EP3140494B1 - Section of a riser provided with a locking ring arranged between the main tube and the auxiliary tube - Google Patents

Description

The present invention relates to the field of drilling and oil exploitation of deposit in very deep sea. It concerns a riser section.

A riser (or "riser") is formed by a set of tubular elements of length between 15 and 27 m (50 and 90 feet), assembled by connectors. The tubular elements generally consist of a main tube provided with connectors at each end. Tubular auxiliary pipes also called peripheral pipes commonly called "kill line", "choke line", "booster line" and "hydraulic line" allowing the circulation of technical fluids are provided parallel to the main tube. The tubular elements are assembled on the drilling site, from a floating support. The column descends into the water portion as the assembly of the tubular elements, until reaching the wellhead located on the seabed.

In order to drill at water depths up to 3500 m or more, the weight of the riser becomes very penalizing. This phenomenon is aggravated by the fact that, for the same maximum operating pressure, the length of the column imposes an inner diameter of the auxiliary lines larger given the need to limit the pressure losses.

Furthermore, the need to reduce the assembly time of the risers is all the more critical as the water depth, and therefore the length of the column, are important.

The document FR 2526517 describes a riser connector, with an external locking ring. The document WO 2011/104629 describes a riser connector, with a locking ring at the periphery of the flanges.

The documents FR 2925105 , FR 2956693 and FR 2956694 describe various solutions including proposing to involve the auxiliary pipes, together with the main tube, the recovery of the longitudinal forces applied to the riser. However for the systems described in these patents, the attachment of the auxiliary lines relative to the main tube causes tensile forces in the auxiliary lines. In order to resist these tensile forces, the thicknesses of the auxiliary lines are large, which generates an increase in the mass, the size of the floats and consequently the cost of the riser. In addition, the connectors proposed in these patents are not not completely removable which makes it difficult to inspect and maintain the riser.

Advantageously, the first and second series of tenons comprise two rows of tenons, and the third and fourth series of tenons comprise a row of tenons.

According to the invention, each series of tenons is composed of at least two rows of at least four tenons.

Advantageously, a sleeve is fixed inside said male connector element, said sleeve being able to cooperate with the female connector element to form a tight connection.

According to one embodiment of the invention, said riser section comprises a locking ring cooperating with the peripheral surfaces of said flanges to assemble said flanges.

Preferably, the inner face of said locking ring is provided with a first set of tenons and the peripheral surface of the flange of said female connector element comprises a second set of tenons.

According to an alternative embodiment of the invention, the inner face of said locking ring is provided with a third series of tenons and the peripheral surface of the flange of said male connector element comprises a fourth series of tenons adapted to cooperate with said third series of tenons.

According to one aspect of the invention, said auxiliary tube member is a steel tube shrunk by reinforcing threads, such as glass, carbon, or aramid fibers embedded in a polymer matrix.

According to an alternative embodiment of the invention, said auxiliary tube element is integral with the two flanges of said male and female connector elements.

Alternatively, said auxiliary tube element is integral with a flange of said male and female connector elements and is connected by a sliding pivot connection with the other flange of said male and female connector elements, said sliding pivot connection allowing a relative translational movement between said main tube member and said auxiliary tube member to a limited distance by game adjustment means placed on said auxiliary tube member.

Advantageously, said game adjustment means is formed by a nut or a threaded piece.

According to a first aspect, said auxiliary tube element is extended on the one hand by a female end and on the other hand by a male end equipped with a nut.

According to a second aspect, said auxiliary tube element is extended on the one hand by a female end and on the other by a receptacle, in which is inserted a male pin equipped with a stop.

According to a third aspect, said auxiliary tube element is extended on the one hand by a receptacle, in which is inserted a female pin, and on the other hand by a receptacle, in which is screwed a male threaded pin, said male threaded pin comprising a shoulder.

Preferably, said distance is limited by said clearance adjustment means is from 0 to 31.75 mm, preferably from 2.54 mm to 25.4 mm.

In addition, the invention relates to a riser comprising at least two riser sections according to the invention, for which the connection between two consecutive sections is carried out by means of said male and female connector elements and said locking ring.

Advantageously, said distance of the relative translation movement of said sliding pivot connection is set so as to be positive when connecting at least two sections of said riser, and to be zero when using said riser. .

The invention also relates to the use of a riser according to the invention for carrying out a well drilling operation at sea.

Brief presentation of the figures

• La figure 1 schématise une colonne montante selon l'invention.
• La figure 2 illustre un tronçon de colonne montante selon un mode de réalisation de l'invention.
• La figure 3 illustre la connexion de deux tronçons de colonne montante selon un premier mode de réalisation de l'invention.
• La figure 4 illustre une vue éclatée avant connexion de la bague de verrouillage et l'élément connecteur femelle selon une variante de réalisation de l'invention.
• La figure 5 illustre une bague de verrouillage selon une variante de réalisation de l'invention.
• La figure 6 illustre la connexion de deux tronçons de colonne montante selon un deuxième mode de réalisation de l'invention.
• La figure 7 illustre un anneau de verrouillage pour le deuxième mode de réalisation de l'invention.
• Les figures 8 à 10 représentent trois variantes de réalisation selon l'invention d'une ligne auxiliaire.
• La figure 11 est une courbe représentant la masse de la colonne montante en fonction du jeu pour un exemple selon l'invention.
• La figure 12 représente les tenons d'une bague de verrouillage selon une variante de réalisation de l'invention.

Other features and advantages of the method according to the invention will appear on reading the following description of nonlimiting examples of embodiments, with reference to the appended figures and described below.

• The figure 1 schematically an riser according to the invention.
• The figure 2 illustrates a riser section according to one embodiment of the invention.
• The figure 3 illustrates the connection of two riser sections according to a first embodiment of the invention.
• The figure 4 illustrates an exploded view before connection of the locking ring and the female connector element according to an alternative embodiment of the invention.
• The figure 5 illustrates a locking ring according to an alternative embodiment of the invention.
• The figure 6 illustrates the connection of two riser sections according to a second embodiment of the invention.
• The figure 7 illustrates a locking ring for the second embodiment of the invention.
• The Figures 8 to 10 represent three alternative embodiments according to the invention of an auxiliary line.
• The figure 11 is a curve representing the mass of the riser according to the game for an example according to the invention.
• The figure 12 represents the tenons of a locking ring according to an alternative embodiment of the invention.

Detailed description of the invention

The figure 1 schematically a riser 1 installed at sea. The riser 1 extends the well P and extends from the wellhead 2 to a floating support 3, for example a platform or a boat. The wellhead 2 is provided with shutter commonly called "BOP" or "Blow Out Preventer". The riser 1 is constituted by the assembly of several sections 4 assembled end to end by connectors 5. Each section is composed of a main tube element 6 provided with at least one auxiliary pipe element 7, also called pipe peripheral. The auxiliary lines called "kill line" or "choke line" are used to ensure the safety of the well during the course of the procedures for controlling the inflow of fluids under pressure in the well. The "choke" line is a safety line that carries fluids (oil, water, gas) from the well during an approach and directs them to the choke manifold and the torch. The line "kill" is a safety line that allows to inject into the well heavy fluids and cements to stop an otherwise uncontrollable eruption. The auxiliary line called "booster line" allows to inject mud into the well in order to increase its speed of ascent and to avoid the sedimentation of the cuttings; it is also used to replace the sludge contained in the riser with water before disconnecting. The pipe called "hydraulic line" allows to control the shutter of the wellhead. The hydraulic lines are used to supply the safety devices of the BOPs (valves and accumulators) with hydraulic fluid (distilled water charged with glycol) under pressure.

The figure 2 schematically represents a section 4 of the riser according to one embodiment of the invention. The section 4 comprises a main tube element 6 whose axis is the axis of the riser. The auxiliary tubes 7 constitute lines or auxiliary lines arranged parallel to the axis of the main tube. The auxiliary tube elements 7 have lengths substantially equal to the length of the main tube element 6, generally between 10 and 30 meters. There is at least one line 7 disposed at the periphery of the main tube. On the figure 2 two lines 7 are schematized.

A connector 5 shown on the figure 1 consists of two designated elements, with reference to the figure 2 by the female connector element 8 and the male connector element 9. The connector elements 8 and 9 are mounted at the ends of the main tube element 6. The female connector element 8 is secured to the tube 6, for example to the by means of welding, screwing, crimping or wedging. The male connector element 9 is integral with the tube 6, for example by means of welding, screwing, crimping or a wedge connection. The assembly of the male connector element 9 with a female connector element 8 of another section forms the connector 5 which transmits forces of a riser section to the next section, in particular the longitudinal forces to which the riser is subjected. .

The connector 5 can be designed and dimensioned to meet the specifications mentioned by the API 16 R and API 2RD standards published by the American Petroleum Institute.

The figure 3 represents a male connector element 9 which is fitted into a female connector element 8. A portion of the male connector element 9 enters the female connector element 8. This engagement is limited by an axial abutment: the end of the element male connector 9 abuts against the axial shoulder formed on the inner surface of the female connector element 8: the axial shoulder formed on the outer surface of the male connector element 9 abuts against the axial shoulder formed on the inner surface of the female connector element 8. As shown in the figures 2 and 3 , the male connector element 9 may comprise a sleeve 10 fixed in the male connector element. The sleeve 10 has a role of centering and sealing male connector elements 9 and female 8. The attachment of the sleeve 10 can be performed by welding, threading, gluing, hooping or any other similar means. Instead of the sleeve 10, non-illustrated alternative embodiments may be envisaged, such as an extension of the main tube element 6 at the male connector element.

The connector 5 comprises a locking ring 11 which is mounted on the male connector element 9 and which is positioned between the main tube element 6 and the auxiliary tube element 7: the locking ring 11 is positioned on the outer surface male and female connector elements 8 and 8, and the auxiliary tube element 7 is located outside the locking ring 11. In other words, the distance between the axis of the auxiliary tube element 7 and the axis of the main tube 6 is greater than the sum of the outer radius of the locking ring 11 and the radius of the auxiliary pipe element 7. The ring 11 has a diameter smaller than the peripheral diameter (the largest diameter) of the 9 and female connector elements 8. When the male connector element 9 is fitted into a female connector element 8, a portion of the ring 11 comes into contact with the outer surface of the female connector element 8 so that a series of tenons 12 located on the inner surface of the ring 11 cooperate with a series of tenons located on the outer face of the female connector element 9. The locking and unlocking of the connector 5 are made by rotation of the ring 11 ( locking bayonet type). The ring 11 may be provided with an operating means, for example a maneuvering bar which can be dismountable. The operating bar makes it possible to rotate the ring 11. The longitudinal forces, that is to say which are directed along the axis of the main tube, are transmitted from one section 4 to the adjacent section 4 via the bayonet type connection between the ring 11 and the female connector element 8. More precisely, the longitudinal forces are transmitted from the studs 12 of the ring 11 to the tenons of the female connector element 8.

The locking ring 11 is mounted on the male connector element 9. According to the embodiment illustrated in FIG. figure 3 , the locking ring 11 comprises on its inner face another series of pins 16 cooperating with a series of tenons located on the outer face of the male connector element 9. Thus, the locking ring 11 is fixed to the connector element male, when riser sections are connected. In an unlocked situation, the ring 11 is secured to the male connector element 9 by means of pins (not shown in FIG. figure 3 ). In addition, this embodiment of the locking ring 11 allows for a completely removable connector to facilitate the inspection and maintenance of the connector. This embodiment also makes it possible to produce a ring 11 and male connector elements 9 and 8 female quasi-symmetrical, which facilitates their manufacture.

With reference to the figure 3 , the ring 11 is mounted on the outer surface of the male connector element 9. It is held by means of the series of tenons of the ring and the male and female connector elements 9 and 8. Thus, the axial forces pass from the element male connector 9 to the female connector element 8 via the teeth without passing through the sleeve 10.

The locking ring 11 is formed in one piece, in order to simplify its assembly and for better mechanical strength.

With reference to figures 3 and 4 , the female connector element 8 and the ring 11 respectively comprise a series of tenons consisting of two rings (or rows) of tenons or lugs, to ensure the axial locking of the connector 5. The tenons preferably extend in directions radials. According to a preferred embodiment, each ring (row) of tenons comprises at least four tenons. On the figure 4 , the female connector element 8 comprises a first ring 8A of four tenons and a second ring 8B of four tenons. The ring 11 also comprises a first ring 12A of four tenons and a second ring 12B of four tenons. The figure 4 represents only the lower part of the ring 11, that is to say only the part connected to the female connector element 8.

The tenons are angularly offset from one crown to the other and inscribed in cylindrical surfaces of different radii. For example, the first and second rings of the ring 11 are respectively inscribed in cylindrical surfaces of radius r and R (with r <R). The first and second rings of the female connector element 8 are respectively inscribed in cylindrical surfaces of radius r 'and R' (with r '<R'). The radius r is slightly greater than the radius R 'so that the tenons of the second ring of the female connector element 8 can slide and rotate freely inside the cylinder formed by the inner surface of the tenons of the first ring of the ring 11.

The tenons 12A of the first ring of the ring 11 cooperate with the tenons 8A of the first ring of the female connector element 8 to form a bayonet assembly. The tenons 12B of the second ring of the ring 11 cooperate with the tenons 8B of the second ring of the female connector element 8.

• la première couronne 8A de l'élément connecteur femelle 8 passe à l'intérieur de la deuxième couronne 12B de la bague 11, puis
• les tenons 8A de la première couronne de l'élément connecteur femelle 8 s'engagent entre les tenons 12A de la première couronne de la bague 11 et simultanément les tenons 8B de la deuxième couronne de l'élément connecteur femelle 8 s'engagent entre les tenons 12B de la deuxième couronne de la bague 11, puis
• lorsque la bague 11 arrive en butée, les tenons 12B de la deuxième couronne de la bague 11 se logent dans une rainure (schématisée sur les figures 3 et 4) pratiquée dans l'élément connecteur femelle 8 entre la première couronne 8A et la deuxième couronne 8B de l'élément connecteur femelle 8 et les tenons 12A de la première couronne de la bague 11 se logent dans une rainure (schématisée sur les figures 3 et 4) pratiquée dans l'élément connecteur femelle 8 sous la première couronne 8A de l'élément connecteur femelle 8.

More specifically, when the female connector element 8 is engaged in the ring 11, the female connector element 8 follows a translation movement in the direction of the axis of the main tube according to the following steps:

• the first ring 8A of the female connector element 8 passes inside the second ring 12B of the ring 11, then
• the tenons 8A of the first ring of the female connector element 8 engage between the tenons 12A of the first ring of the ring 11 and simultaneously the tenons 8B of the second ring of the female connector element 8 engage between the 12B of the second ring of the ring 11, then
• when the ring 11 comes into abutment, the tenons 12B of the second ring of the ring 11 are housed in a groove (shown schematically on the figures 3 and 4 ) made in the female connector element 8 between the first ring 8A and the second ring 8B of the female connector element 8 and the lugs 12A of the first ring of the ring 11 are housed in a groove (shown schematically on the figures 3 and 4 ) made in the female connector element 8 under the first ring 8A of the female connector element 8.

Then when the ring 11 is in abutment against the female connector element 8, the ring 11 is pivoted so that the tenons of the ring 11 are positioned facing the tenons of the female connector element. The tenons 12A of the first ring of the ring 11 are positioned facing the tenons of the first ring of the connector element female 8 and the tenons 12B of the second ring of the ring 11 are positioned opposite the tenons 8B of the second ring of the female connector element 8. Thus, the tenons of the ring 11 are in axial abutments with respect to the tenons of the female connector element 8 and translationally block the female connector element 8 relative to the male connector element 9.

Each of the two bayonet assembly systems can provide between the tenons of the female element 8 and the tenons of the ring 11 contact over a total angular range that can reach 175 °. Preferably, the two assembly systems being angularly offset around the axis of the connector, the connector according to the invention allows to distribute the axial loads about 350 ° around the axis.

Alternatively, according to the invention, the ring 11 and the female connector element 8 may each comprise only one crown: the tenons of the single ring of the ring 11 cooperate with the tenons of the single ring of the female connector element 8.

The number of tenons per ring may vary, in particular depending on the diameters of the inner tube and the forces to be transmitted by the connector.

• l'élément connecteur mâle 9 et la bague 11 comportent respectivement deux couronnes (ou rangées) de tenons ou ergots, permettant d'assurer le verrouillage axial du connecteur 5,
• les tenons s'étendent préférentiellement selon des directions radiales,
• les relations entre les rayons r, r', R, et R' sont également vérifiées afin de pouvoir insérer la bague 11 dans l'élément connecteur mâle 9,
• selon un mode de réalisation préférentiel, chaque couronne (rangée) de tenons comporte quatre tenons...

According to the embodiment shown in figure 3 , the bayonet locking system of the ring 11 in the male connector element 9 to the means of the series of tenons 16 is similar to the bayonet locking system of the ring 11 in the female connector element 8:

• the male connector element 9 and the ring 11 respectively comprise two rings (or rows) of tenons or lugs, to ensure the axial locking of the connector 5,
• the tenons preferably extend in radial directions,
• the relations between the radii r, r ', R, and R' are also verified in order to be able to insert the ring 11 into the male connector element 9,
• according to a preferred embodiment, each ring (row) of tenons comprises four pins ...

The figure 5 represents a ring 11 according to this embodiment. The locking ring 11 comprises a series of tenons 12 adapted to cooperate with a female connector element 8 to form a bayonet assembly and a series of tenons 16 adapted to cooperate with a male connector element 9 to form a bayonet assembly. Each set of tenons is composed of two crowns with four tenons. As described with reference to figure 4 , the series of tenons 12 comprises a first ring 12A and a second ring 12B cooperating with two rings of the female connector element 8. The series of pins 16 comprises a first ring 16A of tenons and a second ring 16B of tenons. Advantageously, the series of tenons 16 is similar to the series of tenons 12, and the connection of the series of tenons 16 within the male connector element 9 is identical to the connection of the series of tenons 12 within the female connector element 8. Thus , the locking ring 11 is substantially symmetrical. Thanks to this assembly, the axial forces pass from the male connector element 9 to the female connector element 8 via the teeth without passing through the sleeve 10.

In this case, for which the male connector element 9 comprises a sleeve 10, then the male connector element 9 can be symmetrical to the female connector element 8.

In the connection ring 11 with respect to the male connector element 9, there can be provided pins supporting the weight of the ring when the connection is unlocked.

A locking system makes it possible to lock the ring 11 in rotation.

According to an alternative embodiment of the invention, the bayonet assembly on the side of the male connector element comprises a separate angular connection range of the angular connection range on the side of the female connector element, so that the two connections are not simultaneous. Thus, at least one tenon, preferably all tenons, third and fourth sets of tenons protrudes over an angular range distinct from the angular range of the tenons of the first and second series of tenons. Thus, the angular range of connection of the male element is different from the angular range of connection of the female element. It is then possible to get rid of the mounting pins, because when connecting the female connector element, the pins of the male connector elements remain in contact to ensure the locking side female connector. For example, in the case of a regular distribution of the tenons on the circumference of the connection means, the bayonet assembly on the side of the male connector element comprises a distinct number of pins of the bayonet assembly on the side of the connector. female connector element.

For this embodiment of the stops may be provided to limit the rotations of the ring. For example, the stops may be made by a block integral with the locking ring and disposed on the outer surface of the locking ring, and parts protruding from the male flange, against which the block of the ring can come to bear. . Three protruding parts can be made: a first serving as locking stop, a second serving as unlocking stop of the female element, and a third serving as unlocking stop of the male element (after removing the second stop) .

According to an example of this variant embodiment, the first and second series of tenons (female connector element side) comprise at least one row of four tenons and the third and fourth series of tenons (male connector element side) comprise at least one row of three tenons. Preferably, the four pins of the connection with the female connector element extend over an angular range of about 45 ° and the three pins of the connection with the male connector element extend over an angular range of about 60 °. The figure 12 represents the inner circumference of a locking ring for such a configuration, with a first series of tenons 12, composed of two rows of four tenons having an angular range of 45 °, and the third series of tenons 16 consisting of two series three studs with an angular range of 60 °. Thus, the locking on both sides is done on 360 °. In the unlocked position, the ring rests on the male connector element by three sectors of 15 °. Turning the ring a quarter of a turn (45 °) will match all the rows of tenons (male connector element side and female connector element side). To dismantle the ring, simply make a first 15 ° rotation of the ring, slide it longitudinally until the first row of tenons is released, then make a second rotation of 60 ° in the ring. other direction to end with a longitudinal translation which releases the locking ring of the male connector element on the side of the sleeve. Alternatively, other angular ranges are possible: for example tenons respectively 15 and 20 °, tenons respectively 60 and 90 ° ...

In addition, in combination or not with the embodiment variant described above, the series of tenons can all (male connector side and female connector side) comprise the same number of rows of pins, preferably two or more.

Alternatively, the series of tenons on the side of the male connector may comprise a number of distinct rows, preferably less than the number of rows of pins on the female connector side. Thus, the design, assembly and disassembly of the locking ring and the male connector element are simplified. According to one example, the first and second series of tenons (female connector element side) comprise two rows of tenons and the third and fourth series of tenons (male connector element side) comprise a single row of tenons.

For these alternative embodiments with a number of distinct tenons on either side of the connection, it is possible, in a first step, to mount the locking ring on the male connector element by matching the studs of the ring. locking and male connector member, by means of rotation and longitudinal displacement of the locking ring relative to the male connector element. This assembly can be done at the factory or on the ground.

• rotation de la bague de verrouillage (par exemple jusqu'à une butée) de manière à conserver le verrouillage côté de l'élément connecteur mâle (secteur angulaire en contact) et à préparer la connexion du côté de l'élément connecteur femelle,
• déplacement longitudinal de l'élément connecteur mâle avec la bague de verrouillage pour insertion de l'élément connecteur femelle, et
• verrouillage de la connexion par rotation (par exemple jusqu'à une butée) de manière à ce que les tenons des deux éléments connecteurs reposent intégralement sur les tenons de la bague de verrouillage, et optionnellement sécurisation de la bague au moyen d'une broche et d'un bloc.

Then, the connection of two sections by the locking ring can be achieved by the following steps:

• rotation of the locking ring (for example up to a stop) so as to maintain the locking side of the male connector element (angular sector in contact) and prepare the connection on the side of the female connector element,
• longitudinal displacement of the male connector element with the locking ring for insertion of the female connector element, and
• locking the connection by rotation (for example up to a stop) so that the tenons of the two connector elements rest entirely on the tenons of the locking ring, and optionally securing the ring by means of a pin and of a block.

These steps can be done at sea, for example on a boat.

• déverrouillage de la connexion par rotation (par exemple jusqu'à une butée) de manière à ce que les tenons de l'élément connecteur femelle ne soient plus en contact avec les tenons de la bague de verrouillage, alors que les tenons de l'élément connecteur mâle restent en contact avec les tenons de la bague de verrouillage sur une plage angulaire,
• déplacement longitudinal de l'élément connecteur mâle avec la bague de verrouillage pour retirer l'élément connecteur femelle, et
• rotation de la bague de verrouillage (par exemple jusqu'à une butée) de manière à ce que les tenons de l'élément connecteur mâle ne soient plus en contact avec les tenons de la bague de verrouillage

For these variants with a number of distinct tenons on either side of the connection, the disconnection of two sections by the locking ring can be achieved by the following steps:

• unlocking the connection by rotation (for example up to a stop) so that the tenons of the female connector element are no longer in contact with the tenons of the locking ring, while the tenons of the element male connector remain in contact with the tenons of the locking ring over an angular range,
• longitudinal displacement of the male connector element with the locking ring to remove the female connector element, and
• rotation of the locking ring (for example up to a stop) so that the tenons of the male connector element are no longer in contact with the tenons of the locking ring

Subsequently, it is possible to disassemble the locking ring of the male connector element by longitudinal displacement of the locking ring relative to the male connector element.

According to a first embodiment of the invention (not shown), the auxiliary pipe element 7 is integrally connected at each of its ends to the main pipe 6. In other words, the riser section 4 comprises at each at its ends fixing means, which make it possible to axially link an auxiliary pipe element 7 to the main pipe 6. According to this variant embodiment, the fastening means make it possible to transmit longitudinal forces from the main pipe 6 to the auxiliary pipe elements 7 Thus, these fixing means make it possible to distribute the tensioning forces applying to each of the sections of the riser between the main tube 6 and the auxiliary pipe elements 7.

For example, at the end of the section provided with the female connector element 8, the main tube 6 is extended by a shoulder or a flange 23 having a cylindrical passage in which the auxiliary pipe element 7 can slide. The auxiliary tube element 7 comprises a stop, for example a nut or a shoulder for axially position the auxiliary tube element 7 with respect to the flange 23. When mounting the auxiliary tube element 7 on the main tube 6, the abutment of the auxiliary tube element 7 bears on the flange 23 for example against an axial shoulder formed in the cylindrical passage so as to form a rigid connection.

At the end of the section provided with the male connector element 9, the main tube 6 is extended by a shoulder or flange 24 having a cylindrical passage in which the auxiliary pipe element 7 can slide. The auxiliary pipe element 7 comprises a stop, for example a nut or a shoulder, for axially positioning the auxiliary pipe element 7 with respect to the flange 24. When mounting the auxiliary pipe element 7 on the pipe main 6, the abutment of the auxiliary pipe element 7 bears on the flange 24, for example against an axial shoulder formed in the cylindrical passage, so as to form a rigid connection.

The flanges 23 and 24 have forms of revolution around the axis of the main tube. The flanges 23 and 24 extend the main tube members 6 by increasing the thickness and the outer section of the tube, to form respectively shoulders. Preferably, the outer section of the flanges 23 and 24 varies progressively along the axis of the main tube, so as to avoid a sudden variation in section between the main tube 6 and the shoulders which would weaken the mechanical strength of the connector 5. 23, 24 flanges are arranged on either side of the locking ring 11: the spacing between the flanges 23 and 24 is greater than the height of the locking ring 11. The outer diameter of the flanges 23, 24 is greater to the diameter of the locking ring 11. According to one embodiment of the invention, the flanges 24 and 23 form one-piece pieces respectively with the male connector element 9 and the female connector element 8.

The fixing means made up of the abutments make it possible to block the axial translations of an auxiliary tube element 7 in both directions with respect to the main tube 6. Thus, the combination of the fastening means makes it possible to completely secure the auxiliary tube element. 7 with respect to the main tube element 6. Thus, the auxiliary tube elements 7 participate, together with the main tube element 6 in the recovery of the longitudinal forces applied to the column 1.

The shape and, in particular, the thickness of the flanges 23 and 24 are determined to support the longitudinal forces transmitted to the auxiliary pipe elements 7.

The elements 7 of auxiliary lines are connected end to end by means of connectors. A connector may consist of a spigot end located at one end of the auxiliary tube element 7 and a spigot end located at the other end of the auxiliary tube element 7. The spigot end cooperates with Sealed with the female end of another auxiliary tube element 7. For example, the male member of the connector is a tubular portion which fits into another tubular portion of the socket. The inner surface of the female end is fitted to the outer surface of the male end. Seals are mounted in machined grooves on the inner surface of the female member to seal the connection. The coupling allows axial displacement of one of the auxiliary tube elements 7 relative to the other, while maintaining the sealed connection between the two elements.

The auxiliary tube elements 7 may be provided with a device for compensating the differences in length between the main tube 6 and the auxiliary tube elements 7 due to manufacturing tolerances.

According to a second variant embodiment of the invention illustrated in FIGS. figures 2 , 3 , 8 at 10, the auxiliary pipe element 7 is integrally bonded with a recess connection (without relative movement between the parts) at one end of the main pipe 6 and is connected by a sliding pivot connection with the other end of the main pipe. In the present application, a sliding pivot connection designates a bond which links a first solid to a second solid, the first solid being able to translate with respect to the second solid in the direction of an axis and the first solid that can pivot relative to the second solid. around this same axis. Thus, the auxiliary pipe element 7 can slide and pivot in its axial direction relative to the main pipe 6, the auxiliary pipe element 7 is not free of movement in the radial and tangential directions, that is to say say in the directions of a plane perpendicular to the figure 3 .

In other words, the riser section 4 comprises at each of its ends connecting means, schematized on the figure 3 which on one side axially link an auxiliary pipe element 7 to the main pipe 6 and on the other side form the sliding pivot connection between the auxiliary pipe element 7 and the main pipe 6.

According to one embodiment of the invention illustrated in figure 3 the recess connection between the auxiliary pipe element 7 and the main pipe element 6 is formed at the female connector element 8, and the sliding pivot connection between the auxiliary pipe element 7 and the main pipe 6 is formed at the male connector element 9. Alternatively, the recess connection between the auxiliary pipe element 7 and the main pipe element 6 is formed at the male connector element 9, and the sliding pivot connection between the auxiliary pipe element 7 and the main pipe element 6 is formed at the female connector element 8. Only this first variant is described in the following description, the second variant being deduced by symmetry.

At the end of the section provided with the female connector element 8, the main tube 6 is extended by a shoulder or flange 23 having a cylindrical passage in which the auxiliary pipe element 7 can slide. The auxiliary pipe element 7 comprises a stop, for example a nut or a shoulder for positioning axially the element 7 relative to the flange 23. When mounting the auxiliary pipe element 7 on the main pipe 6, a stop of the element 7 bears on the flange 23, for example against the axial shoulder made in the cylindrical passage so as to form a recess connection without relative movement between the parts.

At the end of the section provided with the male connector element 9, the main tube 6 is extended by a shoulder or flange 24 having a cylindrical passage in which the auxiliary pipe element 7 can slide and pivot. The auxiliary pipe element 7 comprises a clearance adjusting means 15 (or adjustable stop) for limiting the relative movement between the auxiliary pipe element 7 and the flange 24. The clearance adjusting means 15 form a stop arranged at an adjustable distance J of the flange 24. Thus, during assembly a set J is set by the clearance adjusting means 15. Then when the riser is energized, the relative movement or the deformation of the element auxiliary pipe 7 or the main pipe element 6 is limited by a distance J, beyond a certain tension, the clearance becomes zero and the auxiliary pipe element 7 abuts in the flange 24.

The female connector elements 8 and male 9 have forms of revolution around the axis of the main tubular element. According to one possible embodiment of the invention, the flanges 23 and 24 may comprise reinforcements positioned in line with certain auxiliary lines (for example "choke line" and "kill line"). According to the invention, the connector elements 8 and 9 extend the main tube element 6 by increasing the thickness and the outer section of the tube, to form respectively the shoulders or flanges 23 and 24. Preferably, the outer section of the elements connectors 8 and 9 varies gradually along the axis 8, so as to avoid a sudden change in section between the tube 6 and the shoulders 23 and 24 which would weaken the mechanical strength of the connector 5. For example, with reference to the figure 2 , the flanges 23 and 24 form holidays.

The auxiliary tubes 7 are subjected to axial compression forces generated by the internal / external pressure difference which generates a "bottom effect" which applies to the ends of tubes (for example the auxiliary lines may be subjected to pressure of the order of 1034 bar or 15000 psi). Under these pressures, the elements of the main tube elongate and the elements of the auxiliary tubes are shortened until the clearance J is zero. When the set J becomes zero, all the lines lengthen identically. The elements of the main tube 6 are able to lengthen because they have to support all or partially, firstly the weight of the riser and the weight of the drilling mud, and secondly, the tension forces imposed on the riser to keep it substantially vertical. In general, the main tube elements at the top of the riser, that is to say close to the sea surface, undergo the maximum tension forces, so the maximum elongation. The elements of the auxiliary tubes 7 are may be shortened by the difference between the internal pressure and the external pressure due to the fluid they contain. Indeed, the fluid applies a pressure on the ends of the auxiliary tube elements 7 by imposing compression forces on the auxiliary tube elements 7. In addition, the radial deformation of the tube due to the difference between the internal pressure and the external pressure causes a shortening of the tube. In general, the elements 4 at the bottom of the riser, that is to say near the seabed, undergo the maximum internal / external pressure difference, thus the maximum shortening.

As long as the clearance J is positive, the auxiliary tube element 7 and the main tube element 6 at the same height can vary in length independently of one another. On the other hand, when the clearance J becomes zero, that is to say when the clearance adjusting means 15 is in contact with the flange 24, the auxiliary tube element 7 and the corresponding main tube element 6 form an assembly. hyperstatic: the auxiliary tube element 7 is integral with the main tube element 6 on the one hand at fastening means, and on the other hand at the stop which is in contact with the flange 24. By therefore, the main tube member 6 induces tensioning forces in the auxiliary tube member 7, and vice versa.

Thus, these connections make it possible to distribute the tensioning forces applying to each of the sections of the riser, between the main tube 6 and the auxiliary pipe elements 7. The integration according to the invention via the installation of the play J makes it possible to increase the contribution of the main tube and consequently to reduce the axial forces in the peripheral lines. The reduction of the axial forces in the peripheral lines thanks to this integration has a benefit on the dimensioning of the end pieces and on the dimensioning of the thicknesses of the auxiliary tubes.

Advantageously, the game J is chosen as a function of the length of the section, in fact the deformations of the different lines depends on the length thereof. For a typical 75 or 90 ft (22.86 m and 27.43 m) riser section, clearance J is set between 0 and 1.5 inches (0 and about 38.1 mm). Preferably, the clearance J is chosen between 0.1 and 1 inch, (2.54 and 25.4 mm) for an optimal distribution of the forces in the lines, making it possible to generate a decrease in the mass of the riser. Alternatively, the clearance J is selected between 0.1 and 0.25 inches (2.54 and 6.35 mm). Alternatively, the clearance J is selected between 0.25 and 1 inch (6.35 mm and 25.4 mm). A preferred solution with a good compromise is a clearance of about 0.5 inches (12.7 mm) or an inch (25.4 mm).

According to the invention, the clearance adjusting means 15 is made by a nut or by a threaded element. The clearance J is adjusted (before connection of the sections) as a function of the forces and pressures applied on the main tube elements 6 and the tube elements Auxiliary 7. The presence of play has a benefit on the sizing of the tips of the peripheral lines and on the sizing of the thicknesses of the peripheral lines.

The Figures 8 to 10 illustrate three embodiments of auxiliary tube element 7 equipped with game adjustment means.

According to a first variant embodiment of the game adjustment means illustrated on the figures 2 , 3 , 6 and 8 , the elements 7 of auxiliary lines are connected end to end by means of connections. A connector is composed of a male end 14 located at one end of the element 7 and a female end 13 located at the other end of the element 7. A male end 14 cooperates sealingly with the endpiece female 13 of another element 7. For example, the male end 14 of the connector is a tubular portion which fits into another tubular portion 13. The inner surface of the female end 13 is fitted to the outer surface of the the male end 14. Seals are mounted in grooves machined on the inner surface of the female end 13 to seal the connection. The connection allows axial movement of one of the elements 7 relative to each other, while maintaining the sealed connection between the two elements. The male end 14 and female 13 are fixed for example by welding or crimping to a central tube having substantially the same length as the main pipe element 6 which is attached to the auxiliary pipe element 7. For this embodiment of the invention, the invention, the game adjustment means is formed by a nut 15 positioned on the spigot end 14 on a threaded portion which is not intended to be inserted into a socket 13.

According to a second variant embodiment of the game adjustment means illustrated in FIG. figure 9 , the elements 7 of auxiliary lines are connected end to end by means of connections. A connector is composed of a male pin 18 inserted into a receptacle 17 at one end of the element 7 and a female end 13 located at the other end of the element 7. The male pin 18 cooperates sealingly with the female end piece 13 of another element 7. For example, the male pin 18 of the connector is a tubular portion which fits into another tubular portion 13. The inner surface of the female endpiece 13 is adjusted to the outer surface of the male pin 18. Seals are mounted in grooves machined on the inner surface of the female end 13 to seal the connection. The connection allows axial movement of one of the elements 7 relative to each other, while maintaining the sealed connection between the two elements. The female end piece 13 is fixed for example by welding or crimping to a central tube having substantially the same length as the main pipe element 6 to which is attached the auxiliary pipe element 7. The receptacle 17 is fixed for example by welding or crimping to the central tube. The male pin 18 is fixed to the receptacle 17 in particular by screwing. Thus, the male pin 18 is a wear part that can be changed during the maintenance of the column uplink. For this variant embodiment of the invention, the clearance adjustment means is formed by a nut 15 positioned on the male pin 18 on a threaded portion that is not intended to be inserted into a socket 13.

According to a third variant embodiment of the game adjustment means illustrated on the figure 10 , the elements 7 of auxiliary lines are connected end to end by means of connections. A connector is composed of a male pin 21 inserted into a receptacle 17 at one end of the element 7 and a female pin 19 inserted in a receptacle 20 at the other end of the element 7. The male pin 21 cooperates sealingly with the female pin 19 of another element 7. For example, the male pin 21 of the connector is a tubular portion which is inserted into another tubular portion 19. The inner surface of the female pin 19 is fitted to the outer surface of the pin 21. Seals are mounted in grooves machined on the inner surface of the female pin 19 to seal the connection. The connection allows axial movement of one of the elements 7 relative to each other, while maintaining the sealed connection between the two elements. The receptacle 20 is fixed for example by welding or crimping to a central tube having substantially the same length as the main pipe element 6 to which is attached the auxiliary pipe element 7. The female pin 19 is fixed to the receptacle 20 in particular by screwing. The receptacle 17 is fixed for example by welding or crimping to the central tube. The male pin 21 is fixed to the receptacle 17 in particular by screwing. Thus, the male pin 21 and female 19 are wear parts that can be changed during maintenance of the riser. For this embodiment of the invention, the game adjustment means is formed by the pin 21 which is threaded in the receptacle and which has a shoulder 22 providing the stop.

According to one embodiment of the invention, the auxiliary tube elements 7 are tubes shrunk by reinforcing threads, such as glass, carbon, or aramid fibers embedded in a polymer matrix. Thus, the resistance and the weight of the auxiliary lines are optimized. Indeed, the present invention is particularly suitable for the fretted auxiliary tube elements which have the advantage of reducing the thickness of steel and therefore the weight of the riser. The disadvantage of hooping to have a lower stiffness in bending is compensated by the clearance that limits the buckling of the auxiliary lines. Alternatively, the main tube and auxiliary tube elements may be composed of aluminum alloy or titanium alloy.

The device according to the invention offers an interesting solution for quickly and simply mounting a riser whose tensioning forces are distributed between the auxiliary tube elements and the main tube. Indeed, although the elements of tubes 7 and the main tube element 6 are mounted to jointly support the voltage forces applied to the column, the connection of a riser section 4 to another riser section 4 is performed in a single operation by means of the rotation of the locking ring 11. This connection makes it possible to connect and seal the main tube element 6 of a section 4 with that of the other section 4 and simultaneously to communicating and sealing the auxiliary pipe elements 7 of one of the sections 4 with those of the other section 4.

The compact connector according to the invention makes it possible to minimize the bending forces in the flanges 23 and 24, and therefore to reduce the dimensions of the flanges 23 and 24 and to reduce the weight of the connectors.

Furthermore, the fact that the ring 11 is positioned between the main tube element 6 and the auxiliary tube elements 4 makes it possible to increase the resistance of the connector. Indeed, the ring 11 holds the flanges 23 and 24 and prevents their bending. In addition, this positioning makes it possible to reduce the problem of interference of the connections of the auxiliary lines 7 because the bending moments generated by the off-axis axial forces are of opposite signs. In addition, in the locked position, the tenons of the ring 11 are engaged with the tenons of the female connector element 8 which are positioned on the solid part of the female connector element 8.

In addition, the combination of the locking ring lock and the existence of play in the connection of the auxiliary tube elements optimizes the weight of the riser.

Realization variant

According to a second embodiment of the invention, the riser section further comprises a locking ring for the connection of two consecutive sections. This locking ring is said to be external or peripheral because it cooperates with the periphery (the outermost part: with the largest diameter) of the flanges of the male and female connector elements, so as to assemble them. The auxiliary lines are therefore inside the locking ring. Thus two consecutive sections are assembled by two elements: a locking ring and a peripheral locking ring, in order to transmit the axial forces.

The figure 6 illustrates the second embodiment of the invention with a game adjustment means. The elements identical to the first embodiment are designated by the same reference signs. In the same way as for the first embodiment illustrated in particular in figure 3 , a male connector element 9 is fitted into a female connector element 8. A portion of the male connector element 9 enters into the female connector element 8. This interlocking is limited by an axial stop: the end of the male connector element 9 abuts against the axial shoulder formed on the inner surface of the female connector element 8: the shoulder axial direction formed on the outer surface of the male connector element 9 abuts against the axial shoulder formed on the inner surface of the female connector element 8. As illustrated on the figure 6 , the male connector element 9 may comprise a sleeve 10 fixed in the male connector element. The sleeve 10 has a role of centering and sealing male connector elements 9 and female 8. The attachment of the sleeve 10 can be performed by welding, threading, gluing, hooping or any other similar means. Instead of the sleeve 10, non-illustrated alternative embodiments may be envisaged, such as an extension of the main tube element 6.

The connector 5 comprises a locking ring 11 which is positioned between the main tube element 6 and the auxiliary tube element 7. When the male connector element 9 is fitted into a female connector element 8, a portion of the ring 11 comes into contact with the outer surface of the female connector element 8 so that a series of pins 12 on the inner surface of the ring 11 cooperate with a series of tenons located on the outer face of the element female connector 9. The locking and unlocking of the connector 5 are made by rotation of the ring 11 (bayonet type locking). The locking ring 11 is mounted on the male connector element 9. According to the embodiment illustrated in FIG. figure 3 , the locking ring 11 comprises on its inner face another series of pins 16 cooperating with a series of tenons located on the outer face of the male connector element 9. Thus, the locking ring 11 is fixed to the connector element male, when riser sections are connected. In an unlocked situation, the ring 11 is secured to the male connector element 9 by means of pins (not shown in FIG. figure 3 ). In addition, this embodiment of the locking ring 11 allows for a completely removable connector to facilitate the inspection and maintenance of the connector. This embodiment also makes it possible to produce a ring 11 and male connector elements 9 and 8 female quasi-symmetrical, which facilitates their manufacture.

With reference to the figure 6 , the ring 11 is mounted on the outer surface of the male connector element 9. It is held by means of the series of tenons of the ring and the male and female connector elements 9 and 8. Thus, the axial forces pass from the element male connector 9 to the female connector element 8 via the teeth without passing through the sleeve 10.

For this second embodiment of the invention, the connector 5 further comprises a locking ring 25 which is positioned on the outer (peripheral) surface of the flanges 23 and 24. The auxiliary lines 7 are therefore inside the locking ring 25. The locking ring 25 has a diameter greater than the diameter of the locking ring 11. The ring 25 can be machined in a tube portion. The ring 25 is provided at each of its ends with stops that cooperate respectively with the flanges 23 and 24 to lock in translation along the axis of the main tube the flanges 23 and 24. The locking ring 25 is rotatably mounted on the flange 24, while being locked in translation, in the direction of the axis of the main tube. With reference to the figure 6 , the ring 25 has at least one cylindrical inner surface portion of radius S and the outer peripheral surface of the flange 23 is cylindrical with a radius slightly smaller than S. The ring 25 is mounted on the flange 24 by centering the cylindrical surface inner ring on the outer cylindrical surface of the flange 24. In addition, the ring 25 has a flange which forms a radial recess of the cylindrical inner surface of the ring 25. The ring 25 rests on an axial shoulder performed on the flange 24. The inner surface of the ring 25 has tenons. The flange 23 of the female connector element also has tenons disposed on its outer peripheral surface. When the male connector element 9 is fitted into the female connector element 8, part of the ring 25 covers the flange 23 so that the lugs of the ring 25 can cooperate with the lugs of the flange 23 of the the female connector element 8.

The assembly by a peripheral ring 25 allows a high stiffness of the locking system, which limits the deformations (bending) of the flanges. In addition, the double locking ensures a capacity of the connector to transmit significant efforts. In addition, this design with double bayonet connection (male connector element side and female connector element side) makes it possible to make the connector completely removable for inspection and maintenance and also allows a quasi-symmetry of the flanges, which facilitates their manufacture. .

As illustrated on the figure 6 , the locking ring 25 further comprises a second series of tenons on its inner surface and the outer peripheral surface of the flange 24 of the male connector element 9 also comprises tenons adapted to cooperate with the tenons of the ring of lock 25.

The figure 7 represents a peripheral locking ring. The locking ring 25 comprises a first series of tenons 27 adapted to cooperate with tenons of a flange 23 of a female connector element 8 and a second series of tenons adapted to cooperate with tenons of a flange 24 of a male connector element 9.

The locking and unlocking of the connector 5 are made by rotation of the ring 25 and by rotation of the locking ring 11 (locking bayonet type). The ring 25 and the ring 11 are provided with operating means, for example a maneuvering bar which can be dismountable. The operating means make it possible to rotate the ring 25 around the flanges 23 and 24 along the axis of the main tube and, independently or simultaneously, rotate the ring 11 the axis of the main tube. To perform the simultaneous rotation of the ring and the ring, the ring 25 can be secured to the ring 11 by a rigid connection (for example by means of rods or a recessed plate avoiding any interference with the auxiliary lines when rotating the ring / ring lock assembly).

Locking and unlocking means in the locked and unlocked position of the ring / ring system may be provided, for example by means of blocks, pins, pins or screws on the flange 24 and the ring 25.

The longitudinal forces, that is to say the tension forces directed along the axis of the main tube, are transmitted from one section 4 to the adjacent section 4 on the one hand via the bayonet type connection between the ring 25 and the flanges 23 and 24 and secondly via the bayonet type connection between the ring 11 and the male connector elements 9 and female 8.

The arrangement of the connector according to the invention makes it possible to transmit almost all the forces in the main tube via the inner ring 11, while the forces in the auxiliary lines are transmitted for a part via the inner ring 11. and for the remaining part via the outer ring 25. Indeed, for this embodiment, the forces go from the flange 24 of the male connector element 9 to the flange 23 of the female connector element 8 via the pins of the ring 11 and the ring 25 without passing through the sleeve 10. The distribution of the forces between the ring 11 and the ring 25 depends on the stiffness and efforts in the lines.

The height of the ring 25 can be determined so that the distance between the lower face of the circular collar and the upper face of the studs 26, 27 is equal to the distance between the flanges 23 and 24 increased by one set at least equal to that of the inner ring 11. In addition, a space is required between the two flanges 23 and 24 to accommodate the connections 13, 14 of the auxiliary pipe tubes 7 and the game adjustment means 15. .

Openings may be made in the parts of the ring 25 located vertically and circumferentially between the tenons. These openings allow, on the one hand to lighten the room, but also and especially to see the ends of the auxiliary pipe elements 7 at the time of their connection and to avoid damage that may result from a blind approach.

According to the invention, the auxiliary pipe element 7 is integrally connected with a recess connection (without relative movement between the parts) at one end of the main pipe 6 and is connected with a sliding pivot connection with the other end of the pipe main. The figure 6 represents the second embodiment with game adjustment means. However, the second embodiment can be implemented by setting solidarily the auxiliary tube element 7 at both ends of the main tube element 6. Only this first embodiment of the second embodiment (with pivot connection is described).

It is recalled that a sliding pivot connection designates a connection which links a first solid to a second solid, the first solid being able to translate relative to the second solid in the direction of an axis and the first solid that can pivot relative to the second solid around it. of this same axis. Thus, the auxiliary pipe element 7 can slide and pivot in its axial direction relative to the main pipe 6, the auxiliary pipe element 7 is not free movement in the radial and tangential directions, that is to say -describe in the directions of a plane perpendicular to the figure 3 .

In other words, the riser section 4 comprises at each of its ends connecting means, schematized on the figure 6 which on one side axially link an auxiliary pipe element 7 to the main pipe 6 and on the other side form the sliding pivot connection between the auxiliary pipe element 7 and the main pipe 6.

According to one embodiment of the invention illustrated in figure 6 the recess connection between the auxiliary pipe element 7 and the main pipe element 6 is formed at the female connector element 8, and the sliding pivot connection between the auxiliary pipe element 7 and the main pipe 6 is formed at the male connector element 9. Alternatively, the recess connection between the auxiliary pipe element 7 and the main pipe element 6 is formed at the male connector element 9, and the sliding pivot connection between the auxiliary pipe element 7 and the main pipe element 6 is formed at the female connector element 8. Only this first variant is described in the following description, the second variant being deduced by symmetry.

At the end of the section provided with the female connector element 8, the main tube 6 is extended by a shoulder or flange 23 having a cylindrical passage in which the auxiliary pipe element 7 can slide. The auxiliary pipe element 7 comprises a stop, for example a nut or a shoulder for axially positioning the element 7 with respect to the flange 23. When mounting the auxiliary pipe element 7 on the main pipe 6, a The abutment of the element 7 bears on the flange 23, for example against the axial shoulder formed in the cylindrical passage so as to form a recess connection without relative movement between the parts.

At the end of the section provided with the male connector element 9, the main tube 6 is extended by a shoulder or flange 24 having a cylindrical passage in which the auxiliary pipe element 7 can slide and pivot. The auxiliary pipe element 7 comprises a clearance adjusting means 15 (or adjustable stop) for limiting the relative movement between the auxiliary pipe element 7 and the flange 24. The means A set clearance 15 forms a stop disposed at an adjustable distance J from the flange 24. Thus, during assembly a set J is set by the clearance setting means 15 or 18. Then when the riser is energized, the relative movement or deformation of the auxiliary pipe element 7 or the main pipe element 6 is limited by a distance J, beyond a certain tension, the clearance becomes zero and the driving element auxiliary 7 is in abutment in the flange 24.

According to the invention, the clearance adjusting means 15 is made by a nut or by a threaded element. The clearance J is adjusted (before connection of the sections) according to the forces and pressures applied on the main tube elements 6 and the auxiliary tube elements 7. The presence of play has a benefit on the sizing of the tips of the peripheral lines.

According to the embodiment variant illustrated on the figure 6 (corresponding to the embodiment of the figure 8 ), the elements 7 of auxiliary lines are connected end to end by means of connections. A connector is composed of a male end 14 located at one end of the element 7 and a female end 13 located at the other end of the element 7. A male end 14 cooperates sealingly with the endpiece female 13 of another element 7. For example, the male end 14 of the connector is a tubular portion which fits into another tubular portion 13. The inner surface of the female end 13 is fitted to the outer surface of the the male end 14. Seals are mounted in grooves machined on the inner surface of the female end 13 to seal the connection. The connection allows axial movement of one of the elements 7 relative to each other, while maintaining the sealed connection between the two elements. The male end 14 and female 13 are fixed for example by welding or crimping to a central tube having substantially the same length as the main pipe element 6 which is attached to the auxiliary pipe element 7. For this embodiment of the invention, the invention, the game adjustment means is formed by a nut 15 positioned on the spigot end 14 on a threaded portion which is not intended to be inserted into a socket 13.

Alternatively, the connections of the driving elements of the auxiliary lines are identical to those of the figures 9 and 10 .

Application example

In order to present the distribution of forces and the mass gain in a riser according to the invention, an example of application is presented.

• Profondeur d'eau : 12,500 ft (3810 m)
• Densité maximale de la boue: 14.5 ppg (1.74)
• Pression de service des lignes auxiliaires : 15,000 psi (1034 bar)
• Charge maximale de travail du connecteur : 4,000 kips (1814 t)
• Longueur des tronçons de colonne montante : 75 ft (22.86 m)
• Architecture de riser « tapered » : 7 sections d'épaisseur variable pour le tube principal.

For this example according to the figure 3 , the conditions are as follows:

• Depth of water: 12,500 ft (3810 m)
• Maximum density of sludge: 14.5 ppg (1.74)
• Auxiliary Line Service Pressure: 15,000 psi (1034 bar)
• Maximum working load of the connector: 4,000 kips (1814 t)
• Length of riser sections: 75 ft (22.86 m)
• Tapered riser architecture: 7 sections of varying thickness for the main tube.

Table 1 shows the distribution of forces in the main tube, in the auxiliary tubes: "kill line", "choke line", "booster line", "hydraulic line" according to the J-in-inch game. <i> Table 1 </ i> - <i> Distribution of forces in the riser </ i> Game J (inches) 0 0.25 0.5 1 1.5 2 2.5 Main tube 45% 50% 55% 67% 82% 97% 100% Kill line 20% 18% 16% 12% 7% 1% 0% Choke line 20% 18% 16% 12% 7% 1% 0% Booster line 7% 6% 6% 4% 1% 0% 0% Hydraulic line 4% 4% 3% 2% 1% 0% 0%

It is found that the distribution varies in the direction of a greater contribution of the main tube when the game increases. Between a zero clearance and a one-inch (25.4 mm) clearance, the distribution of forces between the main tube and the peripheral lines increases from 45% - 55% to 67% - 33%, respectively. Beyond 2 inches (50.8 mm), it is considered that there is no longer a distribution of efforts between the different lines, only the main pipe is involved in the recovery efforts, which is not desirable .

The figure 11 represents the mass M in ton of the riser as a function of the clearance J in inches for this example. For this curve, the thicknesses of the main tube and auxiliary lines have been optimized to meet the conditions mentioned above. It is found that the mass is minimal between 0 and 1 inch (25.4 mm) and a mass optimum is obtained for a 0.5 inch (12.7 mm) clearance. Beyond 1.25 inches (31.75 mm) the riser mass increases sharply, resulting in an increase in the riser cost.

In view of the distribution of the forces and the variation of the mass according to the game, the game can be adjusted between 0 and 1.25 inches (0 and 31.75 mm) for this example according to the invention. Preferably, the clearance can be adjusted between 0.1 and 1 inch (2.54 mm and 25.4 mm). Optimally, the clearance can be adjusted to 0.5 inch (12.7 mm).

Claims (22)

1. A riser section comprising a main tube element (6) extended by a male connector element (9) and by a female connector element (8), wherein a locking ring (11) is mounted on said male connector element (9), and wherein said riser section further comprises at least one auxiliary tube element (7), said male (9) and female (8) connector elements extending main tube element (6) by increasing the section and the thickness of said main tube element (6) so as to form flanges (23, 24) for passage of said auxiliary tube element (7), characterized in that said locking ring (11) is arranged between said main tube element (6) and said auxiliary tube element (7), the inner surface of said locking ring (11) comprises a first series of studs, the outer surface of said female connector element (8) comprises a second series of studs, said male connector element (9) comprises a third series of studs on the outer face thereof and the inner surface of said locking ring (11) comprises a fourth series of studs (16) suited to cooperate with said third series of studs.
2. A section as claimed in claim 1, wherein at least one stud of the third and fourth series of studs protrudes over an angle range distinct from the angle range of the studs of the first and second series of studs.
3. A section as claimed in claim 2, wherein each row of the first and second series of studs comprises a number of studs distinct from the number of studs of each row of the third and fourth series of studs.
4. A section as claimed in claim 3, wherein the first and second series of studs comprise at least one row of four studs, and the third and fourth series of studs comprise at least one row of three studs.
5. A section as claimed in any one of the previous claims, wherein the first and second series of studs comprise a number of rows distinct from the number of rows of the third and fourth series of studs.
6. A section as claimed in claim 4, wherein the first and second series of studs comprise two rows of studs, and the third and fourth series of studs comprise one row of studs.
7. A section as claimed in claim 1, wherein each series of studs consists of at least two rows of at least four studs.
8. A section as claimed in any one of the previous claims, wherein a sleeve (10) is secured within said male connector element (9), said sleeve (10) being suited to cooperate with female connector element (8) so as to form a sealed link.
9. A section as claimed in any one of the previous claims, wherein said riser section comprises a locking collar (25) cooperating with the peripheral surfaces of said flanges (23, 24) for assembling said flanges (23, 24).
10. A section as claimed in claim 9, wherein the inner face of said locking collar (25) is provided with a first series of studs and the peripheral surface of flange (23) of said female connector element (8) comprises a second series of studs.
11. A section as claimed in claim 10, wherein the inner face of said locking collar (25) is provided with a third series of studs and the peripheral surface of flange (24) of said male connector element (9) comprises a fourth series of studs suited to cooperate with said third series of studs.
12. A section as claimed in any one of the previous claims, wherein said auxiliary tube element (7) is a hooped steel tube with reinforcement wires such as glass, carbon or aramid fibers, coated with a polymer matrix.
13. A section as claimed in any one of the previous claims, wherein said auxiliary tube element (7) is secured to the two flanges (23, 24) of said male (9) and female (8) connector elements.
14. A section as claimed in any one of claims 1 to 12, wherein said auxiliary tube element (7) is secured to a flange of said male (9) and female (8) connector elements and it is connected by a sliding pivot connection to the other flange of said male (9) and female (8) connector elements, said sliding pivot connection allowing a relative translational motion between said main tube element (6) and said auxiliary tube element (7) over a distance limited by a clearance adjustment means (15, 18) arranged on said auxiliary tube element (7).
15. A section as claimed in claim 14, wherein said clearance adjustment means consists of a nut (15) or a threaded part (18).
16. A section as claimed in claim 15, wherein said auxiliary tube element (7) is extended on the one hand by a female end piece (13) and on the other hand by a male end piece (14) provided with a nut (15).
17. A section as claimed in claim 15, wherein said auxiliary tube element (7) is extended on the one hand by a female end piece (13) and on the other hand by a receptacle (17) in which a male pin (18) provided with a stop (15) is inserted.
18. A section as claimed in claim 15, wherein said auxiliary tube element (7) is extended on the one hand by a receptacle (20) in which a female pin (19) is inserted and on the other hand by a receptacle (17) in which a male threaded pin (21) is screwed, said male threaded pin comprising a shoulder (22).
19. A section as claimed in anyone of claims 14 to 18, wherein said distance limited by said clearance adjustment means (15, 18) ranges between 0 mm and 31.75 mm, preferably between 2.54 mm and 25.4 mm.
20. A riser comprising at least two riser sections (4) as claimed in any one of the previous claims, for which connection between two consecutive sections (4) is achieved by means of said male (9) and female (8) connector elements and of said locking ring (11).
21. A riser as claimed in claim 20 comprising at least two sections (4) as claimed in any one of claims 14 to 19, wherein said distance of the relative translational motion of said sliding pivot connection is adjusted so as to be positive upon connection of at least two sections (4) of said riser and to be zero while using said riser.
22. Use of a riser as claimed in any one of claims 20 or 21 for carrying out an offshore drilling operation.

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