US3495658A

US3495658A - Underwater wellhead assembly

Info

Publication number: US3495658A
Application number: US742997*A
Authority: US
Inventors: Glenn D Johnson
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1968-05-29
Filing date: 1968-05-29
Publication date: 1970-02-17
Anticipated expiration: 1987-02-17

Description

if W, 19'10 G. D. JOHNSON UNDERWATER WELLHEAD ASSEMBLY Original Filed May 25, 1961 INVENTOR:

HTW

AGENT United States U.S. Cl. 166-.5 16 Claims ABSTRACT F THE DISCLSURE Underwater owline section for connecting a vertical flow conduit of an underwater wellhead with the vertical end of an underwater owline. The flowline section is releasably connected to the wellhead llow conduit and the ilow line by coupling that can be remotely actuated. The ilow line section can be removed from the wellhead and flow line by remotely controlled means. A swivel coupling in the flowline section permits the ow line section when uncoupled from the wellhead to swing horizontally from the wellhead to permit vertical entry of tools into the well.

This is a continuation of application Ser. No. 112,616, filed May 25, 1961, now abandoned.

This invention relates to offshore wells drilled in earth formations lying below a body of water, wherein the wellhead equipment of the well is positioned below the surface of the water, and pertains more particularly to a method and apparatus for installing and connecting, or disconnecting and removing, a fluid owline which normally carries well production fluid from the well.

Methods have recently been devised for drilling wells at offshore locations and placing the production wellhead equipment below the surface of a body of water and preferably on the ocean floor. The arrangement of a production wellhead assembly in this manner, i.e., on the ocean oor, reduces the navigation hazards over an offshore oil field and does away with the necessity of installing cumbersome and expensive steel platforms around a well casing to protect it from damage. However, underwater wellhead assembliespresent certain problems in doing maintenance work on the wells or the fluid owlines therefrom. For example, in the event that a fiuid flowline from a well becomes damaged, specially designed handling apparatus and methods must be employed to remove the damaged ilowlines and to install a new one.

It is therefore a primary object of the present invention to provide a method and apparatus for remotely removing a damaged owline from an underwater wellhead assembly and replacing it with another owline.

Another object of the present invention is to provide a atent C method and apparatus for lowering a llowline to the ocean floor, bringing it into alignment with a wellhead assembly positoined near the ocean oor and connecting it to the fluid discharge port from the casinghead.

A further object of the present invention is to provide an underwater well with a flowline therefrom extending upwardly and gently curving outwardly from the casinghead, the curve of said liowline being sufficient to permit circulation of well tools along the ocean floor and through the flowline to enter the top of the well casinghead.

A still further object of the present invention is to provide fiowline apparatus for an underwater wellhead adapted to be readily disconnected from the top of the well casinghead and moved to one side to permit vertical access into the well casinghead for well maintenance or other operations.

Still another object of the present invention is to provide a wellhead ilowline connection in the form of a U- bend section of ilowline releasably connected at one end of the top of a well casinghead and at the other end to a vertical section of the main flowline which subsequently runs along the ocean floor.

These and other objects of this invention will be understood from the following description taken with reference to the drawing: wherein,

FIGURE 1 is a diagrammatic view illustrating one form of the wellhead assembly of the present invention with a flowline connected thereto; and

FIGURE 2 is an isometric fragmental view of a portion of the support frame for a section of the flowline.

Referring to FIGURE 1 of the drawing, a wellhead assembly 11 is shown as being connected to a conductor pipe 12 which generally forms the outermost casing string of a well drilled in the ocean floor 13, or in a formation covered by a body of water. For purposes of illustration, the wellhead assembly 11 is shown as being positioned on the ocean floor 13. However, in many circumstances, for example, where the ocean floor is very muddy, it may be desirable to position the wellhead assembly 11 at some distance above the ocean oor 13 on the upper end of the conductor pipe 12.

In the foregoing description, the term welhead assembly is meant to include any assemblage of components either xedly or removably secured to the top of one or more strings of pipe extending into the ocean oor, either during the drilling, completion, production, reworking, or maintenance of a well. For purposes of illustrating the present invention, the top of the wellhead assembly 11 is shown as that of a producing well which generally includes such components as a casinghead 14, and adaptor 15 secured to the top of the casinghead, as by bolts 16, a master valve 17 anda coupling 18, all of the above recited elements being connected coaxially together and in coaxial relationship with the tubing and casing in the well. The valve 17 is provided with a valve handle or shaft 19 in the form of an outwardly-extending horizontally-movable element, preferably extending on a radial line of the wellhead assembly. The bolts 16 securing the adaptor 15 to the casinghead 14 and the bolts 20 for connecting the coupling 18 are also in the form of outwardly-extending horizontally-movable elements like the valve handle 19. A nut, preferably outwardly tapered for alignment purposes, is provided at the end of each

movable element

16, 19 and 20.

The coupling 18 may be of any suitable type with one portion thereof being secured to a nipple 22 mounted above the master valve 17, while the other portion of the coupling 18 is secured to a U-bend section 23 of a llowline which is connected at its other end by means of another coupling 24, preferably of the swivel type, lwhich in turn is connected to a preferably vertical section 25.

of the main llowline 26. The llowline section 25 is normally provided with a valve 27 having a Valve handle 28. In a like manner, the coupling 24, like the coupling 18, is provided with lock screws 29. If desired, a swivel joint 21 may be installed above coupling 24 so that it is not necessary to unbolt coupling 24 if the flowline section 23 is merely to be moved to one side.

Means are provided for lowering the curved section 23 of the owline 26 into place at the wellhead assembly,

either alone or when connected to the owline 26. In this particular arrangement of the apparatus, a series of bracing members 31, 32 and 33 are welded to the curved section 23 of the flowline at various points and are welded together at a slip ring 34 to which a guide and lowering line may be secured for lowering this section of owline to the ocean oor, as from a barge 35 on the ocean surface, in any suitable manner well known to the art. The vertical and

horizontal sections

25 and 26, respectively, of the flowline may be rigid or ilexible, but are preferablvflexible for ease of changing lines in deep water. When a flexible line 25-26 is employed, it is necessary to provide suitable support means, such for example as truss member 36 which is lixedly secured to the support platform 37 at the well base and extends upwardly therefrom. In the arrangement shown the truss member 36 is provided with a guide plate 40 (FIGURE 2) having an aligning notch 41 therein. The distance between the center of the aligning notch 41 and the axis of the casinghead 14 depends upon the precise measurements of the curved section 23 of the owline so that the

couplings

18 and 24 may be simultaneously in alignment. The support bar 42 is provided with a head 43 which prevents the bar 42 from slipping out of the notch 41.

The upper end of the truss member 36 may be provided with a support plate 44. The support plate 44 is preferably wide enough so that coupling 18 may be disconnected, allowing the curved section 23 of the flowline to be pivoted on its other end, in coupling 24, to one side of the casinghead 14 so that workover operations may be carried out from the barge 35 down through the top of the well. A curved section 23 of the flowline is necessary in order to carry out various minor well maintenance operations or tests by circulating tools from shore or from a production platform (not shown), through the

tlowline

26, 25 and 23 and thence downwardly through the well. Thus, the owline must be attached to the top of the well and curve upwardly and outwardly therefrom, generally through an arc of substantially 180 although this is not necessary at all installations. The

couplings

18 and 24 may be positioned on the salme horizontal plane or one may be positioned above the other, as desired.

Fixedly secured to the wellhead assembly 11 is a substantially horizontal track 45 on which a remotely controlled manipulator device 46 is mounted for movement in either direction around the track. If desired, a second track 47 is ixedly secured to the wellhead assembly 11 in spaced relationship with the track 45. Any desired spacial relationship of the tracks 4S and 47 may be employed. While the track 47 is shown as being spaced both vertically and horizontally away from track 45, with track 47 the higher of the two tracks, their positions could be reversed with the outer track 45 being the higher track, or both tracks being in the same horizontal plane with the manipulator device 46 riding on them or between them. Alternatively, the

tracks

47 and 45 may be of the same diameter while being spaced vertically with the manipulator device hanging from one or both of them. Preferably, the

tracks

45 and 47 extend entirely around the wellhead assembly 11 so that the manipulator device `46 may be positioned at any point on the circumference of the track to carry out operations on any component of the wellhead assembly or the owline thereof. For example, the manipulator device 46 is employed to operate

valve handles

19 and 28 of

valves

17 and 27, respectively, and to operate

bolts

20 and 29 of the

couplings

18 and 24, respectively.

A preferred form of the track-mounted manipulator device 46 is shown in FIGURE 1, although it is understood that the manipulator device may take any suitable form for carrying out the operations as described with regard to this invention. It is also to be understood that, when operating in shallow waters, the owline of the present invention may be connected and disconnected by divers. The manipulator device 46 is similar to that described in my copending application, Ser. No. 24,558, filed Apr. 25, 1960. The manipulator device 46 comprises a body section 50 having a vertical arm 51 extendible upwardly therefrom and rotatable on a vertical axis while having secured to the upper end thereof a horizontal arm element provided with a horizontallyextendible and/or rotatable head 53. In this particular arrangement the rotatable head 53 would be in the form of a wrench adapted to engage and rotate

screws

16, 19, 241 and 29 of the wellhead apparatus. If desired, a second horizontal arm (not shown) similar to arm 52 could be provided having a grappling hook or claws at the outwardly extending end thereof, as described in copending patent application Ser. No. 24,558, tiled Apr. 25, 1960i. The vertical arm 51 of the manipulator device 46 may be constructed to extend l() feet or more upwardly above the body member 50, depending upon the vertical height of the wellhead on which it is to be used.

A lowering cable 54 is secured to a sling element '55 which in turn is secured to the manipulator device for lowering the manipulator device through the water. In the event that the prime mover means (not shown) within the manipulator device 46 are electrically operated, the cable 54 may be a combined weight-bearing and powertransmission cable combined in one unit, or a second cable 56 may be employed. Alternatively, electric power and/or hydraulic fluid could be transmitted through a separate conduit or conduits into the manipulator device 46 for energizing the various elements of the manipulator device. The prime mover means, which may be of any suitable type, employed to rotate, extend and retract the various sections of the manipulator 4i), 50 including its

arms

51 and 52 with respect to each other, are contained within the manipulator device 46, or in a controller at the operating base above the surface of the water, or split between the two locations. Both the

arms

51 and 52 may be provided with telescoping sections to give added extension to the arms.

The body section 50 of the manipulator device 46 is provided with suitable guide means, for example,

wheels

57 and 58 for engaging upper and

lower tracks

45 and 47, respectively. The wheels 58 may serve as the weightcarrying wheels while the wheels 57 are merely the stabilizing wheels, or on the other hand the manipulator device 46 may hang from the upper wheels 57 while the lower wheels S8 are used as the stabilizing-wheels. If desired, a bumper 59 may be employed to hold the manipulator device 46 away from the wellhead assembly 11. To observe operations being carried out at the wellhead assembly 11 by the manipulator device 46, the manipulator device 46 is provided with one or more swivel mounted floodlights 63 and one or more television cameras 64, for lighting the area in the vicinity of the wellhead and observing operations, respectively. The television camera and lights may be tilted up or down or rotated from side-to-side either simultaneously with the wrench head 53, or independently thereof in order merely to observe operations. Both the lights 63 and the television camera 64 are remotely controlled by an operator positioned, say at the surface on the operating barge 35, the signal from the camera 64 being transmitted through the cable 56.

In replacing a damaged flowline to the well illustrated in FIGURE 1 the manipulator device 46 would be lowered from the barge 35 by means of cable 54 and positioned on the track or tracks 45 and 47 secured to the wellhead assembly 11. The vertical arm 51 of the manipulator device 46 would be extended upwardly and the telescoping end of the horizontal arm 52 extended outwardly until the wrench head 53 was adapted to engage the valve handle 19 of the master valve 17. The wrench head 53 would then be rotated to close the valve 17 The

arms

51 and 52 of the manipulator device 46 would then be positioned at a level to engage the bolts 20 of coupling 18, with the manipulator device 46y being moved around the

tracks

45 and 47 by power being supplied to one of the sets of

wheels

57 or 58. If desired at this time the coupling 24 at the other end of the curved section 23 of the owline may be uncoupled or it may be left coupled.

Prior to seating the manipulator device 46 on the

tracks

45 and 47, the manipulator device 46 may be used to carry a hook and cable 65 and 66 down from the barge 35 and attach it to the ring 34 so that after coupling 18 is disconnected the curved section 23 of the tlowline can be lifted oif the wellhead to the surface or may be dropped to the ocean oor. Thus the disconnected end of the flowline may be hoisted to the barge 35 by means of cable 66 or the

entire flowline

26, 25 and 23 may be removed from the vicinity of the well by pulling on the flowline from its other end. Another flowline would then be run into place along the ocean floor and lowered into place by means of cable 66 with the manipulator device 46 being employed to position accurately the portions of the couplings together and then secure them together by screwing their bolts into place. If desired, by disconnecting both

couplings

18 and 24 the curved section 23 of the flowline may be raised to the surface and replaced with another section. Alternatively, if the flowline is not damaged but it is merely desired to obtain entrance into the well, the manipulator device 46 could be employed to disconnect coupling 18 and move the disconnected end of curved section 23 to one side of the casinghead 14.

Thus, it may be seen with reference to the drawing and foregoing description that according to the present invention, well completion apparatus is provided wherein an underwater wellhead assembly having vertical iiuid passage means is disposed with the vertical axis thereof at a predetermined distance from a substantially vertical flowline section. Another fiowlne section having spaced apart ends is releasably connected between said underwater wellhead assembly and said substantially vertical iiowline section to provide iiuid communication there between.

l claim as my invention:

1. An underwater wellhead assembly comprising a well casinghead secured to and extending upwardly from the floor of a body of water, said casinghead having vertical fluid conduit means extending therethrough, closure means releasably secured to the top of said casinghead for closing the conduit means thereof, at least one fluid iiowline extending through said closure means and being in communication with at least one of said conduit means in said casinghead, a section of said fluid -owline being releasably secured to the top of said casinghead closure means and extending upwardly and gently curving outwardly therefrom, and coupling means carried on the outwardly-extending end of said curving iiowline section laterally displaced from said wellhead assembly, the end of the main section of said owline havingva vertically disposed axis and being iixedly positioned at a predetermined distance from the vertical axis of the wellhead assembly and adapted to be coupled at one end of said coupling means and extending to said ocean floor and then substantially horizontally therealong, the axis of both ends of said curved iiowline section being positioned substantially parallel to each other and being substantially vertical when connected on one side to said uid flowline extending to said casinghead closure means and on the other side to said coupling means.

2. An underwater wellhead assembly comprising a well casinghead secured to and extending upwardly from the floor of a body of water, said casinghead having vertical fluid conduit means extending therethrough, closure means releasably secured to the top of said casinghead for closing the conduit means thereof, at least one fluid flowline extending through said closure means and being in communciation with at least one of said conduit means in said casinghead, a section of said iiuid flowline being releasably secured to the top of said casinghead closure means and extending upwardly and gently curving outwardly therefrom, swivel coupling means carried on the outwardly-extending end of said curving flowline section laterally displaced from said wellhead assembly, the main section of said owline adapted to be coupled at one end to said coupling means and extending downwardly to said ocean floor and then substantially horizontally therealong, and manipulator means adapted to -be remotely controlled and being positionable adjacent said casinghead for locking said gently-curving section of ilowline in communication with said casinghead, said manipulator means including control cable means extending from `a remote location.

3. An underwater wellhead assembly comprising a well casinghead secured to and extending upwardly from the floor of a body of water, said casinghead having vertical fluid conduit means extending therethrough, closure means releasably secured to the top of said casinghead for closing the conduit means thereof, at least one fluid owline extending through said closure means and being in communication with at least one of said conduit means in said casinghead, a section of said iiuid flowline being releasably secured to the top of said casinghead closure rneans and extending upwardly and gently curving outwardly therefrom through an arc of substantially degrees, disconnectible swivel coupling means carried on the outwardlyextending end of said curving flowline section laterally displaced from said wellhead assembly, and a substantially vertical section of said iiowline adapted to be coupled at its upper end to said coupling means aud extending downwardly to said ocean floor and then substantially horizontally therealong.

4. An underwater wellhead assembly comprising a well casinghead secured to and extending upwardly from the iioor of a body of water, said casinghead having vertical liluid conduit means extending therethrough, closure means releasably secured to the top of said casinghead for closing the conduit means thereof, at least one uid flowline extending through said closure means and being in communication with at least one of said conduit means in said casinghead, a section of said uid iiowline being releasably secured to the top of said casinghead closure means and extending upwardly and gently curving outwardly therefrom through an arc of substantially 180 degrees, disconnectible swivel coupling means carried on the outwardly-extending end of said curving owline section laterally displaced from said wellhead assembly, a substantially vertical section of said iiowline adapted to be coupled at its upper end to said coupling means and extending downwardly to said ocean floor and then substantially horizontally therealong, support means positioned adjacent said wellhead for supporting said gentlycurving section of flowline in both its connected and disconnected positions.

5. An underwater wellhead assembly comprising a well casinghead secured to and extending upwardly from the iioor of a body of water, said casinghead having vertical uid conduit means extending therethrough, closure means releasably secured to the top of said casinghead for closing the conduit means thereof, at least one iiuid flowline extending through said closure means and being in communication with at least one of said conduit means in said Icasinghead closure means, a section of said fluid flowline being releasably secured to the top of said casinghead and extending upwardly and gently curving outwardly therefrom through an arc of substantially 180 degrees, disconnectible swivel coupling means carried on the outwardly-extending end of said curving fiowline section laterally displaced from said wellhead assembly, a substantially vertical section of said iiowline adapted to be coupled at its upper end to said coupling means and extending downwardly to said ocean oor and then substantially horizontally therealong, support means adjacent said wellhead for supporting said gently-curving section of flowline, track means mounted on said wellhead assembly, and manipulator means positionable on said track means for locking said gently-curving section of iiowline in communication with said casinghead, said manipulator means including control cable means extending from a remote location.

6. An underwater wellhead assembly comprising a casinghead secured to and extending upwardly from the floor of a body of water, said casinghead having vertical fluid passage means extending therethrough, closure means releasably secured to the top of said casinghead for closing the passage means thereof, a fluid flowline having a first section and a second section and means mechanically connecting one end of said first section to the top of the closure means, said first section of the fiuid flowline extending upwardly and gently curving from said closure means, coupling means carried on the other end of said first section of the iiuid fiowline and laterally displaced from said casinghead, said second section of the iiuid fiowline having an end portion with a substantially vertically disposed axis, means fixedly positioning said end portion substantially vertically and at a predetermined distance offset from the vertical axis of the casinghead, said end portion being releasably coupled to said coupling means, said second section of flowline extending downwardly to the floor of said body of water and then laterally therealong, the axes of the ends of said first section of fluid iiowline being substantially parallel to each other and being substantially vertical when connected at one end to said closure means and at the other end to said second section of the flowline through said coupling means.

7. An underwater wellhead assembly comprising a casinghead secured to and extending upwardly from the fioor of a body of water, said casinghead having vertical fluid passage means extending therethrough, closure means releasably secured to the top of said casinghead for closing the passage means thereof, a fiuid fiowline having a first section and a second section and means mechanically connecting one end of said first section to the top of the `closure means, said first section of the fiuid flowline extending upwardly and gently curving from said closure means, pipe coupling means having first and second connectible mating portions, said first portion of said coupling means carried on the other end of said first section of the fiuid fiowline and laterally displaced from said casinghead, said second section of the fiuid fiowline having an end portion with a substantially vertically disposed axis and being provided with said second lmating portion of said coupling means, the coupling end of said second section of flowline being fixedly positioned substantially vertically and at a predetermined distance offset from the vertical axis of the casinghead, said end portion being releasably coupled by said coupling means, said second section of flowline extending downwardly to the oor of said body of water and then laterally therealong, the axes of the ends of said first section of fluid fiowline being substantially vertical when connected at one end to said closure means and at the other end to said second section of the fiowline through said coupling means.

8. An underwater wellhead assembly comprising a casinghead secured to and extending upwardly from the fioor of a body of water, said casinghead having vertical fluid passage means extending therethrough, closure means releasably secured to the top of said casinghead for closing the passage means thereof, a fluid flowline having a first section and a second section and means mechanically connecting one end of said first section to the top of the closure means, said first section of the fluid flowline extending upwardly and then outwardly from said one end of said first section of fiowline connected to said closure means with the other end of said first section of owline being directed downwardly, pipe coupling means having first and second connectible .mating portions, said first portion of said coupling means carried on the other end of said first section of the fluid flowline and laterally displaced from said casinghead, said second section of the fluid flowline having an end portion with a substantially vertically disposed axis and being provided with said second mating portion of said coupling means, the coupling end of said second section of iiowline being fixedly positioned substantially vertically and at a predetermined distance offset from the vertical axis of the casinghead, said end portion being releasably coupled by said coupling means, said second section of fiowline extending downwardly to the floor of said body of water and then laterally therealong, the axes of the ends of said first section of -uld flowline being substantially vertical when connected at one end to said closure means and at the other end to said second section of the flowline through said coupling means.

9. Well completion apparatus of the character defined in claim 8, including means mounting the flowline on the base for removal therefrom.

10. Well completion apparatus, comprising an underwater wellhead including a base and a Christmas tree remotely mounted on the base in an upright position, a fiowline having an upwardly-directed end near the wellhead which extends substantially parallel to the vertical axis of the Christmas tree, means including a U-tube releasably connectable to the Christmas tree and the end of the flowline for fiuid communication therebetween, and actuatable means for connecting and releasing the opposite ends of said means with respect to said Christmas tree and end of the fiowline.

11. Well completion apparatus of the character defined in claim 10, incl-uding means mounting said end of the owline in an upright position on the wellhead base.

12. Well completion apparatus of the character defined in claim 10, including means mounting said U-tube on the base with its opposite ends in an upright position.

13. Well completion apparatus, comprising an underwater wellhead including a base and a Christmas tree removably :mounted on the base and having a vertically extending flow passage, a fiowline having a vertically extending end substantially adjacent and laterally offset from the Christmas tree and extending substantially parallel to said lChristmas tree, means including a U-tube releasably connected to the Christmas tree and the end of the flowline to provide fluid communication between said fiowline and the iiow passage in the Christmas tree, and means responsive to remote actuation for so connecting and releasing the opposite ends of said means with respect to each of said Christmas tree and flowline end.

14. Well completion apparatus of the character defined in claim 13, wherein the end of the flowline faces upwardly and the ends of the U-tube face downwardly and releasably connect with the upper end of the Christmas tree and said end of the fiowline to permit said U-tube to be removed upwardly therefrom.

15. Well completion apparatus, comprising an underwater wellhead including a base and a Christmas tree on the base, a flowline having an end near the wellhead, means including connectors having movable locking parts for releasably connecting said Christmas tree and end of the fiowline to provide fluid communication therebetween, and means opera-ble from a remote location for lowering said connectors into and raising them from connecting positions with respect to said `Christmas tree and end of the fiowline and moving said locking parts between locking and unlocking position when said connectors are in connecting position.

16. Well completion apparatus, comprising an underwater wellhead including a base and a Christmas tree on the base, a owline having an end near the wellhead, tubular means releasably connectible to the Christmas tree and end of the flowline to provide fluid communication therebetween, connectors having movable locking parts for releasably connecting the tubular means to each of said Christmas tree and end of the flowline, and means operable from a remote location for lowering said con- 9 l0 nectors into and raising them from connecting positions 3,090,437 5/ 1963 Geer 166-.6 X with respect to said Christmas tree and end of the flowline 3,177,942 4/ 1965 Haeber 166-.5 and moving said locking parts between locking and un- 3,195,638 7/1965 Le Rouax 166-.5 locking position when Said connectors are in connecting 3,202,216 8/ 1965 Watts et al. n 166-.6 p0siti0n- 5 3,353,364 11/1967 Blanding et al 166-.5` X

delle ces ite CHARLES E OCONNELL P E 1E P TE T ry Xa ner UNITED STA S A N S rima m1 2,810,442 10/1957 Tausch n 166m5 X RICHARD E. FAVREAU, Asslstant .Examlner 2,840,166 6/1958 Eckel etal. 166--.5 X l0 U5, C1. X R 3,022,822 2/1962 McStravick et al. 166-.5 X 175-7