US3202217A

US3202217A - Submarine cellar for deep water drilling operations

Info

Publication number: US3202217A
Application number: US138523A
Authority: US
Inventors: John D Watts; Slack John
Original assignee: Gray Tool Co
Current assignee: Vetco Gray LLC
Priority date: 1961-09-15
Filing date: 1961-09-15
Publication date: 1965-08-24
Anticipated expiration: 1982-08-24

Description

1965 J. D. WATTS ETAL 3,202,217

SUBMARINE CELLAR FOR DEEP WATER DRILLING OPERATIONS i E 7 u F? Y ii 32 /\J I 36 5 2 1 s 7 A 1 s) k 48 so 42 A 26 INVENTORS A 28 30 Jowvfl 14 his ATTORNEYS Aug. 24, 1965 J. D. WATTS ETAL SUBMARINE CELLAR FOR DEEP WATER DRILLING OPERATIONS Filed Sept. 15, 1961 4 Sheets-Sheet 2 W m m/ m w 9 1 F 2 I s w v flu 8 H m -IIIH G 1-1 I a m m H M \w w w A mm? w m m EMA 6 H a I 8 m e w 17 w a 3 Z a M M m a v 0 avw A .1 N x M P N w a .w. w m ,ww w

l ll LJ ATTORNEYS 1965 J. D. WATTS ETAL 3,202,217

SUBMARINE CELLAR FOR DEEP WATER DRILLING OPERATIONS Filed Sept. 15, 1961 4 Sheets-Sheet 3 4% BBQZYIYI 92 W so} fno I 1 78 h I06 INVENTOR LIOB JOHN-D. fl -S MW @M 6W ATTORNEYS Aug. 24, 1965 J. D. WATTS ETAL 3,202,217

SUBMARINE CELLAR FOR DEEP WATER DRILLING OPERATIONS Filed Sept. 15, 1961 4 Sheets-Sheet 4 FIGJI.

[/ 1 3!]: LELZO INVENTORS (/Ol-l/V 2 h/fl T ATTORNEY? United States Patent 3,2tl2,2l7 SUBMARINE CELLAR FOR DEEP WATER DRELLING OPERATIONS Jclm D. Watts and .lohn Slack, Houston, Tex, assignors to Gray Tool Company, Houston, Tex, a corporatien of Texas Filed Sept. 15, 1961, Ser. No. 138,523 17 Claims. (Cl. 166-46) This application is a continuation-in-part of application Serial No. 785,984, filed January 9, 1959. The invention relates to underwater drilling operations in which a portable submersible chamber, or submarine cellar, is mounted on the upper end of a pipe set into the bottom and in particular to improvements in the construction of the submarine cellar, in the structure and method for supporting the cellar and the pipe in their underwater positions and in the method of conducting drilling and other well-forming operations with the aid of these structures,

In drilling offshore oil wells, it is often customary to set a relatively large diameter pipe, often referred to as a drive pipe, vertically into the submerged bottom and to conduct subsequent drilling operations andthe landing of the casings and tubing through the drive pipe which extends upwardly to above the surface of the water. The drive pipe may be, for example, two feet or more in diameter and is driven into the bottom by any suitable driving mechanism. Conventionally, after the drilling operation has been completed and the casing run in and cemented, the drive pipe is cut off at some distance below the water surface and the well head comprising various control equipment, casing heads and oil production line to the surface are mounted on the top of the remaining portion of the drive pipe. Various methods for the attachment of these elements have been used including the use of divers and the use of a variety of water tight housings submersible to engagement with the top of the drive pipe and adapted to accommodate men and equipment for making the necessary connections. After completion of the well head, the chamber would be removed, leaving the well head below the surface and suitably marked with a buoy.

Application Serial No. 785,984 discloses a tapered type of fitting on the upper end of a drive pipe and a particular type of submersible chamber for workmen having an aperture in the bottom wall adapted to engage the fitting in water tight relationship whereby the interior of the chamber is communicable with the interior of the drive pipe. The top wall of the chamber is provided with several rigid access pipes extending to above the surface, one of which is coaxial with the aperture in the bottom wall whereby the drill string and the various casings can be lowered therethrough as needed. When the well head is to be completed, the well head control equipment is lowered through one of the access pipes and workmen in the chamber make the necessary connections. After the workmen have returned to the surface through one of the access pipes, the chamber with attached access pipes is removed from the fitting on the drive pipe and may be used in the construction of another well or may be refitted, when necessary, to the top of the drive pipe for making adjustments to the well head equipment.

The present invention provides an improved construction for the housing, or water cellar, which permits drilling operations to be more easily conducted through the cellar and drive pipe. More in particular, the improved cellar construction embodies a telescopic stack extending upwardly from the housing in axial alignment with the bore of the drive pipe and connectable in its retracted position with the top of the fitting whereby the telescopic stack can be placed in communication with the drive pipe. When the stack is extended upwardly, its upper end extends above the surface of the water and control equipment use during drilling operations, such as blowout preventers and mud lines, can be easily attached thereto and a drill string can be easily inserted therethrough. When the stack, carrying this control equipment, is lowered to engagement with the top of the fitting, the control equipment becomes submerged. In the event of a storm, the drill string can be removed, and the stack, carrying the control equipment, can be submerged to a depth sufiicient to protect it from wave action and to present no navigation hazard.

The present invention also provide an improved construction for the drive pipe and fitting which permits a long string of drive pipe, extending upwardly from the bottom, to be maintained straight without the use of a complicated and expensive building platform. At the same time, the improved construction relieves compressive stresses in the drive pipe resulting from its own weight and from the weight of additional structures which may be fixed to the top of the pipe during construction of the well. These advantages are attained by providing the drive pipe and fitting with a buoyancy tank of controlled buoyancy whereby variable lifting force may be applied to the drive pipe and fitting.

It is therefore a primary object of the present invention to provide a novel and improved submersible chamber through and from which offshore drilling and well-comp etion operations may be performed.

It is a further object of the present invention to provide a novel and improved submersible chamber for use in offshore well-forming operations which has a telescopic stack adapted to be releasably connected to a sub merged well head at one end inside the housing and to be extensible upwardly from the housing.

It is a further object to provide a novel and improved apparatus for use in offshore well-forming operations including a submerged housing; a drive pipe set in a submerged bottom and extending upwardly therefrom a considerable distance for supporting the housing from below, and a telescopic stack extensible upwardly from the housing whereby the upper end of the stack is above the surface when extended and submerged when retracted.

It is a still further object to provide novel and improved means for buoyantly supporting and maintaining straight the above-mentioned drive pipe.

It is a still further object to provide a novel and improved method for conducting offshore drilling and wellcompletion operations.

The invention will be better understood from a reading of the following detailed description taken in conjunction with the drawings in which:

FIGURE 1 is an elevational sectional view of a submarine water cellar embodying the principles of the present invention taken on the line 1-1 of FIGURE 2 and on an enlarged scale;

FIGURE 2 is a top plan view of the submarine water cellar of FIGURE 1;

FIGURE 3 is an elevational view, partly in section, of a drive pipe and support base for a submarine cellar;

FIGURE 4 is an elevational view illustrating the manner in which the water cellar of FIGURE 1 may be floated to location;

FIGURES 5 and 6 are elevational views illustrating the lowering of the water cellar onto the support base of FIGURE 3;

FIGURE 7 is an elevational view illustrating the Water cellar when first secured to the support base;

FIGURE 8 is an elevational view illustrating the water cellar with its stacks extended into the well of a drilling ship preparatory to the attachment of equipment to the stacks;

FIGURE 9 is an elevational view, partly in section, illustrating the retracted position of the telescopic drilling stack and its attachment to the support base during drilling operations;

FIGURE illustrates the storm positions of the telescopic stacks and associated equipment wherein the water cellar is temporarily abandoned leaving all attached equiprnent below water level;

FIGURE 11 illustrates the completion of the well after drilling has been completed and after the casings and tubing have been landed; and

FIGURE 12 is an elevational view, partly in section, showing a modified cellar support base and drive pipe.

Referring to FIGURES 1 and 2, there is shown a generally cylindrical submarine water cellar 10, constructed in accordance with the principles of the present invention and defining a chamber 12 which when pumped clear of water is adapted to receive workmen and equipment. As shown, the cellar 10 is integrally constructed of a cylindrical side wall 14, a downwardly tapered bottom wall 16 and a top wall 17. The top wall 17 is provided with a plurality, two as shown, of upwardly extending, tubular stacks 18, integral with or otherwise rigidly secured to the top wall and communicating with the chamber. In accordance with the invention, each of these

fixed stacks

18 and 20 is provided with an inner,

slidable telescoping stack

22 and 24, respectively, and suitable leak-preventing seals therebetween. The bottom wall 16 is provided with a relatively large aperture and an upwardly tapered conical passage 26 communicating with the chamber. The wall 28 of the passage 26 is adapted to mate with the upwardly tapered surface of the support bases of FIGURES 3 and 12. Sealing rings 30 are preferably provided in suitable annular grooves in the wall 28 to aid in obtaining a water-tight fit between the cellar and its base.

. More in particular, the cellar includes an inner cylindrical vertical wall 32 which forms the side wall of the compartment 12 and which defines an annular buoyancy chamber 34 with the cellar side wall 14. A plurality of spaced horizontal reinforcing members 36 extend between the

walls

14 and 32 and are secured thereto in any suitable manner. The buoyancy chamber 34 is provided with a line 38 adapted to be connected to a source of compressed air, a seacock 40 operable by remote means to place the chamber 34 in communication with ambient water and a check valve 42 for preventing ambient water from entering the buoyancy chamber while permitting water in the chamber to be expelled by compressed air delivered by the line 38. Passing vertically through the top wall 17, the buoyancy chamber 34 and the bottom wall 16 are two diametrically positioned guide tubes 44 for receiving cables or guide bars during lowering or raising the cellar. The guide tubes 44 are open at both ends and are secured and sealed to the top and bottom walls as by welding.

. The chamber 12 is preferably provided with a sump 46 and sump pump 48 located at the bottom thereof for maintaining the chamber free of water during the time that workmen are present therein by pumping water from the sump through an outlet 50 in the bottom wall. Above the sump and pump is a horizontal platform 52, preferably of grid-like construction, on which workmen may stand. The platform 52 extends radially outwardly from the upper end of the wall 28 to the inner circumference of wall 32 whereby a well head which is being constructed with the use of the apparatus may extend upwardly into the chamber 12 through the passage 26.

As is evident from FIGURES 1 and 2, the pair of

stacks

20, 24 is in axial alignment with the central basereceiving passage 26. The telescoping stack 24 may conveniently be a smooth-walled seamless casing having outwardly extending

flanges

54, 56 at its upper and lower ends, respectively. The length of stack 24 is preferably such that, in its fully retracted position, its lower end is somewhat above the top of the passage-defining wall 28.

As shown in FIGURE 1, the lower end of stack 24 is provided with a clamp-type connector 58 which connects the stack with a short flanged extension 60 by clamping the flanges of the stack and extension to a sealing ring 62 inserted between the flanges. This type of connection is more fully described in Patent No. 2,766,829 and may be used wherever a releasable, pressure-tight connection between lengths of tubing or casing is desired. The lower end of the extension, as shown at 64- is exteriorly threaded for screwing into a support base. The exterior of the central telescoping stack 24 is provided with an integral annular ring 66 which slidably fits the inner surface of the central fixed stack 20 so as to maintain the stacks coaxial. Suitable packing material 68 is provided in an annular groove in the ring so as to form a seal between the two stacks. stack 24 as to remain within the outer stack 20 even in the fully retracted position of the inner stack thereby providing its alignment and sealing functions at all relative positions of the stacks during operation.

The upper end of outer stack 20 is provided with a relatively thick-walled section 69 having an inwardly extending integral ring 70 through which the inner stack slides. Packing material 68 in an annular groove in the ring effects a second seal between the stacks. A check-valve 71 is provided in the wall of the stack just below section 69 to permit any air in the annulus between the

stacks

20 and 24 to be expelled during upward movement of stack 2

Stacks

18 and 22 are laterally oifset from passage 26 and are constructed in the same manner as the stacks 2t and 24. Telescopic stack 22 has an upper flange 72 and is provided at its lower end with an external integral ring '73. The top of fixed stack 18 is provided with a thickwalled section 74 having an internal integral ring 75. Packing material as in an annular groove in each

ring

73, 75 effects a seal between the stacks. A check-valve 76 permits air to be expelled from the annulus between the stacks during upward movement of stack 22. Telescopic stack 22, which in FIGURE 1 is shown in the fully extended position, may be somewhat shorter than the central telescopic stack 24 because stack 22 need not extend to the platform 52 when in the retracted position. The two fixed

stacks

18, 20 may be secured against relative lateral movement near their outer ends by a plate 77 which surrounds each stack and which is rigidly secured thereto as by welding.

While the actual dimensions of a submarine water cellar constructed as above described are not part of the present invention, it is contemplated that a practical cellar would have a diameter and height of about twenty feet and that the fixed

stacks

18, 20 would have a length of about forty-five feet and a diameter of about thirty inches.

The telescoping stacks 22, 24 would be extensible about forty-five feet whereby the cellar chamber 12 can be maintained in communication with the atmosphere through the stacks while being submerged about one hundred feet below the surface of a body of water. The smallest diameter of the tapered passage 26 should exceed the diameter of any well head equipment to be used so that the cellar may be withdrawn upwardly from a completed well head.

It should be understood that the cellar described above and illustrated in the drawings is subject to many modifications and refinements within the scope of the invention. For example, the working chamber may be provided with electric lights, a hoist movable along an elevated track and various means for locking the cellar to its base support. Reference is made to application Serial No. 785,- 984 for a full description of several embodiments of submarine cellars of the type suitable for use in the present invention. All or any of the details shown therein which are not incompatible with the use of upwardly extending telescoping stacks are contemplated by the present invention.

FIGURE 3 illustrates 'a buoyant type of support base 78 suitable for releasably supporting the water cellar 14 from a submerged bottom 36. In this figure, the base 73 V is shown connected to the upper end of a drive pipe 82 set The ring 66 is so located on the inner in the submerged bottom and to the lower end of an extension pipe 84 extending to above the surface 86. The extension pipe 84- is used in the setting of the drive pipe 82 and base 78 in the bottom and is removed before the cellar 19 is mounted on the base. An important feature of the base 78 is fully described in application Serial No. 785,984 is the upwardly and inwardly tapering fitting 88 which is adapted to mate with the tapered wall 28 of the cellar so as to form a releasable water tight joint therewith. Another important feature is the arrangement of the fitting 88 on the upper end of the drive pipe 82 such that the interior of the drive pipe will communicate with the cellar chamber 12 when the cellar is mounted on the fitting.

In accordance with the present invention, an additional feature is the provision of a controlled buoyancy tank 90 for the base 78 for the purpose of supporting some of the weight of the drive pipe 82 and some of the weight of additional equipment when mounted on the fitting 88, and for maintaining the drive pipe 82 substantially straight.

As shown in FIGURE 3, the fitting 88 of the base illustrated therein has the general shape of a truncated cone and is provided with an axial bore 92 open at both ends for communication with other structures. As disclosed in application Serial No. 785,984, there are numerous modifications of the fitting 88 which may be included as desired or needed. For example, the fitting should be adapted to be releasably locked to the cellar in water-tight relationship. This may be accomplished, as fully disclosed in said application, by providing suitable annular surfaces as at M on the fitting 88 for receiving remotely controlled locking pins -95 which may be slidably retained in the tapered wall 2 8 of the cellar 10. Alternatively, the top of the fitting may be externally threaded and a locking ring (not shown) provided, which when screwed onto the fitting after the cellar has been mounted thereon will clamp the tapered wall 28 to the fitting 83. Additionally, the bore 92 of the fitting may be internally threaded at both ends, as shown, for attachment to other structures, or the threads may be omitted and the other structures welded to the ends of the fitting as needed. Preferably, the fitting 83 will include a second, smaller bore 96 extending from the top to the side at a location below the cellar 10 for connecting with a line g8 which leads to the surface 86. After the well has been completed through the drive pipe 82, the upper end of the bore 96 will be connected to the well head assembly by workmen in the cellar chamber 12 for carrying oil from the well head to a storage container (not shown) at the surface.

The base 78 illustrated in FIGURE 3 includes an annular buoyancy tank 90 mounted below the fitting 88 as with bolts me which pass through an annular flange 102 on the lower end of the fitting 88 and into the top of the tank 9%. The drive pipe 82 passes axially through the buoyancy tank 9ft in Water-tight relationship and threadedly engages the lower end of the bore 92, of the fitting. The tank may be secured to the fitting, the drive pipe or both, it being necessary only to make the tank unitary with, or fixed with respect to, the pipe 82.

The tank 9% is provided with any suitable means for controlling its buoyancy from the surface, such as a com pressed air line 1634, seacock 16d and check-valve 108 and suitable controls (not shown) therefor for adjusting the amount of water within the tank. The top of the tank is provided with two diametrically spaced cellar guide posts 119 which are pivoted for movement toward and away from the axis of the fitting by means of suitable pins 112 and lugs 114 secured to the peripheral edge of the tank top. The cellar guide posts 11% are of such spacing and length as to be insertable through the guide tubes 44 of the cellar 1d of FIGURE 1 for the purpose of guiding the cellar 18 onto the base 78. As seen in FIGURE 3, the base 73 is shown in a position awaiting arrival of the cellar 1t and its position marked by a 6 buoy 1'16 attached by cables 18 to the upper ends of the guide posts 110. As indicated before, the extension pipe 84 will be removed from the top of the fitting 88 before the cellar 10 is lowered onto the fitting.

The placing of the drive pipe 82 and base 78 in the positions shown in FIGURE 3 may be accomplished in any conventional manner from, for example, a drilling ship. Conveniently, the lengths of extension pipe 84a, lengths of drive pipe 82a and the base 78 may be taken to the well side, assembled there and lowered by suitable cables and hoists (not shown) until the lower end of the drive pipe sinks into the bottom 86. The assembly may be carried out in steps as the drive pipe 82 is lowered through the water, or all the elements may be assembled initially and the completed unit lowered. Driving of the drive pipe 82 to the desired depth into the bottom may be effected by driving its upper end or the upper end of the extension pipe 84 or by providing water jets {not shown) and suitable lines and controls (not shown) therefor on the lower end of the drive pipe 82.

Although the particular length of extension pipe 84 and drive pipe 82 form no part of the invention, the present invention is particularly adapt-ed for use with bottoms which may be, for example, 600 feet below the surface. Since it may be desirable to operate the cellar at approximately 100 feet below the surface, the drive pipe 82 will extend, in this situation, about 500 feet above the bottom and the extension pipe 84 will extend approximately 100 feet from the base 7 8 to above the surface 86. After the base 78 and drive pipe 82 have been secured to the bottom by driving the drive pipe into the bottom a suitable distance, the extension pipe 84 is unscrewed from the top of the base 78 or otherwise removed if a threaded connection has not been provided between the two.

When a great length of drive pipe has been used, it will be desirable to reduce the compressive forces in the drive pipe which result from its own weight. In the construction of the present invention, this may be accomplished by opening the seaco-ck 106 and connecting line Hi4 to a source of compressed air (not shown) at the surface and thereby blowing out .sorne of the water 120 in the buoyancy tank through the seacock. The tank 9% in becoming more buoyant tends to lift the base 78 which, being secured to the top of the drive pipe 82, tends to lift the drive pipe. Additionally, if the lengths 84a of extension pipe 84 are added sequentially as the base 78 and drive pipe 82 are being lowered during the initial steps, the buoyancy of the tank 90 may be increased at intervals to aid in supporting the weight of the pipes 82., 84 and base 78. In this event, when the drive pipe 82 reaches the bottom, the buoyancy of the tank 90 may be temporarily decreased by releasing the air pressure and opening the seacock 106 so as to allow the drive pipe 82 to penetrate the bottom as a result of the combined weight of pipes and bases.

The steps of mounting the cellar 10 on the base 78 of FIGURE 3 are illustrated in FIGURES 4-7. In FIG- URE 4, the cellar 10, with

inner stacks

22, 24 retracted for convenience, is shown being towed by a ship 122 to a well site. The cellar 10 may be secured to the towing ship 122 in any convenient manner as by lines 124 attached to the ship as at 126, run through the guid tubes 44 in the cellar and attached to the top wail of the cellar as at 128. In FIGURE 5, the cellar 1G is shown being sunk onto the base 7 8, from which the extension pipe 84 has been removed, by controllab'ly filling the cellar buoyancy tank 34 with water from air and seacock controls 129 on the ship. The lines 124, now connected at their lower ends to the upper ends of the guide posts on the base, serve to guide the cellar 10 in the desired path toward the base.

FIGURE 6 illustrates the cellar 10 axially aligned with the base 78 by means of the lines 124 and submerged by additional filling of the cellar buoyancy tank 34 so as to telescope the guide tubes 44 over the guide posts 119. FIGURE 7 illustrates the final lowering of the cellar onto the base whereby compression of the sealing rings 30 by the Weight of the cellar effects a water-tight seal between the fitting 88 and tapered wall 28 of the cellar. If a remote control latch arrangement has been provided between fitting and cellar, it may now be activated to lock the two together.

After the cellar has been landed and latched, the buoyancy of tanks 34 and 9t) ofthe cellar and base, respectively, can be adjusted to relieve some of the load from the drive pipe 32. Normally, the cellar will be maintained sufficiently non-buoyant to maintain a water-tight seal between it and the fitting. Later, as various casings (FIGURES 10 and 11) are landed within the drive pipe and hung from the top of the fitting 88, the buoyancy of the base buoyancy tank fitl may be increased, as necessary, to support the added weight thereby relieving the drive pipe 32 from additional compression.

In order to conduct operations from or through the seated cellar 1d, the

telescopic stacks

22, 24 will be first extended'upwardly to above the surface 86, as seen in FIGURE 8, and the chamber 12 pumped free of Water by any suitable means, such as by the sump pump 48 or by a separate line (not shown) connecting with a pump (not shown) at the surface. The drive pipe 82 will normally be pumped free of water at this time also. The

stacks

22, 24 may be extended, lowered or held in any intermediate position by any suitable means such as cables (not shown) attached to the upper ends of the stacks and operated by suitable hoists (not shown) at the surface. In FIGURE 8, the

stacks

22, 24 are shown as having been extended upwardly into the drilling well 130 of a conventional drilling ship 132 preparatory to the attachment of drilling equipment to the center stack 24. The upper end of the offset stack 22 normally will remain open to the atmosphere for the lowering of men and equipment therethrough and for carrying air and electrical conduits as needed.

Check-

valves

71 and 76 in the fixed stacks allow flow only in an outward direction. Thus, water is substantially prevented from entering the annuli between concentric stacks and any water or air which does become trapped in the annuli is ejected through the check valves during upward movement of the telescopic stacks. The creation of a vacuum in the annuli during downward movement of the telescopic stacks has no significant elTect on the buoyancy of the apparatus because of the large weight of the cellar and stacks.

To begin drilling operations, the center telescopic stack 24, while extended above water in the drilling well 130 of the ship 132 is provided at its upper end with appropriate connections and blowout preventers. The stack 24 is then lowered, as seen in FIGURE 9, until the lower end of its threaded extension member 60 engages the top of the fitting 88 into which it may be screwed, by workmen in chamber 12, to place the stack 24 in direct communication with bore 92 of the fitting 38. Appropriate equipment attached to the upper end of stack 24 will normally include blowout preventers 134 and other control equipment 136 connected to each other and to the flanged top of the stack 24 by clamp-type connectors 138. Above the

control equipment

134 and 136 and connected thereto by a flexible ball joint 144i is an extension 14-2 of suitable length to extend into the drilling well 130 of the ship after the stack 24 has been lowered. Conveniently, the extension 1 2 may be made up lengths of casing connected sequentially to each other as necessary, as the stack 24 and

connected equipment

134, 136 is lowered to the position of FIGURE 9. Since the extension 142 is positioned above the blowout preventers, it need not withstand high pressures and accordingly may be of relatively light-weight construction. If desired, the extension 142 may be of flexible construction.

After the connection between the stack 24 and the fitting ?ifi has been completed, the buoyancy of the base buoyancy tank 9h may be increased to support the weight 0 of the added equipment. A conventional drill string 144,- including a bit 146 at its lower end, is then inserted through the extension 142,

control equipment

134, 136, stack 24, fitting 88 and finally the drive pipe 32. Conventional drilling of a hole in the bottom axially with the drive pipe 82 may then be commenced with the aid of suitable conventional equipment, such as a rotary table, draw works, Kelly joint, etc. (not shown) located on the drilling ship 132.

One of the advantages of the

telescopic stacks

22, 24 associated with the cellar iii lies in the ease with which the cellar can be temporarily and safely abandoned during interruptions of the drilling operations resulting from storms or other causes. In the event that a storm arises while drilling is in progress, the drill string 144 will be withdrawn and the extension 142 removed from above the blowout preventers 13 i and other control equipment 1%. The upper end of the control equipment and the upper end of the offset telescopic stack 22 may then be suitably capped as at 148 and the

stacks

22, 24 telescoped downwardly so as to completely submerge all structure which is attached to the cellar.

FIGURE 10 illustrates the cellar temporarily abandoned in the storm position after some of the Wellforming steps have been effected. As shown, a string of protection casing 15%) has been run through the drive pipe 82 and cemented in a conventional manner. Also a conventional casing head 1552 and casing head spool 154 have been installed by workmen in the chamber 12 between the lower end of the center telescopic stack 24 and the upper end of the extension ea which previously has been screwed into the fitting 83. The entire cellar 1t) and associated structure is thus maintained below water a sufficient distance, for example 30 feet, to be unaffected by wave action and to present no hazard to navigation. A marking buoy (not shown) will ordinarily be attached to the cellar to indicate the location of the apparatus.

Upon return of the drilling ship 13?. to the location, the telescopic stacks 22 and 2,4- are raised into the drilling well 134 to again provide access for men and equipment and to receive the extension 142 and drill string 144. Drilling operations and the landing of casing 156 and tubing 158, as needed, may then be completed through the extension 142, stack 24 and drive pipe 82 in a conventional manner. Conventional equipment required for casing heads and the tubing head will be lowered through the otfset pair of

stacks

18, 22 and will be installed, as needed, at the top of the fitting by workmen in the cellar chamber. As indicated above, the buoyancy of the base 78 may be continually increased during these operations to carry the added weight.

After the production tubing 15% has been installed, the center telescoping stack 24 will be disconnected from the well head and drawn upwardly so that the blowout preventers 134 and other equipment 136 can be removed from the upper end thereof above the surface by men on the drilling ship 132. Conventional well-completion equipment including a Christmas tree arrangement 16-:- can then be lowered through stacks 13, 22 and installed on the wall head by workmen in the chamber 12.

FIGURE 11 illustrates the well head in the final stages of completion. As shown, the protective casing 1150, production casing 156 and tubing 158 have been installed in the drive pipe 82 and a conventional Christmas tree 164 has been installed on the various casing heads. A line 166 has been connected between the Christmas tree 164- and the offset bore 96 in the fitting 83 whereby oil produced by the well may be delivered to the surface through the line 98. A section of a Christmas tree protector 168 is shown being lowered through the offset stacks 18, 22 by means of a cable 178. This and other sections will then be secured in place around the Christmas tree by workmen to complete the operations performed inside the cellar.

The men will then return to the surface through the stacks, the telescoping stacks 22, 24 will be retracted into the fixed stacks 18, 29 and the cellar will be unlatched from the base 78 by operation of the latch controls (not shown) at the surface. The cellar buoyancy chamber 34 will be emptied of water by blowing in compressed air whereby the cellar will rise to the surface under the guidance of the guide lines illustrated in FIGURES 47. The cellar may then be towed to another well-site and employed as above described as it may be lowered onto an existing well head and base for making adjustments to the well head equipment. The completed well head and base shown in FIGURE ll, being well below the surface, present no navigation hazard and are unaffected by wave action. Normally, the position of the well will be indicated by a buoy as shown in FIGURE 3. Upon abandonment of the well, the well-head and base 78 may be left in position, or some of the equipment may be reclaimed with the aid of the cellar.

FIGURE 12 illustrates a modified cellar support base 75 which may be advantageously used in deep water. As has been discussed above, the portion of the drive pipe extending above a submerged bottom is subjected to high compressive forces due to its own weight and to the weight of the inner casings which are hung from the casing heads just above the fitting. In order to relieve the drive pipe of some of this stress, the drive pipe 32' in the FIGURE 12 arrangement has been provided with a vertically elongated annular buoyancy chamber 172. The chamber is formed by providing an outer axial pipe 174 which is spaced from and coextensive with a substantial portion of that part of the drive pipe 82 which projects from the bottom. As shown, the upper end of the outer pipe 1'74 is rigidly secured to the lower surface of the fitting 88 as by welding, and its lower end is rigidly secured to the drive pipe 82 as by providing an inwardly extending portion 176 and welding same to the periphery of the drive pipe 32, communicating with the annular chamber 172 near the upper end thereof through the outer pipe 174 is a compressed air line 173 leading to a suitable compressed air source 18%) and controls 182 at the surface 86. Near the lower end of the chamber 172 is an aperture 184 through the outer pipe for the passage of water into and out of the chamber. An extension pipe 34' analogous to extension pipe $4 extends from the top of fitting 33' to above the surface 86'.

The inner and outer pipes 32', 172 and the fitting may be assembled ashore and transported to the site as a uni tary structure, or assembly of the parts may be made sequentially at the site as the drive pipe 82 is being lowered toward the bottom. In either case, the respective lengths of each pipe, $271 and 174m, may be joined to each other in any suitable manner as by welding or by means of threaded connections. The diameter and length of the outer pipe relative to the inner pipe may vary considerably depending on the desired buoyancy.

The operation of the elongated annular buoyancy tank 172 is similar to that of the base buoyancy chamber 99 already described except that the elongated tank 172, being secured to the drive pipe 82' at two vertically spaced locations, applies its lifting force at these two locations. The base buoyancy tank 99 applies all of its lifting force only to the top of the drive pipe. The elongated tank 172 thus has the advantage of applying some lifting force directly at the lower portion of the drive pipe 82' where the compressive forces would otherwise be highest. As in the operation of the base buoyancy tank 99 described above, the elongated buoyancy tank 172 will be blown free of more and more water as the additional weight of inner casings is applied to the fitting 88'.

It will thus be appreciated that the construction of the water cellar and support base in accordance with the principles of the present invention provide apparatus having great utility in the drilling and completion of wells in deeply submerged bottoms. The base is readily secured to bottoms of different depths and is adapted by means of its variable buoyancy to support a large range of weights without unduly compressing the drive pipe. The use of telescoping stacks in combination with the cellar while permitting drilling operations to be readily carried out from the surface, provides for simple interruption of drilling without danger of storm damage to the well head.

The above description is intended to be illustrative of the invention and the details therein are not intended to be limiting except as they appear in the appended claims.

What is claimed is:

1. A method of conducting offshore drilling and wellforming operations comprising: driving pipe of relatively large diameter substantially vertically into a submerged bottom whereby the upper end of said pipe is below the surface; providing a housing defining a chamber for workmen and having an upwardly extending telescopic tubular member communicating with said chamber and an aperture coaxial with said member; releasably mounting said housing on the upper end of said pipe; sealing said housing to said pipe in water-tight relationship whereby said pipe communicates with said chamber through said aperture; raising said telescopic member whereby its upper end projects above the surface; attaching drilling control equipment to the upper end of said member; inserting drilling means through said equipment into said member; lowering said member into sealing relationship with the upper end of said pipe; and conducting drilling operations through said member and said pipe.

2. A method as in claim 1 further comprising: relieving compressive forces in said pipe and maintaining said pipe vertical by providing a buoyancy tank fixed with respect to said pipe and by adjusting the buoyancy of said tank in accordance with the length of said pipe.

3. A method as in claim 1 further comprising: establishing a well head at the upper end of said. pipe within said chamber; and relieving compressive forces in said pipe due to the additional weight of said well head by providing a buoyancy tank fixed with respect to said pipe and by adjusting the buoyancy of said tank in accordance with the magnitude of the weight of said well head.

4. A method as in claim 1 further comprising: establishing a well head at the upper end of said pipe within said chamber and between said upper end of said pipe and the lower end of said telescopic member; disconnecting said telescopic member from said well head and extending said member upwardly away from said well head; completing said well head with well head completion equipment from within said chamber; and releasing and removing said housing from the upper end of said pipe whereby said completed well head remains submerged and supported from the bottom by said pipe.

5. Apparatus for conducting underwater drilling operations comprising: pipe means of relatively large diamcter driven into a submerged bottom, the upper end of said pipe means being below the surface of the water; a housing of sufiicient size to contain men and having a passageway in the bottom thereof, the wall of said passageway being relcasably secured to the top of said pipe means in watertight relationship, said housing having an upwardly extending telescopic tubular member coaxial with said passageway and communicating through its lower end with the interior of said housing, the upper end of said telescopic member being above the surface of the water when said telescopic member is fully extended and below the surface of the water when said telescopic member is fully retracted; and control equipment mounted on the upper end of said telescopic member whereby drilling operations may be carried out through said telescopic member and whereby such operations may be shut down rapidly and safely by ceasing drilling and lowering said telescopic member with the control equipment attached below the surface of the water.

6. A submersible housing of a size to contain men comprising: means including top, bottom and side walls il l defining a chamber, said bottom wall being provided with a generally vertical passage; an elongated upwardly extending telescopic tubular member carried by said housing, said telescopic member being disposed coaxially above said passage and terminating at its lower end within said chamber and at its upper end outside said housing, said telescopic member being extensible from and retractable into said chamber and having a smaller transverse cross section than said chamber so that there is sutficient space for men between said telescopic member and said side wall of said chamber when said member is retracted into said chamber; means for preventing leakage of fluids past the exterior surface of said telescopic member into said chamber; well control equipment mounted coaxially on top of said telescopic member; and fluid conduit connecting means mounted coaxially on the lower end of said telescopic member.

7. A submersible housing as in claim d including means separate from said telescopic member for providing access to said chamber for men and equipment, said means including an elongated upwardly extending member carried by said housing in oifset relationship to said telescopic member.

8. Apparatus for use in underwater drilling and well completion operations comprising: pipe means having its lower end embedded in a submerged bottom and an open upper end below water level at a considerable distance above the submerged bottom, said pipe means including a fitting at its upper end; said fitting having an internal bore extending completely therethrough and an exposed annular surface, a circumferential portion of which is inclined outwardly and downwardly to define a sealing surface for receiving a removable housing, said bore having a substantially uniform diameter which is substantially the same as the diameter of said pipe, said fitting having a passageway therethrough in addition to said bore, said passageway extending from above said sealing surface to below said sealing surface whereby well fluids may be conducted through said fitting; a buoyancy tank fixed to said pipe means and disposed below said sealing surface; and means to adjust the buoyancy of said tank whereby controllable lifting force may be applied to said pipe means.

9. Apparatus for use in underwater drilling and Well completion operations comprising: pipe means having its lower end embedded in a submerged bottom and an upper end below water level, said pipe means including a fitting at its upper end, said fitting having an internal bore extending completely therethrough and an exposed annular seating surface; a submersible housing of a size to contain men having a wall defining a downwardly facing aperture, said wall being in complementary watertight releasable engagement with said seating surface, said fitting and housing thereby defining a chamber which is in communication with said bore; a vertically extending telescopic tubular member carried by said housing, said telescopic member being disposed coaxially above said aperture and said bore and terminating at its lower end within said chamber and at its upper end outside said housing, said telescopic member being extensible from said housing to a position in which its upper end is above water level and retractable into said chamber to a position in which its lower end is engageable with the upper end of said bore, the transverse cross section of said telescopic member being substantially smaller than the transverse cross section of said chamber so that there is sufiicient space for men in said chamber when said telescopic member is retracted into said chamber; and complementary fluid-tight releasable connecting means carried at the lower end of said telescopic member and at the upper end of said bore for releasably connecting said telescopic member to said bore whereby drilling operations may be carried out through said telescopic member, said bore and said pipe means and whereby manual operations may be carried out at the upper end 12 of said bore from within said chamber when said telescopic member is disengaged from said bore.

10. Apparatus as in claim 9 wherein said housing carries a tubular member offset from said telescopic member and extending from said chamber to above water level for providing access for men and equipment.

11. Apparatus as in claim it} wherein said offset tubular member is telescopic and is retractable into said housing to a position in which its upper end is below water level and wherein the upper end of said first-mentioned telescopic member is below water level when the same is in its retracted position.

12. Underwater apparatus for use in conjunction with a mobile submersible housing extending to above water level and of a size to contain men, said apparatus comprising: pipe means having its lower end embedded in a submerged bottom and an upper end below water level at a location a substantial distance above the submerged bottom, said pipe means including a fitting at its upper end, said fitting having an internal bore extending, completely therethrough and an exposed frusto-conical seating surface which tapers inwardly and upwardly; a well head assembly sealed to the top of and supported by said fitting at a position wholly above said seating surface, the maximum horizontal dimension of said assembly being less than the minimum horizontal dimension of said frusto-conical seating surface; well fluid tubing extending through said pipe means and said bore and suspended at its upper end from said well head assembly; a sealed annular buoyancy tank surrounding and fixed to said pipe means at a location below said frusto-conical seating surface; and mean for controlling the buoyancy of said tank.

13. Apparatus as in claim 12, wherein said buoyancy tank is of restricted horizontal cross section and is coextensive with substantially the entire length of said pipe means, said tank being fixedly secured to said pipe means only near the upper and lower ends thereof whereby lifting force is applied to the upper portion and to the lower portion of said pipe means.

14. A method of conducting underwater well forming operations comprising: lowering a vertically disposed pipe structure through a body of water to'a posit-ion at which the upper end remains above water; sealing an annular buoyancy tank of controllable buoyancy around said pipe structure at least at the upper end thereof; sequentially connecting sections of pipe to the above-water end of the pipe structure above said buoyancy tank and further lowering the pipe structure into said body of water to completely submerge said tank; increasing the buoyancy of said tank as said pipe structure is lowered; subsequently decreasing the buoyancy of said tank in order to increase the effective weight of said pipe structure; embedding the lower end of said pipe structure into the submerged bottom; removing said pipe sections from above said tank; releasably attaching a removable housing of a size to contain men around the top of said pipe structure, said housing extending to above water level; drilling downwardly through said housing and through said pipe structure into the submerged bottom; constructing and suppcrtin a well head assembly on top of said pipe structure at a location above said tank; and releasing and removing said housing from the top of said pipe structure.

15. A method as in claim 14 in which said pipe structure is constructed by connecting lengths of pipe to the upper end of said structure as the same is lowered through the body of water and wherein said buoyancy tank is constructed by providing .an outer concentric pipe section at the lower end of said pipe structure, sealing the lower end of said outer section to the exterior of said pipe structure, connecting additional sections to the lowermost outer section as said pipe structure is lowered; and sealing the upper end of the uppermost section to the exterior of said pipe structure.

16. A method of constructing a submerged well head assembly comprising lowering a vertically disposed pi e structure into a body of Water; sealing an annular buoyancy tank of controlled buoyancy around said pipe structure at least at the upper end thereof; further lowering said pipe structure to sub-merge said tank; embedding the lower end of said pipe structure in the submerged bottom; releasably attaching a removable housing of a size to contain men around the top of said pipe structure, said housing extending to above water level; drilling downwardly through said housing and through said pipe structure into the submerged bottom; constructing and supporting a well head assembly on top of said pipe structure at a location above said buoyancy tank, said constructing and supporting operations including sequentially running casing and tubing strings downwardly through said pipe structure and suspending them from said assembly; and in creasing the buoyancy of said tank each time a string is suspended from said assembly; and releasing and removing said housing from the top of said pipe structure.

17. A method as in claim 16 in which said pipe structure is constructed by connecting lengths of pipe to the upper end of said structure as the same is lowered through the body of Water and wherein said buoyancy tank is constructed by providing an outer concentric pipe section 14 at the lower end of said pipe structure, sealing the lower end of said outer section to the exterior of said pipe structure, connecting additional sections to the lowermost outer section as said pipe structure is lowered; and sealing the upper end of the uppermost section to the exterior of said pipe structure.

References Cited by the Examiner UNITED STATES PATENTS 597,597 1/98 Webb 61-82 1,785,582 12/30 OROuTke 61-69.1 2,187,871 1/40 Voorhees 2- 16666.5 2,348,777 4/44 Bessire 114l6.7 2,476,309 7/49 Lange 175-8 2,512,783 6/50 Tucker 1758 X 2,684,575 7/54 Pryor et a1. 1758 XR 2,783,970 3/57 Gillespie 175-8 XR 2,906,500 9/59 Knapp eta] 61-82 XR 3,017,934 1/62 Rhodes et a1 166-66.5 XR 3,101,798 8/63 Wilson et al. 1758 CHARLES E. OCONNELL, Primary Examiner.

Claims

14. A METHOD OF CONDUCTING UNDERWATER WELL FORMING OPERATIONS COMPRISING: LOWERING A VERTICALLY DISPOSED PIPE STRUCTURE THROUGH A BODY OF WATER TO A POSITION AT WHICH THE UPPER END REMAINS ABOVE WATER; SEALING AN ANNULAR BUOYANCY TANK OF CONTROLLABLE BUOYANCY AROUND SAID PIPE STRUCTURE AT LEAST AT THE UPPER END THEREOF; SEQUENTIALLY CONNECTING SECTIONS OF PIPE TO THE ABOVE-WATER END OF THE PIPE STRUCTURE ABOVE SAID BUOYANCY TANK AND FURTHER LOWERING THE PIPE STRUCTURE INTO SAID BODY OF WATER TO COMPLETELY SUBMERGE SAID TANK; INCREASING THE BUOYANCY OF SAID TANK AS SAID PIPE STRUCTURE IS LOWERED; SUBSEQUENTLY DECREASING THE BUOYANCY OF SAID TANK IN ORDER TO INCREASE THE EFFECTIVE WEIGHT OF SAID PIPE STRUCTURE; EMBEEDING THE LOWER END OF SAID PIPE STRUCTURE INTO THE SUBMERGED BOTTOM; REMOVING SAID PIPE SECTIONS FREOM ABOVE SAID TANK; RELEASABLY ATTACHING A REMOVABLE HOUSING OF A SIZE TO CONTAIN MEN AROUND THE TOP OF SAID PIPE STRUCTURE, SAID HOUSING EXTENDING TO ABOVE WATER LEVLE; DRILLING DOWN-