US3501173A

US3501173A - Tubular connector for lightweight marine conductor pipe

Info

Publication number: US3501173A
Application number: US720245A
Authority: US
Inventors: William H Petersen; William H Linder
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1968-04-10
Filing date: 1968-04-10
Publication date: 1970-03-17
Anticipated expiration: 1987-03-17
Also published as: DE1917819A1; GB1251262A; FR2005941A1

Description

March 17,

1970 w. H. PETERSEN E A TUBULAR CONNECTOR FOR LIGHTWEIGHT MARINE CONDUCTOR PIPE FIG." 5

Fil ed April 10. 1968 INVENTORSI WILLIAM H. LINDER WILLIAM H. PETERSEN BY'I z THEIR ATTORNEY Patented Mar. 17, 1970 11.8. Cl. 285-114 2 Claims ABSTRACT OF THE DISCLOSURE A marine conductor pipe constructed of a plurality of lightweight pipe sections releasably attachable to one another in an end-to-end manner. Each pipe section includes a conduit member constructed of lightweight material and defining a throughbore. Each end of the conduit is attached in a fluid-tight manner to relatively rigid coupling members defining throughbores axially aligned with each other and with the throughbore defined by the conduit member. Suitable reinforcing members are used to limit the maximum distance between the two coupling members to substantially the effective operative length of the conduit member. The reinforcing members extend lengthwise along the entire length of the conduit member and are attached to both of the coupling members.

This invention relates to apparatus for use in drilling, completing and working-over operations in oil and gas wells at offshore locations, and pertains more particularly to apparatus adapted to provide full-flow fluid communication between a vessel at the surface of a body of water and a wellhead assembly positioned on the ocean floor or at a substantial depth below the surface of the water.

In an attempt to locate new oil fields, an increasing amount of well drilling has been conducted at offshore locations, such for example, as off the coast of Louisiana, Texas and California. As a general rule, the strings of casing in a well, together with the tubing strings or string, extend to a point above the surface of the water where they are closed in a conventional manner that is used on land wells, with a conventional wellhead assembly being attached to the top of the casing. Recently, methods and apparatus have been developed for drilling and completing Wells wherein both the Well casinghead, and subsequently the wellhead assembly and easing closure device, are located under water at a depth suflicient to allow ships to pass over them. Preferably, the casinghead and the wellhead closure assemblies are located close to the ocean floor. In order to install well drilling equipment underwater at depths greater than the shallow depth at which a diver can easily operate, it has been necessary to design entirely new equipment for this purpose.

Wells drilled in deep water are generally drilled from vessels of varying designs commonly known as drilling barges, vessels or platforms. Deepwater wells are gen erally drilled by one of two methods. In one method the string of drill pipe extends downwardly from the drilling barge to the drilling wellhead assembly on the ocean floor which is closed at the top by a circulation head with a flexible hose running from the circulation head back to the surface and to the drilling barge so that drilling fluid may be circulated down the drill pipe, through the drill bit, and thence upwardly on the outside of the drill pipe, out the circulation head and up the flexible hose to the barge again. In the second method, a large-diameter pipe known as a marine conductor pipe is put together and arranged to extend from the drilling wellhead assembly on the ocean floor to the barge on the surface of the water. In the latter method, the drill pipe rotates within the conductor pipe with drilling fluid being circulated down through the drill pipe, through the bit at the bottom thereof, up the outside of the drill pipe and thence upwardly through the annular space between the conductor pipe and the drill pipe, returning to the barge in the conventional way. The present invention is concerned with apparatus to be used in the second method described hereinabove.

Offshore drilling operations are being carried out in waters of increasingly greater depth. Since a marine conductor pipe is normally constructed of steel or other relatively heavy metal, providing proper support for such conductor pipe at these greater depths becomes increasingly diflicult. It has been found undesirable to attempt to support the weight of this pipe on the underwater wellhead structure so all or substantially all of the weight of the marine conductor pipe is either supported by means of constant tension hoists on the floating vessel or by means of buoyancy tanks secured to the outside of the marine conductor pipe, or a combination of these two arrangements.

In deep water locations, say, 3,000 feet deep, it would be necessary to increase the size of the buoyancy tanks on the heavy marine conductor pipe to an extent that they would become quite enormous, thus possessing large areas against which wave forces and underwater currents could act in a manner causing the marine conductor pipe to deflect from its normally vertical position within the water. If the pipe is allowed to deflect too far from its normal vertical position, it may be permanently bent or ruptured. Alternatively, if constant tension hoists are to be employed to apply tension to the top of the heavy marine conductor pipe from the vessel, larger and more buoyant vessels would have to be employed as well as vessels having larger hoists.

Summary of the invention It is therefore a primary object of the present invention to provide a marine conductor pipe of lightweight construction which may be employed in deep water drilling depths without rendering it necessary to employ either inordinately large buoyancy tanks or vessels to provide support therefor.

Another object of the present invention is to provide a marine conductor pipe comprised of readily attachable and detachable pipe sections, each section being of lightweight construction.

Still another object of this invention is to provide a marine conductor pipe constructed of lightweight materials and employing reinforcement means for imparting additional structural strength thereto.

These and other objects have been attained in the present invention by providing a marine conductor comprising a plurality of elongated pipe sections detachably interconnected in an end-to-end manner, each pipe section including a lightweight, large diameter conduit means having coupling means secured in a fluid-tight manner to each end thereof. Reinforcement means extend along substantially the length of the conduit means to limit the maximum distance between said coupling means to substantially the effective operative length of the conduit means.

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

FIGURE 1 is a diagrammatic view taken in longitudinal projection illustrating a floating drilling vessel positioned at the surface of a body of water with a marine conductor pipe according to the present invention extending from the vessel and being operatively associated with 3 an underwater wellhead assembly positioned at the earth under the water;

FIGURE 2 is a cross-sectional view of a section of marine conductor pipe according to the present invention showing the section operatively associated with cooperating elements of adjoining sections;

FIGURE 3 is an enlarged, cross-sectional view illustrating a preferred means of attaching together elements of a pipe section;

FIGURE 4 is a cross-sectional view taken along the line 4 4 of FIGURE 2; and

FIGURE 5 is an enlarged, partial cross-sectional vieW illustrating a portion of an alternative embodiment of the present invention.

Referring now to FIGURE 1 of the drawing, a drilling barge or platform is represented by numeral 11. The drilling barge or platform 11 is of any suitable type, preferably one, as illustrated, floating at the surface of a body of water 12 and substantially fixedly positioned over a preselected drilling location by suitable barge positioning means or by being anchored to the ocean floor 13 by suitable anchors (not shown) connected to the anchor lines 14 and 15. Equipment of this type may be used when carrying on well drilling operations in water depths varying from about 100 to 1500 feet or more. The drilling barge is equipped with a conventional derrick 16 as well as other auxiliary equipment (not shown) needed during the drilling of a well such as a hoist system, draw works, rotary table, etc. The derrick 16 may be positioned over a drilling slot 17 which extends vertically through the barge in a conventional manner. The slot 17 in the vessel 11 may be either centrally located or extend in from one edge. Alternatively, drilling operations may be carried out over the side of the vessel without using a slot. For example, the drilling vessel may be provided with a deck portion which overhangs the hull on the vessel.

It is to be understood that the underwater well may be started by any of the methods well known to the art wherein a foundation pile or a casing 18 is installed in the hole drilled in the earth and secured therein, as by means of cement 19. The underwater wellhead assembly comprises or includes a base member 20 fixedly secured to the foundation pile 18. A drilling wellhead assembly is run down and connected to the wellhead assembly by any conventional well known procedure such as by use of guide lines, pipe string lowering arrangements, etc.

A typical drilling assembly comprises a wellhead connector 21, ram-type blow-out preventer 22, sleeve-type blow-out preventer 23 and a marine conductor pipe 24 which extends upwardly to the vessel 11. The upper end of marine conductor pipe 24 has attached thereto lines or

cables

25 and 26 which are in turn positioned over rotatable pulley elements mounted on vessel 11. Lines or

cables

25 and 26 have attached to their respective

free ends counterweights

27 and 28 which, for ease of illustration, are shown as carried on the outside of the vessel, but which are generally arranged within the vessel. With this arrangement, tension is applied along the length of marine conductor pipe 24 to keep it from buckling under its own weight and the weight of the column of mud in the conductor pipe during drilling operations. A telescopic joint 24' is preferably provided at the upper end of the conductor pipe to compensate for up-and-down movement of the vessel in the usual manner. The particular illustrated tension means is shown by way of example only and forms no part of the present invention. It is to be understood that any suitable tensioning means, constant tension winches, etc., could be used for the purpose of applying tension to the marine conductor pipe. A mud return hose (not shown) leads mud from the top of conductor pipe 24 to a mud pit (not shown) on the vessel 11 in the well known manner during drilling operations.

Marine conductor pipe 24 is comprised of a series of elongated pipe sections 29 which are connected in an end-to-end manner to provide a drilling passage for a drill string. The lowermost section of marine conductor pipe 24 may be fixedly secured to the top of blow out preventer 23 by any suitable means. Seal means normally will be provided between blow-out preventer 23 and its associated pipe section 29 to assist in forming a liquid-tight seal therebetween.

Referring now to FIGURE 2, a pipe section 29 is shown in cross-section. Pipe section 29 includes a large diameter conduit member 30 defining a throughbore 30'. Conduit member 30 may be formed of a metallic or non-metallic material and is preferably constructed of a lightweight, water-proof material such as fiberglass, flexible plastic, fabric, synthetic rubber or the like. A relatively rigid first coupling member 31 is attached to conduit member 30 at one end thereof.

First coupling member 31 defines a throughbore 31' which is disposed in axial alignment with the throughbore 30 defined by conduit member 30. First coupling member 31 is of substantially cylindrical construction and includes an outwardly extending circular flange member 32 and a circular connector groove 33. A recessed circular clamping channel 34 is preferably formed on the outer surface of coupling member 31 beneath circular flange member 32 and is adapted to receive one end or a portion of conduit member 30 in the manner shown in FIGURE 2 and FIGURE 3. With particular reference to FIGURE 3, the cooperating end of conduit member 30 is clamped into fluid-tight engagement with clamping channel 34 by means of a U-clamp member 35 of conventional design or any other suitable clamping or bonding means well known in the art. Suitable means, such as clamping bolt 36, may be used to vary the degree of clamping pressure exerted by clamp 35 on the end of conduit member 30 and clamping channel 34 in the usual manner. Although a U-clamp construction has been illustrated for effecting fluid-tight attachment between conduit member 30 and first coupling member 31, it is obvious that any suitable locking or clamping device may be used for such purpose.

Returning now to FIGURE 2, circular flange member 32 has a plurality of tapped holes or threaded recesses 37 therein which are matingly engaged with the threaded ends of reinforcement members 38 which in this case comprise tie rods. Reinforcement members 38 extend substantially along the length of conduit member 30 and terminate at threaded end members 39. The threaded end members 39 pass through apertures 40 in a second flange member 41 comprising a portion of second coupling member 42. Second coupling member 42 defines a throughbore 42. which is coaxial with and in communication with

throughbores

30, 31.

Lock nuts

43 and 44 threaded on end members 39 on opposite sides of second flange member 41 are used to retain reinforcement members 38 in a predetermined fixed position with respect thereto. FIGURE 4 illustrates this arrangement in more detail.

Second coupling member 42 also includes a second clamping channel 45 (FIGURE 2) which engages conduit member 30 by means of a second clamp 46. Second clamp 46 may be of the same type as clamp 35 and the operation thereof will 'be similar. Once again, any suitable clamping or coupling arrangement may be utilized to effect fluidtight attachment between conduit member 30 and the

coupling members

31, 42.

The construction of second coupling member 42 ditfers from that of first coupling member 31 in that the second coupling member 42 has no connector groove similar to groove 33. Instead, second coupling member 42 has a depending skirt or female connector portion -47 of enlarged internal diameter which is provided with one or more set screws 48 operatively associated therewith. The enlarged housing skirt 47 is adapted to be placed over the first coupling member of an adjoining pipe section and the set screw 48 is screwed inwardly through the wall of skirt 47 to engage the connector groove 33 of the adjoining pipe section thereby releasibly attaching the pipe sections together. Broken away portions of adjoining pipe sections are shown to illustrate more clearly this method of attachment.

If desired, wear rings 49 may be disposed in conduit member 30 to help protect conduit member 30 from damage due to contact with a rotating drill string (not shown) which in the drilling operation passes through the marine conductor pipe. The wear rings are preferably constructed of steel and are fixedly attached or bonded by any suitable means to the inner wall of conduit member 30.

As has been described previously, the marine conductor pipe 24 is maintained under tension throughout its length during the drilling operation. Accordingly, it is not necessary for the various pipe sections 29 comprising the conductor pipe to be particularly resistant to endwise compressive forces. The primary function of the reinforcement members is to limit the maximum distance between the first coupling member 31 and the second coupling member 42 to substantially the effective operative length of conduit member 30. In other words, the reinforcement means utilized should be particularly effective to resist endwise tension forces applied to the pipe section to prevent the coupling members from being pulled away from the pipe section conduit members, For this reason, tie rods of relatively small thickness, or even cables, may be used as reinforcement members, thereby keeping the weight of each pipe section at a minimum.

FIGURE 5 illustrates one possible alternative embodiment of the present invention wherein a cable would be used as the reinforcement member. FIGURE 5 is an enlarged, partial sectional view illustrating a portion of a conduit member 30 having molded or imbedded therein a cable 50, comprising the reinforcement member, which would extend the full length of conduit member 30 and be attached by any desired means to the pipe section coupling members. Any suitable flexible non-metallic relatively lightweight pipe having means limiting its axial extension may be used as conduit members 30.

While this invention has been described with particular reference to preferred embodiments thereof, it should be understood that the forms illustrated herein have been selected to facilitate the disclosure of the invention rather than to limit the number of forms which it may assume, and various modifications, adaptations and alterations may be applied to the forms shown to meet the requirements of practice without departing from the spirit or scope of the present invention. For example, a wide variety of materials may be utilized in the construction of the pipe section conduit member. In addition, various fastening arrangements could be used to attach the reinforcement members to the coupling members. Also, couplings could be used that feature locking mechanisms other than the set screw method described herein (i.e., screwed joints, wedge locks, dogs, etc.). The reinforcement members could, if desired, be disposed within the throughbore of the conduit member. Although not illustrated herein, the subject invention could be used in conjunction wi-th buoyancy tanks as is a common practice in underwater drilling operations.

We claim as our invention:

1. A marine conductor adapted to extend trom a floating vessel on the surface of a body of water to a well head assembly on the earth underlying said body of water, said marine conductor comprising:

a plurality of elongated pipe sections detachably interconnected in an end-to-end manner, each pipe section including a lightweight, large-diameter conduit formed of fiberglass material and defining an axial throughbore;

a first coupling member operatively associated with one end of said conduit, said first coupling member comprising a cylindrical element defining a throughbore in substantially axial alignment with said conduit throughbore, an outwardly extending circular flange member fixedly secured to the cylindrical element and a channel formed in said cylindrical element on at least one side of said flange member, said channel receiving one end of said conduit, and clamping means extending substantially about the periphery of said channel securing said conduit end to said first coupling member in a fluid-tight manner;

a second coupling member operatively associated with the other end ofsaid conduit and defining a throughbore in substantially axial alignment with the throughbore of said conduit, said second coupling member including an enlarged portion adapted to receive the cylindrical element of a first coupling member of another pipe section, a second outwardly extending circular flange member spaced from said enlarged portion, a second channel adapted to receive the other end of said conduit, and second clamping means extending substantially about the periphery of said second channel and securing said other conduit end to said second coupling member in a fluid-tight manner;

a plurality of elongated members secured to said flange members and extending between said first flange member and said second flange member whereby the maximum distance between said first coupling member and said second coupling member is limited to substantially the effective operative length of said conduit, said elongated members being positioned with respect to said flange members whereby the elongated members are maintained out of engage: ment with said clamping means when said elongated members are subjected to tensile stress; and

a plurality of spaced wear rings connected to the inner wall of said conduit to protect the conduit from the potentially harmful wearing action of a rotating drill string within the pipe section during drilling operations.

2. The marine conductor according to claim 1 wherein said elongated members comprise tie rods threadedly connected to said flange members.

References Cited UNITED STATES PATENTS 833,426 10/1906 Taube 285-114 993,934 5/1911 Witzenmann 285-114 1,366,694 l/l921 Kors 285-114 1,384,962 7/1921 Kuhne 285-114 2,305,644 12/1942 Stone 285-114 X 2,536,216 l/ll Powell 285-114 X 2,809,699 10/1957 Battle 166-242 X 3,142,344 7/1964 Otteman et al. 166-.5 X 3,155,175 11/1964 Johnson 285-404 X 3,168,334 2/1965 Johnson 285-223 X 3,347,566 10/1967 Nelson 285-114 X 3,170,720 2/1965 Browning 285-114 3,232,640 2/ 1966 Donkle 285-114 X THOMAS P. CALLAGHAN, Primary Examiner US. Cl. X.R.