US3128604A - Off shore drilling rig - Google Patents

Description

April 14, 1964 w. A. sANnBERG OFF SHURE DRILLING RIG 5 Sheets-Sheet 1 ,J5 lI3 Filed May 16, 1960 IN1/TOR. mL/Au sA/vasen@ Mw/@z5 .4' y Tranne-fs April 14, 1964 w. A. sANDBERG 3,128,604

OFF SHORE DRILLING RIG Filed May 16, 1960 5 Sheets-Sheet 2 [Il "M INVENTOR. W/LL /AM A. SANDBERG I BWM/W ATTORNEYS April 14, 1964 w. A. SANDBERG oFF SHORE DRILLING RIG 5 Sheets-Sheet 5 Filed May 16, 1960 INVENoR. w/LL IAM A. SAA/ossea "Wwf/@h Afro/ws rs w. A. SANDBERG oFF SHORE DRILLING RIG April. 14, 1964 5 Sheets-Sheet 5 Filed May 16, 1960 INVENTOR. WLLH SNDBERG BYf-j l Arron/v5 rs United States Patent O 3,128,604 OFF SHORE DRILLING RIG William A. Sandberg, 325 Orange Grove Ave., Pasadena, Calif. Filed May 16, 1960, Ser. No. 29,404 1 Claim. (Cl. 61--46.5)

This invention relates generally to off-shore drilling apparatus, or other off-shore installations and more particularly concerns novel off-shore drilling equipment and methods of installation which contribute to the overall eliiciency and operation of the equipment, and in general provide for a highly practical and desirable off-shore drilling set-up.

As broadly conceived, the invention concerns itself with the installation, construction and operation of a caisson shell structure which is adapted to be erected so as to stand lengthwise vertically above and below the off-shore water level with caisson weight supported on the underwater formation. The caisson structure contains a central cavity for bulk storage of liquid, the caisson hollowness also enabling lioating of the unit to desired drilling location and contributing to the facility with which the floating caisson may then be sunk into upright position and lowered to installed position, as will be described. Moreover, the caisson snell structure, which is desirably but not necessarily cylindrical, contains lengthwise or vertically extending Well passages spaced about the central cavity through which access may readily be had from above water level to the underwater formation, as for purposes of drilling and also installing well casing or piles downwardly into the underwater formation.

More particularly, and as regards the installation of the caisson structure discussed above, the invention provides for the loosening and removal of formation material directly below the caisson shell structure, so that the latter may be sunk to desired depth within the formation and anchored therein. Typically, hydraulic jetting means is provided for jetting water under pressure into the formation to loosen it below a partition or partitions extending across the lower exterior of the caisson cavity, and conduit means is provided to communicate with the lower interior of the caisson cavity below the partition means for the purpose of conducting upwardly the loosened formation material, as will be described. In addition, such lowering of the caisson is assisted by the weight of liquid controllably received within the caisson cavity interior, such weight being transferred to the shell structure, the lower rim of which is adapted to cut downwardly into the formation. After lowering the caisson to desired depth, drilling or equipment strings may be advanced downwardly through the caisson shell passages t drill passages in the formation below the caisson shell, for the reception of the previously referred to casing or piles, these coming to rest in anchoring position within the caisson and formation passages, as will be described.

Referring more speci'cally to the operational configuration of the novel off-shore drilling equipment, the invention contemplates the filling of the caisson lcavity with ballast liquid exerting outward pressure against the shell which tends to balance the vsea water pressure exerted against the shell exterior. Such ballast liquid may include stored crude oil and also sea water, or either one of these, the crude oil being generally confined above the ballast sea water and in contact therewith. As will be described, axially spaced bulkheads or partitions extend across the caisson cavity interior to form a vertical series of compartments receiving the ballast liquid, these compartments being in constant` or continuous series intercommunication. As a result, the ballast liquid adds to the stability of the caisson whereby no guide lines or anchors 3,128,604 Patented Apr. 14., 1964 ICC are needed to hold the caisson in upright finally installed position, even though deck structure mounted on the casing above the water surface overhangs the caisson to considerable extent.

In addition, and again referring to the operational configuration of the equipment, pumping means is provided having an inlet within the lower interior of the cavity for removing ballast sea water from below the crude oil as the latter is filled into the upper interior of the cavity for storage. A typical caisson may have a cavity diameter of around 50 to 80 feet, and a storage height of around 200 to 300 feet, which represents a storage capacity of say around 90,000 barrels of oil. Also pumping means is provided to have an inlet within the upper interior of the cavity for removing stored crude oil from above the ballast sea water as the latter is received into the lower interior of the cavity. Accordingly, it will be seen that the caisson may be readily filled with crude oil or sea Water, and emptied las desired, all in such manner as to maintain the caisson suitably filled with ballast liquid at all times and counterbalancing the external pressure of sea water against the caisson. As will be seen, the caisson shell structure typically comprises concentric inner and outer steel cylinders suitably reinforced, the interval between the cylinders being filled with light weight concrete containing well passages which are circularly spaced to enable placement or location of well pumping apparatus on the deck structure to greatest advantage. The shell is structurally stable against radial collapse even when fully submerged and with no liquid inside. Also, the invention incorporates such novel features as a floating elevator platform which may be raised and lowered between the deck structure and the sea surface for transferring loads therebetween, and other advantageous arrangements of equipment associated with the installation and operation of the drilling rig.

These and other advantages and objects of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following detailed description of the drawings, in which:

FIG. l is a side elevation of the caisson shell structure, as it is towed to the drilling site;

FIG. 2 is a side elevation similar to FIG. l showing a shell structure partly sunk at the drilling site;

FIG. 3 is a side elevation of the shell structure as it touches the sandy bottom of the ocean during installation;

FIG. 4 is a fragmentary side elevation showing further sinking of the shell structure into the sandy strata;

FIG. 5 is -a fragmentary side elevation showing still further sinking of the shell structure into the formation;

FIG. 6 is an enlarged side elevation in which the installation of the caisson has progressed to the extent shown in FIG. 5 and illustrating the details of formation removal below the caisson;

FIG. 7 is a section taken on line 7-7 of FIG. 6;

FIG. 8 is an enlarged fragmentary side elevation of the portion of FIG. 6 indicated at line 8 8;

FIG. 9 is a view like FIG. 8 showing an alternate construction; K

FIG. l0 is a section taken on line 10-10 of FIG. 6;

FIG. ll is an enlarged fragmentary section taken on line 11-11 of FIG. 10;

FIG. l2 is an enlarged fragmentary vertical section taken through the caisson vshell structure of FIG. 6 and illustrating the detailed construction of structure asssociated with the well passages in the shell at different elevations, the passages containing guide pipe and well casing or piling;

FIG. 13 is a fragmentary vertical elevation, partly broken away, showing an alternate construction of the lower extent of the caisson shell structure which is installed in the underground formation;

FIG. 14 is a vertical section taken through the installed caisson together with deck structure and pump operating equipment mounted thereon; and

FIG. 15 is a plan view of the FIG. 14 deck structure and illustrating a typical arrangement of pump operating equipment at the Well heads.

In FIG. 1 the caisson shell structure generally indicated at 1t) is shown oating in the ocean with the caisson extending generally horizontally. This is the preferable configuration in which it is launched and towed as by line 12 to the drilling site. FIG. 2 illustrates the caisson being controllably sunk toward upright position at the drilling site, compartments 13 within the caisson cavity interior being progressively hooded starting from the lowermost end 14 of the caisson to reduce the buoyancy of the caisson. The compartments are formed by bulkheads or partitions 15 designed for static head in towing position, which generally extend crosswise of the caisson interior, and are spaced lengthwise thereof as shown. As the caisson is sunk, the head structure 16 thereof is lifted out of the water to uppermost position as is seen in FIG. 3. At this stage of the installation, the caisson extends vertically with the lower end thereof touching the sandy bottom or strata 17 without exerting substantially downward pressure, temporary guys connected to the head structure 16 and suitable anchors, not shown, being set to align and plumb the caisson for further lowering or sinking accompanied by decreasing the caisson buoyancy.

Reference to FIG. 4 illustrates the progressive lowering of the caisson into the sandy strata 17, and FIG. shows the shell structure after it has been sunk completely through the strata 17 and into the shale formation 19 underlying the sand. During such sinking of the caisson the weight of sea water admitted to the compartments 13 is transferred to the shell of the caisson to aid penetration of the lower rim 20 of the shell into the sand and shale formations, as will be described.

Referring now to FIGS. 6 through l2, it will be observed that the caisson generally includes inner and outer concentric steel shells 21 and 22, the space between the shells being filled with light-weight concrete 23, except for vertical well passages 24 which are formed by the guide pipes 25, the latter being bonded to the cement. Also suitable radial reinforcing webs 26 are shown in FIG. 10 as interconnecting the inner and outer shells 21 and 22 at intervals around the cylindrical shell structure. Well passages 24 provide access to the underwater formation through the caisson shell structure in order that the interior of the shell or cavity may be left freely open for bulk storage of liquid such as crude oil or sea water without corrosion of well pipes in the cavity. Also, the arrangement of the passages 24 adds substantially to the facility with which the drilling and pumping apparatus may be operated on the deck structure supported by the caisson, all of which will be described.

It will also be observed that smaller pipes 27 are embedded in the concrete 23 to extend vertically and terminate at jetting nozzles 28 located near the lower rim 20 of the caisson steel shell 22. These nozzles project below the level of a batiie 41, which extends generally across the lower interior of the caisson, directly above the formation extent 30 which is subject to loosening and removal. Such loosening is effected by hydraulic excavation of the formation under the jetting action of liquid directed under pressure through the nozzles 28. Typically, water under pressure is delivered to the pipes 27 from an annular header 31 within the upper interior of the caisson structure, valves 32 being located in series with the pipes 27 for controlling the amount of water delivered to the nozzles. As is clear, the jetting nozzles are spaced circularly about the lowermost interior portion of the caisson, the pipes 27 also being circularly spaced about the shell structure. Pairs of pipes 27 may be spaced radially as in FIGS. 6, 8 and 9, or circularly as viewed in FIG. 10. Water is supplied under pressure to the header ring 31 through a delivery pipe 33, the intake 34 of which is below sea level 35. A suitable pump 36 may be carried on a barge 37 or on other structure, and is connected in series with the pipe 33 and supplies the needed pressure.

Again referring to FIGS. 6, 8 and 9, it will be observed that a solid partition assembly 38 extends across the lower interior of the caisson shell structure. The assembly 38 typically comprises upper and lower batlies 40 and 41, the space therebetween being filled by concrete 42, the weight of which acts during installation of the caisson to aid sinking of the lowermost end thereof when the compartments 13 are successively llooded.

Communicating with an annular space or zone 39 above bale 41 are the discharge ends 43 of compressed air delivery lines 44, these extending downwardly near the center of the cavity, and being supplied with compressed air as by a suitable compressor 45 delivering to a line 46 which connects through a valve 47 with the lines 44. The compressor 45 is typically carried by the operating barge 37 anchored adjacent the caisson structure being installed in position. The space or zone 39 also com municates with an air lift conduit 4S extending centrally upwardly within the caisson cavity to an elevation above sea level 35 and then turning at elbow 49 to discharge at 50 into the sea through an opening 51 in the side or shell of the caisson. This opening may be covered as de sired by a sliding door or closure 52 adapted to be dropped over the opening 51 by means of a winch line 54 supporting the closure.

Communication of space or zone 39 with the air lift conduit 48 is through perforations 54 in the lower end portion of that conduit, and it will be understood that the compressed air delivered to the zone 39 mixes with the water owing upwardly through the central air liftl conduit 3S at pressure considerably reduced in relation to the hydraulic pressure in the excavation zone 55 beJ low the baflle 41. Accordingly, the mixed water and air enter the air lift conduit 4S and rise therein, this action tending to draw the excavated or loosened material upwardly through the open lower end 56 of the conduit 4S for entrainment and removal, the consequence of which is discharge of the loose material into the ocean outside the caisson. Accordingly, the hydraulic jetting action and delivery of compressed air to zone 39 culminates in progressive removal of the forrnation directly below the caisson structure, facilitating controlled sinking thereof initially through the sand strata layer 17 and ultimately into the shale strata 19 to desired depth. This action is aided as discussed above, by the weight of the ballast liquid received into the cavity interior of the caisson, and particularly the compartments 13 therein, as by entrance of sea water through a sea valve 57 carried in the side or shell structure of the caisson below sea level. For this purpose it will be observed that the bulkheads 15 contain ports 58 placing the compartments 13 in intercommunication so that liquid tends to till the caisson interior from the bottom up as controlled by the opening of the valve 57 communicating with a vertical pipe 97 which discharges at 99. The weight of such liquid is transferred from partition assembly 38 to the lowermost extent of the shell structure indicated at 59, which weight is then aplied to the cutting rim 20 of the outer steel shell 22. Accordingly, penetration of the caisson shell into the underwater formation is controllable by admitting water into the caisson cavity to adjust the Weight imposed on cutting edge 20, and is further aided by the considerably reduced pressure within the excavating zone 55 occasioned by the operation of the air lift mechanism previously described, thereby to increase the loading exerted downwardly at the cutting edges 20 of the caisson shell. Therefore it is clear that the caisson structure may be sunk under complete control to any desired depth, at which point the caisson may be anchored in position as will now be described.

Referring to FIG. l2, the caisson structure is therein shown as having penetrated the formation 19 to desired depth. Grout or cement may then be jetted through pipes 27 and nozzles 28 to a degree suflicient to cement the lower end of the casing to the formation, or to form a seal preventing access of sea water to the formation to be drilled. Concomitantly, low pressure is maintained in the zone 55 since sea water penetration thereto is stopped or materially slowed by the cement seal. Following this stage of installation, the formation is drilled out to form a circularly spaced series of wells y60 extendingly directly below the passages 24 through which drilling equipment is lowered to form the wells 60. Thereafter, pipe casing 61 or piles are lowered through the passages 24 and downwardly into the wells 60 for purposes of permanently anchoring the caisson shell structure in position. In furtherance of this objective, the piles are cemented at 62 to the formation 19 as by introducing cement into the piles 61.

Thereafter, the anchored piles 61 are placed in tension as by turning of jack screws 64 near the upper end portions of the piles. The jack screws are typically in threaded engagement with slip-on flanges 65 to which the casing is suitably attached at 66, as by welding. The lower ends of the jack screws bear against a ring flange 67 supported on the tops of the guide pipes 25. Following such pre-tensioning, cement or grout may be introduced into the clearances 63 between the casing and guide pipe to bond the casing to the latter. Accordingly, the casings remain in tension exerting downward loading on the caisson structure to anchor it into the formation 19. This increases the stability of the caisson structure, which is desirable from the standpoint of resisting overturning loads exerted by waves breaking against the exterior surface of the casing. The guide pipes 25 are seen in FIG. l2 to be connected by reinforcing webs 68 to the inner and outer metallic shells 21 and 22 of the caisson structure. Also, a drill string 160 is shown run into the hole within casing 61, the string extending downwardly into the formation below the casing 61 and cement body 62. Finally, a sea level bulkhead deck is indicated at 69 below the pre-tensioning bolts or jack screws 64.

Referring now to FIG. r13, a slightly modied caisson structure is shown to include an outer metal shell 22 having an enlarged lower extend generally illustrated at 70. An upwardly and inwardly tapering plate 71 extends inwardly from the lower rim 72 of the shell portion 70, and it will be appreciated that greater stability is giventhe entire caisson structure by virtue of the enlarged transverse dimensions of the shell structure which is set into t-he formation `73. In other respects the caisson structure remains essentially the same as previously described.

Reference to FIGS. 14 and 15 shows the caisson structure containing operating equipment and mounting a deck structure 74 from which pump equipment is operated. The previously described sea valve 57 is shown to be operable as by a hand wheel 75 mounted on the lower deck 76 of the structure 74, the latter being supported on the head structure 16 of the caisson. Also supported on the deck 76 are two motor units 77 and 78 operable to drive rotary pumps '79 and 80 within the caisson. Pump 79 is located at the lower end of a discharge pipe S1 which extends downwardly through the caisson from the motor unit 77, the pump 79 having an intake 82 at the general level of the partition assembly 28, i.e., at the lowermost interior portion of the caisson. Operation of pump 79 results in the removal of storage or ballast liquid from the caisson interior cavity and discharge of such liquid through a branch line 83, discharging to the exterior of the caisson above sea water level. As will appear, the principal purpose of the pumpV 79 is to empty ballast liquid from the lower interior of the caisson for inspection purposes, or to empty sea water from the lower interior of the caisson to permit increased crude storage. Valve 6 84 in line 83 is controllable as by the hand wheel 85 which is mounted on the lower deck 76.

Pump has an inlet 86 at the lower end of a discharge pipe 87 extending vertically below the motor unit 7S, the inlet 86 being at or near the average level of the ocean surface 35. Operation of pump 80 serves to remove crude oil from the upper interior ofthe caisson for discharge through either of lines 88 or 89 branching from the discharge pipe 87. It will be understood that line 8S represents discharge of crude oil to a barge or other surface vessel, whereas line 89 is usable tovconduct the crude oil to an underwater pipe 90 on the ocean bottom, that pipe generally running to the shore and being in series communication with suitable temporary storage tanks. Storage of crude within the caisson may, of course, obviate the need for line 90 and shore temporary storage. Suitable expansion joints 91 are shown connecting lines 89 and 90 at the exterior of the caisson structure 10 near the ocean bottom. In this regard, it will be ovserved that the caisson structure contains a divers door 92 and mounts an outside ladder 93 near the Ocean bottom, this equipment being usable to permit access through the caisson wall for purposes of inspecting the piping within the lower extent of the caisson structure, and also the expansion joints 91. Suitable valves 94 and 95 are connected in series with lines 88 and 89 as shown for purposes of controlling the flow through these lines, controls 96 and 96a for these valves being supported on the lower deck 7 6.

It should be mentioned that opening of the sea valve 57 permits sea water to enter the caisson through branch line 96 which connects into vertical pipe 97. The upper and lower ends of that pipe are open to the exterior and to the lower interior of the caisson at 98 and 99, and another valve 100 also operable by control 75is connected in series with the pipe 97 generally above the ocean surface level. As a result sea water can flow into or out Of the shell through the pipe 97 when the valves 57 and 100 are open, whereas closing of these valves prevents flow through the line 97.

The uppermost deck 101 of the structure 74 is adapted to support a number of pump operating units 102 of con- Ventional type, these being conveniently arranged as shown in FIG. 15 at the heads of the well pipes or casings 61, the latter generally extending upwardly from the well passages 24 previously described. The casing heads are generally circularly spaced as seen in FIG. 15, which permits a generally circular arrangement of the pumping units 102 both inside and outside of the circle den'ed by the casing heads 61. It is clear from the showing of FIG. l5 that this arrangement has very great utility in many respects, including the advantage that access to the pumping units may readily be had with minimum interference from other pump operating units. In addition, some or all of the units may be moved away from over the well heads to permit movement over the 'casing heads of a drilling rig, the legs of which are shown at 103 mounted upon a platform 104 which is skidded over the deck 101. The usual draw works is indicated at 105 mounted on the platform 104, as are the compound transmission 106 and engines 107.

An intermediate deck 108 below deck 101 and above deck 76 may be used to support necessary piping and socalled Christmas tree valve assemblies, not shown, in series connection with the casings 61, it being clear that ready access may be gained to such piping by workmen at the level of deck 108. Also, blowout prevention equipment may be mounted between the top and bottom decks 101 and 76.

Generally speaking, the crude oil ilowing upwardly within casings 61 is discharged through branch lines 109 having outlets 110 within the upper interior of the caisson, above the level of the upper bulkhead 69, all for the purpose of storing crude oil within the caisson interior. Since the oil is of lesser specific gravity than sea water,

it stands on and over any sea water ballast within the caisson interior, and accordingly, as crude oil is continuously discharged into the caisson, sea water flows from the lower interior of the caisson through line 97 and open sea valve 47 to the caisson exterior, all for purpose of maintaining a pressure balance as between liquid pressure exerted against opposite sides of the caisson shell. Crude oil is pumped in until the oil level is above the sea surface level and above pump 80, and during such storage of crude the sea valve 57 is closed. When it is desired to remove the stored crude from the caisson the pump 80 is operated to move the oil to a tanker through line 88 or to the underwater line 90, and the sea valve 57 is kept open during such removal to allow sea water t flow back through the caisson structure filling it from the bottom up. When all the oil has been removed from the shell, the water levels inside and outside the caisson are approximately the same, i.e., at sea surface level, the suction end or inlet 86 of the pump 80 is exposed, and pumping through lines 88 and 89 will cease. In this connection tide and wave action will vary the height of the water level within the caisson so that in some instances not quite all the crude will be removed from the caisson interior. Also the shell interior can be cornpletely emptied by closing the sea valve 57 and by removing liquid as by means of pump 79. The storage of crude in the caisson as described has the added advantage that emulsified oil and water pumped from wells into the caisson tend to separate within a zone intermediate the main bodies of stored crude and sea water.

FIG. 14 also illustrates a heliport landing 110 for helicopters transferring personnel to and from deck structure 74, and pipe rack area 120. Also, elevator means is generally indicated at 111 for transferring loads vertically between the deck structure '74 and sea surface, exterior of the caisson structure, as for example transferring personnel from the barge to the deck structure. The elevator means includes a hollow guide column 112 at the lower end of which a platform float 113 is suspended. Winch means 114 is operable by means of winch line 115 connected to the platform float to lift and lower the guide 112 and platform float 113 between the lower deck 76 and sea level. Suitable guide rollers 116 are shown in engagement with the vertical guide column 112 for keeping it vertically aligned during elevation and lowering of the platform 113 as by tidal or wave action. In case of storms, the platform float 113 may be raised by winch 114.

In the event it becomes necessary to remove the caisson structure, the casings 61 are severed at or near the lower end of the caisson, as by detonating explosives therein, liquid is pumped out of the caisson interior so that buoyant force is created, and pressurized liquid or gas is pumped through conduits 44 to exert added upward thrust against the partition assembly 38. For this purpose, the upper end of air-lift tube 48 may be capped or sealed.

I claim:

Off-short equipment, comprising a caisson in the form of a tubular column standing lengthwise vertically above and below the offshore water level and supported by the underwater formation, the column including inner and outer tubular metallic shells which are spaced apart, guide pipes extending upwardly in the space between the shells, concrete-like material in said space attaching the guide pipes to the shells and bonded thereto, the caisson having a vertically thickened partition extending laterally across the lower interior thereof, means including other pipes extending downwardly within the caisson for jetting water beneath said partition to excavate and break up the formation material during installation of the caisson, means for flowing said jetted water and broken up formation material in a stream directed upwardly and for jetting air into said stream to effect lifting of the material upwardly through the partition for discharge, tubular casings within said guide pipes and projecting downwardly into the underwater formation below the caisson, means anchoring the casings to the formation and attaching the casings to the guide pipes to hold the casings in tension so that the casings exert loading acting to urge the caisson downwardly, said last named means including holding material extending in spaces formed between the casings and cylinders defined by the bores of the guide pipes, superstructure carried by the caisson, generally circularly spaced conduit strings extending upwardly from the formation into the casings and upwardly therein, and equipment on the superstructure for cooperating with the conduit strings to effect passage of fluid therein vertically of the caisson.

References Cited in the file of this patent UNITED STATES PATENTS Re. 4,953 Sickles June 18, 1872 480,127 ORourke Aug. 2, 1892 669,192 Whisler Mar. 5, 1901 782,557 Hadlock et al Feb. 14, 1905 1,853,379 Rotinoi Apr. 12, 1932 1,905,643 Johnson Apr. 25, 1933 1,907,943 Fitzpatrick May 9, 1933 2,422,168 Kirby June 10, 1947 2,468,265 Larquetoux Apr. 26, 1949 2,555,359 Montague June 5, 1951 2,687,017 Gerwick Aug. 24, 1954 2,772,539 Sandberg Dec. 4, 1956 2,857,744 Swiger Oct. 28, 1958 2,863,292 Coyne Dec. 9, 1958 2,941,369 Quirin June 21, 1960 2,963,178 Walker Dec. 6, 1960 2,973,046 McLean Feb. 28, 1961 2,995,900 Hunsucker Aug. 15, 1961 3,054,268 Muller Sept. 18, 1962

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