with said pumping ;means .byflexible fiuidxiconduits'said tower: comprising 3 a plurality of braced legs; at least "two "elongated floatation tank members carried longitudinally-10f each:: other by1each-of zat least three. legs one of said Y tank. members --being positioned-on the upperand 2 one on the l0wer halves-of each leg, all of; :said upper and all of: said loweretanksbeing spacedsubstantially equally from. the (lower ends- .of i said. legs; said :tanks on thew-lower halvesof saidlegs being of greater capactiy than. the; -tankson the upper. halves ofcasaid elegsyqeacha tank member being; arranged to rbe selectively 1 fiooded- 1 when l saidtdrilling tower. is .erectedofL-shore -for'.opera-.-. tion,. port meansin. each; tank membenppening;

REFERENCES 'JCITED The-following referencesware of -.recordin; the

file of..this; patent:

UNITED STATES PATENTS Number V Name Date 2,210,408" Henry; Aug; 6,1940 v 2,422;l68"- Kirbyi June 10,1947

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