Tubular threaded connections for the drilling and / or development of hydrocarbon wells

Abstract

A tubular threaded connection for hydrocarbon well casing is obtained by threading a male tool interface and a female tool interface, the connection comprising, in order from a free edge (19) of the male tool interface, a metal-to-metal inner seal (25, 26), a first threaded portion (16a, 18a), an intermediate abutment portion (22, 24), a metal-to-metal intermediate seal (27, 28), and a second threaded portion (16b, 18b). The free edge (19) is a non-zero axial distance (d) from the female tool interface. Each of the threaded portions comprises a helix having a load flank, a crest, a stab flank, and a root. The load flank pitch (LFLp1, LFLb1) and stab flank pitch (SFLp1, SFLb1) of the first thread portion, and the corresponding load flank pitch (LFLp2, LFLb2) and stab flank pitch (SFLp2, SFLb2) of the second thread portion are determined by the following formula: [Equation 1] It is designed to meet the requirements of JPEG2022541053000013.jpg8120.

Description

[Technical field]

[0001] The present invention relates to a connection or assembly of pipes intended to be connected by threads, for pipes used in the relevant industries, more particularly to a threaded assembly or coupling intended to comprise a tubing string or a production tubing accessory or casing string for prospecting, exploration or development of oil or gas wells, and also to a threaded assembly or coupling used in any application requiring the assembly of pipelines or tubing accessories, for example in the geothermal energy industry or in steam production. The threaded assembly according to the invention is particularly useful for the assembly of metal pipes used for casing oil or gas wells, as will be described below. [Background technology]

[0002] In this specification, the terms "assembly", "connection", "joining" or "joining" are used interchangeably except in certain contexts. By "pipe" is meant any type of pipe, tubular element or tubing accessory present in the industry or suitable for use in the industry. These pipes are generally metal pipes. In particular, these pipes are seamless pipes obtained from steel as defined in API specification 5CT or steel conforming to ISO standard 11960:2004. Preferably, the connections according to the invention are obtained between pipes made from materials with high capacity breaking strength, for example steel grades ranging from 862 MPa to 965 MPa (125 ksi to 140 ksi).

[0003] Numerous types of assemblies for oil or gas pipes are known that give satisfactory results in terms of mechanical properties and tightness even in harsh operating environments. In some of these assemblies, a pipe with a frusto-conical external thread is assembled at its two ends by a coupling with two corresponding frusto-conical internal threads. This assembly method has the advantage that the two components of the assembly are rigid due to the positive interference that can occur between the external and internal threads. This is a threaded joint connection method, also called T&C connection.

[0004] However, the outer diameter of these couplings is larger than the outer diameter of the corresponding pipes, so that when such an assembly is used with casing pipes, it is necessary to make a borehole with an increased diameter. For very deep wells, such as those with a depth of more than 4000 m, it is necessary to lower the casing deeper into the well, for which it is known that an assembly without couplings is preferable, as described in US Pat. No. 2992019, EP Pat. No. 0767335 or US Patent Application No. 2013 / 0015657. In this case, each of the tubes includes a first end with a male tool interface and a second end with a female tool interface. The tubes are assembled end to end by connections between the male and female tool interfaces. Such an assembly is shown as "one piece".

[0005] In order to meet the increasing requirements for resistance to internal and external pressures, a one-piece connection with two threaded portions arranged in a staggered manner on both sides of the intermediate abutment is known from US Pat. No. 4,662,659. Here, the intermediate abutment is designed with a negative angle in order to increase the resistance to pressures. This document also describes that on one side of the intermediate abutment or on both sides of the intermediate abutment, a sealing area is provided by radial interference between conical surfaces, the taper angles of which vary slightly relative to each other by an angle γ. According to this document, the seal is only provided in the middle between the two threaded portions, close to the intermediate abutment. US Patent Application No. 20190040978 proposes an alternative to US Pat. No. 4,662,659. Here, a specific shape of these seals on both sides of the intermediate abutment is specified, the shape of the thread is varied, and a thread with a dovetail profile is selected.

[0006] Another connection is also known from US patent application 20170101830, which has two threaded sections arranged in a staggered manner on either side of an intermediate abutment. According to this document, a seal is provided between the threaded section and this intermediate abutment. Since the definition of the seal reduces the performance and capacity of the intermediate abutment, this document describes the provision of an additional abutment surface at the level of the distal end of the male tool joint. Alternatively, other documents propose to vary the thread to compensate for the reduced performance of the intermediate abutment during compression. Such alternative threads are called "dovetail" threads and are screwed in to obtain a locking connection of the threaded sections. For this purpose, a threaded section is proposed with different pitch values ​​for the load flank and the stub flank. The helical section of this thread thus has a tooth width that gradually increases with the turns of the helical section from one end to the other, and the recess defined between the tips of the helical sections decreases along the same direction. In this way, the threaded section is screwed in until contact is obtained between the stub flanks and also between the load flanks. This type of connection, also known as a "self-locking wedge screw," is very effective but is very difficult to machine and use in assembly. Summary of the Invention [Problem to be solved by the invention]

[0007] In spite of the various solutions already known, there is still a need to facilitate the machining of one-piece connections suitable for forming casings for very deep wells, achieving performance in terms of resistance to cycles of internal and external pressure, tolerances under towing and compression, while allowing for the machining and assembly tolerances inherent in the field of oil and gas pipes. In fact, it has been found that the method of applying the assembly grease to the joint is a key factor for the success of the connection. The threaded connection according to the invention allows better tolerance of handling variations at the moment of applying a certain amount of grease.

[0008] The advantage of the present invention is that it provides an integral connection that meets the technical requirements close to those of sleeved couplings and allows for an effectiveness close to that of the tube. In particular, the connection according to the invention can have an effectiveness equal to 96% of the effectiveness of the tube. Effectiveness is generally defined as the relationship between the critical portion of the connection and the cross-section of a regular portion of the tube between the two ends of the components. The critical portion of the connection is the minimum of the male tool interface or the female tool interface. Critical part is equal to.

[0009] Preferably, the invention applies to threaded connections having large diameters, especially pipes having an outside diameter greater than 7 inches, preferably greater than 10 inches, for example greater than 16 inches. [Means for solving the problem]

[0010] The present invention relates to these points and provides connections with better adhesion.

[0011] The subject of the present invention relates to a tubular threaded connection for drilling and / or developing hydrocarbon wells. The connection comprises a first tube having a male tool interface at a first distal end and a second tube having a female tool interface at a second distal end. The male tool interface is assemblable by threading into the female tool interface. The first tube is assembled to the second tube to define a longitudinal axis X together with the second tube. The male tool interface comprises, in order from the free edge of the first distal end towards the body of the first tube, a male inner sealing surface, a first male threaded portion, a male abutment shoulder, a male intermediate sealing surface and a second male threaded portion. The female tool interface comprises a female inner seal surface intended to form an inner seal with the first male seal surface by radial interference when the connection is assembled, a first female threaded portion engaging the first male threaded portion, a female abutment shoulder abutting the male abutment shoulder, a female mid-seal surface intended to form a mid-seal with the male mid-seal surface by radial interference, and a second female threaded portion engaging the second male threaded portion. The free edge of the first distal end is at a non-zero axial distance (d) from the female tool interface in the assembled position. Each of the male threaded portions comprises at least one helix having a load flank, a crest, a stab flank, and a root. The load flank pitch LFLp1 and the stub flank pitch SFLp1 of the first male thread portion and the corresponding load flank pitch LFLp2 and the stub flank pitch SFLp2 of the second male thread portion are set to satisfy the following condition:

number

[0012] Preferably, each of the female thread portions may include at least one helical portion having a load flank, a crest, a stab flank, and a thread root. The load flank pitch LFLb1 and the stub flank pitch SFLb1 of the first male thread portion and the corresponding load flank pitch LFLb2 and the stub flank pitch SFLb2 of the second male thread portion may be determined by the following formula:

number

[0013] Preferably, the constants k1 and k2 may be equal to each other.

[0014] For example, the first female threaded portion may have an annular groove, which may have a radial width less than the constant k2, and which is radially spaced apart from at least two complete turns of the helical portion of the first female threaded portion.

[0015] Preferably, the helical portion of the first female threaded portion may be frustoconical, for example with a taper in the range of 5% to 15%, preferably in the range of 8% to 12%, in which case the helical portion of the first male threaded portion may comprise a frustoconical portion having the same taper as the taper of the helical portion of the first female threaded portion, and a cylindrical portion adjacent to the inner sealing surface.

[0016] Advantageously, the helical section of the second female threaded section may be frustoconical, preferably specifically frustoconical, for example with a taper in the range 5% to 15%, preferably 8% to 12%, in which case the helical section of the second male threaded section may comprise a frustoconical section with the same taper as the taper of the helical section of the second female threaded section, and a cylindrical section adjacent to the intermediate sealing surface.

[0017] Preferably, the inner seal may be a ring-to-cone type seal, for example the male inner seal surface is tapered and the female inner seal surface comprises a ring portion. Advantageously, the mid-seal may be a seal of a different type to the inner seal. The mid-seal may be a cone-to-cone type seal. In this case, the male mid-seal surface and the female mid-seal surface are tapered, in particular having substantially the same taper.

[0018] More specifically, the female inner seal surface can include, from the body of the second tube to the second distal end, a first arcuate portion having a radius R1 and a second arcuate portion having a radius R2, the radii being determined by the following condition:

number

[0019] The stub flank and the load flank of the helical portion of the male thread portion can include straight portions that are connected to the adjacent crest and root portions, respectively, via transition portions, such that the stub flank of the female thread portion can include at least one straight portion parallel to the stub flank of the male thread portion for the first thread portion and the second thread portion.

[0020] The invention also provides advantages if the second distal end of the second tube can be upset, i.e. pushed back to obtain additional thickness. Advantageously, the two distal ends of this second tube are upset.

[0021] Alternatively, and / or in combination, the second distal end of the second tube can have an outer diameter that is less than 103% of the outer diameter of the second tube, in which case the connection is said to be "partially flush."

[0022] In a preferred embodiment of the invention, each of the male threaded portion and the corresponding female threaded portion can have a single helix. In this case, the helix of the male threaded portion and the helix of the corresponding female threaded portion can have at least three turns, preferably at least four turns. However, in a variant, the first male threaded portion and / or the second male threaded portion can have multiple helixes. These helixes extend along the same portion of the longitudinal axis. The starting points of these helixes are such that they can be evenly distributed, for example, in a plane perpendicular to the longitudinal axis of the connection. The pitch of each helix is ​​therefore greater than in the case of a single helix configuration.

[0023] For ease of assembly, the crests and roots of the male and female threaded portions may have a taper that is less than the taper of the threaded portions, e.g., parallel to the longitudinal axis of the connection, in which case the radial height of the stub flank of the male threaded portion may be greater than the radial height of the load flank of that male threaded portion. [Brief description of the drawings]

[0024] Other features and advantages of the present invention will become apparent from the following detailed description which refers to the accompanying drawings. [Figure 1] FIG. 2 is an external profile view of a first tube according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of a second tube according to the present invention. [Diagram 3] FIG. 2 is a partial cross-sectional view of the male tool interface of the first tube shown in FIG. 1. [Figure 4] FIG. 3 is a partial cross-sectional view of the female tool interface of the second tube shown in FIG. 2. [Diagram 5] FIG. 3 is a partial cross-sectional view showing the assembly of the male tool interface of the first tube shown in FIG. 1 to the female tool interface of the second tube shown in FIG. 2, and also showing the stress levels achieved within the connection after assembly. [Figure 6]FIG. 13 is a partial cross-sectional view of the unthreaded female intermediate portion of a female tool interface according to the present invention. [Figure 7] FIG. 13 is a partial cross-sectional view of the unthreaded male intermediate portion of a male tool interface according to the present invention. [Figure 8] FIG. 13 is a partial cross-sectional view of the unthreaded female inner portion of a female tool interface according to the present invention. [Figure 9] FIG. 13 is a partial cross-sectional view of the unthreaded male inner portion of a male tool interface according to the present invention. [Figure 10] FIG. 13 is a partial cross-sectional view of the male thread portion of a male tool interface according to the present invention. [Figure 11] FIG. 11 is a partial cross-sectional view of the teeth of the male thread portion shown in FIG. 10. [Figure 12] FIG. 13 is a partial cross-sectional view of the female threaded portion of a female tool interface according to the present invention. [Figure 13] FIG. 13 is a partial cross-sectional view of a tooth of the female thread portion shown in FIG. [Figure 14] 13 is a partial cross-sectional view showing a state in which the male thread portion shown in FIG. 10 is assembled to the female thread portion shown in FIG. 12. [Figure 15] FIG. 13 is a partial cross-sectional view of a groove formed in the female thread portion of the female tool interface according to the present invention for discharging excess pressure of grease. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] As shown in FIG. 1, the first tube 12 comprises a tube body 120. The first tube 12 has an axial length of several meters, for example, about 10 m to 15 m, and extends along a longitudinal axis X. The first tube 12 comprises a male tool joint 18 at a first axial end 121 of the first tube 12. The tube body 120 has an outer diameter that is generally referred to as a nominal outer diameter. The first tube comprises a second axial end 122 opposite the first axial end 121. The second axial end 122 has an outer diameter larger than the outer diameter of the tube body 120.

[0026] 2 is a cross-sectional view of a second tube 14 identical to the first tube 12. The second tube 14 comprises a tube body 140 having a male tool interface at a first axial end 141 and a female tool interface 16 at a second axial end 142. The male tool interface is machined into the outer surface of the first axial end 121. The second axial end 142 has an outer diameter larger than the outer diameter of the tube body 140. The female tool interface is machined into the inner surface of this second end.

[0027] In the following, a connection made between the female tool interface 16 of the second tube 14 and the tool interface 18 of the first tube 12 will be described. For example, Fig. 5 shows a connection according to the invention. This connection can be said to be partially flush insofar as the outer diameter at the level of the made connection is less than 105% or even less than 103% of the outer diameter of the tube body 120, 140. The invention applies to connections that can be made flush, i.e. connections whose outer diameter at the level of the connection is less than 101% of the nominal outer diameter ODnom.

[0028] In the embodiment described above, the first tube 12 and the second tube 14 are identical and each have a male tool interface 18 at a respective first end 121 and 141 and a female tool interface 16 at a respective second end 122 and 142.

[0029] Prior to machining the male tool interface 18, the first distal end 121, 141 is tapered. The tapering reduces the inner diameter of the first end 121, 141 from the narrowing 13 that forms the transition between the tube body and the first end. Preferably, the inner diameter of the first end is limited with respect to the nominal inner diameter of the tube body, so that after assembly of the connection, the inner diameter at the level of the connection is greater than 94% of the nominal inner diameter. The first end 121, 141 extends between the free edge 19 and the tube body. This first end with the male tool interface 18 is adapted to present a specific axial length between the free edge 19 and the tube body, of the order of 20 cm to 30 cm.

[0030] Similarly, before machining the female tool joint 16 at the level of the second distal end 122, 142, the second end is radially expanded. As shown in figures 1 and 2, the radial expansion 15 occurs at a distance from the free edge 17 of the axial second end 122, 142, so that the axial second end 122, 142 presents a certain axial length between the free edge 17 and the tube body, of the order of 20 cm to 30 cm.

[0031] The male tool interface 18 comprises two threaded portions 18a and 18b, which extend along the axis X in two successive portions and are spaced from each other by an unthreaded intermediate portion 20. The male threaded portions 18a and 18b are radially offset with respect to the axis X. In fact, the male tool interface 18 comprises a male abutment shoulder 22 at the unthreaded intermediate portion 20. The male intermediate abutment 22 defines an annular surface in a plane perpendicular to the axis X. Preferably, each of the male threaded portions 18a and 18b comprises a single tip forming a single helix. Preferably, the pitch of each helix of the threaded portions is identical.

[0032] Between the free edge 19 and the first threaded portion 18 a , the unthreaded male inner portion 30 has an inner sealing surface 25 .

[0033] Between the male intermediate abutment 22 and the second male threaded portion 18b, the unthreaded male intermediate portion 20 has an intermediate sealing surface 26.

[0034] The female tool interface 16 comprises two threaded portions 16a and 16b, which extend along the axis X in two successive portions and are spaced from each other by an unthreaded intermediate portion 21. The female threaded portions 16a and 16b are radially offset with respect to the axis X. In fact, the female tool interface 16 comprises an intermediate abutment shoulder 24 at the unthreaded intermediate portion 21. The female intermediate abutment 24 defines an annular surface in a plane perpendicular to the axis X. Preferably, each of the male threaded portions 18a and 18b comprises a single tip forming a single helix. Preferably, the pitch of the respective helices of the male and female threaded portions is identical.

[0035] Between the tube body 14 and the first threaded portion 16 a , the female tool interface 16 includes an unthreaded female inner portion 31 having an inner sealing surface 27 .

[0036] Between the intermediate abutment surface 24 and the second female threaded portion 16b, the unthreaded female intermediate portion 21 has an intermediate sealing surface 29.

[0037] In the assembled position of the connection part shown in FIG. the axial distance "d" of the free edge 19 from the female tool interface 16 is not zero, e.g. greater than 0.1 mm, the helical portion of the first male threaded portion 18a engages with the helical portion of the first female threaded portion 16a; the helical portion of the second male threaded portion 18b engages with the helical portion of the second female threaded portion 16b; The male intermediate abutment portion 22 abuts against the female intermediate abutment portion 24, the male inner seal surface 25 radially interferes and contacts the female inner seal surface 26 to form a metal-to-metal inner seal that protects the connection from internal pressure loads; the male mid-seal surface 27 radially interferes and contacts the female mid-seal surface 28 to form a metal-to-metal mid-seal that protects the connection from external pressure loads; The axial distance of the free edge 17 of the female tool interface from the male tool interface is not zero.

[0038] The connection according to the invention comprises a single axial abutment, perpendicular to the axis X, obtained by contact between the intermediate abutments 22 and 24. Its main function is to indicate the end of threading of the connection.

[0039] The radial thickness of the surfaces in contact with these intermediate abutments 22 and 24 is less than 20% of the cross section of the tube 120 or 140. This cross section is defined between ODnom and IDnom. The machining of the male and female tool interfaces provides manufacturing tolerances that allow the use of tubes with dimensions ODnom and IDnom that meet the specification tolerances set by API standards. The intermediate abutments allow the absorption of some of the compressive stresses of the connection, but due to their dimensions they do not absorb all of the compressive load.

[0040] On either side of the metal-to-metal inner seal, the unthreaded male inner portion 30 is a non-zero radial distance from the unthreaded female inner portion 31. The metal-to-metal inner seal is formed at a distance from the edges of the unthreaded inner regions 30, 31.

[0041] Except for the level of the contact points obtained due to the metal-to-metal mid-seal and due to the abutment of the abutment shoulders 22 and 24, the unthreaded male intermediate portion 20 is at a non-zero radial distance from the unthreaded female inner portion 21. The metal-to-metal mid-seal is formed at a distance from the edges of this unthreaded mid-region 20, 21.

[0042] As shown in FIG. 2, the metal-to-metal inner seal is subjected to more stress than the mid-seal. The mid-seal is useful for ensuring tightness under the stress of external pressure. The thickness of the mid-seal between the second threaded portion and the mid-seal abutment therefore has the thickness of the male tool interface 18 and the female tool interface 16 at the level of its sealing faces. This provides high contact stability, especially under high tensile loads, and the faces do not separate.

[0043] More specifically, according to one embodiment of the present invention, the mid-seal is a cone-to-cone type seal, as shown in Figures 6 and 7. The male mid-seal face 27 and the female mid-seal face 28 have a frusto-conical shape with identical tapers. Alternatively, the faces 27 and 28 can have substantially identical tapers, in the sense that the taper of one is in the range of +1% to -1% of the taper of the other. For example, the taper of the faces 27 and 28 can be in the range of 15% to 25%, e.g., equal to 20% ±1%, or both equal to 20%.

[0044] The male intermediate sealing surface 27 is connected on one side to a cylindrical surface 33 adjacent to the second threaded portion 18b via a concave-convex curve 32 and on the other side to another cylindrical surface 35 adjacent to the male abutment shoulder 22 via another concave-convex curve 34. The cylindrical surface 35 is connected to the male abutment shoulder 22 via a transition 36. The concave-convex curves 32 and 34 are arranged such that they are convex on the side adjacent to the male intermediate sealing surface 27 and concave when connecting to the respective adjacent cylindrical surfaces. In fact, the concave-convex curves 32 and 34 are such that the outer diameter at the level of the cylindrical surface 33 adjacent to the threaded portion 18b is greater than the outer diameter of the cylindrical surface 35 adjacent to the male abutment shoulder 22.

[0045] Similarly, the female intermediate sealing surface 28 is connected on one side via a concave-convex curve 37 to a cylindrical surface 38 adjacent to the second female threaded portion 16b and on the other side via another concave-convex curve 39 to another cylindrical surface 40 adjacent to the female abutment shoulder 24. The concave-convex curves 37 and 39 are arranged such that they are convex on the side adjacent to the female intermediate sealing surface 28 and concave when connecting to the respective adjacent cylindrical surfaces. In fact, the concave-convex curves 37 and 39 are such that the inner diameter at the level of the cylindrical surface 38 adjacent to the female threaded portion 14b is greater than the inner diameter of the cylindrical surface 40 adjacent to the female abutment shoulder 24.

[0046] The uneven surfaces 32, 34, 37, and 39 are connected in a tangential direction. The uneven surfaces 32, 34, 37, and 39 have curved portions that are connected to each other in a tangential direction, and the curve radius is in the range of 3 mm to 30 mm.

[0047] More specifically, the cylindrical surface 40 is connected to the female abutment shoulder 24 via a concave transition 41. The concave transition 41 has a tangentially connected frustoconical portion with a radius of curvature of less than 1 mm. To avoid stress concentrations near the female abutment shoulder 24, the radius of curvature of the concave transition 41 meets the female abutment shoulder 42.

[0048] To avoid stress concentrations near the male abutment shoulder 22, the male abutment shoulder is connected to a cylindrical surface 43 adjacent the end of the first male threaded portion 18a through a concave transition 42 having a large radius.

[0049] Similarly, the female abutment shoulder 24 is connected via a transition 44 to an adjacent cylindrical surface 45 of the first female threaded portion 16a. In fact, taking into consideration that the male threaded portion and the female threaded portion are respectively obtained by machining, the cylindrical surface 45 is adjacent to a groove 46 with a cylindrical bottom for taking out a tool for machining the thread of the first female threaded portion 16a. The cylindrical bottom groove 46 with a cylindrical bottom defines an inner diameter that is larger than the inner diameter of the cylindrical surface 45. The groove 46 has a frustoconical surface that leads to the cylindrical surface 45.

[0050] More specifically, according to one embodiment of the present invention, the inner seal is a ring-to-cone type seal, as shown in Figures 8 and 9. In this embodiment, the male inner seal surface 25 is frustoconical, and the female inner seal surface 26 is ring-shaped. In Figure 8, the female inner seal surface 26 is a curved section resulting from a number of convex bends tangentially adjacent to each other. In one embodiment, two adjacent bends R1 and R2 are provided. The bend R1 is closer to the tube body 140 than the bend R2, and the radius R1 is smaller than the radius R2. Preferably, the radii R1 and R2 are larger than 30 mm. This ring-shaped female inner seal surface 26 is connected to the cylindrical surface 47 on the side of the tube body 140 via a bend 48 having a radius at least three times smaller than the radii R1 and R2. The sealing surface 26 is connected on the opposite side to an adjacent cylindrical surface 50 of the first female threaded portion 16a via a concave-convex surface that is tangentially connected to the cylindrical surface 50 on one side and connected to the sealing surface 26 on the other side.

[0051] For contact with the female inner seal surface 26, the male inner seal surface 25 is provided with a frustoconical section with a taper in the range of 10% to 20%. At the level of the inner circumference of the male tool interface 12, the inner surface 51 of the male tool interface is chamfered. This reduces the thickness of the non-threaded inner part 30 so that, even if the inner seal causes an internal deflection of the seal ring defined between the inner seal surface 25 and the free end 19, the male tool interface 18 does not substantially change the inner passage diameter, called the connection drift diameter.

[0052] The male inner sealing surface 25 is tangentially connected to a convex surface 52 having a large radius of curvature. The convex surface 52 is connected via an interface 53 to a free edge 19 defined perpendicularly to the axis X. Opposite the free edge 19, the male sealing surface is tangentially connected to a cylindrical surface 54 upstream of the start of the thread of the first externally threaded portion 18a. This cylindrical surface 54 allows the use of a tool for machining the thread.

[0053] The main radius R2 is determined to overcome the stress and plastic deformation of the female tool interface 16 above the inner seal. This radius R2 is therefore intended to control the tightness for loads with very high contact pressures. With a gentler contact pressure, the seal ring of the male tool interface also deflects more gently and the location of the sealing point moves towards the inside of the tube body 140. For this reason, the value of radius R2 is not necessary. A radius R1 smaller than radius R2 is therefore used for these operating points. The radial thickness of the sealing surface along axis X is such that a smaller thickness can be used to machine this female inner seal surface 26. Machining of the female tool interface can therefore be performed on a tube regardless of its outer diameter, automatically improving the effectiveness of the female tool interface for a given thickness of the tube. The bend 48 also reduces the amount of material thickness required to machine the female tool interface, improving the connection effectiveness for a given thickness of the tube.

[0054] During threading, the male inner seal surface 25 makes initial contact with curved portion R2. This initial contact can be rough, so by increasing the value of R2, the risk of galling can be reduced. Once contact is established, the remaining threading is completed by moving the male inner seal surface 25 out of contact with curved portion R1. This particular configuration of the female inner seal surface 26 can improve the performance of the connection according to the invention and the number of unthreadings the connection can withstand.

[0055] The thread will now be described.

[0056] In the embodiment shown in Figures 1-9, each of the male threaded portions 18a, 18b and the female threaded portions 16a, 16b includes a single helix.

[0057] However, in variations within the scope of the invention, the male threaded portion and its complementary threaded portion may have the same number of helices, more than two.

[0058] The helical portion is defined by a helical projection. The helical portion has a load flank, a crest, a stab flank, and a thread root. The thread root, like the thread crest, is defined between the load flank and the stub flank, thereby the male tool interface 18 has a helical section in which the root of the thread is radially closer to the longitudinal axis X than the crest of the thread; The female tool interface 16 has a helical portion whose root is radially farther from the longitudinal axis X than the crest of the thread.

[0059] The cross-sectional profile of the helical projection can be said to be substantially trapezoidal insofar as the crest extends axially between the load flank and the stub flank.

[0060] 10 shows a frustoconical portion 74 in two turns of the helices of the first and second externally threaded portions 18a, 18b. The structures described below for the helices are reproduced over at least several turns and over at least three turns while maintaining the dimensions, shapes and proportions defined below.

[0061] The helical part of the male threaded portion has a load flank LFp, a crest 60, a stub flank SFp and a thread root 61. The crest 60 and the root 61 form a segment parallel to the longitudinal axis X. The thread root 61 is connected to the stub flank SFp via a concavely curved transition 62. The concavely curved transition 62 is such that the thread root 61 and the stub flank SFp form an angle greater than 90°. The stub flank SFp is straight and forms an angle 63 with a normal N to the longitudinal axis X. The thread root 61 is connected to the load flank LFp at an end opposite to the end where the thread root 61 is connected to the stub flank SFp via a second concavely curved transition 64. The second concavely curved transition 64 is such that the thread root 61 and the load flank LFp form an angle less than 90°. The load flank LFp is straight and forms an angle 65 with the normal N to the longitudinal axis X.

[0062] Angle 65 is equal to angle 63 plus or minus machining tolerances, i.e., angle 63 with a machining tolerance of ±0.25°. Stub flank SFp is selected to be parallel to load flank LFp, so that the stub flank can carry a portion of the load observed in the connection under a particular compressive stress.

[0063] The angle 63 is, for example, in the range of 1° to 5°, and preferably in the range of 1.25° to 3.75°.

[0064] 11, the curved transition 62 is controlled to preserve the radial dimension of the stub flank SFp. However, the thread root 61 may comprise a step having two staggered cylindrical portions 61a and 61b. Thus, the cylindrical portion 61a directly adjacent the curved transition 62 is radially farther away from the longitudinal axis X than the cylindrical portion 61b adjacent the load flank LFp.

[0065] The crest 60 is connected to the stub flank SFp via a convexly curved transition 66. The crest 60 is connected to the load flank LFp via a convoluted convex surface 67. The convex surface 67 comprises a frustoconical portion 68 adjacent to the cylindrical portion of the crest 60. The frustoconical portion 68 is connected to the load flank LFp via a curved portion 69.

[0066] The radial height of the stub flank SFp is greater than the radial height of the load flank LFp. The male threaded portion thus comprises a frustoconical portion in the direction in which an imaginary line PL (pitch line) passing through the centers of the successive stub flanks SFp and load flanks LFp of the helical portion defines a taper angle 70 with respect to the longitudinal axis X. In this frustoconical portion, the helical portion is defined between two imaginary frustoconical envelope surfaces 71 and 72, respectively, parallel to the pitch line PL. The lower imaginary envelope surface 71 passes through the tangent point between the thread root 61 adjacent to the stub flank SFp and the curved transition 62 of each turn of the helical portion in this frustoconical portion. The upper imaginary envelope surface 72 passes through the tangent point between the convex curved transition 66 adjacent to the stub flank SFp and the thread crest 60.

[0067] Angle 70 is such that the taper of the male threaded portions 18a and / or 18b is in the range of 5% to 15%, preferably in the range of 8% to 12%.

[0068] The helical section comprises, in addition to the above-mentioned frustoconical section 74, a cylindrical section 73 at the end of the helical section. This cylindrical section 73 extends over one or more turns, preferably over less than three turns, in particular over less than two turns. In one embodiment, this end of the helical section having a cylindrical shape 73 is located on the side of the end of the male threaded section that is axially closest to the free edge 19. In particular, each of the first and second male threaded sections 18a, 18b comprises such a cylindrical section 73 adjacent to the frustoconical section 74 of the helical section.

[0069] The cylindrical portion 73 of the helix is ​​such that successive roots 61 of the cylindrical portion are parallel to one another and collinear. The lower imaginary envelope surface 71 is parallel to the axis X in the cylindrical portion, and the upper imaginary envelope surface 72 maintains the same taper in the frustoconical portion 74 and in the cylindrical portion 73.

[0070] The helical portion of the male threaded portion also comprises an imperfection 75 at the opposite end of the male threaded portion, i.e. the end of the helical portion axially furthest from the free edge 19. In particular, the first male threaded portion 18a and the second female threaded portion 18b each comprise an imperfection 75 adjacent to a frustoconical portion 74, which is sandwiched between the imperfection 75 and the cylindrical portion 73. This imperfection 75 is such that the height of the thread is reduced, and the successive crests 60 of this imperfection 75 are parallel to each other and collinear. The upper imaginary envelope surface 72 is parallel to the axis X at this imperfection 75. This imperfection 75 extends over one or more turns, preferably less than three turns, in particular less than two turns. At the imperfection 75, the lower imaginary envelope surface 71 has a taper identical to that observed at the frustoconical portion 74.

[0071] The presence of the cylindrical portion 73 makes it possible to limit the radial extent of the male threaded portion in terms of the wall thickness where the male tool interface is formed, thereby ensuring a greater minimum thickness at the level of the male inner sealing surface 25 and the male intermediate sealing surface 27. This configuration of the male threaded portion improves the gas tightness performance.

[0072] Additionally, the presence of cylindrical portion 73 adjacent to frusto-conical portion 74 avoids a sudden change in stiffness of the unthreaded male inner part 30. This configuration avoids premature plastic deformation in the most highly stressed areas of the connection.

[0073] The helical section of the male threaded portion is such that the stub flank pitch SFLp is constant in the frustoconical portion 74 and also in the imperfection 75. In particular, the pitch is the same in the frustoconical portion 74 and in the imperfection 75. The stub flank pitch LFLp is the same in the frustoconical portion 74 and in the imperfection 75. In addition, this pitch LFLp is equal to the stub flank pitch SFLp.

[0074] For the first male thread portion 18a, the stub flank pitch SFLp1 and the load flank pitch LFLp1 are equal to a constant k1. Similarly, for the second male thread portion 18b, the stub flank pitch SFLp2 and the load flank pitch LFLp2 are equal to this same constant k1. According to the invention, this constant k1 is, for example, in the range of 5 mm to 20 mm, preferably in the range of 6 mm to 8 mm.

[0075] Preferably, the width Wtp of a tooth of the male thread portion, defined as the distance between the stub flank SFp and the load flank LFp at the intersection of the pitch line PL, measured along the longitudinal axis X, is such that this tooth has a width that is less than half the constant k1, in particular a width that is less than 40% of the value k1.

[0076] 12 shows a frustoconical portion 94 in two turns of the helices of the first and second female threaded portions 16a, 16b. The structure described below for the helices is reproduced over at least several turns and over at least three turns while maintaining the dimensions, shapes and proportions defined below.

[0077] The helical part of the female thread portion has a load flank LFb, a crest 80, a stub flank SFb and a thread root 81. The crest 80 and the root 81 form a segment parallel to the longitudinal axis X. The root 81 is connected to the stub flank SFb via a concavely curved transition 82. The concavely curved transition 82 is such that the root 81 and the stub flank SFb form an angle greater than 90°. Similar to the level of the male thread root 61, the root 81 can be provided with a step having two cylindrical portions 81a and 81b arranged in a staggered manner. The cylindrical portion 81a directly adjacent to the concavely curved transition 82 is thus radially closer to the longitudinal axis X than the cylindrical portion 81b of this root 81 adjacent to the load flank LFp.

[0078] The stub flank SFp is straight and forms an angle 83 with respect to the normal N to the longitudinal axis X. The thread root 81 is connected to the load flank LFb at an end opposite to the end at which the thread root 81 is connected to the stub flank SFb via a second concavely curved transition 84 such that the thread root 81 and the load flank LFb form an angle of less than 90°. The load flank LFb is straight and forms an angle 85 with respect to the normal N to the longitudinal axis X.

[0079] Angle 85 is equal to angle 83 plus or minus machining tolerances, ie, angle 83 with a machining tolerance of ±0.25°.

[0080] Angle 85 is equal to angle 65 plus or minus machining tolerances, i.e., angle 65 with a machining tolerance of ±0.25°.

[0081] Angle 83 is equal to angle 63 plus or minus machining tolerances, ie, angle 63 with a machining tolerance of ±0.25°.

[0082] The angle 83 is, for example, in the range of 1° to 5°, and preferably in the range of 1.25° to 3.75°.

[0083] As shown in more detail in FIG. 13, the crest 80 is connected to the stub flank SFb via a convex curved transition 86. The curved transition 86 comprises a tangential transition 86a with the stub flank SFb, a tangential transition 86c with the crest 80 and a frustoconical surface 86b tangentially connected on both sides to the tangential connections 86a and 86c, respectively. The frustoconical surface 86b forms an obtuse angle 86d with the stub flank SFb, for example an opening angle in the range of 190° to 240°, preferably around 225°. The frustoconical surface 86b forms a chamfer that facilitates the insertion of the male tool interface into the female tool interface. In the frustoconical surface 86b, the axial width of the crest 80 is reduced. An additional volume is therefore defined between the frustoconical surface 86b and the complementary profile of the male threaded portion. This volume allows the pressure of the grease in the thread to be reduced.

[0084] The crest 80 is connected to the load flank LFb via a compound convex surface 87 that comprises a frustoconical portion 88 adjacent to the cylindrical portion of the crest 80. The frustoconical portion 88 is connected to the load flank LFb via a curved portion 89.

[0085] The radial height of the load flank LFb is greater than the radial height of the stub flank SFb, such that the female threaded portion comprises a frustoconical portion in a direction in which an imaginary line PL (pitch line) passing through the centers of the successive stub flanks SFb and load flanks LFb of the helical portion defines a taper angle 90 with respect to the longitudinal axis X.

[0086] The taper of this imaginary line is the same as the taper defined by the frustoconical portion 75 of the male threaded portion, and these lines PL overlap in the assembled position of the connection, as shown in FIG.

[0087] In this frustoconical portion 94 of the female threaded section, the helix is ​​defined between two imaginary frustoconical envelope surfaces 91 and 92, which are parallel to the pitch line PL. The upper imaginary envelope surface 91 passes through the tangent point between the thread root 81 and the curved transition 82 adjacent to the stub flank SFb of each turn of the helix in this frustoconical portion 94. The upper imaginary envelope surface 92 passes through the tangent point between the convex curved transition 86 adjacent to the stub flank SFb and the thread crest 80.

[0088] Angle 90 is such that the taper of the internally threaded portions 16a and / or 16b is in the range of 5% to 15%, preferably in the range of 8% to 12%.

[0089] The helix comprises, in addition to the above-mentioned frustoconical portion 94, an incomplete portion at the end of the helix. This incomplete portion 95 extends over one or more turns, preferably over less than three turns, in particular over less than two turns. In one embodiment, this end of the helix is ​​located on the side of the end of the female threaded portion that is axially farthest from the free edge 17 of the female tool interface. In particular, each of the first and second female threaded portions 16a, 16b comprises such an incomplete portion 95 adjacent to the frustoconical portion 94 of the helix.

[0090] The imperfection 95 is such that the thread height is reduced and that successive crests 80 of the imperfection 95 are parallel and collinear with one another. The lower imaginary envelope surface 92 is parallel to the axis X at the imperfection 95. At the imperfection 95, the upper imaginary envelope surface 91 has a taper identical to that observed at the frustoconical portion 94.

[0091] In the assembled position of the male and female tool interfaces, the imperfections 95 of the female threaded portion engage with the corresponding cylindrical portion 73 of the male threaded portion.

[0092] In one embodiment according to the invention, the frusto-conical portion 94 of the female threaded portion has more tips than the frusto-conical portion 74 of the male threaded portion. In fact, the imperfections 75 of the male threaded portion engage with the frusto-conical portion of the female threaded portion in the assembled position of the connection.

[0093] In particular, the first externally threaded portion 18a can have more tips than the second externally threaded portion 18b.

[0094] In particular, the first female threaded portion 16a may have more tips than the second female threaded portion 16b.

[0095] In particular, the frusto-conical portion 74 of the first male threaded portion 18a may have more tip than the frusto-conical portion 74 of the second male threaded portion 18b.

[0096] In particular, the frusto-conical portion 94 of the first female threaded portion 16a may have more tip than the frusto-conical portion 94 of the second female threaded portion 16b.

[0097] The helical section of the female thread portion is such that the stub flank pitch SFLb is constant in the frustoconical portion 94 and also in the imperfection 95. In particular, the pitch is the same in the frustoconical portion 94 and in the imperfection 95. The stub flank pitch LFLb is the same in the frustoconical portion 94 and in the imperfection 95. In addition, this pitch LFLb is equal to the stub flank pitch SFLb.

[0098] For the first female thread portion 16a, the stab flank pitch SFLb1 and the load flank pitch LFLb1 are equal to a constant k2. Similarly, for the second female thread portion 16b, the stab flank pitch SFLb2 and the load flank pitch LFLb2 are equal to this same constant k2.

[0099] According to the present invention, the constants k1 and k2 are equal to each other and can be expressed as a constant k. Taking into account machining tolerances, in the scope of the present invention, k1 is equal to k2±0.05 mm.

[0100] Preferably, the tooth width Wtb of the female threaded portion, defined as the distance between the stab flank SFb and the load flank LFb at the intersection of the pitch line PL measured along the longitudinal axis X, is such that said teeth have a greater width Wtp than the tooth width Wtp of the frustoconical portion 74 of the male threaded portion.

[0101] Indeed, according to the invention, and in the embodiment shown in the figures, it is important to define the teeth of the male threaded portion to have a smaller width than the teeth of the female threaded portion. For example, in the embodiment shown in the figures, the teeth are defined as follows:

number

number

number

number

[0102] Since the teeth on the female thread are larger than the teeth on the male thread, the teeth on the female side are less prone to plastic deformation. Also, in the connection according to the invention, stresses are more clearly seen in the area 99 extending between the first teeth engaged on the side of the inner sealing surfaces 25 and 26 and the sealing surfaces (see FIG. 5).

[0103] The maximum shear lines that can be modeled in a connection according to the invention under compressive load are observed at 45° to the crest 60 on the side where the crest is connected to the stub flank SFp. In contrast, the maximum shear lines that can be modeled in a connection according to the invention under tensile load are observed at 45° to the crest 60 on the side where the crest is connected to the load flank LFp. The intersections between these modeled shear lines make it possible to define triangles of maximum stress above each crest of the male threaded part. These triangles identify the areas where the risk of plastic deformation is greatest in the female tool joint. The inventors have discovered that in order to maintain the effectiveness of the connection, it is essential to limit the height of these triangles and to select the ratios claimed in order to limit the plastic deformation in the female tool joint, the thickness of which is limited by the design of the integral connection.

[0104] 14, in the assembled position, the load flanks LFp and LFb are in contact and axial play 100 is maintained between the stab flanks SFp and SFb. Similarly, radial play 101 is maintained between the male thread crest 60 and the female thread root 81 and when the female thread crest 80 is in contact with the male thread root 61, the imaginary lines 71 and 91 overlap.

[0105] The radial play 101 also limits the size of the area of ​​maximum stress at the female tool interface.

[0106] For example, the play 100 and 101 is in the range of 0.1 mm to 0.5 mm, preferably in the range of 0.2 mm to 0.3 mm. When there is such axial play, the tooth width satisfies the following condition:

number

[0107] Due to the cylindrical conical shape of the male threaded part, there is little free volume between the helices of the assembled male and female threaded parts. When the connection according to the invention is used with threading grease applied to the male and female tool joints before its assembly, there is little free space to avoid a build-up of grease pressure in the connection. According to the invention, in the female threaded part, in particular in the first female threaded part 16a, an annular groove 110 is provided to allow the reception of excess grease that flows back. The advantage of this groove is that it allows the grease to accumulate locally during the threading or use of the connection under certain temperature and pressure conditions. This annular groove is provided in the female threaded part, which is arranged between the two sealing surfaces.

[0108] In the embodiment shown, there is no annular groove in the second female threaded portion since there is no seal between the free edge 17 of the female tool interface and the second female threaded portion.

[0109] In FIG. 15, an annular groove 110 is defined between imaginary inner line 92 and outer line 91. For example, the annular groove 110 has an axial width G of the order of a constant k. The groove 110 has a frustoconical root 111 having a taper identical to that of the female threaded portion. The annular groove is asymmetric. On one side of the root 111, on the side of the inner sealing face 26, the root 111 is connected to a straight portion 112 having an angle 113 with the normal N in the range of 10° to 30°. On the other side of the root 111, on the side of the intermediate sealing face 28, the root 111 is connected to another straight portion 114 having an angle 115 with the normal N in the range of 30° to 85°.

[0110] The grooves allow the grease to escape, even when the connection is placed at a great depth and exposed to temperatures of around 180°C, without temporary loss of the seal or localized plastic deformation of the connection.

Claims

1. 1. A tubular threaded connection for the drilling and / or development of a hydrocarbon well, comprising: a first tube (12) having a male tool interface (18) at a first distal end (121) and a second tube (14) having a female tool interface (16) at a second distal end (142); the male tool interface is attachable to the female tool interface by threading; the first tube is assembled to the second tube and defines a longitudinal axis (X) with the second tube; the male tool interface comprises, in order from the first distal end free edge (19) towards the first tube body (120), a male inner sealing surface (25), a first male threaded portion (18a), a male abutment shoulder (22), a male intermediate sealing surface (27), and a second male threaded portion (18b); the female tool interface comprises a female inner seal surface (26) intended to form an inner seal with the first male seal surface by radial interference when the connection is assembled, a first female threaded portion (16a) engaging the first male threaded portion, a female abutment shoulder (24) abutting the male abutment shoulder, a female mid-seal surface (28) intended to form a mid-seal with the male mid-seal surface by radial interference, and a second female threaded portion (16b) engaging the second male threaded portion, The inner seal is a ring-to-cone type seal, the male inner seal surface being tapered and the female inner seal surface comprising a ring portion, the female inner seal surface being curved from a plurality of tangentially adjacent convex curvatures, the free edge (19) of the first distal end is at a non-zero axial distance (d) from the female tool interface in an assembled position; each of the male threaded portions includes at least one helical section having a load flank, a thread crest, a stab flank, and a thread root; The pitch LFLp1 of the load flank and the pitch SFLp1 of the stab flank of the first male thread portion, and the pitch LFLp2 of the load flank and the pitch SFLp2 of the stab flank of the corresponding second male thread portion are set to satisfy the following condition: [0010] where k1 is a constant for at least two complete turns of each helix. Tubular threaded connections.

2. each of the female threaded portions includes at least one helical section having a load flank, a thread crest, a stab flank, and a thread root; The pitch LFLb1 of the load flank and the pitch SFLb1 of the stub flank of the first female thread portion, and the pitch LFLb2 of the load flank and the pitch SFLb2 of the stub flank of the corresponding second female thread portion are set to satisfy the following condition: [0025] where k2 is a constant for at least two complete turns of each helix. A tubular threaded connection according to claim 1.

3. The constants k1 and k2 are equal to each other. A tubular threaded connection according to claim 2.

4. The first threaded region of the female tool interface has an annular groove (110). A tubular threaded connection according to claim 2 or 3.

5. the helical portion of the first female threaded portion is frustoconical (94) and has a taper in the range of 5% to 15%; A tubular threaded connection according to any one of claims 2 to 4.

6. the helical portion of the first male thread portion includes a frustoconical portion (74) having a taper identical to the taper of the helical portion of the first female thread portion, and a cylindrical portion (73) adjacent to the inner sealing surface, A tubular threaded connection according to any one of the preceding claims.

7. the helical portion of the second female threaded portion is frustoconical (94) and has a taper in the range of 5% to 15%; A tubular threaded connection according to any one of claims 2 to 6.

8. the helical portion of the second male thread portion includes a frustoconical portion (74) having a taper identical to the taper of the helical portion of the second female thread portion, and a cylindrical portion (73) adjacent to the intermediate sealing surface. A tubular threaded connection according to any one of the preceding claims.

9. the mid-seal is a cone-to-cone type seal, the male mid-seal surface and the female mid-seal surface are tapered, particularly having substantially the same taper; A tubular threaded connection according to any one of the preceding claims.

10. The female inner seal surface includes, from the body to the second distal end of the second tube, a first arcuate portion having a radius R1 and a second arcuate portion having a radius R2, the radii satisfying the following condition: [0030] The present invention is characterized in that it satisfies the following: A tubular threaded connection according to any one of the preceding claims.

11. the stub flank and the load flank of the helical portion of the male thread portion are each straight and connected to the adjacent crest (60) and root (61), respectively, via transitions (62, 64, 66, 68); the stab flank of the female thread portion comprises at least one straight portion parallel to the stab flank of the male thread portion for the first thread portion and the second thread portion, A tubular threaded connection according to any one of the preceding claims.

12. the second distal end of the second tube having an outer diameter that is less than 103% of an outer diameter of the second tube. A tubular threaded connection according to any one of the preceding claims.

13. the first and / or second male threaded portion comprises a plurality of helical portions, the plurality of helical portions extending along the same portion of the longitudinal axis, and the starting points of the plurality of helical portions can be evenly distributed in a plane perpendicular to the longitudinal axis of the connection portion, A tubular threaded connection according to any one of the preceding claims.

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