US3316984A - Well apparatus - Google Patents

Description

M. R. JONES WELL APPARATUS May 2, 1967 2 Sheets-Sheet l Filed Nov. 20, 1964 IIIIIl JM H. m V m May 2, 1967 M. R. JONES 3,316,984

WELL APPARATUS Filed Nov. 20, 1964 2 Sheets-Sheet B Marv/f7 draf/@5 l NVENTOR.

ATTO/PNE VJ United States Patent Texas Fiied Nov. 20, 1964, Ser. No. 412,758 6 Claims. (Cl. 175-7) This invention relates generally to apparatus for use in drilling and/or completing an oil or gas well at an underwater level. More particularly, it relates to apparatus of this type having an improved system for guiding drilling and/vor completion equipment between a vessel at water level and the wellhead to which such equipment is adapted to be connected.

For example, in the drilling of a well of this type, a blowout preventer is lowered and connected onto the upper end of a casiiig head iixed to a base at the underwater level, whereby pressure control may be maintained over the well as the various casings are lowered into the `well through the head. Upon completion of the drilling operation, the blowout preventer is removed and replaced by a .so-called Christmas tree which connects to the head to maintain control over the well during its production.

In either case, some means must lbe provided for guiding such equipment between a vessel at the water level and the casing head, so that it may be lowered onto the head for connection thereto and raised tfrom the head and back to the vessel upon disconnection therefrom. It has been proposed to so guide drilling equipment through tubes having their lower ends sunk into the underwater level or otherwise lixed with respect thereto. However, these tubes are obviously unsuited for use in the great depths and turbulent wave conditions encountered in the drilling and completion of many modern offshore oil and gas wells. That is, they are so large as to impose excessive lateral loads on the wellhead and vessel between which they are connected.

For this reason, the industry has turned to a system for guiding such equipment which includes a pair of flexible cables anchored at their lower ends to the base of the casing head for extension upwardly to the vessel and collars or sleeves on the equipment providing followers for sliding vertically along the cables. One problem with this type of system is the necessity of threading and unthreading the cables through the followers of different equipment to be lowered and raised. This is not only a diliicult and time consuming operation, but also requires that the guide cables extend upwardly to at least the level orf the vessel and thus into the area of maximum wave action. More particularly, in operation, the cables are maintained taut by connection of their upper ends in some way to the vessel, as by means of a winch, which makes it diiiicult to remove the vessel from and return it to the guide system. Still further, in the event the cable kinks or bends, it may become impossible to move the follower over it in raising or lowering the equipment.

` An object of this invention is to provide a guide system of the general type above described which obviates the aforenoted shortcomings.

A more particular object is to provide such a system which is not susceptible to the large lateral loadings of the tubular type system, and which at the same time does not require threading or other intricate operations involved in the use of the flexible cable and follower type system.

Another object is to provide a guide system of this type which is of such construction that its upper end may be disposed beneath the more severe wave action.

A Lturther object is to provide a guide system of this type from which the vessel may be removed and to which fice the vessel may be returned with a minimum of preparation.

These and other objects are accomplished, in accordance with the illustrated embodiments of the invention, by a guide system in which at least three cables having their lower ends connected to the wellhead extend upwardly therefrom toward the water level in circumferentially spaced apart relation. The cables are held taut and thus vertically by a means at the upper ends, which preferably comprises one or more oats at a level beneath the vessel, so as to form a vertical passage through which the equipment may ybe lowered and raised. There is a rigid frame on the equipment which slides along and within the cables to guide it within the passage, and rigid bands connect the cables at vertically spaced levels to form a cage in which the cables are prevented from being spread apart a sufficient distance to permit the equipment to pass therethrough.

Since this system is just as open as the cable and follower type heretofore rused, it is just as free from lateral loadings. At the `same time, since` the equipment is merely constrained within the vertical passage within them, there is no need to thread the cables through the guide frame on the equipment. Furthermore, the upper end ost' the cage formed by the cables and bands need not be connected to the vessel and may, as above noted, be held taut merely by tioats at a level beneath the vessel. Thus, in operation, the equipment to be lowered from the vessel need only be stabbed into the upper end of the cage.`

In the drawings, wherein like reference characters are used throughout to designate like parts:

FIG. l is an elevational view of a guide system constructed in accordance with one embodiment of the presa ent invention for `use in raising and lowering equipment between an underwater wellhead at its lower end and a vessel at water level above its yupper end;

FIG. 2 is an enlarged perspective view of part of the guide system of FIG. l and illustrating the sliding engagement of the guide frame on the equipment with respect to the cables of the cage.

FIG. 3 is a cross sectional view of the system of FIGS. l and 2, as seen along broken line 3 3 of FIG. 1;

FIG. 4 is another cross sectional view of the guide systems of FIGS. l and 2, as seen along broken line 4-4 of FIG. 1; and

FIG. 5 is a perspective view of part of a guide system constructed in accordance with another embodiment of the present invention, and illustrating the equipment carried by the guide frame just prior to its being lowered onto the upper end of the wellhead to which the lower end of the guide cables are connected.

With reference now to the details of the above described drawings, -and particularly the embodiment of the invention shown in FIGS, l to- 4, a casing head 10 is shown in FIG. l to extend upwardly from a base 11 on the upper end of conductor casing 12. As well known `in the art, the conductor casing extends downwardly into a well bore drilled at the underwater level 13, and the casing and base are anchored to such level in a suitable manner.

During the drilling of this underwater well, additional strings of casing are lowered through and landed within the casing head 10. For this purpose, and as also shown in FIG. 1, there is a vessel 14 at the water level 15 from which such casing may be lowered into the well. Thus, a

. derrick 16 and the usual hoisting apparatus (not shown) are mounted above an opening 17 through the vessel so as to position in at least approximate alignment with the axis of the well during the drilling and completion procedure.

In order to maintain pressure control over the well during the drilling procedure, a blowout preventer 18 is lowered on a pipe 19 from the vessel 14 onto the upper end of the casing head 1l). More particularly, a device 20 is carried on the lower end of the preventer 18 for remote connection to a neck 21 about the upper end of casing head 10. This connecting device and the neck on the casing head may be constructed as shown generally in U.S. Patent No. 3,096,999, and modified in such a manner as to permit it to be actuated by suitable apparatus on the vessel at water level. As well known in the art, the preventer and its connector provide continuations of the bore through the tubing head so that the various strings of casing may be lowered through them and into the casing head.

The embodiment of the guide system of the present invention shown in FIGS. l to 4, includes six circumferentially spaced apart exible cables 22 connected at their lower ends to the base 11 by means of anchors 23. These cables are interconnected at vertically spaced apart levels by means of triangularly shaped rigid bands 24 which are welded or otherwise secured to the outer sides of the cables so as to provide the above described cage. Floats 25 are connected about the uppermost band 24 so as to hold the cables taut and thus vertically disposed. As shown in FIG. 1, the oats 25 are disposed beneath the vessel 14, and thus a substantial distance beneath the water level 15, so that they are subject to a minimum of wave action.

A triangularly shaped guide frame 26 is connected about the blowout preventer 18 by means of struts 27 or the like for guidably moving vertically within the cage formed by the interconnected cables 22 and bands 24.

More particularly, the frame 26 is symmetrical to each of the bands 24, and has outer dimensions somewhat smaller than the inner dimensions of each of the bands 24 so that its outer sides slide along the guide cables. This non-circular shape of the guide frame 26 and bands orient the equipment being lowered about its vertical axis, so that such equipment may be connected onto the casing head in a desired rotational position with respect thereto.

As previously noted, the bands 24 cooperate with the floats 25 in preventing the cables 22 from being spread apart a distance sucient to permit the guide frame 26 to move between any adjacent pair of them. Thus, the spacing of the bands vertically along the length of the cage depends on the number and normal spacing between ,the interconnected cables as well as the tension in the cables.

As shown in FIG. 1, there is a funnel 28 connected to the uppermost band 24 and diverging upwardly from its lower end to facilitate the operator in stabbing the guide frame 26 into the uppermost end of the cage. This funnel may include `an upper enlarged rigid band 29 connected to the uppermost band 24 of the cage by means of downwardly and inwardly converging rigid legs 30. It of course extends upwardly to a level relatively close to the bottom of the vessel 14 so as to perform its intended function.

This cage may be Iinstalled into the position shown in FIG. l in a number of ways. For example, the lower ends of the cables 22 may be connected to the anchors 23 for lowering with the base 11. To facilitate this, the floats may be made heavier when lowered with the upper end of the cage and then made lighter to hold the cables with the desired tension.

Upon installation of the apparatus illustrated and described above in connection with FIG. 1, the blowout preventer 18 and frame 24 are lowered on pipe 19 through the funnel 28 `and into the upper end of the cage. As the frame is guided downwardly through the cage, connector 2l) is lowered onto the neck 21 about casing head 10, and hydraulic controls are then actuated to cause the locking parts of the connector to fasten onto the neck. The pipe 19 is then backed otf from the blowout preventer and raised from within the cage of the guide system, and the casing strings are lowered through the guide system and into the casing head in the drilling procedure.

Obviously, upon completion of the drilling process, this same guide system may be used in lowering a Christmas tree onto the wellhead. In either case, the vessel 14 may be moved away from the well site without having to be disconnected from the guide system. Conversely, the vessel need only be moved back into the position of FIG. 1 in order to continue the drilling and/ or completion of the well. Y

In many respects, the guide system illustrated in part in FIG. 5 is similar to the system illustrated and described in FIGS. l to 4. Thus, it includes at least three circu-mferentially spaced apart flexible cables 31 connected at their lower ends to a base about casing head 10 for extension upwardly therefrom. As shown in FIG. 5, there are four such cables generally equally spaced apart and `interconnected at vertically spaced apart levels by means of rigid bands 33. The upper end of the cage formed by the interconnected cables and bands is provided with oats and preferably a funnel similar to those shown in FIG. 1 so as to hold the ables taut and facilitate stabbing of equipment into the cage.

In this embodiment of this invention, each of the bands 33 is of circular configuration in a section taken perpendicular to the axis of the well and the cage. The guide frame 34 connected to the blowout preventer :18 or other equipment to be guidably raised and/or lowered with respect to the casing head 10 is similarly shaped and of somewhat lesser outside `dimensions than the in side dimensions of the bands 33. Thus, the outer circular side of the guide frame 34 moves slidably along the inner side of the cables 31 which are, in turn, welded or otherwise secured a-t their outer sides to the inner sides of the bands 33.

As in the case of the guide system shown in' 'FIGS'. 1 to 4, this latter guide system enables equipment such as the blowout preventer 18 to be lowered into a posiy tion for connection -to the casing head 10 by means of a device 20 carried beneath the blowout preventer and having locking parts for connecting about the neck 21 on the upper end of the casing head. Also, of course, the spacing between adjacent bands 33 is dictated by the number and spacing of `the cables as well as the tension in the cables, whereby adjacent cables are kept from being spread apa-rt a distance which would permit the guide frame 34 to move between them.

Inasmuch as the guide frame and guiding sufaces of the cage are circular, they will not in and of themselves lorient the equipment about its vertical axis. Thus, in order to permit the equipment to be connected to the' casing head 10` in a desired rotational sense, there is a camming ring 35 on the wellhead with which a cor- `respondingly shaped camming ring 36 connected on the guide frame 34 is adapted to cooperate. As shown in FIG. 5, the cam ring 35 is supported above a circular frame 32 connected to the casing head with its upper' camming `surface in an angularly disposed position with respect to the axis of the well and cage of the guide systern. Similarly, the cam `ring `36 is carried beneath the guide frame 34 by means of one or more vertical rods `37 extending down from the lower side of the guide frame 34 to dispose its lower camming surface `at substantially the same angle.

As the connector 20 approaches a landed position on the neck 21 of the casing 'head 10i, the lower surface on cam ring 36 will engage with the upper surface on cam ring 35 so as to orient `the equipment into the desired position. That is, the mere weight of the equipment will cause the upper cam ring 36 to turn about its axis until its lower surface is disposed parallel to the upper surface of cam ring 35. This embodiment is preferred over that shown in FIGS. 1 to 4 since it does not require that the operator lower the guide trarne into the cage in any predetermined relationship 'about a vertical axis.-

As in the case of the guide system shown in FIGS. 1 to 4, the system shown in FIG. 5 may also be used in raising and lowering a Christmas tree with respect to the wellhead during the completion process. Inasmuch as the system functions in the same manner as that shown and described in connection with FIG. 4, this procedure need not be explained again.

From the foregoing, it will be `seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be unders-tood that certain features and subcombinations are of utility and may be employed with- ;out reference to other features and subcombinations. This is contemplated `by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying d-rawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

`1. In a system for guiding equipment between water level and a wellhead at an underwater level, at least three flexible cables having their lower ends connectable to the wellhead for extension upwardly therefrom in circumferentially spaced apart relation, means on the upper ends of the cables for holding them taut, and rigid bands connecting the cables .a-t vertically spaced apart levels.

2. In a system for use in drilling and/ or completing an underwater well, a wellhead at the underwater level, at lest three exible guide cables having their lower ends connected to the wellhead in circumferentialy spaced apart relation, rigid bands connecting the cables at spaced apart vertical levels between their upper and lower ends, and means on the upper ends of the cables holding them taut so as to provide a vertically disposed passage through which equipment may be passed between water level and said wellhead.

3. A system for guiding equipment between a vessel `at water level and a wellhead located at an underwater level, comprising at least three circumferentially spaced Aapart llexible cables extendable vertically upwardly from said wellhead .toward a vessel at the water level, a rigid frame connectable about the equipment for sliding along and with the cables to guide the equipment for vertical passage Ibetween said vessel and said wellhead, and rigid bands connecting the cables at spaced apart vertical levels to maintain the cables sufficiently close together to prevent said frame from passing between any two of them.

y4. A system of the character defined in claim y3, wherein said frame has a non-circular portion slidable along said cables so as to maintain it in a predetermined rotational position during such passage.

5. A system for use in drilling `and/or completing a well at an underwater level, comprising a wellhead at the underwater level, -at least three circumferentially spaced apar-t flexible cables extending vertically upwardly from said well-head toward a vessel at water level, rigid 4bands connecting the cables at spaced .apart vertical levels, and equipment adapted for connection to the wellhead and having rigid guide means thereabout for sliding along and within the cables between said vessel and said wellhead.

6. A system of the character defined in claim 5, wherein said guide means and said wellhead have means providing cam surfaces for orienting said equipment into a desired rotational position with respect to the wellhead as it is lowered onto the wellhead.

References Cited by the Examiner UNITED STATES PATENTS 987,266 3/1911 Smith 175--9 1,175,725 y3/1916 Dunbar 175-10 3,015,360 '1/1962 Stratton 175-7 X 3,017,934 1/1962 -Rhodes et al. 175-7 X 3,111,692 11/1963 COX 175-8 X 3,177,954 4/1965 Rand 175--7 3,209,827 10/ 1965 Lacy et al. 175-7 X ERNEST R. PURSER, Primary Examiner.

CHARLES E. OCONNELL, Examiner.

R. FAVREAU, Assistant Examiner.

Claims (1)

1. IN A SYSTEM FOR GUIDING EQUIPMENT BETWEEN WATER LEVEL AND A WELLHEAD AT AN UNDERWATER LEVEL, AT LEAST THREE FLEXIBLE CABLES HAVING THEIR LOWER ENDS CONNECTABLE TO THE WELLHEAD FOR EXTENSION UPWARDLY THEREFROM IN CIRCUMFERENTIALLY SPACED APART RELATION, MEANS ON THE UPPER ENDS OF THE CABLES FOR HOLDING THEM TAUT, AND RIGID BANDS CONNECTING THE CABLES AT VERTICALLY SPACED APART LEVELS.

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