US3602301A

US3602301A - Underwater borehole servicing system

Info

Publication number: US3602301A
Application number: US853371A
Authority: US
Inventors: Theodore K James
Original assignee: Transworld Drilling Co
Current assignee: Transworld Drilling Co
Priority date: 1969-08-27
Filing date: 1969-08-27
Publication date: 1971-08-31
Anticipated expiration: 1988-08-31

Abstract

Underwater borehole servicing system in which a submersible chamber is pulled down onto a wellhead platform by a hauldown cable. In one embodiment, accurate alignment of the chamber with the platform is effected by extensible guide projections on the chamber cooperating with receiving recesses on the platform. In another embodiment, an annular, depending portion of the chamber cooperates with an annular guide segment of a generally hemispherical platform to align the chamber on the platform. In a third embodiment, alignment is effected by a combination of extensible guide projections on the chamber and an annular chamber portion respectively cooperating with recesses and an annular guide segment on the platform. Propulsion devices carried by the chamber are provided for registering the aligning equipment on the chamber with the aligning equipment on the platform.

Description

United States Patent Primary Examiner-Ian A. Calvert Assistant Examiner-Richard E. Favreau Auarney-Shanley and ONeil ABSTRACT: Underwater borehole servicing system in which a submersible chamber is pulled down onto a wellhead platform by a hauldown cable. In one embodiment, accurate alignment of the chamber with the platform is effected by extensible guide projections on the chamber cooperating with receiving recesses on the platform. In another embodiment, an annular, depending portion of the chamber cooperates with an annular guide segment of a generally hemispherical platform to align the chamber on the platform. In a third embodiment, alignment is effected by a combination of extensible guide projections on the chamber and an annular chamber portion respectively cooperating with recesses and an annular guide segment on the platform. Propulsion devices carried by the chamber are provided for registering the aligning equipment on the chamber with the aligning equipment on the platform.

ATEHTED M1831 I971 3.602.301

INVENTOR msonom; K. JAMES ATTORNEYS BY umvs UNDERWATER BOREHOLE SERVICING SYSTEM BACKGROUND OF THE INVENTION This invention pertains to systems for servicing underwater boreholes. More particularly, the invention relates to methods and apparatus for servicing submarine wellheads.

It has been proposed to service underwater wellheads by hauling a servicing chamber down to he wellhead assembly. However, prior art systems are disadvantageous in that it is difficult to effect accurate registration of the servicing chamber with the wellhead assembly. Accordingly, a main object of the invention is the provision of improved underwater borehole servicing systems in which accurate alignment of the servicing chamber with the wellhead assembly is quickly and easily effected.

Other objects and advantages of the invention will appear from the following detailed description which, with the accompanying schematic drawings, discloses three embodiments of the invention for purposes of illustration only and not for determining the limits of the invention. For defining the scope of the invention, reference will be made to the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of underwater wellhead servicing apparatus embodying principles of the invention.

FIG. 2 is a view on section line 2-2 of FIG. 1.

FIG. 3 depicts the structure of FIG. 1 with the servicing chamber seated on the wellhead platform.

. FIG. 4 illustrates the hydraulic system for operating the extensible guide projections of the structure of FIG. 1.

FIG. 5 is a side view of another underwater wellhead servicing apparatus embodying principles of the invention.

FIG. 6 is a cross-sectional view on line 6-6 of FIG. 5

FIG. 7 is a side view of a third underwater wellhead servicing apparatus embodying principles of the invention.

Primed and double-primed reference numerals denote elements similar to the elements indicated by the unprimed numerals.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS In FIG. 1, a submersible chamber 10 is shown being hauled down for uniting with an underwater wellhead assembly 12 supported on ocean floor 14. The wellhead assembly includes a platform or base 16 which is carried by a concrete support 18 and surrounds well 20. The wellhead is indicated at 22.

Chamber 10 includes a hemispherical top wall 24 and continuous cylindrical sidewalls 26. The chamber is open at the bottom, and the lower edges of sidewalls 26 carry an annular sealing gasket 28. A deck 30 divides chamber 10 into upper and

lower compartments

32, 34 respectively. Communication between upper and lower compartments is provided by a hatch (not shown) sealed by a closure so that upper chamber 32 is watertight. Portholes 34 are provided in top wall 24 for vision by personnel in upper compartment 32. Portholes can also be provided in deck 30.

Beams 36, 38 (see also FIG. 2) are mounted on chamber sidewalls 26, and span lower compartment 34. A platform 40 carried by the beams supports a winch 42 which is powered by an electric motor 44. An elongated, flexible tension member in the form of a hauldown cable 46 is wound on winch 42, one end of the cable being connected to the winch and the other end being connected to the center of wellhead 22. Operation of winch 42 by motor 44 to reel in cable 46 hauls chamber 10 downwardly toward platform I6.

Aligning devices are carried by the chamber and by the platform and cooperate with one another to effect proper orientation of chamber 10 on platform 16. Thus, chamber 10 carries four guide projections in the form of

hydraulic cylinder assemblies

48, 50, 52, and 54 which are spaced around the periphery of the chamber. Each guide projection is selectively individually extensible and retractable. Each guide projection is similar to the others, so detailed description of one imparts an understanding of all. For example, guide projection 48 is mounted on a plate 56 which is secured to chamber sidewalls 26, and is braced by supporting framework not shown, Plate 56 carries a housing 58 which encloses elements of a hydraulic system for extending and retracting guide projection 48. The hydraulic system is illustrated in FIG. 4, where guide projection 48 is shown as comprising a hydraulic cylinder 60 which telescopically receives a piston rod 62 attached to a piston 64. Hydraulic fluid is forced from a reservoir 66 by a pump 68 through a hydraulic fluid supply line 70 to a three-way valve 72. With valve 72 in the central position shown, hydraulic fluid flowing in supply line 70 returns directly to reservoir 66 through a return conduit 74 and piston 64 is locked in position in cylinder 60. Shifting valve 72 to the right communicates supply line 70 with conduit 76, and communicates return conduit 74 with conduit 78. Hydraulic fluid flows into the upper end of cylinder 60 and extends piston rod 62, with hydraulic fluid in the bottom end of the cylinder bleeding through conduit 78 and return conduit 74. Moving the valve to the left from the central position communicates hydraulic fluid supply line 70 with conduit 78, and communicates return conduit 74 with conduit 76. Hydraulic fluid is conducted to the bottom of cylinder 60 through line 78 and moves piston 64 upwardly, retracting piston rod 62. Hydraulic fluid in the upper portion of the cylinder bleeds through conduit 76 and conduit 74 back to reservoir 66.

Each guide projection mates with one of four upstanding tubular receivers 80 which are spaced around the periphery of platform 16. Each receiver includes an upper, frustoconical entry portion 82 which guides the lower end of a guide projection into the central recess or aperture 83 of the receiver. The lower ends of the guide projections are rounded to facilitate their movement down the walls of entry portions 82.

Chamber 10 has a generally upright axis 84 and winch 42 is disposed adjacent the axis so that hauldown cable 46 is positioned at the general location of the axis. To effect lateral movement of the chamber, i.e., movement which is in a direction which is transverse to the upright chamber axis and is translational along the ocean floor and/or rotational around the chamber axis, chamber 10 carries four propulsion devices or thrusters 85. Each thruster 85 includes a screw propeller 86 powered by an electric motor 88. y

Thrusters 85 are spaced at intervals circumferentially around chamber axis 84. The thrusters can be selectively individually swiveled to thrust in any desired direction to move chamber 10 translationally along the ocean floor and/or rotationally about the chamber axis. The swivel mounting structure for each thruster 85 includes a pair of brackets 87, 89 which are secured to chamber sidewalls 26 and respectively rotatably receive

coaxial stub shafts

98, 91. The stub shafts are rigidly secured to motor 88, which pivots about the upright axis defined by the stub shafts when shaft 90 is rotated by an electric motor-speed reducer assembly 92 which is carried by bracket 87 and geared to shaft 90.

Operation of thrusters 85 is controlled from inside upper compartment 32, and by selectively swiveling the propulsion devices in their mountings to thrust in desired directions, chamber 10 can be translationally propelled in any desired direction and/or can be rotated in clockwise or counterclockwise direction relative to axis 84. It will be appreciated that more or fewer than four thrusters can be provided.

In use, well 20 is bored and wellhead assembly 12 constructed in any suitable, conventional manner. Hauldown cable 46 is attached to wellhead 22 and carried to the surface of the water. The location of the free upper end of cable 46 is attached to wellhead 22 and carried upper end of cable 46 is attached to a marker buoy (not shown). When it is desired to work at the wellhead for maintenance, repair or other purpose, the upper end of hauldown cable 46 is detached from the buoy and attached to winch 42 of chamber 10, which is brought to the site by a tender vessel. Workmen enter watertight compartment 32, which is sealed behind them. The chamber is lowered into the water with all guide projections held in retracted position. Water enters and floods lower compartments 34. When the lower compartment is flooded, chamber 10 has a slight positive buoyancy. Chamber 10 is released from the tender, and winch 42 is operated to shorten hauldown cable 46 by reeling the cable onto the winch. Shortening the cable pulls chamber 10 downwardly toward the wellhead assembly and completely submerges the chamber. Reeling in of cable 46 is continued, and the chamber is progressively pulled downwardly towards the wellhead to a location contiguous to the wellhead assembly, where the retracted guide projections just clear the receivers 80 as shown in FIG. I. The guide projection which is closest to a receiver is then partially extended. Chance may have it that this guide projection is already in registration with a receiver, whereupon the partially extended projection is fully extended to insert the extended projection into the receiver and winch 42 can be operated to further lower chamber 10 for the purpose of insertion. However, if no guide projection is in alignment with a receiver, registration of one guide projection with a receiver can be effected quickly and easily by operation of thrusters 85 to move chamber 10 translationally and/or rotationally as required to bring the parts into registration. Once the partially extended guide projection is aligned with a receiver, the projection is fully extended and inserted into the aligned receiver.

Once the extended projection is inserted into the receiver, thrusters 85 are operated to laterally propel the chamber, swinging it around the upright axis of the extended guide projection, to register the remainder of the guide projection, with the remainder of the receivers, and if desired the remaining guide projections can be partially extended to facilitate this operation. When the remaining guide projections are aligned with the receivers, the projections are fully extended into the receivers and winch 42 is operated to further shorten the cable until chamber 10 is firmly seated on platform 16. Because of the reception of the guide projections into the receivers, seating will be effected with the chamber in perfect alignment relative to platform 16. A watertight seal is effected between platform 16 and chamber 10 by annular gasket 28. As the chamber approaches seating on the platform, the guide projections are retracted, the piston rods being telescopically received in the cylinders to permit the chamber to seat on the platform.

After the chamber is seated, lower compartment 34 is pumped dry and workmen descend to service the wellhead. If desired, suitable clamps can be provided to clamp the chamber to the working platform, and tension on hauldown cable 46 can then be released. When work at the wellhead is completed, the men release the clamps, retire to the upper compartment and flood the lower compartment. Hauldown cable 46 is reeled out, and chamber 10 rises to the surface of the water.

The embodiment of the invention shown in FIG. 5 is similar to that of FIGS. 1-4, but employs another form of structure for aligning the servicing chamber with the wellhead platform. In FIG. 5, platform 16' is bowl-shaped having the general configuration of a hollow hemisphere, and includes an annular guide segment 94 having the general configuration of a frustum of the hemisphere. An outwardly turned peripheral guide lip 96 is formed on platform 16' and joins with guide segment 94. An annular ring 98 is supported on platform 16' for seating chamber A flat working floor 100 surrounds wellhead 22' and is supported by platform 16' and by a portion 102 of wellhead assembly 12.

In use, chamber 10' is hauled down from the surface of the body of water by reeling in hauldown cable 46' on which 42, as described hereinabove. When chamber I0 is at a location contiguous to platform 16', thrusters 85' are operated so that the chamber is laterally propelled to a location where the depending lower annular end portions of chamber sidewalls 26 downwardly for accurate disposition on seating ring 98 as the cable is reeled in to seat the chamber on the ring.

The embodiment of the invention shown in FIG. 7 is similar to that of the two preceding embodiments, but employs a combination of the aligning devices employed in those embodiments. In FIG. 7, chamber 10" carries a plurality of extensible guide projections, e.g. 48", which cooperate with tubular receivers on platform 16" in the fashion described hereinabove in connection with FIGS. l4. The annular lower portion of chamber 10" also cooperates with guide lip 96 and guide projection 94 of bowl-shaped platform 16" as previously described in connection with FIGS. 5-6.

In use, chamber 10 is hauled down and thrusters are operated to bring the chamber within the outline of guide lip 96". The chamber is pulled down within the confines of the platform and the sloping guide lip and annular guide segment 94" cooperate with the lower edge of the chamber to guide the chamber toward a centered position on the platform. One of the guide projections is then extended, registered with and then inserted into a receiver 80" as described hereinabove. The remaining guide projections are then registered and inserted into the remaining receivers, and chamber 10" hauled down onto seating ring 98".

I claim:

1. Method for uniting a submersible chamber and an underwater borehole assembly including a base and being connected to the chamber by an elongated tension member,

the chamber including first aligning means and the base including second aligning means,

the chamber including propulsion means for propelling the chamber,

one of the aligning means including a plurality of extensible and retractable guide projections and the other aligning means including means forming a plurality of recesses for receiving the guide projections,

comprising the steps of retracting the guide projections,

hauling the chamber down to a location contiguous to the base by shortening the tension member,

at least partially extending one of the guide projections,

propelling the chamber to register the one guide projection with a recess,

inserting the one guide projection into the registered recess,

propelling the chamber to register the remainder of the guide projections with the remainder of the recess, extending the remainder of the guide projections,

inserting the remainder of the guide projections into the registered recesses and,

hauling the chamber downwardly onto the base by further shortening the tension member.

2. Apparatus for submarine operations, comprising:

means defining a submersible chamber,

an underwater borehole assembly including a base,

cooperating first aligning means carried by the chamber on the base,

propulsion means carried by the chamber for propelling the chamber to register the first aligning means with the second aligning means, and

hauldown means including an elongated, flexible tension member connected to the chamber and to the underwater borehole assembly for hauling the chamber downwardly onto the base,

one of the aligning means including a plurality of extensible guide projections, and

means for selectively extending each guide projection, and

the other aligning means including means defining a plurality of recesses for receiving the guide projections.

3. The apparatus of claim 2, the first aligning means-including the guide projections and the second aligning means including the recesses.

4. The apparatus of claim 2,

the first aligning means including an annular, downwardly projecting guide member, and

the second aligning means including an annular guide member having the general configuration of frustum of a hollow hemisphere.

5. The apparatus of claim 2, the propulsion means being operable for propelling the chamber in translational and rotational movement.

6. The apparatus of claim 5,

the propulsion means including a plurality of propulsion members,

each propulsion member having a direction of thrust, and

directional means for changing the direction of thrust of each propulsion member.

7. The apparatus of claim 6, the directional means including means for moving each propulsion member to change the direction of thrust.

8. The apparatus of claim 6, each propulsion member including a screw propeller.

9. Apparatus for submarine operations, comprising:

means defining a submersible chamber,

an underwater bore hole assembly including a base,

cooperating first aligning means carried by the chamber and second aligning means carried by the base for aligning the chamber on the base,

the second aligning means including an annular guide member having the general configuration of a frustum of a hollow hemisphere.

10. The apparatus of claim 9, the second-named annular guide member having a flaring peripheral guide lip.

11. The apparatus of claim 9;

the base having the general configuration of a hollow hemi sphere, and

the second-named member forming a portion of the base.

12. The apparatus of claim 9, the propulsion means being operable for propelling the chamber in translational and rotational movement.

13. The apparatus of claim 12,

the propulsion means including a plurality of propulsion members,

each propulsion member having a direction of thrust, and

14. The apparatus of claim 13, the directional means including means for moving each propulsion member to change the direction of thrust.

15. The apparatus of claim 13, each propulsion member including a screw propeller.

3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,602,301 Da ed August 31, 1971 InVentQr 3) Theodore K. James It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 5 of "Background of the Invention", "he" should read -the--,

Column 2, line 64, before "clockwise" insert -a-;

line "71, cancel "attached to wellhead 22 and carried upper end of cable 46 is".

Column 3, lines 4 and 5, "compartments" should read -compar'tment-;

line 33, -projection, should read --.-projections-;

line '61, after "bowl-shaped" insert a comma line 71, "which" should read --winch-.

Column 4, line 18, "94' should read -94"-;

line 52, "recess" should read -recesses-; line'62, after "chamber" insert --and second aligning meanscarried by the base for aligning the chamber-,.

Column 5, line 8, after "of" (first occurrence) insert line 26, "bore hole" should read --borehole--.

Column 6, line 16,, before "member" insert *'-annular guide-.

Signed and sealed this lhth day of 'March 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting; Officer ROBERT GOTTSCHALK Commissioner of Patents

Claims

1. Method for uniting a submersible chamber and an underwater borehole assembly including a base and being connected to the chamber by an elongated tension member, the chamber including first aligning means and the base including second aligning means, the chamber including propulsion means for propelling the chamber, one of the aligning means including a plurality of extensible and retractabLe guide projections and the other aligning means including means forming a plurality of recesses for receiving the guide projections, comprising the steps of retracting the guide projections, hauling the chamber down to a location contiguous to the base by shortening the tension member, at least partially extending one of the guide projections, propelling the chamber to register the one guide projection with a recess, inserting the one guide projection into the registered recess, propelling the chamber to register the remainder of the guide projections with the remainder of the recess, extending the remainder of the guide projections, inserting the remainder of the guide projections into the registered recesses and, hauling the chamber downwardly onto the base by further shortening the tension member.

2. Apparatus for submarine operations, comprising: means defining a submersible chamber, an underwater borehole assembly including a base, cooperating first aligning means carried by the chamber on the base, propulsion means carried by the chamber for propelling the chamber to register the first aligning means with the second aligning means, and hauldown means including an elongated, flexible tension member connected to the chamber and to the underwater borehole assembly for hauling the chamber downwardly onto the base, one of the aligning means including a plurality of extensible guide projections, and means for selectively extending each guide projection, and the other aligning means including means defining a plurality of recesses for receiving the guide projections.

3. The apparatus of claim 2, the first aligning means including the guide projections and the second aligning means including the recesses.

4. The apparatus of claim 2, the first aligning means including an annular, downwardly projecting guide member, and the second aligning means including an annular guide member having the general configuration of frustum of a hollow hemisphere.

6. The apparatus of claim 5, the propulsion means including a plurality of propulsion members, each propulsion member having a direction of thrust, and directional means for changing the direction of thrust of each propulsion member.

9. Apparatus for submarine operations, comprising: means defining a submersible chamber, an underwater bore hole assembly including a base, cooperating first aligning means carried by the chamber and second aligning means carried by the base for aligning the chamber on the base, propulsion means carried by the chamber for propelling the chamber to register the first aligning means with the second aligning means, and hauldown means including an elongated, flexible tension member connected to the chamber and to the underwater borehole assembly for hauling the chamber downwardly onto the base, the first aligning means including an annular, downwardly projecting guide member, and the second aligning means including an annular guide member having the general configuration of a frustum of a hollow hemisphere.

11. The apparatus of claim 9; the base having the general configuration of a hollow hemisphere, and the second-named member forming a portion of the base.

13. The apparatus of claim 12, the propulsion means inclUding a plurality of propulsion members, each propulsion member having a direction of thrust, and directional means for changing the direction of thrust of each propulsion member.