FR2863030A1 - Tubular joint, e.g. for hydrocarbon casing, has lip extending male thread and curved seating on female threaded part, so that after plastic deformation by radial expansion, joint becomes sealed - Google Patents

Abstract

The second and third butting surfaces are respectively convex and concave, at the same angle to the longitudinal axis of the tube, so they press together to give a sealed radial grip between the first internal surface and second external surface. The first external surface and third internal surface are constrained to give a local sealed grip when radial expansion causes plastic deformation : A first tubular element (EM) has a first part with a male thread and a second part (P2) extending the first part and including a first annular lip (L1) with a first axially butting surface (SB1), a first internal surface and a first external surface, and a second butting surface (SB2). A second tubular element (EF) has a female thread matching the male thread and screwing onto it, a second annular lip (L2) with a third butting surface (SB3) pressing against the second butting surface, a second external surface placed opposite the first internal surface and a second internal surface, a fourth butting surface (SB4) and a third internal surface facing the female thread and defining with the second external surface and the fourth butting surface an annular seating (LO) for the first lip. The angles are initially between 5 and 30[deg]. The first and second lips are shaped so the first internal surface and the second external surface do not make a gripping contact until after the second and third butting surfaces. The first butting surface is designed to press against the fourth butting surface during tightening in a way which provokes axial compression of the first lip in elastic deformation. The second external surface of the second lip has an inclined annular portion at the level of contact with the third butting surface, at an angle of between 8 and 12[deg], preferably 10[deg]. The first internal surface of the first lip is inclined at an angle of between 0.1 and 15[deg]. The male and female threads have threads with a bearing flank with a negative angle of between -3 and -15[deg]. and an engaging flank with a positive angle of between +10 and +30[deg]. The threads are designed after screwing and before deformation to leave an axial play between their engaging flanks of between 0.1 and 0.3mm. The first tubular element has at the level of its first external surface and before its first part, a conical chamfer defining a local annular seat inwards. This chamfer has a continuous slope of between 8 and 12[deg]. A second part of the first tubular element has a local annular over- thickness at the level of a fourth internal surface extending the second butting surface in the direction of the first part, and a third internal surface with a groove in a selected place in which the local over- thickness will fit. At the level of the first external surface of the first lip, during radial expansion, an annular shoulder matching at least part of the groove is in gripping and sealing contact with the groove. The groove has two curvilinear portions with identical radii of curvature of between 2 and 20mm, separated by a cylindrical central part. An independent claim is made for a process to make the above joint by screwing the parts together and then expanding them radially using an axially displaced expansion tool.

Description

REALIZATION, BY PLASTIC EXPANSION, OF A TUBULAR SEAL WITH

SURFACE (S) OF INCLINED STOP (S)

  The invention relates to the field of tubular joints, such as those used in hydrocarbon wells or similar wells such as geothermal wells.

  These seals are generally used to connect together long tubes or long tubes and sleeves. They thus make it possible to form columns of casing (or "casing") or production (or "tubing") tubes.

  In addition, these seals must withstand high bending, tensile, compressive, and sometimes twisting stresses, as well as large pressure differences between the inside and the outside. In addition, these seals must sometimes also be gas tight. For these reasons, the seals are frequently of the threaded type and the sleeves and tubes are generally made of steel or alloy with high elasticity limits (possibly obtained by heat treatments). In the case of threaded joints, the gastightness is most often provided by sealing surfaces with metal-on-metal contact.

  In order to reduce the initial bulk of the tubes, as well as possibly allow the drilling of wells of uniform diameter, it has been proposed, in particular in the documents US 6,604,763 and WO 03/071086, to expand them diametrically with force in situ at the same time. using an expansion tool called "ball". Sealed threaded joints, such as those described in EP 0488912, can withstand such expansion but lose their sealing characteristics during expansion, the nose at the end of the male element which carries a sealing surface male diving towards the axis during expansion (effect "banana"), which breaks the seal.

  To solve this problem, the Applicant has proposed in WO 02/01102 a threaded tubular seal whose male nose is provided at the end of an annular finger embedded in a female groove, the groove forming a support for the finger and preventing the dive of the male finger towards the axis, during the expansion.

  Such a threaded joint, however, does not have sufficiently high sealing characteristics when the expansion ratio is greater than 10%. Indeed, the deformations induced by the expansion ball move or even suppress the contacts between the male finger and the groove, which moves, reducing or even eliminating them, the sealing contacts between sealing surfaces .

  By "tight contact" is meant here a contact developing a contact pressure between two surfaces in contact. The higher the contact pressure, the greater the fluid pressure that the seal can withstand without breaking the seal. In addition to the fluid pressure, which may be exerted inside or outside the threaded joint, axial tensile or compressive loads may change the contact pressure, and hence the sealing characteristics. In other words, because of the embodiment of these seals their sealing may not be identical vis-à-vis the internal pressure or the external pressure, nor be stable depending on the load.

  In order to improve the situation, the Applicant has proposed, in patent document FR 02/03842 (filed March 27, 2002, under internal priority of the patent document FR 02/00055 filed January 3, 2002), a tubular sealing gasket. metal / metal provided with an annular finger (or lip), described in WO 02/01102 and having inclined male and female shoulders, strongly tightened against each other after expansion, the shoulder on the element female being constituted by the flank of a groove, and the shoulder on the male element may pre-exist or result from the printing of the male element at the bottom of the groove during the expansion.

  This seal has been designed to be tight at high expansion rates, typically greater than 10%, but its sealing characteristics may be insufficient when the sealing characteristics required in the various loading modes are high.

  The invention therefore aims to improve the situation, particularly in terms of stability of the high pressure gas seal, before and after expansion, for the various modes of loading.

  It proposes for this purpose a sealed tubular seal comprising: a first tubular element comprising, on the one hand, a first part provided with a male thread, and secondly, a second part extending the first part, comprising a first annular lip, having a first axial abutment surface, a first internal surface and a first external surface, and a second abutment surface, * a second tubular element having, firstly, a female thread, homologous to the thread male and screwed thereon, a second part, a second annular lip, having a third abutment surface bearing against the second abutment surface, a second external surface, placed opposite the first internal surface, and a second internal surface intended to cooperate with the first external surface, of a third part, a fourth axial abutment surface, and a fourth part, a third surface internal opposite to the female thread and defining with the second outer surface and fourth abutment surface an annular housing homologous to the first lip.

  This seal is characterized in that the second and third abutment surfaces have respectively convex and concave conical surfaces and inclinations of substantially identical angles with respect to a plane transverse to a longitudinal direction, and chosen so as to form a support of the second abutment surface against the third abutment surface of such a nature as to induce a tight radial clamping of the first internal surface against the second external surface, and such that, during a diametral expansion in the field of plastic deformation carried out subsequently on the initial tubular joint, the first outer surface and the third inner surface to locally define a tight and tight contact.

  In this way, a quality seal is provided by cooperation of the first and second lips, before and after expansion, including for high diametric expansion rates (up to about 35%).

  The seal according to the invention may comprise other characteristics which may be taken separately or in combination, and in particular: the inclinations of the second and third abutment surfaces may initially be between approximately +5 and approximately +30; the curvature of the first lip towards the longitudinal axis of the joint makes it possible, during the expansion, to define a tight and tight contact between their first internal surface and the second external surface once the second abutment surface has resting on the third abutment surface, the first abutment surface may be arranged to abut against the fourth abutment surface and thereby cause axial compression of the first lip in the field of elastic deformations. the second lip may comprise a second external surface initially having, at its connection with the third abutment surface, a port annular ion inclined relative to the longitudinal direction by an angle of between about 8 and about 12, and preferably equal to about 100-the first lip may comprise a first internal surface initially inclined with respect to the longitudinal direction of a angle between about 0.1 and about 15, the ratio between the extension of the second lip in the longitudinal direction and the extension of the housing in the transverse direction can be between about 1 and about 3, and preferably included between about 1.2 and about 1.6, the male and female threads may comprise threads provided with a load flank having a negative angle of between about -3 and about -15, the male and female threads may comprise threads having an engagement flank having a positive angle of between about +10 and about +30, in which case the male and female threads may screwing and before expansion an axial play between. their engagement flanks of between approximately 0.1 mm and approximately 0.3 mm, the first tubular element may initially have at its first external surface and before its first part a conical chamfer defining a local annular recess towards the first inside, when one moves towards the first part. In this case, the chamfer may have a substantially continuous slope relative to the longitudinal direction and between about 8 and about 12, - the first tubular element may be provided with a second portion initially having a local annular extra thickness selected at the level of a fourth inner surface extending the second abutment surface towards the first portion, and a third inner surface having at a selected location a throat adapted to be placed after screwing substantially at the local extra thickness. In this case, the first outer surface of the first lip may comprise after the diametrical expansion an annular shoulder which has at least part of the conformation of the groove and in tight and tight contact therewith, the first tubular element may initially have at its first part, on the opposite side to the male thread, a tapered necking in which is defined a local annular recess. In this case, the necking can initially increase substantially continuously along a slope with respect to the longitudinal direction A, of between approximately 2 and approximately 20; the groove may initially comprise at least two curvilinear portions, possibly separated by a central portion. substantially cylindrical. In this case, the portions may initially have substantially identical radii of curvature, for example between about 2 mm and about 20 mm. The groove initially has a radial depth, the maximum value of which is preferably chosen so that the groove bottom material section is greater than the product of the smallest section of a running portion of the tubes to which the first and second grooves belong. tubular elements by the effectiveness of the joint in traction. The term "common part of a tube" means the central part distant from its two ends and of substantially constant diameter, the male and female threads are preferably chosen from the threads of the conical and cylindrical type, and are each formed on at least one tubular element portion. said second tubular element may belong to a substantially symmetrical connection sleeve of the female / female type and said first tubular element to one end of a tube of great length. The sleeve may then comprise a central portion extended on either side by two second tubular elements and initially provided on an outer face with an annular zone having a sub-thickness selected so that the initial thickness of said sleeve at this zone is greater than or equal to the product of the section of a current portion of the tubes, at the ends of which are formed said first tubular elements, by the effectiveness of the seal.

  The invention also relates to a method for producing a threaded tubular joint from an initial tubular joint of the type shown above.

  In this process, it is possible to start from first and second shaped lips chosen so that the first inner surface and the second outer surface only establish a close contact 10 after the second abutment surface has been pressed onto the third surface of the second surface. stop.

  Furthermore, the screwing may first force the first abutment surface to abut against the fourth abutment surface so as to cause an axial compression of the first lip in the field of elastic deformations.

  Such a method is particularly well suited, although in a non-limiting manner, to the radial expansion of the joint according to an expansion ratio of at least 10%.

  Other features and advantages of the invention will be apparent from the following detailed description and the accompanying drawings, in which: Figure 1 schematically illustrates, in a longitudinal sectional view, a Part of an exemplary embodiment of a sealed threaded joint according to the invention, Figure 2 schematically illustrates, in a longitudinal sectional view, a portion of a conical female thread and the homologous conical male thread before 2 Figure 3 schematically illustrates, in a longitudinal sectional view, a portion of the male end of the first tube of the sealed threaded joint of Figure 1, Figure 4 schematically illustrates, in FIG. a longitudinal sectional view, a portion of the female end of the second tube of the sealed threaded joint of FIG. 1, FIG. 5 schematically illustrates, in a longitudinal sectional view, the forces generated. on the male and female ends of the tubes of FIGS. 3 and 4 during the first screwing step, FIG. 6 schematically illustrates, in a longitudinal sectional view, the forces generated on the male and female ends of the tubes of FIGS. and 4 during the second screwing step, Figure 7 schematically illustrates, in a longitudinal sectional view, the forces generated on the male and female ends of the tubes of Figures 3 and 4 during the expansion step by FIG. 8 schematically illustrates, in a longitudinal sectional view, the deformations experienced by the male and female ends of the tubes of FIGS. 3 and 4 after the expansion step, and FIG. schematically, in a longitudinal sectional view, a portion of an embodiment of an assembly of two threaded joints according to the invention, arranged symmetrically.

  The attached drawings may not only serve to complete the invention, but also contribute to its definition, if any.

  The invention relates to a tight threaded tubular joint, which can be used in particular in a hydrocarbon well or in a similar well such as a geothermal well, and the associated production method.

  As indicated in the introduction, a threaded tubular joint according to the invention can make it possible to form columns of casing or production tubes, by assembling metal tubes of great length between them or else of tubes of great length and sleeves.

  Referring first to Figures 1 to 8, a first embodiment of a seal according to the invention is described. In this example, as partially illustrated in FIG. 1, the seal makes it possible to connect two tubes Ti and T2, of axis of revolution XX and of great length, that is to say several meters in length, and more precisely the end of the male type EM (or male tubular element) of a first tube Ti and the end of the female type 2 5 EF (or female tubular element) of a second tube T2. In the illustrated embodiment, the tubes Ti and T2 have, for example, a running portion whose initial outside diameter is equal to about 193.68 mm (or 7 "5/8) .The current portion of a tube is the portion central distant from both ends and of substantially constant diameter.

  As illustrated in FIG. 1, the male end EM of a tube T1 has two parts P1 and P2. The first part P1 extends the central part of the tube T1 and is provided with an external male thread FM, preferably of conical type, but it could also be cylindrical type.

  For example, as illustrated in FIG. 2, a tapered thread is provided whose taper AD / D, where D is the diameter, is 10%. Furthermore, the axial play (or longitudinal) between the nets is initially large enough to offer them a certain freedom of movement during the diametric expansion, which will be discussed later. For example, the axial clearance between the flanks of engagement (or "flank stabbing") FS of the threads of the male threads FM and female FF is between about 0.1 mm and about 0.3 mm.

  In addition, in order to ensure a good tensile strength, but especially in compression, and therefore to reduce the risk of disengagement or defloration of the male and female threads before, during and after expansion, the carrier flank (or "flank" loading ") FL of the threads is inclined, for example, with respect to the radial direction of a negative angle α between about -3 and about -15 and more preferably about -10, while the engagement flank FS of the threads for example, is inclined with respect to the radial direction of a positive angle a2 between about +10 and about +30, and more preferably about +15.

  The negative angle α makes it possible to avoid the disengagement or de-meshing of the threads in engagement, in particular under tension. On the other hand, the larger the positive angle a2, the easier the engagement of the threads is, but the more the compressive strength is degraded.

  It is important to note that the male FM and female FF threads can each be formed on at least one tubular element portion EM, EF. In other words, they can be made in one or more parts. When they consist of two parts they can be optionally formed on two radially distinct surfaces or alternately on the same surface.

  The second part P2 extends the first part P 1 to the end of the tube T 1. It comprises first of all, as illustrated in FIG. 3, a first annular lip (or annular finger) L1 comprising a first axial abutment surface. SB1, initially substantially flat and perpendicular to the longitudinal axis A of the tube Ti (parallel to XX), a first internal surface SI1, initially extending substantially perpendicularly to the first axial abutment surface SB 1 towards the first part P1 and oriented towards the inside of the tube Ti (that is to say on the opposite side to the male thread FM), and a first external surface SE1, also extending the first axial abutment surface SB1 towards the first part P1 and oriented towards the outside of the tube Ti. It further comprises a second stop surface SB2 extending the first internal surface SI1 and extended by a (fourth) internal surface SI4 at least partially cylindrical and intended to be in contact with the fluid (or gas) flowing in the tube T1. first axial abutment surface SB1, first inner surface SI1 and second abutment surface SB2 define what one skilled in the art calls a "male rabbet".

  As illustrated in FIG. 3, the first internal surface SI 1 can be inclined at an angle a3 chosen with respect to the longitudinal direction A of the tube T1, for a reason which will be mentioned below. It thus initially forms a conical surface. The angle of inclination is preferably between about 0.1 and about 15, and more preferably about 2.5. Moreover, as illustrated, the first outer surface SE 1 may be slightly curved, and more precisely toric with a large radius, for example between 20 mm and 100 mm, in order to facilitate its printing in a groove G1, as will be seen later. .

  As illustrated in FIG. 4, the female end EF of a tube T2 also comprises two parts P3 and P4. The first part P3, placed most at the end of the tube T2, is provided with an internal female thread FF homologous to the male thread FM.

  The second portion P4 extends the first portion P3 to the central portion of the tube T2. It first comprises a second annular lip (or annular finger) L2 comprising a third abutment surface SB3, a second external surface SE2 facing outwardly of the tube T2, extending the third abutment surface SB3 in an opposite direction. at the first portion P3 and intended to be placed facing the first internal surface SI1, and a second internal surface SI2 at least partly cylindrical, facing the inside of the tube T2 (that is to say on the opposite side to the female thread FF) and also extending the third abutment surface SB3 in a direction opposite to the first part P3.

  It further comprises a fourth axial abutment surface SB4, initially substantially planar and perpendicular to the longitudinal direction A of the tube T2, and a third internal surface SI3 partly cylindrical, facing the inside of the tube T2 and extending the fourth axial abutment surface SB4 towards the first part P3. A portion of the third inner surface SI3 together with the second outer surface SE2 and the fourth abutment surface SB4 define an annular housing (or groove) LO homologous to the first lip L1 so as to receive it during the screwing phase of the T1 and T2 tubes, which will be discussed later.

  The housing LO extends over a selected axial length PR, equal to that of the second lip L2, and a selected radial depth H (perpendicular to the longitudinal direction A). Preferably, the ratio PR / H is between about 1 and about 3, and more preferably between about 1.2 and about 1.6. It is even more preferably equal to about 1.5. For example, PR is 4 mm and H is 2.7 mm, which provides a PR / H ratio substantially equal to 1.5. As will be seen below, these two dimensions PR and H are chosen so as to allow a selected deformation of the first lip L1.

  The third abutment surface SB3, second outer surface SE2 and fourth axial abutment surface SB4 define what one skilled in the art calls a "female rabbet". 0 (

  An annular groove G1 is further defined in at least a portion of the third internal surface SI3. It initially comprises, preferably, a substantially cylindrical PC central portion and extended on either side by two curvilinear portions PC1 and PC2. These curvilinear portions C1 and C2 initially have, preferably, substantially identical radii of curvature, preferably between about 2 mm and about 20 mm. But, this groove G1 could have only two curvilinear portions.

  For example, the groove G1 comprises a central part PC which extends over an axial length PR 'equal to approximately 2 mm, a radial depth H' equal to approximately 1 mm, and curvilinear portions C1 and C2 which have a radius of curvature equal to about 5 mm. The radial depth H 'of the groove G1 is generally limited by the thickness of the tube T2, at the plane of symmetry PSG of said groove, which must not be less than a minimum thickness for calculating the critical section of the joint threaded. More precisely, the maximum value of the radial depth H 'is chosen so that the cross-section of material at the bottom of the gro G1 is greater than the product of the section of the tube Ti or T2 in its running portion (or of the lowest of these two sections if they are different) by the efficiency of the joint in tension. The ratio between the critical section of the threaded elements and the tube section (T1, T2) characterizes the efficiency of the connection (or joint), which is with the section of the tube an input data of the design of a tubular column.

  In this configuration, the PSG symmetry plane of the groove G1 is placed at a selected axial distance D of the fourth axial abutment surface SB4 which defines the bottom of the housing (or groove) LO. For example, with the aforementioned values, the distance D is equal to about 5.61 mm. Furthermore, after screwing, the central part PC of the groove G1 is substantially placed in line with the excess thickness SA1.

  As will be seen below, the radius of curvature (in particular on the thread side), the radial depth H ', the axial length PR and the radial depth H are chosen so as to allow the selected deformation of the first lip L1 in cooperation In particular with the second SB2 and third SB3 abutment surfaces.

  The second part P4 also comprises another (fifth) internal cylindrical surface C11 extending the second abutment surface SB2 in the direction opposite to the first part P3 (that is to say towards the central part of the tube T2) and intended to be in contact with the fluid (or gas) circulating in the tube T2.

  According to the invention, the second abutment surface SB2 and the third abutment surface SB3 initially have respectively convex and concave conical surfaces and o (inclinations of angles a4 chosen with respect to a plane perpendicular to the longitudinal direction A, substantially identical.

  Preferably, as illustrated in FIGS. 3 and 4, the second SB2 and third SB3 abutment surfaces have substantially the same initial inclination. Here, the term "substantially equal inclinations" inclinations equal to about 5. This common slope is preferably between an angle a4 of about +5 and an angle a4 of about +30. It is more preferably still equal to about 10.

  This inclination makes it possible, when the second abutment surface SB2 bears against the third abutment surface SB3 during the screwing phase, to radially prestress the first lip L1 in the direction of the axis of the seal and thus to tighten radially, and sealingly, its first inner surface SI1 against the second outer surface SE2 of the second lip L2 (due to their respective chosen shapes). It furthermore makes it possible, as will be seen below, to constrain the first external surface SE I and the third internal surface SI3 (due to their respective chosen shapes) to locally define a tight and tight contact, during the phase of diametric expansion in the field of plastic deformation.

  The formation of a seal according to the invention is carried out by the implementation of a method comprising the following steps.

  In a first step illustrated in FIG. 5, the end, for example male EM, of one of the tubes, for example T1, is screwed onto the end, for example female EF, of the other tube. for example T2, until the first axial abutment surface SB1 of the first lip L1 is based on the fourth axial abutment surface SB4 of the housing (or groove) LO.

  In order to facilitate this screwing, and as illustrated in FIG. 4, the second outer surface SE 2 of the second lip L 2 may have, for a short distance, an inclination of an angle 30 selected a 5 with respect to the longitudinal direction A, at the its connection with the third thrust surface SB3. It thus initially forms a conical surface chamfer. Preferably, this inclination is initially between an angle of about +8 and an angle of about +12. More preferably still, it is equal to about 10. Such inclination facilitates the penetration of the first lip LI into the housing (or groove) LO, particularly in the case of accidental interference, which reduces the risk of seizing or damage to the first lip L1 , and in particular of the end edge of its first internal surface Sil. Such interference can indeed occur between the first inner surface SI1 and the second outer surface SE2 before the second abutment surface SB2 rests on the third abutment surface SB3.

  Then, in a second step is continued screwing until the second abutment surface SB2 of the first lip L1 is based on the third abutment surface SB3 of the second lip L1. The pursuit of the screwing, after the abutment of the first abutment surface SB1 on the fourth abutment surface SB4, makes it possible to initiate the storing of elastic potential energy in the first lip L1, by putting it into compression axial.

  In a third step illustrated in FIG. 6, screwing is continued in order to radially prestress the first lip L1 in the direction of the axis of the joint, thanks to the inclination (or slope) of the second SB2 and third SB3 surfaces. stop SB3 of the first L1 and second L2 lips, and the cooperation of the first SB1 and fourth SB4 axial abutment surfaces. This prestress is shown by the arrows F1 and F2 in FIG.

  The contact between the different abutment surfaces and the two lips is thus substantially reinforced, which makes it possible to seal the seal before the diametric expansion step.

  Thus, before expansion, an excellent gas tightness under internal pressure is obtained, even in the presence of tensile or axial compression forces, and a good seal under external pressure, even in the presence of axial compressive forces.

  In a fourth step, a diametral expansion tool is introduced axially into one of the tubes T1 and T2, for example a conical ball whose maximum diameter is greater than the initial internal diameter DI of the tubes T1 and T2 (equal to to 2 times the internal radius RI materialized in Figure 1) and is substantially equal to their final internal diameter. The choice of introduction direction is not really important. Therefore, the ball can be moved axially from a male end EM to a female end EF, or vice versa.

  The movement of the ball is carried out in a manner known to those skilled in the art (see in particular the documents US 6,604,763 and WO 03/071086), for example by pulling with the aid of drill rods or by exerting pressure hydraulic. The ball has for example a cylindro-conical shape with a conical inlet portion responsible for effecting expansion and extended by a central cylindrical portion. But, its shape can also be spherical or biconical (conical input portion extended by a cylindrical portion, itself extended by a conical exit portion). The connecting radii of these three parts of the ball are chosen according to the needs. at

  Other expansion tools may be used in place of the balls, such as a rotary expansion tool with three rollers performing a mechanical expansion. These expansion tools (including the balls) and their modes of use are described in particular in patent documents WO 02/081863, US 6,457,532 and US 2002/0139540.

  Diameter expansion occurs in the field of plastic deformations. As the plastic deformations generated increase the elastic limit of the tubular elements, it is therefore necessary to use metals that support such deformations. For example, a tube initially having a yield strength of 310 MPa (45 KSI) sees this limit increase to 380 Mpa (55 KSI) after expansion.

  When the ball reaches the level of the fourth internal surface SI4 of the second portion P2 of the male end EM and the fifth internal surface SI5 of the second portion P4 of the female end EF, the expanded material constrains the first lip L1 to deform in the throat G1. The deformations experienced by the joint during the expansion are represented by the arrows F3 to F6 in FIG.

  More specifically, the first lip L1 is forced to bend (arrow F4) and take at least partly the shape of the groove G1. It is then created, as illustrated in FIG. 8, at the level of the first external surface SE1 of the male end EM, just before the first lip L1, an annular shoulder or heel EP which makes it possible to create a sealing zone by tight contacts of type "metal on metal".

  The shoulder EP and the seal may be reinforced by the presence of a local annular thickening SA1 in the direction of the inside of the tube Ti, at the level of the fourth internal surface SI4 of the first lip L1 and in the vicinity of the second stop surface SB2. Preferably, as illustrated in FIGS. 3 and 5 to 7, this excess thickness SA1 is substantially constant in the zone of extension of the central portion PC of groove G1, and then decreases. This decrease is preferably substantially continuous in the direction of the first portion P 1. It can for example be made at an angle a9 with respect to the longitudinal direction A of between about 5 and about 30, and more preferably between about 10 and about 20, and even more preferably equal to about 12.

  The maximum thickness at the region of constant thickness defines a minimum inside diameter of the male element EM. This inner diameter must be greater than the diameter of a buffer (called "drift" by the skilled person). The buffer (or drift) is a tool that is introduced inside the tubes, before going down into the wells, to ensure that they have a minimum internal free diameter guaranteeing the passage of tools in the column without risk of snagging. When it remains below the value

K

  mentioned above, the optimum value of the extra thickness is then fixed by the amount of material necessary to make the first lip L1 rise to the maximum in the bottom of the GI groove during the expansion so that it deforms according to the needs . For example this extra thickness is equal to about 0.8 mm.

  Sa1 extra thickness offers a surplus of material that can fill the empty space of the groove G1, and therefore allows the first lip L1 and the area just before it to take the conformation of at least a portion of said groove G1, and therefore to present substantially the desired deformation.

  The deformation generates, as indicated above, the shoulder or annular heel EP, at the first outer surface SE1 of the male end EM, before the first lip L1, which makes it possible to create a contact sealing zone. tightening as indicated below.

  The expansion carried out by the ball results, because of the diameter of the female element EF greater than that of the male element EM, by an expansion rate of the male element EM larger than that of the EF female element.

  As a result of the preservation of the material, contraction of the male element EM is greater than that of the female element EF, which results in a relative axial displacement of these two elements in the direction of a clearance materialized by the arrows F5 and F6 of Figure 7. This movement tightly press the one against the other inclined shoulders EP, creating the targeted seal. It can be noted that the contact or clamping pressure is further increased when the seal is subjected to axial tensile stresses.

  Due to the axial disengagement during expansion, the axial lengths of the first L1 and second L2 lips must be chosen accurately. Indeed, if the first lip L1 is too short, it may exit its housing LO and thus plunge towards the axis of the joint, thus eliminating the seal after expansion. If the second lip L2 is too long, the housing LO is difficult to machine.

  The curvature of the first lip L1 during expansion, favored by the shape of the groove G1 and the excess thickness SA1, results in a second clamping contact between the inner part of the end of the first lip L1 and the second outer surface SE2.

  The first lip L1 is then braced and wedged between the shoulder formed in the wall of the groove G1 and the second outer surface SE2. Such a double contact makes it possible to ensure excellent, stable sealing for the various possible loading modes, comprising both the internal and external pressure combined or not with traction or axial compression forces.

  In order to further promote the curvature of the first lip L1 and further strengthen the contact between the shoulder or heel EP and the groove G1, it is possible, as illustrated in FIGS. 3 and 5 to 7, to provide a recess DC1 towards the inside the tube Ti, at the first external surface SE I and before the first part P 1. This recess DC 1 is preferably substantially continuous. It thus initially constitutes a conical chamfer. It may for example be at an angle a6 to the longitudinal direction A, between about 8 and about 12, and more preferably about 10. For example, this recess DC 1 starts at a distance from the first axial abutment surface SB1 (along the longitudinal direction A) equal to about 7.8 mm.

  Moreover, in order to dispose of material where it is necessary, the tube Ti may undergo at its first P1 and second P2 parts, and before machining the male element EM, a tapered recess of half-angle at the top a7 , the diameter of the cone decreasing when moving towards the free end of the male element EM.

  This shrinkage makes it possible to increase the thickness of material at the level of the second portion P2 and to accommodate the excess thickness SA1. After machining the male element EM and in particular the excess thickness SA1, the trace of the necking results in a local annular recess DC2 towards the inside of the tube when it is directed towards the free end of the male element EM .

  In order not to hinder the progression of the ball in the tube T1, the shrinkage is preferably substantially continuous and the angle a7 is between about 2 and about 20, and more preferably about 5.

  When the first inner surface SI1 of the first lip L1 has an inclination (for example about 2.5), this allows the second lip L2 to be placed closer to the outside of the tube T2. Therefore, when the ball reaches the level of the second lip L2, it can be closer to the outside of the tube T2. In addition, this limits the effect called "banana" which tends to drop the second lip L2 to the inside of the tube cavity T2.

  This approximation can be accentuated by the presence of a local annular oversize SA2 in the direction of the inside of the tube T2, at the fifth internal surface SI5 of the second lip L2 and in the vicinity of the third abutment surface SB3. Preferably, as illustrated in FIGS. 4 to 7, this excess thickness SA 2 is substantially constant in the extension zone of the second lip L 2 and then decreases. This decay is preferentially substantially continuous. It thus initially constitutes a conical chamfer. It may for example be at an angle a8 relative to the longitudinal direction A, between about 8 and about 12, and more preferably equal to about 10.

  This oversize SA2 preferably depends on that of the first lip L1. It is more preferably still lower than that (SA1) of the first lip L1. In any case, it is less than a maximum value defined by the diameter of the buffer (or "drift"). For example, this extra thickness SA2 is between about 0.3 mm and 0.8 mm, and preferably equal to about 0.5 mm. The initial offset offered by different thicknesses SA1 and SA2 on the first L1 and second L2 lips can promote the final deformation, including the first lip L1. This offset must not be too important, however, since it could cancel the aforementioned effect offered by the inclination of the first internal surface SI1 of the first lip L1 (when it exists).

  As mentioned previously, the result of the ball-induced expansion is illustrated in FIG. 8. It is important to note that in the sleeved joints (and not in the integral joints), because the expansion causes With axial disengagement, the deformations of the first and second L2 lips may not be completely identical at the opposite ends of the sleeve. This difference (or dissymmetry) is however less than that occurring in the seals described in the document FR 02/03842.

  It is also important to note that the elastic return of the elements of the threaded joint after the passage of the ball is negligible in view of the plastic deformations involved.

  Referring now to Figure 9 to describe an exemplary embodiment of an assembly of two joints according to the invention, arranged symmetrically. In this example, the two joints make it possible to connect two tubes T1 and T2 of great lengths by means of a tubular element of type connection sleeve M. This sleeve M is here of symmetrical shape with respect to a plane of PSM symmetry perpendicular to the longitudinal axis A of tubes T1 and T2. It is also of the female / female type.

  Such a sleeve M comprises a central part PCM extended on both sides by two first parts P3 'and two second parts P4', of the same type as the first (P3) and second (P4) parts of the female end EF of the T2 tube presented above. Therefore, all that has been said about the first (P3) and second (P4) parts of the female end of the tube T2 also applies to the first portions P3 'and second portions P4' of the sleeve M.sub.0 ( As illustrated, the central PCM portion of the sleeve M preferably comprises an annular groove G2 (also called "lunula") locally defining a sub-thickness centered on the symmetry plane PSM.

  This lunette G2 makes it possible to reduce the thickness of the sleeve M in its thickest part and thus to reduce the pressures and the expansion forces. In addition, it allows better control deformations at different abutment surfaces (SB 1 to SB4) and worn while providing the joint a substantially straight (outer surface of revolution) after expansion. The thickness of the sleeve M at its plane of symmetry PSM must be chosen greater than or equal to the product of the section of the current portion of the tubes Ti and T2, at the ends of which are formed the first tubular elements, by the efficiency of the seal.

  Preferably, the lunula extends substantially between the two third axial abutment surfaces SB3 of the two opposite second lips L2. But, it can extend over a greater distance, especially between the last threads of the two female threads FF. The last threads are here those which are on the side of the third abutment surfaces SB3.

  Furthermore, this lunette G2 may be cup-shaped with a central portion having the maximum sub-thickness (at the plane of symmetry PSM) and sidewalls inclined at an angle preferably less than about 30, and more preferably equal to about 15.

  It is important to note that the lunula (and thus the groove G2) is not necessarily symmetrical with respect to the PSG plane. It can indeed have two asymmetrical parts on both sides of the PSG plane.

  Thanks to the invention, it is possible to obtain seals which have a good, or even excellent, tightness to gases under high pressure, both internal and external, before and after the expansion phase, including in the presence of high or very high expansion, typically between 10% and 35%. Of course, the invention also applies to expansion rates of less than 10%.

  In addition, the invention makes it possible not to "dissymmetrize" the deformations during expansion in the case of a sleeve assembly, and thus to provide a good seal threaded joints formed on each side of the central portion of the sleeve .

  Furthermore, the invention can be implemented in a large range of steels and alloys, provided that the material has sufficient ductility to expand. In the case of steels, the material may be unalloyed steel, or Mn steel, or Cr-Mo steel, or micro-alloy steel, or boron steel, or a combination of the above-mentioned compositions (stainless steel). Cr-Mo-Nb-B), or a 13% martensic Cr steel, or a 22% or 25% austenitic ferritic duplex steel, or austenitic stainless steel. For example, a C-Mn steel can be used for non-corrosive wells, or a 0.2% O steel and 13% Cr (X2OCr13 according to the name Euronorm and AISI 420 according to the US name), manufactured by the company VMOGF, for corrosive wells containing CO2.

  In addition, the material may optionally be heat-treated so as to have a yield strength greater than a chosen value or within a range of chosen values. The minimum elastic limit may for example be chosen in a range from 300 MPa to 1000 MPa or more.

  The invention is not limited to the methods and embodiments of sealed threaded tubular seals described above, only by way of example, but encompasses all the variants that can be envisaged by those skilled in the art within the scope of the invention. of the claims below.

Claims (28)

  An initial tubular seal comprising, on the one hand, a first tubular element (EM) having a first portion (P 1), provided with a male thread (FM), and a second portion (P2) extending said first portion and comprising a first annular lip (L1), having a first axial abutment surface (SB1), a first inner surface (SI1) and a first outer surface (SE1), and a second abutment surface (SB2), and another a second tubular element (EF) comprising i) a female thread (FF), homologous to the male thread (FM) and screwed onto it, ii) a second annular lip (L2), having a third abutment surface ( SB3) bearing against said second abutment surface (SB2), a second external surface (SE2), placed opposite said first internal surface (Sil), and a second internal surface (SI2), iii) a fourth abutment surface axial (SB4), and iv) a third inner surface (SI3) opposite to said female thread (FF) and defining with said second outer surface (SE2) and fourth abutment surface (SB4) an annular housing (LO) homologous to said first lip (L1), characterized in that said second (SB2) and third (SB3) abutment surfaces have respective convex and concave conical surfaces and angular inclinations with respect to a substantially identical longitudinal transverse plane (A) and selected to provide a bearing of said second abutment surface (SB2 against said third abutment surface (SB3) inducing tight radial tightness of said first inner surface (SI1) against said second outer surface (SE2), and such that, during a diametral expansion in the field of plastic deformation carried out subsequently on the initial tubular joint, said first external surface (SE 1) and said third internal surface (SI 3) are constrained to define locally a tight and tight contact.   2. Joint according to claim 1, characterized in that said inclinations are initially between about +5 and about +30.   3. Joint according to one of claims 1 and 2, characterized in that said first (L1) and second (L2) lips initially have selected shapes so that said first inner surface (SI1) and second outer surface (SE2) establishes a close contact only after pressing of said second abutment surface (SB2) on said third abutment surface (SB3).   4. Joint according to one of claims 1 to 3, characterized in that said first abutment surface (SB1) is arranged to be constrained during screwing to bear against said fourth abutment surface (SB4) so as to cause an axial compression of said first lip (LI) in the field of elastic deformations.   5. Joint according to one of claims 1 to 4, characterized in that the second outer surface (SE2) of said second lip (L2) initially has, at its connection with said third abutment surface (SB3), a annular portion inclined with respect to said longitudinal direction (A) of an angle of between about 8 and about 12, and preferably equal to about 10.   6. Joint according to one of claims 1 to 5, characterized in that said first inner surface (SI1) of the first lip (L1) is initially inclined relative to said longitudinal direction (A) by an angle of between approximately 0.1 and about 15.   7. Joint according to one of claims 1 to 6, characterized in that the ratio between the extension (PR) of the second lip (L2) in the longitudinal direction (A) and the extension (H) of the housing in the transverse direction is between about 1 and about 3, and preferably between about 1.2 and about 1.6.   2 0 8. Joint according to one of claims 1 to 7, characterized in that said male (FM) and female (FF) threads initially comprise threads provided with a load flank having a negative angle of between about - 3 and about - 15.   9. Joint according to one of claims 1 to 8, characterized in that said male (FM) and female (FF) threads initially comprise threads provided with an engagement flank having a positive angle of between about + 10 and about + 30.   10. Joint according to claim 9, characterized in that said male (FM) and female (FF) threads are arranged to present after screwing and before expansion an axial play between their sides of engagement between about 0.1 mm and about 0.3 mm.   11. Joint according to one of claims 1 to 10, characterized in that said first tubular element (EM) initially has at its first outer surface (SE 1) and before its first portion (P 1), a conical chamfer defining a local annular recess (DC 1) inwards.   12. Joint according to claim 11, characterized in that said chamfer has a substantially continuous slope with respect to the longitudinal direction (A) and between about 8 and about 12.   13. Joint according to one of claims 1 to 12, characterized in that said first tubular element (EM) is provided with a second portion (P2) initially having a local annular extra thickness selected (SA1) at a fourth level. inner surface (SI4) extending said second abutment surface (SB2) towards the first portion (P1), and a third inner surface (SE3) having at a chosen location a groove (G1) adapted to be placed after screwing substantially at said local excess thickness (SA1) and defining at the first outer surface (SE1) of the first lip (L1), during the diametrical expansion, an annular shoulder (EP) having at least a portion of the conformation of said groove (G1) and in tight and tight contact therewith.   14. Joint according to one of claims 1 to 13, characterized in that said first tubular element (EM) initially has at its first portion (P 1), on the opposite side to said male thread (FM), a conical narrowing in which is defined a local annular recess (DC2).   15. Seal according to claim 14, characterized in that said necking initially grows substantially continuously along a slope relative to the longitudinal direction A, between about 2 and about 20.   16. Seal according to one of claims 13 to 15, characterized in that it is initially provided a groove (G1) having at least two curvilinear portions (C1, C2).   17. Joint according to claim 16, characterized in that said curvilinear portions (C1, C2) initially have substantially identical radii of curvature.   18. Joint according to claim 17, characterized in that said radius of curvature is initially between about 2 mm and about 20 mm.   19. Seal according to one of claims 16 to 18, characterized in that the two curvilinear portions (C1, C2) are separated by a substantially cylindrical central portion (PC). oc   20. Joint according to one of claims 16 to 19, characterized in that said groove (G1) initially has a radial depth (H ') whose maximum value is chosen so that the material section at the bottom of the groove (G1) ) is greater than the product of the smallest section of a running part of the tubes (T1, T2) to which said first (EM) and second (EF) tubular elements belong by virtue of the efficiency of the tensile joint.   21. Seal according to one of claims 1 to 20, characterized in that said male (FM) and female (FF) threads are selected from a group comprising the conical type and cylindrical type threads, and are each formed on minus a tubular element portion (EM, EF).   22. Joint according to one of claims 1 to 21, characterized in that said first tubular element (EM) is provided with a first outer surface SEl convex.   23. Joint according to one of claims 1 to 22, characterized in that said second tubular member belongs to a connecting sleeve (M) substantially symmetrical female / female type and said first tubular element (EM) belongs to a terminal end. a tube of great length.   24. Joint according to claim 23, characterized in that said sleeve (M) comprises a central portion (PCM) extended on either side by two second tubular elements (EF1, EF2) and initially provided on an outer face of an annular zone (G2) having a sub-thickness chosen so that the initial thickness of said sleeve (M) at this zone (G2) is greater than or equal to the product of the section of a running portion of the tubes; (T1, T2), at the ends of which are formed said first tubular elements (EM), by the effectiveness of the seal.   25. A method of producing a sealed tubular joint, characterized in that it consists, from an initial tubular joint according to one of the preceding claims, - to screw said first (EM) and second (EF ) tubular elements until said first lip (L1) is housed in said annular housing (LO), and said second abutment surface (SB2) bears against said third abutment surface (SB3) so as to radially clamp , sealing, said first inner surface (SI1) against said second outer surface (SE2), and - to subject to said initial tubular joint, with the aid of an axial displacement expansion tool, a diametric expansion in the field of plastic deformation, so as to constrain said first outer surface (SE1) and said third inner surface (SI3) to locally define a tight and tight contact.   2863030 22 26. The method of claim 23, characterized in that one starts from first (L1) and second (L2) lips of shapes chosen so that said first inner surface (SI1) and second outer surface (SE2) establish a close contact only after pressing of said second abutment surface (SB2) on said third abutment surface (SB3).   27. Method according to one of claims 23 and 24, characterized in that said screwing first constrains said first abutment surface (SB 1) to abut against said fourth abutment surface (SB4) so as to cause an axial compression of said first lip (L1) in the field of elastic deformations.   28. Method according to one of claims 23 to 25, characterized in that the radial expansion of the seal is performed according to an expansion ratio of at least 10%. CABINET NET TER