EP3230551A1

EP3230551A1 - Tubular component with a helical abutment

Info

Publication number: EP3230551A1
Application number: EP15805508.7A
Authority: EP
Inventors: Fabien CARROIS; Didier David
Original assignee: Vallourec Oil and Gas France SAS
Current assignee: Tuboscope Vetco France SAS
Priority date: 2014-12-09
Filing date: 2015-12-08
Publication date: 2017-10-18
Also published as: CA2966957A1; AR103986A1; RU2017119835A; RU2017119835A3; CN107002472A; FR3029593B1; MX2017007528A; BR112017009990A2; WO2016091871A1; US20170370162A1; RU2722195C2; FR3029593A1; JP2017538901A

Abstract

The invention concerns a tubular drill stem component (1) comprising an end element (2; 3) having an axis of revolution (XX) and provided with a threading extending about the axis of revolution (XX), the end element (2; 3) being adapted to being connected by makeup onto a corresponding end element (103; 102) of another tubular component (101) provided with a complementary threading, the end element (2; 3) comprising at least one outer abutment (18) arranged so as to come into contact with a corresponding outer abutment (128) of the other component (101) at the end of makeup, and in which said outer abutment (18) comprises at least one helical surface (38; 148) having an axis of the helix which coincides with the axis of revolution (XX).

Description

TUBULAR COMPONENT WITH A HELICAL ABUTMENT

The present invention relates to a tubular component for connecting, by makeup, to an analogous component in order to form a contiguous pipework. Advantageously, the invention is of application in producing a stem formed by drill pipes, heavy weight drill pipes and drill collars, which are regularly fitted together and broken apart. A stem of this type may in particular be used when driven in rotation in order to drill hydrocarbon wells. Alternatively, tubular components of this type may also be used in a drill pipe riser or indeed a riser when operating a well of this type.

Each tubular component comprises at least one end element, male or female, which is threaded. In general, a tubular component comprises a male threaded end element and an opposed female threaded end element. The threaded end element is intended to be made up with the complementary threaded end element of another component. When connected, the two end elements of the two components form a connection.

The threaded tubular components are connected under carefully controlled loads which comply with requirements as regards tightening and sometimes as regards the seal, which depend on the conditions of use. In general, a threaded end element of a connection comprises at least one axial abutment which is activated at the end of makeup and clamped against a corresponding surface by application of a predetermined makeup torque. The makeup torque applied at the end of tightening is known as the torque on shoulder, as it corresponds to the torque necessary for activation of the axial abutments.

When two components are made up one with the other, the application of too low a torque on shoulder, for example as a result of a premature halt to makeup, produces a connection which does not comply with specifications. The risks of uncoupling by jump-out or accidental breakout are then high. Before uncoupling per se occurs, loss of tightness may also occur. Insufficient tightening favours rapid wear of the connections and difficulties when it comes to intentional breakout. The application of too high a torque on shoulder, for example as a result of over-torquing, also results in a connection which does not comply with specifications. Portions of the component are at risk of undergoing plastic deformation and damage as over-torquing commences. The intended cooperation between the various surfaces of each of the components is then no longer guaranteed. The behaviour of the junction becomes difficult to predict. Degradation of this type is difficult to repair.

In order to limit these risks, a nominal upper torque on shoulder at the shouldering torque and a lower torque on shoulder at the yielding torque are routinely determined. Adhering to the nominal torque on shoulder and its range of tolerances is a guarantee of satisfactory mechanical strength of the connection under the envisaged conditions of use. Adhering to this range limits the risks of malfunction. The limits to the range of the admissible torque on shoulder vary for each component configuration. The nominal values for such limits depend on the dimensions of the components, and in particular on the thicknesses of the walls which vary as a function of the envisaged applications.

In practice, makeup/breakout operations are carried out on-site under difficult conditions, for example on offshore platforms. Actual makeup conditions may be very different from the theoretical conditions in a laboratory.

In the applications envisaged by the present invention, a threaded end element of a connection may comprise two axial abutments which are axially separated, respectively inner and outer, which are activated at the end of makeup and clamped against corresponding surfaces by the application of a predetermined nominal makeup torque. The predetermined makeup torque for these connections is increased by doubling the surfaces which are engaged in abutment.

Wells to be drilled are becoming ever more complicated and ever longer, and the torque exerted on the upstream tubular components increases with increasing distance between the upstream tubular components and the downstream tubular components. The invention improves the situation by proposing tubular components which can be used to resist higher operational loads by proposing a higher nominal makeup torque than that of existing connections, without increasing either the outer dimensions of the connection nor the weight of the string. Further, another advantage of the invention is that it proposes an end element, in particular an abutment, the integrity of which is maintained throughout its use, and for which the seal against liquids is ensured even after several makeup-breakout operations.

For an identical wall thickness, a tubular component in accordance with the invention has at least one abutment the active surfaces of which are more extensive than those of known tubular components. The configuration of the invention means that the local contact pressures are not increased, thereby preventing plastification and guaranteeing that the abutments hold under tension traction and thus remain impervious even in service.

With the high makeup torque, the contact pressures on the abutment surfaces of the invention are subjected to loads per unit surface area which are identical to those of conventional annular surfaces or ring surfaces. The makeup torque beyond which plastification phenomena may occur is thus higher.

To this end, the invention provides a tubular drill stem component comprising an end element having an axis of revolution and provided with a threading extending about the axis of revolution, the end element being adapted to being connected by makeup onto a corresponding end element of another tubular component provided with a complementary threading, the end element comprising at least one outer abutment arranged so as to come into contact with a corresponding outer abutment of the other component at the end of makeup, in which said outer abutment comprises at least one helical surface having an axis of the helix which coincides with the axis of revolution.

In another aspect, the Applicant proposes a connection comprising two end elements of two distinct components as hereinbefore defined. The two components are connected to each other by making up the end element of the first component with the corresponding end element of the second component. The component may have the following optional characteristics, either alone or in combination with each other.

In particular, the threading has a thread angle such that the helical surface or surfaces may have a helix angle less than or equal to the thread angle of the threading. Advantageously, the helix angle may be in the range 0.5° to 7°.

In particular, a sum of the angular portions about the axis of revolution over which the helical surface extends may be in the range 180° to 360°.

As a consequence of the existence of the helical surface, the end element further comprises a circumferential shoulder connected to at least one of the circumferential ends of said helical surface.

In particular, this circumferential shoulder may comprise at least one substantially planar surface the plane of which forms an angle with the axis of revolution in the range 0° to 75°. In particular, the circumferential shoulder may comprise at least one substantially planar surface the plane of which may be parallel to the axis of revolution or may coincide with the axis of revolution.

In accordance with various embodiments, the circumferential shoulder may be connected to the helical surface via a fillet radius or an inclined plane. In particular, when a fillet radius is present, this may have a radius of curvature in the range 0.5 to 10.0 millimetres.

Advantageously, the end element may comprise two abutments, an inner abutment and an outer abutment, each of the two abutments comprising at least one circumferential shoulder.

Alternatively, the end element may comprise these two abutments, respectively the inner abutment and the outer abutment, such that only the outer abutment is provided with a helical surface.

In particular, the end element may comprise a single helical surface located solely on the outer abutment.

Advantageously, the helical surface may be at a distance from the threading; a distance between a threading end and the helical surface may in particular be at least 8 mm.

More particularly, the invention also concerns a connection comprising two components in accordance with the invention, in which one of the outer abutment of a component or the corresponding outer abutment of the other component is disposed at a free distal end of its end element.

Other characteristics, details and advantages of the invention will become apparent from the following detailed description and accompanying drawings in which:

- Figure 1 is a longitudinal partial sectional view of two components in accordance with the invention;

- Figure 2 is a perspective view of a male end element of a component in accordance with the invention;

- Figure 3 is a perspective view of a variation of a male end element of a component in accordance with the invention;

- Figure 4 is a perspective view of a female end element of a component in accordance with the invention, corresponding to that of Figure 3;

- Figures 5 to 8 are perspective views of variations of a detail of an end element of a component in accordance with the invention;

- Figures 9, 10 and 11 are perspective views of variations of a male end element of a component in accordance with the invention;

- Figure 12 is another variation of a male end element, provided with three helical surfaces in accordance with the invention.

The drawings and description below essentially contain elements of a specific nature. Thus, they may not only serve to act towards a better understanding of the present invention, but also contribute to its definition if necessary.

A first tubular component 1 and a second tubular component 101 are represented in Figure 1. The components 1 and 101 are generally in the form of a body of revolution about an axis of revolution XX. In Figure 1, the components 1 and 101 are aligned with each other. The axes of revolution XX therefore coincide. The direction of the axis of revolution XX is termed the axial direction. In order to facilitate comprehension, the numerical references for the second component 101 are greater by 100. Each of the components 1 and 101 comprises an end element 2 or respectively 103. Here, the first component 1 comprises a male end element 2 (or pin), while the second tubular component 101 comprises a female end element 103 (or box). The components 1 and 101 each comprise a regular tube portion 9 or 109. The regular portion 9 of the tube is integral with the male end element 2 and at an opposite end is also integral with a second female end element (not shown) which is identical to the female end element 103. Similarly, the regular tube portion 109 is integral with the female end element 103 and at an opposite end is also integral with another male end element (not shown) which is identical to the male end element 2.

The regular tube portions 9 and 109 of the two components 1 and 101 are similar to each other. The tubular components 1 and 101 are impermeable in structure and in material. In particular, the tubular components form metallic structures, in particular produced from steel or Inconel. As an example, the grade of the material is of the order of 130 ksi, with a yield strength in the range 120 000 to 140 000 psi; however, it may also be selected from higher grades of about 140 ksi, 150 ksi and 165 ksi, as well as from lower steel grades such as those defined at about 80 ksi or 95 ksi or even 110 ksi. The end elements 2 and 103 may be produced from a material which is identical to or different from that of the tubes 9 and 109.

Here, the end elements, in particular 2 and 103, have a configuration which conforms with the standard API-7 or API-RP-7G or indeed ISO- 10407- 1. In variations, the end elements 2 and 103 have a proprietary configuration, for example as marketed under the trademark VAM®

Express, or indeed as described in the publications WO-2006/092649 or WO-2012/089305.

The regular portion 9 is generally cylindrical in shape and has a length in the range 5 to 15 metres for long components, for example drill pipes, and 1 to 5 metres for short components, for example wear inserts used at the well head. The inner diameter is, for example, in the range 25 to 400 millimetres, while the external diameter is in the range 50 to 500 millimetres. The component 1 may be obtained by friction welding the end elements to each end of a tube forming the regular portion 9. The same mode of production may be employed for the component 101. In such cases, the ends of the regular portion 9 may have already been forged, upset or thickened so as to increase the radial surface of the metal. As can be seen in Figure 1, a weld plane 5 or 105 is respectively formed at the junction between the regular tube portions 9 and 109 with the end elements 2 and 103 respectively. Alternatively, the tubular component may be integral, namely without a weld, obtained from a single blank. The regular portions 9, 109 are not shown in Figures 2 to 8.

The end elements 2, 103 are generally tubular in shape. The end elements 2, 103 have an exterior surface 11, respectively 121, which is substantially cylindrical.

The end elements 2, 103 carry an interior surface 17, respectively 127, or bore, which is substantially cylindrical.

In general, the surfaces of revolution of the components 1 and 101 are substantially concentric with a centre belonging to the axis of revolution XX. The thicknesses of the walls of the components 1, 101 are substantially homogeneous in circumference, except at the positions of the end elements.

In use, the components 1 are manipulated using rams. The rams will hold the components 1 by means of their end elements 2 or 103. The end elements 2 and 103 are better suited to withstanding the loads applied, in particular during makeup/breakout operations. In particular, the exterior contact surfaces 11 or respectively 121 locally have a largest exterior diameter intended to be taken up in the jaws of working tongs in order to guarantee the final makeup torque of the connection to be formed. This exterior contact surface is that which will come into factional contact against the walls of the well during rotation of the drill stem.

Reference will now be made to Figures 1, 2 and 3 which represent three embodiments of a male end element 2 of a component 1. The male end element 2 comprises a substantially tapered exterior surface 12 in which at least one exterior threading known as the male threading is formed. The end element 2 further comprises an end surface 13 and a central surface 16. The exterior tapered surface 12 is located axially between the end surface 13 and the central surface 16. The end surface 13 and the central surface 16 are free of any threading. In the example shown, the end surface 13 and the central surface 16 have a substantially cylindrical profile.

In the example shown, the tapered exterior surface 12 with the threading comprises a threading having a single-start thread.

The end surface 13 connects to a surface 15 extending substantially in accordance with the thickness of the end element 2, substantially perpendicular to the end surface 13. This surface forms an inner abutment 15. The inner abutment 15 defines the free distal end of the end element 2 of the component 1 in the disconnected condition. This inner abutment 15 connects on the inside to an interior surface 17 which is substantially cylindrical. The inner abutment 15 is termed the male inner abutment.

The central surface 16 is connected to the exterior contact surface 11 via a surface which extends substantially along a portion of the thickness of the end element 2. This surface forms an outer abutment 18. The outer abutment 18 forms an exterior shoulder of the end element 2 of the component 1. The outer abutment 18 is termed the male outer abutment.

Advantageously, at least one of the inner abutment 15 and the outer abutment 18 has a helical surface. In the case in which the end element 2 has a single helical surface, this helical surface is produced on the outer abutment 18, as was the case with the helical surface 38 of Figure 2.

In Figure 2, the helical surface 38 is at a distance from the threading. An axial length Dl for the central surface 16 which is free of threading may be defined; in particular, this distance Dl is at least 8 mm and, for example, less than 24 mm. This distance Dl corresponds to the minimum axial distance along the axis XX between the helical surface 38 and the substantially tapered exterior surface 12 carrying the threading. The helical surface 38 is defined by an axis of the helix which coincides with the axis of revolution XX. The sense of the helix of the helical surface 38 corresponds to that of the threading of the tapered exterior surface 12. The helical surface 38 has a helix angle which has the reference a (alpha). The threading of the tapered exterior surface 12 has a thread angle with reference β (beta). The helix angle a of the helical surface 38 in this example is equal to the thread angle β of the threading.

By definition, the helical surface 38 is not flat. From another viewpoint, the helical surface 38 defines a surface the position of which varies along the axial direction as a function of the angular portion of the component 1, or angular sector, under consideration.

In Figure 2, the outer abutment 18 is connected to the exterior surface 11 via an annular chamfer 20.

In a variation, shown in Figure 3, the end element 2 is shown with two helical surfaces, such that the inner abutment 15 comprises a helical surface 35 and the outer abutment 18 comprises the helical surface 38.

In Figure 3, the helical surface 35 is also at a distance from the threading. An axial length

D2 of the end surface 13 which is free of threading may be defined, this distance D2 in particular being at least 8 mm, for example less than 24 mm. This distance D2 corresponds to the minimum axial distance, along the axis XX, between the helical surface 35 and the substantially tapered exterior surface 12 carrying the threading. This distance D2 also corresponds to the axial distance between the free distal end of the end element 2 and the threaded exterior surface 12.

In the embodiments of Figures 2 and 3, each angular portion of the helical surface 38 extends in a radial direction, i.e. perpendicular to the axis of revolution XX. In other words, the profile of the helical surface 38, viewed in a longitudinal section passing through the axis of revolution XX, may be represented by a straight segment orientated in a radial direction. The width of the helical surface 38 is thus substantially equal to the radial distance of the outer abutment 18. Analogous reasoning applies to the helical surface with respect to the inner abutment 15. In variations (not shown), the profile of the helical surface 38 may be straight and have a non-zero inclination with respect to a radial direction. In this case, the helical surface 38 has a generally tapered configuration. The width of the helical surface 38 is thus substantially greater than the radial thickness of the outer abutment 18. In other variations, the profile of the helical surface 38 may be curved, for example concave or convex. The radial width of the helical surface 38 is thus substantially greater than the outer abutment 18.

In the embodiments of Figures 2 and 3, the helical surfaces 35 and 38 extend over the whole circumference of their respective abutments, i.e. approximately 360°. The helix angle a of the helical surfaces 35 and 38 are substantially identical. In this example, the helix angle a is substantially equal to the thread angle β of the threading of the tapered exterior surface 12. The helix angle a of the helical surface 38 is in the range 0.5° to 7°, for example.

The presence of the helical surfaces 35 and 38 results in the formation of a circumferential shoulder 36 or respectively 39 on each of the abutments 15 and 18. The two circumferential shoulders may be substantially planar, each forming a plane comprising the axis XX. They may be designed so as to be in the same plane.

The outer abutment 18 of the end element 2 thus comprises the circumferential shoulder 39. The circumferential shoulder 39 extends over an axial position of the end element 2 which is identical to that over which the helical surface 38 extends. When the helical surface 38 is 360°, the circumferential shoulder 39 connects the two circumferential ends of the helical surface 38 one to another.

Figure 5 shows a detail of the circumferential shoulder 36 of the embodiment of Figure 3. The two circumferential ends of the helical surface 35 are aligned in the axial direction, and so here, the circumferential shoulder 36 exhibits a zero circumferential component. In the example of Figures 2 and 3, the circumferential ends of the helical surface 38 are aligned in the axial direction, with the circumferential shoulder 39 here having a zero circumferential component. In these configurations, the circumferential shoulder 39 defines a plane passing through the axis XX. In particular in Figure 3, the circumferential shoulders 36 and 39 are defined in the same plane.

In Figure 6, the circumferential shoulder 36 comprises a substantially planar surface. The plane of the planar surface forms an angle γ (gamma) with the axis of revolution XX. In the embodiments of Figures 2 and 3, the plane of the respective planar surface of the circumferential shoulders 36 and 39 here is substantially coincident with the axis of revolution XX. The angle γ is thus substantially zero. The planar surface of the circumferential shoulders 36 and 39 extends substantially perpendicular to the helical surfaces 35 and 38, plus or minus the helix angle a.

In the example of Figure 2, the circumferential shoulder 39 is connected to both of the circumferential ends of the helical surface 38 via sharp borders or edges. This is also the case in Figure 3 for the circumferential shoulders 36 and 39.

Figures 6, 7 and 8 show variations of the helical surfaces. To make these variations more legible, they are shown on the inner abutment 15. Clearly, each of the variations may also be applied to the embodiment in which the helical surface is on the outer abutment 18 as shown in Figures 9, 10 and 11. These variations are primarily distinguished from the embodiment of Figure 3 in that the helical surface 35 extends over an angular portion of less than 360°. The two

circumferential ends of the helical surface 35 are out of alignment in the axial direction. The circumferential shoulder 36 linking them has a non-zero circumferential component. The circumferential shoulder 36 extends over an angular portion of several degrees, for example between 1° and 15°.

In the variations of 6, 7 and 8, the profile of the surfaces of the circumferential shoulder 36, viewed in a longitudinal section passing through the axis of revolution XX, may be represented by straight segments orientated in a radial direction. As was the case for the helical surface 35, in a variation the profile of the circumferential shoulder 36 is straight and has an inclination with respect to a radial direction. In other variations, the profile of the surfaces of the circumferential shoulder 36 may be curved, for example concave or convex. In the variation of Figure 6, the circumferential shoulder 36 comprises a substantially planar surface. The plane of the planar surface forms an angle γ with the axis of revolution XX. Here, the angle γ is non-zero, for example in the range 0° to 75°. As was the case with Figure 2, the circumferential shoulder 36 is connected to both of the circumferential ends of the helical surface 35 via sharp borders or edges.

In the variation of Figure 7, the circumferential shoulder 36 comprises two fillet radii, one being concave and the other, convex. The fillet radii each have a radius of curvature, respectively with references Rl and R2. The connections between the circumferential shoulder 36 and the helical surface 35 do not have a sharp border or edge. In a variation, not shown, the circumferential shoulder 36 might not have a planar surface, so that the fillet radii are connected to each other via a point of inflexion in a manner such that the circumferential shoulder 36 forms a substantially continuous link between the two circumferential ends of the helical surface 35. Here, the radii of curvature Rl and R2 are substantially equal. The radii of curvature Rl and R2 are in the range 0.5 to 10 millimetres, for example.

In the variation of Figure 8, the circumferential shoulder 36 comprises two substantially planar, mutually intersecting surfaces. A first plane 36' forms a zero angle γ with the axis of revolution XX. In contrast to the case of Figure 3, the planar surface is connected to one of the two circumferential ends of the helical surface 35 via a second plane 36" in the form of a chamfer, here at substantially 45°. Here, the chamfer is provided on the side of the concave connection with the helical surface 35. Instead of or in addition, a chamfer may be provided on the side of the convex connection with the helical surface 35.

In other variations, the helical surface 35 extends over a little more than 360°, i.e. one turn plus a few degrees, for example between 361° and 365°. The circumferential end portions of the helical surface 35 are then slightly superimposed in the axial direction at a singular angular portion of the component 1. The circumferential shoulder 36 is then shaped into a concavity connecting the two circumferential ends of the helical surface 35 with each other. In a variation of Figures 9, 10 and 11 (not shown), the inner abutment 15 might not have a helical surface, while the inner abutment is provided with a single helical surface in one of the variations.

In other embodiments, the abutment 15 comprises a helical surface 35 which extends over an angular portion which is significantly less than 360°, for example less than 270°, or more preferably less than 180° or less than 90°.

In the cases in which the helical surface extends over an angular portion of significantly less than 360°, the abutment then comprises said single helical surface, a single circumferential shoulder and the remaining angular portion of the abutment which then defines a surface in the form of a portion of a ring. The profile of the surface in the form of a portion of a ring, viewed in longitudinal section, may be planar and parallel to a radial direction, planar and inclined with respect to a radial direction or indeed curved, for example convex or concave. The abutment 18 comprises the surface in the form of a portion of a ring, the helical surface 38 and the circumferential shoulder 39, in succession along the circumference. In this case, the circumferential shoulder 39 connects a circumferential end of the helical surface 38 to a circumferential end of the surface in the form of a portion of a ring.

In a variation, Figure 12, the abutment 18 comprises at least two helical surfaces 38. The abutment 18, as a consequence, comprises as many circumferential shoulders 39 as there are helical surfaces 38. The abutment 18 comprises, in succession along the circumference, a first helical surface 38', a first circumferential shoulder 39', a second helical surface 38", and a second circumferential shoulder 39". In the example of Figure 12, the inner abutment 15 also has a helical surface 35, and so it constitutes an embodiment with three helical surfaces.

In accordance with the invention, the presence of N helical surfaces may be combined with N planar surfaces in the form of a portion of a ring. The abutment then comprises a succession of N ensembles along the circumference, constituted by a helical surface, a surface in the form of a ring and a circumferential shoulder. The sum of the angular portions over which the N helical surfaces extend is, for example, in the range 180° to 360°.

Each characteristic, embodiment, variation and combination which derives from the description above in respect of the abutment 15 can be transposed to the abutment 18 and vice versa. Furthermore, the first end element 2 of a component 1 may comprise:

i) an abutment 15 in accordance with one of the embodiments described above on the inside and an abutment with configuration which is known per se on the outside;

ii) an abutment 18 in accordance with one of the embodiments described above on the outside and an abutment with configuration which is known per se on the inside;

iii) a combination of an abutment 15 in accordance with one of the embodiments described above on the inside and an abutment 18 on the outside, the abutments 15 and 18 being analogous; or

iv) a combination of an abutment 15 in accordance with one of the embodiments described above on the inside and an abutment 18 in accordance with one of the embodiments described above on the outside, the abutments 15 and 18 having different configurations.

The circumferential shoulders 36 or respectively 39 may be disposed in the same angular portion of the component 1 , as seen in Figure 3, or be offset with respect to each other.

Reference will now be made to Figures 1 and 4, representing two embodiments of a female end element 103 of a component 101. The female end element 103 of Figure 4 corresponds to and matches the shape of the male end element 2 of the component 1 of Figure 3. Because the shapes match, at the very least it is to be expected that the inner abutment 15 and outer abutment 18 can be placed in sealing engagement over 360° with the corresponding surface carried by the female end element 103, and that the threaded portions can be engaged together.

The female end element 103 comprises a substantially tapered interior surface 122 in which an interior threading is provided. The end element 103 further comprises an end or distal surface 126 and a central or proximal surface 123. The threading of the interior tapered surface 122 is located axially between the end surface 126 and the central surface 123. The end surface 126 and the central surface 123 are free of a threading. The end surface 126 and the central surface 123 are substantially cylindrical and match the shape of the central surfaces 16 and the end surfaces 13 of the male end element 2. A space is provided between these respective cylindrical portions in order to form a backflow zone for grease deposited on the threads; this grease might have been deposited in a quantity which is larger than the residual interstitial space provided between the threads at the end of makeup.

The end surface 126 has a diameter which is larger than that of the central surface 123. The threading of the interior tapered surface 122 is located radially between the end surface 126 and the central surface 123.

During connection, the axis of makeup corresponds to the axis of revolution XX. The sense of makeup is imposed by the sense of the complementary threadings of the exterior 12 and interior 122 tapered surfaces. The embodiment of Figures 3 and 4 comprises threadings with a conventional makeup sense, i.e. the end elements 2, 103 have right handed threads.

The central surface 123 and the interior surface 127, both substantially cylindrical, are connected to each other via a surface extending substantially along a portion of the thickness of the end element 103. This surface forms an abutment 125. The inner abutment 125 forms an interior shoulder of the end element 103 of the component 101.

The end surface 126 and the exterior surface 121, both substantially cylindrical and concentric, are connected one to the other via a surface extending substantially along the thickness of the end element 103. This surface forms an outer abutment 128. The outer abutment 128 defines the free distal end or terminal end of the end element 103 of the component 101 in the uncoupled state.

Because of their respective radial positions, the inner abutment 125 may be termed the female inner abutment, while the outer abutment 128 may be termed the female outer abutment. The inner abutment 125 of the end element 103 of the component 101 corresponds to the inner abutment 15 of the end element 2 of the component 1. The shape of the abutment 125 matches that of the abutment 15. The abutment 15 and the abutment 125 are arranged so as to come into clamping contact one against the other at the end of makeup, and so as to obtain, at all points of the inner abutment 15 facing the abutment 125, a sufficient contact pressure to ensure a seal against fluids, at least to liquids.

The outer abutment 128 of the end element 103 of the component 101 corresponds to the outer abutment 18 of the end element 2 of the component 1. The shape of the abutment 128 matches that of the abutment 18. The abutment 18 and the abutment 128 are arranged so as to come into clamping contact one against the other at the end of makeup, and so as to obtain, at all points of the outer abutment 18 facing the abutment 128, a sufficient contact pressure to ensure a seal against fluids, at least to liquids.

In a connection obtained when the two components 1 and 101 are connected one with the other by makeup, the end element 2 of the first component 1 corresponds to the end element 103 of the second component 101. The N helical surfaces 35, respectively 38, are homologues of the N helical surfaces with references 145, 148 respectively and the N circumferential shoulders 36 or respectively 39 are homologues of the N circumferential shoulders 146, respectively 149 provided on the end element 103.

In Figure 4, the helical surface 148 is distant from the threading. The end surface 126 which is free of a threading covers an axial distance D3 along the axis XX, distance D3 being not necessarily equal to the axial distance Dl. This axial distance D3 also corresponds to the distance between the free distal end of the end element 103 and the threaded interior tapered surface 122. is This non-zero axial distance D3 is at least 8 mm and, for example, less than 24 mm.

The threadings of the exterior 12 and interior 122 tapered surfaces are complementary. Here, the threadings of the exterior 12 and interior 122 tapered surfaces have a single thread. In a variation, the threadings comprise several threads, for example two, three or four. These are known as multi-start threadings. The threadings have a constant pitch.

The operation for connecting the two components 1 and 101 will now be described. In the example of Figure 1 or Figures 3 and 4, the male end element 2 of the first component 1 is connected together with the female end element 103 of the second component 101 . This is equivalent to connecting the male end element (like 2) of the second component 101 with the female end element (like 103) of the first component 1. Each of the surfaces of the first component 1 mentioned above can then cooperate with a corresponding surface of the second component 101 . During an uncoupling operation, i.e. breakout, the following events and their order are reversed.

Before connection, the components 1 and 101 are aligned one with the other such that their axes of revolution XX coincide and the male element 2 of the first component 1 is disposed facing the female end element 103 of the second component 101.

At the start of connection:

- the male end element 2 is partially inserted into the female end element 103 by means of a translational movement along the axis of revolution XX to bring the components 1 , 101 towards each other;

- using a screwing movement, the threading of the exterior tapered surface 12 and the threading of the interior tapered surface 122 come into engagement with each other.

- At the end of screwing up:

- the exterior surfaces 1 1 and 121 are substantially in the extension of each other in the axial direction and are drawing closer to each other;

- the interior surfaces 17 and 127 are substantially in the extension of each other in the axial direction and are drawing closer to each other;

- the abutment 15 comes into contact against the abutment 125. In other words, the inner abutments 15 and 125 come into contact with each other; - the abutment 18 comes into contact against the abutment 128. In other words, the outer abutments 18 and 128 come into contact with each other;

- the N helical surfaces 35 come into contact against the N helical surfaces 145. In other words, the helical surfaces 35 and 145 come into contact in pairs;

- the N helical surfaces 38 come into contact against the N helical surfaces 148. In other words, the helical surfaces 38 and 148 come into contact in pairs;

- the N circumferential shoulders 36 approach each other facing the N circumferential shoulders 146. In other words, the circumferential shoulders 36 and 146 approach each other in pairs;

- the N circumferential shoulders 39 approach each other facing the N circumferential shoulders 149. In other words, the circumferential shoulders 39 and 149 approach each other in pairs.

At the end of tightening:

- the exterior surfaces 11 and 121 form a quasi-continuous exterior surface passing from one component 1, 101 to the other;

- the interior surfaces 17 and 127 form a quasi- continuous exterior bore passing from one component 1, 101 to the other;

- the abutment 15 is in clamping contact against the abutment 125, which means that a large makeup torque can be applied;

- the abutment 18 is in clamping contact against the abutment 128, which means that a large makeup torque can be applied;

- the circumferential shoulders 36 and 146 are in contact or almost in contact;

- the circumferential shoulders 39 and 149 are in contact or almost in contact.

The abutments in accordance with the invention comprising at least one helical surface have a larger active surface than abutments constituted by a surface in the form of a planar ring perpendicular to the axis of revolution XX as is known in the prior art. Shaping helical surfaces, for example by machining, into the planar surfaces of a tubular component means that the load transmission surface can be increased. The radial dimensions of the end element, such

internal and external diameters and the thickness of the tubular wall, remain unchanged. The risks of malfunction in use and the difficulties during breakout operations are reduced.

As an example, for an embodiment in accordance with Figure 3 with helical surfaces respectively formed on the outer abutment and the inner abutment, the following results are obtained for a connection with a single-start thread in the threaded zone:

and the following results with the same configuration with two helical surfaces, but in this case provided with a double-start thread in the threaded zone:

The higher the pitch of the thread, the larger may be the helix angle, and as a consequence the beneficial effect on the improvement of the nominal makeup torque may be obtained. It will be noted that advantageously, the gain in terms of the final makeup torque is larger when the thread is multi-start. Because the thread pitch is greater when there are more thread starts, increasing the thread angle means that an increase in the helix angle can be obtained.

It will also be noted that another significant advantage can be obtained on the improvement in gains on the small diameters of tubular components, often disposed at the very bottom of the well at a long distance from the head of the drilled well and on which it is hardest to generate high makeup torques.

The distance separating the circumferential shoulders 39 and 149 on the outside is visible from the outside of the connection. This can therefore constitute a visual indicator to operators monitoring the quality of makeup.

When the circumferential shoulders 39 and 149 and if appropriate 36 and 146 come into contact, the reactional force opposing makeup increases abruptly. The circumferential shoulders 36 and 146 or respectively 39 and 149 then form circumferential abutments to stop makeup. The torque necessary to continue makeup increases abruptly. This abrupt increase is readily detectable by makeup tools equipped with dynamometric sensors. Makeup can be stopped before over- torquing occurs. Stopping makeup when an abrupt increase in the torque is detected may be automated. The risks o damaging the end elements such as 2 and 103 of the components 1, 101 of the connection are reduced.

The invention is not limited to the examples of components and connections described above, given solely by way of example, but it encompasses any and all variations that the skilled person may envisage in the context of the claims below.

Claims

1. A tubular drill stem component (1) comprising an end element (2; 3) having an axis of revolution (XX) and provided with a threading extending about the axis of revolution (XX), the end element (2; 3) being adapted to being connected by makeup onto a corresponding end element (103; 102) of another tubular component (101) provided with a complementary threading,

the end element (2; 3) comprising at least one outer abutment (18) arranged so as to come into contact with a corresponding outer abutment (128) of the other component (101) at the end of makeup,

characterized in that said outer abutment (18) comprises at least one helical surface (38;

148) having an axis of the helix which coincides with the axis of revolution (XX).

2. The component (1) according to the preceding claim, in which the threading has a thread angle (β) such that the helical surface (38; 148) has a helix angle (a) less than or equal to the thread angle (β) of the threading.

3. The component (1) according to one of the preceding claims, in which the heli angle (a) is in the range 0.5° to 7°.

4. The component (1) according to one of the preceding claims, in which the sum of the

angular portions about the axis of revolution (XX) over which the helical surface (38; 148) extends is in the range 180° to 360°.

5. The component (1) according to one of the preceding claims, in which the end element (2;

3) further comprises a circumferential shoulder (39; 149) connected to at least one of the circumferential ends of said helical surface (38; 148).

6. The component (1) according to claim 5, in which the circumferential shoulder (39; 149) comprises at least one substantially planar surface the plane of which forms an angle (γ) with the axis of revolution (XX) in the range 0° to 75°.

7. The component (1) according to one of claims 5 and 6, in which the circumferential shoulder (39; 149) comprises at least one substantially planar surface the plane of which is parallel to the axis of revolution (XX) or coincides with the axis of revolution (XX).

8. The component (1) according to one of claim.s 5 to 7, in which the circumferential shoulder (39; 149) is connected to the helical surface (38; 148) via a fillet radius or an inclined plane.

9. The component (1) according to claim 8, in which the fillet radius has a radius of curvature (Rl ; R2) in the range 0.5 to 10.0 millimetres.

10. The component (1) according to one of the preceding claim.s. in which the end element (2;

3) comprises two abutments (15, 18), an inner abutment and an outer abutment, each of the two abutments (15, 18) comprising at least one circumferential shoulder (36, 39; 146, 149).

11. The component (1) according to one of claims 1 to 9, in which the end element (2; 3)

comprises two abutments ( 15, 18), an inner abutment and the outer abutment, only the outer abutment (18) being provided with a helical surface.

12. The component (1) according to one of the preceding claim.s, in which the helical surface (35; 38; 145; 148) is at a distance from the threading, a distance (Dl; D2; D3) between a threading end and the helical surface in particular being at least 8 mm.

13. A connection comprising two components (1, 101) according to one of the preceding

claims, in which one of either the outer abutment (18) of a component (1) or the

corresponding outer abutment of the other component (101) is disposed at a free distal end of its end element (2; 3).

14. The connection comprising two end elements (2, 103; 3, 102) of two components (1, 101) according to one of the preceding claims, the two components (1 , 101) being connected together by makeup of the end element (2, 3) of the first component (1) with the corresponding end element (103, 102) of the second component (101).