Flexible pipe joint having deflection limiting means

June 15, 1965 g. d. Johnson 3,189,372

FLEXIBLE PIPE JOINT HAVING DEFLECTION LIMITING MEANS

Filed May 24, 1962 ο ,

Sheets-Sheet 1

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HIS AGENT

June 15, 1965 g. _D Johnson 3,189,372

FLEXIBLE FIFE JOINT HAVING DEFLECTION LIMITING MEANS

Filed May 24, 1962

Sheets-Sheet 2

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FIG. 3

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INVENTOR: GLENN D. JOHNSON

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HIS AGENT

United States Patent Office

3,189,372

Patented June 15, 1965 ¹

3,189,372

FLEXIBLE PIPE JOINT HAVING DEFLECTION LIMITING MEANS

Glenn D. Johnson, Downey, Calif., assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware

Filed May 24, 1962, Ser. No. 197,325

Claim. (CI. 285—91)

This invention relates to a flexible joint for pipes and pertains more particularly to a flexible joint for largediameter pipes such as marine conductor strings that are employed in drilling offshore oil and gas wells.

In recent years methods and apparatus for successfully drilling wells at underwater locations has been developed. Most important have been the developments wherein it is possible to drill and complete a well on the ocean floor wherein the entire wellhead assembly is positioned at or near the ocean floor at a depth at least sufficient to avoid being a navigation hazard to ocean-going vessels. Offshore or underwater wells may be drilled from a suitable vessel such as a drilling barge or from a platform which has been floated into position over a selected location and then extend legs downwardly to the ocean floor so that the operating platform remains above the surface of the water to carry out drilling operations.

In drilling from a floating barge consideration must be given to the fact that a barge, even though anchored, possesses some movement. Thus, equipment such as drill strings and marine conductor pipes extending downwardly from the barge to the ocean floor must possess some degree of flexibility so that they are not ruptured when the barge moves slightly off location. In general, drill pipe is of a diameter sufficiently small and is constructed sufficiently strong so that it possesses a relatively high degree of flexibility and is not subject to damage as much as other equipment. A marine conductor pipe, however, which is normally used to surround a drill string in offshore locations so that drilling mud may be returned up the annulus between the inner wall of the conductor pipe and the outer wall of the drill string, is usually of considerably greater diameter and thus possesses little flexibility.

_ It is therefore a primary object of the present invention to provide a flexible joint for use in a marine conductor pipe depending from a drilling barge to the ocean floor to give sufficient flexibility to the marine conductor so that the barge need not keep the marine conductor in a vertical plane at all times.

A further object of the present invention is to provide a rugged flexible pipe joint capable of withstanding the forces to which a marine conductor pipe is subjected during offshore drilling operations.

Another object of the present invention is to provide a flexible pipe joint for a marine conductor pipe string, said flexible joint being provided with means for limiting the declination or angle of tilt of the joint so as to prevent rupture of the joint.

A still further object of the present invention is to provide a flexible pipe joint having the wall thereof capable of protecting the sealing elements of the flexible joint, said flexible joint being sectionalized with interlocking and readily removable sections.

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 a drilling barge positioned above a drilling location at an offshore location where the wellhead assembly is positioned on the ocean floor;

FIGURE 2 is a longitudinal view taken in partial cross section of one form of the flexible pipe joint assembly of the present invention; and

FIGURE 3 is a vertical isometric projection of one assembly section of the present flexible joint.

Referring to FIGURE 1 of the drawing, a drilling barge, vessel or platform 11 is illustrated as floating on 5 the surface 12 of the body of water 13 above a drilling location wherein an underwater wellhead assembly 14 is positioned on the ocean floor 15. A large-diameter marine conductor pipe 16 is secured by means of a wellhead connector 17 to the upper end of the wellhead assem10 bly, generally represented by 14. In the arrangement shown, the wellhead connector 17 is connected to the top of a blow-out preventer 18, illustrated as being mounted on dual ram-type blowout preventers 20 which in turn are suitably connected to the casinghead 21 of the well15 head assembly 14. The upper end of the marine conductor pipe 16 is secured in any suitable manner well known to the art to the vessel 11, as by means of cables 22 and 23 which position the top of the marine conductor pipe 16 more or less centrally in a drilling slot 24 which ex20 tends through the vessel 11.

Although the marine conductor pipe 16 is illustrated as being a continuous pipe or tubular element, it is normally made up of a plurality of relatively short sections of pipe secured together in any well known manner. Posi25 tioned in the marine conductor pipe intermediate ends thereof are one or more flexible joints generally represented by numeral 25 in FIGURE 1 and shown in detail in FIGURE 2. During drilling operations a string of drill pipe normally extends from the vessel 11 down 30 through the length of marine conductor pipe 16 and into the well.

The flexible pipe joint assembly 25 of the present invention is shown in FIGURE 2 as being made of a plurality of tubular assembly sections 26, 27, 28, 29, 30, 35 and 31. The intermediate assembly sections 27, 28, 29 and 30 are identical in construction while the end assembly sections 26 and 31 differ only in that they are provided with suitable connector means whereby they may be connected to a pipe or another piece of associated equipment ⁴⁰ being used with the flexible pipe joint assembly. Thus, the upper assembly section 26 is provided with threads 32 for securing it to the lower end of the marine conductor pipe 16 while the lower assembly section 31 is provided with threads or a flange 33 whereby the lower assembly ⁴⁵ section may be fixedly secured to the wellhead connector 17.

The adjacent ends of each pair of assembly sections are provided with suitable cooperating connector means adapted to engage one another to prevent the separation 50 of the pair of assembly sections. In the preferred embodiment of the present invention the connectors for securing the assembly sections together are in the form of a plurality of inwardly-extending lugs 35, the bottom faces of which are adapted to engage the upper faces of a corre⁵⁵ spending series of outwardly-facing lugs 36 arranged on the adjacent wall of the adjacent assembly section. As will be seen from the FIGURES 2 and 3, the outwardlyextending lugs 36 are positioned on a reduced-diameter portion 37 of each of the assembly sections which fits θθ telescopically within the bore of the upper end of the adjacent end of the assembly section which is of normal diameter. As shown in FIGURE 3, the spacing between the inwardly-extending lugs 35 is less than the width of the outwardly-extending lugs 36 while the spacing 39 ^{65 bet}ween the outwardly extending lugs 36 is less than the width of the inwardly extending lugs 35, whereby the lugs 36 will be insertable past the lugs 35 of an adjacent section and they are adapted to be rotated, one assembly 70 ^rct^at^]Ve to the other, until the lugs 36 are positioned directly beneath the lugs 35.

Two assembly sections, for example, assembly sections

3,189,372 ³

8, 29 (FIGURE 2), are fixedly secured against relative □ation one with another by means of locking plugs which re countersunk within each assembly section with the inzardly-extending end of the plug 41 being positioned in a ertical slot 42 in the outwardly-extending lugs 36. The 5 lots 42 are preferably of substantial length in the direcion of the axis of the assembly section so as to permit he movement of a plug therein as one assembly section s tilted relative to the adjacent assembly section.

Mounted between each pair of assembly sections of the io iexible pipe joint is an annular sealing ring or element 43 dapted to form a fluid tight seal between adjacent assemily sections. The annular sealing ring 43 is positioned on op of the inwardly-extending lugs 35 while a second anlular sealing ring 44 is preferably employed below the 13 mtwardly-extending lugs 36. In order to maintain the esilience seals 43 and 44 in circular form, it is preferred hat split metal rings 45 and 46 be employed between the ealing rings or packing elements 44 and 43 and the adjaent lugs on which they .are positioned. In assembling any 20 wo assembly sections of the present flexible pipe joint, it 5 necessary to apply a force axially to compress the sealtig elements 43 and 44 sufficient so that one assembly secion may be rotated slightly relative to the other so that he lugs 35 and 36 interlock. When the pipe joint is as- 25 embled all of the sealing elements 43 and 44 remain in tompression at all times, that is, when the axis of the fiexi>le pipe joint is in a vertical line or at the time it has been lexed to one side or the other. Thus, the sealing elements 13 and 44 between adjacent assembly sections may be con- 30 idered resilient compression rings.

In order to protect the flexible pipe joint assembly of he present invention and especially the annular sealing ings thereof, the flexible pipe joint assembly is provided vith suitable deflection limiting means which may take 35 everal forms. For example, the deflection of one assem>ly section 30 relative to its adjacent section 31 may be :ontrolled by limiting the width of the spaces 45α and \6a between the outwardly extending lugs 36 of section >0 and the adjacent inner wall of section 31, and in a like 40 nanner the spacing between the inwardly extending lugs !5 of section 31 and the wall facing it of section 30. fhus, the wider the spaces 45 and 46, the more play or leflection that is possible between sections 30 and 31. Another form of deflection limiting means comprises the 45 brmation of cooperating shoulders 47 and 48 on adjacent issembly sections, the shoulder 47 is provided on the reluced diameter portion 37 of each assembly section and s adapted to engage any of the shoulders 48 formed on he inner surface of the inwardly extending lugs 35 of the 50 idjacent sections. It may be seen that when shoulders 47 md 48 engage one another the compression sealing rings 13 cannot be compressed further.