US2612759A - Submergible drilling barge - Google Patents

Description

Oct. 7, 1952 J. T. HAYWARD 2,612,759

SUBMERGIBLE DRILLING BARGE Filed Sept. 17, 1949 3 Sheets-Sheet l z/o/m 7.'//0yw0rd INVENTOR.

Oct. 7, 1952 J. T. HAYWARD 2,612,759

SUBMERGIBLE DRILLING BARGE Filed Sept. 17, 1949 3 Sheets-Sheet 2 HWIIH (/o/m Z Hayward- INVENTOR.

Oct. 7, 1952 J. HAYWARD SUBMERGIBLE DRILLING BARGE Filed Sept. 17, 1949 3 Sheets-Sheet 3 i In 'umnm 1- s 1- w I '/7 I iMlll Illl nu 1 dob/7 I Ha /Word INVENTOR.

Patented Oct. 7, 1952 UNITED E. S- PATENT OF F ICE SUBMERGIBLE DRILLING BARGE John T.- Hayward, Tulsa, Okla.

Application September 17, 1949, Serial No. 116,327

2 Claims;. (Cl. 6146) 1 This invention relates to improvements in drilling barges, particu1arly tobarges of the submergible type which are adapted especially for use as drilling rig foundations in open-ocean areas.-

This application is a continuation-in-part of mergence is begun from one end of'the hull, the

opposite end being maintained in buoyant condition and extending above the water'surface until the submerging end has come to rest on the water bottom, after whichthe extending end is submerged to bring the entire'hull to rest on;t he

bottom. A SimiIar procedure is followed in raising the barge hull, that is, one end is first rendered buoyant and raised to the surface while the 'opposite end'remains on bottom'to maintain the hull in stable condition until'the rising endhas attained stabilizing buoyancy, and then the submerged end is rendered buoyant to again bring the'entire structure to the fully floating position.

The present invention'has for its principal ob jects the provision of an improved barge structure which isparticularly adapted 'for submergence and raising by the one-end-first method; which may be employed with high degree of-s'afety and stability in water depths exceeding the molded depth of the hull, as well as in water depths less than the molded depth of the hull; Which is particularly compact and eflicient in design; which may be constructed with considerably reduced quantities of material and at lower cost than earlier designs; and which has a high degree of stability both afloat and on bottom and during submergenceand raising.

Other and more specific objects and advantages of this invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings which illustrate useful embodiments in accordance with this invention.

The principles involved in the design of a submergible hull in accordance with this invention will be first described in connection with Figs. 1, 2 and 3 which are more or less diagrammatic illustrations in profile of a conventional hull shape and of several shapes and arrangements in accordance with several embodiments of this invention;

Barge hulls of the designs whichxare convenk tionallyx employed as drilling rig foundations for water drilling are ordinarily constructed in the form of rectangular box-like structures of gen erally uniform molded hull depth, having agenerally fiat bottom and a generally fiat'deck -diS- posed in parallel relation to the bottom; When 1 such hulls are submerged or raised usingthe one-- end-first techniquedescribed m the aforesaid c0-- pending application, the end-portion-whichis kept" buoyant and remains afloat while the opposite end is being submerged will", due to the-inclinationof the hull, necessarily extend for a substantial distance above the Water surface. Due to the gen erally rectangular shape of theconventio'nal hull and the inclination of the latter duringsubmergenceand raising, the extending section will have a generally triangular shape in profile; the water'surface from which-it emerges forming the base and the apex being-the upper corner of the hull. Thiscondition is illustrated in Fig. 1 in whicha profile of a conventional rectangularhull' H is shown in broken linesin thenormal fully" afloat, and fully submerged positions with respect to a water surface W, and insolid lines showing the partially submerged inclined position-at which one endof the hull is in contact with the land bottom L'during submergence-and raising; It will I be seen that the triangularsection ACB of the hull extends above water level W; the line AB-indicatin thewater plane of the hull when "inthis position.

I have found that the stability of 'a'submergie ble hull will be increased if the triangular section ACE is, in effect, sheared ofi, 'Infactgbecause. the center of gravity of the section .of the hull above the line AB will be abovethe center of buoyancy of the submerged hull','the section ACB actually reduces the stability ofthehull. By eliminating the section. ACB, the center of gravity will be lowered, thereby increasing the stability and at the same time substantiallyreducing,

the total quantity of steel androther. construction material and expense-which would berequired in l the construction of a conventional rectangular hull of the same overall'dimensions such as that illustrated in Fig. 1. Other advantages also result from this change in hull design, .as. will :be pointed out more fully hereinafter.

Fig. 2 is a diagrammatic profile view of ahull,

in accordance with one embodiment o-fthiszinvention wherein'the section .ACB of Fig. 11.11315 been removed and showing the thus-modified hull in the several positions corresponding to those illustrated in Fig. 1. It will be seen that when the hull is in the fully afloat position, the rear portion having the now upwardly sloping deck DD', will still provide substantial hull volume which will extend well above the water surface, thereby providing adequate stability in the floating position and during the several stages of submergence of the opposite end of the hull until the latter is in physical contact with land L, as shown in full lines in Fig. 2. In the latter position, it will be seen that the sloping portion D-D' of the deck has assumed a position substantially parallel to the water surface and only a very small rectangular section of the hull extends above the water surface. Since this section will be maintained in buoyant condition until the opposite end touches bottom, the hull remains fully stable and. as soon as the submerged end lands on bottom, the direct contact between the hull and the bottom will stabilize the hull against any rolling movements, so that the buoyancy in the floating end no longer is important to maintain stability. It is only necessary to then destroy the buoyancy of the floating end to cause it to sink so as to bring the entire hull to the fully submerged position as illustrated.

The same stability control occurs during raising. The sheared or sloping end will be rendered buoyant to raise it while the other end is kept ballasted to hold it on bottom until the sloping end has risen to the surface and is buoyantly stable, whereupon the submerged end is deballasted to render it buoyant so that it will rise to the surface to thereby re-float the entire structure.

The angle at which the hull deck DD (and the associated portion of the hull) is sloped upwardly relative to a horizontal plane, such as the plane of the hull bottom, will be determined ordinarily by length of the hull and the depth of water in which it is designedto be operated. This angle may be made substantially equal to the angle of inclination of the hull when the opposite end is on bottom. These angles are indicated respectively at :1: and y in Fig. 2. When angles a: and y are equal, it will be evident that deck portion DD' will be substantially horizontal and parallel both to water surface W and land bottom L when the hull is in the inclined position shown in solid lines in Fig. 2. It will be understood, however, that considerable latitude may be exercised in determining the angle at which the end section of the hull is to be sloped.

In accordance with another embodiment of this invention, both end portions of the hull may be provided with the sloping or angular configuration previously described without materially affecting the stability of the hull during submergence or raising and thereby efiecting additional savings in material and construction cost. Fig. 3 illustrates diagrammatically the profile of a hull in accordancev with this embodiment, showing such a hull in the several positions corresponding to those illustrated in Fig. 2. In this embodiment it will be seen that the hull sections D-D' and D'--E slope upwardly from the opposite ends of the hull, joining at the point D which is located generally in the midship portion of the hull, but not necessarily at the exact mid-point thereof, and may be off-set from the longitudinal mid-point of the hull, depending generally upon the loading in the opposite end portions of the hull and its general design.

.Figs. 4, 5, 6, and 7 illustrate in greater detail a design of submergible drilling barge structure embodying the above-described hull principles and conforming generally to the modification illustrated particularly in Fig. 3.

The hull H is a hollow, box-like structure, generally rectangular in plan, and is composed of a generally flat, horizontally disposed bottom [0, connected to upstanding side walls H-ll and end walls [2-12. The upper edges of side walls llll slope upwardly from their opposite ends to a juncture point, indicated at D, located at an intermediate point between the ends of the hull. A deck, composed of oppositely sloping portions l3-l 3, is laid over the sloping upper edges of side walls lll I, having its side edges connected thereto and its end edges connected to the upper edges of end walls l'2-l2 to fully enclose the hull. One end of the hull, which will be designated as the bow for purpose of easier description is provided with an arcuate rake I4, curved about a relatively large radius, which serves, when in contact with the land underlying the water body in which the structure is operated, as a pivot about which the hull may rotate during raising and lowering by the one-end-first technique.

The hull is provided with a longitudinal slot l5 which extends inwardly of the hull from the bow generally along the longitudinal axis of the hull for a considerable portion of its length, to form the conventional drilling slot commonly provided in drilling barges.

The interior of the hull is divided by means of a plurality of bulkheads |l|1 into a suitable number of ballast compartments 18-48 of any desired sizes and arrangement. A compartment l9, located generally in the mid-ship portion of the hull and aft of the inner end of drilling slot I5, may be employed as a machinery space, engine room, pump room, or the like, in which suitable and generally conventional ballast-handling in a suitable longitudinally and laterally spaced pattern adapted to support on their upper ends a working platform 2| on which may be mounted the usual drilling derrick 22 and other drilling machinery, and on which may be mounted an enclosed housing 23, which may serve for crew quarters, machinery rooms and the like. The derrick 22 will be centered over the inner end of drilling slot I 5 through which access is thus provided to the underlying land for the drilling tools operated from the derrick, and which provides means for withdrawing the structure from about the well when drilling is completed.

Supporting columns 28 may be of any suitable shape and arrangement and are preferably of hollow cylindrical shape, as a minimum number of cylindrical columns of appropriate cross-sectional area will provide adequate support strength for the platform load without requiring any crossbracing, thereby decreasing the weight, complexity and cost of the platform-supporting structure and, at the same time, increasing to a maximum degree the wave-transparency of the platformsupporting structure. Such wave-transparency is an important consideration in employing barge structures of the type described for drilling in open ocean areas. The hollow bores of columns 20 may also be employed as communication trunks between platform 2| and the interior of the hull to provide means for access thereto by personnel when the hull is submerged and for stringing water, fuel oil, power lines, and the like between the platform and the hull. Columns 20 will be made of such length as to extend well above the surface of the water body in which the hull is to be submerged when the hull bottom is resting on the underlying land. Platform 21 may thus be supported at a suificient height above the water surface so that operations conducted therefrom will not be subjected to changes in water level by tides, waves and other water surface movements.

The drilling barge structure, constructed as above described, will be floated to a water location in any suitable and conventional manner, and will be fully stable while afloat. When the drilling location is reached, the hull will be submerged employing the one-end-first technique, described in my aforementioned application, Serial No. 65,475, to safely place the hull in position on the underlying land and as noted previously, the structure will be fully stable when the hull is submerged by that procedure. When drilling has been completed the structure may be refloated again using the one-end-flrst procedure with complete safety throughout the raising operation.

If desired, additional stabilization of the hull may be provided during the various operating stages by means of supplementary submergible hull sections or pontoons, which may be ranged along the sides of the hull, particularly along the portion Which is last to be submerged and the first to be refloated. Such hull sections or pontoons may be constructed and operated in the manner disclosed in my co-pending application, Serial No. 44,626, filed August 17, 1948.

Submergible hulls in accordance with this invention possess a number of important advantages, in addition to those previously mentioned, over more conventional types of hulls when employed as submergible foundation for drilling rigs operating in open ocean areas. The novel shapes permit substantial reductions in the height dimensions of the major portions of the hull and this, in turn, permits the hull to be more readily braced internally and made much stronger so as to resist relatively high collapsing pressures. As a result hulls in accordance with this invention may be safely used in much deeper water than hulls of more conventional designs.

Moreover, hulls designed in accordance with this invention may also be used with safety in water depths shallower than the maximum molded depth of the hull. This provides a great degree of flexibility in employment of such hulls, particularly in open ocean areas where such structures are ordinarily subject to numerous and often widely changing water levels such as result from wave movements and changes in tide levels.

When the more conventional flat-decked hulls are submerged in water of insuificient depth to keep the hull fully submerged at all times, a portion will protrude above the water surface which will have a relatively large water plane generally equal to the transverse area of the hull. As a result such hulls are subjectto being raised off bottom by every passing wave or raise in tide, a condition which is extremely hazardous for drilling. On the other hand, with a hull designed in accordance with the present invention, as for example, the design illustrated in Fig. 4, the hull volume, which will extend above the water level, is much less than in the cases of conventional hulls. Moreover, due to the triangular profile of the hull, any rises in water level will be accompanied by a rapid reduction in the water plane and the tendency, therefore, of the hull to lift with each passing wave or tide rise will be greatly reduced. Furthermore, when used in shallow water, the sloping deck will greatly reduce the under-cutting action of waves breaking over the ends of the hull, thereby additionally contributing in an important respect to the safety of the drilling operations being conducted from the structure.

It will be understood that various alterations and changes may be made in the details of the illustrative embodiments of this invention within the scope of the appended claims but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A submergible drilling barge, comprising, an enclosed generally rectangular hull having a substantially flat bottom, and having its upper side portions sloping upwardly from at least one end toward the mid-portion of the hull at an angle to the bottom determined by the length 01 the hull and the depth of a water body in which it is submerged, said angle being such that the hull volume at said one end which extends above the surface of the water body when the opposite end of the hull is resting on bottom approaches a minimum.

2. A drilling barge according to claim 1 wherein the upper portion of said opposite end slopes upwardly toward said mid-portion at substantially said angle.

JOHN T. HAYWARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 712,002 Packard Oct. 28, 1902 720,998 Becker Feb. 1'7, 1903 1,306,322 Waters June 10, 1919 1,341,289 Thurston May 25, 1920 1,346,743 Fink July 13, 1920 1,681,533 Giliasso Aug. 21, 1928 2,200,661 Templeton May 14, 1940 2,334,992 Crake Nov. 23, 1943 2,551,375 Hayward May 1, 1951

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